Photophysicochemical properties of aluminium phthalocyanine-platinum conjugates
- Authors: Malinga, Nduduzo Nkanyiso
- Date: 2013 , 2013-04-05
- Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4285 , http://hdl.handle.net/10962/d1002954 , Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Description: The combination of chemotherapy and photodynamic therapy was investigated by synthesis and characterization of octacarboxy phthalocyanine covalent conjugates with platinum complexes. This work presents the synthesis, characterization and photophysicochemical properties of aluminium (diaquaplatinum) octacarboxyphthalocyanine and aluminium (diammine) octacarboxyphthalocyanine. The conjugates were prepared by conjugating aluminium octacarboxy phthalocyanine with potassium tetrachloro platinate to yield aluminium tetrakis and trikis (diaquaplatinum) octacarboxy phthalocyanine. The aluminium octacarboxy phthalocyanine was also conjugated with cis-diamminedichloroplatinum to yield aluminium bis and tris (diaquaplatinum) octacarboxy phthalocyanine. From the characterization of the conjugates it was discovered that the aluminium (diaquaplatinum) octacarboxy phthalocyanine had formed platinum nanoparticles with the Pc acting as a capping agent. The triplet lifetimes decreased with the increasing number of platinum complexesconjugated to the Pc. The heavy atom effect improved the overall photophysicochemical properties.
- Full Text:
- Date Issued: 2013
- Authors: Malinga, Nduduzo Nkanyiso
- Date: 2013 , 2013-04-05
- Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4285 , http://hdl.handle.net/10962/d1002954 , Phthalocyanines , Photochemistry , Photochemotherapy , Aluminium , Platinum , Nanoparticles , Cancer -- Photochemotherapy
- Description: The combination of chemotherapy and photodynamic therapy was investigated by synthesis and characterization of octacarboxy phthalocyanine covalent conjugates with platinum complexes. This work presents the synthesis, characterization and photophysicochemical properties of aluminium (diaquaplatinum) octacarboxyphthalocyanine and aluminium (diammine) octacarboxyphthalocyanine. The conjugates were prepared by conjugating aluminium octacarboxy phthalocyanine with potassium tetrachloro platinate to yield aluminium tetrakis and trikis (diaquaplatinum) octacarboxy phthalocyanine. The aluminium octacarboxy phthalocyanine was also conjugated with cis-diamminedichloroplatinum to yield aluminium bis and tris (diaquaplatinum) octacarboxy phthalocyanine. From the characterization of the conjugates it was discovered that the aluminium (diaquaplatinum) octacarboxy phthalocyanine had formed platinum nanoparticles with the Pc acting as a capping agent. The triplet lifetimes decreased with the increasing number of platinum complexesconjugated to the Pc. The heavy atom effect improved the overall photophysicochemical properties.
- Full Text:
- Date Issued: 2013
Phylogeography and conservation of a newly identified galaxiid from the Joubertina area, South Africa
- Authors: Mataruse, Gamuchirai
- Date: 2013
- Subjects: Galaxiidae -- South Africa -- Joubertina , Phylogeography -- South Africa -- Joubertina , Galaxiidae -- Conservation -- South Africa -- Joubertina , Galaxiidae -- Effect of exotic animals on -- South Africa -- Joubertina , Galaxiidae -- Effect of habitat modification on -- South Africa -- Joubertina , Galaxiidae -- Genetics -- South Africa -- Joubertina , Galaxiidae -- Variation -- South Africa -- Joubertina , Galaxiidae -- Geographical distribution -- South Africa -- Joubertina
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5199 , http://hdl.handle.net/10962/d1003050 , Galaxiidae -- South Africa -- Joubertina , Phylogeography -- South Africa -- Joubertina , Galaxiidae -- Conservation -- South Africa -- Joubertina , Galaxiidae -- Effect of exotic animals on -- South Africa -- Joubertina , Galaxiidae -- Effect of habitat modification on -- South Africa -- Joubertina , Galaxiidae -- Genetics -- South Africa -- Joubertina , Galaxiidae -- Variation -- South Africa -- Joubertina , Galaxiidae -- Geographical distribution -- South Africa -- Joubertina
- Description: The dispersal of freshwater fishes in the Cape Floristic Region of South Africa has been attributed to river capture events and confluence of rivers during sea level regression. The role of low drainage divides and inter-basin water transfers have received less attention. A unique lineage of Galaxias zebratus (hereafter the Joubertina galaxias) occurs in two currently isolated river systems, the Gamtoos and Krom. The present study mapped the distribution of the Joubertina galaxias and used mitochondrial and nuclear DNA sequences to assess the processes that could have influenced its current distribution pattern. Analyses of both mitochondrial cytochrome ♭ and nuclear (S7) sequences revealed that observed genetic differentiation cannot be explained by isolation between the Gamtoos and Krom River systems. No genetic differentiation was found between the Krom River System and the Twee River (a tributary of the Gamtoos River System). Shallow genetic differentiation (0.4% for cytochrome ♭ and 0.3% for S7) was found between the Krom and the remaining populations in the Gamtoos River System. High levels of genetic structuring were observed within the Gamtoos River System with most tributaries having one or more unique alleles. Inter-basin dispersal during pluvial periods or recent human mediated translocation seems to be the most plausible explanations for presence of the Joubertina galaxias in the Krom River System. The present study also assessed the threats and habitat preferences of the Joubertina galaxias, and an evaluation of the conservation status of this lineage was done. The Joubertina galaxias is threatened mainly by alien fish invasion, habitat loss and loss of genetic diversity due to fragmentation of its populations. Due to its very restricted geographic range, small known population sizes and the intensity of threats to this lineage’s survival, this lineage has been assessed as Endangered. The lineage has a restricted Area of Occupancy (AOO) and Extent of Occurrence (EOO). The extent of occurrence has declined in all tributaries and is continuing to decline in all except two tributaries that are secure. The lineage may have had natural fragmentation among its populations, but recent threats have completely isolated the populations. The threats affect the lineage’s survival potential in the four tributaries which have small populations that are not presently viable. The densities observed for the Joubertina galaxias ranged from 0.16 - 1.3 fish /m² and the number of mature individuals for the whole population seems to be less than 2500 mature individuals. There is therefore a need for specific conservation actions to ensure the long-term survival of this unique lineage.
- Full Text:
- Date Issued: 2013
- Authors: Mataruse, Gamuchirai
- Date: 2013
- Subjects: Galaxiidae -- South Africa -- Joubertina , Phylogeography -- South Africa -- Joubertina , Galaxiidae -- Conservation -- South Africa -- Joubertina , Galaxiidae -- Effect of exotic animals on -- South Africa -- Joubertina , Galaxiidae -- Effect of habitat modification on -- South Africa -- Joubertina , Galaxiidae -- Genetics -- South Africa -- Joubertina , Galaxiidae -- Variation -- South Africa -- Joubertina , Galaxiidae -- Geographical distribution -- South Africa -- Joubertina
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5199 , http://hdl.handle.net/10962/d1003050 , Galaxiidae -- South Africa -- Joubertina , Phylogeography -- South Africa -- Joubertina , Galaxiidae -- Conservation -- South Africa -- Joubertina , Galaxiidae -- Effect of exotic animals on -- South Africa -- Joubertina , Galaxiidae -- Effect of habitat modification on -- South Africa -- Joubertina , Galaxiidae -- Genetics -- South Africa -- Joubertina , Galaxiidae -- Variation -- South Africa -- Joubertina , Galaxiidae -- Geographical distribution -- South Africa -- Joubertina
- Description: The dispersal of freshwater fishes in the Cape Floristic Region of South Africa has been attributed to river capture events and confluence of rivers during sea level regression. The role of low drainage divides and inter-basin water transfers have received less attention. A unique lineage of Galaxias zebratus (hereafter the Joubertina galaxias) occurs in two currently isolated river systems, the Gamtoos and Krom. The present study mapped the distribution of the Joubertina galaxias and used mitochondrial and nuclear DNA sequences to assess the processes that could have influenced its current distribution pattern. Analyses of both mitochondrial cytochrome ♭ and nuclear (S7) sequences revealed that observed genetic differentiation cannot be explained by isolation between the Gamtoos and Krom River systems. No genetic differentiation was found between the Krom River System and the Twee River (a tributary of the Gamtoos River System). Shallow genetic differentiation (0.4% for cytochrome ♭ and 0.3% for S7) was found between the Krom and the remaining populations in the Gamtoos River System. High levels of genetic structuring were observed within the Gamtoos River System with most tributaries having one or more unique alleles. Inter-basin dispersal during pluvial periods or recent human mediated translocation seems to be the most plausible explanations for presence of the Joubertina galaxias in the Krom River System. The present study also assessed the threats and habitat preferences of the Joubertina galaxias, and an evaluation of the conservation status of this lineage was done. The Joubertina galaxias is threatened mainly by alien fish invasion, habitat loss and loss of genetic diversity due to fragmentation of its populations. Due to its very restricted geographic range, small known population sizes and the intensity of threats to this lineage’s survival, this lineage has been assessed as Endangered. The lineage has a restricted Area of Occupancy (AOO) and Extent of Occurrence (EOO). The extent of occurrence has declined in all tributaries and is continuing to decline in all except two tributaries that are secure. The lineage may have had natural fragmentation among its populations, but recent threats have completely isolated the populations. The threats affect the lineage’s survival potential in the four tributaries which have small populations that are not presently viable. The densities observed for the Joubertina galaxias ranged from 0.16 - 1.3 fish /m² and the number of mature individuals for the whole population seems to be less than 2500 mature individuals. There is therefore a need for specific conservation actions to ensure the long-term survival of this unique lineage.
- Full Text:
- Date Issued: 2013
Polyunsaturated fatty acid metabolism and effects on colon cancer cell biology in vitro.
- Authors: Bulcao, Candice
- Date: 2013
- Subjects: Unsaturated fatty acids , Unsaturated fatty acids in human nutrition , Colon (Anatomy)-- Cancer , Cancer -- Nutritional aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4137 , http://hdl.handle.net/10962/d1016128
- Description: Colon cancer is a leading cause of cancer related deaths worldwide. Lifestyle factors such as diet and exercise have been implicated as important agents in colon cancer development and progression. Epidemiological, in vivo and in vitro studies have found that n-3 polyunsaturated fatty acids (PUFAs) reduce colon carcinoma. The role of n-6 PUFAs remains a controversial topic, with studies indicating both promoting and preventing capabilities published. In order to better understand the effects of PUFAs on colon carcinoma, it is important to have an understanding of how they will be broken down in the body. During this study, in silico metabolism of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) predicted the formation of hydroxy-, di-hydroxy- and epoxy-FAs. A gas chromatography-mass spectrometry method was developed and validated for the detection of these PUFAs and their cytochrome P450 (CYP) metabolites. A human liver microsomal system for the in vitro metabolism of EPA, DHA and AA was optimised in terms of microsomal and PUFA concentration. The system resulted in the metabolism of the positive control, lauric acid, to 12-hydroxy-lauric acid but was unable to metabolise the PUFAs of interest. EPA, DHA and AA reduced cell viability in the colon carcinoma cell lines SW480 and SW620 in the micromolar concentration range (25 – 200 μM). The CYP epoxidation metabolite of EPA, 17, 18-epoxyeicosatetraenoic acid (17, 18-EpETE) resulted in a significant reduction in SW480 cell viability relative to the parent compound at lower concentrations (25 and 50 μM). Annexin V apoptosis analysis revealed that EPA and 17, 18- EpETE did not result in apoptosis in SW480 cells at a concentration of 25 μM and over an incubation period of 24 hours. A significant reduction in reactive oxygen species production was seen in SW480 cells after incubation with 25 μM 17, 18-EpETE for 24 hours. EPA and 17, 18-EpETE were implicated in the reduction of colon cancer metastasis since they were able to reduce SW480 migration and anchorage independent cell growth. These results indicate that the dietary intake of EPA, DHA and AA may be beneficial to one’s health due to the negative effects that these PUFAs had on colon carcinoma. Future studies are needed to confirm these benefits and compare the effects of the PUFAs to their CYP-metabolites.
- Full Text:
- Date Issued: 2013
- Authors: Bulcao, Candice
- Date: 2013
- Subjects: Unsaturated fatty acids , Unsaturated fatty acids in human nutrition , Colon (Anatomy)-- Cancer , Cancer -- Nutritional aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4137 , http://hdl.handle.net/10962/d1016128
- Description: Colon cancer is a leading cause of cancer related deaths worldwide. Lifestyle factors such as diet and exercise have been implicated as important agents in colon cancer development and progression. Epidemiological, in vivo and in vitro studies have found that n-3 polyunsaturated fatty acids (PUFAs) reduce colon carcinoma. The role of n-6 PUFAs remains a controversial topic, with studies indicating both promoting and preventing capabilities published. In order to better understand the effects of PUFAs on colon carcinoma, it is important to have an understanding of how they will be broken down in the body. During this study, in silico metabolism of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) predicted the formation of hydroxy-, di-hydroxy- and epoxy-FAs. A gas chromatography-mass spectrometry method was developed and validated for the detection of these PUFAs and their cytochrome P450 (CYP) metabolites. A human liver microsomal system for the in vitro metabolism of EPA, DHA and AA was optimised in terms of microsomal and PUFA concentration. The system resulted in the metabolism of the positive control, lauric acid, to 12-hydroxy-lauric acid but was unable to metabolise the PUFAs of interest. EPA, DHA and AA reduced cell viability in the colon carcinoma cell lines SW480 and SW620 in the micromolar concentration range (25 – 200 μM). The CYP epoxidation metabolite of EPA, 17, 18-epoxyeicosatetraenoic acid (17, 18-EpETE) resulted in a significant reduction in SW480 cell viability relative to the parent compound at lower concentrations (25 and 50 μM). Annexin V apoptosis analysis revealed that EPA and 17, 18- EpETE did not result in apoptosis in SW480 cells at a concentration of 25 μM and over an incubation period of 24 hours. A significant reduction in reactive oxygen species production was seen in SW480 cells after incubation with 25 μM 17, 18-EpETE for 24 hours. EPA and 17, 18-EpETE were implicated in the reduction of colon cancer metastasis since they were able to reduce SW480 migration and anchorage independent cell growth. These results indicate that the dietary intake of EPA, DHA and AA may be beneficial to one’s health due to the negative effects that these PUFAs had on colon carcinoma. Future studies are needed to confirm these benefits and compare the effects of the PUFAs to their CYP-metabolites.
- Full Text:
- Date Issued: 2013
Population size, demography and spatial ecology of cheetahs in the Timbavati Private Nature Reserve, South Africa
- Authors: Dyer, Siobhan Margaret
- Date: 2013
- Subjects: Timbavati Game Reserve (South Africa) Cheetah -- South Africa -- Timbavati Game Reserve Spatial behavior in animals Cheetah -- Behavior -- South Africa -- Timbavati Game Reserve Animal populations Population biology Rare mammals -- South Africa -- Timbavati Game Reserve Cheetah -- Effect of human beings on -- South Africa -- Timbavati Game Reserve
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5608 , http://hdl.handle.net/10962/d1002058
- Description: The cheetah (Acinonyx jubatus) has experienced a drastic decline in numbers over the last 20 years globally and is currently listed as vulnerable by the International Union for the Conservation of Nature (IUCN). In South Africa, there are only an estimated 763 free-ranging cheetahs and conflict with humans is arguably the most significant reason for this low number. The aim of my study was to determine the population size and demographic characteristics of the cheetah population within the Timbavati Private Nature Reserve (TPNR), South Africa, and to contribute to a better understanding of cheetah space use and habitat selection. The research was conducted on TPNR between November 2009 and June 2011 and I used a photographic survey to assess cheetah population size and demographic characteristics. Location data was obtained by collaring two adult male cheetahs with GPS/GSM collars and ad hoc sightings data from across the reserve for an adult female with cubs and three adolescent females. A relatively high minimum population density of 4.46 cheetahs/100km² was estimated, signifying a relatively healthy cheetah population. The sex ratio data indicated a higher male to female ratio and an average litter size of three cubs. The relatively high cub survival rate and density is promising in terms of the status of species within the area, as the data denote the success and potential persistence of the species. Cheetah home ranges varied between 20.97km² for the female with cubs and 659.65km² for the younger collared male. Season did not appear to be a determining factor in terms of home range sizes for the three social groups within the TPNR. However, the males did show a slight increase in their home range sizes during the dry season when resources where presumably more widespread. My results indicate that the cheetah is an adaptable species, flexible in behaviour and able to tolerate a variety of habitat types. Such knowledge is fundamental for planning and implementing the effective management and conservation of cheetahs in South Africa.
- Full Text:
- Date Issued: 2013
- Authors: Dyer, Siobhan Margaret
- Date: 2013
- Subjects: Timbavati Game Reserve (South Africa) Cheetah -- South Africa -- Timbavati Game Reserve Spatial behavior in animals Cheetah -- Behavior -- South Africa -- Timbavati Game Reserve Animal populations Population biology Rare mammals -- South Africa -- Timbavati Game Reserve Cheetah -- Effect of human beings on -- South Africa -- Timbavati Game Reserve
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5608 , http://hdl.handle.net/10962/d1002058
- Description: The cheetah (Acinonyx jubatus) has experienced a drastic decline in numbers over the last 20 years globally and is currently listed as vulnerable by the International Union for the Conservation of Nature (IUCN). In South Africa, there are only an estimated 763 free-ranging cheetahs and conflict with humans is arguably the most significant reason for this low number. The aim of my study was to determine the population size and demographic characteristics of the cheetah population within the Timbavati Private Nature Reserve (TPNR), South Africa, and to contribute to a better understanding of cheetah space use and habitat selection. The research was conducted on TPNR between November 2009 and June 2011 and I used a photographic survey to assess cheetah population size and demographic characteristics. Location data was obtained by collaring two adult male cheetahs with GPS/GSM collars and ad hoc sightings data from across the reserve for an adult female with cubs and three adolescent females. A relatively high minimum population density of 4.46 cheetahs/100km² was estimated, signifying a relatively healthy cheetah population. The sex ratio data indicated a higher male to female ratio and an average litter size of three cubs. The relatively high cub survival rate and density is promising in terms of the status of species within the area, as the data denote the success and potential persistence of the species. Cheetah home ranges varied between 20.97km² for the female with cubs and 659.65km² for the younger collared male. Season did not appear to be a determining factor in terms of home range sizes for the three social groups within the TPNR. However, the males did show a slight increase in their home range sizes during the dry season when resources where presumably more widespread. My results indicate that the cheetah is an adaptable species, flexible in behaviour and able to tolerate a variety of habitat types. Such knowledge is fundamental for planning and implementing the effective management and conservation of cheetahs in South Africa.
- Full Text:
- Date Issued: 2013
Production of recombinant human CD21 and CD23 : towards a better understanding of their interaction
- Authors: Van Zyl, Dwain George
- Date: 2013
- Subjects: Immunoglobulins , Fc receptors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10365 , http://hdl.handle.net/10948/d10211135
- Description: The prevalence of allergic diseases has dramatically increased over the last three decades. Presently, it is estimated that 20-30 per cent of the developed world suffers from allergic diseases. The majority of allergic diseases are rooted in the activities of IgE; an immunoglobulin which exerts its effector functions by interacting with a network of proteins. This network includes its low affinity receptor CD23. Cross linking of membrane IgE and CD21 by soluble CD23 results in an increase in IgE synthesis. This marks the interaction between CD23 and CD21 as an attractive therapeutic target. However, details regarding this interaction are inadequate for rational drug design. To obtain a deeper understanding of the CD23-CD21 interaction recombinant human CD21 (SCR1-2 and SCR5-8) and CD23 (16 kD and 25 kDa) were produced. The cloning, expression and purification of recombinant proteins comprised a significant portion of this study. Recombinant CD23 was expressed as inclusion bodies, refolded by rapid dilution and purified by size exclusion chromatography. Conversely, recombinant CD21 was expressed as soluble MBP-fusions and purified with an amylose affinity resin. The interaction between recombinant CD23 and CD21 was analysed by flow cytometry and ELISA experiments. Flow cytometry showed that 16 kDa and 25 kDa CD23 interacted with SCR5-8 to the same extent. Semi-quantitative ELISA experiments showed that both SCR1-2 and SCR5-8 were able to interact with 16 kDa and 25 kDa CD23. This suggests that the binding sites of SCR1-2 and SCR5-8 occur on 16 kDa CD23. Furthermore, since proteins were expressed in E. coli it suggests that the CD23-CD21 interaction does not require glycosylation. Furthermore, considering what is known about the SCR1-2-CD23 interaction from previous NMR studies; i.e. that the C-terminal tail (residues residues 289-298) of CD23 is responsible for binding SCR1-2, indicates that SCR5-8 binds somewhere within the lectin domain of CD23. This indicates that the CD23-CD21 interaction involves C-terminal tail-SCR1-2 and lectin domain-SCR5-8 interactions.
- Full Text:
- Date Issued: 2013
- Authors: Van Zyl, Dwain George
- Date: 2013
- Subjects: Immunoglobulins , Fc receptors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10365 , http://hdl.handle.net/10948/d10211135
- Description: The prevalence of allergic diseases has dramatically increased over the last three decades. Presently, it is estimated that 20-30 per cent of the developed world suffers from allergic diseases. The majority of allergic diseases are rooted in the activities of IgE; an immunoglobulin which exerts its effector functions by interacting with a network of proteins. This network includes its low affinity receptor CD23. Cross linking of membrane IgE and CD21 by soluble CD23 results in an increase in IgE synthesis. This marks the interaction between CD23 and CD21 as an attractive therapeutic target. However, details regarding this interaction are inadequate for rational drug design. To obtain a deeper understanding of the CD23-CD21 interaction recombinant human CD21 (SCR1-2 and SCR5-8) and CD23 (16 kD and 25 kDa) were produced. The cloning, expression and purification of recombinant proteins comprised a significant portion of this study. Recombinant CD23 was expressed as inclusion bodies, refolded by rapid dilution and purified by size exclusion chromatography. Conversely, recombinant CD21 was expressed as soluble MBP-fusions and purified with an amylose affinity resin. The interaction between recombinant CD23 and CD21 was analysed by flow cytometry and ELISA experiments. Flow cytometry showed that 16 kDa and 25 kDa CD23 interacted with SCR5-8 to the same extent. Semi-quantitative ELISA experiments showed that both SCR1-2 and SCR5-8 were able to interact with 16 kDa and 25 kDa CD23. This suggests that the binding sites of SCR1-2 and SCR5-8 occur on 16 kDa CD23. Furthermore, since proteins were expressed in E. coli it suggests that the CD23-CD21 interaction does not require glycosylation. Furthermore, considering what is known about the SCR1-2-CD23 interaction from previous NMR studies; i.e. that the C-terminal tail (residues residues 289-298) of CD23 is responsible for binding SCR1-2, indicates that SCR5-8 binds somewhere within the lectin domain of CD23. This indicates that the CD23-CD21 interaction involves C-terminal tail-SCR1-2 and lectin domain-SCR5-8 interactions.
- Full Text:
- Date Issued: 2013
Profiling for volatile compounds in the Kgalagadi desert truffle
- Authors: Bogopa, Juda
- Date: 2013
- Subjects: Desert plants -- Botswana -- Kgalagadi District Supercritical fluid extraction Gas chromatography Mass spectrometry Tuberaceae -- Analysis -- Botswana -- Kgalagadi District Truffles -- Analysis -- Botswana -- Kgalagadi District
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4280 , http://hdl.handle.net/10962/d1002006
- Description: The thesis focuses on ‘green’ sample preparation techniques that utilise minimal or no organic solvents thereby producing negligible volumes of organic waste, to ensure safety both to user and the environment. Volatile compounds were extracted and pre-concentrated from Kgalagadi desert truffles (kalaharituber) by headspace solid phase microextraction (HSSPME) and supercritical fluid extraction (SFE). PHWE was employed for the extraction of amino acids and fatty acids. Subsequent analysis of volatile compounds was carried out by gas chromatography coupled with mass spectrometry. Four types of HS-SPME fibers (PDMS 100 μm, PDMS 7 μm, Polyacrylate 85 μm, CAR/DVB/PDMS 50/30 μm) were evaluated. A total of 24 volatile compounds with a molecular weight range from 110 to 354, the most prominent peak being 2-t-Butyl-2,3-dimethyl-3-buten-1-ol (C₁₀H₂₀O, MW 156) were detected after sampling with a PDMS 100 μm fiber. Less volatile compounds were detected after SFE with CO2. A total of 16 amino acids were identified while 17 fatty acids (MW from 132.12 to 367.49) were also identified. The characteristic profile of the Kgalagadi desert truffle was found to contain mainly fatty acid methyl esters and unsaturated aliphatic hydrocarbons. The most prominent compound peaks identified were; 2-t-butyl-2,3-dimethyl- 3-buten-1-ol, disulfide, ethyl benzoic acid 2-4-dhydroxy-3,6-dimethyl-methyl ester, 8,11- octadecanoic acid methyl ester, benzoic acid, 2,4-dihydroxy-3,6-dimethyl-methyl ester, isoquinoline, 1 butyl-3,4-dihydro and 3-heptanone, 6 methyl. Optimization results indicated that fresh slices from the heart of truffles were the best to use for HS-SPME-GCMS volatile compound analysis as they showed a higher sensitivity
- Full Text:
- Date Issued: 2013
- Authors: Bogopa, Juda
- Date: 2013
- Subjects: Desert plants -- Botswana -- Kgalagadi District Supercritical fluid extraction Gas chromatography Mass spectrometry Tuberaceae -- Analysis -- Botswana -- Kgalagadi District Truffles -- Analysis -- Botswana -- Kgalagadi District
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4280 , http://hdl.handle.net/10962/d1002006
- Description: The thesis focuses on ‘green’ sample preparation techniques that utilise minimal or no organic solvents thereby producing negligible volumes of organic waste, to ensure safety both to user and the environment. Volatile compounds were extracted and pre-concentrated from Kgalagadi desert truffles (kalaharituber) by headspace solid phase microextraction (HSSPME) and supercritical fluid extraction (SFE). PHWE was employed for the extraction of amino acids and fatty acids. Subsequent analysis of volatile compounds was carried out by gas chromatography coupled with mass spectrometry. Four types of HS-SPME fibers (PDMS 100 μm, PDMS 7 μm, Polyacrylate 85 μm, CAR/DVB/PDMS 50/30 μm) were evaluated. A total of 24 volatile compounds with a molecular weight range from 110 to 354, the most prominent peak being 2-t-Butyl-2,3-dimethyl-3-buten-1-ol (C₁₀H₂₀O, MW 156) were detected after sampling with a PDMS 100 μm fiber. Less volatile compounds were detected after SFE with CO2. A total of 16 amino acids were identified while 17 fatty acids (MW from 132.12 to 367.49) were also identified. The characteristic profile of the Kgalagadi desert truffle was found to contain mainly fatty acid methyl esters and unsaturated aliphatic hydrocarbons. The most prominent compound peaks identified were; 2-t-butyl-2,3-dimethyl- 3-buten-1-ol, disulfide, ethyl benzoic acid 2-4-dhydroxy-3,6-dimethyl-methyl ester, 8,11- octadecanoic acid methyl ester, benzoic acid, 2,4-dihydroxy-3,6-dimethyl-methyl ester, isoquinoline, 1 butyl-3,4-dihydro and 3-heptanone, 6 methyl. Optimization results indicated that fresh slices from the heart of truffles were the best to use for HS-SPME-GCMS volatile compound analysis as they showed a higher sensitivity
- Full Text:
- Date Issued: 2013
Real options valuation for South African nuclear waste management using a fuzzy mathematical approach
- Authors: Montsho, Obakeng Johannes
- Date: 2013 , 2013-06-06
- Subjects: Fuzzy mathematics , Real options (Finance) , Fuzzy sets , Business mathematics , Radioactive waste disposal -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5398 , http://hdl.handle.net/10962/d1003051 , Fuzzy mathematics , Real options (Finance) , Fuzzy sets , Business mathematics , Radioactive waste disposal -- South Africa
- Description: The feasibility of capital projects in an uncertain world can be determined in several ways. One of these methods is real options valuation which arose from financial option valuation theory. On the other hand fuzzy set theory was developed as a mathematical framework to capture uncertainty in project management. The valuation of real options using fuzzy numbers represents an important refinement to determining capital projects' feasibility using the real options approach. The aim of this study is to determine whether the deferral of the decommissioning time (by a decade) of an electricity-generating nuclear plant in South Africa increases decommissioning costs. Using the fuzzy binomial approach, decommissioning costs increase when decommissioning is postponed by a decade whereas use of the fuzzy Black-Scholes approach yields the opposite result. A python code was developed to assist in the computation of fuzzy binomial trees required in our study and the results of the program are incorporated in this thesis. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Montsho, Obakeng Johannes
- Date: 2013 , 2013-06-06
- Subjects: Fuzzy mathematics , Real options (Finance) , Fuzzy sets , Business mathematics , Radioactive waste disposal -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5398 , http://hdl.handle.net/10962/d1003051 , Fuzzy mathematics , Real options (Finance) , Fuzzy sets , Business mathematics , Radioactive waste disposal -- South Africa
- Description: The feasibility of capital projects in an uncertain world can be determined in several ways. One of these methods is real options valuation which arose from financial option valuation theory. On the other hand fuzzy set theory was developed as a mathematical framework to capture uncertainty in project management. The valuation of real options using fuzzy numbers represents an important refinement to determining capital projects' feasibility using the real options approach. The aim of this study is to determine whether the deferral of the decommissioning time (by a decade) of an electricity-generating nuclear plant in South Africa increases decommissioning costs. Using the fuzzy binomial approach, decommissioning costs increase when decommissioning is postponed by a decade whereas use of the fuzzy Black-Scholes approach yields the opposite result. A python code was developed to assist in the computation of fuzzy binomial trees required in our study and the results of the program are incorporated in this thesis. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
Relating vegetation condition to grazing management systems in the central Keiskamma catchment, Eastern Cape Province, South Africa
- Authors: Ndou, Naledzani Nyahman
- Date: 2013
- Subjects: Grazing -- Management , Grazing -- South Africa -- Management , Vegetation and climate -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10673 , http://hdl.handle.net/10948/d1020645
- Description: Vegetation degradation in South Africa has been identified as a serious environmental problem, especially impacting communal areas. This study investigated the spatial distribution of vegetative condition, along with related changes, deterioration and trends, across the communal villages of the central Keiskamma catchment, Eastern Cape Province. The principal hypothesis of this study was that differences in grazing management strategies may explain the variations in vegetation condition within these communal areas. This investigation assessed the status and condition of vegetation in relation to local institutional grazing management systems, in association with factoring in relevant topographical and physical elements. Topographic homogeneity of the study area was tested by extracting topographic parameters from a DEM and performing a Chi squared test. Remote sensing techniques were used to analyse the spatial and temporal variations in vegetation condition between the villages. Landsat TM images, from 1984 and 1999, in conjunction with SPOT imagery of 2011, were used to assess the spatial trends in vegetation. Land use and cover maps were generated, comprising five categories of land cover, viz. intact vegetation; transformed vegetation; degraded vegetation; bare surfaces; and water. The classification of the images was achieved using the supervised object-oriented classification techniques, which aggregates pixels of each class into homogeneous objects. Information regarding existence and functionality of local institutional structures was obtained through structured interview method. Vegetation condition was correlated to grazing management systems, with the logistic regression confirming a significant relationship between vegetation condition and grazing management systems. Analysis of vegetation condition trends revealed a decline in pristine vegetation with an increase in degraded vegetation and exposed soil throughout the villages. However, it was observed that the decrease in pristine vegetation, with the associated increase in degraded vegetation and soil, do not occur evenly among the villages of the central Keiskamma catchment; the communal areas surrounding certain villages exhibited severe degradation of soil and vegetation, while other villages demonstrated less or minimal deterioration in their environs. The topographic homogeneity of the study locale lent credence to the theory that the uneven distribution of vegetation conditions between the villages is not controlled by topographic factors. Analysis of the data, collected through interviews, revealed differences in the functionality of institutional structures between villages. A statistically significant correlation between the vegetative condition and implementation of grazing management systems, supports the postulated concept that the variances in vegetation condition of the central Keiskamma catchment reflect the efficacy or inefficiency of the settlements‘ grazing management systems. Through gathering, analysing and assessing all the data, a conclusion was drawn, which advances that the primary requirement for remedial action in reversing the current decline in vegetation condition is strengthening the local institutional management regimes throughout all villages under study.
- Full Text:
- Date Issued: 2013
- Authors: Ndou, Naledzani Nyahman
- Date: 2013
- Subjects: Grazing -- Management , Grazing -- South Africa -- Management , Vegetation and climate -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10673 , http://hdl.handle.net/10948/d1020645
- Description: Vegetation degradation in South Africa has been identified as a serious environmental problem, especially impacting communal areas. This study investigated the spatial distribution of vegetative condition, along with related changes, deterioration and trends, across the communal villages of the central Keiskamma catchment, Eastern Cape Province. The principal hypothesis of this study was that differences in grazing management strategies may explain the variations in vegetation condition within these communal areas. This investigation assessed the status and condition of vegetation in relation to local institutional grazing management systems, in association with factoring in relevant topographical and physical elements. Topographic homogeneity of the study area was tested by extracting topographic parameters from a DEM and performing a Chi squared test. Remote sensing techniques were used to analyse the spatial and temporal variations in vegetation condition between the villages. Landsat TM images, from 1984 and 1999, in conjunction with SPOT imagery of 2011, were used to assess the spatial trends in vegetation. Land use and cover maps were generated, comprising five categories of land cover, viz. intact vegetation; transformed vegetation; degraded vegetation; bare surfaces; and water. The classification of the images was achieved using the supervised object-oriented classification techniques, which aggregates pixels of each class into homogeneous objects. Information regarding existence and functionality of local institutional structures was obtained through structured interview method. Vegetation condition was correlated to grazing management systems, with the logistic regression confirming a significant relationship between vegetation condition and grazing management systems. Analysis of vegetation condition trends revealed a decline in pristine vegetation with an increase in degraded vegetation and exposed soil throughout the villages. However, it was observed that the decrease in pristine vegetation, with the associated increase in degraded vegetation and soil, do not occur evenly among the villages of the central Keiskamma catchment; the communal areas surrounding certain villages exhibited severe degradation of soil and vegetation, while other villages demonstrated less or minimal deterioration in their environs. The topographic homogeneity of the study locale lent credence to the theory that the uneven distribution of vegetation conditions between the villages is not controlled by topographic factors. Analysis of the data, collected through interviews, revealed differences in the functionality of institutional structures between villages. A statistically significant correlation between the vegetative condition and implementation of grazing management systems, supports the postulated concept that the variances in vegetation condition of the central Keiskamma catchment reflect the efficacy or inefficiency of the settlements‘ grazing management systems. Through gathering, analysing and assessing all the data, a conclusion was drawn, which advances that the primary requirement for remedial action in reversing the current decline in vegetation condition is strengthening the local institutional management regimes throughout all villages under study.
- Full Text:
- Date Issued: 2013
Responses to the linked stressors of climate change and HIV/AIDS amongst vulnerable rural households in the Eastern Cape, South Africa
- Authors: Clarke, Caryn Lee
- Date: 2013
- Subjects: Climatic changes -- South Africa -- Eastern Cape Climatic changes -- Health aspects -- South Africa -- Eastern Cape Climatic changes -- Economic aspects -- South Africa -- Eastern Cape HIV infections -- Economic aspects -- South Africa -- Eastern Cape AIDS (Disease) -- Economic aspects -- South Africa -- Eastern Cape HIV infections -- Social aspects -- South Africa -- Eastern Cape AIDS (Disease) -- Social aspects -- South Africa -- Eastern Cape Poverty -- Social aspects -- South Africa -- Eastern Cape Income -- South Africa -- Eastern Cape Human capital -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4732 , http://hdl.handle.net/10962/d1003818
- Description: Climate change and the HIV/AIDS epidemic are two of the most critical long-term global challenges, especially for Africa and even more so Southern Africa. There is great concern that the poor will be unable to adapt to the impacts of climate variability and change while HIV/AIDS will exacerbate the impacts of such stressors and deepen the insecurities of many communities already affected by this disease. Studies that consider the interlinked effects of climate change and HIV/AIDS along with other multiple stressors are increasingly needed. This study, located in two rural communities in the Eastern Cape Province of South Africa, namely Lesseyton and Willowvale, assessed the responses of vulnerable households to the linked shocks and stressors of climate change and HIV/AIDS. This involved assessing, through household surveys, life history interviews and Participatory Learning and Action (PLA), the way in which multiple stressors interacted and affected vulnerable households, the way in which these households responded to and coped with such shocks and stressors, and the barriers which prevented them from coping and adapting effectively. Unemployment emerged as the dominant stress amongst households. The lack of development and having too few opportunities for employment has limited vulnerable households from being able to invest in assets, such as education or farming equipment. This, in combination with the impacts of increased food and water insecurity from recent drought, has created an extremely vulnerable environment for these households. They rely largely on two important safety-nets, namely social capital and the use of natural and cultivated resources; however the latter has been limited due to the impacts of water scarcity and an inability to farm. It was evident that there was little planned long-term adaptation amongst households and from government. Maladaptive short-term coping strategies, such numerous household members depending on one social grant and transactional sex, were too often relied upon, and although they may have helped relieve the stress of shocks momentarily, they did not provide for the long-term well-being of individuals and households. Poor communication and capacity between the different levels of government and between the government (especially at the local level) and the two rural communities has created an environment full of uncertainty and lacking in advocacy. Local government needs increased human, informational, and financial capacity and a clear delegation of responsibilities amongst the different departments in order for the two communities to benefit from the implementation of support strategies. There is also a great need for educational programmes and capacity development within the two rural communities, particularly based on improved coping and longer-term adaptation strategies in response to climate change in order for households to better prepare themselves for the future.
- Full Text:
- Date Issued: 2013
- Authors: Clarke, Caryn Lee
- Date: 2013
- Subjects: Climatic changes -- South Africa -- Eastern Cape Climatic changes -- Health aspects -- South Africa -- Eastern Cape Climatic changes -- Economic aspects -- South Africa -- Eastern Cape HIV infections -- Economic aspects -- South Africa -- Eastern Cape AIDS (Disease) -- Economic aspects -- South Africa -- Eastern Cape HIV infections -- Social aspects -- South Africa -- Eastern Cape AIDS (Disease) -- Social aspects -- South Africa -- Eastern Cape Poverty -- Social aspects -- South Africa -- Eastern Cape Income -- South Africa -- Eastern Cape Human capital -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4732 , http://hdl.handle.net/10962/d1003818
- Description: Climate change and the HIV/AIDS epidemic are two of the most critical long-term global challenges, especially for Africa and even more so Southern Africa. There is great concern that the poor will be unable to adapt to the impacts of climate variability and change while HIV/AIDS will exacerbate the impacts of such stressors and deepen the insecurities of many communities already affected by this disease. Studies that consider the interlinked effects of climate change and HIV/AIDS along with other multiple stressors are increasingly needed. This study, located in two rural communities in the Eastern Cape Province of South Africa, namely Lesseyton and Willowvale, assessed the responses of vulnerable households to the linked shocks and stressors of climate change and HIV/AIDS. This involved assessing, through household surveys, life history interviews and Participatory Learning and Action (PLA), the way in which multiple stressors interacted and affected vulnerable households, the way in which these households responded to and coped with such shocks and stressors, and the barriers which prevented them from coping and adapting effectively. Unemployment emerged as the dominant stress amongst households. The lack of development and having too few opportunities for employment has limited vulnerable households from being able to invest in assets, such as education or farming equipment. This, in combination with the impacts of increased food and water insecurity from recent drought, has created an extremely vulnerable environment for these households. They rely largely on two important safety-nets, namely social capital and the use of natural and cultivated resources; however the latter has been limited due to the impacts of water scarcity and an inability to farm. It was evident that there was little planned long-term adaptation amongst households and from government. Maladaptive short-term coping strategies, such numerous household members depending on one social grant and transactional sex, were too often relied upon, and although they may have helped relieve the stress of shocks momentarily, they did not provide for the long-term well-being of individuals and households. Poor communication and capacity between the different levels of government and between the government (especially at the local level) and the two rural communities has created an environment full of uncertainty and lacking in advocacy. Local government needs increased human, informational, and financial capacity and a clear delegation of responsibilities amongst the different departments in order for the two communities to benefit from the implementation of support strategies. There is also a great need for educational programmes and capacity development within the two rural communities, particularly based on improved coping and longer-term adaptation strategies in response to climate change in order for households to better prepare themselves for the future.
- Full Text:
- Date Issued: 2013
Revision of Aloiampelos Klopper & Gideon F.Sm. (xanthorrhoeaceae subfam. asphodeloideae)
- Authors: Ellis, Kristen
- Date: 2013
- Subjects: Xanthorrhoeaceae , Asparagales
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10642 , http://hdl.handle.net/10948/d1020955
- Description: The genus Aloiampelos Klopper & Gideon F.Sm., previously treated as Aloe L. Ser. Macrifoliae (Sect. Prolongatae), comprises seven species with barely succulent leaves that are popularly known as rambling, scrambling or climbing aloes, because they make use of surrounding trees and shrubs for support. The rambling aloes are centered in the Eastern Cape but some species have disjunct distributions in the Western Cape and KwaZulu-Natal. Many are widely used in gardens and landscaping. With their rambling habit and weakly succulent leaves, the genus is widely considered to be an old lineage among alooid genera. Species concepts within the genus remain contentious, with disagreement amongst taxonomists with respect to the recognition of some taxa at the rank of variety. Morphology, historical taxonomy, palynology and phylogenetics of the genus were investigated. The occasional presence of minute cilia on the sheathing leaf bases and distinct lineation of the leaf sheaths of Aloiampelos tenuior var. decidua and Aloiampelos tenuior var. rubriflora were the most important outcomes of the morphological study. The pollen grains of all species studied were very similar in grain shape and exine surface pattern, with only minor differences in grain size. Ordination analyses showed that grain length and muri length were useful at the infraspecific level, with Aloiampelos tenuior “orange” separating clearly from the other varieties. Pollen morphology was therefore not informative as a taxonomic character at species level when used in isolation, but may be useful when used in conjunction with other characteristics. Preliminary analyses of two plastid barcoding regions (matK and rbcL) and nuclear ITS have confirmed that Aloiampelos is monophyletic. These barcoding markers were not informative in assessing the species boundaries among the closely related taxa in the genus and morphological assessments were therefore used to elucidate relationships at the species rank. A key is given for the genus, integrating the findings of the study.
- Full Text:
- Date Issued: 2013
- Authors: Ellis, Kristen
- Date: 2013
- Subjects: Xanthorrhoeaceae , Asparagales
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10642 , http://hdl.handle.net/10948/d1020955
- Description: The genus Aloiampelos Klopper & Gideon F.Sm., previously treated as Aloe L. Ser. Macrifoliae (Sect. Prolongatae), comprises seven species with barely succulent leaves that are popularly known as rambling, scrambling or climbing aloes, because they make use of surrounding trees and shrubs for support. The rambling aloes are centered in the Eastern Cape but some species have disjunct distributions in the Western Cape and KwaZulu-Natal. Many are widely used in gardens and landscaping. With their rambling habit and weakly succulent leaves, the genus is widely considered to be an old lineage among alooid genera. Species concepts within the genus remain contentious, with disagreement amongst taxonomists with respect to the recognition of some taxa at the rank of variety. Morphology, historical taxonomy, palynology and phylogenetics of the genus were investigated. The occasional presence of minute cilia on the sheathing leaf bases and distinct lineation of the leaf sheaths of Aloiampelos tenuior var. decidua and Aloiampelos tenuior var. rubriflora were the most important outcomes of the morphological study. The pollen grains of all species studied were very similar in grain shape and exine surface pattern, with only minor differences in grain size. Ordination analyses showed that grain length and muri length were useful at the infraspecific level, with Aloiampelos tenuior “orange” separating clearly from the other varieties. Pollen morphology was therefore not informative as a taxonomic character at species level when used in isolation, but may be useful when used in conjunction with other characteristics. Preliminary analyses of two plastid barcoding regions (matK and rbcL) and nuclear ITS have confirmed that Aloiampelos is monophyletic. These barcoding markers were not informative in assessing the species boundaries among the closely related taxa in the genus and morphological assessments were therefore used to elucidate relationships at the species rank. A key is given for the genus, integrating the findings of the study.
- Full Text:
- Date Issued: 2013
Rhenium (I), (III) and (V) complexes with potentially multidentate N, O-Donor ligands
- Authors: Habarurema, Gratien
- Date: 2013
- Subjects: Rhenium , Ligands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10441 , http://hdl.handle.net/10948/d1020952
- Description: This study investigates the coordination modes of potential multidentate N,O-donor Schiff base ligands to the [ReVO]3+ and fac-[ReI(CO)3]+ cores. The project is aimed at the synthesis of tridentate, tetradentate and pentadentate Schiff bases ligands derived from the condensation reactions of benzaldehyde with different primary amines. The structures of these Schiff bases and their complexes were confirmed by using physical characterization methods, namely melting points, UV-Visible, UV-emission, 1H NMR and IR spectroscopy, X-ray diffractometry and elemental analysis. To further understand the coordination chemistry of rhenium, the prepared diiminediphenol N2O2-donor Schiff base ligand N N′-o-phenylene-bis(salicylaldimine) (H2salphen) was reacted with trans-[ReOCl3(PPh3)2] to yield cis-[ReCl2(ophsal)(PPh3)], whereas its reaction with trans-[ReOBr3(PPh3)2] resulted in the formation of the cis-[ReBr2(aphsal)(PPh3)].2CH3CN complex. In the above complexes the H2salphen ligand was cleaved leading to the coordinated tridentate ophsal NO2- and aphsal N2O-donor ligands. The reaction of H3aphsal with trans-[ReOBr3(PPh3)2] in toluene led to an unexpected compound, trans- [{[ReBr(aphsal)(PPh3)2]Br}{[ReBr(aphsal)(PPh3)2](ReO4)}] with an imido [ReNR]3+core. The ligand aphsal was coordinated tridentately with the doubly deprotonated amino nitrogen leading to Re(V)-imido complexes. The reaction of 2-((Z)-(2-aminoethylimino)methyl)phenol (H3amphol) with [Re(CO)5Cl] led to the rhenium(I) product fac-[Re(CO)3(H3amphol)] with H3amphol coordinated as a monoanionic tridentate chelate through its phenolate oxygen and amino nitrogen atoms. The X-ray crystal structures showed that all complexes display a distorted octahedral geometry around the central rhenium atom. The reaction of 2,6-bis(2-hydroxyphenylimino)pyridine (H2hpp) with cis-[ReO2I(PPh3)2] resulted in the reduced Re(III) product trans-[Re(hpp)(PPh3)2]I, while trans-[Re(hpp)(PPh3)2](ReO4) was isolated from its reaction with trans-[ReOCl3(PPh3)2]. The H2hpp ligand acts as a pentadentate N3O2-donor ligand where the two phenolic protons undergo deprotonation and its three nitrogens act as neutral donor atoms. Both compounds resulted from a disproportionation reaction characterized by the produced perrhenate counter-ion. The complex fac-[Re(CO)3(H2hpp)Cl] was prepared from [Re(CO)5Cl] and H2hpp in toluene. The H2hpp ligand acted as a neutral bidentate N,N-donor chelate. The metal is coordinated to three carbonyl donors in a facial orientation, two neutral nitrogen atoms and a chloride ligand. The reactions of the potentially tetradentate ligand N,N'-ethylenebis(salicylideneimine) (H2salen) with different rhenium(V) precursors resulted in the formation of two dimeric oxorhenium (V) compounds. In the reaction of H2salen with trans-[ReOCl3(PPh3)2] in ethanol, the highly unusual distorted dimeric complex (μ-salen)[ReOCl2(PPh3)]2 was isolated, in which salen2- is coordinated as a tetradentate to two oxorhenium(V) centres, and salen2- is present as a bidentate monoanionic ligand on each rhenium center. The reaction of cis- [ReO2I(PPh3)2] with H2salen led to the formation of the neutral dimeric oxorhenium(V) complex (μ-O)[ReO(salen)]2 in which the tetradentate chelate salen acts as a tetradentate dianionic ligand through its phenolate oxygens and nitrogen atoms of the azomethine groups. In its reaction with H2hmp the compound (μ-O)[ReO(hmp)]2 was isolated. In this product the pentadentate ligand H2hmp coordinated as tetradentate via its phenolic oxygen and nitrogen atoms. The reaction of the potentially tetradentate N1,N2-bis(aminobenzylidene)-1,2-ethylenediamine (H2amben) with trans-[ReOCl3(PPh3)2] led to the formation of the monocationic square-pyramidal complex salt [ReO(amben)](ReO4.
- Full Text:
- Date Issued: 2013
- Authors: Habarurema, Gratien
- Date: 2013
- Subjects: Rhenium , Ligands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10441 , http://hdl.handle.net/10948/d1020952
- Description: This study investigates the coordination modes of potential multidentate N,O-donor Schiff base ligands to the [ReVO]3+ and fac-[ReI(CO)3]+ cores. The project is aimed at the synthesis of tridentate, tetradentate and pentadentate Schiff bases ligands derived from the condensation reactions of benzaldehyde with different primary amines. The structures of these Schiff bases and their complexes were confirmed by using physical characterization methods, namely melting points, UV-Visible, UV-emission, 1H NMR and IR spectroscopy, X-ray diffractometry and elemental analysis. To further understand the coordination chemistry of rhenium, the prepared diiminediphenol N2O2-donor Schiff base ligand N N′-o-phenylene-bis(salicylaldimine) (H2salphen) was reacted with trans-[ReOCl3(PPh3)2] to yield cis-[ReCl2(ophsal)(PPh3)], whereas its reaction with trans-[ReOBr3(PPh3)2] resulted in the formation of the cis-[ReBr2(aphsal)(PPh3)].2CH3CN complex. In the above complexes the H2salphen ligand was cleaved leading to the coordinated tridentate ophsal NO2- and aphsal N2O-donor ligands. The reaction of H3aphsal with trans-[ReOBr3(PPh3)2] in toluene led to an unexpected compound, trans- [{[ReBr(aphsal)(PPh3)2]Br}{[ReBr(aphsal)(PPh3)2](ReO4)}] with an imido [ReNR]3+core. The ligand aphsal was coordinated tridentately with the doubly deprotonated amino nitrogen leading to Re(V)-imido complexes. The reaction of 2-((Z)-(2-aminoethylimino)methyl)phenol (H3amphol) with [Re(CO)5Cl] led to the rhenium(I) product fac-[Re(CO)3(H3amphol)] with H3amphol coordinated as a monoanionic tridentate chelate through its phenolate oxygen and amino nitrogen atoms. The X-ray crystal structures showed that all complexes display a distorted octahedral geometry around the central rhenium atom. The reaction of 2,6-bis(2-hydroxyphenylimino)pyridine (H2hpp) with cis-[ReO2I(PPh3)2] resulted in the reduced Re(III) product trans-[Re(hpp)(PPh3)2]I, while trans-[Re(hpp)(PPh3)2](ReO4) was isolated from its reaction with trans-[ReOCl3(PPh3)2]. The H2hpp ligand acts as a pentadentate N3O2-donor ligand where the two phenolic protons undergo deprotonation and its three nitrogens act as neutral donor atoms. Both compounds resulted from a disproportionation reaction characterized by the produced perrhenate counter-ion. The complex fac-[Re(CO)3(H2hpp)Cl] was prepared from [Re(CO)5Cl] and H2hpp in toluene. The H2hpp ligand acted as a neutral bidentate N,N-donor chelate. The metal is coordinated to three carbonyl donors in a facial orientation, two neutral nitrogen atoms and a chloride ligand. The reactions of the potentially tetradentate ligand N,N'-ethylenebis(salicylideneimine) (H2salen) with different rhenium(V) precursors resulted in the formation of two dimeric oxorhenium (V) compounds. In the reaction of H2salen with trans-[ReOCl3(PPh3)2] in ethanol, the highly unusual distorted dimeric complex (μ-salen)[ReOCl2(PPh3)]2 was isolated, in which salen2- is coordinated as a tetradentate to two oxorhenium(V) centres, and salen2- is present as a bidentate monoanionic ligand on each rhenium center. The reaction of cis- [ReO2I(PPh3)2] with H2salen led to the formation of the neutral dimeric oxorhenium(V) complex (μ-O)[ReO(salen)]2 in which the tetradentate chelate salen acts as a tetradentate dianionic ligand through its phenolate oxygens and nitrogen atoms of the azomethine groups. In its reaction with H2hmp the compound (μ-O)[ReO(hmp)]2 was isolated. In this product the pentadentate ligand H2hmp coordinated as tetradentate via its phenolic oxygen and nitrogen atoms. The reaction of the potentially tetradentate N1,N2-bis(aminobenzylidene)-1,2-ethylenediamine (H2amben) with trans-[ReOCl3(PPh3)2] led to the formation of the monocationic square-pyramidal complex salt [ReO(amben)](ReO4.
- Full Text:
- Date Issued: 2013
Role of home gardens in enhancing food security in rural and urban areas : a case study of Nkonkobe Municipality, Eastern Cape South Africa
- Authors: Mcata, Bongiwe
- Date: 2013
- Subjects: Food security -- South Africa -- Eastern Cape Gardening -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13105 , vital:39465
- Description: In South Africa, home gardens are an important source of food and nutrition. In both urban and rural areas, home gardens have been a traditional way of providing food and offer a great potential for improving household food security and alleviating micronutrient deficiencies. In the Eastern Cape Province which is the second largest province in South Africa, and is characterized by poverty, home gardens can help enhance household food security through direct access to nutritionally-rich fresh vegetables. Home gardens are also becoming an important source of food and income, especially for poor households, in both urban and rural areas. the province. The findings illustrates that livelihood diversification may not be relevant for household welfare in the case of South Africa. However promoting livelihood diversification remain imperative for household welfare in the South Africa in the long-run. It further illustrate that gender of head, education, access to electricity, home agriculture are imperative for the improvement of household welfare. Hence the study recommends policy relating to conditional granting of cash grant support, intensification of rural development programmes, education affordable and accessible at all level and support home stead or subsistence agriculture This study was carried out to investigate the role of home gardens in addressing household food security in urban and rural areas of Nkonkobe Municipality. The study also identified the factors affecting the ownership of home gardens and food security. Data was collected from 160 households from both the urban and rural areas of the Nkonkobe Municipality. These households were selected through the use of stratified random sampling. Data was collected by a questionnaire was administered through face-to-face interviews. Frequencies and means were used to describe the general characteristics of the households as well as ownership patterns of home gardens. In order to determine the factors that influence home gardens and food security among the sampled households, a binary logistic regression model was adopted. The results show that the statistically significant variables, at the 5percent level, on food security are total income and home garden ownership. Food security was measured using the dietary diversity score. Location, access to land and education significantly affect the ownership of home gardens positively. In view of the research findings, several policy proposals are suggested. These include greater investment in programmes such as Massive food projects, Siyazondla and related home garden initiatives. Household income can be improved by promoting more non-agricultural activities in order to ensure household food security.
- Full Text:
- Date Issued: 2013
- Authors: Mcata, Bongiwe
- Date: 2013
- Subjects: Food security -- South Africa -- Eastern Cape Gardening -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13105 , vital:39465
- Description: In South Africa, home gardens are an important source of food and nutrition. In both urban and rural areas, home gardens have been a traditional way of providing food and offer a great potential for improving household food security and alleviating micronutrient deficiencies. In the Eastern Cape Province which is the second largest province in South Africa, and is characterized by poverty, home gardens can help enhance household food security through direct access to nutritionally-rich fresh vegetables. Home gardens are also becoming an important source of food and income, especially for poor households, in both urban and rural areas. the province. The findings illustrates that livelihood diversification may not be relevant for household welfare in the case of South Africa. However promoting livelihood diversification remain imperative for household welfare in the South Africa in the long-run. It further illustrate that gender of head, education, access to electricity, home agriculture are imperative for the improvement of household welfare. Hence the study recommends policy relating to conditional granting of cash grant support, intensification of rural development programmes, education affordable and accessible at all level and support home stead or subsistence agriculture This study was carried out to investigate the role of home gardens in addressing household food security in urban and rural areas of Nkonkobe Municipality. The study also identified the factors affecting the ownership of home gardens and food security. Data was collected from 160 households from both the urban and rural areas of the Nkonkobe Municipality. These households were selected through the use of stratified random sampling. Data was collected by a questionnaire was administered through face-to-face interviews. Frequencies and means were used to describe the general characteristics of the households as well as ownership patterns of home gardens. In order to determine the factors that influence home gardens and food security among the sampled households, a binary logistic regression model was adopted. The results show that the statistically significant variables, at the 5percent level, on food security are total income and home garden ownership. Food security was measured using the dietary diversity score. Location, access to land and education significantly affect the ownership of home gardens positively. In view of the research findings, several policy proposals are suggested. These include greater investment in programmes such as Massive food projects, Siyazondla and related home garden initiatives. Household income can be improved by promoting more non-agricultural activities in order to ensure household food security.
- Full Text:
- Date Issued: 2013
Search engine poisoning and its prevalence in modern search engines
- Authors: Blaauw, Pieter
- Date: 2013
- Subjects: Web search engines Internet searching World Wide Web Malware (Computer software) Computer viruses Rootkits (Computer software) Spyware (Computer software)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4572 , http://hdl.handle.net/10962/d1002037
- Description: The prevalence of Search Engine Poisoning in trending topics and popular search terms on the web within search engines is investigated. Search Engine Poisoning is the act of manipulating search engines in order to display search results from websites infected with malware. Research done between February and August 2012, using both manual and automated techniques, shows us how easily the criminal element manages to insert malicious content into web pages related to popular search terms within search engines. In order to provide the reader with a clear overview and understanding of the motives and the methods of the operators of Search Engine Poisoning campaigns, an in-depth review of automated and semi-automated web exploit kits is done, as well as looking into the motives for running these campaigns. Three high profile case studies are examined, and the various Search Engine Poisoning campaigns associated with these case studies are discussed in detail to the reader. From February to August 2012, data was collected from the top trending topics on Google’s search engine along with the top listed sites related to these topics, and then passed through various automated tools to discover if these results have been infiltrated by the operators of Search Engine Poisoning campaings, and the results of these automated scans are then discussed in detail. During the research period, manual searching for Search Engine Poisoning campaigns was also done, using high profile news events and popular search terms. These results are analysed in detail to determine the methods of attack, the purpose of the attack and the parties behind it
- Full Text:
- Date Issued: 2013
- Authors: Blaauw, Pieter
- Date: 2013
- Subjects: Web search engines Internet searching World Wide Web Malware (Computer software) Computer viruses Rootkits (Computer software) Spyware (Computer software)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4572 , http://hdl.handle.net/10962/d1002037
- Description: The prevalence of Search Engine Poisoning in trending topics and popular search terms on the web within search engines is investigated. Search Engine Poisoning is the act of manipulating search engines in order to display search results from websites infected with malware. Research done between February and August 2012, using both manual and automated techniques, shows us how easily the criminal element manages to insert malicious content into web pages related to popular search terms within search engines. In order to provide the reader with a clear overview and understanding of the motives and the methods of the operators of Search Engine Poisoning campaigns, an in-depth review of automated and semi-automated web exploit kits is done, as well as looking into the motives for running these campaigns. Three high profile case studies are examined, and the various Search Engine Poisoning campaigns associated with these case studies are discussed in detail to the reader. From February to August 2012, data was collected from the top trending topics on Google’s search engine along with the top listed sites related to these topics, and then passed through various automated tools to discover if these results have been infiltrated by the operators of Search Engine Poisoning campaings, and the results of these automated scans are then discussed in detail. During the research period, manual searching for Search Engine Poisoning campaigns was also done, using high profile news events and popular search terms. These results are analysed in detail to determine the methods of attack, the purpose of the attack and the parties behind it
- Full Text:
- Date Issued: 2013
Selected physiological and perceptual responses of batsmen during a simulated one day international century : impact on performance
- Authors: Pote, Lee
- Date: 2013 , 2013-04-02
- Subjects: Cricket -- Batting , Sports -- Physiological aspects , Sports -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5097 , http://hdl.handle.net/10962/d1001650
- Description: Background: Very few studies have examined the demands of prolonged batting on physical, psychophysical and performance responses. Objective: The purpose of this study was therefore to determine the physiological and perceptual responses of batsmen scoring a simulated One Day International century. Furthermore, the impact that these responses had on batting performance were also measured. Methods: Seventeen male cricketers currently playing for Rhodes University or the country districts side, performed a simulated bating innings (BATEX©), typical of scoring a One Day international century. The BATEX© protocol consisted of six, five over stages (21 minutes each), with each stage matched to a specific phase of play where batsmen were encouraged to bat with the mindset of that phase. During stages one, three and five players ran at a “self-selected cruise pace” whereas during stages two, four and six players were required to run at maximum speed. At set intervals, selected physiological, perceptual and performance measures were recorded. Results: Most physiological responses increased and decreased accordingly with the low and high intensity stages with the exception of respiratory exchange ratio and core temperature responses. Mean physiological responses however, showed a progressive rise over time. Central ratings of perceived exertion increased as a function of intensity and duration. Sprint times got slower as the protocol progressed, while accuracy (impact accuracy) improved significantly (p<0.05) after stage one and then stabilised for the remainder of the protocol. Conclusion: The simulated batting protocol significantly impacted the physiological and perceptual responses over time. This was due to both the intensity and the duration of the work-bout. Furthermore, the increased physiological load placed on the batsmen significantly impacted the physical performance of the batsmen. An increase in sprint times (players getting slower) towards the end of the protocol may indicate the presence of physical fatigue. This physical fatigue did not however seem to impact the batsmen cognitively as accuracy improved after the first stage and then remained constant over time.
- Full Text:
- Date Issued: 2013
- Authors: Pote, Lee
- Date: 2013 , 2013-04-02
- Subjects: Cricket -- Batting , Sports -- Physiological aspects , Sports -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5097 , http://hdl.handle.net/10962/d1001650
- Description: Background: Very few studies have examined the demands of prolonged batting on physical, psychophysical and performance responses. Objective: The purpose of this study was therefore to determine the physiological and perceptual responses of batsmen scoring a simulated One Day International century. Furthermore, the impact that these responses had on batting performance were also measured. Methods: Seventeen male cricketers currently playing for Rhodes University or the country districts side, performed a simulated bating innings (BATEX©), typical of scoring a One Day international century. The BATEX© protocol consisted of six, five over stages (21 minutes each), with each stage matched to a specific phase of play where batsmen were encouraged to bat with the mindset of that phase. During stages one, three and five players ran at a “self-selected cruise pace” whereas during stages two, four and six players were required to run at maximum speed. At set intervals, selected physiological, perceptual and performance measures were recorded. Results: Most physiological responses increased and decreased accordingly with the low and high intensity stages with the exception of respiratory exchange ratio and core temperature responses. Mean physiological responses however, showed a progressive rise over time. Central ratings of perceived exertion increased as a function of intensity and duration. Sprint times got slower as the protocol progressed, while accuracy (impact accuracy) improved significantly (p<0.05) after stage one and then stabilised for the remainder of the protocol. Conclusion: The simulated batting protocol significantly impacted the physiological and perceptual responses over time. This was due to both the intensity and the duration of the work-bout. Furthermore, the increased physiological load placed on the batsmen significantly impacted the physical performance of the batsmen. An increase in sprint times (players getting slower) towards the end of the protocol may indicate the presence of physical fatigue. This physical fatigue did not however seem to impact the batsmen cognitively as accuracy improved after the first stage and then remained constant over time.
- Full Text:
- Date Issued: 2013
Sequence and structural investigation of the nonribosomal peptide synthetases of Bacillus atrophaeus UCMB 5137(63Z)
- Authors: Ryan, Candice Nancy
- Date: 2013 , 2013-04-19
- Subjects: Bacillus (Bacteria) , Peptides--Synthesis , Antibiotics , Drug resistance in microorganisms , Amino acids , Phytopathogenic microorganisms , Trees--Phylogeny , Ligases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3891 , http://hdl.handle.net/10962/d1003057 , Bacillus (Bacteria) , Peptides--Synthesis , Antibiotics , Drug resistance in microorganisms , Amino acids , Phytopathogenic microorganisms , Trees--Phylogeny , Ligases
- Description: Due to increased plant resistance to the existing antibiotics produced, there is a need to develop alternatives. Nonribosomal peptides (NRPs) are important plant phytopathogens synthesized by nonribosomal peptide synthetases (NRPSs). In this study, a newly sequenced Bacillus strain Bacillus atrophaeus UCMB 5137 (63Z), found to have increased phytopathogenic activity, was investigated to gain insights to the possible reason behind this activity. NRPS modules were identified using a novel script that can act on unannotated, raw DNA sequences. The Structure Based Sequence Analysis Webserver was used to identify the amino acids incorporated into the final NRP, which were compared to the NRP database. Five NRPSs were found within the strain; fengycin/plipstatin, mycosubtilin, surfactin, bacillibactin and bacitracin. Some of the modules usually present for these NRPSs were not present in the test strain and only a few modules were found. A phylogenetic study was carried out and the topologies of the trees showed that genes were not transferred horizontally. It did, however, lead to the hypothesis that different NRPS genes are under different adaptive evolutionary pressures. Only slight conformational changes between L and D-conformation of amino acids were seen between the test and neighboring strains. All of the linker and terminal regions of synthetases were found to exhibit a large amount of conservation overall. Homology modeling was performed on the test strain on selected modules, TE and A-domains of fengycin and mycosubtilin synthetases. TE-domains between the different synthetases are different and specific for the NRP they facilitate release for. The NRPS from which the A-domain originates also influences substrate specificity as well as the module in which the A-domain occurs within the NRPS. Binding pockets of A-domains of differing substrate specificity were compared. Future work will include; refinement of the models and docking studies within the A-domain binding pocket. , Microsoft� Word 2010 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Ryan, Candice Nancy
- Date: 2013 , 2013-04-19
- Subjects: Bacillus (Bacteria) , Peptides--Synthesis , Antibiotics , Drug resistance in microorganisms , Amino acids , Phytopathogenic microorganisms , Trees--Phylogeny , Ligases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3891 , http://hdl.handle.net/10962/d1003057 , Bacillus (Bacteria) , Peptides--Synthesis , Antibiotics , Drug resistance in microorganisms , Amino acids , Phytopathogenic microorganisms , Trees--Phylogeny , Ligases
- Description: Due to increased plant resistance to the existing antibiotics produced, there is a need to develop alternatives. Nonribosomal peptides (NRPs) are important plant phytopathogens synthesized by nonribosomal peptide synthetases (NRPSs). In this study, a newly sequenced Bacillus strain Bacillus atrophaeus UCMB 5137 (63Z), found to have increased phytopathogenic activity, was investigated to gain insights to the possible reason behind this activity. NRPS modules were identified using a novel script that can act on unannotated, raw DNA sequences. The Structure Based Sequence Analysis Webserver was used to identify the amino acids incorporated into the final NRP, which were compared to the NRP database. Five NRPSs were found within the strain; fengycin/plipstatin, mycosubtilin, surfactin, bacillibactin and bacitracin. Some of the modules usually present for these NRPSs were not present in the test strain and only a few modules were found. A phylogenetic study was carried out and the topologies of the trees showed that genes were not transferred horizontally. It did, however, lead to the hypothesis that different NRPS genes are under different adaptive evolutionary pressures. Only slight conformational changes between L and D-conformation of amino acids were seen between the test and neighboring strains. All of the linker and terminal regions of synthetases were found to exhibit a large amount of conservation overall. Homology modeling was performed on the test strain on selected modules, TE and A-domains of fengycin and mycosubtilin synthetases. TE-domains between the different synthetases are different and specific for the NRP they facilitate release for. The NRPS from which the A-domain originates also influences substrate specificity as well as the module in which the A-domain occurs within the NRPS. Binding pockets of A-domains of differing substrate specificity were compared. Future work will include; refinement of the models and docking studies within the A-domain binding pocket. , Microsoft� Word 2010 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
Social network analysis of stakeholders in the Duiwenhoks Water Catchment
- Authors: Whyte, Michelle
- Date: 2013
- Subjects: Conservation of natural resources -- South Africa , Conservation plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10756 , http://hdl.handle.net/10948/d1020995
- Description: Social-ecological systems are facing complex social, political, economic and environmental problems beyond the capacity of one group of stakeholders or organization to solve in isolation. Ecosystem degradation causes major environmental and economic concern, due to the loss of ecosystem services which river and wetland ecosystems provide. Stakeholder communities who depend on natural resources need to identify the social processes which are underlying causes to unsuccessful natural resource management and thus environmental degradation. The study is primarily aimed at identifying and understanding the structural and functional properties of the stakeholder network in the Duiwenhoks River catchment in the Western Cape, South Africa. Through analyzing the social network properties the study identifies and describes the main stakeholders involved with natural resource management in the Duiwenhoks water catchment area. How the individual actors from the diverse stakeholder groups are connected through communication ties were assessed. Furthermore, issues and factors which limit the effectiveness of the social network were identified. The main factors include a lack of communication and collaboration between key local resource users and governance officials caused by conflicting perspectives regarding resource management and societal conflicts caused by asymmetries in power distribution favoring government institutions. The lack of collaboration between stakeholders was identified as a contributing factor that links to the resource degradation experienced in the catchment. Ultimately means of overcoming the limitations to effective social networking, in order to manage the challenges related to natural resource management were identified. Management recommendations include the development of bridging ties and collaboration between diverse stakeholders, whilst facilitating participatory processes aimed at participatory problem solving and adaptive co-management of natural resources. Government institutions were identified as being dominant stakeholders in the network and should be mobilized to perform a stronger bridging role to connect disconnected actors. The findings of the study may inform future efforts of researchers and facilitators to implement strategies which promote social networking, social learning and ultimately adaptive co-management in the study area or other similar social-ecological systems. Ultimately, collaboration can be achieved between the diverse stakeholders to successfully improve ecosystem management and resilience in the Duiwenhoks water catchment.
- Full Text:
- Date Issued: 2013
- Authors: Whyte, Michelle
- Date: 2013
- Subjects: Conservation of natural resources -- South Africa , Conservation plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10756 , http://hdl.handle.net/10948/d1020995
- Description: Social-ecological systems are facing complex social, political, economic and environmental problems beyond the capacity of one group of stakeholders or organization to solve in isolation. Ecosystem degradation causes major environmental and economic concern, due to the loss of ecosystem services which river and wetland ecosystems provide. Stakeholder communities who depend on natural resources need to identify the social processes which are underlying causes to unsuccessful natural resource management and thus environmental degradation. The study is primarily aimed at identifying and understanding the structural and functional properties of the stakeholder network in the Duiwenhoks River catchment in the Western Cape, South Africa. Through analyzing the social network properties the study identifies and describes the main stakeholders involved with natural resource management in the Duiwenhoks water catchment area. How the individual actors from the diverse stakeholder groups are connected through communication ties were assessed. Furthermore, issues and factors which limit the effectiveness of the social network were identified. The main factors include a lack of communication and collaboration between key local resource users and governance officials caused by conflicting perspectives regarding resource management and societal conflicts caused by asymmetries in power distribution favoring government institutions. The lack of collaboration between stakeholders was identified as a contributing factor that links to the resource degradation experienced in the catchment. Ultimately means of overcoming the limitations to effective social networking, in order to manage the challenges related to natural resource management were identified. Management recommendations include the development of bridging ties and collaboration between diverse stakeholders, whilst facilitating participatory processes aimed at participatory problem solving and adaptive co-management of natural resources. Government institutions were identified as being dominant stakeholders in the network and should be mobilized to perform a stronger bridging role to connect disconnected actors. The findings of the study may inform future efforts of researchers and facilitators to implement strategies which promote social networking, social learning and ultimately adaptive co-management in the study area or other similar social-ecological systems. Ultimately, collaboration can be achieved between the diverse stakeholders to successfully improve ecosystem management and resilience in the Duiwenhoks water catchment.
- Full Text:
- Date Issued: 2013
South African anthropometric dimensions for the design of an ergonomic office chair
- Authors: Korte, Janice
- Date: 2013 , 2013-09-05
- Subjects: Design -- Human factors , Office chairs , Chair design , Human engineering , Sitting position
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5137 , http://hdl.handle.net/10962/d1006046 , Design -- Human factors , Office chairs , Chair design , Human engineering , Sitting position
- Description: Office chairs are becoming a modern status symbol in the workplace. Many individuals are seated on office chairs for most of the working day. As a result of using poorly designed chairs injury and discomfort are frequently experienced, most particularly lower back pain. Correct design of chairs is imperative, and must be user-centered. The aim of this investigation has been to gather anthropometric dimensions characteristic of the South African population, as this information has not been widely assimilated to date. Once collated, this information could be used in the design of an ergonomically correct office chair, suitable for the unique characteristics of the South African working population. Anthropometric dimensions were collected from 683 South Africans (comprising 448 South African females and 235 South African males) from pre-selected companies in major centres in South Africa (Johannesburg, Pietermaritzburg, Durban, East London, Grahamstown, Port Elizabeth and Cape Town). Measurements included participants’ personal information (age, sex, home language and ethnic group), basic anthropometric measures (stature, shoulder height, mass, and waist and hip circumference) as well as specific measures of fit of the individual to the specially designed, adjustable chair. Of the 448 females, 317 were Black females, 77 were White females, 35 were Coloured females and 19 were Indian/Asian females. Of the 235 males, 112 were Black males, 79 were White males, 26 were Coloured males and 18 were Indian/Asian males. Office chair dimensions for each ethnic group were represented and differences were noted. A comparison between a current office chair’s dimensions and the South African sample office chair’s dimensions indicated modifications that would need to be constructed to suit the South African sample. The conventional office chair is still the most widely accepted office chair due to its stability and support structures that maintain the correct sitting posture of the user. An ergonomic office chair needs to incorporate anthropometric dimensions worldwide.
- Full Text:
- Date Issued: 2013
- Authors: Korte, Janice
- Date: 2013 , 2013-09-05
- Subjects: Design -- Human factors , Office chairs , Chair design , Human engineering , Sitting position
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5137 , http://hdl.handle.net/10962/d1006046 , Design -- Human factors , Office chairs , Chair design , Human engineering , Sitting position
- Description: Office chairs are becoming a modern status symbol in the workplace. Many individuals are seated on office chairs for most of the working day. As a result of using poorly designed chairs injury and discomfort are frequently experienced, most particularly lower back pain. Correct design of chairs is imperative, and must be user-centered. The aim of this investigation has been to gather anthropometric dimensions characteristic of the South African population, as this information has not been widely assimilated to date. Once collated, this information could be used in the design of an ergonomically correct office chair, suitable for the unique characteristics of the South African working population. Anthropometric dimensions were collected from 683 South Africans (comprising 448 South African females and 235 South African males) from pre-selected companies in major centres in South Africa (Johannesburg, Pietermaritzburg, Durban, East London, Grahamstown, Port Elizabeth and Cape Town). Measurements included participants’ personal information (age, sex, home language and ethnic group), basic anthropometric measures (stature, shoulder height, mass, and waist and hip circumference) as well as specific measures of fit of the individual to the specially designed, adjustable chair. Of the 448 females, 317 were Black females, 77 were White females, 35 were Coloured females and 19 were Indian/Asian females. Of the 235 males, 112 were Black males, 79 were White males, 26 were Coloured males and 18 were Indian/Asian males. Office chair dimensions for each ethnic group were represented and differences were noted. A comparison between a current office chair’s dimensions and the South African sample office chair’s dimensions indicated modifications that would need to be constructed to suit the South African sample. The conventional office chair is still the most widely accepted office chair due to its stability and support structures that maintain the correct sitting posture of the user. An ergonomic office chair needs to incorporate anthropometric dimensions worldwide.
- Full Text:
- Date Issued: 2013
Spatial and temporal patterns in the population and the feeding of Palaemon peringueyi (MacPherson 1990) (Decapoda, Palaemonidae) in the Kariega estuary, South Africa
- Nyalungu, Nonhlanhla Precotia Dudu
- Authors: Nyalungu, Nonhlanhla Precotia Dudu
- Date: 2013
- Subjects: Palaemonidae -- Food -- South Africa , Palaemonidae -- Behavior -- South Africa , Palaemonidae -- Habitat -- South Africa , Estuarine biology -- South Africa , Shrimp populations -- South Africa , Shrimps -- South Africa , Decapoda (Crustacea) -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5584 , http://hdl.handle.net/10962/d1001576 , Palaemonidae -- Food -- South Africa , Palaemonidae -- Behavior -- South Africa , Palaemonidae -- Habitat -- South Africa , Estuarine biology -- South Africa , Shrimp populations -- South Africa , Shrimps -- South Africa , Decapoda (Crustacea) -- South Africa
- Description: The spatial and temporal patterns in the population demographs and feeding ecology of the caridean shrimp, Palaemon peringueyi, was investigated over a 12 month period in the permanently open Kariega Estuary situated on the south-east coastline of South Africa. Shrimps were sampled monthly from three stations corresponding to the lower, middle and upper reaches of the Kariega Estuary. The shrimps were collected at the different stations using a pull net. Temperature, salinity, dissolved oxygen and % cover of submerged vegetation were measured at each sampling station. Finally, the feeding ecology of the shrimp was investigated employing stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes analysis. Temperature, salinity, dissolved oxygen and vegetation cover showed distinct seasonal patterns. The shrimps attained total abundances and biomass of between 0 and 245.6 individuals per m² (ind.m⁻²) and between 0 and 13.6 grams wet weight per m² (g wwt.m⁻²), respectively. Mean abundance ranged between 2.3 (± 3.0) and 88 (± 27.3) ind.m⁻² in the lower reach, between 0.9 (± 0.4) to 21.5 (± 4.5) ind.m⁻² in the middle reach and 0 to 1.6 (± 0.5) ind.m⁻² in the upper reach. Mean biomass ranged between 0.4 (± 0.5) and 4.4 (± 1.4) g wwt.m⁻² in the lower reach, between 0.1 (± 0) to 4.3 (± 0.9) g wwt.m⁻² in the middle reach and between 0 to 1.6 (± 0.5) g wwt.m⁻² in the upper reach. Greatest abundances and biomasses were recorded in winter following heavy rainfall within the catchment area. Freshwater inflow which is due to rainfall is thought to provide a cue for the recruitment of marine breeding organisms. The spatial patterns in the distribution of the shrimps showed that juveniles occupied the lower and middle reaches and adults the entire length of the estuary. There were no significant relationships between the abundance and biomass of the shrimps and the selected physico-chemical variables (p > 0.05 in all cases). Results of the stable isotope study indicated that the mean δ¹³C of the shrimps in the lower, middle and upper reaches were -12.4 (± 1.3) ‰, -15.6 (± 0.5) ‰ and -17.5 (± 0.5) ‰, respectively. The δ¹⁵N isotopes of the shrimps in the lower reach was 11.6 (± 0.5) ‰ with middle and upper reaches having similar δ¹⁵N values, 13.5 (± 0.4) ‰ and 13.4 (± 0.4) ‰, respectively. There was no significant difference in the δ¹³C and δ¹⁵N isotope (p > 0.05) between the sexes of the shrimps. Two-way ANOVA indicated a significant difference in the δ¹³C isotope of the shrimps between the sites (p < 0.05). The difference in the δ¹³C and δ¹⁵N ratios of the shrimps suggests spatial variability in the diet of P. peringueyi within the Kariega Estuary. The diet of the shrimps in the lower reach is primarily composed of Nanozostera capensis epibionts. In the middle reach the diet of the shrimps is likely comprised of the detritus of benthic algae. In the upper reach of the estuary, P. peringueyi likely derives its carbon from a combination of epibionts, benthic algae and detritus derived from Codium.
- Full Text:
- Date Issued: 2013
- Authors: Nyalungu, Nonhlanhla Precotia Dudu
- Date: 2013
- Subjects: Palaemonidae -- Food -- South Africa , Palaemonidae -- Behavior -- South Africa , Palaemonidae -- Habitat -- South Africa , Estuarine biology -- South Africa , Shrimp populations -- South Africa , Shrimps -- South Africa , Decapoda (Crustacea) -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5584 , http://hdl.handle.net/10962/d1001576 , Palaemonidae -- Food -- South Africa , Palaemonidae -- Behavior -- South Africa , Palaemonidae -- Habitat -- South Africa , Estuarine biology -- South Africa , Shrimp populations -- South Africa , Shrimps -- South Africa , Decapoda (Crustacea) -- South Africa
- Description: The spatial and temporal patterns in the population demographs and feeding ecology of the caridean shrimp, Palaemon peringueyi, was investigated over a 12 month period in the permanently open Kariega Estuary situated on the south-east coastline of South Africa. Shrimps were sampled monthly from three stations corresponding to the lower, middle and upper reaches of the Kariega Estuary. The shrimps were collected at the different stations using a pull net. Temperature, salinity, dissolved oxygen and % cover of submerged vegetation were measured at each sampling station. Finally, the feeding ecology of the shrimp was investigated employing stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes analysis. Temperature, salinity, dissolved oxygen and vegetation cover showed distinct seasonal patterns. The shrimps attained total abundances and biomass of between 0 and 245.6 individuals per m² (ind.m⁻²) and between 0 and 13.6 grams wet weight per m² (g wwt.m⁻²), respectively. Mean abundance ranged between 2.3 (± 3.0) and 88 (± 27.3) ind.m⁻² in the lower reach, between 0.9 (± 0.4) to 21.5 (± 4.5) ind.m⁻² in the middle reach and 0 to 1.6 (± 0.5) ind.m⁻² in the upper reach. Mean biomass ranged between 0.4 (± 0.5) and 4.4 (± 1.4) g wwt.m⁻² in the lower reach, between 0.1 (± 0) to 4.3 (± 0.9) g wwt.m⁻² in the middle reach and between 0 to 1.6 (± 0.5) g wwt.m⁻² in the upper reach. Greatest abundances and biomasses were recorded in winter following heavy rainfall within the catchment area. Freshwater inflow which is due to rainfall is thought to provide a cue for the recruitment of marine breeding organisms. The spatial patterns in the distribution of the shrimps showed that juveniles occupied the lower and middle reaches and adults the entire length of the estuary. There were no significant relationships between the abundance and biomass of the shrimps and the selected physico-chemical variables (p > 0.05 in all cases). Results of the stable isotope study indicated that the mean δ¹³C of the shrimps in the lower, middle and upper reaches were -12.4 (± 1.3) ‰, -15.6 (± 0.5) ‰ and -17.5 (± 0.5) ‰, respectively. The δ¹⁵N isotopes of the shrimps in the lower reach was 11.6 (± 0.5) ‰ with middle and upper reaches having similar δ¹⁵N values, 13.5 (± 0.4) ‰ and 13.4 (± 0.4) ‰, respectively. There was no significant difference in the δ¹³C and δ¹⁵N isotope (p > 0.05) between the sexes of the shrimps. Two-way ANOVA indicated a significant difference in the δ¹³C isotope of the shrimps between the sites (p < 0.05). The difference in the δ¹³C and δ¹⁵N ratios of the shrimps suggests spatial variability in the diet of P. peringueyi within the Kariega Estuary. The diet of the shrimps in the lower reach is primarily composed of Nanozostera capensis epibionts. In the middle reach the diet of the shrimps is likely comprised of the detritus of benthic algae. In the upper reach of the estuary, P. peringueyi likely derives its carbon from a combination of epibionts, benthic algae and detritus derived from Codium.
- Full Text:
- Date Issued: 2013
Stable isotopes dynamics of macrophytes along Umtata River in the Eastern Cape of South Africa
- Authors: Mzamo, Sanele Caleb
- Date: 2013
- Subjects: Stable isotopes -- Macrophytes , South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:18485 , http://hdl.handle.net/11260/d1007205
- Description: The decline of freshwater ecosystems, generally result from land use activities in the river catchment and is of great concern worldwide. This study was conducted along Umtata River in the Eastern Cape province of South Africa between May 2010 and April 2011. The study was aimed at identifying macrophytes families (to species level) and determining the stable isotope signatures (C:N ratios, δ13C and δ15N) and to relate their isotopic signatures to the land use activities along the river catchment. Analysis of variance was performed to test the effect of sites and sampling period on the C:N ratios, δ13C and δ15N signatures. There were 16 macrophyte families represented by 26 species recorded along the river. There was only a significant difference in sites and sampling period in δ15N (p< 0.05). The highest C:N ratios value (30.75±9.65‰) was recorded in the upper reaches while the lowest value (6.10±2.35‰) occurred in the lower reaches. The δ13C values varied throughout the length of the river with highest values (-19.63±5.44‰) obtained in the middle reaches. Spatial variation was evident in δ15N throughout the length of the river and showed increase from the upper reaches to middle reaches and decreased towards lower reaches. The δ15N ranged from 3.92±2.43‰ in the upper reaches to 10.02±4.56‰ in the middle reaches. Temporal variation in δ15N was also evident throughout the sampling period with highest peak in May (9.77± 4.49‰) and lowest in February (0.50±2.49‰) respectively. The highest values of isotope signatures at spatial level demonstrated the true reflection of urban development, sewage discharge and agricultural activities taking place along the river system. Continued monitoring is recommended that may ultimately come up with a better management options for the communities living within the study area, and also to better enhanced land utilization.
- Full Text:
- Date Issued: 2013
- Authors: Mzamo, Sanele Caleb
- Date: 2013
- Subjects: Stable isotopes -- Macrophytes , South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:18485 , http://hdl.handle.net/11260/d1007205
- Description: The decline of freshwater ecosystems, generally result from land use activities in the river catchment and is of great concern worldwide. This study was conducted along Umtata River in the Eastern Cape province of South Africa between May 2010 and April 2011. The study was aimed at identifying macrophytes families (to species level) and determining the stable isotope signatures (C:N ratios, δ13C and δ15N) and to relate their isotopic signatures to the land use activities along the river catchment. Analysis of variance was performed to test the effect of sites and sampling period on the C:N ratios, δ13C and δ15N signatures. There were 16 macrophyte families represented by 26 species recorded along the river. There was only a significant difference in sites and sampling period in δ15N (p< 0.05). The highest C:N ratios value (30.75±9.65‰) was recorded in the upper reaches while the lowest value (6.10±2.35‰) occurred in the lower reaches. The δ13C values varied throughout the length of the river with highest values (-19.63±5.44‰) obtained in the middle reaches. Spatial variation was evident in δ15N throughout the length of the river and showed increase from the upper reaches to middle reaches and decreased towards lower reaches. The δ15N ranged from 3.92±2.43‰ in the upper reaches to 10.02±4.56‰ in the middle reaches. Temporal variation in δ15N was also evident throughout the sampling period with highest peak in May (9.77± 4.49‰) and lowest in February (0.50±2.49‰) respectively. The highest values of isotope signatures at spatial level demonstrated the true reflection of urban development, sewage discharge and agricultural activities taking place along the river system. Continued monitoring is recommended that may ultimately come up with a better management options for the communities living within the study area, and also to better enhanced land utilization.
- Full Text:
- Date Issued: 2013
Statistical analysis of electricity demand profiles
- Authors: Mangisa, Siphumlile
- Date: 2013
- Subjects: Electric power consumption -- Forecasting , Energy consumption , Electric power consumption
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10572 , http://hdl.handle.net/10948/d1011548 , Electric power consumption -- Forecasting , Energy consumption , Electric power consumption
- Description: An electricity demand profile is a graph showing the amount of electricity used by customers over a unit of time. It shows the variation in electricity demand versus time. In the demand profiles, the shape of the graph is of utmost importance. The variations in demand profiles are caused by many factors, such as economic and en- vironmental factors. These variations may also be due to changes in the electricity use behaviours of electricity users. This study seeks to model daily profiles of energy demand in South Africa with a model which is a composition of two de Moivre type models. The model has seven parameters, each with a natural interpretation (one parameter representing minimum demand in a day, two parameters representing the time of morning and afternoon peaks, two parameters representing the shape of each peak, and two parameters representing the total energy per peak). With the help of this model, we trace change in the demand profile over a number of years. The proposed model will be helpful for short to long term electricity demand forecasting.
- Full Text:
- Date Issued: 2013
- Authors: Mangisa, Siphumlile
- Date: 2013
- Subjects: Electric power consumption -- Forecasting , Energy consumption , Electric power consumption
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10572 , http://hdl.handle.net/10948/d1011548 , Electric power consumption -- Forecasting , Energy consumption , Electric power consumption
- Description: An electricity demand profile is a graph showing the amount of electricity used by customers over a unit of time. It shows the variation in electricity demand versus time. In the demand profiles, the shape of the graph is of utmost importance. The variations in demand profiles are caused by many factors, such as economic and en- vironmental factors. These variations may also be due to changes in the electricity use behaviours of electricity users. This study seeks to model daily profiles of energy demand in South Africa with a model which is a composition of two de Moivre type models. The model has seven parameters, each with a natural interpretation (one parameter representing minimum demand in a day, two parameters representing the time of morning and afternoon peaks, two parameters representing the shape of each peak, and two parameters representing the total energy per peak). With the help of this model, we trace change in the demand profile over a number of years. The proposed model will be helpful for short to long term electricity demand forecasting.
- Full Text:
- Date Issued: 2013