Identification of differentially expressed proteins involved in wheat (Triticum aestivum) resistance against Russian Wheat Aphid (Diuraphis noxia) SA2 using SWATH-MS analysis
- Authors: Ntlokwana, Sitha Emmanuel
- Date: 2020
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18872 , vital:42888
- Description: Wheat (Triticum aestivum) is the second most-consumed cereal crop in the world, second only to maize. In South Africa it is mainly produced in three provinces; the Free State, Western Cape, and the Northen Cape. The average total land area used for wheat cultivation in these three Provinces, is 533 000 hectares, with a resultant annual production of between 1.3 to 2 million tons. The total wheat requirement in South Africa is currently 2.7 million tons according to the production of wheat guidelines published by the Department of Agriculture, Forestry and Fisheries, which is higher than the total annual production. One of the primary reasons that contribute to the lower production levels is insect and pest infestation, in particular, the Russian wheat aphid (Diurophis noxis), which can result in crop loss of up to sixty percent. Russian wheat aphids (RWA) are invasive insects that feed on the phloem of the plant through their specialised thin stylet-like mouthparts and release toxic agents contained in their saliva during feeding, which disrupt cellular functions inside the host plant. This damage leads to symptoms like; chlorosis, necrosis, wilting, stunting and curling of leaves, also known as leaf rolling. This study aimed to identify differentially expressed proteins in resistant and susceptible wheat (Triticum aestivum) cultivars during Russian wheat aphid Biotype South African 2 (RWA-SA2) infestation, in order to identify proteins involved in the wheat resistant mechanism against RWA-SA2. Two wheat cultivars SST398 (resistant to RWA-SA2) and SST356 (susceptible to RWA-SA2) were used, and a total number of 126 plants were planted and divided according to four different harvest times (Control day 0; day 5; day 7 and day 12). The wheat plants were infested with approximately 10 aphids per plant at the three-leaf stage, and placed within an insect cage inside a growth chamber (Conviron, Winnipeg, Canada) set at 24ºC, light intensity of 352 µmol.m-2.sec-1, ambient CO2 levels (410 ppm) and humidity of 60% with a 16h/8h day/night cycle. Wheat leaves were harvested at various time frames, and total protein extraction was performed. The protein samples were reduced with 10 mM dithiothreitol (DTT) and alkylated with 30 mM iodoacetamide (IAA). Sample clean-up and on-bead trypsin digest were performed on megReSyn Hilic columns, over four hours. The resultant peptides were vacuum dried and resuspended in 2% acetonitrile (ACN) before submitting them to LC-MS/MS (SWATH) for analysis. A total number of 611 proteins were differentially expressed, of which 19 were identified to be involved in the resistance response of wheat, and an additional 20 involved in biotic stress responses. This study showed that reactive oxidative species (ROS) such as hydrogen peroxide and hydroxyl radicals (OH-) play a significant role in the early stages of wheat resistance against RWA-SA2 infestation. They are involved in cell wall strengthening, activation of defence genes, involvement of phytohormone signals such as salicylic and jasmonic acid, which also mediates the systemic defences such as, systemic acquired resistance (SAR), leading to the expression of pathogen-related proteins such as (thaumatin-like proteins, oxalate oxidase, defensin, chitinase, and thionins). Although up-regulation of photosynthesis proteins such as (chlorophyll a/b binding protein, photosystem I and II, rubisco and divinyl chlorophyllide a, and 8 vinyl-reductase) were seen on both infested cultivars (susceptible and resistance), higher numbers of these classes of proteins were identified in the resistance cultivar, suggesting that they also play a critical role in resistance. In conclusion, the SWATH analysis used in this study was able to identify numerous proteins involved in the wheat resistance mechanism against RWA-SA2, most of which have not yet been reported to be involved in either biotic stress or RWA-SA2 resistance responses. Future studies are required to biochemically confirm the involvement of these enzymes and proteins the specific metabolic pathways where they are found, in the wheat resistance mechanism against Russian wheat aphid Biotype 2
- Full Text:
- Date Issued: 2020
- Authors: Ntlokwana, Sitha Emmanuel
- Date: 2020
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18872 , vital:42888
- Description: Wheat (Triticum aestivum) is the second most-consumed cereal crop in the world, second only to maize. In South Africa it is mainly produced in three provinces; the Free State, Western Cape, and the Northen Cape. The average total land area used for wheat cultivation in these three Provinces, is 533 000 hectares, with a resultant annual production of between 1.3 to 2 million tons. The total wheat requirement in South Africa is currently 2.7 million tons according to the production of wheat guidelines published by the Department of Agriculture, Forestry and Fisheries, which is higher than the total annual production. One of the primary reasons that contribute to the lower production levels is insect and pest infestation, in particular, the Russian wheat aphid (Diurophis noxis), which can result in crop loss of up to sixty percent. Russian wheat aphids (RWA) are invasive insects that feed on the phloem of the plant through their specialised thin stylet-like mouthparts and release toxic agents contained in their saliva during feeding, which disrupt cellular functions inside the host plant. This damage leads to symptoms like; chlorosis, necrosis, wilting, stunting and curling of leaves, also known as leaf rolling. This study aimed to identify differentially expressed proteins in resistant and susceptible wheat (Triticum aestivum) cultivars during Russian wheat aphid Biotype South African 2 (RWA-SA2) infestation, in order to identify proteins involved in the wheat resistant mechanism against RWA-SA2. Two wheat cultivars SST398 (resistant to RWA-SA2) and SST356 (susceptible to RWA-SA2) were used, and a total number of 126 plants were planted and divided according to four different harvest times (Control day 0; day 5; day 7 and day 12). The wheat plants were infested with approximately 10 aphids per plant at the three-leaf stage, and placed within an insect cage inside a growth chamber (Conviron, Winnipeg, Canada) set at 24ºC, light intensity of 352 µmol.m-2.sec-1, ambient CO2 levels (410 ppm) and humidity of 60% with a 16h/8h day/night cycle. Wheat leaves were harvested at various time frames, and total protein extraction was performed. The protein samples were reduced with 10 mM dithiothreitol (DTT) and alkylated with 30 mM iodoacetamide (IAA). Sample clean-up and on-bead trypsin digest were performed on megReSyn Hilic columns, over four hours. The resultant peptides were vacuum dried and resuspended in 2% acetonitrile (ACN) before submitting them to LC-MS/MS (SWATH) for analysis. A total number of 611 proteins were differentially expressed, of which 19 were identified to be involved in the resistance response of wheat, and an additional 20 involved in biotic stress responses. This study showed that reactive oxidative species (ROS) such as hydrogen peroxide and hydroxyl radicals (OH-) play a significant role in the early stages of wheat resistance against RWA-SA2 infestation. They are involved in cell wall strengthening, activation of defence genes, involvement of phytohormone signals such as salicylic and jasmonic acid, which also mediates the systemic defences such as, systemic acquired resistance (SAR), leading to the expression of pathogen-related proteins such as (thaumatin-like proteins, oxalate oxidase, defensin, chitinase, and thionins). Although up-regulation of photosynthesis proteins such as (chlorophyll a/b binding protein, photosystem I and II, rubisco and divinyl chlorophyllide a, and 8 vinyl-reductase) were seen on both infested cultivars (susceptible and resistance), higher numbers of these classes of proteins were identified in the resistance cultivar, suggesting that they also play a critical role in resistance. In conclusion, the SWATH analysis used in this study was able to identify numerous proteins involved in the wheat resistance mechanism against RWA-SA2, most of which have not yet been reported to be involved in either biotic stress or RWA-SA2 resistance responses. Future studies are required to biochemically confirm the involvement of these enzymes and proteins the specific metabolic pathways where they are found, in the wheat resistance mechanism against Russian wheat aphid Biotype 2
- Full Text:
- Date Issued: 2020
Influence of Tamarix species on soil physicochemical properties and mapping its distribution and density using GIS in Western Cape, South Africa
- Authors: Mlahlwa, Asiphe
- Date: 2020
- Subjects: Tamarisks
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18588 , vital:42611
- Description: Tamarix ramosissima invasion is unarguably one of the worst ecological disasters in South Africa and is classified under category 1b by the National Environmental Management: Biodiversity Act 2014 (NEM: BA). The exotic Tamarix species was introduced in South Africa during the early 1900s as an ornamental or phytoremediating plant. This study was conducted to assess Tamarix distribution and evaluate its impact on soil physicochemical properties in two sites at Leeu River and Olifant River in Western Cape, South Africa. Samples were collected from Leeu River (which consists both the exotic and native Tamarix species) and Olifant River (only exotic Tamarix species). Three transects were laid from the water point outwards, with exotic Tamarix invading the river bank (first transect), the control on the open land (second transect) and the native Tamarix at the far end of the study site (third transect) in Leeu River. In Olifant, transects were laid according to the degree of invasion, low Tamarix density transect was referred to as T1, the medium as T2 and the high density as T3. Soil samples from each transect were taken from three points, at three soil depths (0-10, 10-20 and 20-30 cm) during winter and summer. Soil physiochemical properties such as soil pH, electro-conductivity (EC), total nitrogen (TN), total carbon (TC), soil organic carbon (SOC), sodium (Na+ ), potassium (K+ ), Calcium (Ca2+), Magnesium (Mg2+), bulk density, soil texture and sodium adsorption ratio (SAR) were determined. Soil chemicals properties including EC, Na+ , SAR, K+ and Mg2+ were found significantly higher under the native and the exotic Tamarix species when compared to Tamarix free soils. In general, salinity of surface soils (0–10 cm) was greater than those in the deeper soils with 5.05 mS/cm and 4.73 mS/cm observed under exotic and native Tamarix species, respectively. High levels of EC, K+ , Ca2+, Na+ , SAR, TN, TC and SOC were observed under T3, followed by T2 with the lowest being recorded in T1 at 0-10 cm. Unlike the soil EC, the effect of Tamarix density on soil pH at 0-10 cm soil profile was not significant. Alterations of soil physicochemical properties were more pronounced under the high Tamarix density as compared to the low invasion. Increased in distance from the river was related to a higher density of the invasive species and also topography had a major role in the change of species density. An increase in Tamarix density, results in high leaf litter which in turn results in salinity and soil nutrient at 0-10 cm. Soil salinity was dramatically increased under Tamarix species. Tamarix species are capable of altering the soil properties making it conducive for their growth.
- Full Text:
- Date Issued: 2020
- Authors: Mlahlwa, Asiphe
- Date: 2020
- Subjects: Tamarisks
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18588 , vital:42611
- Description: Tamarix ramosissima invasion is unarguably one of the worst ecological disasters in South Africa and is classified under category 1b by the National Environmental Management: Biodiversity Act 2014 (NEM: BA). The exotic Tamarix species was introduced in South Africa during the early 1900s as an ornamental or phytoremediating plant. This study was conducted to assess Tamarix distribution and evaluate its impact on soil physicochemical properties in two sites at Leeu River and Olifant River in Western Cape, South Africa. Samples were collected from Leeu River (which consists both the exotic and native Tamarix species) and Olifant River (only exotic Tamarix species). Three transects were laid from the water point outwards, with exotic Tamarix invading the river bank (first transect), the control on the open land (second transect) and the native Tamarix at the far end of the study site (third transect) in Leeu River. In Olifant, transects were laid according to the degree of invasion, low Tamarix density transect was referred to as T1, the medium as T2 and the high density as T3. Soil samples from each transect were taken from three points, at three soil depths (0-10, 10-20 and 20-30 cm) during winter and summer. Soil physiochemical properties such as soil pH, electro-conductivity (EC), total nitrogen (TN), total carbon (TC), soil organic carbon (SOC), sodium (Na+ ), potassium (K+ ), Calcium (Ca2+), Magnesium (Mg2+), bulk density, soil texture and sodium adsorption ratio (SAR) were determined. Soil chemicals properties including EC, Na+ , SAR, K+ and Mg2+ were found significantly higher under the native and the exotic Tamarix species when compared to Tamarix free soils. In general, salinity of surface soils (0–10 cm) was greater than those in the deeper soils with 5.05 mS/cm and 4.73 mS/cm observed under exotic and native Tamarix species, respectively. High levels of EC, K+ , Ca2+, Na+ , SAR, TN, TC and SOC were observed under T3, followed by T2 with the lowest being recorded in T1 at 0-10 cm. Unlike the soil EC, the effect of Tamarix density on soil pH at 0-10 cm soil profile was not significant. Alterations of soil physicochemical properties were more pronounced under the high Tamarix density as compared to the low invasion. Increased in distance from the river was related to a higher density of the invasive species and also topography had a major role in the change of species density. An increase in Tamarix density, results in high leaf litter which in turn results in salinity and soil nutrient at 0-10 cm. Soil salinity was dramatically increased under Tamarix species. Tamarix species are capable of altering the soil properties making it conducive for their growth.
- Full Text:
- Date Issued: 2020
Investigating carcass characteristics, meat quality and ageing effects on physicochemical attributes, lipid oxidation, and degradation of muscle proteins in mature beef and dairy cull cows
- Authors: Mpala, Bukhosi
- Date: 2020
- Subjects: Meat -- Quality Dairy cattle
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18777 , vital:42732
- Description: This study aimed to examine carcass characteristics, meat quality and postmortem ageing effects on physicochemical properties, lipid oxidation and muscle protein degradation in dairy and beef cull cows. Three cattle genotypes representing dairy {Holstein-Friesian (HF)}, beef {Bonsmara (BON)}, and a mixed purpose genotype {South Devon × Aberdeen Angus crossbreed (SD × AA)} were selected at a commercial abattoir lairage and used for this study. From each genotype, mature cows falling into the C-age class were then randomly chosen consisting of 24 HF, 31 BON and 26 SD × AA. The South African red meat classification system was used to evaluate carcass parameters, while objective measurements associated with meat quality {i.e., pH, colour (CIE L*, a*, b*), water holding capacity (WHC) and Warner-Bratzler shear force (WBSF)} were assessed in the M. longissimus thoracis et lumborum (LTL) muscle. Also, six cows were selected from each genotype within a carcass weight range of 290 ± 5 kg and fat score (FS) and conformation score (CS) of 2 and 3 respectively, and their meat was aged in a 4 ℃ chiller for 1, 7 or 14 days. At each ageing period, steaks were evaluated for pH, colour, WHC, WBSF and lipid oxidation. Furthermore, sub-samples were cut from each aged steak, vacuum-sealed, and stored in a freezer at -20 ℃ until needed for the determination of protein solubility and degradation of myofibrillar and sarcoplasmic proteins. Study results showed that the HF had a significantly (P < 0.05) lower dressing percentage than the BON and SD × AA. A total of 59% of the cull cows yielded lean carcasses, while 33% and 4% had a medium and fat subcutaneous fat score, respectively. The Holstein-Friesian recorded carcasses that had a fat score of 0 (2%) and a fat score of 1 (4%) while the Bonsmara had 20% C2, 16% C3 and 2% C4 carcasses, respectively. Most of the carcasses (78%) had a medium CS with the BON and SD × AA making up to 37% and 30%, respectively. All the measured meat quality attributes showed significant differences (P < 0.05) among the three cattle genotypes, except b*, hue angle and thawing loss. Notably, the HF recorded higher (P < 0.05) L*, a* and drip loss values but had a lower WBSF than the BON. The findings of the present study also showed that meat pH, colour traits, purge loss, lipid oxidation, cooking loss and WBSF were significantly (P < 0.05) influenced by post-mortem ageing and genotype. Except for SD × AA, WBSF only showed a significant decrease after 14 days of ageing. Moreover, significant (P < 0.05) ageing and genotype effects were observed on protein solubility and degradation of sarcoplasmic and myofibrillar proteins. One dimensional gel electrophoresis revealed the presence of several protein bands 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper with molecular weights ranges of 16 - 250 kDa and 12.5 – 166.6 kDa in the myofibrillar and sarcoplasmic protein extracts, respectively. The staining intensities of some the protein bands were significantly (P < 0.05) influenced by ageing and cattle genotype. In conclusion, the present study observed that carcass characteristics and meat quality traits vary among cattle genotypes with different production use. The data also revealed that physicochemical characteristics and degradation of muscle proteins is related to both cattle genotype and postmortem ageing. It is recommended that the meat of mature cull cows be aged under vacuum conditions for up to 14 days to improve its tenderness.
- Full Text:
- Date Issued: 2020
- Authors: Mpala, Bukhosi
- Date: 2020
- Subjects: Meat -- Quality Dairy cattle
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18777 , vital:42732
- Description: This study aimed to examine carcass characteristics, meat quality and postmortem ageing effects on physicochemical properties, lipid oxidation and muscle protein degradation in dairy and beef cull cows. Three cattle genotypes representing dairy {Holstein-Friesian (HF)}, beef {Bonsmara (BON)}, and a mixed purpose genotype {South Devon × Aberdeen Angus crossbreed (SD × AA)} were selected at a commercial abattoir lairage and used for this study. From each genotype, mature cows falling into the C-age class were then randomly chosen consisting of 24 HF, 31 BON and 26 SD × AA. The South African red meat classification system was used to evaluate carcass parameters, while objective measurements associated with meat quality {i.e., pH, colour (CIE L*, a*, b*), water holding capacity (WHC) and Warner-Bratzler shear force (WBSF)} were assessed in the M. longissimus thoracis et lumborum (LTL) muscle. Also, six cows were selected from each genotype within a carcass weight range of 290 ± 5 kg and fat score (FS) and conformation score (CS) of 2 and 3 respectively, and their meat was aged in a 4 ℃ chiller for 1, 7 or 14 days. At each ageing period, steaks were evaluated for pH, colour, WHC, WBSF and lipid oxidation. Furthermore, sub-samples were cut from each aged steak, vacuum-sealed, and stored in a freezer at -20 ℃ until needed for the determination of protein solubility and degradation of myofibrillar and sarcoplasmic proteins. Study results showed that the HF had a significantly (P < 0.05) lower dressing percentage than the BON and SD × AA. A total of 59% of the cull cows yielded lean carcasses, while 33% and 4% had a medium and fat subcutaneous fat score, respectively. The Holstein-Friesian recorded carcasses that had a fat score of 0 (2%) and a fat score of 1 (4%) while the Bonsmara had 20% C2, 16% C3 and 2% C4 carcasses, respectively. Most of the carcasses (78%) had a medium CS with the BON and SD × AA making up to 37% and 30%, respectively. All the measured meat quality attributes showed significant differences (P < 0.05) among the three cattle genotypes, except b*, hue angle and thawing loss. Notably, the HF recorded higher (P < 0.05) L*, a* and drip loss values but had a lower WBSF than the BON. The findings of the present study also showed that meat pH, colour traits, purge loss, lipid oxidation, cooking loss and WBSF were significantly (P < 0.05) influenced by post-mortem ageing and genotype. Except for SD × AA, WBSF only showed a significant decrease after 14 days of ageing. Moreover, significant (P < 0.05) ageing and genotype effects were observed on protein solubility and degradation of sarcoplasmic and myofibrillar proteins. One dimensional gel electrophoresis revealed the presence of several protein bands 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper with molecular weights ranges of 16 - 250 kDa and 12.5 – 166.6 kDa in the myofibrillar and sarcoplasmic protein extracts, respectively. The staining intensities of some the protein bands were significantly (P < 0.05) influenced by ageing and cattle genotype. In conclusion, the present study observed that carcass characteristics and meat quality traits vary among cattle genotypes with different production use. The data also revealed that physicochemical characteristics and degradation of muscle proteins is related to both cattle genotype and postmortem ageing. It is recommended that the meat of mature cull cows be aged under vacuum conditions for up to 14 days to improve its tenderness.
- Full Text:
- Date Issued: 2020
Joint Modelling Inference for Longitudinal and Time To Event Data with Application to Biomarkers in Medical and Clinical Studies
- Authors: Azeez, Adeboye Nurudeen
- Date: 2020
- Subjects: Biochemical markers Bayesian statistical decision theory
- Language: English
- Type: Thesis , Doctoral , PhD (Biostatistics)
- Identifier: http://hdl.handle.net/10353/18476 , vital:42543
- Description: In the past couple of decades, longitudinal and survival data analysis have emerged as important and popular concepts of biostatistics and statistics for disease modelling. In recent years, these two statistics concepts have been combined to develop a joint model for longitudinal and survival data analysis. The Joint model is a simultaneous modelling application of longitudinal and survival data while taking into account a possible association between them. In this thesis, three sub-topics (Conditional score approach, estimating equation approach, and modified Cholesky decomposition approach) are utilised to model the association if the independence assumption is violated. Using the conditional score approach, the study investigated the association between longitudinal covariates and the time-to-event process to examine the within-subject measurement error that could influence estimation when the assumption of normality and mutual independence is violated. Given the assumption violation, I proposed an estimating equation approach based on the conditional score to relax parametric distributional assumptions for repeated measures of random effects. I jointly modelled the time-dependent biomarkers and event times using the Cox model with intermittent time-dependent covariates measure, in which the longitudinal model was used to characterize the biomarker underlying (unobservable) trajectory and incorporated as a latent time-dependent covariate in the survival model to predict failure times. Estimates of the parameters were obtained by a restricted maximum likelihood estimate (REML). A modified Cholesky decomposition method was used to capture the within-subject covariance for a positive definite and symmetric matrix, with the assumption that the observed data from different subjects are independent. I illustrated the proposed method by a real data set from a lung study and simulation. An extension to the joint model of longitudinal-survival data was also proposed, in which the longitudinal data has a cumulative and weighted effect on the hazard event function. Using a Bayesian parametric method, I proposed a skewed weighted probability density function to estimate the parameters. The weighted cumulative effect used enabled different longitudinal profiles to be incorporated over time in calculating the hazard ratio between the subjects. The proposed functions provide greater flexibility for modelling the association structure of different longitudinal and survival sub-model. The focus was on the association between the biomarker (serum creatinine, sCr) and the development of end-stage renal disease (ESRD). Since the effect of sCr biomarker is anticipated to be a cumulative effect, with the development of sCr biomarker over time leading to progressively higher damage of the kidney. The approach was applied a simulation for validation of the proposed method
- Full Text:
- Date Issued: 2020
- Authors: Azeez, Adeboye Nurudeen
- Date: 2020
- Subjects: Biochemical markers Bayesian statistical decision theory
- Language: English
- Type: Thesis , Doctoral , PhD (Biostatistics)
- Identifier: http://hdl.handle.net/10353/18476 , vital:42543
- Description: In the past couple of decades, longitudinal and survival data analysis have emerged as important and popular concepts of biostatistics and statistics for disease modelling. In recent years, these two statistics concepts have been combined to develop a joint model for longitudinal and survival data analysis. The Joint model is a simultaneous modelling application of longitudinal and survival data while taking into account a possible association between them. In this thesis, three sub-topics (Conditional score approach, estimating equation approach, and modified Cholesky decomposition approach) are utilised to model the association if the independence assumption is violated. Using the conditional score approach, the study investigated the association between longitudinal covariates and the time-to-event process to examine the within-subject measurement error that could influence estimation when the assumption of normality and mutual independence is violated. Given the assumption violation, I proposed an estimating equation approach based on the conditional score to relax parametric distributional assumptions for repeated measures of random effects. I jointly modelled the time-dependent biomarkers and event times using the Cox model with intermittent time-dependent covariates measure, in which the longitudinal model was used to characterize the biomarker underlying (unobservable) trajectory and incorporated as a latent time-dependent covariate in the survival model to predict failure times. Estimates of the parameters were obtained by a restricted maximum likelihood estimate (REML). A modified Cholesky decomposition method was used to capture the within-subject covariance for a positive definite and symmetric matrix, with the assumption that the observed data from different subjects are independent. I illustrated the proposed method by a real data set from a lung study and simulation. An extension to the joint model of longitudinal-survival data was also proposed, in which the longitudinal data has a cumulative and weighted effect on the hazard event function. Using a Bayesian parametric method, I proposed a skewed weighted probability density function to estimate the parameters. The weighted cumulative effect used enabled different longitudinal profiles to be incorporated over time in calculating the hazard ratio between the subjects. The proposed functions provide greater flexibility for modelling the association structure of different longitudinal and survival sub-model. The focus was on the association between the biomarker (serum creatinine, sCr) and the development of end-stage renal disease (ESRD). Since the effect of sCr biomarker is anticipated to be a cumulative effect, with the development of sCr biomarker over time leading to progressively higher damage of the kidney. The approach was applied a simulation for validation of the proposed method
- Full Text:
- Date Issued: 2020
Laypersons’ perceptions and livelihood uses of invasive alien species (Opuntia ficus-indica) in the Eastern Cape Province, South Africa
- Authors: Mdweshu, Luleka
- Date: 2020
- Subjects: Opuntia ficus-indica
- Language: English
- Type: Thesis , Masters , MSc (Botany)
- Identifier: http://hdl.handle.net/10353/18720 , vital:42727
- Description: Opuntia ficus-indica is a succulent plant species that originated from Mexico and parts of neighbouring middle-America and introduced in South Africa by white settlers in the eighteenth century. The species is now categorized as invasive in South Africa but has both commercial and non-market uses. This study evaluated the livelihood uses and local perceptions of O. ficus-indica of rural residents in Makana, Ngqushwa and Raymond Mhlaba Local Municipalities in the Eastern Cape province in South Africa. Data on the livelihood uses and local perceptions on the species in the study area were gathered through community focus group discussions and household surveys using semi-structured questionnaires between June 2018 and August 2019. A sample of 150 participants selected via snowball-sampling technique provided detailed accounts on utilization of O. ficus-indica in the study area. The importance of O. ficus-indica as a useful plant species was ubiquitously perceived, with all respondents reporting its contribution towards their livelihood needs and more than three quarters (88.0%) using the species on a regular basis. Majority of the respondents (41.0%) regarded O. ficus-indica as an important source of cash income while about a third (33.0%) regarded the species as an important source of food products and nutrition. Interviews with respondents revealed that O. ficusindica is currently being harvested from the wild with 73.3% of the respondents reporting that the abundance of the species was decreasing. The positive socioeconomic contributions of O. ficus-indica need to be taken into account when assessing the costs resulting from invasions caused by alien plant species. This study is a crucial starting point in trying to understand and initiate the management of alien invasive species such as O. ficus-indica. Results of this study are also important for understanding local peoples’ perceptions of new introductions and management of existing alien plants in the province.
- Full Text:
- Date Issued: 2020
- Authors: Mdweshu, Luleka
- Date: 2020
- Subjects: Opuntia ficus-indica
- Language: English
- Type: Thesis , Masters , MSc (Botany)
- Identifier: http://hdl.handle.net/10353/18720 , vital:42727
- Description: Opuntia ficus-indica is a succulent plant species that originated from Mexico and parts of neighbouring middle-America and introduced in South Africa by white settlers in the eighteenth century. The species is now categorized as invasive in South Africa but has both commercial and non-market uses. This study evaluated the livelihood uses and local perceptions of O. ficus-indica of rural residents in Makana, Ngqushwa and Raymond Mhlaba Local Municipalities in the Eastern Cape province in South Africa. Data on the livelihood uses and local perceptions on the species in the study area were gathered through community focus group discussions and household surveys using semi-structured questionnaires between June 2018 and August 2019. A sample of 150 participants selected via snowball-sampling technique provided detailed accounts on utilization of O. ficus-indica in the study area. The importance of O. ficus-indica as a useful plant species was ubiquitously perceived, with all respondents reporting its contribution towards their livelihood needs and more than three quarters (88.0%) using the species on a regular basis. Majority of the respondents (41.0%) regarded O. ficus-indica as an important source of cash income while about a third (33.0%) regarded the species as an important source of food products and nutrition. Interviews with respondents revealed that O. ficusindica is currently being harvested from the wild with 73.3% of the respondents reporting that the abundance of the species was decreasing. The positive socioeconomic contributions of O. ficus-indica need to be taken into account when assessing the costs resulting from invasions caused by alien plant species. This study is a crucial starting point in trying to understand and initiate the management of alien invasive species such as O. ficus-indica. Results of this study are also important for understanding local peoples’ perceptions of new introductions and management of existing alien plants in the province.
- Full Text:
- Date Issued: 2020
Mineralogy, geochemistry and pebble morphology of the Katberg Formation around Graaff Reinet and East London, Eastern Cape province of South Africa
- Authors: Ndlazi, Nondumiso Zandile
- Date: 2020
- Subjects: Mineralogy|
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: http://hdl.handle.net/10353/18631 , vital:42615
- Description: The Katberg Formation forms the upper part of the Tarkastad Subgroup in the Beaufort Group of the main Karoo Supergroup. The Katberg Formation consists of siliciclastic sedimentary rocks mostly dominated by greyish sandstone, red mudstone with minor siltstone occurrences. The Katberg Formation also consists of calcareous and ferruginous concretions that formed during diagenesis. Braided streams deposited the Katberg Formation with a predominantly sand bed load. The Katberg Formation sandstones contain pebbles with no true conglomerates identified in the study area. This study was conducted in the Katberg Formation to understand the mineralogy, geochemistry, and pebble morphology around Graaff Reinet and East London areas. The major and trace elements were analyzed through X-Ray Fluorescence (XRF) to deduce the source rock provenance, tectonic setting, paleo-weathering conditions, climatic conditions, and sediment maturity. The X-Ray Diffraction (XRD) was used to highlight a detailed distribution and variation of mineralogical polymorphs of the minerals present in sandstones and mudstones. The pebble morphology was used to confirm the depositional environment of the Katberg Formation. The use of The bivariate plots of the Maximum Projection Sphericity Index (MPSI) and the Oblate-Prolate Index (OPI) showed that 79 % of pebbles fall in the fluvial environment, whereas 21 % of pebbles fall in the beach environment. A small proportion of beach pebbles within the Katberg Formation suggests that the river reached the marginal marine environment during its flow. The majority of the pebbles yielded a bladed shape with a dominating Sphericity Index symptomatic of fluvial sediments. All the bivariate plots illustrate the fluvial depositional environment for the sediments of the Katberg Formation. Petrographic studies based on the prepared 15 thin sections indicated that the Katberg Formation rocks are dominated by quartz, feldspar, and clay minerals. However, they show more plagioclase feldspar than k-feldspars. The grains are poorly sorted and immature, with irregular grain sizes and shapes. The angularity of clasts indicates that the grains have travelled shorter distances. The abundance of feldspar minerals suggests that the arkose sandstone was derived either from situ or from a short distance. The albitization of plagioclase to illite and the replacement of plagioclase feldspars by calcite and laumontite is very common in the Katberg Formation, which points out deep burial diagenesis. The XRD analysis revealed the occurrence of 14 minerals in the siliciclastic rocks of the Katberg Formation, namely: quartz, albite, clinochlore, muscovite, phlogopite, annite, illite, orthoclase, anorthoclase, laumontite, calcite, and ankerite. Amongst these minerals, albite, clinochlore, muscovite, and phlogopite show variation in crystal forms known as polymorphs. Geochemical analysis of the Katberg Formation sandstones and mudrocks revealed that all samples show a high concentration of SiO2, Al2O3, Fe2O3, K2O, Na2O, CaO, and MgO. The trace elements: TiO2, MnO, P2O5, BaO, SrO, ZrO2, and V2O5 are depleted with values ranging below 1 wt %. The geochemical classification of the Katberg Formation sandstones revealed the origin from wacke and arkose sources. The geochemical diagrams and indices of paleoweathering conditions suggested that the Katberg Formation underwent a moderate degree of chemical weathering. The geochemistry revealed that the sediments were 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper deposited during the arid climate conditions. The studied sandstone and mudstone samples pointed an active continental margin and passive margin tectonic setting of the Katberg Formation.
- Full Text:
- Date Issued: 2020
- Authors: Ndlazi, Nondumiso Zandile
- Date: 2020
- Subjects: Mineralogy|
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: http://hdl.handle.net/10353/18631 , vital:42615
- Description: The Katberg Formation forms the upper part of the Tarkastad Subgroup in the Beaufort Group of the main Karoo Supergroup. The Katberg Formation consists of siliciclastic sedimentary rocks mostly dominated by greyish sandstone, red mudstone with minor siltstone occurrences. The Katberg Formation also consists of calcareous and ferruginous concretions that formed during diagenesis. Braided streams deposited the Katberg Formation with a predominantly sand bed load. The Katberg Formation sandstones contain pebbles with no true conglomerates identified in the study area. This study was conducted in the Katberg Formation to understand the mineralogy, geochemistry, and pebble morphology around Graaff Reinet and East London areas. The major and trace elements were analyzed through X-Ray Fluorescence (XRF) to deduce the source rock provenance, tectonic setting, paleo-weathering conditions, climatic conditions, and sediment maturity. The X-Ray Diffraction (XRD) was used to highlight a detailed distribution and variation of mineralogical polymorphs of the minerals present in sandstones and mudstones. The pebble morphology was used to confirm the depositional environment of the Katberg Formation. The use of The bivariate plots of the Maximum Projection Sphericity Index (MPSI) and the Oblate-Prolate Index (OPI) showed that 79 % of pebbles fall in the fluvial environment, whereas 21 % of pebbles fall in the beach environment. A small proportion of beach pebbles within the Katberg Formation suggests that the river reached the marginal marine environment during its flow. The majority of the pebbles yielded a bladed shape with a dominating Sphericity Index symptomatic of fluvial sediments. All the bivariate plots illustrate the fluvial depositional environment for the sediments of the Katberg Formation. Petrographic studies based on the prepared 15 thin sections indicated that the Katberg Formation rocks are dominated by quartz, feldspar, and clay minerals. However, they show more plagioclase feldspar than k-feldspars. The grains are poorly sorted and immature, with irregular grain sizes and shapes. The angularity of clasts indicates that the grains have travelled shorter distances. The abundance of feldspar minerals suggests that the arkose sandstone was derived either from situ or from a short distance. The albitization of plagioclase to illite and the replacement of plagioclase feldspars by calcite and laumontite is very common in the Katberg Formation, which points out deep burial diagenesis. The XRD analysis revealed the occurrence of 14 minerals in the siliciclastic rocks of the Katberg Formation, namely: quartz, albite, clinochlore, muscovite, phlogopite, annite, illite, orthoclase, anorthoclase, laumontite, calcite, and ankerite. Amongst these minerals, albite, clinochlore, muscovite, and phlogopite show variation in crystal forms known as polymorphs. Geochemical analysis of the Katberg Formation sandstones and mudrocks revealed that all samples show a high concentration of SiO2, Al2O3, Fe2O3, K2O, Na2O, CaO, and MgO. The trace elements: TiO2, MnO, P2O5, BaO, SrO, ZrO2, and V2O5 are depleted with values ranging below 1 wt %. The geochemical classification of the Katberg Formation sandstones revealed the origin from wacke and arkose sources. The geochemical diagrams and indices of paleoweathering conditions suggested that the Katberg Formation underwent a moderate degree of chemical weathering. The geochemistry revealed that the sediments were 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper deposited during the arid climate conditions. The studied sandstone and mudstone samples pointed an active continental margin and passive margin tectonic setting of the Katberg Formation.
- Full Text:
- Date Issued: 2020
Preparation and characterization of sodium alginate-based dissolvable bandages as potential wound dressings
- Authors: Ndlovu, Sindi Prescila
- Date: 2020
- Subjects: Nanostructured materials
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: http://hdl.handle.net/10353/18800 , vital:42734
- Description: Burn wounds are among the leading causes of mortality and morbidity globally. Burn wounds are painful, cause social isolation and causes post-traumatic stress disorder (PTSD) due to prolonged hospital treatment. The challenges encountered in the treatment of burn wounds are infections resulting from the use of wound dressings that do not protect the wounds from microbial invasion. Sodium alginate-based dissolvable bandages were prepared and encapsulated with various antibiotics (ampicillin and ciprofloxacin) and nanoparticles (i.e. zinc oxide and silver). The dissolvable bandages were characterized by FTIR, SEM/EDX, TEM, XRD and TGA. Furthermore, the porosity, water uptake, biodegradation, antibacterial studies, and water vapour transmittance properties of the bandages were also studied. The prepared sodium alginate-based dissolvable bandage incorporated with varied amount of drugs (such as ampicillin, ciprofloxacin, zinc oxide and silver nanoparticle) exhibited good porosity, high water uptake, excellent WVTR with sustained drug release profiles. The loading of ZnO Nps, CLP/ZnO Nps and Ag Nps/CLP into the bandages improved the antibacterial activity of the bandages against both gram-negative and gram-positive strains of bacteria. XRD confirmed the amorphous nature of the dissolvable bandage and the absence of free drugs. FTIR revealed the successful encapsulation of the antibiotics and nanoparticle into the dissolvable bandages. The dissolvable bandages exhibited high water uptake ranging from 870-4468% with good porosity suggesting that they can absorb large amount of wound exudates. The drug release for all the bandages obeyed the Korsemeyer Peppas drug release model with n values in the range 0.1-1.0. The results obtained indicate that the bandages are potential wound dressings for burns and for patients with sensitive skins.
- Full Text:
- Date Issued: 2020
- Authors: Ndlovu, Sindi Prescila
- Date: 2020
- Subjects: Nanostructured materials
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: http://hdl.handle.net/10353/18800 , vital:42734
- Description: Burn wounds are among the leading causes of mortality and morbidity globally. Burn wounds are painful, cause social isolation and causes post-traumatic stress disorder (PTSD) due to prolonged hospital treatment. The challenges encountered in the treatment of burn wounds are infections resulting from the use of wound dressings that do not protect the wounds from microbial invasion. Sodium alginate-based dissolvable bandages were prepared and encapsulated with various antibiotics (ampicillin and ciprofloxacin) and nanoparticles (i.e. zinc oxide and silver). The dissolvable bandages were characterized by FTIR, SEM/EDX, TEM, XRD and TGA. Furthermore, the porosity, water uptake, biodegradation, antibacterial studies, and water vapour transmittance properties of the bandages were also studied. The prepared sodium alginate-based dissolvable bandage incorporated with varied amount of drugs (such as ampicillin, ciprofloxacin, zinc oxide and silver nanoparticle) exhibited good porosity, high water uptake, excellent WVTR with sustained drug release profiles. The loading of ZnO Nps, CLP/ZnO Nps and Ag Nps/CLP into the bandages improved the antibacterial activity of the bandages against both gram-negative and gram-positive strains of bacteria. XRD confirmed the amorphous nature of the dissolvable bandage and the absence of free drugs. FTIR revealed the successful encapsulation of the antibiotics and nanoparticle into the dissolvable bandages. The dissolvable bandages exhibited high water uptake ranging from 870-4468% with good porosity suggesting that they can absorb large amount of wound exudates. The drug release for all the bandages obeyed the Korsemeyer Peppas drug release model with n values in the range 0.1-1.0. The results obtained indicate that the bandages are potential wound dressings for burns and for patients with sensitive skins.
- Full Text:
- Date Issued: 2020
Resource Allocation Framework in Fog Computing for the Internet of Things Environments
- Authors: Vambe, William Tichaona
- Date: 2020
- Subjects: Internet of things Cloud computing
- Language: English
- Type: Thesis , Doctoral , PhD (Computer Science)
- Identifier: http://hdl.handle.net/10353/18498 , vital:42575
- Description: Fog computing plays a pivotal role in the Internet of Things (IoT) ecosystem because of its ability to support delay-sensitive tasks, bringing resources from cloud servers closer to the “ground” and support IoT devices that are resource-constrained. Although fog computing offers some benefits such as quick response to requests, geo-distributed data processing and data processing in the proximity of the IoT devices, the exponential increase of IoT devices and large volumes of data being generated has led to a new set of challenges. One such problem is the allocation of resources to IoT tasks to match their computational needs and quality of service (QoS) requirements, whilst meeting both task deadlines and user expectations. Most proposed solutions in existing works suggest task offloading mechanisms where IoT devices would offload their tasks randomly to the fog layer or cloud layer. This helps in minimizing the communication delay; however, most tasks would end up missing their deadlines as many delays are experienced during offloading. This study proposes and introduces a Resource Allocation Scheduler (RAS) at the IoT-Fog gateway, whose goal is to decide where and when a task is to be offloaded, either to the fog layer, or the cloud layer based on their priority needs, computational needs and QoS requirements. The aim directly places work within the communication networks domain, in the transport layer of the Open Systems Interconnection (OSI) model. As such, this study follows the four phases of the top-down approach because of its reusability characteristics. To validate and test the efficiency and effectiveness of the RAS, the fog framework was implemented and evaluated in a simulated smart home setup. The essential metrics that were used to check if round-trip time was minimized are the queuing time, offloading time and throughput for QoS. The results showed that the RAS helps to reduce the round-trip time, increases throughput and leads to improved QoS. Furthermore, the approach addressed the starvation problem, a phenomenon that tends to affect low priority tasks. Most importantly, the results provides evidence that if resource allocation and assignment are appropriately done, round-trip time can be reduced and QoS can be improved in fog computing. The significant contribution of this research is the novel framework which minimizes round-trip time, addresses the starvation problem and improves QoS. Moreover, a literature reviewed paper which was regarded by reviewers as the first, as far as QoS in fog computing is concerned was produced.
- Full Text:
- Date Issued: 2020
- Authors: Vambe, William Tichaona
- Date: 2020
- Subjects: Internet of things Cloud computing
- Language: English
- Type: Thesis , Doctoral , PhD (Computer Science)
- Identifier: http://hdl.handle.net/10353/18498 , vital:42575
- Description: Fog computing plays a pivotal role in the Internet of Things (IoT) ecosystem because of its ability to support delay-sensitive tasks, bringing resources from cloud servers closer to the “ground” and support IoT devices that are resource-constrained. Although fog computing offers some benefits such as quick response to requests, geo-distributed data processing and data processing in the proximity of the IoT devices, the exponential increase of IoT devices and large volumes of data being generated has led to a new set of challenges. One such problem is the allocation of resources to IoT tasks to match their computational needs and quality of service (QoS) requirements, whilst meeting both task deadlines and user expectations. Most proposed solutions in existing works suggest task offloading mechanisms where IoT devices would offload their tasks randomly to the fog layer or cloud layer. This helps in minimizing the communication delay; however, most tasks would end up missing their deadlines as many delays are experienced during offloading. This study proposes and introduces a Resource Allocation Scheduler (RAS) at the IoT-Fog gateway, whose goal is to decide where and when a task is to be offloaded, either to the fog layer, or the cloud layer based on their priority needs, computational needs and QoS requirements. The aim directly places work within the communication networks domain, in the transport layer of the Open Systems Interconnection (OSI) model. As such, this study follows the four phases of the top-down approach because of its reusability characteristics. To validate and test the efficiency and effectiveness of the RAS, the fog framework was implemented and evaluated in a simulated smart home setup. The essential metrics that were used to check if round-trip time was minimized are the queuing time, offloading time and throughput for QoS. The results showed that the RAS helps to reduce the round-trip time, increases throughput and leads to improved QoS. Furthermore, the approach addressed the starvation problem, a phenomenon that tends to affect low priority tasks. Most importantly, the results provides evidence that if resource allocation and assignment are appropriately done, round-trip time can be reduced and QoS can be improved in fog computing. The significant contribution of this research is the novel framework which minimizes round-trip time, addresses the starvation problem and improves QoS. Moreover, a literature reviewed paper which was regarded by reviewers as the first, as far as QoS in fog computing is concerned was produced.
- Full Text:
- Date Issued: 2020
Smallholder farmers’ adaptation strategies to mitigate the effect of drought on maize production in O.R Tambo District Municipality
- Authors: Masinda, Nasiphi
- Date: 2020
- Subjects: Farms, Small
- Language: English
- Type: Thesis , Masters , MSc (Agricultural Economics)
- Identifier: http://hdl.handle.net/10353/18709 , vital:42726
- Description: Drought is a normal periodical event that influences the livelihoods of millions of people around the world and it is considered one of the most devastating natural disasters in economic, social and environmental terms. South Africa is considered a semi-arid country vulnerable to water stress, particularly drought. Drought is expected to affect maize production in South Africa in the coming years. Although drought cannot be controlled, producers can adopt adaptation practices to reduce yield loss caused by drought. Maize is a staple crop in South Africa, which makes it the most important grain crop, being both the major feed grain and the staple food of the majority of the South African population. Literature has identified and presented several adaptation strategies that farmers can use however, it has not been conclusively investigated whether vulnerable smallholder farmers affected by drought are able to use or benefit from them. The study examined drought adaptation strategies employed by smallholder farmers and factors affecting adoption and intensity of adoption of drought mitigation strategies. This study determined smallholder farmer’s adoption of adaptation strategies to mitigate the effects of drought on maize production in O.R Tambo district municipality. The study was carried in ORTDM in the Eastern Cape Province of South Africa. A mixed methods approach utilizing qualitative and quantitative data was employed. Both primary and secondary data sources were used for this study. The study gathered data from ORTDM in the Eastern Cape from 200 smallholder maize producers. Primary data was collected through a structured questionnaire and was complemented by secondary data on maize production, yield and area planted sourced from the Department of Agriculture Forestry and Fisheries. The data collected were analysed using descriptive statistics, the adaptation strategy index in the Statistical Package for Social Sciences (SPSS) software and double hurdle model used Statistical package called STATA (version 12. Results from descriptive analysis identified separate livelihood adoptions which were, increase fertilizer, use savings, indigenous knowledge, sell livestock, off-farm income (salary) and reduction of production. The adaptation strategies adopted by maize farmers are mostly shifting planting date, reduction of maize cultivated area and intercropping. The double hurdle model was used to estimate the factors affecting the farmers’ adoption of drought mitigation strategies and factors which were found to be statistically significant were gender of the household head, level of education of the household head, household size, extension services and land ownership. The Adaptation Strategy Index was used in order to establish the relationship between adopting adaptation strategies and maize production. The farmers ranked the adaptation strategies in terms of their useful in adapting with drought and successfully alleviating decline in maize production. Shifting of planting date, reduction of maize cultivated area, planting drought resistant varieties, crop diversification and intercropping were ranked as the most useful respectively. The findings of this study have a number of policy implications since a number of farmers did nothing to adapt to the effects of drought hence supporting smallholder farmers through training on climate change adaption and adapting options is necessary. Training targeting female headed and poor farmers can have significant positive impacts for increasing the implementation of drought adaptation strategies.
- Full Text:
- Date Issued: 2020
- Authors: Masinda, Nasiphi
- Date: 2020
- Subjects: Farms, Small
- Language: English
- Type: Thesis , Masters , MSc (Agricultural Economics)
- Identifier: http://hdl.handle.net/10353/18709 , vital:42726
- Description: Drought is a normal periodical event that influences the livelihoods of millions of people around the world and it is considered one of the most devastating natural disasters in economic, social and environmental terms. South Africa is considered a semi-arid country vulnerable to water stress, particularly drought. Drought is expected to affect maize production in South Africa in the coming years. Although drought cannot be controlled, producers can adopt adaptation practices to reduce yield loss caused by drought. Maize is a staple crop in South Africa, which makes it the most important grain crop, being both the major feed grain and the staple food of the majority of the South African population. Literature has identified and presented several adaptation strategies that farmers can use however, it has not been conclusively investigated whether vulnerable smallholder farmers affected by drought are able to use or benefit from them. The study examined drought adaptation strategies employed by smallholder farmers and factors affecting adoption and intensity of adoption of drought mitigation strategies. This study determined smallholder farmer’s adoption of adaptation strategies to mitigate the effects of drought on maize production in O.R Tambo district municipality. The study was carried in ORTDM in the Eastern Cape Province of South Africa. A mixed methods approach utilizing qualitative and quantitative data was employed. Both primary and secondary data sources were used for this study. The study gathered data from ORTDM in the Eastern Cape from 200 smallholder maize producers. Primary data was collected through a structured questionnaire and was complemented by secondary data on maize production, yield and area planted sourced from the Department of Agriculture Forestry and Fisheries. The data collected were analysed using descriptive statistics, the adaptation strategy index in the Statistical Package for Social Sciences (SPSS) software and double hurdle model used Statistical package called STATA (version 12. Results from descriptive analysis identified separate livelihood adoptions which were, increase fertilizer, use savings, indigenous knowledge, sell livestock, off-farm income (salary) and reduction of production. The adaptation strategies adopted by maize farmers are mostly shifting planting date, reduction of maize cultivated area and intercropping. The double hurdle model was used to estimate the factors affecting the farmers’ adoption of drought mitigation strategies and factors which were found to be statistically significant were gender of the household head, level of education of the household head, household size, extension services and land ownership. The Adaptation Strategy Index was used in order to establish the relationship between adopting adaptation strategies and maize production. The farmers ranked the adaptation strategies in terms of their useful in adapting with drought and successfully alleviating decline in maize production. Shifting of planting date, reduction of maize cultivated area, planting drought resistant varieties, crop diversification and intercropping were ranked as the most useful respectively. The findings of this study have a number of policy implications since a number of farmers did nothing to adapt to the effects of drought hence supporting smallholder farmers through training on climate change adaption and adapting options is necessary. Training targeting female headed and poor farmers can have significant positive impacts for increasing the implementation of drought adaptation strategies.
- Full Text:
- Date Issued: 2020
Socio-economic Impacts of Solar Energy in Rural Communities’ Livelihoods and the Scale/type of Technology Intervention: Case of Ingquza Hill Local Municipality, Eastern Cape Province, South Africa
- Authors: Bongoza, Sibulele
- Date: 2020
- Subjects: Solar energy Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc (Geography)
- Identifier: http://hdl.handle.net/10353/18610 , vital:42613
- Description: Energy from renewable sources has attracted significant global interest in recent years due to climate change, pollution, extreme environmental impacts and a marked increase in fuel costs for conventional generation methods, which is coal. This has led to major investment in renewable energy sources. Through the lens of sustainable livelihoods framework, the study aims at establishing the socioeconomic impacts brought by the provision of solar energy systems on rural livelihoods at Ingquza Hill Local Municipality in the Eastern Cape Province of South Africa. The study adopts an intensive research design in line with the qualitative approach. Data were collected using questionnaires from the households at Mkhamela village and in-depth interviews with the local councillor and the Chief of Mkhamela village at Ingquza Hill Local Municipality. The use of solar energy systems has been found to improve the rural people’s livelihoods. The rural people’s livelihoods have been transformed in terms of creation of employment opportunities, improved levels of education through powering schools and households as well as improved health conditions.
- Full Text:
- Date Issued: 2020
- Authors: Bongoza, Sibulele
- Date: 2020
- Subjects: Solar energy Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc (Geography)
- Identifier: http://hdl.handle.net/10353/18610 , vital:42613
- Description: Energy from renewable sources has attracted significant global interest in recent years due to climate change, pollution, extreme environmental impacts and a marked increase in fuel costs for conventional generation methods, which is coal. This has led to major investment in renewable energy sources. Through the lens of sustainable livelihoods framework, the study aims at establishing the socioeconomic impacts brought by the provision of solar energy systems on rural livelihoods at Ingquza Hill Local Municipality in the Eastern Cape Province of South Africa. The study adopts an intensive research design in line with the qualitative approach. Data were collected using questionnaires from the households at Mkhamela village and in-depth interviews with the local councillor and the Chief of Mkhamela village at Ingquza Hill Local Municipality. The use of solar energy systems has been found to improve the rural people’s livelihoods. The rural people’s livelihoods have been transformed in terms of creation of employment opportunities, improved levels of education through powering schools and households as well as improved health conditions.
- Full Text:
- Date Issued: 2020
Spatio-temporal variation of the land surface parameters in Temperature, in King Williams Town, Eastern Cape Province, South Africa
- Authors: Willie, Yanga Adrian
- Date: 2020
- Subjects: Environmental sciences
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12106 , vital:39152
- Description: The world is currently experiencing unprecedented urban growth. The influx of people into urban areas from rural areas is motivated by both economic and social factors such as increased employment opportunities. The latter is a result of, in part, industrialization, and the perceived higher standard of living that is often associated with access to better infrastructure. Surface Heat Island (SHI) is a phenomenon whereby urban areas experience higher surface temperatures than the surrounding rural areas. The presence of the SHI in urban areas has a negative impact not only on city dwellers, but also on the environment and the economy. The development of SHI is often associated with patterns of land use and land cover in urban areas. Numerous methods exist that can be used to study SHI’s. Literature suggests that Land Surface Temperature (LST), derived from satellite imagery, is a proven method that produces reliable results. The aim of this study was to evaluate the SHI in King Williams Town by studying the relationship between land surface temperatures, land cover and land cover indices. The derived indices are the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built up Index (NDBI). These indices were selected because they are representative of the land cover scheme used in the research study. This study was conducted in the King Williams town area between the years 1995 and 2018 the land surface temperature was derived from Landsat ETM + high thermal band data. The findings from this study provide an idea on the correlation between satellite derived land surface temperature and the land modification which occurred during the urbanization of King Williams Town during a 23 year period between1995 and 2018. The built up land category was the most influential in the development of high land surface temperature levels , vegetation had an opposite effect as a series of data sets illustrated that vegetated areas had a iv cooling effect on the surface. Water bodies in the study area had an insignificant effect on the Surface temperature levels while the grass lands weren’t as cooling as the vegetation but provided a cooling environment in the study area .The spatial distribution of areas of high surface temperature (hot spots) was discovered to be concentrated in the urban areas of the study area which is in the northwest region of the study area and correlates to the land cover and land cover indices associated with built up and artificial surfaces. The cooler areas or patches of land with lower values of land surface temperature were distributed on the outskirts of the study area away from the CBD and residential areas. This was the case because of the high concentration of vegetation and thicker grass lands in those regions.
- Full Text:
- Date Issued: 2020
- Authors: Willie, Yanga Adrian
- Date: 2020
- Subjects: Environmental sciences
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12106 , vital:39152
- Description: The world is currently experiencing unprecedented urban growth. The influx of people into urban areas from rural areas is motivated by both economic and social factors such as increased employment opportunities. The latter is a result of, in part, industrialization, and the perceived higher standard of living that is often associated with access to better infrastructure. Surface Heat Island (SHI) is a phenomenon whereby urban areas experience higher surface temperatures than the surrounding rural areas. The presence of the SHI in urban areas has a negative impact not only on city dwellers, but also on the environment and the economy. The development of SHI is often associated with patterns of land use and land cover in urban areas. Numerous methods exist that can be used to study SHI’s. Literature suggests that Land Surface Temperature (LST), derived from satellite imagery, is a proven method that produces reliable results. The aim of this study was to evaluate the SHI in King Williams Town by studying the relationship between land surface temperatures, land cover and land cover indices. The derived indices are the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built up Index (NDBI). These indices were selected because they are representative of the land cover scheme used in the research study. This study was conducted in the King Williams town area between the years 1995 and 2018 the land surface temperature was derived from Landsat ETM + high thermal band data. The findings from this study provide an idea on the correlation between satellite derived land surface temperature and the land modification which occurred during the urbanization of King Williams Town during a 23 year period between1995 and 2018. The built up land category was the most influential in the development of high land surface temperature levels , vegetation had an opposite effect as a series of data sets illustrated that vegetated areas had a iv cooling effect on the surface. Water bodies in the study area had an insignificant effect on the Surface temperature levels while the grass lands weren’t as cooling as the vegetation but provided a cooling environment in the study area .The spatial distribution of areas of high surface temperature (hot spots) was discovered to be concentrated in the urban areas of the study area which is in the northwest region of the study area and correlates to the land cover and land cover indices associated with built up and artificial surfaces. The cooler areas or patches of land with lower values of land surface temperature were distributed on the outskirts of the study area away from the CBD and residential areas. This was the case because of the high concentration of vegetation and thicker grass lands in those regions.
- Full Text:
- Date Issued: 2020
Synthesis and application of coal fly ash supported C doped TiO2/SnO2 photocatalyst in water treatment
- Authors: Sambakanya, Siyasanga
- Date: 2020
- Subjects: Photocatalysis
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: http://hdl.handle.net/10353/18838 , vital:42869
- Description: Coal fly ash supported carbon doped titanium dioxide/tin oxide (C doped TiO2-SnO2/CFA) nanoparticles were successfully synthesised using a sol gel method and calcined at 550 °C. The crystal structure, optical properties, morphology and other properties were analysed using XRD, UV-Vis, FTIR, TEM, SEM, DRS and EDX. SEM analysis showed that the nanoparticles (NPs) of C doped TiO2-SnO2/CFA were quasi spherical. XRD showed that C doped TiO2-SnO2/CFA nanoparticles were polycrystalline and consisted of both rutile and anatase phases. TEM analysis also displayed small NPs of C-TiO2-SnO2/CFA (12.62 nm) than TiO2 (16.19 nm) and SnO2 (19.98 nm). DRS revealed reduced band gap of C-TiO2 (2.78 eV) than TiO2 (3.19 eV) after doping. The photocatalytic efficiency of the prepared C-TiO2-SnO2/CFA nanoparticles was determined using methyl orange (MO) and methylene blue dye (MB) as standard dyes in the photodegradation as well as lead and mercury in the photoreduction of lead and mercury ions in water. The degradation experiments were carried under natural solar irradiation and UV light. The photodegradation experiments carried under visible light showed excellent photodegradation of MO & MB in water. This is a good indication that doping was successful as it imparted visible light activity in the C-TiO2-SnO2/CFA NPs. The photocatalyst efficiency was further tested while varying parameters including photocatalyst load, pH, and initial pollutant concentration in the photodegradation of MO & MB as well as in photoreduction of Pb2+ and Hg2+ in water to establish optimum operating conditions. The degradation rate of MO & MB increased when photocatalyst loading increased. When the pH was increased, the photocatalytic efficiency of the prepared photocatalyst towards methyl orange was reduced; however methylene blue degradation increased with increase in pH. The reduction of Pb2+ also increased with increasing pH whereas that of Hg2+ increased with decreasing pH. It was found that photodegradation was directly proportional to and photoreduction was inversely proportional to initial pollutant concentration.
- Full Text:
- Date Issued: 2020
- Authors: Sambakanya, Siyasanga
- Date: 2020
- Subjects: Photocatalysis
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: http://hdl.handle.net/10353/18838 , vital:42869
- Description: Coal fly ash supported carbon doped titanium dioxide/tin oxide (C doped TiO2-SnO2/CFA) nanoparticles were successfully synthesised using a sol gel method and calcined at 550 °C. The crystal structure, optical properties, morphology and other properties were analysed using XRD, UV-Vis, FTIR, TEM, SEM, DRS and EDX. SEM analysis showed that the nanoparticles (NPs) of C doped TiO2-SnO2/CFA were quasi spherical. XRD showed that C doped TiO2-SnO2/CFA nanoparticles were polycrystalline and consisted of both rutile and anatase phases. TEM analysis also displayed small NPs of C-TiO2-SnO2/CFA (12.62 nm) than TiO2 (16.19 nm) and SnO2 (19.98 nm). DRS revealed reduced band gap of C-TiO2 (2.78 eV) than TiO2 (3.19 eV) after doping. The photocatalytic efficiency of the prepared C-TiO2-SnO2/CFA nanoparticles was determined using methyl orange (MO) and methylene blue dye (MB) as standard dyes in the photodegradation as well as lead and mercury in the photoreduction of lead and mercury ions in water. The degradation experiments were carried under natural solar irradiation and UV light. The photodegradation experiments carried under visible light showed excellent photodegradation of MO & MB in water. This is a good indication that doping was successful as it imparted visible light activity in the C-TiO2-SnO2/CFA NPs. The photocatalyst efficiency was further tested while varying parameters including photocatalyst load, pH, and initial pollutant concentration in the photodegradation of MO & MB as well as in photoreduction of Pb2+ and Hg2+ in water to establish optimum operating conditions. The degradation rate of MO & MB increased when photocatalyst loading increased. When the pH was increased, the photocatalytic efficiency of the prepared photocatalyst towards methyl orange was reduced; however methylene blue degradation increased with increase in pH. The reduction of Pb2+ also increased with increasing pH whereas that of Hg2+ increased with decreasing pH. It was found that photodegradation was directly proportional to and photoreduction was inversely proportional to initial pollutant concentration.
- Full Text:
- Date Issued: 2020
Synthesis and characterization of binary and ternary palladium alloys for use as alternative counter electrode catalysts in dye sensitized solar cells
- Authors: Zingwe, Nyengerai Hillary
- Date: 2020
- Subjects: Electrocatalysis Chemistry
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: http://hdl.handle.net/10353/18513 , vital:42580
- Description: The dye sensitized solar cell counter electrode facilitates the regeneration of the dye molecules thereby ensuring the provision of higher sunlight to electricity conversion efficiency. The standard platinum electrode suffers from low efficiency due to corrosion by the redox mediator as well as being extremely expensive due to high demand. As an alternative this research study illustrates the efforts undertaken to replace the standard platinum counter electrode with palladium alloy counter electrodes. Application of palladium alloys ensures sustenance of high catalytic activity by palladium which is as effective as platinum. Although palladium is equally as expensive as platinum, its application in the form of alloys minimizes the amount required to produce an effective counter electrode to 0.001-0.004 moles thereby ensuring the provision of high efficiency at a lower cost. Furthermore, charge transfer from the other alloyed elements to the palladium atom increases active sites leading to higher catalytic activity than platinum. Additionally, changes in crystal structure due to alloying enhances resistance to corrosion thus enabling the longevity of the alloy counter electrode in the electrolyte ___________________________________________________________________________ Electrochemical analysis was conducted to determine the catalytic functionality of the developed alloys in cobalt, ferrocene and iodine redox mediators. The binary (PdNi-reduced graphene oxide (rGO) and PdCo-rGO) and ternary (PdNiCo-rGO) palladium alloys were fabricated via a hydrothermal method. In order to determine the composition which could provide the maximum activity, optimization was conducted through variation of the molar ratios of the precursor solutions. The properties of the synthesized palladium alloys were determined using various techniques including x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The developed alloys were observed to comprise of palladium, nickel, cobalt, and carbon atoms. The particles were spherical in nature for all the unsupported alloys with the carbon supported alloys exhibiting spherical particle wholly surrounded by graphene sheets. Cyclic voltammetry and electrochemical impedance spectroscopy analysis showed that the carbon supported alloys PdNi-rGO, PdCo-rGO and PdNiCo-rGO produced the highest catalytic activities due to the synergy between their respective alloys and the incorporated reduced graphene oxide. The high catalytic effectiveness of these alloys yielded power conversion efficiency in the order PdNiCo-rGO (9.01) > PdNi-rGO (8.4.%) > PdCo-rGO (6.56%) > Pt (5.7%) which were better than the platinum efficiency in the cobalt redox mediator. The higher efficiency in the cobalt redox mediator relative to the iodine electrolyte illustrates that they are viable alternatives to the, corrosive and volatile iodine. Obtained results show that, the high recombination rates between the photogenerated electrons and the oxidized dye molecule which have been reported to reduce power conversion efficiency in one electron redox mediators did not affect the performance of the cell. However, these higher recombination rates affected the ferrocene electrolyte leading to extremely poor efficiency metrics. The obtained results indicated that reduced graphene oxide supported PdNi-rGO, PdNiCo-rGO as well as the unsupported PdNi3 alloys could successfully be implemented as substitutes to the platinum counter electrode in dye sensitized solar cells. The application of the palladium alloys is vital for improving stability and power conversion efficiency, as well as reducing cost.
- Full Text:
- Date Issued: 2020
- Authors: Zingwe, Nyengerai Hillary
- Date: 2020
- Subjects: Electrocatalysis Chemistry
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: http://hdl.handle.net/10353/18513 , vital:42580
- Description: The dye sensitized solar cell counter electrode facilitates the regeneration of the dye molecules thereby ensuring the provision of higher sunlight to electricity conversion efficiency. The standard platinum electrode suffers from low efficiency due to corrosion by the redox mediator as well as being extremely expensive due to high demand. As an alternative this research study illustrates the efforts undertaken to replace the standard platinum counter electrode with palladium alloy counter electrodes. Application of palladium alloys ensures sustenance of high catalytic activity by palladium which is as effective as platinum. Although palladium is equally as expensive as platinum, its application in the form of alloys minimizes the amount required to produce an effective counter electrode to 0.001-0.004 moles thereby ensuring the provision of high efficiency at a lower cost. Furthermore, charge transfer from the other alloyed elements to the palladium atom increases active sites leading to higher catalytic activity than platinum. Additionally, changes in crystal structure due to alloying enhances resistance to corrosion thus enabling the longevity of the alloy counter electrode in the electrolyte ___________________________________________________________________________ Electrochemical analysis was conducted to determine the catalytic functionality of the developed alloys in cobalt, ferrocene and iodine redox mediators. The binary (PdNi-reduced graphene oxide (rGO) and PdCo-rGO) and ternary (PdNiCo-rGO) palladium alloys were fabricated via a hydrothermal method. In order to determine the composition which could provide the maximum activity, optimization was conducted through variation of the molar ratios of the precursor solutions. The properties of the synthesized palladium alloys were determined using various techniques including x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The developed alloys were observed to comprise of palladium, nickel, cobalt, and carbon atoms. The particles were spherical in nature for all the unsupported alloys with the carbon supported alloys exhibiting spherical particle wholly surrounded by graphene sheets. Cyclic voltammetry and electrochemical impedance spectroscopy analysis showed that the carbon supported alloys PdNi-rGO, PdCo-rGO and PdNiCo-rGO produced the highest catalytic activities due to the synergy between their respective alloys and the incorporated reduced graphene oxide. The high catalytic effectiveness of these alloys yielded power conversion efficiency in the order PdNiCo-rGO (9.01) > PdNi-rGO (8.4.%) > PdCo-rGO (6.56%) > Pt (5.7%) which were better than the platinum efficiency in the cobalt redox mediator. The higher efficiency in the cobalt redox mediator relative to the iodine electrolyte illustrates that they are viable alternatives to the, corrosive and volatile iodine. Obtained results show that, the high recombination rates between the photogenerated electrons and the oxidized dye molecule which have been reported to reduce power conversion efficiency in one electron redox mediators did not affect the performance of the cell. However, these higher recombination rates affected the ferrocene electrolyte leading to extremely poor efficiency metrics. The obtained results indicated that reduced graphene oxide supported PdNi-rGO, PdNiCo-rGO as well as the unsupported PdNi3 alloys could successfully be implemented as substitutes to the platinum counter electrode in dye sensitized solar cells. The application of the palladium alloys is vital for improving stability and power conversion efficiency, as well as reducing cost.
- Full Text:
- Date Issued: 2020
Synthesis and characterization of MXS (M = Mo & V) and carbon supported MXS nanocomposites as Pt-free counter electrodes for electrode for DSSC application
- Authors: Bede, Asanda
- Date: 2020
- Subjects: Voltammetry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18599 , vital:42612
- Description: It has been reported that the morphology, crystalline phase composition and electrochemical properties of counter electrode materials such MxS (Mo, V) and carbon supported MxS (Mo, V) composite nanomaterials was of considerable importance because it governs the efficiency of many photon assisted chemical and physical reactions in dye sensitized solar cells (DSSCs). The efficiency of DSSCs with composite counter electrode materials is reliant on the stability of the photochemistry reactions which can be optimized by appropriate doping levels of the composite materials. Moreover, the microstructure such as surface area, distribution of the MxS (Mo, V) and carbon supported MxS (Mo, V) composite nanomaterials, and the stability of the electrostatic bonds between the MxS (Mo, V) with the carbon support also play a significant role in the performance of the DSSCs. This work evaluates the effect of different mole ratios of the MxS (Mo, V) and carbon supported MxS (Mo, V) composite nanomaterials on the morphological, structural and electrochemical properties of the composite materials. MoS2 nanoflakes nanostructures have been synthesized by hydrothermal technique using sodium orthovanadate (Na2MoO4) as precursor. In this work Carbon supported MoS2 NFs have been prepared by physically/chemically mixing different mole ratios of MoS2 NFs with multi-walled carbon nanotubes (MWCNTs) and polyvinylidene in N-methyl-2-pyrrolidinone. The morphological, structural and electrochemical properties of the composite counter electrode materials have been investigated using SEM, XRD FTIR, TEM, RS and CV. SEM analysis has revealed the presence of large MoS2 nanoflakes (NFs) as synthesized. SEM analysis has also revealed significant change in the surface morphology of carbon supported MoS2 composite nanostructures with the change in the mole ratio of the MoS2 NFs and carbon support multi-walled carbon nanotubes. Structural analysis through HRTEM analysis revealed a d-spacing of 0.65 nm with a corresponding (002) lattice plane belonging to a trigonal crystalline phase of MoS2. Also, HRTEM analysis has revealed d-spacing of 0.291 nm corresponding to 002 plane of MWCNTs. Raman spectroscopy has revealed Characteristic Raman vibration frequencies and symmetries at 264.6 cm-1(Eg), 354.2 cm-1 (Ag ) belonging trigonal phase of MoS2 (1T-MoS2). FTIR analysis has revealed a narrow peak at 457.6 cm-1 due Mo-S vibration bond. This observation confirms the success of synthesis of MoS2 nanostructures. Cyclic voltammetry (CV), charge-discharge (CD) and electrochemical impedance spectroscopy (EIS) measurements have revealed that the ratio 6:3:1 have shown to be optimum ratio due to its large reduction rate compared to pristine MoS2 NFs and other carbon supported MoS2 NFs. Calculated Rreduction for the carbon supported MoS2 NFs is the order 3:6:1>1:8:1>6:3:1>8:1:1 indicating the trend of ratio 3:6:1 appeared to have higher reduction rate than the rest of the material and it had far less ΔEpp than the rest of other ratios. All CV curves for both pristine MoS2 NFs and carbon supported MoS2 NFs confirmed a distinct Faradic characteristic. The VS2 nanosheets (NSs) and carbon supported VS2 NSs were also effectively synthesized via hydrothermal method. The SEM micrographs for VS2 NSs and carbon supported VS2 NSs samples reveals level increased. Furthermore, SEM-EDX analysis have confirmed the presence of V and S as well as C and O on carbon supported VS2 nanocomposites, and it clearly shown a gradually blending as the ratios increases. The structural studies through XRD analysis have revealed peaks at 2θ angles of 15.4◦, 28.2◦, 34.2◦, 36.2◦, 43.3◦,48.3◦, 54.4◦, 57.7◦ and 66.2◦ which correspond to the lattice planes (001), (002), (100), (011), (102), (003), (110), (103) and (201) belonging to hexagonal VS2 (H-VS2) crystalline phase as per JCPDS card 36-1139. The HRTEM have revealed that the VS2 NSs have an edge to edge length of ~ 0.294 – 1.248 µm. Also, HRTEM micrographs of VS2 NSs have revealed interplanar d spacing of 0.571 nm belonging to the (001) lattice plane of hexagonal VS2 (H-VS2) structure. FTIR analysis have shown a peak at 558 cm-1 attributed to V-S which is evident that sulfur has bonded with the metal (V) and is in agreement with EDS. CV, CD and EIS measurements have shown that the ratio 1:8:1 is more superior to VS2 NSs and other carbon supported VS2 NSs. Based on Rreduction for the carbon supported nanosheets VS2 nanosheets are ordered as 1:8:1>3:6:1>6:3:1>8:1:1. Carbon supported VS2 NSs of the mole ratio 1:8:1 showed a small resistance of 0.32 Ω. This is further evidence that the carbon supported VS2 NSs of the mole ratio 1:8:1 in addition to revealing excellent catalytic behaviour is also more chemically stable and has good conductivity properties._________
- Full Text:
- Date Issued: 2020
- Authors: Bede, Asanda
- Date: 2020
- Subjects: Voltammetry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18599 , vital:42612
- Description: It has been reported that the morphology, crystalline phase composition and electrochemical properties of counter electrode materials such MxS (Mo, V) and carbon supported MxS (Mo, V) composite nanomaterials was of considerable importance because it governs the efficiency of many photon assisted chemical and physical reactions in dye sensitized solar cells (DSSCs). The efficiency of DSSCs with composite counter electrode materials is reliant on the stability of the photochemistry reactions which can be optimized by appropriate doping levels of the composite materials. Moreover, the microstructure such as surface area, distribution of the MxS (Mo, V) and carbon supported MxS (Mo, V) composite nanomaterials, and the stability of the electrostatic bonds between the MxS (Mo, V) with the carbon support also play a significant role in the performance of the DSSCs. This work evaluates the effect of different mole ratios of the MxS (Mo, V) and carbon supported MxS (Mo, V) composite nanomaterials on the morphological, structural and electrochemical properties of the composite materials. MoS2 nanoflakes nanostructures have been synthesized by hydrothermal technique using sodium orthovanadate (Na2MoO4) as precursor. In this work Carbon supported MoS2 NFs have been prepared by physically/chemically mixing different mole ratios of MoS2 NFs with multi-walled carbon nanotubes (MWCNTs) and polyvinylidene in N-methyl-2-pyrrolidinone. The morphological, structural and electrochemical properties of the composite counter electrode materials have been investigated using SEM, XRD FTIR, TEM, RS and CV. SEM analysis has revealed the presence of large MoS2 nanoflakes (NFs) as synthesized. SEM analysis has also revealed significant change in the surface morphology of carbon supported MoS2 composite nanostructures with the change in the mole ratio of the MoS2 NFs and carbon support multi-walled carbon nanotubes. Structural analysis through HRTEM analysis revealed a d-spacing of 0.65 nm with a corresponding (002) lattice plane belonging to a trigonal crystalline phase of MoS2. Also, HRTEM analysis has revealed d-spacing of 0.291 nm corresponding to 002 plane of MWCNTs. Raman spectroscopy has revealed Characteristic Raman vibration frequencies and symmetries at 264.6 cm-1(Eg), 354.2 cm-1 (Ag ) belonging trigonal phase of MoS2 (1T-MoS2). FTIR analysis has revealed a narrow peak at 457.6 cm-1 due Mo-S vibration bond. This observation confirms the success of synthesis of MoS2 nanostructures. Cyclic voltammetry (CV), charge-discharge (CD) and electrochemical impedance spectroscopy (EIS) measurements have revealed that the ratio 6:3:1 have shown to be optimum ratio due to its large reduction rate compared to pristine MoS2 NFs and other carbon supported MoS2 NFs. Calculated Rreduction for the carbon supported MoS2 NFs is the order 3:6:1>1:8:1>6:3:1>8:1:1 indicating the trend of ratio 3:6:1 appeared to have higher reduction rate than the rest of the material and it had far less ΔEpp than the rest of other ratios. All CV curves for both pristine MoS2 NFs and carbon supported MoS2 NFs confirmed a distinct Faradic characteristic. The VS2 nanosheets (NSs) and carbon supported VS2 NSs were also effectively synthesized via hydrothermal method. The SEM micrographs for VS2 NSs and carbon supported VS2 NSs samples reveals level increased. Furthermore, SEM-EDX analysis have confirmed the presence of V and S as well as C and O on carbon supported VS2 nanocomposites, and it clearly shown a gradually blending as the ratios increases. The structural studies through XRD analysis have revealed peaks at 2θ angles of 15.4◦, 28.2◦, 34.2◦, 36.2◦, 43.3◦,48.3◦, 54.4◦, 57.7◦ and 66.2◦ which correspond to the lattice planes (001), (002), (100), (011), (102), (003), (110), (103) and (201) belonging to hexagonal VS2 (H-VS2) crystalline phase as per JCPDS card 36-1139. The HRTEM have revealed that the VS2 NSs have an edge to edge length of ~ 0.294 – 1.248 µm. Also, HRTEM micrographs of VS2 NSs have revealed interplanar d spacing of 0.571 nm belonging to the (001) lattice plane of hexagonal VS2 (H-VS2) structure. FTIR analysis have shown a peak at 558 cm-1 attributed to V-S which is evident that sulfur has bonded with the metal (V) and is in agreement with EDS. CV, CD and EIS measurements have shown that the ratio 1:8:1 is more superior to VS2 NSs and other carbon supported VS2 NSs. Based on Rreduction for the carbon supported nanosheets VS2 nanosheets are ordered as 1:8:1>3:6:1>6:3:1>8:1:1. Carbon supported VS2 NSs of the mole ratio 1:8:1 showed a small resistance of 0.32 Ω. This is further evidence that the carbon supported VS2 NSs of the mole ratio 1:8:1 in addition to revealing excellent catalytic behaviour is also more chemically stable and has good conductivity properties._________
- Full Text:
- Date Issued: 2020
The characteristics and trends of rainfall on sub-Antarctic Marion Island and associated air circulation patterns
- Authors: Mapuka, Fortunate Nomsa
- Date: 2020
- Language: English
- Type: Thesis , Masters , MSc(Geography)
- Identifier: http://hdl.handle.net/10353/18698 , vital:42725
- Description: Marion Island (46°54ʹS, 37°45ʹE) located in the Southern Ocean possesses one of the most oceanic climates on earth and sensitive to climate change. Climatologically, the sub-Antarctic is inadequately represented in the climate literature and this research therefore attempts to establish the recent changes that have occurred on Marion Island with regards to annual rainfall totals, monthly rainfall, rain days and non-rain days during the period from 1980 to 2018. This study found that annual rainfall has decreased by 24% from 2196.7 mm to 1678.57 mm from 1980 to 2018 and that the last decade (2010-2018) is the driest on record. The decrease in annual rainfall on Marion Island can be directly linked to the decreases recorded in monthly and daily rainfall. Rainfall in autumn has reduced by 35% over the last 40 years and the decrease in autumn rainfall is in part directly related to an increase in anticyclonic air circulation during which Marion Island is not influenced by any mid-latitudinal depressions. The frequency of rain days measured on Marion Island significantly decreased. Daily rainfall measuring less than 5 mm of rain a day contribute 50% of the total number of rain days. However, these high frequency low depth rainfall days contribute very little rainfall to annual totals. On Marion Island rain days that measure 10 mm and above contribute 65% of the total annual rainfall and it is also these type of high magnitude rain days that have significantly decreased since 1980. Multi-day consecutive rain events contribute the greatest proportion of rainfall to the annual rainfall totals (~40%). Linear statistics shows that the contribution to rainfall amount from these multi-day rainfall has halved since 1980. The frequency of non-rain days and consecutive non-rain days have significantly increased. The increased frequency of anticyclonic air circulation over Marion Island and the decrease of the traveling low-pressure systems affecting Marion Island are the probable cause of the increase in non-rain days. It is suggested that this increase in consecutive non-rain days has the most significant impact on the island’s biodiversity and landscape
- Full Text:
- Date Issued: 2020
- Authors: Mapuka, Fortunate Nomsa
- Date: 2020
- Language: English
- Type: Thesis , Masters , MSc(Geography)
- Identifier: http://hdl.handle.net/10353/18698 , vital:42725
- Description: Marion Island (46°54ʹS, 37°45ʹE) located in the Southern Ocean possesses one of the most oceanic climates on earth and sensitive to climate change. Climatologically, the sub-Antarctic is inadequately represented in the climate literature and this research therefore attempts to establish the recent changes that have occurred on Marion Island with regards to annual rainfall totals, monthly rainfall, rain days and non-rain days during the period from 1980 to 2018. This study found that annual rainfall has decreased by 24% from 2196.7 mm to 1678.57 mm from 1980 to 2018 and that the last decade (2010-2018) is the driest on record. The decrease in annual rainfall on Marion Island can be directly linked to the decreases recorded in monthly and daily rainfall. Rainfall in autumn has reduced by 35% over the last 40 years and the decrease in autumn rainfall is in part directly related to an increase in anticyclonic air circulation during which Marion Island is not influenced by any mid-latitudinal depressions. The frequency of rain days measured on Marion Island significantly decreased. Daily rainfall measuring less than 5 mm of rain a day contribute 50% of the total number of rain days. However, these high frequency low depth rainfall days contribute very little rainfall to annual totals. On Marion Island rain days that measure 10 mm and above contribute 65% of the total annual rainfall and it is also these type of high magnitude rain days that have significantly decreased since 1980. Multi-day consecutive rain events contribute the greatest proportion of rainfall to the annual rainfall totals (~40%). Linear statistics shows that the contribution to rainfall amount from these multi-day rainfall has halved since 1980. The frequency of non-rain days and consecutive non-rain days have significantly increased. The increased frequency of anticyclonic air circulation over Marion Island and the decrease of the traveling low-pressure systems affecting Marion Island are the probable cause of the increase in non-rain days. It is suggested that this increase in consecutive non-rain days has the most significant impact on the island’s biodiversity and landscape
- Full Text:
- Date Issued: 2020
The effect of feeding varying inclusion levels of velvet bean (Mucuna pruriens) seed meal on growth performance and physicochemical attributes of broiler chicken
- Authors: Mthana, Makiwa Simeon
- Date: 2020
- Subjects: Legumes Broilers (Chickens) Chickens -- Feeding and feeds
- Language: English
- Type: Thesis , Masters/Doctoral , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/12032 , vital:39129
- Description: This study was conducted to determine the effect of feeding varying inclusion levels of velvet bean (Mucuna pruriens) seed meal (VBSM) on growth performance and physicochemical attributes of broiler chicken. Mucuna pruriens seed is an indigenous legume seed commonly found in tropical and sub-tropical areas; however, it can also be planted and cultivated. It is a viable source of dietary protein with an average concentration of 33.4%. Soybean is expensive. In addition, the South African production levels do not meet the current demand; hence the majority of soybean oilcake is imported. Recently, consumers have been conscious of the quality of chicken meat from both local and international producers. Therefore, there is a need to explore velvet bean that can grow in poorly fertilised and low rainfall areas. The study was conducted at Fort Cox Agriculture and Forestry Training Institute. One hundred and twelve (112) Cobb broilers were used, with an average weight of 45.2g. Four diets were formulated to be iso-caloric and iso-nitrogenous comprising velvet beans at 0, 10, 15 and 20 % (T1, T2, T3 and T4). The broilers were reared for 42 days with 35 days on experimental diets. Feed intake, body weight gain, feed conversion ratio, mortality, final body weight, carcass weight, and dressing percentage were determined. At day 42, twenty birds per treatment were randomly selected and fasted for five hours with water offered ad libitum. After slaughter the meat pH24, colour (L*, a*, b*), Warner-Bratzler shear force (WBSF), thawing loss (TL), and cooking loss (CL) measurements were performed on 80 breast and 80 thigh muscles. The data for growth performance and physicochemical parameters was analysed using General Linear Model (GLM) procedure of SAS (SAS, 2006), mean separation was done using LSD test option of SAS. Daily feed intake, body weight gain, final weight and carcass weight of broilers from T1 were significantly higher (P < 0.05) from other iii treatments. Daily feed intake (DFI), and body weight gain (BWG) in T1 were also higher (P < 0.05) in both phase 1 and phase 2 compared to other treatments. Feed conversion ratio (FCR) was not influenced by diets (P > 0.05). High (P < 0.05) mortality was observed on broilers fed diet with 0% VBSM compared to those fed diets comprising of VBSM. The diets did not have an effect (P > 0.05) on thigh meat pH24, lightness, redness, and WBSF. Cooking loss (25.69%) was higher (P < 0.05) in thigh meat of broilers fed the control diet. Breasts shear force (14.20) was higher in T4. Cooking loss of breast meat from broilers on T1 and T2 was higher (P < 0.05) than those from other treatments. Breast meat colour (P > 0.05) was not influenced by diets. It can be concluded that the VBSM has an effect on feed intake, growth performance and mortality of broilers, except on FCR and dressing percentage. It was also concluded that the VBSM can be included in broiler diets up to the level of 15% without negatively affecting the quality of meat.
- Full Text:
- Date Issued: 2020
- Authors: Mthana, Makiwa Simeon
- Date: 2020
- Subjects: Legumes Broilers (Chickens) Chickens -- Feeding and feeds
- Language: English
- Type: Thesis , Masters/Doctoral , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/12032 , vital:39129
- Description: This study was conducted to determine the effect of feeding varying inclusion levels of velvet bean (Mucuna pruriens) seed meal (VBSM) on growth performance and physicochemical attributes of broiler chicken. Mucuna pruriens seed is an indigenous legume seed commonly found in tropical and sub-tropical areas; however, it can also be planted and cultivated. It is a viable source of dietary protein with an average concentration of 33.4%. Soybean is expensive. In addition, the South African production levels do not meet the current demand; hence the majority of soybean oilcake is imported. Recently, consumers have been conscious of the quality of chicken meat from both local and international producers. Therefore, there is a need to explore velvet bean that can grow in poorly fertilised and low rainfall areas. The study was conducted at Fort Cox Agriculture and Forestry Training Institute. One hundred and twelve (112) Cobb broilers were used, with an average weight of 45.2g. Four diets were formulated to be iso-caloric and iso-nitrogenous comprising velvet beans at 0, 10, 15 and 20 % (T1, T2, T3 and T4). The broilers were reared for 42 days with 35 days on experimental diets. Feed intake, body weight gain, feed conversion ratio, mortality, final body weight, carcass weight, and dressing percentage were determined. At day 42, twenty birds per treatment were randomly selected and fasted for five hours with water offered ad libitum. After slaughter the meat pH24, colour (L*, a*, b*), Warner-Bratzler shear force (WBSF), thawing loss (TL), and cooking loss (CL) measurements were performed on 80 breast and 80 thigh muscles. The data for growth performance and physicochemical parameters was analysed using General Linear Model (GLM) procedure of SAS (SAS, 2006), mean separation was done using LSD test option of SAS. Daily feed intake, body weight gain, final weight and carcass weight of broilers from T1 were significantly higher (P < 0.05) from other iii treatments. Daily feed intake (DFI), and body weight gain (BWG) in T1 were also higher (P < 0.05) in both phase 1 and phase 2 compared to other treatments. Feed conversion ratio (FCR) was not influenced by diets (P > 0.05). High (P < 0.05) mortality was observed on broilers fed diet with 0% VBSM compared to those fed diets comprising of VBSM. The diets did not have an effect (P > 0.05) on thigh meat pH24, lightness, redness, and WBSF. Cooking loss (25.69%) was higher (P < 0.05) in thigh meat of broilers fed the control diet. Breasts shear force (14.20) was higher in T4. Cooking loss of breast meat from broilers on T1 and T2 was higher (P < 0.05) than those from other treatments. Breast meat colour (P > 0.05) was not influenced by diets. It can be concluded that the VBSM has an effect on feed intake, growth performance and mortality of broilers, except on FCR and dressing percentage. It was also concluded that the VBSM can be included in broiler diets up to the level of 15% without negatively affecting the quality of meat.
- Full Text:
- Date Issued: 2020
The effect of muscle type and freezing on the evolution of physico-chemical properties during processing of South African biltong and its final textural properties
- Authors: Ngwendu, Nwabisa
- Date: 2020
- Subjects: Biltong Meat -- Quality -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12128 , vital:39154
- Description: The study investigated the effect of muscle type and freezing on evaluation of mass transfer during processing physico-chemical of South African biltong and its textural properties. In the first experimental phase of this study, mass transfers, physico-chemical and textural properties (hardness, cohesiveness, springiness, and chewiness) of commercially produced biltong from biceps femoris (BF) and semitendinosus (ST) (n=9) were measured. Biltong was dried at 30oC and 40% relative humidity until it had lost 50% of its initial weight. The initial moisture content, water activity (Aw) of BF muscles (74.3% and 0.992) were significantly lower compared those of ST muscles (75.4% and 0.994%). The fat content of BF (2.3%) muscles was higher (P<0.05) than in ST muscles (1.7%). The salt, weight and water gain for the BF muscle were 2.3%, -2.6% and -7.0% respectively and were significantly higher than those of ST muscles which were 2.1, -0.4 and -4.0, respectively. After drying, the moisture content, Aw, and pH were lower in BF (42.2, 0.886 and 5.29) than those of ST muscles (45.1, 0.911 and 5.42). The salt content was higher (P<0.05) in BF muscle than in ST. Among textural properties, hardness was significantly higher in biltong from the BF (233.0N), while the springiness was significantly lower compared to the ST muscle (178.2N). Therefore, it was concluded that the use of different muscles results in variation of biltong physicochemical characteristics. The second experiment investigated the effect of freezing and muscle type on mass transfers, lipid oxidation, physico-chemical and textural properties of biltong. In this experiment, the iii ST muscles were replaced with semimembranosus (SM) muscles. A total of 12 beef muscles were used, with six BF and six SM muscles frozen in a blast freezer at -40 oC till they reached -20oC; then they were transferred to -20oC for 14 days. The thawing loss for the BF and ST muscles was 1.3 and 2.4% respectively, but there were no significant (P>0.05) differences. The protein and salt content were significantly higher in frozen-thawed (24.3 and 0.13%) muscles than in fresh muscle (20.2 and 0.08%); whereas the fat content and pH were lower (P<0.05) in frozen-thawed (5.36) compared to fresh muscles (5.51). Between muscles, the moisture, salt content, and pH were higher in BF muscles than in SM muscles (73.2, 0.12% and 5.49). Aw was affected by the interaction between freezing and muscle type, with frozenthawed SM having lower Aw (0.990). During salting, salt, weight and water gain did not show any differences (P<0.05). There were no major significant differences after salting. There were lower TBARS and pH in frozen-thawed (1.5mgMDA/kg and 5.15) muscles than in fresh muscles (3.3mgMDA/kg and 5.19) as well as in SM muscles (1.8mgMDA/kg and 5.16) than in BF muscles (3.0mgMDA/kg and 5.19). The moisture was significantly lower in frozen-thawed SM (68.1%) than in fresh SM, BF and frozen-thawed BF (69.3,70.5 and 71.7%) after salting. On the final product, the interaction between muscle type and freezing affected the moisture content, TBARS, chewiness and the springiness of biltong, with the biltong from fresh SM (39.8%) having significantly lower moisture content compared frozenthawed BF and ST muscles as well fresh BF muscles (42.8% in average). The TBARS were higher in biltong from fresh BF muscles (5.1mgMDA/kg) compared to other muscles. Furthermore, the chewiness and springiness were higher (P<0.05) in biltong produced from SM frozen-thawed muscles (327.7N and 1.5). The WBSF was higher in biltong from the BF muscles (108.8N) than in the biltong from SM (80.1) but it was not affected by the freezing effect (P>0.05). Freezing did not show any major differences in biltong. iv The third experiment was conducted to determine the effect of freezing African buffalo carcasses on weight loss during salting, physico-chemical and textural properties of biltong. Five muscles (ST, SM, BF, LTL, and RF) were randomly selected from 30 carcasses (15 frozen-thawed and 15 fresh), cut along the grain, traditionally salted and dried at 26oC till they lost 45-50% of their initial weight. The salting weight loss was higher in frozen-thawed muscles (-1.45%) than in fresh muscles (-0.89%). The freezing treatment affected the physico-chemical properties of the biltong. The biltong produced from frozen-thawed muscles showed significantly higher protein and ash (47.6 and 7.6%) compared to fresh (43.9 and 7.1); whereas the moisture, fat, pH and Aw were lower (43.7, 2.1, 0.870 and 5.30, respectively) compared to those of biltong from fresh muscles (45.5%, 2.9%, 0.890 and 5.38). The moisture, pH and fat content were further affected by muscle type. The interactive effect was observed in salt content, with RF frozen-thawed showing higher salt content (8.2%) compared to all other muscles. The hardness and WBSF were significantly higher (P<0.05) in biltong frozen-thawed (204.1N and 135.0N) than in fresh muscles (146.2N and 113.1N). Moreover, the chewiness and springiness were affected (P<0.05) by muscle type, with RF muscle having higher springiness 0.89 and chewiness 171.1N than all the other muscles. Therefore, it can be concluded that freezing buffalo carcasses significantly influenced the quality characteristics of biltong. The fourth experiment studied the effect of drying methods on physico-chemical properties of traditional biltong produced from African buffalo muscles. The BF and SM muscles were randomly selected from 15 fresh carcasses, cut into strips, salted and divided into two batches per muscle. The first batch of each muscle type was dried in the ambient-air drier at 22oC average and the second batch in the cabinet drier at 26 oC till 45-50% weight loss. No differences (P>0.05) were observed in salting weight loss between the drying method and muscle type. The protein content was significantly higher in SM (46%) muscles compared to v BF (43%) but there was no effect (P>0.05) caused by the drying method. The interactions between the muscle type and drying method affected the fat content, with biltong from airdried BF muscles having significant lower (2.1%) fat content. There were no significant differences in other physico-chemical properties of biltong, with moisture content, salt, ash content, Aw and pH being 45.0%, 5.13%, 44.8%, 7.3%, 2.7%, 0.885 and 5.61 on average, respectively. Overall, the findings of the study show that freezing does have a significant effect on the final quality of biltong. However, it can be concluded that a significant effect on the physico-chemical properties of biltong depends on the changes of mass transfers during salting and drying.
- Full Text:
- Date Issued: 2020
- Authors: Ngwendu, Nwabisa
- Date: 2020
- Subjects: Biltong Meat -- Quality -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12128 , vital:39154
- Description: The study investigated the effect of muscle type and freezing on evaluation of mass transfer during processing physico-chemical of South African biltong and its textural properties. In the first experimental phase of this study, mass transfers, physico-chemical and textural properties (hardness, cohesiveness, springiness, and chewiness) of commercially produced biltong from biceps femoris (BF) and semitendinosus (ST) (n=9) were measured. Biltong was dried at 30oC and 40% relative humidity until it had lost 50% of its initial weight. The initial moisture content, water activity (Aw) of BF muscles (74.3% and 0.992) were significantly lower compared those of ST muscles (75.4% and 0.994%). The fat content of BF (2.3%) muscles was higher (P<0.05) than in ST muscles (1.7%). The salt, weight and water gain for the BF muscle were 2.3%, -2.6% and -7.0% respectively and were significantly higher than those of ST muscles which were 2.1, -0.4 and -4.0, respectively. After drying, the moisture content, Aw, and pH were lower in BF (42.2, 0.886 and 5.29) than those of ST muscles (45.1, 0.911 and 5.42). The salt content was higher (P<0.05) in BF muscle than in ST. Among textural properties, hardness was significantly higher in biltong from the BF (233.0N), while the springiness was significantly lower compared to the ST muscle (178.2N). Therefore, it was concluded that the use of different muscles results in variation of biltong physicochemical characteristics. The second experiment investigated the effect of freezing and muscle type on mass transfers, lipid oxidation, physico-chemical and textural properties of biltong. In this experiment, the iii ST muscles were replaced with semimembranosus (SM) muscles. A total of 12 beef muscles were used, with six BF and six SM muscles frozen in a blast freezer at -40 oC till they reached -20oC; then they were transferred to -20oC for 14 days. The thawing loss for the BF and ST muscles was 1.3 and 2.4% respectively, but there were no significant (P>0.05) differences. The protein and salt content were significantly higher in frozen-thawed (24.3 and 0.13%) muscles than in fresh muscle (20.2 and 0.08%); whereas the fat content and pH were lower (P<0.05) in frozen-thawed (5.36) compared to fresh muscles (5.51). Between muscles, the moisture, salt content, and pH were higher in BF muscles than in SM muscles (73.2, 0.12% and 5.49). Aw was affected by the interaction between freezing and muscle type, with frozenthawed SM having lower Aw (0.990). During salting, salt, weight and water gain did not show any differences (P<0.05). There were no major significant differences after salting. There were lower TBARS and pH in frozen-thawed (1.5mgMDA/kg and 5.15) muscles than in fresh muscles (3.3mgMDA/kg and 5.19) as well as in SM muscles (1.8mgMDA/kg and 5.16) than in BF muscles (3.0mgMDA/kg and 5.19). The moisture was significantly lower in frozen-thawed SM (68.1%) than in fresh SM, BF and frozen-thawed BF (69.3,70.5 and 71.7%) after salting. On the final product, the interaction between muscle type and freezing affected the moisture content, TBARS, chewiness and the springiness of biltong, with the biltong from fresh SM (39.8%) having significantly lower moisture content compared frozenthawed BF and ST muscles as well fresh BF muscles (42.8% in average). The TBARS were higher in biltong from fresh BF muscles (5.1mgMDA/kg) compared to other muscles. Furthermore, the chewiness and springiness were higher (P<0.05) in biltong produced from SM frozen-thawed muscles (327.7N and 1.5). The WBSF was higher in biltong from the BF muscles (108.8N) than in the biltong from SM (80.1) but it was not affected by the freezing effect (P>0.05). Freezing did not show any major differences in biltong. iv The third experiment was conducted to determine the effect of freezing African buffalo carcasses on weight loss during salting, physico-chemical and textural properties of biltong. Five muscles (ST, SM, BF, LTL, and RF) were randomly selected from 30 carcasses (15 frozen-thawed and 15 fresh), cut along the grain, traditionally salted and dried at 26oC till they lost 45-50% of their initial weight. The salting weight loss was higher in frozen-thawed muscles (-1.45%) than in fresh muscles (-0.89%). The freezing treatment affected the physico-chemical properties of the biltong. The biltong produced from frozen-thawed muscles showed significantly higher protein and ash (47.6 and 7.6%) compared to fresh (43.9 and 7.1); whereas the moisture, fat, pH and Aw were lower (43.7, 2.1, 0.870 and 5.30, respectively) compared to those of biltong from fresh muscles (45.5%, 2.9%, 0.890 and 5.38). The moisture, pH and fat content were further affected by muscle type. The interactive effect was observed in salt content, with RF frozen-thawed showing higher salt content (8.2%) compared to all other muscles. The hardness and WBSF were significantly higher (P<0.05) in biltong frozen-thawed (204.1N and 135.0N) than in fresh muscles (146.2N and 113.1N). Moreover, the chewiness and springiness were affected (P<0.05) by muscle type, with RF muscle having higher springiness 0.89 and chewiness 171.1N than all the other muscles. Therefore, it can be concluded that freezing buffalo carcasses significantly influenced the quality characteristics of biltong. The fourth experiment studied the effect of drying methods on physico-chemical properties of traditional biltong produced from African buffalo muscles. The BF and SM muscles were randomly selected from 15 fresh carcasses, cut into strips, salted and divided into two batches per muscle. The first batch of each muscle type was dried in the ambient-air drier at 22oC average and the second batch in the cabinet drier at 26 oC till 45-50% weight loss. No differences (P>0.05) were observed in salting weight loss between the drying method and muscle type. The protein content was significantly higher in SM (46%) muscles compared to v BF (43%) but there was no effect (P>0.05) caused by the drying method. The interactions between the muscle type and drying method affected the fat content, with biltong from airdried BF muscles having significant lower (2.1%) fat content. There were no significant differences in other physico-chemical properties of biltong, with moisture content, salt, ash content, Aw and pH being 45.0%, 5.13%, 44.8%, 7.3%, 2.7%, 0.885 and 5.61 on average, respectively. Overall, the findings of the study show that freezing does have a significant effect on the final quality of biltong. However, it can be concluded that a significant effect on the physico-chemical properties of biltong depends on the changes of mass transfers during salting and drying.
- Full Text:
- Date Issued: 2020
The use of information and communication technologies in agricultural development in rural areas: case of smallholder farmers in Umzimvubu Local Municipality
- Authors: Makaula, Zimasa
- Date: 2020
- Subjects: Agricultural extension work , Information technology , Farms, Small -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , M Agric (Agric Extension)
- Identifier: http://hdl.handle.net/10353/11994 , vital:39125
- Description: Proper and timeous communication amongst different social development participants is one of the main driving factors for successful human progress. Different platforms have been used by different industries across the globe to ensure that useful information is shared with relevant structures at appropriate times. The global increase on use and availability of Information Communication Technologies (ICT’s) has prompted a thorough analysis and study of their relevance on different industries. Much of the increase has been observed mainly on highly urbanized areas, where the majority of the population is literate and who are above the poverty line. Some researchers have argued that the language used in some of the ICT’s is limited to the elite few, while others highlight cost implications in the use of these ICTs. The agricultural industry is not immune to the debates that relate to the development of ICTs, it is in most cases at the center, due to its diverse nature (in terms of participation) and close linkage to human development. There seems to be a correlation between ICT usage and the economies of scale in agricultural development, where smallholder farmers tend to use less of highly modernized ICTs, while commercial large scale farmers use more of the modernized ICTs. This disparity amongst farmers is exacerbated in many areas by the differing support systems employed by the public extension services. This study was initiated in order to study the usage and relevance of the ICTs by the smallholder farmers of the Umzimvubu Local Municipality of the Eastern Cape Province in South Africa. The research address the following research questions: 1. Which ICTs are owned by smallholder farmers of Umzimvubu local municipality? 2. Do smallholder farmers use ICTs to communicate agricultural information? 3. What are the types of ICT devices and services used by smallholder farmers for vi agricultural development? 4. What are the challenges faced by smallholder farmers when using ICTs to communicate agricultural information? A survey questionnaire was then developed to collect the relevant data from randomly selected six villages of Umzimvubu Local Municipality. The questionnaires structure employed both closed and open-ended questions that were administered using a face to face interview, conducted on the sample population in each village. The results indicated that the most common ICTs that were owned by smallholder farmers in the study area were: mobile phones (33%), televisions (TV) (28%), and radio (20%). The results also showed that communication amongst farmers (35%) and extension officers (35%) was the most notable use of mobile phone from the study area. The results also revealed that most smallholder farmers faced the following challenges when using ICTs to retrieve agricultural information; poor signal (40%), inconsistent broadcasting times for TV and radio agricultural programmes (35%), language barrier (15%) and lack of electricity (10%). The study, therefore, concludes that a majority of smallholder farmers from the study area own ICT devices necessary for rural agricultural development (mobile phones, TV and radio) that can be targeted by extension officers, policy makers, rural development implementing agencies and agro-industries to promote rural development. However, several challenges (language barrier, poor network signal and no electricity) limit the potential of these ICT devices and services from fully benefiting smallholder farmers.
- Full Text:
- Date Issued: 2020
- Authors: Makaula, Zimasa
- Date: 2020
- Subjects: Agricultural extension work , Information technology , Farms, Small -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , M Agric (Agric Extension)
- Identifier: http://hdl.handle.net/10353/11994 , vital:39125
- Description: Proper and timeous communication amongst different social development participants is one of the main driving factors for successful human progress. Different platforms have been used by different industries across the globe to ensure that useful information is shared with relevant structures at appropriate times. The global increase on use and availability of Information Communication Technologies (ICT’s) has prompted a thorough analysis and study of their relevance on different industries. Much of the increase has been observed mainly on highly urbanized areas, where the majority of the population is literate and who are above the poverty line. Some researchers have argued that the language used in some of the ICT’s is limited to the elite few, while others highlight cost implications in the use of these ICTs. The agricultural industry is not immune to the debates that relate to the development of ICTs, it is in most cases at the center, due to its diverse nature (in terms of participation) and close linkage to human development. There seems to be a correlation between ICT usage and the economies of scale in agricultural development, where smallholder farmers tend to use less of highly modernized ICTs, while commercial large scale farmers use more of the modernized ICTs. This disparity amongst farmers is exacerbated in many areas by the differing support systems employed by the public extension services. This study was initiated in order to study the usage and relevance of the ICTs by the smallholder farmers of the Umzimvubu Local Municipality of the Eastern Cape Province in South Africa. The research address the following research questions: 1. Which ICTs are owned by smallholder farmers of Umzimvubu local municipality? 2. Do smallholder farmers use ICTs to communicate agricultural information? 3. What are the types of ICT devices and services used by smallholder farmers for vi agricultural development? 4. What are the challenges faced by smallholder farmers when using ICTs to communicate agricultural information? A survey questionnaire was then developed to collect the relevant data from randomly selected six villages of Umzimvubu Local Municipality. The questionnaires structure employed both closed and open-ended questions that were administered using a face to face interview, conducted on the sample population in each village. The results indicated that the most common ICTs that were owned by smallholder farmers in the study area were: mobile phones (33%), televisions (TV) (28%), and radio (20%). The results also showed that communication amongst farmers (35%) and extension officers (35%) was the most notable use of mobile phone from the study area. The results also revealed that most smallholder farmers faced the following challenges when using ICTs to retrieve agricultural information; poor signal (40%), inconsistent broadcasting times for TV and radio agricultural programmes (35%), language barrier (15%) and lack of electricity (10%). The study, therefore, concludes that a majority of smallholder farmers from the study area own ICT devices necessary for rural agricultural development (mobile phones, TV and radio) that can be targeted by extension officers, policy makers, rural development implementing agencies and agro-industries to promote rural development. However, several challenges (language barrier, poor network signal and no electricity) limit the potential of these ICT devices and services from fully benefiting smallholder farmers.
- Full Text:
- Date Issued: 2020
Towards a reconstruction of Marion Island’s glacial history
- Authors: Rudolph, Elizabeth
- Date: 2020
- Subjects: Glacial landforms Geomorphological mapping
- Language: English
- Type: Thesis , Doctoral , PhD (Geography)
- Identifier: http://hdl.handle.net/10353/18531 , vital:42581
- Description: Southern Hemisphere glacial chronologies can provide valuable insights into interactions between glaciation and past climate changes. The sub-Antarctic Islands provide a valuable terrestrial record of glacial chronologies for the Southern Hemisphere, since they are unique, not only in size and topography, but also in oceanic situation when compared to other continental landmasses (e.g. Antarctica or Patagonia). On sub-Antarctic Marion Island, southern Indian Ocean, the exact timing and extent of the local Last Glacial Maximum is not yet known as glacial reconstructions have mostly been based on palynological proxies and relative-age dating techniques. This study presents 29 cosmogenic 36Cl exposure ages of deglaciated bedrock surfaces and moraine deposits from Marion Island. In addition, a comprehensive glacial-geomorphological map, which in conjunction with exposure ages provide improved temporal and spatial constraints for the island’s glacial history. Results show that the ice reached a local Last Glacial Maximum before 56 ka ago and retreated, with minor stillstands, until ~17 ka. This early deglaciation left island surfaces below 850 m a.s.l. ice-free after ~19 ka, and any subsequent advances during the Late Glacial or Holocene cooling periods would have been restricted to the interior. This glacial chronology is similar to that of some other sub-Antarctic Islands (e.g. the Kerguelen archipelago, Auckland and Campbell islands, and possibly South Georgia) and a number of other Southern Hemisphere glaciers (e.g. in Patagonia and New Zealand) and adds to evidence that suggest the Southern Hemisphere was in a glacial maximum earlier than the global LGM. A combination of climatic drivers such as declining temperatures, a northward migration of oceanic fronts and the Southern Hemisphere Westerly Winds (causing precipitation changes), as well as the physiography of Marion Island, created optimal conditions for glacier growth during Marine Isotope Stage 4 (MIS 4; ~65 ka ago) instead of the global LGM in MIS 2 (~18 ka). These findings redefine the glacial history of Marion Island, and have implications for future investigations on post-glacial landscape development and ecological succession.
- Full Text:
- Date Issued: 2020
- Authors: Rudolph, Elizabeth
- Date: 2020
- Subjects: Glacial landforms Geomorphological mapping
- Language: English
- Type: Thesis , Doctoral , PhD (Geography)
- Identifier: http://hdl.handle.net/10353/18531 , vital:42581
- Description: Southern Hemisphere glacial chronologies can provide valuable insights into interactions between glaciation and past climate changes. The sub-Antarctic Islands provide a valuable terrestrial record of glacial chronologies for the Southern Hemisphere, since they are unique, not only in size and topography, but also in oceanic situation when compared to other continental landmasses (e.g. Antarctica or Patagonia). On sub-Antarctic Marion Island, southern Indian Ocean, the exact timing and extent of the local Last Glacial Maximum is not yet known as glacial reconstructions have mostly been based on palynological proxies and relative-age dating techniques. This study presents 29 cosmogenic 36Cl exposure ages of deglaciated bedrock surfaces and moraine deposits from Marion Island. In addition, a comprehensive glacial-geomorphological map, which in conjunction with exposure ages provide improved temporal and spatial constraints for the island’s glacial history. Results show that the ice reached a local Last Glacial Maximum before 56 ka ago and retreated, with minor stillstands, until ~17 ka. This early deglaciation left island surfaces below 850 m a.s.l. ice-free after ~19 ka, and any subsequent advances during the Late Glacial or Holocene cooling periods would have been restricted to the interior. This glacial chronology is similar to that of some other sub-Antarctic Islands (e.g. the Kerguelen archipelago, Auckland and Campbell islands, and possibly South Georgia) and a number of other Southern Hemisphere glaciers (e.g. in Patagonia and New Zealand) and adds to evidence that suggest the Southern Hemisphere was in a glacial maximum earlier than the global LGM. A combination of climatic drivers such as declining temperatures, a northward migration of oceanic fronts and the Southern Hemisphere Westerly Winds (causing precipitation changes), as well as the physiography of Marion Island, created optimal conditions for glacier growth during Marine Isotope Stage 4 (MIS 4; ~65 ka ago) instead of the global LGM in MIS 2 (~18 ka). These findings redefine the glacial history of Marion Island, and have implications for future investigations on post-glacial landscape development and ecological succession.
- Full Text:
- Date Issued: 2020
Understanding the links between smallholder farmers and retailers of meat and vegetables in Mthatha, Mqanduli, Port St Johns and Tsolo, Eastern Cape, South Africa
- Authors: Qaula, Nyaniso
- Date: 2020
- Subjects: Farms, Small
- Language: English
- Type: Thesis , Masters , M Agric
- Identifier: http://hdl.handle.net/10353/18823 , vital:42811
- Description: It is commonly accepted that one of the challenges faced by smallholder farmers is lack of ‘access to markets’. This is especially so against the backdrop of the supermarket revolution, which is widely understood to give advantage to large-scale farmers at the expense of smallholder farmers. Given that supermarkets are now well established even within South Africa’s former homelands, it would seem that even smallholders based in these areas are at a disadvantage. The purpose of this study is to delve deeply into the market access of smallholder farmers, and to do so specifically across a large area of the former Transkei where supermarkets are well established and where there are also a range of other types of retailers. The study seeks to understand the links between smallholder farmers and diverse kinds of food retailers of meat and vegetables in and around the towns of Mthatha, Mqanduli, Port St Johns and Tsolo in the Eastern Cape Province, South Africa. For each of these sites, the study estimates the share of purchased fresh vegetables and meat that ultimately originates from smallholder farmers within the former Transkei, as opposed to large-scale farmers further afield. The findings suggest that smallholder farmers account for about 24% to 40% of fresh vegetables, and 3% to 13% of meat. The difference between vegetables and meat seems to relate to the fact that smallholder farmers account for a reasonably large share of the fresh vegetables sold by at least some supermarkets, whereas smallholder livestock farmers are largely unable to sell to abattoirs, whether because of the standards imposed by these abattoirs (including the one in Mthatha), or because of the cost of transport. The differences between sites appear to be a function of several factors, including differential market size and resource endowments. The study further sought to identify the advantages and disadvantages that the different types of retailers experience in procuring from smallholder farmers, and also identify the advantages and disadvantages that smallholder farmers experience in supplying different types of retailers. The advantage of working with smallholder farmers is that smallholder farmers can even deliver on Sundays, unlike other suppliers that refuse to work during weekends. The disadvantage is that smallholder farmers are not producing consistently therefore it is hard to rely on smallholder farmers for supply of produce. The advantage that smallholder farmers experience in supplying different types of retailers is that they get their cash right away after delivering the produce. The challenge that smallholder farmers experience when supplying food retailers is that some of the supermarkets will see the sample and order large quantity, however on the day of delivery they will complain and say it is not the good quality so the farmers must reduce the selling price. The study suggests the strategy that could be used by farmers to access the market, which is to enhance knowledge of market skills and negotiation skills.
- Full Text:
- Date Issued: 2020
- Authors: Qaula, Nyaniso
- Date: 2020
- Subjects: Farms, Small
- Language: English
- Type: Thesis , Masters , M Agric
- Identifier: http://hdl.handle.net/10353/18823 , vital:42811
- Description: It is commonly accepted that one of the challenges faced by smallholder farmers is lack of ‘access to markets’. This is especially so against the backdrop of the supermarket revolution, which is widely understood to give advantage to large-scale farmers at the expense of smallholder farmers. Given that supermarkets are now well established even within South Africa’s former homelands, it would seem that even smallholders based in these areas are at a disadvantage. The purpose of this study is to delve deeply into the market access of smallholder farmers, and to do so specifically across a large area of the former Transkei where supermarkets are well established and where there are also a range of other types of retailers. The study seeks to understand the links between smallholder farmers and diverse kinds of food retailers of meat and vegetables in and around the towns of Mthatha, Mqanduli, Port St Johns and Tsolo in the Eastern Cape Province, South Africa. For each of these sites, the study estimates the share of purchased fresh vegetables and meat that ultimately originates from smallholder farmers within the former Transkei, as opposed to large-scale farmers further afield. The findings suggest that smallholder farmers account for about 24% to 40% of fresh vegetables, and 3% to 13% of meat. The difference between vegetables and meat seems to relate to the fact that smallholder farmers account for a reasonably large share of the fresh vegetables sold by at least some supermarkets, whereas smallholder livestock farmers are largely unable to sell to abattoirs, whether because of the standards imposed by these abattoirs (including the one in Mthatha), or because of the cost of transport. The differences between sites appear to be a function of several factors, including differential market size and resource endowments. The study further sought to identify the advantages and disadvantages that the different types of retailers experience in procuring from smallholder farmers, and also identify the advantages and disadvantages that smallholder farmers experience in supplying different types of retailers. The advantage of working with smallholder farmers is that smallholder farmers can even deliver on Sundays, unlike other suppliers that refuse to work during weekends. The disadvantage is that smallholder farmers are not producing consistently therefore it is hard to rely on smallholder farmers for supply of produce. The advantage that smallholder farmers experience in supplying different types of retailers is that they get their cash right away after delivering the produce. The challenge that smallholder farmers experience when supplying food retailers is that some of the supermarkets will see the sample and order large quantity, however on the day of delivery they will complain and say it is not the good quality so the farmers must reduce the selling price. The study suggests the strategy that could be used by farmers to access the market, which is to enhance knowledge of market skills and negotiation skills.
- Full Text:
- Date Issued: 2020