Comparative analysis of characteristics of the various sugarcane bagasse types in terms of gasification
- Authors: Kula, Mpumezo
- Date: 2016
- Subjects: Bagasse Sugarcane -- Breeding Coal gasification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13392 , vital:39656
- Description: The insight that the fossil fuel reserves are limited, together with concerns over security of supply (i.e. the oil crises), initiated the first raise of interest in biomass and all other renewable energy forms. However, the concern grew that global warming and the resulting climate change were enhanced by carbon dioxide (CO2) emissions resulting from fossil fuel consumption. Meanwhile, biomass energy is thought to account for 14–15percent of total world energy consumption. Hence, the exploitation and utilization of biomass energy are effective and necessary for relieving the pressures caused by environmental pollution and fossil fuel shortage (Lv et al., 2010). Recently, extensive research aimed at converting biomass to useful energy have been carried out, especially pyrolysis and gasification, which are particularly suitable for the effective and efficient utilization of biomass. Sugarcane bagasse is the main byproduct of sugarcane mill, ready available at the production site so that it may be a suitable raw material for the production of biofuels, chemicals, and electricity. Among the methods that have been previously studied, is this particular study we explore thermochemical process, gasification. The properties of sugarcane bagasse relevant to gasification are briefly reviewed. The compositions of the bagasse as a fuel are variable, especially with respect to inorganic constituents important to the critical problems of sintering, fouling and slagging. Alkali and alkaline earth metals, in combination with other fuel elements such as silica and sulfur, are responsible for many undesirable reactions in a gasifier system. The three sugarcane bagasse types namely washed, unwashed and the depithed sugarcane bagasse were subjected in different types of characterization to review and compare their characteristics for gasification. Ultimate analysis was used to determine the elemental compositions and this was helpful in estimating the energy input of the materials. Elemental compositions were determined with the CHNS analyzer which gave the percent compositions of each fuel in terms of Carbon, Hydrogen, Nitrogen, Sulphur as well as Oxygen (by difference) and the SEM/EDX which gave the elemental composition of the materials as can be viewed from the EDX. The proximate analysis which is the physical characterization of the materials was carried out to preview the behavior of the sugarcane bagasse when subjected into high temperatures as the gasification process uses very high temperatures. These were determined by the TGA and the volatile matter content; fixed carbon content, moisture content and ash content were extrapolated from the resulting thermogram. SEM images for surface structures of the bagasse and FTIR for the structural functionality and bonding structures. The characterization of the bagasse was conducted to compare their gasification properties.
- Full Text:
- Date Issued: 2016
- Authors: Kula, Mpumezo
- Date: 2016
- Subjects: Bagasse Sugarcane -- Breeding Coal gasification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13392 , vital:39656
- Description: The insight that the fossil fuel reserves are limited, together with concerns over security of supply (i.e. the oil crises), initiated the first raise of interest in biomass and all other renewable energy forms. However, the concern grew that global warming and the resulting climate change were enhanced by carbon dioxide (CO2) emissions resulting from fossil fuel consumption. Meanwhile, biomass energy is thought to account for 14–15percent of total world energy consumption. Hence, the exploitation and utilization of biomass energy are effective and necessary for relieving the pressures caused by environmental pollution and fossil fuel shortage (Lv et al., 2010). Recently, extensive research aimed at converting biomass to useful energy have been carried out, especially pyrolysis and gasification, which are particularly suitable for the effective and efficient utilization of biomass. Sugarcane bagasse is the main byproduct of sugarcane mill, ready available at the production site so that it may be a suitable raw material for the production of biofuels, chemicals, and electricity. Among the methods that have been previously studied, is this particular study we explore thermochemical process, gasification. The properties of sugarcane bagasse relevant to gasification are briefly reviewed. The compositions of the bagasse as a fuel are variable, especially with respect to inorganic constituents important to the critical problems of sintering, fouling and slagging. Alkali and alkaline earth metals, in combination with other fuel elements such as silica and sulfur, are responsible for many undesirable reactions in a gasifier system. The three sugarcane bagasse types namely washed, unwashed and the depithed sugarcane bagasse were subjected in different types of characterization to review and compare their characteristics for gasification. Ultimate analysis was used to determine the elemental compositions and this was helpful in estimating the energy input of the materials. Elemental compositions were determined with the CHNS analyzer which gave the percent compositions of each fuel in terms of Carbon, Hydrogen, Nitrogen, Sulphur as well as Oxygen (by difference) and the SEM/EDX which gave the elemental composition of the materials as can be viewed from the EDX. The proximate analysis which is the physical characterization of the materials was carried out to preview the behavior of the sugarcane bagasse when subjected into high temperatures as the gasification process uses very high temperatures. These were determined by the TGA and the volatile matter content; fixed carbon content, moisture content and ash content were extrapolated from the resulting thermogram. SEM images for surface structures of the bagasse and FTIR for the structural functionality and bonding structures. The characterization of the bagasse was conducted to compare their gasification properties.
- Full Text:
- Date Issued: 2016
Characterization of the heat source of thermal aquifers within the Soutpansberg Basin in the Limpopo Province, South Africa: Evidence from geophysical and geological investigations
- Authors: Nyabeze, Peter Kushara
- Date: 2019
- Subjects: Basins (Geology) -- Analysis Geology, Structural -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD (Geology)
- Identifier: http://hdl.handle.net/10353/15167 , vital:40192
- Description: The research was conducted to contribute towards the knowledge base on the potential for geothermal energy in the Soutpansberg Basin, located in the Limpopo Province of South Africa. The focus area was Siloam, an area that hosts a hottest spring with the highest recorded temperature of 67.5°C. The research involved visits to the Soutpansberg Basin, water sampling, carrying out ground geophysical surveys, and high-level processing of airborne magnetic data to determine depths and temperatures of magnetic sources. The water samples from the hot springs were found to be enriched in sodium, bicarbonate and chlorine with very low concentrations of other element species. The chemical composition of the spring water indicated a source chemistry comprising of the Na-ClHCO3 water assemblage that is a typical signature for deep circulating groundwater of meteoric origin. The circulation depth was inferred to be 2.0 km. The increased resolution of the ground magnetic, electrical resistivity tomography, and electromagnetic conductivity methods data made it possible to delineate subsurface structures at the spring such as dykes, sills, faults and fractures from generated depth models. Modelling of ground magnetic data showed that the Siloam hot spring occurred between two interpreted north dipping dykes approximately 150 m apart. The minimum depth extent of the dykes was interpreted to be 650 m. The magnetic susceptibility values determined from rock measurements and modelling of magnetic data indicated the presence of volcanic and metamorphic rocks. Electromagnetic profiling data showed that there were three main high conductivity zones in the study area with values above 100 mS/m; A central zone associated with the spring; A zone to the south of the spring and a north zone associated with the Siloam Fault. Ground geophysics survey results confirmed the existence of the Siloam Fault. Two artesian boreholes with water warmer than 40 °C were identified to the south of the Siloam hot spring. Both electromagnetic conductivity and electrical resistivity tomography surveys delineated lateral and vertical variation in the bedrock to depths of 40 m to 60 m. Water bearing structures that could be faults, or fractures were identified. Layering due to weathering and water content was found to be in the depth range of 20 m to 40 m. The depths of the potential heat sources were computed from the radially averaged power spectrum of airborne magnetic data for square blocks with side dimensions L of 51 km, 103 km, and 129 km. Spectral analysis based approaches namely Centroid method, Spectral peak method, and the Fractal based approach were used for computing depth and temperatures to heat sources. Airborne magnetic data sets with larger window sizes were preferred for depth computations, as they preserved spectral signatures of deeper sources and reduced the contribution of shallower sources. The size of the data windows did not have a marked effect of depth and temperature values. Shallower magnetic sources depths of approximately 2.0 km were delineated using the Euler deconvolution method. An anticlinal feature at depths of 2.0 to 4.5 km was 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper delineated in the central part of the basin. Spectral analysis results indicated that the depth to the top of magnetic sources was at 3.5 km to 6.2 km; the centroid of the basement at 7.92 km to 13.41 km, and the basal below 11.09 km and 14.08 km. The lower end depth spectrum was determined from application of the Centroid method with the deeper being results from the Fractal based approach. The Spectral peak method was useful for determining the depth to the top of magnetic sources. The temperature of the top of magnetic sources and basement centroid were computed to be in the range 234.00 °C to 281.34 °C. Magnetic source depths and basal temperatures that were in the Curie point range within which rocks lose magnetism due to heat were determined, using a computation approach that utilised fractal parameters, to be 21.39 km and 577.42 °C, respectively. Increasing the value of the fractal parameter β from 0 to 4, had an effect of retaining deeper depths and higher temperatures. The fractal parameter β range of 3 to 4 that gave the Curie point parameters indicated basal rock types with an igneous predisposition. The research highlighted evidence for the existence of the Soutpansberg Basin Geothermal Field (SBGF). The area around Siloam is a potential target for drilling exploration geothermal energy boreholes based on the occurrence of hot springs, shallow heat source depths, anticlinal structure, high formation temperatures, deep circulating water and the achieved Curie point temperature.
- Full Text:
- Date Issued: 2019
- Authors: Nyabeze, Peter Kushara
- Date: 2019
- Subjects: Basins (Geology) -- Analysis Geology, Structural -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD (Geology)
- Identifier: http://hdl.handle.net/10353/15167 , vital:40192
- Description: The research was conducted to contribute towards the knowledge base on the potential for geothermal energy in the Soutpansberg Basin, located in the Limpopo Province of South Africa. The focus area was Siloam, an area that hosts a hottest spring with the highest recorded temperature of 67.5°C. The research involved visits to the Soutpansberg Basin, water sampling, carrying out ground geophysical surveys, and high-level processing of airborne magnetic data to determine depths and temperatures of magnetic sources. The water samples from the hot springs were found to be enriched in sodium, bicarbonate and chlorine with very low concentrations of other element species. The chemical composition of the spring water indicated a source chemistry comprising of the Na-ClHCO3 water assemblage that is a typical signature for deep circulating groundwater of meteoric origin. The circulation depth was inferred to be 2.0 km. The increased resolution of the ground magnetic, electrical resistivity tomography, and electromagnetic conductivity methods data made it possible to delineate subsurface structures at the spring such as dykes, sills, faults and fractures from generated depth models. Modelling of ground magnetic data showed that the Siloam hot spring occurred between two interpreted north dipping dykes approximately 150 m apart. The minimum depth extent of the dykes was interpreted to be 650 m. The magnetic susceptibility values determined from rock measurements and modelling of magnetic data indicated the presence of volcanic and metamorphic rocks. Electromagnetic profiling data showed that there were three main high conductivity zones in the study area with values above 100 mS/m; A central zone associated with the spring; A zone to the south of the spring and a north zone associated with the Siloam Fault. Ground geophysics survey results confirmed the existence of the Siloam Fault. Two artesian boreholes with water warmer than 40 °C were identified to the south of the Siloam hot spring. Both electromagnetic conductivity and electrical resistivity tomography surveys delineated lateral and vertical variation in the bedrock to depths of 40 m to 60 m. Water bearing structures that could be faults, or fractures were identified. Layering due to weathering and water content was found to be in the depth range of 20 m to 40 m. The depths of the potential heat sources were computed from the radially averaged power spectrum of airborne magnetic data for square blocks with side dimensions L of 51 km, 103 km, and 129 km. Spectral analysis based approaches namely Centroid method, Spectral peak method, and the Fractal based approach were used for computing depth and temperatures to heat sources. Airborne magnetic data sets with larger window sizes were preferred for depth computations, as they preserved spectral signatures of deeper sources and reduced the contribution of shallower sources. The size of the data windows did not have a marked effect of depth and temperature values. Shallower magnetic sources depths of approximately 2.0 km were delineated using the Euler deconvolution method. An anticlinal feature at depths of 2.0 to 4.5 km was 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper delineated in the central part of the basin. Spectral analysis results indicated that the depth to the top of magnetic sources was at 3.5 km to 6.2 km; the centroid of the basement at 7.92 km to 13.41 km, and the basal below 11.09 km and 14.08 km. The lower end depth spectrum was determined from application of the Centroid method with the deeper being results from the Fractal based approach. The Spectral peak method was useful for determining the depth to the top of magnetic sources. The temperature of the top of magnetic sources and basement centroid were computed to be in the range 234.00 °C to 281.34 °C. Magnetic source depths and basal temperatures that were in the Curie point range within which rocks lose magnetism due to heat were determined, using a computation approach that utilised fractal parameters, to be 21.39 km and 577.42 °C, respectively. Increasing the value of the fractal parameter β from 0 to 4, had an effect of retaining deeper depths and higher temperatures. The fractal parameter β range of 3 to 4 that gave the Curie point parameters indicated basal rock types with an igneous predisposition. The research highlighted evidence for the existence of the Soutpansberg Basin Geothermal Field (SBGF). The area around Siloam is a potential target for drilling exploration geothermal energy boreholes based on the occurrence of hot springs, shallow heat source depths, anticlinal structure, high formation temperatures, deep circulating water and the achieved Curie point temperature.
- Full Text:
- Date Issued: 2019
Examining the nature of entrepreneurship within the towns and rural areas of Sakhisizwe Local Municipality, Eastern Cape
- Authors: Maliwa, Noluvuyo
- Date: 2022-11
- Subjects: Entrepreneurship , Developing countries--Economic conditions , Small business
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27555 , vital:69315
- Description: Entrepreneurship plays an important role in societies around the world because it supports economic growth and creates job opportunities. This study investigated the nature of entrepreneurship in three distinct parts of Sakhisizwe Local Municipality, including a town within Sakhisizwe’s former homeland area, rural communities within its former homeland area, and a town within an area characterised by large-scale commercial farms. The study sought to establish the share of adults in the different parts of the municipality involved in entrepreneurship, to identify factors that contribute to the decision to become an entrepreneur, and to examine strategies pursued by, and challenges experienced, different types of entrepreneurs. The study involved a random sample of 362 respondents and both quantitative and qualitative data analysis. Among the main findings is that the proportion of adults involved in enterprise in Sakhisizwe is higher than found by other studies for South Africa as a whole, but is especially high for those living in the town in the former homeland area. While those residing in rural communities also engage in enterprise, they are generally compelled to practice their enterprises in town, thus have the disadvantage of needing frequent transport. While residing in the town in the commercial farming area is not disadvantageous in the same way, the challenge is that the town itself is able to support relatively few entrepreneurs due to fewer people coming to town for their shopping. , Thesis (MSci) -- Faculty of Science and Agricultures, 2022
- Full Text:
- Date Issued: 2022-11
- Authors: Maliwa, Noluvuyo
- Date: 2022-11
- Subjects: Entrepreneurship , Developing countries--Economic conditions , Small business
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27555 , vital:69315
- Description: Entrepreneurship plays an important role in societies around the world because it supports economic growth and creates job opportunities. This study investigated the nature of entrepreneurship in three distinct parts of Sakhisizwe Local Municipality, including a town within Sakhisizwe’s former homeland area, rural communities within its former homeland area, and a town within an area characterised by large-scale commercial farms. The study sought to establish the share of adults in the different parts of the municipality involved in entrepreneurship, to identify factors that contribute to the decision to become an entrepreneur, and to examine strategies pursued by, and challenges experienced, different types of entrepreneurs. The study involved a random sample of 362 respondents and both quantitative and qualitative data analysis. Among the main findings is that the proportion of adults involved in enterprise in Sakhisizwe is higher than found by other studies for South Africa as a whole, but is especially high for those living in the town in the former homeland area. While those residing in rural communities also engage in enterprise, they are generally compelled to practice their enterprises in town, thus have the disadvantage of needing frequent transport. While residing in the town in the commercial farming area is not disadvantageous in the same way, the challenge is that the town itself is able to support relatively few entrepreneurs due to fewer people coming to town for their shopping. , Thesis (MSci) -- Faculty of Science and Agricultures, 2022
- Full Text:
- Date Issued: 2022-11
Economic change in town and countryside in the former Transkei : land use, livelihoods and market linkages in Ngcobo, Eastern Cape, South Africa
- Authors: Nikelo, Nqaba Benedictor
- Date: 2018
- Subjects: Homelands (South Africa) Homelands (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , Agricultural Economics
- Identifier: http://hdl.handle.net/10353/10768 , vital:35757
- Description: In 1913 in South Africa the natives of land act during apartheid resulted to the separation of South Africa. South Africa was divided into two areas where they were black and white areas. This act had a rule that said the black people can only move out of their lands only if employed as labourers by the whites. The white population was one-fifth of the population and was given 92.5 percent of the land while the rest of the population were blacks and they were restricted to stay on the 7.5 percent of land. In the Eastern Cape, two homelands were created: the Transkei (in 1951) and the Ciskei (in 1961). In 1963 the Transkei became the first homeland to be granted the status of 'self-governing territory within the Republic of South Africa’, with the Ciskei following suit in 1972. The apartheid policies caused economic failure and corruption because very little economic and infrastructural development took place in the homelands. According to the ‘legacy perspective’: the former homelands are historically-determined structural poverty traps. The objective of the study is to describe the extent and change of economic function/role of Ngcobo town and linkages with its surrounding villages. Availability or convenient sampling and random sampling techniques were used to collect primary data from farmers and surrounding villages. Descriptive statistics was used to profile farmers as well as the participants in the surrounding villages. Descriptive statistics was used to describe the change in the economy of Ngcobo town and the change in the economy of the surrounding rural areas. Households in the former homelands devote a large share of their total expenditure to food and beverages, and yet it would appear that a relatively small share of this food originates from these same rural areas. The point of departure of this report is the observation that rural areas are diverse, whereby some areas within the former homeland areas in particular exhibit signs of dynamism which are not understandable in terms of the ‘legacy perspective’.
- Full Text:
- Date Issued: 2018
- Authors: Nikelo, Nqaba Benedictor
- Date: 2018
- Subjects: Homelands (South Africa) Homelands (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , Agricultural Economics
- Identifier: http://hdl.handle.net/10353/10768 , vital:35757
- Description: In 1913 in South Africa the natives of land act during apartheid resulted to the separation of South Africa. South Africa was divided into two areas where they were black and white areas. This act had a rule that said the black people can only move out of their lands only if employed as labourers by the whites. The white population was one-fifth of the population and was given 92.5 percent of the land while the rest of the population were blacks and they were restricted to stay on the 7.5 percent of land. In the Eastern Cape, two homelands were created: the Transkei (in 1951) and the Ciskei (in 1961). In 1963 the Transkei became the first homeland to be granted the status of 'self-governing territory within the Republic of South Africa’, with the Ciskei following suit in 1972. The apartheid policies caused economic failure and corruption because very little economic and infrastructural development took place in the homelands. According to the ‘legacy perspective’: the former homelands are historically-determined structural poverty traps. The objective of the study is to describe the extent and change of economic function/role of Ngcobo town and linkages with its surrounding villages. Availability or convenient sampling and random sampling techniques were used to collect primary data from farmers and surrounding villages. Descriptive statistics was used to profile farmers as well as the participants in the surrounding villages. Descriptive statistics was used to describe the change in the economy of Ngcobo town and the change in the economy of the surrounding rural areas. Households in the former homelands devote a large share of their total expenditure to food and beverages, and yet it would appear that a relatively small share of this food originates from these same rural areas. The point of departure of this report is the observation that rural areas are diverse, whereby some areas within the former homeland areas in particular exhibit signs of dynamism which are not understandable in terms of the ‘legacy perspective’.
- Full Text:
- Date Issued: 2018
Effects of different grazing system on forage production and seasonal parasite loads in beef cattle
- Rapiya, Monde, Mupangwa, John
- Authors: Rapiya, Monde , Mupangwa, John
- Date: 2017
- Subjects: Grazing Forage plants Forage
- Language: English
- Type: Thesis , Masters , (MSc) Pasture Science
- Identifier: http://hdl.handle.net/10353/9253 , vital:34314
- Description: The objectives of the study were to determine the effects of grazing systems on rangeland biomass yield and nutritional composition, tick and faecal egg counts in beef cattle across seasons. The study was conducted at Merino Walk farm located in Matatiele in the northern part of the Eastern Cape Province, South Africa. The farm was divided into three experimental plots of 3.5 ha each. Thereafter, three grazing treatments namely, Holistic Planned Grazing (HPG paddocks), Four-camp rotation (FCR) and continuous grazing (CG), were randomly allocated to the experimental plots. In the FCR system, the 3.5ha was subdivided into four 0.875-ha paddocks, while the HPG system was subdivided into ninety (90) 0.039-ha paddocks. Common forages were hand-clipped at a grazing height of (5cm) in the wet and dry season from six quadrats (0.25m2) placed in each plot and evaluated for biomass yield and nutritional composition. Thirty (30) steers of the same age 12-month old of similar weight were randomly allocated to three grazing treatments (10/treatments). Tick counts were recorded for each steer in the hot-wet, hot-dry, post-rainy and cold dry seasons. Faecal samples were collected per-rectum every in four seasons and analysed for faecal egg counts using the modified McMaster method. The data were analysed using PROC Generalized Linear Model of SAS (2012) to determine the effects of grazing system on rangeland biomass yield, nutritional composition, tick and faecal egg counts. The common grass species in all grazing system across season were Cynodon dactylon, Eragrostis chloromelus, Eragrostis plana, Fescuta and Themeda triandra. The FCR system in the wet season had significant the lowest (P<0.05) biomass yield of 62605,33kg/ha compared to other treatments which had mean values of 62625,97 and 62625,89kg/ha for HPG and CG, respectively (P<0.05). Crude protein content was higher (P<0.05) in HPG (9.41percentCP) and FCR (9.22percentCP) systems in the wet season compared to CG across seasons. Forage from HPG system, irrespective of season had significant lower starch content than other treatments (P<0.05). Forage from HPG system, irrespective of season had the lower (P<0.05) starch content than other treatments. Regardless of season, CG had higher (P<0.05) NDF (72.51 and 72.50) and ADF (41.93 and 40.45) contents than FCR and HPG treatments. Overall, HPG system regardless of season and FCR in the wet season had higher (P<0.05) in vitro digestibility at 24 and 48hrs (0.38 and 0.66) incubation periods. The tick species identified were Rhipicephalus evertsi evertsi, Rhipicephalus (Boophilus) decoloratus, Hyalomma spp and Amblyomma hebreaum with respective prevalence’s of 32percent, 29percent, 20percent and 19percent. Unidentified roundworms (URW), had the highest faecal egg counts (81.2percent) followed by Coccidia (16.4percent), Nematodirus (1.2percent) and Strongyles (1.2percent). Overall, steers on the CG system during hot-wet season had the highest individual and total tick counts (17.0) whilst those on FCR during the cold-dry season had the lowest counts (6.0). Holistic Planned Grazing had the lowest worm egg counts regardless of season, while CG had the highest counts in the hot wet season (P<0.05). The findings showed that relative to other treatments, the HPG system in wet season had a higher biomass yield and better nutritional composition (high CP, low fibre and high digestibility) with low forage production and quality under CG system during the cold-dry season. Whilst, CG during hot-wet season had the highest total tick and worm egg counts and least counts under HPG during the cold-dry. Based on relatively higher forage production and low parasite loads, HPG could be a better grazing management system than CG and FCR, especially in the wet season. It may be important to evaluate the effect of HPG on animal production, product quality and profitability prior to recommending it for use by farmers.
- Full Text:
- Date Issued: 2017
- Authors: Rapiya, Monde , Mupangwa, John
- Date: 2017
- Subjects: Grazing Forage plants Forage
- Language: English
- Type: Thesis , Masters , (MSc) Pasture Science
- Identifier: http://hdl.handle.net/10353/9253 , vital:34314
- Description: The objectives of the study were to determine the effects of grazing systems on rangeland biomass yield and nutritional composition, tick and faecal egg counts in beef cattle across seasons. The study was conducted at Merino Walk farm located in Matatiele in the northern part of the Eastern Cape Province, South Africa. The farm was divided into three experimental plots of 3.5 ha each. Thereafter, three grazing treatments namely, Holistic Planned Grazing (HPG paddocks), Four-camp rotation (FCR) and continuous grazing (CG), were randomly allocated to the experimental plots. In the FCR system, the 3.5ha was subdivided into four 0.875-ha paddocks, while the HPG system was subdivided into ninety (90) 0.039-ha paddocks. Common forages were hand-clipped at a grazing height of (5cm) in the wet and dry season from six quadrats (0.25m2) placed in each plot and evaluated for biomass yield and nutritional composition. Thirty (30) steers of the same age 12-month old of similar weight were randomly allocated to three grazing treatments (10/treatments). Tick counts were recorded for each steer in the hot-wet, hot-dry, post-rainy and cold dry seasons. Faecal samples were collected per-rectum every in four seasons and analysed for faecal egg counts using the modified McMaster method. The data were analysed using PROC Generalized Linear Model of SAS (2012) to determine the effects of grazing system on rangeland biomass yield, nutritional composition, tick and faecal egg counts. The common grass species in all grazing system across season were Cynodon dactylon, Eragrostis chloromelus, Eragrostis plana, Fescuta and Themeda triandra. The FCR system in the wet season had significant the lowest (P<0.05) biomass yield of 62605,33kg/ha compared to other treatments which had mean values of 62625,97 and 62625,89kg/ha for HPG and CG, respectively (P<0.05). Crude protein content was higher (P<0.05) in HPG (9.41percentCP) and FCR (9.22percentCP) systems in the wet season compared to CG across seasons. Forage from HPG system, irrespective of season had significant lower starch content than other treatments (P<0.05). Forage from HPG system, irrespective of season had the lower (P<0.05) starch content than other treatments. Regardless of season, CG had higher (P<0.05) NDF (72.51 and 72.50) and ADF (41.93 and 40.45) contents than FCR and HPG treatments. Overall, HPG system regardless of season and FCR in the wet season had higher (P<0.05) in vitro digestibility at 24 and 48hrs (0.38 and 0.66) incubation periods. The tick species identified were Rhipicephalus evertsi evertsi, Rhipicephalus (Boophilus) decoloratus, Hyalomma spp and Amblyomma hebreaum with respective prevalence’s of 32percent, 29percent, 20percent and 19percent. Unidentified roundworms (URW), had the highest faecal egg counts (81.2percent) followed by Coccidia (16.4percent), Nematodirus (1.2percent) and Strongyles (1.2percent). Overall, steers on the CG system during hot-wet season had the highest individual and total tick counts (17.0) whilst those on FCR during the cold-dry season had the lowest counts (6.0). Holistic Planned Grazing had the lowest worm egg counts regardless of season, while CG had the highest counts in the hot wet season (P<0.05). The findings showed that relative to other treatments, the HPG system in wet season had a higher biomass yield and better nutritional composition (high CP, low fibre and high digestibility) with low forage production and quality under CG system during the cold-dry season. Whilst, CG during hot-wet season had the highest total tick and worm egg counts and least counts under HPG during the cold-dry. Based on relatively higher forage production and low parasite loads, HPG could be a better grazing management system than CG and FCR, especially in the wet season. It may be important to evaluate the effect of HPG on animal production, product quality and profitability prior to recommending it for use by farmers.
- Full Text:
- Date Issued: 2017
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
Effects of production systems and canola meal supplementation on carcass and meat quality characteristics of spent laying hens
- Authors: Semwogerere, Farouk
- Date: 2018
- Subjects: Broilers (Chickens) -- Feeding and feeds Chickens -- Feeding and feeds Chicken industry -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9242 , vital:34309
- Description: This study evaluated the carcass and meat quality traits of spent laying hens as influenced by production systems (conventional cages and free range) and the inclusion/exclusion of canola meal in their diets. A total of 30 free range and 60 battery cage reared Lohmann Brown-Elite spent laying hens were obtained from a commercial egg producer. The 30 free range hens (53 weeks of age) and 30 of the caged hens (40 weeks of age) were fed a conventional diet, while the remaining 30 caged hens (48 weeks of age) were fed a diet supplemented with canola meal (20 percent). Carcass, portion and organ weights were determined. Physical attributes and proximate composition were analyzed for, with additional fatty acids and sensory profiles being determined for the effects of canola meal inclusion in the diet. Caged hens had heavier (P ≤ 0.05) warm and cold carcasses, thigh, wing and feet compared to free range hens. The percentages of the breast (26.1 ± 0.51 vs. 28.3 ± 0.28), drum, breast bones, breast thaw and cooking losses and thigh cooking loss were lower (P ≤ 0.05) for caged hens than for free range hens. Free range hens had heavier (P ≤ 0.05) gizzards (33.9 ± 1.04 vs. 30.5 ± 0.73) and bones and a lower (P ≤ 0.05) breast meat percentage (47.3 ± 0.94 vs. 51.7 ± 1.35). Meat redness (a*) (0.54 ± 0.222 vs. 1.40 ± 0.135) and hue angle value, skin redness (a*), breast and thigh, Warner-Bratzler shear force (WBSF) values (breast: 12.37 ± 0.411 vs. 17.10 ± 0.751, thigh: 29.68 ± 0.306 vs. 39.75 ± 0.826), breast moisture and thigh ash content were lower (P ≤ 0.05) for caged hens than free range hens. Caged hens had higher (P ≤ 0.05) thigh thaw loss and breast ash content than free range hens. Canola-fed hens had higher (P ≤ 0.05) drum percentages, breast bone weights and percentages, with lower (P ≤ 0.05) thigh and breast meat percentages. Canola-fed hens had lower (P ≤ 0.05) thaw losses, skin yellowness (b*) and Chroma values, breast fat content with higher cooking losses, skin redness (a*) and hue angle value, as well as breast WBSF (12.37 ± 0.411 vs. 15.43 ± 0.600). Palmitic acid, stearic acid, heneicosanoic acid acid, palmitoleic acid, saturated fatty acids (SFA) (34.0 ± 0.56 vs. 38.7 ± 0.71), n-6:n-3 polyunsaturated fatty acids (PUFA) ratio (5.5 ± 0.13 vs. 7.2 ± 0.28), atherogenic index (IA), thrombogenic index (IT), delta-5 desaturase (D5D, elongase index and thiosterase index were lower (P ≤ 0.05) for canola-fed hen breast meat. Breast meat from conventionally fed hens had lower (P ≤ 0.05) myristic acid, lignoceric acid, nervonic acid, alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), PUFA:SFA ratio (0.7 ± 0.05 vs. 0.9 ± 0.02), n-3 PUFA (3.4 ± 0.31 vs. 5.1 ± 0.17), hypocholesterolemic:Hypercholesterolaemic (h/H), stearoyl-CoA desaturase 16 (SCD16) and stearoyl-CoA desaturase 18 (SCD18). The breast meat from conventionally fed hens had lower (P ≤ 0.05) metallic flavor than that from canola-fed hens. Strong positive correlations were observed for overall aroma with chicken (r = 0.965, P < 0.001) and brothy aroma (r = 0.827, P < 0.001); overall aroma with overall flavor (r = 0.680, P < 0.001), chicken flavor (r = 0.668, P < 0.001) and brothy flavor (r = 0.548, P = 0.006); initial juiciness with sustained juiciness (r = 0.771, P < 0.001) and tenderness (r = 0.537, P = 0.007); sustained juiciness with tenderness (r = 0.790, P < 0.001) and chewiness with residue (r = 0.783, P < 0.001). Whilst strong negative correlations were observed for: sustained juiciness with chewiness (r = -0.655, P = 0.001) and residue (r = 0.783, P < 0.001) and for tenderness with chewiness (r = 0.845, P < 0.001) and residue (r = -0.855, P < 0.001). Results of this study highlight that a free range production system when compared to a conventional cage system increased undesirable carcass and physical meat traits of spent laying hens. On the other hand, canola meal inclusion incorporates beneficial health aspects without affecting the sensory profile of meat derived from spent laying hens, both groups of hens being reared in battery cage system. Spent laying hen breasts can be consumed as a functional food (especially canolafed) since the fat content and composition was observed to be close to that which is recommended for a healthy diet.
- Full Text:
- Date Issued: 2018
- Authors: Semwogerere, Farouk
- Date: 2018
- Subjects: Broilers (Chickens) -- Feeding and feeds Chickens -- Feeding and feeds Chicken industry -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9242 , vital:34309
- Description: This study evaluated the carcass and meat quality traits of spent laying hens as influenced by production systems (conventional cages and free range) and the inclusion/exclusion of canola meal in their diets. A total of 30 free range and 60 battery cage reared Lohmann Brown-Elite spent laying hens were obtained from a commercial egg producer. The 30 free range hens (53 weeks of age) and 30 of the caged hens (40 weeks of age) were fed a conventional diet, while the remaining 30 caged hens (48 weeks of age) were fed a diet supplemented with canola meal (20 percent). Carcass, portion and organ weights were determined. Physical attributes and proximate composition were analyzed for, with additional fatty acids and sensory profiles being determined for the effects of canola meal inclusion in the diet. Caged hens had heavier (P ≤ 0.05) warm and cold carcasses, thigh, wing and feet compared to free range hens. The percentages of the breast (26.1 ± 0.51 vs. 28.3 ± 0.28), drum, breast bones, breast thaw and cooking losses and thigh cooking loss were lower (P ≤ 0.05) for caged hens than for free range hens. Free range hens had heavier (P ≤ 0.05) gizzards (33.9 ± 1.04 vs. 30.5 ± 0.73) and bones and a lower (P ≤ 0.05) breast meat percentage (47.3 ± 0.94 vs. 51.7 ± 1.35). Meat redness (a*) (0.54 ± 0.222 vs. 1.40 ± 0.135) and hue angle value, skin redness (a*), breast and thigh, Warner-Bratzler shear force (WBSF) values (breast: 12.37 ± 0.411 vs. 17.10 ± 0.751, thigh: 29.68 ± 0.306 vs. 39.75 ± 0.826), breast moisture and thigh ash content were lower (P ≤ 0.05) for caged hens than free range hens. Caged hens had higher (P ≤ 0.05) thigh thaw loss and breast ash content than free range hens. Canola-fed hens had higher (P ≤ 0.05) drum percentages, breast bone weights and percentages, with lower (P ≤ 0.05) thigh and breast meat percentages. Canola-fed hens had lower (P ≤ 0.05) thaw losses, skin yellowness (b*) and Chroma values, breast fat content with higher cooking losses, skin redness (a*) and hue angle value, as well as breast WBSF (12.37 ± 0.411 vs. 15.43 ± 0.600). Palmitic acid, stearic acid, heneicosanoic acid acid, palmitoleic acid, saturated fatty acids (SFA) (34.0 ± 0.56 vs. 38.7 ± 0.71), n-6:n-3 polyunsaturated fatty acids (PUFA) ratio (5.5 ± 0.13 vs. 7.2 ± 0.28), atherogenic index (IA), thrombogenic index (IT), delta-5 desaturase (D5D, elongase index and thiosterase index were lower (P ≤ 0.05) for canola-fed hen breast meat. Breast meat from conventionally fed hens had lower (P ≤ 0.05) myristic acid, lignoceric acid, nervonic acid, alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), PUFA:SFA ratio (0.7 ± 0.05 vs. 0.9 ± 0.02), n-3 PUFA (3.4 ± 0.31 vs. 5.1 ± 0.17), hypocholesterolemic:Hypercholesterolaemic (h/H), stearoyl-CoA desaturase 16 (SCD16) and stearoyl-CoA desaturase 18 (SCD18). The breast meat from conventionally fed hens had lower (P ≤ 0.05) metallic flavor than that from canola-fed hens. Strong positive correlations were observed for overall aroma with chicken (r = 0.965, P < 0.001) and brothy aroma (r = 0.827, P < 0.001); overall aroma with overall flavor (r = 0.680, P < 0.001), chicken flavor (r = 0.668, P < 0.001) and brothy flavor (r = 0.548, P = 0.006); initial juiciness with sustained juiciness (r = 0.771, P < 0.001) and tenderness (r = 0.537, P = 0.007); sustained juiciness with tenderness (r = 0.790, P < 0.001) and chewiness with residue (r = 0.783, P < 0.001). Whilst strong negative correlations were observed for: sustained juiciness with chewiness (r = -0.655, P = 0.001) and residue (r = 0.783, P < 0.001) and for tenderness with chewiness (r = 0.845, P < 0.001) and residue (r = -0.855, P < 0.001). Results of this study highlight that a free range production system when compared to a conventional cage system increased undesirable carcass and physical meat traits of spent laying hens. On the other hand, canola meal inclusion incorporates beneficial health aspects without affecting the sensory profile of meat derived from spent laying hens, both groups of hens being reared in battery cage system. Spent laying hen breasts can be consumed as a functional food (especially canolafed) since the fat content and composition was observed to be close to that which is recommended for a healthy diet.
- Full Text:
- Date Issued: 2018
Potential effects of different salinities on the survival of the mangrove crab, Uca urvillei and its associated chemoautotrophic bacterial symbionts
- Mbobo, Tumeka https://orcid.org/0000-0002-0159-6569
- Authors: Mbobo, Tumeka https://orcid.org/0000-0002-0159-6569
- Date: 2015-06
- Subjects: Mangrove ecology http://id.loc.gov/authorities/subjects/sh85080528 , Crabs--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19225 , vital:43033
- Description: The ability of natural populations to maintain fitness is important to their long-term persistence and has further relevance in the light of climate change scenarios. Fitness is however also influenced strongly by interactions with other species of the community. It is, therefore, important to focus on how environmental change can alter key biological interactions. The present study aimed to investigate the effects of different salinity levels on one species of mangrove crab, Uca urvillei and the associated chemoautotrophic bacterial symbionts, from the Mngazana estuary, South Africa. To examine the influence of different salinities over time on the symbiotic bacterial community, salinity experiments were set up, choosing three salinity exposures (5, 20 and 35percent) and four time exposures (3, 7, 14 and 21 days). The results showed that microbial community associated with U. urvillei was generally stable throughout the three salinity treatments, while the survival of the host (crab), was influenced by high salinities, particularly after day 14. Overall, the results of this study suggest that over time, environmental salinity (35percent) has the potential to affect significantly the physiology of U. urvillei, but this might not necessarily be the case for the associated microbial communities. The modes at which the significant symbionts are transferred from mother to offspring were also investigated by analysing the bacterial profiles from eggs, ovigerous and non-ovigerous females, along with mud. The results were fairly complex, but with significant differences in the bacterial communities of eggs from mud and females. These differences were driven mostly by two dominant phyla: Actinobacteria and Proteobacteria. The presence of both these phyla throughout the categories (even though in different percentages) suggest that U. urvillei might employ a mixed mode strategy of acquiring and maintaining the bacterial symbionts. Overall, this study contributes to further understand the dynamic and complex effects of environmental Abstract ii change on symbiotic communities, with overall potential cascading repercussions to the persistence of mangrove systems. , Thesis (MSc) (Zoology) -- Faculty of Science and Agriculture, 2015
- Full Text:
- Date Issued: 2015-06
- Authors: Mbobo, Tumeka https://orcid.org/0000-0002-0159-6569
- Date: 2015-06
- Subjects: Mangrove ecology http://id.loc.gov/authorities/subjects/sh85080528 , Crabs--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19225 , vital:43033
- Description: The ability of natural populations to maintain fitness is important to their long-term persistence and has further relevance in the light of climate change scenarios. Fitness is however also influenced strongly by interactions with other species of the community. It is, therefore, important to focus on how environmental change can alter key biological interactions. The present study aimed to investigate the effects of different salinity levels on one species of mangrove crab, Uca urvillei and the associated chemoautotrophic bacterial symbionts, from the Mngazana estuary, South Africa. To examine the influence of different salinities over time on the symbiotic bacterial community, salinity experiments were set up, choosing three salinity exposures (5, 20 and 35percent) and four time exposures (3, 7, 14 and 21 days). The results showed that microbial community associated with U. urvillei was generally stable throughout the three salinity treatments, while the survival of the host (crab), was influenced by high salinities, particularly after day 14. Overall, the results of this study suggest that over time, environmental salinity (35percent) has the potential to affect significantly the physiology of U. urvillei, but this might not necessarily be the case for the associated microbial communities. The modes at which the significant symbionts are transferred from mother to offspring were also investigated by analysing the bacterial profiles from eggs, ovigerous and non-ovigerous females, along with mud. The results were fairly complex, but with significant differences in the bacterial communities of eggs from mud and females. These differences were driven mostly by two dominant phyla: Actinobacteria and Proteobacteria. The presence of both these phyla throughout the categories (even though in different percentages) suggest that U. urvillei might employ a mixed mode strategy of acquiring and maintaining the bacterial symbionts. Overall, this study contributes to further understand the dynamic and complex effects of environmental Abstract ii change on symbiotic communities, with overall potential cascading repercussions to the persistence of mangrove systems. , Thesis (MSc) (Zoology) -- Faculty of Science and Agriculture, 2015
- Full Text:
- Date Issued: 2015-06
Evaluation and identification of microbial contaminants in polyherbal medicines used for the treatment of tuberculosis in Amathole District Municipality, Eastern Cape Province, South Africa
- Authors: Famewo, Elizabeth Bosede
- Date: 2018
- Subjects: Tuberculosis -- Treatment -- South Africa Mycobacterial diseases -- South Africa -- Eastern Cape Medicinal plants -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9680 , vital:34818
- Description: Tuberculosis is caused by Mycobacterium tuberculosis. The emergence of drug-resistant strains of this organism has become a global public health problem. In the continuing search for effective treatment, polyherbal medicines offer a great hope in the development of alternative drugs for the treatment of tuberculosis. The use of herbal formulations for therapeutic purposes has significantly increased in the developed and developing countries because of their curative property, less toxicity and minimal side effects. However, there is little information on their safety and effectiveness in the literature. To address this, polyherbal medicines used for the treatment of tuberculosis in the Eastern Cape Province of South Africa were evaluated. Ethno-medicinal survey was conducted through semi-structured questionnaires coupled with informal conversations with the herbal sellers in five communities in the study area. Bacterial and fungal DNA was extracted from the polyherbal medicines purchased. A fragment of the bacterial 16S rRNA gene and internal transcribed spacer region of the fungal rRNA operon were amplified with universal primers 27F and 518R, and ITS1 and ITS4 respectively. Following standard procedures, the amplicons were finally run on Illumina’s MiSeq platform. Furthermore, the remedies were screened against Mycobacterium tuberculosis H37Rv using Middlebrook 7H9 media and MGIT BACTEC 960 system. Agar dilution method was used to determine the minimum inhibitory concentration (MIC) of the remedies against eight bacteria and three fungi isolates. The herbal preparations were assayed for their toxicity using hatchability success and larval mortality of Artemia salina Leach. Finally, their nutritive properties were analysed using an inductively coupled plasma optical emission spectrometer for mineral analysis while the vitamins were determined using standardized methods A total of nine polyherbal preparations were collected. The herbs used for the preparation of these remedies belong to 20 families. Apiaceae [5(25 percent)] was the most prominent plant family used, followed by Liliaceae [4(20 percent)], Strychnaceae [4(20 percent)], Rutaceae [4(20 percent)] and Hypoxidaceae [3(15 percent)]. The two most frequently used plants were Allium sativum L. (Liliaceae) and Strychnos decussata (Pappe) Gilg. (Strychnaceae). Rhizomes was the most common parts used, followed by the roots and barks. The herbal medicines were prepared mainly by infusion and decoction. The presences of pathogenic and non-pathogenic bacteria were identified in the polyherbal medicines. Generally, the most common bacteria identified from the samples were Bacillus sp., Enterobacter sp., Klebsiella sp., Rahnella sp., Paenibacillus sp., Clostridium sp. and Pantoea sp. The predominant mycoflora obtained belongs to different genera or species of fungi; these include Alternaria, Candida, Ramularia, Cladosporium, Penicillium, Aspergillus and Malassezia. The susceptibility testing revealed that all the remedies contain anti-tubercular activity against M. tuberculosis H37Rv at concentrations below 50 ug/ml. Seven of the polyherbal preparations showed activity at concentrations below 25 ug/ml. The MIC values exhibited inhibitory activity at 1.562 μg/ml. However, isoniazid showed more inhibitory activity against M. tuberculosis at 0.05 μg/ml when compared to the polyherbal remedies. The inhibitory activity of the polyherbal medicines based on the overall MIC revealed that Hogsback first site (HBfs) and Fort Beaufort (FB) remedies were the most active remedies against the bacterial isolates at the concentration of 2.5 mg/mL. Among the nine herbal formulations, only King Williams Town site A (KWTa) remedy showed activity against Aspergillus niger and Aspergillus fumigatus with the MIC valve of 2.5 mg/mL. While King Williams Town site C (KWTc) and Hogsback third site (HBts) had the highest activity at 1.25 mg/mL against Candida albicans, the remaining remedies were active at 2.5 mg/mL. The percentage hatchability of 44.42 percent, 42.96 percent and 39.70 percent were observed in A. salina cysts incubated with herbal preparations from KWTa, HBfs and HBts respectively. The hatching success of the cysts in these remedies was significantly higher than the positive control (nystatin) and the negative control (sea water) at p < 0.05. The mortality of A. salina nauplii incubated in Alice (AL), King Williams Town site B (KWTb) and KWTc remedies were significantly higher than when larvae were incubated in both controls. Based on Meyer’s index, the LD50 of each polyherbal medicine was between 2.9 and 4.0 mg/ml, the LD50 values greater than 1 mg/ml, an indication that they are not toxic. The polyherbal preparations were found to be rich in vitamins and mineral nutrients. Calcium was the highest macronutrient detected while the lowest nutrient was phosphorus. Iron was the highest micronutrient in the majority of the polyherbal preparations while the lowest value was recorded for copper. Vitamin C was absent in the herbal preparations while vitamin A and E were detected. This study provides significant ethno-medicinal information on polyherbal medicines used for the treatment of TB in the study area. The presence of the identified bacteria and fungi in the herbal formulations is a cause for concern. However, the ability of the remedies to possess activity against Mycobacterium tuberculosis and other pathogenic microorganisms associated with tuberculosis infection makes them potential sources of new antimycobacterial agents. Also, they are rich sources of mineral nutrients, and are as well non-toxic, thus, they are safe for consumption. In view of their anti-tubercular properties, this study has provided a better understanding of the reasons why TB-patients make use of these polyherbal formulations. Also, the study supports the folkloric use of polyherbal medicines in the treatment of tuberculosis in the Eastern Cape Province, South Africa.
- Full Text:
- Date Issued: 2018
- Authors: Famewo, Elizabeth Bosede
- Date: 2018
- Subjects: Tuberculosis -- Treatment -- South Africa Mycobacterial diseases -- South Africa -- Eastern Cape Medicinal plants -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9680 , vital:34818
- Description: Tuberculosis is caused by Mycobacterium tuberculosis. The emergence of drug-resistant strains of this organism has become a global public health problem. In the continuing search for effective treatment, polyherbal medicines offer a great hope in the development of alternative drugs for the treatment of tuberculosis. The use of herbal formulations for therapeutic purposes has significantly increased in the developed and developing countries because of their curative property, less toxicity and minimal side effects. However, there is little information on their safety and effectiveness in the literature. To address this, polyherbal medicines used for the treatment of tuberculosis in the Eastern Cape Province of South Africa were evaluated. Ethno-medicinal survey was conducted through semi-structured questionnaires coupled with informal conversations with the herbal sellers in five communities in the study area. Bacterial and fungal DNA was extracted from the polyherbal medicines purchased. A fragment of the bacterial 16S rRNA gene and internal transcribed spacer region of the fungal rRNA operon were amplified with universal primers 27F and 518R, and ITS1 and ITS4 respectively. Following standard procedures, the amplicons were finally run on Illumina’s MiSeq platform. Furthermore, the remedies were screened against Mycobacterium tuberculosis H37Rv using Middlebrook 7H9 media and MGIT BACTEC 960 system. Agar dilution method was used to determine the minimum inhibitory concentration (MIC) of the remedies against eight bacteria and three fungi isolates. The herbal preparations were assayed for their toxicity using hatchability success and larval mortality of Artemia salina Leach. Finally, their nutritive properties were analysed using an inductively coupled plasma optical emission spectrometer for mineral analysis while the vitamins were determined using standardized methods A total of nine polyherbal preparations were collected. The herbs used for the preparation of these remedies belong to 20 families. Apiaceae [5(25 percent)] was the most prominent plant family used, followed by Liliaceae [4(20 percent)], Strychnaceae [4(20 percent)], Rutaceae [4(20 percent)] and Hypoxidaceae [3(15 percent)]. The two most frequently used plants were Allium sativum L. (Liliaceae) and Strychnos decussata (Pappe) Gilg. (Strychnaceae). Rhizomes was the most common parts used, followed by the roots and barks. The herbal medicines were prepared mainly by infusion and decoction. The presences of pathogenic and non-pathogenic bacteria were identified in the polyherbal medicines. Generally, the most common bacteria identified from the samples were Bacillus sp., Enterobacter sp., Klebsiella sp., Rahnella sp., Paenibacillus sp., Clostridium sp. and Pantoea sp. The predominant mycoflora obtained belongs to different genera or species of fungi; these include Alternaria, Candida, Ramularia, Cladosporium, Penicillium, Aspergillus and Malassezia. The susceptibility testing revealed that all the remedies contain anti-tubercular activity against M. tuberculosis H37Rv at concentrations below 50 ug/ml. Seven of the polyherbal preparations showed activity at concentrations below 25 ug/ml. The MIC values exhibited inhibitory activity at 1.562 μg/ml. However, isoniazid showed more inhibitory activity against M. tuberculosis at 0.05 μg/ml when compared to the polyherbal remedies. The inhibitory activity of the polyherbal medicines based on the overall MIC revealed that Hogsback first site (HBfs) and Fort Beaufort (FB) remedies were the most active remedies against the bacterial isolates at the concentration of 2.5 mg/mL. Among the nine herbal formulations, only King Williams Town site A (KWTa) remedy showed activity against Aspergillus niger and Aspergillus fumigatus with the MIC valve of 2.5 mg/mL. While King Williams Town site C (KWTc) and Hogsback third site (HBts) had the highest activity at 1.25 mg/mL against Candida albicans, the remaining remedies were active at 2.5 mg/mL. The percentage hatchability of 44.42 percent, 42.96 percent and 39.70 percent were observed in A. salina cysts incubated with herbal preparations from KWTa, HBfs and HBts respectively. The hatching success of the cysts in these remedies was significantly higher than the positive control (nystatin) and the negative control (sea water) at p < 0.05. The mortality of A. salina nauplii incubated in Alice (AL), King Williams Town site B (KWTb) and KWTc remedies were significantly higher than when larvae were incubated in both controls. Based on Meyer’s index, the LD50 of each polyherbal medicine was between 2.9 and 4.0 mg/ml, the LD50 values greater than 1 mg/ml, an indication that they are not toxic. The polyherbal preparations were found to be rich in vitamins and mineral nutrients. Calcium was the highest macronutrient detected while the lowest nutrient was phosphorus. Iron was the highest micronutrient in the majority of the polyherbal preparations while the lowest value was recorded for copper. Vitamin C was absent in the herbal preparations while vitamin A and E were detected. This study provides significant ethno-medicinal information on polyherbal medicines used for the treatment of TB in the study area. The presence of the identified bacteria and fungi in the herbal formulations is a cause for concern. However, the ability of the remedies to possess activity against Mycobacterium tuberculosis and other pathogenic microorganisms associated with tuberculosis infection makes them potential sources of new antimycobacterial agents. Also, they are rich sources of mineral nutrients, and are as well non-toxic, thus, they are safe for consumption. In view of their anti-tubercular properties, this study has provided a better understanding of the reasons why TB-patients make use of these polyherbal formulations. Also, the study supports the folkloric use of polyherbal medicines in the treatment of tuberculosis in the Eastern Cape Province, South Africa.
- Full Text:
- Date Issued: 2018
Synthesis of bioethanol from lignocellulosic materials: A focus on grass and waste paper as raw materials
- Authors: Vala, Mavula Kikwe
- Date: 2009-12
- Subjects: Ethanol as fuel , Biomass energy , Lignocellulose -- Biotechnology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24499 , vital:63049
- Description: Biofuels are currently recognized as not only a necessity, but an inevitable pathway to secure the planet future energy needs. Food crops have been used (so far) as the biomass for bioethanol and biodiesel production. This has increased concerns over food security and led to the search for diversification and alternative feedstocks for biofuel production. The use of lignocellulosic materials, the most abundant, low cost and easy feedstock to harvest for bioethanol purpose, involves challenging production processes. Several approaches have been used to facilitate the breakdown of the biopolymer structure to produce fermentable sugars that can be converted to ethanol. Most of the approaches have used high temperatures and pressures and have often led to the production of inhibitors of fermentation. In this study, lignocellulosic materials from grass and newsprint were investigated as sources of biomass for bioethanol production using a chemical route (sulfuric acid hydrolysis) which made use of temperatures below 100°C at normal atmospheric pressure. Fermentation of toxic lignocellulosic hydrolyzates was possible after the development of a method for inhibitors removal. The method used treated wood chips as a stationary phase in a chromatographic column to remove inhibitors. This method is expected to be extended to applications such as in municipal wastewater treatment. Sugar yields of 22.26 and 8.9 g/L of hydrolyzate; and an ethanol yield of 184.5 and 130.4 mg/mL of must were achieved for 5g grass and newsprint respectively using optimum conditions of 2percent H2SO4 at 97.5°C for grass and 0.5percent H2SO4 at 97.5°C for newsprint during the hydrolysis process. Pure cellulose was used as a control for the biomass where 254.1 g/L of fermentable sugars were recovered from soluble cellulose and the yield of ethanol was 201.8 mg/mL. , Thesis (MSc) -- Faculty of Science and Agriculture, 2009
- Full Text:
- Date Issued: 2009-12
- Authors: Vala, Mavula Kikwe
- Date: 2009-12
- Subjects: Ethanol as fuel , Biomass energy , Lignocellulose -- Biotechnology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24499 , vital:63049
- Description: Biofuels are currently recognized as not only a necessity, but an inevitable pathway to secure the planet future energy needs. Food crops have been used (so far) as the biomass for bioethanol and biodiesel production. This has increased concerns over food security and led to the search for diversification and alternative feedstocks for biofuel production. The use of lignocellulosic materials, the most abundant, low cost and easy feedstock to harvest for bioethanol purpose, involves challenging production processes. Several approaches have been used to facilitate the breakdown of the biopolymer structure to produce fermentable sugars that can be converted to ethanol. Most of the approaches have used high temperatures and pressures and have often led to the production of inhibitors of fermentation. In this study, lignocellulosic materials from grass and newsprint were investigated as sources of biomass for bioethanol production using a chemical route (sulfuric acid hydrolysis) which made use of temperatures below 100°C at normal atmospheric pressure. Fermentation of toxic lignocellulosic hydrolyzates was possible after the development of a method for inhibitors removal. The method used treated wood chips as a stationary phase in a chromatographic column to remove inhibitors. This method is expected to be extended to applications such as in municipal wastewater treatment. Sugar yields of 22.26 and 8.9 g/L of hydrolyzate; and an ethanol yield of 184.5 and 130.4 mg/mL of must were achieved for 5g grass and newsprint respectively using optimum conditions of 2percent H2SO4 at 97.5°C for grass and 0.5percent H2SO4 at 97.5°C for newsprint during the hydrolysis process. Pure cellulose was used as a control for the biomass where 254.1 g/L of fermentable sugars were recovered from soluble cellulose and the yield of ethanol was 201.8 mg/mL. , Thesis (MSc) -- Faculty of Science and Agriculture, 2009
- Full Text:
- Date Issued: 2009-12
Characterization of bioflocculants produced by consortia of three marine bacteria belonging to the genera bacillus and cobetia previously isolated from the bottom sediment of Algoa Bay in the Eastern Cape Province of South Africa
- Ugbenyen, Anthony Moses https://orcid.org/0000-0002-1381-3428
- Authors: Ugbenyen, Anthony Moses https://orcid.org/0000-0002-1381-3428
- Date: 2013
- Subjects: Water -- Purification -- Flocculation , Water quality management , Flocculation
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24454 , vital:62804
- Description: The bioflocculant-producing potentials of three marine bacteria isolated from the sediment samples of Algoa Bay in the Eastern Cape Province of South Africa were assessed. Analysis of the partial nucleotide sequence of the 16S rDNA of the bacteria revealed 99 percent, 99 percent, and 98 percent similarity to Cobetia sp. L222, Bacillus sp. A-5A, and Bacillus sp. HXG-C1 respectively and the sequence was deposited in GenBank as Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert (accession number JF799092, JF799093, and HQ537128 respectively). Cultivation condition studies for Cobetia sp. OAUIFE revealed that bioflocculant production was optimal with an inoculum size of 2 percent (v/v), initial pH of 6.0, Mn2+ as the metal ion, and glucose as the carbon source. Metal ions, including Na+, K+, Li+, Ca2+and Mg2+ stimulated bioflocculant production resulting in flocculating activity of above 90 percent. This crude bioflocculant is thermally stable, with about 78 percent of its flocculating activity remaining after heating at 100 oC for 25 min. Analysis of the purified bioflocculant revealed it to be an acidic extracellular polysaccharide. FTIR analysis revealed the presence of methoxyl, hydroxyl, and carboxyl - groups in the compound bioflocculant and SEM micrograph of the bioflocculant revealed a crystal-linear structure. On the other hand, bioflocculant production by Bacillus sp. MAYA was optimal when glucose (95.6 percent flocculating activity) and ammonium nitrate (83.3 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 2 percent (v/v); initial pH 6; and Ca2+ as coagulant aid. Chemical analysis of the purified bioflocculant shows that it is composed of uronic acid, neutral sugar and protein. FTIR analysis also revealed the presence of methoxyl, hydroxyl, carboxyl and amino- groups in this bioflocculant. The bioflocculant is thermostable with about 65.6 percent residual flocculating activity retained after heating the bioflocculant at 100 oC for 25 min. However bioflocculant production by Bacillus sp. Gilbert was optimal when sodium carbonate (95.2 percent flocculating activity) and potassium nitrate (76.6 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 3 percent (v/v); initial pH 9; and Al3+ as cation. The crude bioflocculant retained 44.2 percent residual flocculating activity after heating at 100 oC for 15 min. FTIR analysis reveals the presence of hydroxyl, carboxyl and methylene - groups in the compound bioflocculant. SEM micrograph of the bioflocculant revealed an amorphous compound. The consortia of these bacteria strains also produced bioflocculants with high flocculating activities which were highly efficient in removing turbidity and chemical oxygen demand (COD) from brewery wastewater, diary wastewater and river water. The bioflocculants from the consortia seemed better than traditional flocculants such as alum . The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE and Bacillus sp. MAYA showed that this extracellular bioflocculant, composed of 66percent uronic acid and 31percent protein and an optimum flocculation (90 percent) of kaolin suspension, when the dosage concentration was 0.8 mg/ml, under weak alkaline pH of 8, and Ca2+ as a coagulant aid. The bioflocculant is thermally stable, with a high residual flocculating activity of 86.7 percent, 89.3 percent and 87.0 percent after heating at 50 oC, 80 oC and 100 oC for 25 min respectively. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl functional groups. Scanning electron microscopy (SEM) image revealed a crystal-linear spongy-like bioflocculant structure and EDX analysis of the purified bioflocculant showed that the elemental composition in mass proportion of C,N,O,S and P was 6.67:6.23:37.55:0.38:4.42 (percent w/w). However, the characteristics of the bioflocculant produced by the consortium of Cobetia sp OAUIFE and Bacillus sp. Gilbert showed an optimum flocculation (90 percent) of kaolin suspension when the dosage concentration was 0.2 mg/ml, under neutral pH of 7, and Ca2+ as a coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl and carbonyl functional groups. Scanning electron microscopy (SEM) image revealed an amorphous morphology. On the other hand the bioflocculant produced by the consortium of Bacillus sp. MAYA and Bacillus sp. Gilbert showed similar characteristic with the bioflocculant from the consortium of Cobetia sp. OAUIFE and Bacillus sp. Gilbert except for Al3+ being the preferred coagulant aid. The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert showed an optimum flocculation (87 percent) of kaolin suspension when the dosage concentration was 1.0 mg/ml. Under strong alkaline pH of 12, flocculating activity reached (95 percent) when Al3+ was the coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl and phosphoryl functional groups. Scanning electron microscopy (SEM) image revealed a flaky amorphous morphological structure. Due to the excellent COD and turbidity removal efficiencies of the bioflocculants produced by the consortia, these make those attractive candidates for use in water and wastewater treatment. , Thesis (PhD) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
- Authors: Ugbenyen, Anthony Moses https://orcid.org/0000-0002-1381-3428
- Date: 2013
- Subjects: Water -- Purification -- Flocculation , Water quality management , Flocculation
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24454 , vital:62804
- Description: The bioflocculant-producing potentials of three marine bacteria isolated from the sediment samples of Algoa Bay in the Eastern Cape Province of South Africa were assessed. Analysis of the partial nucleotide sequence of the 16S rDNA of the bacteria revealed 99 percent, 99 percent, and 98 percent similarity to Cobetia sp. L222, Bacillus sp. A-5A, and Bacillus sp. HXG-C1 respectively and the sequence was deposited in GenBank as Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert (accession number JF799092, JF799093, and HQ537128 respectively). Cultivation condition studies for Cobetia sp. OAUIFE revealed that bioflocculant production was optimal with an inoculum size of 2 percent (v/v), initial pH of 6.0, Mn2+ as the metal ion, and glucose as the carbon source. Metal ions, including Na+, K+, Li+, Ca2+and Mg2+ stimulated bioflocculant production resulting in flocculating activity of above 90 percent. This crude bioflocculant is thermally stable, with about 78 percent of its flocculating activity remaining after heating at 100 oC for 25 min. Analysis of the purified bioflocculant revealed it to be an acidic extracellular polysaccharide. FTIR analysis revealed the presence of methoxyl, hydroxyl, and carboxyl - groups in the compound bioflocculant and SEM micrograph of the bioflocculant revealed a crystal-linear structure. On the other hand, bioflocculant production by Bacillus sp. MAYA was optimal when glucose (95.6 percent flocculating activity) and ammonium nitrate (83.3 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 2 percent (v/v); initial pH 6; and Ca2+ as coagulant aid. Chemical analysis of the purified bioflocculant shows that it is composed of uronic acid, neutral sugar and protein. FTIR analysis also revealed the presence of methoxyl, hydroxyl, carboxyl and amino- groups in this bioflocculant. The bioflocculant is thermostable with about 65.6 percent residual flocculating activity retained after heating the bioflocculant at 100 oC for 25 min. However bioflocculant production by Bacillus sp. Gilbert was optimal when sodium carbonate (95.2 percent flocculating activity) and potassium nitrate (76.6 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 3 percent (v/v); initial pH 9; and Al3+ as cation. The crude bioflocculant retained 44.2 percent residual flocculating activity after heating at 100 oC for 15 min. FTIR analysis reveals the presence of hydroxyl, carboxyl and methylene - groups in the compound bioflocculant. SEM micrograph of the bioflocculant revealed an amorphous compound. The consortia of these bacteria strains also produced bioflocculants with high flocculating activities which were highly efficient in removing turbidity and chemical oxygen demand (COD) from brewery wastewater, diary wastewater and river water. The bioflocculants from the consortia seemed better than traditional flocculants such as alum . The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE and Bacillus sp. MAYA showed that this extracellular bioflocculant, composed of 66percent uronic acid and 31percent protein and an optimum flocculation (90 percent) of kaolin suspension, when the dosage concentration was 0.8 mg/ml, under weak alkaline pH of 8, and Ca2+ as a coagulant aid. The bioflocculant is thermally stable, with a high residual flocculating activity of 86.7 percent, 89.3 percent and 87.0 percent after heating at 50 oC, 80 oC and 100 oC for 25 min respectively. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl functional groups. Scanning electron microscopy (SEM) image revealed a crystal-linear spongy-like bioflocculant structure and EDX analysis of the purified bioflocculant showed that the elemental composition in mass proportion of C,N,O,S and P was 6.67:6.23:37.55:0.38:4.42 (percent w/w). However, the characteristics of the bioflocculant produced by the consortium of Cobetia sp OAUIFE and Bacillus sp. Gilbert showed an optimum flocculation (90 percent) of kaolin suspension when the dosage concentration was 0.2 mg/ml, under neutral pH of 7, and Ca2+ as a coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl and carbonyl functional groups. Scanning electron microscopy (SEM) image revealed an amorphous morphology. On the other hand the bioflocculant produced by the consortium of Bacillus sp. MAYA and Bacillus sp. Gilbert showed similar characteristic with the bioflocculant from the consortium of Cobetia sp. OAUIFE and Bacillus sp. Gilbert except for Al3+ being the preferred coagulant aid. The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert showed an optimum flocculation (87 percent) of kaolin suspension when the dosage concentration was 1.0 mg/ml. Under strong alkaline pH of 12, flocculating activity reached (95 percent) when Al3+ was the coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl and phosphoryl functional groups. Scanning electron microscopy (SEM) image revealed a flaky amorphous morphological structure. Due to the excellent COD and turbidity removal efficiencies of the bioflocculants produced by the consortia, these make those attractive candidates for use in water and wastewater treatment. , Thesis (PhD) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
Electrical, photo-thermal and mechanical degradation analysis of degraded single junction amorphous silicon solar modules
- Osayemwenre, Gilbert Omorodion
- Authors: Osayemwenre, Gilbert Omorodion
- Date: 2019
- Subjects: Solar cells Amorphous semiconductors Silicon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15211 , vital:40204
- Description: In this present era of sustainable energy development, photovoltaic modules which are based on amorphous silicon cells have immeasurable prospects of contributing meaningfully to the energy demand of the world at large. The global consciousness of environmental safety issues has birthed the rapid demand for the photovoltaic system. However, the production increase is mainly in bulk-type crystalline (c-Si) solar cells. Thus, to meet the high demand of the market, single junction amorphous silicon (a-Si:H) solar cells production must be encouraged through active research in that regard. This could also help to improve its efficiency and reliability. There has recently been a sharp decrease in the production cost of the bulk Si solar cell, but the a-Si:H solar cell still remains the most economically viable in comparison to the other PV technologies. Companies such as Sharp are currently developing large-scale a-Si:H solar modules that can produce an efficiency of 10.5% after the long-term degradation process. To date, a-Si:H is believed to be one of the most promising thin-film PV technologies (Saito et al., 1993; Hamakawa et al., 1994). The cost of a solar PV manufacturing fell by 6% in 2014 (Santa, 2014), this is in accordance with the 2008 cost production forecast; thus, the cost record stands at 0.20 per watt, as reported by the NPD Solar publisher. Amorphous silicon (a-Si) solar modules generate more kilowatt-hour (kWh) of electricity per kilowatt (kW) than crystalline silicon or other technologies of the same capacity of installation. Furthermore, a-Si:H modules have more functional hours per day. Single junction amorphous silicon (a-Si:H) modules can function beyond the peak sun hours, and they also have a better performance on a cloudy day. vii In other words, a 1kW PV system of a-Si:H is expected to generate more electricity per year in comparison to 1kW PV from other technologies, hence there is a low energy payback time. In this study, commercially available single junction amorphous silicon modules were bought from a local market and they were immediately deployed outdoors. The initial reading of the modules, which served as baseline reading, showed an average of 25% decrease in the modules performance, therefore, there is a need for a long term monitoring process to obtain the best and worst performing modules. Measuring the performance parameters of these PV modules under real sun light (IV) provides a better degradation assessment. This conventional assessment cannot provide an in-depth insight responsible for the variation and degradation of the performance parameters. More obscured parameters like recombination current and ideality factor were obtained from the dark IV measurements. However, this is still superficial in a way. The intrinsic parameters were obtained from scanning probe microscopy (SPM) and CV measurements. The study focuses on the degradation analysis of a-Si:H due to an increase in defect density. A rise in the defect concentration is a huge problem because it causes long-term solar cell degradation, which increases the recombination current and decreases the conversion efficiency. Furthermore, it decreases the photo-generating current and reduces the effective efficiency of the solar device. In other words, the electrical output decreases. This research investigates the reduction in a-Si:H modules’ maximum power, and correlates these with a hot spot formation. A PVPM IV tracer was used for the outdoor characterisation of the module’s temperature profile, while the IR camera was used to analyse the hot spot centre. A four probe IV/CV from NMU was used for the indoor assessment of smaller samples cleaved from both the affected and non-affected regions to characterise the electrical variations across the module viii samples. To be precise, in this study, a naturally degraded single junction amorphous silicon module was delaminated and its mechanical properties were analysed and correlated with the contact potential from a Kelvin probe force microscopy (KPFM).
- Full Text:
- Date Issued: 2019
- Authors: Osayemwenre, Gilbert Omorodion
- Date: 2019
- Subjects: Solar cells Amorphous semiconductors Silicon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15211 , vital:40204
- Description: In this present era of sustainable energy development, photovoltaic modules which are based on amorphous silicon cells have immeasurable prospects of contributing meaningfully to the energy demand of the world at large. The global consciousness of environmental safety issues has birthed the rapid demand for the photovoltaic system. However, the production increase is mainly in bulk-type crystalline (c-Si) solar cells. Thus, to meet the high demand of the market, single junction amorphous silicon (a-Si:H) solar cells production must be encouraged through active research in that regard. This could also help to improve its efficiency and reliability. There has recently been a sharp decrease in the production cost of the bulk Si solar cell, but the a-Si:H solar cell still remains the most economically viable in comparison to the other PV technologies. Companies such as Sharp are currently developing large-scale a-Si:H solar modules that can produce an efficiency of 10.5% after the long-term degradation process. To date, a-Si:H is believed to be one of the most promising thin-film PV technologies (Saito et al., 1993; Hamakawa et al., 1994). The cost of a solar PV manufacturing fell by 6% in 2014 (Santa, 2014), this is in accordance with the 2008 cost production forecast; thus, the cost record stands at 0.20 per watt, as reported by the NPD Solar publisher. Amorphous silicon (a-Si) solar modules generate more kilowatt-hour (kWh) of electricity per kilowatt (kW) than crystalline silicon or other technologies of the same capacity of installation. Furthermore, a-Si:H modules have more functional hours per day. Single junction amorphous silicon (a-Si:H) modules can function beyond the peak sun hours, and they also have a better performance on a cloudy day. vii In other words, a 1kW PV system of a-Si:H is expected to generate more electricity per year in comparison to 1kW PV from other technologies, hence there is a low energy payback time. In this study, commercially available single junction amorphous silicon modules were bought from a local market and they were immediately deployed outdoors. The initial reading of the modules, which served as baseline reading, showed an average of 25% decrease in the modules performance, therefore, there is a need for a long term monitoring process to obtain the best and worst performing modules. Measuring the performance parameters of these PV modules under real sun light (IV) provides a better degradation assessment. This conventional assessment cannot provide an in-depth insight responsible for the variation and degradation of the performance parameters. More obscured parameters like recombination current and ideality factor were obtained from the dark IV measurements. However, this is still superficial in a way. The intrinsic parameters were obtained from scanning probe microscopy (SPM) and CV measurements. The study focuses on the degradation analysis of a-Si:H due to an increase in defect density. A rise in the defect concentration is a huge problem because it causes long-term solar cell degradation, which increases the recombination current and decreases the conversion efficiency. Furthermore, it decreases the photo-generating current and reduces the effective efficiency of the solar device. In other words, the electrical output decreases. This research investigates the reduction in a-Si:H modules’ maximum power, and correlates these with a hot spot formation. A PVPM IV tracer was used for the outdoor characterisation of the module’s temperature profile, while the IR camera was used to analyse the hot spot centre. A four probe IV/CV from NMU was used for the indoor assessment of smaller samples cleaved from both the affected and non-affected regions to characterise the electrical variations across the module viii samples. To be precise, in this study, a naturally degraded single junction amorphous silicon module was delaminated and its mechanical properties were analysed and correlated with the contact potential from a Kelvin probe force microscopy (KPFM).
- Full Text:
- Date Issued: 2019
Beef quality, oxidative stability and fatty acid composition of Nguni heifers fed diets with incremental levels of Opuntia ficus-indica (cactus) cladodes
- Authors: Mkhosi, Silungile
- Date: 2020
- Subjects: Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18732 , vital:42728
- Description: The objective of the study was to determine meat quality, fatty acid (FA) composition and shelf-life stability of longissimus muscle of Nguni heifers fed incremental levels of Opuntia ficus-indica (cactus) cladodes. A total of 32 heifers aged 36 months were allocated randomly to four dietary treatments: 10% cactus, 20% cactus, commercial and control diets for 90 days. The longissimus thoracis et lumborum (LTL) samples were taken from each carcass for the determination of meat quality, retail shelf-life stability and FA composition. Diet had no effect (P > 0.05) on pH and drip display, however, there was an increase in drip display with ageing time (P ≤ 0.05). Meat colour attributes (L* a* b* and C*) were influenced by diet, with 20% cactus diet having lower L* values compared to other diets (P ≤ 0.05). During a 14-day retail display, a diet day interaction was observed for hue angle with the cactus diets having the lowest values at day 14 of display compared to the other diets (P ≤ 0.05). Differences in meat from heifers fed different diets were observed with 20% cactus accounting for significantly (P ≤ 0.05) higher levels of deoxymyoglobin and the lowest levels of oxymyoglobin. Thawing loss and Warner Bratzler shear force decreased (P ≤ 0.05) with ageing period. Meat from heifers fed cactus diets had lower (P ≤ 0.05) proportions of oleic acid (C18:1n9c) and total MUFA, higher (P ≤ 0.05) proportions of total SFA, C15:1, C17:1, linoleic acid (C18:2n6c) and total PUFA. The control diet produced meat with the highest thiobarbituric acid reactive substances (TBARS) values compared to other diets (P ≤ 0.05) and with ageing TBARS values increased (P ≤ 0.05). Diet showed an effect (P ≤ 0.05) on sensory attributes such as overall tenderness and mouth feel with cactus diets accounting for lower scores. However, juiciness, overall tenderness, grassy and animal like attributes increased with ageing (P ≤ 0.05). Inclusion of cactus in the diet did not produce any adverse effects on meat quality, fatty acid composition, lipid oxidation and sensory quality. Therefore, it can be concluded that inclusion of cactus in Nguni heifer finisher diets up to 20% can improve meat quality.
- Full Text:
- Date Issued: 2020
- Authors: Mkhosi, Silungile
- Date: 2020
- Subjects: Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18732 , vital:42728
- Description: The objective of the study was to determine meat quality, fatty acid (FA) composition and shelf-life stability of longissimus muscle of Nguni heifers fed incremental levels of Opuntia ficus-indica (cactus) cladodes. A total of 32 heifers aged 36 months were allocated randomly to four dietary treatments: 10% cactus, 20% cactus, commercial and control diets for 90 days. The longissimus thoracis et lumborum (LTL) samples were taken from each carcass for the determination of meat quality, retail shelf-life stability and FA composition. Diet had no effect (P > 0.05) on pH and drip display, however, there was an increase in drip display with ageing time (P ≤ 0.05). Meat colour attributes (L* a* b* and C*) were influenced by diet, with 20% cactus diet having lower L* values compared to other diets (P ≤ 0.05). During a 14-day retail display, a diet day interaction was observed for hue angle with the cactus diets having the lowest values at day 14 of display compared to the other diets (P ≤ 0.05). Differences in meat from heifers fed different diets were observed with 20% cactus accounting for significantly (P ≤ 0.05) higher levels of deoxymyoglobin and the lowest levels of oxymyoglobin. Thawing loss and Warner Bratzler shear force decreased (P ≤ 0.05) with ageing period. Meat from heifers fed cactus diets had lower (P ≤ 0.05) proportions of oleic acid (C18:1n9c) and total MUFA, higher (P ≤ 0.05) proportions of total SFA, C15:1, C17:1, linoleic acid (C18:2n6c) and total PUFA. The control diet produced meat with the highest thiobarbituric acid reactive substances (TBARS) values compared to other diets (P ≤ 0.05) and with ageing TBARS values increased (P ≤ 0.05). Diet showed an effect (P ≤ 0.05) on sensory attributes such as overall tenderness and mouth feel with cactus diets accounting for lower scores. However, juiciness, overall tenderness, grassy and animal like attributes increased with ageing (P ≤ 0.05). Inclusion of cactus in the diet did not produce any adverse effects on meat quality, fatty acid composition, lipid oxidation and sensory quality. Therefore, it can be concluded that inclusion of cactus in Nguni heifer finisher diets up to 20% can improve meat quality.
- 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
Evaluation of groundwater potential using neotectonics and geophysics in the context of post Karoo tectonic framework around Fort Beaufort and Smithfield, Eastern Cape, South Africa
- Authors: Ndlovu, Nkosilathi
- Date: 2017
- Subjects: Neotectonics -- South Africa -- Eastern Cape Groundwater -- South Africa -- Eastern Cape Geophysical surveys -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12687 , vital:39299
- Description: Geological and geophysical methods were used to investigate the Karoo area extending from longitudes 25.50 E to 27.50 E and latitudes 300 S to 330 S in South Africa, particularly Fort Beaufort, Aliwal North, Venterstad and Smithfield. The geology of the area is dominated by the upper Beaufort Group (Adelaide Subgroup) with an extensive network of dolerite sills and dykes that intruded the sedimentary sequence. A relationship between neotectonics, post-Karoo tectonics, groundwater and lithology was investigated to locate suitable groundwater potential sites. Apart from studying the role of neotectonics and the post Karoo tectonics, this research aims at generating groundwater targets to alleviate water shortages mainly for farming and livestock, and prove that neotectonics is still active. Methodologies adopted for obtaining these results included a comprehensive literature review, thin section analysis, scanning electron microscopy, geophysical investigation (magnetic, gravity, and vertical electrical sounding), and the application of Geographical Information Systems (GIS) and remote sensing. Twenty samples were collected at various locations within the study area and were analyzed using the petrographic microscope while others were analyzed with the Scanning Electron Microscopic (SEM) combined with an Energy dispersive x-ray spectrometry. The results show that the rocks are fractured, porous and have variable mineralogy (presence of heavy minerals) within the rocks. The use of Geographical Information Systems (GIS) and remote sensing in geological surveys, especially hydrogeology, has gained momentum over the past few years. This research is no exception as ArcMap software was used to create a map of seismic epicentres of the Eastern Cape Province. From the map it can be observed that seismicity still occurs and thus leading to the notion of neotectonics being active. Lineaments were also automatically extracted using the ENVI 5.1 and Geomatica 2013 software. Lineaments are zones of weakness in the subsurface of the Earth and are very important in locating groundwater potential sites. Geophysical techniques are essential and highly accurate for groundwater studies. Gravity and magnetic techniques were applied on data which was supplied as grids. Analysis using Geosoft Oasis 8.3 revealed extensive lineaments and ring like patterns and these were inferred to be dolerite intrusions (sills and dykes). The morphology of the intrusions help in identifying possible groundwater potential zones and thus they should be investigated. Vertical electrical sounding (VES) technique using the Schlumberger array was carried out at three sites (Fort Beaufort fracture which is possibly related to Quaternary surface uplift of the Amatole-Swaziland axis, splay of the Fort Beaufort fracture and at a site which showed high groundwater potential) to explore subsurface layering. IP2win (lite), 1-D modelling software was used to model the apparent resistivity data to obtain the geoelectric parameters of the subsurface (thickness and resistivity). The VES results are consistent with fractured rocks that aid groundwater movement. The VES data for the three sites was further modelled by the RES2DINV software and this shows low resistivity values associated with loose, water saturated top sandy soil and higher resistivity values associated with sedimentary sequences and dolerite. Moreover, potential sites for citing wells are predicted to be between 79.5 and 128 m on the profile. Further neotectonic studies need to be done, especially on the quaternary sediments as they would have more neotectonic evidence. The use of geophysical techniques for groundwater search need to be intensified, with more emphasis being put to the sedimentary sequences bordered by dolerite intrusions and fractured zones.
- Full Text:
- Date Issued: 2017
- Authors: Ndlovu, Nkosilathi
- Date: 2017
- Subjects: Neotectonics -- South Africa -- Eastern Cape Groundwater -- South Africa -- Eastern Cape Geophysical surveys -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12687 , vital:39299
- Description: Geological and geophysical methods were used to investigate the Karoo area extending from longitudes 25.50 E to 27.50 E and latitudes 300 S to 330 S in South Africa, particularly Fort Beaufort, Aliwal North, Venterstad and Smithfield. The geology of the area is dominated by the upper Beaufort Group (Adelaide Subgroup) with an extensive network of dolerite sills and dykes that intruded the sedimentary sequence. A relationship between neotectonics, post-Karoo tectonics, groundwater and lithology was investigated to locate suitable groundwater potential sites. Apart from studying the role of neotectonics and the post Karoo tectonics, this research aims at generating groundwater targets to alleviate water shortages mainly for farming and livestock, and prove that neotectonics is still active. Methodologies adopted for obtaining these results included a comprehensive literature review, thin section analysis, scanning electron microscopy, geophysical investigation (magnetic, gravity, and vertical electrical sounding), and the application of Geographical Information Systems (GIS) and remote sensing. Twenty samples were collected at various locations within the study area and were analyzed using the petrographic microscope while others were analyzed with the Scanning Electron Microscopic (SEM) combined with an Energy dispersive x-ray spectrometry. The results show that the rocks are fractured, porous and have variable mineralogy (presence of heavy minerals) within the rocks. The use of Geographical Information Systems (GIS) and remote sensing in geological surveys, especially hydrogeology, has gained momentum over the past few years. This research is no exception as ArcMap software was used to create a map of seismic epicentres of the Eastern Cape Province. From the map it can be observed that seismicity still occurs and thus leading to the notion of neotectonics being active. Lineaments were also automatically extracted using the ENVI 5.1 and Geomatica 2013 software. Lineaments are zones of weakness in the subsurface of the Earth and are very important in locating groundwater potential sites. Geophysical techniques are essential and highly accurate for groundwater studies. Gravity and magnetic techniques were applied on data which was supplied as grids. Analysis using Geosoft Oasis 8.3 revealed extensive lineaments and ring like patterns and these were inferred to be dolerite intrusions (sills and dykes). The morphology of the intrusions help in identifying possible groundwater potential zones and thus they should be investigated. Vertical electrical sounding (VES) technique using the Schlumberger array was carried out at three sites (Fort Beaufort fracture which is possibly related to Quaternary surface uplift of the Amatole-Swaziland axis, splay of the Fort Beaufort fracture and at a site which showed high groundwater potential) to explore subsurface layering. IP2win (lite), 1-D modelling software was used to model the apparent resistivity data to obtain the geoelectric parameters of the subsurface (thickness and resistivity). The VES results are consistent with fractured rocks that aid groundwater movement. The VES data for the three sites was further modelled by the RES2DINV software and this shows low resistivity values associated with loose, water saturated top sandy soil and higher resistivity values associated with sedimentary sequences and dolerite. Moreover, potential sites for citing wells are predicted to be between 79.5 and 128 m on the profile. Further neotectonic studies need to be done, especially on the quaternary sediments as they would have more neotectonic evidence. The use of geophysical techniques for groundwater search need to be intensified, with more emphasis being put to the sedimentary sequences bordered by dolerite intrusions and fractured zones.
- Full Text:
- Date Issued: 2017
Land rental policy and land market in Mashonaland East Province, Zimbabwe: implications on farmer decisions, efficiency and equity under A1 and A2 models
- Authors: Tatsvarei , Simbarashe
- Date: 2019
- Subjects: Farms, Small Agricultural extension work
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15666 , vital:40501
- Description: Government promulgated the land rental policy starting in the year 2007. The policy required that A1 (market residual) and A2 (indigenous commercial) farmers pay rentals to the state. Since then, there has also been an emerging trend in which farmers have been renting in and out land, resulting in an informal market for land rentals. The study therefore assessed farmers’ perceptions of land rental policy and evaluated the possible association of this policy to farmers’ decision making on land rental markets as well as its implications on farmers’ efficiency and equity. The study was carried out in Mashonaland East Province of Zimbabwe, covering two districts, Goromonzi and Marondera. The focus was specifically on A1 and A2 farmers, as the rental policy was directed at these resettlement models only and much of the informal land rental markets were prevalent among these categories of farmers. Data collection utilised the survey approach. This was supported by key informant interviews and focus group discussions, with a final sample of 339 households selected using multi-stage sampling method. Survey data were transcribed on CsPro 6, and analysed using Stata, SPSS and Frontier 4.1. Results showed that about a third of household respondents was from Marondera and twothirds was from Goromonzi, while 79% and 21% was A1 and A2 farmers respectively. About 80% was male headed households and the remainder was female headed households. About half of the households were not participating in land rental markets while the other half was split almost equally between those renting-in and renting-out land. In general, A2 farmers were better in agricultural productivity than A1 farmers. It was concluded that farmers had a fairly good knowledge of the agricultural land rental policy enunciated in the Finance Bills. A1 farmers were more knowledgeable than A2 farmers, but no vii significant differences were observed between male and female headed households and farmers involved and not involved in land rental markets. Farmers’ attitudes in relation to policy were categorised as fair, with significant differences based on gender and land market participation. Practice scores showed a poor adherence to policy for all categories of farmers. Overall perceptions of farmers on rental policy was inferred as fair with significant differences existing between land rental market participants and non-participants (autarky). The results of a bivariate Tobit model results showed that the decision to rent-in land was significantly influenced by gender, household income, permanent labour, cultivated area, tenure certainty, irrigable land size and crop diversification. On the other hand, age, permanent labour, irrigable land size and crop diversification significantly influenced farmers’ decisions to rent-out land. The conclusion was that household characteristics, land endowments and transaction costs significantly influenced the decision to rent-in land while the former two were strong in influencing renting-out decisions. Results from the linearized Cobb Douglas model showed that economic efficiency for most farmers was above 50%. Farmers renting-out land under A1 were found to be the most economically efficient, followed by those who were renting-in and least efficient were farmers not participating in land rental markets, though the differences were marginal. For the A2 model, renting-in farmers were the most efficient, followed by those in autarky position, while renting-out farmers were the least. Overall, the most efficient farmers were those renting-in, followed by those renting-out while farmers in autarky were the least efficient. Overall efficiency was higher for A2 farmers than for A1 farmers. For farmers not participating in rental markets, the sources of inefficiency were crop type, crop area and labour. For farmers renting-in, it was proportion of irrigable land, size of irrigable land, crop type, crop area and viii labour, while inefficiency drivers for renting-out farmers were crop type and associated area. Equity analysis showed that participation in land rental markets reduced inequality for farmers in the two districts and male and female headed households. Inequality was increased among A1 farmers and remained unchanged among A2 farmers. Overall, the emerging position was that participation in land rental markets resulted in higher efficiency and reduced inequality in land holding among the sampled farmers. It is recommended that government should be consistent on land rental policy and bring into place effective administration of land rental policy. Government may also consider formal acceptance of land rental markets in light of the marginal efficiency and equity benefits shown in the study. However, formalizing land rental markets alone may not be a panacea to improved efficiency and needs to be supported by other productivity measures given the average efficiency values for farmers. Crop and livestock production based on compatibility with the natural regions and defined minimum size of land should be encouraged to improve efficiency
- Full Text:
- Date Issued: 2019
- Authors: Tatsvarei , Simbarashe
- Date: 2019
- Subjects: Farms, Small Agricultural extension work
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15666 , vital:40501
- Description: Government promulgated the land rental policy starting in the year 2007. The policy required that A1 (market residual) and A2 (indigenous commercial) farmers pay rentals to the state. Since then, there has also been an emerging trend in which farmers have been renting in and out land, resulting in an informal market for land rentals. The study therefore assessed farmers’ perceptions of land rental policy and evaluated the possible association of this policy to farmers’ decision making on land rental markets as well as its implications on farmers’ efficiency and equity. The study was carried out in Mashonaland East Province of Zimbabwe, covering two districts, Goromonzi and Marondera. The focus was specifically on A1 and A2 farmers, as the rental policy was directed at these resettlement models only and much of the informal land rental markets were prevalent among these categories of farmers. Data collection utilised the survey approach. This was supported by key informant interviews and focus group discussions, with a final sample of 339 households selected using multi-stage sampling method. Survey data were transcribed on CsPro 6, and analysed using Stata, SPSS and Frontier 4.1. Results showed that about a third of household respondents was from Marondera and twothirds was from Goromonzi, while 79% and 21% was A1 and A2 farmers respectively. About 80% was male headed households and the remainder was female headed households. About half of the households were not participating in land rental markets while the other half was split almost equally between those renting-in and renting-out land. In general, A2 farmers were better in agricultural productivity than A1 farmers. It was concluded that farmers had a fairly good knowledge of the agricultural land rental policy enunciated in the Finance Bills. A1 farmers were more knowledgeable than A2 farmers, but no vii significant differences were observed between male and female headed households and farmers involved and not involved in land rental markets. Farmers’ attitudes in relation to policy were categorised as fair, with significant differences based on gender and land market participation. Practice scores showed a poor adherence to policy for all categories of farmers. Overall perceptions of farmers on rental policy was inferred as fair with significant differences existing between land rental market participants and non-participants (autarky). The results of a bivariate Tobit model results showed that the decision to rent-in land was significantly influenced by gender, household income, permanent labour, cultivated area, tenure certainty, irrigable land size and crop diversification. On the other hand, age, permanent labour, irrigable land size and crop diversification significantly influenced farmers’ decisions to rent-out land. The conclusion was that household characteristics, land endowments and transaction costs significantly influenced the decision to rent-in land while the former two were strong in influencing renting-out decisions. Results from the linearized Cobb Douglas model showed that economic efficiency for most farmers was above 50%. Farmers renting-out land under A1 were found to be the most economically efficient, followed by those who were renting-in and least efficient were farmers not participating in land rental markets, though the differences were marginal. For the A2 model, renting-in farmers were the most efficient, followed by those in autarky position, while renting-out farmers were the least. Overall, the most efficient farmers were those renting-in, followed by those renting-out while farmers in autarky were the least efficient. Overall efficiency was higher for A2 farmers than for A1 farmers. For farmers not participating in rental markets, the sources of inefficiency were crop type, crop area and labour. For farmers renting-in, it was proportion of irrigable land, size of irrigable land, crop type, crop area and viii labour, while inefficiency drivers for renting-out farmers were crop type and associated area. Equity analysis showed that participation in land rental markets reduced inequality for farmers in the two districts and male and female headed households. Inequality was increased among A1 farmers and remained unchanged among A2 farmers. Overall, the emerging position was that participation in land rental markets resulted in higher efficiency and reduced inequality in land holding among the sampled farmers. It is recommended that government should be consistent on land rental policy and bring into place effective administration of land rental policy. Government may also consider formal acceptance of land rental markets in light of the marginal efficiency and equity benefits shown in the study. However, formalizing land rental markets alone may not be a panacea to improved efficiency and needs to be supported by other productivity measures given the average efficiency values for farmers. Crop and livestock production based on compatibility with the natural regions and defined minimum size of land should be encouraged to improve efficiency
- Full Text:
- Date Issued: 2019
The contribution of the citrus sub-sector to the economy of Sundays River Valley Local Municipality
- Authors: Smith, Siphelele Ricardo
- Date: 2019
- Language: English
- Type: Thesis , Masters , M Agric (Agric Extension)
- Identifier: http://hdl.handle.net/10353/18861 , vital:42878
- Description: Neither the South African government, nor organised agriculture, nor the research community, has an accurate understanding of the role that the citrus sub-sector plays in the local economy of the main producing areas. There are in fact few studies in South Africa on the linkages between agriculture and other economic sectors at the local level. Through understanding the backward and forward linkages in the citrus sub-sector in Sundays River Valley, one of South Africa’s main citrus areas, it is possible to obtain a better understanding of how investment and expenditure in this sub-sector might influence other related subsectors. The main objective of the study is to assess and understand the citrus industry's contribution to the local economy of Sundays River Valley Local Municipality. This is done through the estimation of an input-output table which differentiates local from non-local economic linkages, and which also, given the labour intensity of the citrus subsector, is closed with respect to households, i.e. households are treated as an endogenous sector with interrelationships with the other sectors captured. The other sectors captured include agroprocessing, utilities, transport and retail. The input-out table, which is estimated based on primary surveys as well as secondary data, is thereafter used to perform input-output analysis on the basis of which the impact of different types of sectoral development are simulated. Results show that jobs can be created through expansion of area under citrus. In addition, more income to farm workers translates into higher income into the local retail sector. However, labour-saving technology could lead to job losses in both citrus and agroprocessing sectors.
- Full Text:
- Date Issued: 2019
- Authors: Smith, Siphelele Ricardo
- Date: 2019
- Language: English
- Type: Thesis , Masters , M Agric (Agric Extension)
- Identifier: http://hdl.handle.net/10353/18861 , vital:42878
- Description: Neither the South African government, nor organised agriculture, nor the research community, has an accurate understanding of the role that the citrus sub-sector plays in the local economy of the main producing areas. There are in fact few studies in South Africa on the linkages between agriculture and other economic sectors at the local level. Through understanding the backward and forward linkages in the citrus sub-sector in Sundays River Valley, one of South Africa’s main citrus areas, it is possible to obtain a better understanding of how investment and expenditure in this sub-sector might influence other related subsectors. The main objective of the study is to assess and understand the citrus industry's contribution to the local economy of Sundays River Valley Local Municipality. This is done through the estimation of an input-output table which differentiates local from non-local economic linkages, and which also, given the labour intensity of the citrus subsector, is closed with respect to households, i.e. households are treated as an endogenous sector with interrelationships with the other sectors captured. The other sectors captured include agroprocessing, utilities, transport and retail. The input-out table, which is estimated based on primary surveys as well as secondary data, is thereafter used to perform input-output analysis on the basis of which the impact of different types of sectoral development are simulated. Results show that jobs can be created through expansion of area under citrus. In addition, more income to farm workers translates into higher income into the local retail sector. However, labour-saving technology could lead to job losses in both citrus and agroprocessing sectors.
- Full Text:
- Date Issued: 2019
Isolation and characterization of E. coli and Campylobacter spp. from diarrhoeal samples collected from selected hospitals in Amathole District Municipality, Eastern Cape, South Africa
- Authors: Omolajaiye, Sunday Abraham
- Date: 2018
- Subjects: Escherichia coli infections Campylobacter infections Diarrhea
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6213 , vital:29515
- Description: Approximately 2-4 billion cases of infectious diarrhoea occur every year, with the highest numbers recorded in sub-Saharan Africa. It remains the most common public health issue among children in developing nations. The purpose of this research was to unfold the prevalence of diarrhoeagenic E. coli and Campylobacter pathotypes as well as elucidate their antibiogram characteristics in diarrhoeal stool samples collected in some medical facilities in Eastern Cape Province, South Africa. Two hundred stool samples were collected from both inpatients and outpatients from male and females of all age groups attending selected medical facilities in the study area. Isolation and characterization of both organisms were done using culture based and molecular methods. Antibiotic susceptibility patterns of identified isolates were determined against a panel of 12 antimicrobial agents. One hundred and twenty presumptive E. coli isolates and 42 presumptive isolates of Campylobacter spp. Were isolated. Eighty-two percent (82 percent) of the presumptive E. coli isolates were confirmed as E. coli while 46.3 percent belonged to Campylobacter spp. Pathotyping of the diarrhoeagenic E. coli isolates by Polymerase chain reaction (PCR) showed the following prevalences: DAEC 43 (32 percent), EHEC 18 (17 percent), EIEC 11 (10 percent) and EPEC 18 (17 percent). EAEC and ETEC were not detected, while for Campylobacter spp. 37 (88 percent) were C. jejuni, and C. coli was not detected. A total of 12 (32.4 percent) of the confirmed Campylobacter jejuni isolates were found to possess the fliM gene, 9 (24.3 percent) possessed the flhA gene and only 6 (16.2 percent) harboured the gene flgE2. None were positive for the flaA, flab and flhB genes.The antibiotic resistance patterns observed among the E. coli isolates were high against ampicillin (98.1 percent), chloramphenicol (94.3 percent) and tetracycline (90.6 percent). For Campylobacter spp., resistance observed were: chloramphenicol (91.6 percent), tetracycline (25.2 percent), erythromycin (49.6 percent) and gentamycin (56.4 percent). A lesser resistance against imipenem (35.9 percent) and quinolone (ciprofloxacin) (45.5 percent) were exhibited by the E.coli isolates. 10.8 percent and 20.3 percent of the Campylobacter isolates were resistant to imipenem and ciprofloxacin respectively. The presence of chloramphenicol (CatA1) and tetracycline (tetA) resistance genes were detected in 94 percent and 89 percent of E. coli isolates respectively while 98 percent of Campylobacter spp. Harboured the catA1 resistance gene. It could be deduced from this study that E. coli and Campylobacter spp. are predomiant enteric pathogens as the etiologic agents of diarrhoea in the study community, and that their antimicrobial resistance is high in the study location. The need to develop strategies to prevent infection and control resistant organisms is evident.
- Full Text:
- Date Issued: 2018
- Authors: Omolajaiye, Sunday Abraham
- Date: 2018
- Subjects: Escherichia coli infections Campylobacter infections Diarrhea
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6213 , vital:29515
- Description: Approximately 2-4 billion cases of infectious diarrhoea occur every year, with the highest numbers recorded in sub-Saharan Africa. It remains the most common public health issue among children in developing nations. The purpose of this research was to unfold the prevalence of diarrhoeagenic E. coli and Campylobacter pathotypes as well as elucidate their antibiogram characteristics in diarrhoeal stool samples collected in some medical facilities in Eastern Cape Province, South Africa. Two hundred stool samples were collected from both inpatients and outpatients from male and females of all age groups attending selected medical facilities in the study area. Isolation and characterization of both organisms were done using culture based and molecular methods. Antibiotic susceptibility patterns of identified isolates were determined against a panel of 12 antimicrobial agents. One hundred and twenty presumptive E. coli isolates and 42 presumptive isolates of Campylobacter spp. Were isolated. Eighty-two percent (82 percent) of the presumptive E. coli isolates were confirmed as E. coli while 46.3 percent belonged to Campylobacter spp. Pathotyping of the diarrhoeagenic E. coli isolates by Polymerase chain reaction (PCR) showed the following prevalences: DAEC 43 (32 percent), EHEC 18 (17 percent), EIEC 11 (10 percent) and EPEC 18 (17 percent). EAEC and ETEC were not detected, while for Campylobacter spp. 37 (88 percent) were C. jejuni, and C. coli was not detected. A total of 12 (32.4 percent) of the confirmed Campylobacter jejuni isolates were found to possess the fliM gene, 9 (24.3 percent) possessed the flhA gene and only 6 (16.2 percent) harboured the gene flgE2. None were positive for the flaA, flab and flhB genes.The antibiotic resistance patterns observed among the E. coli isolates were high against ampicillin (98.1 percent), chloramphenicol (94.3 percent) and tetracycline (90.6 percent). For Campylobacter spp., resistance observed were: chloramphenicol (91.6 percent), tetracycline (25.2 percent), erythromycin (49.6 percent) and gentamycin (56.4 percent). A lesser resistance against imipenem (35.9 percent) and quinolone (ciprofloxacin) (45.5 percent) were exhibited by the E.coli isolates. 10.8 percent and 20.3 percent of the Campylobacter isolates were resistant to imipenem and ciprofloxacin respectively. The presence of chloramphenicol (CatA1) and tetracycline (tetA) resistance genes were detected in 94 percent and 89 percent of E. coli isolates respectively while 98 percent of Campylobacter spp. Harboured the catA1 resistance gene. It could be deduced from this study that E. coli and Campylobacter spp. are predomiant enteric pathogens as the etiologic agents of diarrhoea in the study community, and that their antimicrobial resistance is high in the study location. The need to develop strategies to prevent infection and control resistant organisms is evident.
- Full Text:
- Date Issued: 2018
Barriers and reasons for exercise of rural and urban overweight and obese populations in Buffalo City Metropolitan Municipality, Eastern Cape
- Authors: Mrwebi, Thembani
- Date: 2021-04
- Subjects: Obesity--Prevention , Public health--Exercise
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22522 , vital:52388
- Description: It is documented that obesity is highly prevalent across rural and urban groups in industrialised and underdeveloped countries. This problem is an alarming issue as community members remain unsure about avoiding risking their health. Various health surveys reveal that obesity has increased among communities in the Buffalo City Metro Municipality in the Eastern Cape, and it has consequently made communities vulnerable to non-communicable diseases. The researcher explored factors and barriers of exercise for rural and urban obese populations in Buffalo City Metropolitan Municipality, Eastern Cape. This study was descriptive and explorative, utilising a questionnaire for gathering information. A purposive sample of 80 members from the two selected communities completed the questionnaire. A factor analysis was performed to identify factors that motivate physical activity and barriers to physical activity. It was discovered that all evaluated members were fully aware of the harmful repercussions of being overweight or obese. Nevertheless, only a tiny percentage of those who took part in the study decided to live a healthier lifestyle because of their obesity. Constructive motivating factors included increasing their self-image, enhancing their wellbeing, and getting highly involved in active and regular exercise. Negative motivators included finding it challenging to fit into old clothes and the worry of developing obesity-related diseases. Respondents noted the following impediments in regular exercises and physical activities; African cultural values, limited operational hours of physical activity facilities, insufficient time, and a lack of enthusiasm. , Thesis (MPhil) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mrwebi, Thembani
- Date: 2021-04
- Subjects: Obesity--Prevention , Public health--Exercise
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22522 , vital:52388
- Description: It is documented that obesity is highly prevalent across rural and urban groups in industrialised and underdeveloped countries. This problem is an alarming issue as community members remain unsure about avoiding risking their health. Various health surveys reveal that obesity has increased among communities in the Buffalo City Metro Municipality in the Eastern Cape, and it has consequently made communities vulnerable to non-communicable diseases. The researcher explored factors and barriers of exercise for rural and urban obese populations in Buffalo City Metropolitan Municipality, Eastern Cape. This study was descriptive and explorative, utilising a questionnaire for gathering information. A purposive sample of 80 members from the two selected communities completed the questionnaire. A factor analysis was performed to identify factors that motivate physical activity and barriers to physical activity. It was discovered that all evaluated members were fully aware of the harmful repercussions of being overweight or obese. Nevertheless, only a tiny percentage of those who took part in the study decided to live a healthier lifestyle because of their obesity. Constructive motivating factors included increasing their self-image, enhancing their wellbeing, and getting highly involved in active and regular exercise. Negative motivators included finding it challenging to fit into old clothes and the worry of developing obesity-related diseases. Respondents noted the following impediments in regular exercises and physical activities; African cultural values, limited operational hours of physical activity facilities, insufficient time, and a lack of enthusiasm. , Thesis (MPhil) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-04
Modelling false positive reduction in maritime object detection
- Authors: Nkele, Nosiphiwo
- Date: 20xx
- Subjects: Computer vision Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc (Computer Science )
- Identifier: http://hdl.handle.net/10353/17168 , vital:40862
- Description: Target detection has become a very significant research area in computer vision with its applications in military, maritime surveillance, and defense and security. Maritime target detection during critical sea conditions produces a number of false positives when using the existing algorithms due to sea waves, dynamic nature of the ocean, camera motion, sea glint, sensor noise, sea spray, swell and the presence of birds. The main question that has been addressed in this research is how can object detection be improved in maritime environment by reducing false positives and promoting detection rate. Most of Previous work on object detection still fails to address the problem of false positives and false negatives due to background clutter. Most of the researchers tried to reduce false positives by applying filters but filtering degrades the quality of an image leading to more false alarms during detection. As much as radar technology has previously been the most utilized method, it still fails to detect very small objects and it may be applied in special circumstances. In trying to improve the implementation of target detection in maritime, empirical research method was proposed to answer questions about existing target detection algorithms and techniques used to reduce false positives in object detection. Visible images were retrained on a pre-trained Faster R-CNN with inception v2. The pre-trained model was retrained on five different sample data with increasing size, however for the last two samples the data was duplicated to increase size. For testing purposes 20 test images were utilized to evaluate all the models. The results of this study showed that the deep learning method used performed best in detecting maritime vessels and the increase of dataset improved detection performance and false positives were reduced. The duplication of images did not yield the best results; however, the results were promising for the first three models with increasing data.
- Full Text:
- Date Issued: 20xx
- Authors: Nkele, Nosiphiwo
- Date: 20xx
- Subjects: Computer vision Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc (Computer Science )
- Identifier: http://hdl.handle.net/10353/17168 , vital:40862
- Description: Target detection has become a very significant research area in computer vision with its applications in military, maritime surveillance, and defense and security. Maritime target detection during critical sea conditions produces a number of false positives when using the existing algorithms due to sea waves, dynamic nature of the ocean, camera motion, sea glint, sensor noise, sea spray, swell and the presence of birds. The main question that has been addressed in this research is how can object detection be improved in maritime environment by reducing false positives and promoting detection rate. Most of Previous work on object detection still fails to address the problem of false positives and false negatives due to background clutter. Most of the researchers tried to reduce false positives by applying filters but filtering degrades the quality of an image leading to more false alarms during detection. As much as radar technology has previously been the most utilized method, it still fails to detect very small objects and it may be applied in special circumstances. In trying to improve the implementation of target detection in maritime, empirical research method was proposed to answer questions about existing target detection algorithms and techniques used to reduce false positives in object detection. Visible images were retrained on a pre-trained Faster R-CNN with inception v2. The pre-trained model was retrained on five different sample data with increasing size, however for the last two samples the data was duplicated to increase size. For testing purposes 20 test images were utilized to evaluate all the models. The results of this study showed that the deep learning method used performed best in detecting maritime vessels and the increase of dataset improved detection performance and false positives were reduced. The duplication of images did not yield the best results; however, the results were promising for the first three models with increasing data.
- Full Text:
- Date Issued: 20xx