Involving fishermen in seabirds’ conservation: bridging the gap between socio-economic needs of industry and the needs of seabirds
- Authors: Ginsburg, Tayla
- Date: 2019
- Subjects: Sea birds -- Ecology , Island ecology Island animals -- Conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42184 , vital:36633
- Description: Marine ecosystems and species face multiple threats, particularly intensive industrial-scale fishing activities. As the human population continues to increase exponentially and drive a greater demand for food, commercial fishing effort will likely intensify. While terrestrial protected areas are well developed, marine protected areas (MPAs) are less so, both in the area covered and management practices. There is currently a drive to increase the extent of MPAs, both globally and in South Africa, particularly for those ecosystems and marine species that can benefit from area-based management. The size, shape, location zonation of MPAs generally remain static through time. However, the ocean is a dynamic environment and static MPAs are not always able to achieve conservation objectives for their component ecosystems and species. Dynamic Ocean Management (DOM) is an approach that integrates near real-time data on biological, oceanographic, social and/or economic variables to adjust an MPAs boundary and zonation in both space and time. The aim of this thesis was to assess the viability of applying DOM to a fishing exclusion zone within a zoned MPA in Algoa Bay, South Africa, to support conservation objectives for the Endangered African penguin Spheniscus demersus. Algoa Bay supports half of the world’s remaining population of this species. First, the degree of spatial overlap between foraging penguins and purse-seine fishers in Algoa Bay was determined over five years. In all years, purse-seiner fishing vessels were located around or near to St Croix Island and a large proportion of the total pelagic fish catch from the Bay was removed from this area. Breeding penguins travelled significantly further while foraging when the overlap (and subsequent competition for pelagic fish) was higher, suggesting that African penguins would benefit from a fishing exclusion zone around St Croix Island owing to reduced competition. However, an exclusion zone can have socio-economic impacts on fisheries as a result of the lost fishing area. A common concern raised by fishers is the direct loss of income, either as a result of increased fuel costs to reach alternate fishing grounds or decreased catch. An analysis of catch and travel time (as a proxy for fuel costs) when a 20 km exclusion zone was present or absent around St Croix Island revealed that the exclusion zone scenarios had no significant impact on either variable. Interviews with individuals in the local purse-seine fishery (both fishers and factory managers) showed a consensus that the marine environment needs protection and that MPAs have various environmental benefits. Despite this, individuals were concerned about how they would be impacted by the exclusion zone in the MPA. The interviews highlighted the willingness of individuals in the purse-seine fishery to talk to and work with scientists.
- Full Text:
- Date Issued: 2019
- Authors: Ginsburg, Tayla
- Date: 2019
- Subjects: Sea birds -- Ecology , Island ecology Island animals -- Conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42184 , vital:36633
- Description: Marine ecosystems and species face multiple threats, particularly intensive industrial-scale fishing activities. As the human population continues to increase exponentially and drive a greater demand for food, commercial fishing effort will likely intensify. While terrestrial protected areas are well developed, marine protected areas (MPAs) are less so, both in the area covered and management practices. There is currently a drive to increase the extent of MPAs, both globally and in South Africa, particularly for those ecosystems and marine species that can benefit from area-based management. The size, shape, location zonation of MPAs generally remain static through time. However, the ocean is a dynamic environment and static MPAs are not always able to achieve conservation objectives for their component ecosystems and species. Dynamic Ocean Management (DOM) is an approach that integrates near real-time data on biological, oceanographic, social and/or economic variables to adjust an MPAs boundary and zonation in both space and time. The aim of this thesis was to assess the viability of applying DOM to a fishing exclusion zone within a zoned MPA in Algoa Bay, South Africa, to support conservation objectives for the Endangered African penguin Spheniscus demersus. Algoa Bay supports half of the world’s remaining population of this species. First, the degree of spatial overlap between foraging penguins and purse-seine fishers in Algoa Bay was determined over five years. In all years, purse-seiner fishing vessels were located around or near to St Croix Island and a large proportion of the total pelagic fish catch from the Bay was removed from this area. Breeding penguins travelled significantly further while foraging when the overlap (and subsequent competition for pelagic fish) was higher, suggesting that African penguins would benefit from a fishing exclusion zone around St Croix Island owing to reduced competition. However, an exclusion zone can have socio-economic impacts on fisheries as a result of the lost fishing area. A common concern raised by fishers is the direct loss of income, either as a result of increased fuel costs to reach alternate fishing grounds or decreased catch. An analysis of catch and travel time (as a proxy for fuel costs) when a 20 km exclusion zone was present or absent around St Croix Island revealed that the exclusion zone scenarios had no significant impact on either variable. Interviews with individuals in the local purse-seine fishery (both fishers and factory managers) showed a consensus that the marine environment needs protection and that MPAs have various environmental benefits. Despite this, individuals were concerned about how they would be impacted by the exclusion zone in the MPA. The interviews highlighted the willingness of individuals in the purse-seine fishery to talk to and work with scientists.
- Full Text:
- Date Issued: 2019
Statistical optimisation of a terbinafine-containing cream
- Authors: Strydom, Lana
- Date: 2019
- Subjects: Chemicals -- Physiological effect , Pharmaceutical chemistry Medical microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44067 , vital:37101
- Description: Terbinafine hydrochloride (TBH) belongs to the allylamine class of antifungals and displays a favourable dermatopharmacokinetic profile, being both lipophilic and keratinophilic. It has thus been included in a variety of topical dosage forms for the treatment of dermatomycoses, many of which have been the subject of optimisation studies, with the purpose of improving the product. Since a TBH-containing cream had not been found in literature to have been optimised before, the aim of this study was to optimise a TBH cream formulation. A TBH cream formulation, suitable for optimisation, was developed. Preformulation tests were undertaken, including active-excipient compatibility testing using a combined thermal method consisting of both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), as well as isothermal stress testing (IST). With the confirmation of the suitability of the selected excipients, development of a suitable TBH cream took place largely by a trial-and-error approach. The choice of a suitable formulation was made based on the physical appearance and viscosity of the cream, for which a viscosity specification was set. The identified TBH cream formulation was evaluated for its physical appearance and physicochemical aspects to confirm its appropriateness for the purpose of further optimisation. Based on literature and observations from the preformulation and formulation stage, factors and responses for study during the optimisation stage were identified to study using a circumscribed central composite design (CCCD) at five levels (-1.612, -1, 0, +1, +1.612). Total percentage of surfactant (TPS), homogenisation speed (HS) and cooling rate (CR), were selected as factors to study their influence on cream viscosity, in vitro TBH release from the cream, as well as the chemical stability of TBH within the cream formulation. Following the application of stepwise multiple linear regression to the mathematical models, a suitable prediction model was only obtained for one response, cream viscosity at a shear rate of 20 s-1. A linear model was also found to fit the data for % in vitro TBH release after one hour, although a low R2 of 0.497 made the model unsuitable for prediction purposes. No mathematical model could be fit to the results for the response assessing the change in TBH concentration following seven days’ storage at accelerated stability conditions. The determination of the optimum TBH cream formulation was made chiefly on the basis of the results for cream viscosity and the optimised formulation was identified to have a predicted viscosity of 8.33 Pa.s and the factor settings to obtain this cream were a CR of 1.3 °C/min, HS set at 3400 rpm, and TPS of 4.2 %. Validation of the optimised TBH cream formulation was performed for cream viscosity at a shear rate of 20 s-1 and revealed that there was good agreement between the measured and predicted viscosity values. The optimised TBH cream underwent rheological characterisation and was compared to the innovator, Lamisil® cream, with both creams found to meet the desirable rheological profile. In vitro release testing (IVRT) was used to compare the release of TBH from the optimised TBH cream and Lamisil® cream, and the optimised TBH cream was found to show much greater TBH release over a six-hour time period than Lamisil® cream. Stability testing of the optimised TBH cream took place at accelerated stability testing conditions of 40 °C ± 2 °C and 75 ± 5 % relative humidity (RH). To assay the formulation and determine content uniformity over the three-month storage period, a suitable stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method was developed and validated. Other cream properties which were tested included: qualitative aspects, viscosity, pH and microbial limits. At the end of the three-month stability testing period, the cream was found to meet most of the specifications set, except for cream homogeneity and viscosity. A TBH cream formulation was thus developed and optimised to meet a certain viscosity specification. Although this formulation was found to meet the viscosity specification on the day after its manufacture, the viscosity was found to increase on storage, such that it was outside the set viscosity specification range.
- Full Text:
- Date Issued: 2019
- Authors: Strydom, Lana
- Date: 2019
- Subjects: Chemicals -- Physiological effect , Pharmaceutical chemistry Medical microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44067 , vital:37101
- Description: Terbinafine hydrochloride (TBH) belongs to the allylamine class of antifungals and displays a favourable dermatopharmacokinetic profile, being both lipophilic and keratinophilic. It has thus been included in a variety of topical dosage forms for the treatment of dermatomycoses, many of which have been the subject of optimisation studies, with the purpose of improving the product. Since a TBH-containing cream had not been found in literature to have been optimised before, the aim of this study was to optimise a TBH cream formulation. A TBH cream formulation, suitable for optimisation, was developed. Preformulation tests were undertaken, including active-excipient compatibility testing using a combined thermal method consisting of both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), as well as isothermal stress testing (IST). With the confirmation of the suitability of the selected excipients, development of a suitable TBH cream took place largely by a trial-and-error approach. The choice of a suitable formulation was made based on the physical appearance and viscosity of the cream, for which a viscosity specification was set. The identified TBH cream formulation was evaluated for its physical appearance and physicochemical aspects to confirm its appropriateness for the purpose of further optimisation. Based on literature and observations from the preformulation and formulation stage, factors and responses for study during the optimisation stage were identified to study using a circumscribed central composite design (CCCD) at five levels (-1.612, -1, 0, +1, +1.612). Total percentage of surfactant (TPS), homogenisation speed (HS) and cooling rate (CR), were selected as factors to study their influence on cream viscosity, in vitro TBH release from the cream, as well as the chemical stability of TBH within the cream formulation. Following the application of stepwise multiple linear regression to the mathematical models, a suitable prediction model was only obtained for one response, cream viscosity at a shear rate of 20 s-1. A linear model was also found to fit the data for % in vitro TBH release after one hour, although a low R2 of 0.497 made the model unsuitable for prediction purposes. No mathematical model could be fit to the results for the response assessing the change in TBH concentration following seven days’ storage at accelerated stability conditions. The determination of the optimum TBH cream formulation was made chiefly on the basis of the results for cream viscosity and the optimised formulation was identified to have a predicted viscosity of 8.33 Pa.s and the factor settings to obtain this cream were a CR of 1.3 °C/min, HS set at 3400 rpm, and TPS of 4.2 %. Validation of the optimised TBH cream formulation was performed for cream viscosity at a shear rate of 20 s-1 and revealed that there was good agreement between the measured and predicted viscosity values. The optimised TBH cream underwent rheological characterisation and was compared to the innovator, Lamisil® cream, with both creams found to meet the desirable rheological profile. In vitro release testing (IVRT) was used to compare the release of TBH from the optimised TBH cream and Lamisil® cream, and the optimised TBH cream was found to show much greater TBH release over a six-hour time period than Lamisil® cream. Stability testing of the optimised TBH cream took place at accelerated stability testing conditions of 40 °C ± 2 °C and 75 ± 5 % relative humidity (RH). To assay the formulation and determine content uniformity over the three-month storage period, a suitable stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method was developed and validated. Other cream properties which were tested included: qualitative aspects, viscosity, pH and microbial limits. At the end of the three-month stability testing period, the cream was found to meet most of the specifications set, except for cream homogeneity and viscosity. A TBH cream formulation was thus developed and optimised to meet a certain viscosity specification. Although this formulation was found to meet the viscosity specification on the day after its manufacture, the viscosity was found to increase on storage, such that it was outside the set viscosity specification range.
- Full Text:
- Date Issued: 2019
Foreground simulations for observations of the global 21-cm signal
- Authors: Klutse, Diana
- Date: 2019
- Subjects: Cosmic background radiation , Astronomy -- Observations , Electromagnetic waves , Radiation, Background
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76398 , vital:30557
- Description: The sky-averaged (global) spectrum of the redshifted 21-cm line promises to be a direct probe of the Dark Ages, the period before the first luminous sources formed and the Epoch of Reionization during which these sources produced enough ionizing photons to ionize the neutral intergalactic medium. However, observations of this signal are contaminated by both astrophysical foregrounds which are orders of magnitude brighter than the cosmological signal and by non-astrophysical and non-ideal instrumental effects. It is therefore crucial to understand all these data components and their impacts on the cosmological signal, for successful signal extraction. In this view, we investigated the impact that small scale spatial structures of diffuse Galactic foreground has on the foreground spectrum as observed by a global 21-cm observation. We simulated two different sets of observations using a realistic dipole beam model of two synchotron foreground templates that differ from each other in the small scale structure: the original 408 MHz all-sky map by Haslam et al. (1982) and a version where the calibration was improved to remove artifcats and point sources (Remazeilles et al., 2015). We generated simulated foreground spectra and modeled them using a polynomial expansion in frequency. We found that the different foreground templates have a modest impact on the simulated spectra, generate differences up to 2% in the root mean square of residual spectra after the log-polynomial best fit was subtracted out.
- Full Text:
- Date Issued: 2019
- Authors: Klutse, Diana
- Date: 2019
- Subjects: Cosmic background radiation , Astronomy -- Observations , Electromagnetic waves , Radiation, Background
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76398 , vital:30557
- Description: The sky-averaged (global) spectrum of the redshifted 21-cm line promises to be a direct probe of the Dark Ages, the period before the first luminous sources formed and the Epoch of Reionization during which these sources produced enough ionizing photons to ionize the neutral intergalactic medium. However, observations of this signal are contaminated by both astrophysical foregrounds which are orders of magnitude brighter than the cosmological signal and by non-astrophysical and non-ideal instrumental effects. It is therefore crucial to understand all these data components and their impacts on the cosmological signal, for successful signal extraction. In this view, we investigated the impact that small scale spatial structures of diffuse Galactic foreground has on the foreground spectrum as observed by a global 21-cm observation. We simulated two different sets of observations using a realistic dipole beam model of two synchotron foreground templates that differ from each other in the small scale structure: the original 408 MHz all-sky map by Haslam et al. (1982) and a version where the calibration was improved to remove artifcats and point sources (Remazeilles et al., 2015). We generated simulated foreground spectra and modeled them using a polynomial expansion in frequency. We found that the different foreground templates have a modest impact on the simulated spectra, generate differences up to 2% in the root mean square of residual spectra after the log-polynomial best fit was subtracted out.
- Full Text:
- Date Issued: 2019
Devulcanisation of truck tyre tread vulcanisates in supercritical carbon dioxide using diphenyl disulphide and 2,2- dithiobis(benzothiazole)
- Mabuto, Briswell, Ogunlanja, A
- Authors: Mabuto, Briswell , Ogunlanja, A
- Date: 2019
- Subjects: Vulcanization , Polymeric composites Rubber Carbon dioxide -- Thermal properties Environmental chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40702 , vital:36224
- Description: A lot of work has been done in the recycling industry in an effort to increase the amount of reclaimed rubber used in new tyre formulations. The major drawback has been inferior physical and mechanical properties of reclaimed/virgin rubber blends in comparison to the virgin rubber material. Deterioration in these properties has been identified to be a result of chain degradation during reclamation processes as well as presence of crosslinks in the final reclaim product. Devulcanisation techniques have gained precedence due to the relatively improved properties of devulcanised/virgin rubber blends. The concept of devulcanisation is to reverse vulcanisation, resulting in total or partial cleavage of crosslinks. In this way, chain degradation is minimised while crosslink scission is maximised, thereby resulting in good quality devulcanised rubber. However, due to the persistence of chain degradation and crosslinks during devulcanisation processes, a very limited number of reports have claimed success in achieving this goal. Therefore there is still the need to develop a devulcanisation method that ensures improved quality and productivity of devulcanised rubber. Typical truck tyre tread vulcanisates were used for optimisation of time, temperature, heating rate, pressure and amount of devulcanising agent while monitoring percentage devulcanisation in supercritical carbon dioxide medium. Optimisation of the devulcanisation conditions was done by employing a twolevel central composite design in the isothermal and non-isothermal heating stages. This was followed by a single factor analysis of devulcanisation conditions in the non-isothermal stage. The effect of the presence of carbon black was investigated by comparing the percentage devulcanisation of carbon black filled and unfilled samples. The results show that supercritical carbon dioxide is an effective medium of devulcanisation using diphenyl disulphide (DD) and 2,2-dithiobis(benzothiazole) (MBTS). The relatively higher degree of devulcanisation observed during the non-isothermal stage compared to the isothermal stage, led to a shift of focus to non-isothermal devulcanisation. Temperature and time were found to have a significant antagonistic effect on the percentage devulcanisation, while changes in pressure above critical point and mass of devulcanising agent showed no effect on percentage devulcanisation. The heating rate was determined by the set-point, of which 180 ℃ set-point temperature resulted in desirable degree of devulcanisation for both DD and MBTS. 76.18 ± 5.50 % devulcanisation in 5 minutes at 102 ℃ was observed for DD whilst 70.92 ± 4.10 % devulcanisation in 4 minutes at 97 ℃ was observed for MBTS. Changes in pressure above critical point and mass of devulcanising agent used in devulcanisation showed no significant effect in the percentage devulcanisation and so they were kept constant at 80 bars and 1.00 % v (of weight of rubber sample) devulcanisation agent, respectively. The presence of carbon black was found to have an effect on the degree of devulcanisation; 87.95 % and 81.33 % devulcanisation was observed for unfilled samples devulcanised using DD and MBTS respectively. Thermogravimetric analysis of the natural rubber/styrene butadiene rubber (NR/SBR respectively) relative composition of devulcanisates indicated uneven devulcanisation when using DD, whereas MBTS did not show any form of preference. DD showed preference for NR devulcanisation over SBR. Further analysis of the sol and gel fractions were performed using; Differential Scanning Calorimetry, Fourier Transform Infrared Spectroscopy, Gel Permeation Chromatography and Gas Chromatography coupled with Mass Spectroscopy. Application of the optimised conditions to devulcanise ground tyre rubber (GTR) resulted in relatively lower degrees of devulcanisation for both DD and MBTS; 41.22 ± 4.22 and 22.41 ± 1.97 respectively. The differences in the degree of devulcanisation of the laboratory prepared vulcanisates and the GTR was determined to be due to sample differences; i.e. sample constituents, particle dimensions and crosslink network (crosslink distribution in particular).
- Full Text:
- Date Issued: 2019
- Authors: Mabuto, Briswell , Ogunlanja, A
- Date: 2019
- Subjects: Vulcanization , Polymeric composites Rubber Carbon dioxide -- Thermal properties Environmental chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40702 , vital:36224
- Description: A lot of work has been done in the recycling industry in an effort to increase the amount of reclaimed rubber used in new tyre formulations. The major drawback has been inferior physical and mechanical properties of reclaimed/virgin rubber blends in comparison to the virgin rubber material. Deterioration in these properties has been identified to be a result of chain degradation during reclamation processes as well as presence of crosslinks in the final reclaim product. Devulcanisation techniques have gained precedence due to the relatively improved properties of devulcanised/virgin rubber blends. The concept of devulcanisation is to reverse vulcanisation, resulting in total or partial cleavage of crosslinks. In this way, chain degradation is minimised while crosslink scission is maximised, thereby resulting in good quality devulcanised rubber. However, due to the persistence of chain degradation and crosslinks during devulcanisation processes, a very limited number of reports have claimed success in achieving this goal. Therefore there is still the need to develop a devulcanisation method that ensures improved quality and productivity of devulcanised rubber. Typical truck tyre tread vulcanisates were used for optimisation of time, temperature, heating rate, pressure and amount of devulcanising agent while monitoring percentage devulcanisation in supercritical carbon dioxide medium. Optimisation of the devulcanisation conditions was done by employing a twolevel central composite design in the isothermal and non-isothermal heating stages. This was followed by a single factor analysis of devulcanisation conditions in the non-isothermal stage. The effect of the presence of carbon black was investigated by comparing the percentage devulcanisation of carbon black filled and unfilled samples. The results show that supercritical carbon dioxide is an effective medium of devulcanisation using diphenyl disulphide (DD) and 2,2-dithiobis(benzothiazole) (MBTS). The relatively higher degree of devulcanisation observed during the non-isothermal stage compared to the isothermal stage, led to a shift of focus to non-isothermal devulcanisation. Temperature and time were found to have a significant antagonistic effect on the percentage devulcanisation, while changes in pressure above critical point and mass of devulcanising agent showed no effect on percentage devulcanisation. The heating rate was determined by the set-point, of which 180 ℃ set-point temperature resulted in desirable degree of devulcanisation for both DD and MBTS. 76.18 ± 5.50 % devulcanisation in 5 minutes at 102 ℃ was observed for DD whilst 70.92 ± 4.10 % devulcanisation in 4 minutes at 97 ℃ was observed for MBTS. Changes in pressure above critical point and mass of devulcanising agent used in devulcanisation showed no significant effect in the percentage devulcanisation and so they were kept constant at 80 bars and 1.00 % v (of weight of rubber sample) devulcanisation agent, respectively. The presence of carbon black was found to have an effect on the degree of devulcanisation; 87.95 % and 81.33 % devulcanisation was observed for unfilled samples devulcanised using DD and MBTS respectively. Thermogravimetric analysis of the natural rubber/styrene butadiene rubber (NR/SBR respectively) relative composition of devulcanisates indicated uneven devulcanisation when using DD, whereas MBTS did not show any form of preference. DD showed preference for NR devulcanisation over SBR. Further analysis of the sol and gel fractions were performed using; Differential Scanning Calorimetry, Fourier Transform Infrared Spectroscopy, Gel Permeation Chromatography and Gas Chromatography coupled with Mass Spectroscopy. Application of the optimised conditions to devulcanise ground tyre rubber (GTR) resulted in relatively lower degrees of devulcanisation for both DD and MBTS; 41.22 ± 4.22 and 22.41 ± 1.97 respectively. The differences in the degree of devulcanisation of the laboratory prepared vulcanisates and the GTR was determined to be due to sample differences; i.e. sample constituents, particle dimensions and crosslink network (crosslink distribution in particular).
- Full Text:
- Date Issued: 2019
A nutrition education tool for practical application of the food based dietary guidelines for primary school teachers in Nelson Mandela Bay
- Authors: Joubert, Tayla Kate
- Date: 2019
- Subjects: Nutrition -- Education
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44616 , vital:38152
- Description: Background: The South Africa Food-Based Dietary Guidelines (SAFBDG) was developed to promote better food choices for a healthy lifestyle and are included in the school syllabus. Schools remain viable platforms for nutrition education with teachers playing significant roles, but research has shown that teachers do not necessarily know about the SAFBDG and how to incorporate these into the teaching programme. Aim: The aim of this study was to develop a tool in the form of a nutrition education guide for primary school teachers, aimed at the practical application of the SAFBDG, in order to enhance the nutrition knowledge, attitudes and dietary practices of the teachers. Research design and methodology: A quasi-experimental, one group, quantitative design was employed. Forty-six teachers were conveniently chosen from schools in previously disadvantaged areas of Nelson Mandela Bay. The study design consisted of four phases. Phase one consisted of a pre-test where the teachers’ nutrition knowledge, nutrition attitudes, dietary practices, staff wellness and physical activity were determined by means of a standardised questionnaire. A nutritional assessment was also conducted in phase one. In phase two, the nutrition guide, which was Curriculum Assessment Policy Statement compliant for grades four to seven, was developed. In phase three, the guide was used in a workshop to train the teachers that attended phase one of the study, on how to use the nutrition education guide. In phase four, a post-test was conducted after the training to evaluate the effectiveness of the training and to determine whether there has been an increase in the teachers’ nutrition knowledge. Data from the questionnaires were analysed on Microsoft Excel 2016 MSO (16.0.4639.1000). Ethical approval for this study was obtained from the Faculty Postgraduate Studies Committee (FPGSC) of the Faculty of Health Sciences, Nelson Mandela University (Ethics clearance reference number: H18-HEA-DIET-005) and all ethical principles were upheld according to the Belmont report and the Declaration of Helsinki. Results: Of the 46 teachers who participated 36 (78 %) were obese. The mean waist circumference and waist-to-hip ratio was 109.99 and 0.887 respectively (± 17.32 and ± 0.089). The teachers obtained a relatively high mean overall score in the pre-test of 69 % (± 10.78). Only 42 % of the teachers had heard of the SAFBDG before the study. There was an overall statistical significant increase in knowledge of 6 % (p = 0.03) from the pre-test to the post-test. The dietary practice was obtained through a food frequency questionnaire (FFQ), which showed under-reporting. The most neglected food groups were legumes, dairy and vegetables/ fruit. Hypertension was the highest self-reported condition, with just under a quarter of the teachers having hypertension (high blood pressure). There was no statistical significance between the teachers’ BMI and their nutrition knowledge as well as no statistical significance between their BMI and their physical activity level. Conclusion and recommendations: Even though the teachers obtained a relatively high mean overall score in their pre-test, there were still gaps in their nutrition knowledge. These gaps in the teachers’ knowledge results in insufficient nutrition knowledge being provided to the learners, leading to poor dietary practices and misconceptions regarding different foods among the learners as well as the teachers. By providing training for the teachers, it will not only improve their nutrition knowledge but potentially also help to improve their lifestyle. With enhanced nutrition knowledge, the teachers can communicate sufficient information to their learners. The DoBE need to advocate for a healthier school environment in which the SAFBDG are implemented more extensively in the curriculum as well as part of school food policies.
- Full Text:
- Date Issued: 2019
- Authors: Joubert, Tayla Kate
- Date: 2019
- Subjects: Nutrition -- Education
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44616 , vital:38152
- Description: Background: The South Africa Food-Based Dietary Guidelines (SAFBDG) was developed to promote better food choices for a healthy lifestyle and are included in the school syllabus. Schools remain viable platforms for nutrition education with teachers playing significant roles, but research has shown that teachers do not necessarily know about the SAFBDG and how to incorporate these into the teaching programme. Aim: The aim of this study was to develop a tool in the form of a nutrition education guide for primary school teachers, aimed at the practical application of the SAFBDG, in order to enhance the nutrition knowledge, attitudes and dietary practices of the teachers. Research design and methodology: A quasi-experimental, one group, quantitative design was employed. Forty-six teachers were conveniently chosen from schools in previously disadvantaged areas of Nelson Mandela Bay. The study design consisted of four phases. Phase one consisted of a pre-test where the teachers’ nutrition knowledge, nutrition attitudes, dietary practices, staff wellness and physical activity were determined by means of a standardised questionnaire. A nutritional assessment was also conducted in phase one. In phase two, the nutrition guide, which was Curriculum Assessment Policy Statement compliant for grades four to seven, was developed. In phase three, the guide was used in a workshop to train the teachers that attended phase one of the study, on how to use the nutrition education guide. In phase four, a post-test was conducted after the training to evaluate the effectiveness of the training and to determine whether there has been an increase in the teachers’ nutrition knowledge. Data from the questionnaires were analysed on Microsoft Excel 2016 MSO (16.0.4639.1000). Ethical approval for this study was obtained from the Faculty Postgraduate Studies Committee (FPGSC) of the Faculty of Health Sciences, Nelson Mandela University (Ethics clearance reference number: H18-HEA-DIET-005) and all ethical principles were upheld according to the Belmont report and the Declaration of Helsinki. Results: Of the 46 teachers who participated 36 (78 %) were obese. The mean waist circumference and waist-to-hip ratio was 109.99 and 0.887 respectively (± 17.32 and ± 0.089). The teachers obtained a relatively high mean overall score in the pre-test of 69 % (± 10.78). Only 42 % of the teachers had heard of the SAFBDG before the study. There was an overall statistical significant increase in knowledge of 6 % (p = 0.03) from the pre-test to the post-test. The dietary practice was obtained through a food frequency questionnaire (FFQ), which showed under-reporting. The most neglected food groups were legumes, dairy and vegetables/ fruit. Hypertension was the highest self-reported condition, with just under a quarter of the teachers having hypertension (high blood pressure). There was no statistical significance between the teachers’ BMI and their nutrition knowledge as well as no statistical significance between their BMI and their physical activity level. Conclusion and recommendations: Even though the teachers obtained a relatively high mean overall score in their pre-test, there were still gaps in their nutrition knowledge. These gaps in the teachers’ knowledge results in insufficient nutrition knowledge being provided to the learners, leading to poor dietary practices and misconceptions regarding different foods among the learners as well as the teachers. By providing training for the teachers, it will not only improve their nutrition knowledge but potentially also help to improve their lifestyle. With enhanced nutrition knowledge, the teachers can communicate sufficient information to their learners. The DoBE need to advocate for a healthier school environment in which the SAFBDG are implemented more extensively in the curriculum as well as part of school food policies.
- Full Text:
- Date Issued: 2019
An Integrated Management System to reduce False Codling Moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) infested citrus fruit from being packed for export
- Authors: Mac Aleer, Clint
- Date: 2019
- Subjects: Cryptophlebia leucotreta -- South Africa , Cryptophlebia leucotreta -- Biological control -- South Africa , Citrus -- Diseases and pests -- Biological control -- South Africa , Insect pests -- Biological control -- South Africa , Insecticides , Citrus fruit industry -- South Africa , South Africa -- Commerce -- European Economic Community Countries
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92219 , vital:30691
- Description: False codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is indigenous to southern Africa and is an important pest of citrus in this region. As a result of its endemism to sub-Saharan Africa, several countries to which South Africa exports citrus, regulate it as a phytosanitary pest. Consequently, it is necessary to ship fruit to these markets under cold-disinfestation protocols. This has been possible, as until recently, all of these markets could be considered relatively small niche markets. The South African citrus industry exports approximately 130 million cartons of fruit (15 kg equivalent) annually. During the 2017 season, a total of 48 million cartons were exported to the European Union (EU), which is the equivalent of 41% of South Africa’s total export volume, thus making the EU South Africa’s most important export market. In 2013 the European and Mediterranean Plant Protection Organisation (EPPO) conducted a pest risk analysis (PRA) on FCM, leading to the EU declaring it an officially regulated pest for this region, effective of 1 January 2018. Citrus is regarded as a preferred non-native host of FCM and South African citrus was identified as a primary focus due to large volumes being exported to Europe. Shipping under cold disinfestation is not possible with such large volumes of fruit. Additionally, several cultivars would suffer high levels of chilling injury under such conditions. In this study, an Integrated Management System was tested with pre- and postharvest controls to test the hypothesis that pre-harvest interventions resulted in lower post-harvest infection. Thirty orchards ranging from soft citrus cultivars such as Nule and Nova Mandarins, to Navel orange cultivars such as Newhall, Palmer and Late Navel and ending with Valencia cultivars such as Midknight and Delta, were identified for this study. This system relies on pre-harvest inspections such as FCM trap counts and fruit infestation on data trees in every orchard, with associated thresholds for action or continued compliance. Inspections were conducted on a weekly basis. There was a significant relationship between the moth catches and FCM infestation for the full monitoring period, using a two-week lag period for infestation. Inspections of harvested fruit were conducted at the packhouse to determine FCM infestation. This included inspection of the fruit on delivery to the packhouse, on the packing line, and a final fruit sample taken from the packed product and inspected for FCM. The highest levels of infestation were recorded on the Navel cultivars, thus confirming that Navels cultivars are a preferred host for FCM. Significant positive relationships were recorded between FCM infestation during the last 4 weeks before harvest and the level of infestation in the fruit delivered to the packhouse and between the fruit delivered to the packhouse and in the fruit packed in a carton for export. There was a substantial reduction in infestation between the fruit delivered to the packhouse and the fruit packed in a carton for export, with certain orchards recording as much as a 93% reduction in the fruit packed in a carton, which indicated that the packhouse could effectively identify and remove FCM infested fruit. The outcome of the study is that a holistic management approach minimizes the risk of FCM in citrus fruit destined for export and therefore mitigate the risk associated with FCM.
- Full Text:
- Date Issued: 2019
- Authors: Mac Aleer, Clint
- Date: 2019
- Subjects: Cryptophlebia leucotreta -- South Africa , Cryptophlebia leucotreta -- Biological control -- South Africa , Citrus -- Diseases and pests -- Biological control -- South Africa , Insect pests -- Biological control -- South Africa , Insecticides , Citrus fruit industry -- South Africa , South Africa -- Commerce -- European Economic Community Countries
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92219 , vital:30691
- Description: False codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is indigenous to southern Africa and is an important pest of citrus in this region. As a result of its endemism to sub-Saharan Africa, several countries to which South Africa exports citrus, regulate it as a phytosanitary pest. Consequently, it is necessary to ship fruit to these markets under cold-disinfestation protocols. This has been possible, as until recently, all of these markets could be considered relatively small niche markets. The South African citrus industry exports approximately 130 million cartons of fruit (15 kg equivalent) annually. During the 2017 season, a total of 48 million cartons were exported to the European Union (EU), which is the equivalent of 41% of South Africa’s total export volume, thus making the EU South Africa’s most important export market. In 2013 the European and Mediterranean Plant Protection Organisation (EPPO) conducted a pest risk analysis (PRA) on FCM, leading to the EU declaring it an officially regulated pest for this region, effective of 1 January 2018. Citrus is regarded as a preferred non-native host of FCM and South African citrus was identified as a primary focus due to large volumes being exported to Europe. Shipping under cold disinfestation is not possible with such large volumes of fruit. Additionally, several cultivars would suffer high levels of chilling injury under such conditions. In this study, an Integrated Management System was tested with pre- and postharvest controls to test the hypothesis that pre-harvest interventions resulted in lower post-harvest infection. Thirty orchards ranging from soft citrus cultivars such as Nule and Nova Mandarins, to Navel orange cultivars such as Newhall, Palmer and Late Navel and ending with Valencia cultivars such as Midknight and Delta, were identified for this study. This system relies on pre-harvest inspections such as FCM trap counts and fruit infestation on data trees in every orchard, with associated thresholds for action or continued compliance. Inspections were conducted on a weekly basis. There was a significant relationship between the moth catches and FCM infestation for the full monitoring period, using a two-week lag period for infestation. Inspections of harvested fruit were conducted at the packhouse to determine FCM infestation. This included inspection of the fruit on delivery to the packhouse, on the packing line, and a final fruit sample taken from the packed product and inspected for FCM. The highest levels of infestation were recorded on the Navel cultivars, thus confirming that Navels cultivars are a preferred host for FCM. Significant positive relationships were recorded between FCM infestation during the last 4 weeks before harvest and the level of infestation in the fruit delivered to the packhouse and between the fruit delivered to the packhouse and in the fruit packed in a carton for export. There was a substantial reduction in infestation between the fruit delivered to the packhouse and the fruit packed in a carton for export, with certain orchards recording as much as a 93% reduction in the fruit packed in a carton, which indicated that the packhouse could effectively identify and remove FCM infested fruit. The outcome of the study is that a holistic management approach minimizes the risk of FCM in citrus fruit destined for export and therefore mitigate the risk associated with FCM.
- Full Text:
- Date Issued: 2019
Bioavailability of nutrients in a diet enriched with moringa oleifera lam. Leaves using wistar rats
- Authors: Mhlomi, Yanga Nonelela
- Date: 2019
- Subjects: Moringa Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14594 , vital:40018
- Description: This study investigated the nutritional composition and bioavailability of nutrients in Moringa oleifera leaf meal from South African ecotype. Nutritional evaluation (proximate, mineral, vitamins and antinutrients, amino acids and fatty acids analyses) was performed using AOAC, ICP-OES and GC+MS techniques respectively. Bioavailability of nutrients involved formulation of diets deficient in minerals and vitamins; and proteins supplemented with Moringa oleifera leaf meal (MOLM) at 0, 3, 5 and 10% respectively. Growth performance, hematological, biochemical and histopathological evaluations were used to assess the effect of MOLM supplementation. Proximate and mineral evaluation revealed that the leaves were rich in protein (28.72%) and carbohydrate (28.84%), calcium content was (1603.33 mg/100g), potassium (1690 mg/100g), zinc (13.03 mg/100g) and iron (21.13 mg/100g). Vitamin E content was the highest (89.43 mg/100g) followed by vitamic C (24.9 mg/100g) and vitamin A (12.98 mg/100g). Fatty acids analysis detected were fifteen of which polyunsaturated fatty acid linoleic acid (56.36) and alpha-linolenic acid (687.58) were highest and behenic acid (22:0) characteristics of Moringa (4.11%) were detected. Seven of the detected fatty acids were saturated fatty acids, though relatively low, with stearic acid having the highest value. On the other hand fifteen of the amino acids, 7 were essential (valine, leucine, isoleucine, methionine, threonine and phenylalanine) were detected; while alanine, proline, serine, aspartic acid, cysteine, glutamic acid, asparagine and tyrosine were non- essential amino acid. Moringa oleifera had low quantities of antinutrients in relation to minerals, thus nutrients will easily ne available. Amino and fatty acids profile of nutrient deficient diets supplemented with MOLM revealed that six essential amino acids were detected in the diets. However, the essential amino acid (EAA) in MOLM with the highest value was threonine (500.47±23.03mg/L), while the lowest was methionine (75.65±5.31mg/L). Leucine was highest in PD10 (234.32±27.98 mg/l) 15 and lowest in PD3. Predominant amino acid in VMD diet was glutamic acid (966.76±208.92 mg/l), while methionine was lowest (197.14±35.90). Caproic acid was the most prominent unsaturated fatty acid in the diets and was highest in the PD diet. Palmitoleic acid was highest in the control diet (8.19±0.56 mg/L) and lowest in PD3 but an increase was observed as the levels of MOLM increased in the diets. Linoleic acid values obtained were significantly higher in PD diet, lower in control diet, compared to other diets. Linolenic acid (C18-3n6) was higher in PD10 (63.48±3.84 mg/L) compared to the control diet (6.05±0.14 mg/L). The highest unsaturated fatty acid in all the feed samples was linoleic acids ranging from 54.48±5.61 to 296.26±7.20 mg/L. the highest omega-3 (n-3) fatty acid content (63.48±3.38 mg/L) was in PD10 and was almost 10 times higher than the value recorded for control. Rats treated on vitamin mineral deficient (VMD) diet showed no significant changes in growth performances and blood parameters except in certain indices. Rats on VMD diet had lowest haemoglobin levels, whereas haemoglobin increased with MOLM levels. No significant differences in haematocrit, MCH, MCHC, platelets, RDW and MPV were observed in all treatments and control. However, VMD rats showed decrease in haemoglobin, increase in WBC and platelets. Electrolytes and glucose for all treatments and control were not significantly different, but, control and VMD10 diets rats showed significantly higher values for creatinine compared to MOLM diets; total protein and albumin increased with MOLM and were higher than in VMD and control rats. Serum activities of liver, cardiac, adrenal marker enzymes were significantly lower in MOLM rats compared to VMD and control. Mild congestion in VMD and VMD3 rat’s liver and diffused congestion in the kidney of VMD diet fed rats was observed. Protein deficient diets supplemented with MOLM had a negative impact on feed intake and growth parameters. Rats fed PD and PD5 consumed significantly less diet than those fed PD10, PD3 diets respectively. White blood cells decreased with increasing levels of MOLM 16 supplementation. Differential white cell count (Neutrophils, lymphocytes, monocytes, eosinophils and basophils) followed the same trend though not statistically significant (P>0.05). Furthermore, histopathological evaluation of organs revealed that no abnormalities were in heart and liver and kidney of rats fed on the control diet, while mild congestion in the liver and myocardium (heart) were observed in rats fed with protein deficient diet. No visible abnormalities were observed in the heart, kidney and liver of animals on the PD 10 diet, but myocardial fibres showing intense eosinophilia was detected in heart muscles of rats fed PD and PD3 diets. In this study, MOLM had a negative impact on feed intake and growth performance of animals and haematology. Blood biochemistry and histology suggest that MOLM has the potential of defending the body against infection with hematinic and blood enhancing qualities. Protein deficiency led to a significant elevation in the serum lipid profile of rats especially cholesterol even with increase in MOLM. PD10 had the highest triglycerides content when compared to the control but was lower (p>0.05) to that of PD. There was an increase in crude fat, ADF, NDF and protein in faecal samples of rats supplemented with MOLM diets while a decrease in moisture and ash was observed compared to the control.Vitamin and mineral deficiency resulted in significant decrease in serum cholesterol, triglycerides and HDL-C when compared to the control. There was a slight increase in excretion for all elements with increasing MOLM. Total removal of minerals and vitamins from the VMD experimental diets seemed not to have any visible negative impact on performance of the rats probably because of residual micronutrients present in other ingredients used in the feed formulation. MOLM could not replace protein in protein deficient diets.
- Full Text:
- Date Issued: 2019
- Authors: Mhlomi, Yanga Nonelela
- Date: 2019
- Subjects: Moringa Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14594 , vital:40018
- Description: This study investigated the nutritional composition and bioavailability of nutrients in Moringa oleifera leaf meal from South African ecotype. Nutritional evaluation (proximate, mineral, vitamins and antinutrients, amino acids and fatty acids analyses) was performed using AOAC, ICP-OES and GC+MS techniques respectively. Bioavailability of nutrients involved formulation of diets deficient in minerals and vitamins; and proteins supplemented with Moringa oleifera leaf meal (MOLM) at 0, 3, 5 and 10% respectively. Growth performance, hematological, biochemical and histopathological evaluations were used to assess the effect of MOLM supplementation. Proximate and mineral evaluation revealed that the leaves were rich in protein (28.72%) and carbohydrate (28.84%), calcium content was (1603.33 mg/100g), potassium (1690 mg/100g), zinc (13.03 mg/100g) and iron (21.13 mg/100g). Vitamin E content was the highest (89.43 mg/100g) followed by vitamic C (24.9 mg/100g) and vitamin A (12.98 mg/100g). Fatty acids analysis detected were fifteen of which polyunsaturated fatty acid linoleic acid (56.36) and alpha-linolenic acid (687.58) were highest and behenic acid (22:0) characteristics of Moringa (4.11%) were detected. Seven of the detected fatty acids were saturated fatty acids, though relatively low, with stearic acid having the highest value. On the other hand fifteen of the amino acids, 7 were essential (valine, leucine, isoleucine, methionine, threonine and phenylalanine) were detected; while alanine, proline, serine, aspartic acid, cysteine, glutamic acid, asparagine and tyrosine were non- essential amino acid. Moringa oleifera had low quantities of antinutrients in relation to minerals, thus nutrients will easily ne available. Amino and fatty acids profile of nutrient deficient diets supplemented with MOLM revealed that six essential amino acids were detected in the diets. However, the essential amino acid (EAA) in MOLM with the highest value was threonine (500.47±23.03mg/L), while the lowest was methionine (75.65±5.31mg/L). Leucine was highest in PD10 (234.32±27.98 mg/l) 15 and lowest in PD3. Predominant amino acid in VMD diet was glutamic acid (966.76±208.92 mg/l), while methionine was lowest (197.14±35.90). Caproic acid was the most prominent unsaturated fatty acid in the diets and was highest in the PD diet. Palmitoleic acid was highest in the control diet (8.19±0.56 mg/L) and lowest in PD3 but an increase was observed as the levels of MOLM increased in the diets. Linoleic acid values obtained were significantly higher in PD diet, lower in control diet, compared to other diets. Linolenic acid (C18-3n6) was higher in PD10 (63.48±3.84 mg/L) compared to the control diet (6.05±0.14 mg/L). The highest unsaturated fatty acid in all the feed samples was linoleic acids ranging from 54.48±5.61 to 296.26±7.20 mg/L. the highest omega-3 (n-3) fatty acid content (63.48±3.38 mg/L) was in PD10 and was almost 10 times higher than the value recorded for control. Rats treated on vitamin mineral deficient (VMD) diet showed no significant changes in growth performances and blood parameters except in certain indices. Rats on VMD diet had lowest haemoglobin levels, whereas haemoglobin increased with MOLM levels. No significant differences in haematocrit, MCH, MCHC, platelets, RDW and MPV were observed in all treatments and control. However, VMD rats showed decrease in haemoglobin, increase in WBC and platelets. Electrolytes and glucose for all treatments and control were not significantly different, but, control and VMD10 diets rats showed significantly higher values for creatinine compared to MOLM diets; total protein and albumin increased with MOLM and were higher than in VMD and control rats. Serum activities of liver, cardiac, adrenal marker enzymes were significantly lower in MOLM rats compared to VMD and control. Mild congestion in VMD and VMD3 rat’s liver and diffused congestion in the kidney of VMD diet fed rats was observed. Protein deficient diets supplemented with MOLM had a negative impact on feed intake and growth parameters. Rats fed PD and PD5 consumed significantly less diet than those fed PD10, PD3 diets respectively. White blood cells decreased with increasing levels of MOLM 16 supplementation. Differential white cell count (Neutrophils, lymphocytes, monocytes, eosinophils and basophils) followed the same trend though not statistically significant (P>0.05). Furthermore, histopathological evaluation of organs revealed that no abnormalities were in heart and liver and kidney of rats fed on the control diet, while mild congestion in the liver and myocardium (heart) were observed in rats fed with protein deficient diet. No visible abnormalities were observed in the heart, kidney and liver of animals on the PD 10 diet, but myocardial fibres showing intense eosinophilia was detected in heart muscles of rats fed PD and PD3 diets. In this study, MOLM had a negative impact on feed intake and growth performance of animals and haematology. Blood biochemistry and histology suggest that MOLM has the potential of defending the body against infection with hematinic and blood enhancing qualities. Protein deficiency led to a significant elevation in the serum lipid profile of rats especially cholesterol even with increase in MOLM. PD10 had the highest triglycerides content when compared to the control but was lower (p>0.05) to that of PD. There was an increase in crude fat, ADF, NDF and protein in faecal samples of rats supplemented with MOLM diets while a decrease in moisture and ash was observed compared to the control.Vitamin and mineral deficiency resulted in significant decrease in serum cholesterol, triglycerides and HDL-C when compared to the control. There was a slight increase in excretion for all elements with increasing MOLM. Total removal of minerals and vitamins from the VMD experimental diets seemed not to have any visible negative impact on performance of the rats probably because of residual micronutrients present in other ingredients used in the feed formulation. MOLM could not replace protein in protein deficient diets.
- Full Text:
- Date Issued: 2019
How do urban dwellers identify with features within urban green spaces in the Eastern Cape?
- Authors: Manyani, Amanda
- Date: 2019
- Subjects: Land use, Urban -- South Africa , Greenbelts -- South Africa , City planning -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95596 , vital:31174
- Description: Public urban green spaces contain natural and artificial features which play crucial roles in supporting urban social-ecological systems, a fact now recognized globally. The various natural and artificial features contained in public urban green spaces are said to be key contributors to the quality of life and well-being of urban dwellers. Nevertheless, this has been largely ignored in urban design in South Africa, especially in the poorer township and Reconstruction Development Program (RDP) areas. At the individual household and community levels within the poorer communities, the provision of green spaces and trees, as well as recreation facilities, is well below world standards, and much less than what is available in the more affluent areas of South African towns. Additionally, most research on the links between nature and human well-being in urban contexts comes from developed world contexts which adopt a westernized view of the relationship. Yet, in many societies of the Global South, including South Africa, worldviews and experiences of nature in green spaces and use of other recreational features takes on different meanings to those of the Global North. To show these differences, a combination of methods was used in this study, different types of green spaces were assessed and evaluated by structured observations so as to record the features present within the spaces. A survey of 360 households was conducted by targeting green space users and households within 100 metres from a green space. Results indicated that, across all the green space types, formal green spaces had a low cover of shrubs, trees and herbs whilst having high lawn cover. Furthermore, vegetation had poor rating across all the green spaces since the vegetation was either overgrown herbs, dense thickets of shrubs and mostly alien trees that were either diseased or forked. Similar to the disparity in the composition and structure of vegetation within the green spaces, there was a wide variability in the composition of recreational features and amenities across the green spaces. The formal green spaces had the most amenities like play equipment, shelter and seating. Informal green spaces and commonages had little or no recreational features available. The attributes of these spaces therefore influenced the reasons for visiting as more than 90 % of the respondents simply used the spaces for transit. With regards to attitudes and preferences towards particular features, they were emerging sense of strong negative feelings towards natural features. Most respondents emphasized the need for green spaces that are well laid out with maintained lawns, recreational facilities and open vegetation. Thus, the current design and available features within the studied urban green spaces do not meet local needs and aspirations and thus do not contribute to better well-being and quality of life as much as they could. Specifically, the various health benefits linked with being in contact with nature in the public green spaces were not evident in this study. The South African specific context in green space use, perception and people’s preferences is thus crucial for urban planning and sustainability.
- Full Text:
- Date Issued: 2019
- Authors: Manyani, Amanda
- Date: 2019
- Subjects: Land use, Urban -- South Africa , Greenbelts -- South Africa , City planning -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95596 , vital:31174
- Description: Public urban green spaces contain natural and artificial features which play crucial roles in supporting urban social-ecological systems, a fact now recognized globally. The various natural and artificial features contained in public urban green spaces are said to be key contributors to the quality of life and well-being of urban dwellers. Nevertheless, this has been largely ignored in urban design in South Africa, especially in the poorer township and Reconstruction Development Program (RDP) areas. At the individual household and community levels within the poorer communities, the provision of green spaces and trees, as well as recreation facilities, is well below world standards, and much less than what is available in the more affluent areas of South African towns. Additionally, most research on the links between nature and human well-being in urban contexts comes from developed world contexts which adopt a westernized view of the relationship. Yet, in many societies of the Global South, including South Africa, worldviews and experiences of nature in green spaces and use of other recreational features takes on different meanings to those of the Global North. To show these differences, a combination of methods was used in this study, different types of green spaces were assessed and evaluated by structured observations so as to record the features present within the spaces. A survey of 360 households was conducted by targeting green space users and households within 100 metres from a green space. Results indicated that, across all the green space types, formal green spaces had a low cover of shrubs, trees and herbs whilst having high lawn cover. Furthermore, vegetation had poor rating across all the green spaces since the vegetation was either overgrown herbs, dense thickets of shrubs and mostly alien trees that were either diseased or forked. Similar to the disparity in the composition and structure of vegetation within the green spaces, there was a wide variability in the composition of recreational features and amenities across the green spaces. The formal green spaces had the most amenities like play equipment, shelter and seating. Informal green spaces and commonages had little or no recreational features available. The attributes of these spaces therefore influenced the reasons for visiting as more than 90 % of the respondents simply used the spaces for transit. With regards to attitudes and preferences towards particular features, they were emerging sense of strong negative feelings towards natural features. Most respondents emphasized the need for green spaces that are well laid out with maintained lawns, recreational facilities and open vegetation. Thus, the current design and available features within the studied urban green spaces do not meet local needs and aspirations and thus do not contribute to better well-being and quality of life as much as they could. Specifically, the various health benefits linked with being in contact with nature in the public green spaces were not evident in this study. The South African specific context in green space use, perception and people’s preferences is thus crucial for urban planning and sustainability.
- Full Text:
- Date Issued: 2019
The use of insecticides and cultural control for the management of soil-borne pests during plantation establishment
- Authors: Siwela, Evidence Miyelani
- Date: 2019
- Subjects: Insecticides , Plant diseases Pests -- Control Pesticides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43446 , vital:36882
- Description: Over the past decades, the productivity of South African forestry plantations has been negatively impacted by abiotic (fire, hail, wind, frost, drought etc.) and biotic factors (pests and diseases). The biotic component of insect pests and pathogens cause significant loss to the forestry industry and this affects the productivity, financial viability and long-term sustainability of plantations. Common establishment insect pests and diseases in South Africa include the pine bark beetle (Hylastes angustatus), cutworms (Agrotis spp), white grubs (Scarabaeidae larvae), rhizina root rot (Rhizina undulata), fusarium pitch canker (Fusarium circinatum), and pine dieback (Diplodia pinea). Soil-borne pests, mainly white grubs and cutworms can contribute to high seedling mortality following the re-establishment of eucalypts and wattle. Synthetic insecticides used for their control include alpha-cypermethrin, deltamethrin, and imidacloprid. However, all these insecticides are considered highly hazardous to the environment and/or human health and can no longer be considered for use in South African plantations. A need has therefore arisen to find and screen alternative products (synthetic and/or natural), that are not only environmentally safe for use, but also effective for the control of soil-borne pests during plantation establishment. In addition, these products can then be combined with other control mechanisms (such as cultural and biological control) to form an integrated pest management strategy. To address the above, a series of research trials were implemented with the outcomes discussed below. Two trials were implemented in KwaZulu-Natal (Demagtenberg) and Mpumalanga (Klipkraal) to determine if seedling size in combination with, or without an insecticide would result in improved survival of Pinus Patula. The main factors tested were Root Plug Volume (36 cm3 versus 103 cm3), Seedling Age (Standard [smaller] versus Older [larger]), and Pesticide application (untreated versus treated). Seedling quality was assessed in terms of Shoot:Root ratio, optimum Height (Ht in cm), and root collar diameter (Rcd in mm) before planting, with tree growth variates measured at planting, and then at regular intervals. The final measurements were taken at 7 years and 2 months for Demagtenberg and 5 years and 1 month for Klipkraal. For both trials, the Root Growth Potential (RGP) and total Plant Quality Index (PQI) indicated that Root Plug Volume 36 cm3 and Seedling Age (SA)_Standard (smaller) had a better Sturdiness ratio and Shoot:Root ratio compared to that of Root Plug Volume 103 cm3 and Seedling Age (SA)_Older (larger), with these benefits translated into improved field performance. The diameter at breast height (Dbh), Basal area (BA), Stocking and Volume indicated that SA_Standard and Root Plug Volume 36 cm3 resulted in better survival and growth than that of SA_Older (larger) seedlings and Root Plug Volume 103 cm3. The application of a Pesticide resulted in improved survival and growth at Klipkraal, but not at Demagtenberg. This indicated the presence of soil-borne pests at this site. In addition, the interaction between Pesticide application and SA_Standard resulted in a significantly larger BA than all other treatments only at Klipkraal, which indicates that both improved seedling quality and pesticides contributed to improved performance. One trial was established to Eucalyptus dunnii William Dunn at Umvoti North to investigate the effectiveness of the synthetic insecticides (deltamethrin, clothianidin, imidacloprid, imidacloprid + fertilizer, imidacloprid + clothianidin + fertilizer) and two natural products (azadirachtin and potassium silicate) for the control of soil-borne pests following planting. Groundline diameter (Gld), Height (Ht) and survival were assessed over a six-month period. Despite the selection of a site known to have a high incidence of soil-borne pests, few soil-borne pest were detected on the site for the trial duration, with no treatment differences observed for any of the tree growth variates. Significant differences were observed for foliar discolouration (possible phytotoxicity), however, these results were inconclusive as majority of the affected treatments (those that survived) showed full recovery. Three-month results from 12 eucalypt trials in KwaZulu-Natal, South Africa were compared to determine the benefits (including costs) of insecticides for the control of soil-borne pests. The 12 trials were selected to represent different physiographic regions, mainly within the warm temperate regions where white grubs and cutworms are likely to occur. Data for the trials were obtained from previous management research (published documents) and included six where mortality was the only variate assessed, with the Ht and Gld also assessed in the remaining six trials. There was a ≥ 2.5% increase in survival in seven of the 12 trials through the use of insecticides relative to the control, although only four of these seven were statistically significant. Of the 12 trials, the use of insecticides resulted in > 90% survival compared to the control at Mistley (93 versus 83%), Bloemendal (96 versus 62%) and Enon (burn) (96 versus 89%). At Garfield, Vulindlela, and Baynesfield, survival in both the treated and untreated treatments was below 90%, whereas both the treated and untreated treatments were above 90% at Rustig, Greenhill, Enon (slash), Umvoti, Dargle and Umvoti North. This data indicates that where soil-borne pests are present, the application of an insecticide is beneficial. Due to the costs associated with insecticide application, the challenge will be to determine which are high-risk sites that require treatment with an insecticide. Results from these trials indicate that on sites where soil-borne pests are present (and active), the application of insecticides is beneficial. However, even if present, the level of impact is less obvious, and possibly influenced by life cycle stage, site management and climate. The testing of alternative and less highly hazardous insecticides indicated the potential future use of insecticides in terms of limited seedling phytotoxicity (some of the products tested). To understand more fully the extent of their efficacy, these products would need to be re-tested again on sites where soil-borne pests are active. Optimum establishment practices, together with the planting of quality seedlings and application of an approved insecticide, will all contribute to improved survival and growth. Perhaps the biggest challenge will be the determination of soil pest activity, such that the application of pesticides can be limited to those sites where control is necessary..
- Full Text:
- Date Issued: 2019
- Authors: Siwela, Evidence Miyelani
- Date: 2019
- Subjects: Insecticides , Plant diseases Pests -- Control Pesticides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43446 , vital:36882
- Description: Over the past decades, the productivity of South African forestry plantations has been negatively impacted by abiotic (fire, hail, wind, frost, drought etc.) and biotic factors (pests and diseases). The biotic component of insect pests and pathogens cause significant loss to the forestry industry and this affects the productivity, financial viability and long-term sustainability of plantations. Common establishment insect pests and diseases in South Africa include the pine bark beetle (Hylastes angustatus), cutworms (Agrotis spp), white grubs (Scarabaeidae larvae), rhizina root rot (Rhizina undulata), fusarium pitch canker (Fusarium circinatum), and pine dieback (Diplodia pinea). Soil-borne pests, mainly white grubs and cutworms can contribute to high seedling mortality following the re-establishment of eucalypts and wattle. Synthetic insecticides used for their control include alpha-cypermethrin, deltamethrin, and imidacloprid. However, all these insecticides are considered highly hazardous to the environment and/or human health and can no longer be considered for use in South African plantations. A need has therefore arisen to find and screen alternative products (synthetic and/or natural), that are not only environmentally safe for use, but also effective for the control of soil-borne pests during plantation establishment. In addition, these products can then be combined with other control mechanisms (such as cultural and biological control) to form an integrated pest management strategy. To address the above, a series of research trials were implemented with the outcomes discussed below. Two trials were implemented in KwaZulu-Natal (Demagtenberg) and Mpumalanga (Klipkraal) to determine if seedling size in combination with, or without an insecticide would result in improved survival of Pinus Patula. The main factors tested were Root Plug Volume (36 cm3 versus 103 cm3), Seedling Age (Standard [smaller] versus Older [larger]), and Pesticide application (untreated versus treated). Seedling quality was assessed in terms of Shoot:Root ratio, optimum Height (Ht in cm), and root collar diameter (Rcd in mm) before planting, with tree growth variates measured at planting, and then at regular intervals. The final measurements were taken at 7 years and 2 months for Demagtenberg and 5 years and 1 month for Klipkraal. For both trials, the Root Growth Potential (RGP) and total Plant Quality Index (PQI) indicated that Root Plug Volume 36 cm3 and Seedling Age (SA)_Standard (smaller) had a better Sturdiness ratio and Shoot:Root ratio compared to that of Root Plug Volume 103 cm3 and Seedling Age (SA)_Older (larger), with these benefits translated into improved field performance. The diameter at breast height (Dbh), Basal area (BA), Stocking and Volume indicated that SA_Standard and Root Plug Volume 36 cm3 resulted in better survival and growth than that of SA_Older (larger) seedlings and Root Plug Volume 103 cm3. The application of a Pesticide resulted in improved survival and growth at Klipkraal, but not at Demagtenberg. This indicated the presence of soil-borne pests at this site. In addition, the interaction between Pesticide application and SA_Standard resulted in a significantly larger BA than all other treatments only at Klipkraal, which indicates that both improved seedling quality and pesticides contributed to improved performance. One trial was established to Eucalyptus dunnii William Dunn at Umvoti North to investigate the effectiveness of the synthetic insecticides (deltamethrin, clothianidin, imidacloprid, imidacloprid + fertilizer, imidacloprid + clothianidin + fertilizer) and two natural products (azadirachtin and potassium silicate) for the control of soil-borne pests following planting. Groundline diameter (Gld), Height (Ht) and survival were assessed over a six-month period. Despite the selection of a site known to have a high incidence of soil-borne pests, few soil-borne pest were detected on the site for the trial duration, with no treatment differences observed for any of the tree growth variates. Significant differences were observed for foliar discolouration (possible phytotoxicity), however, these results were inconclusive as majority of the affected treatments (those that survived) showed full recovery. Three-month results from 12 eucalypt trials in KwaZulu-Natal, South Africa were compared to determine the benefits (including costs) of insecticides for the control of soil-borne pests. The 12 trials were selected to represent different physiographic regions, mainly within the warm temperate regions where white grubs and cutworms are likely to occur. Data for the trials were obtained from previous management research (published documents) and included six where mortality was the only variate assessed, with the Ht and Gld also assessed in the remaining six trials. There was a ≥ 2.5% increase in survival in seven of the 12 trials through the use of insecticides relative to the control, although only four of these seven were statistically significant. Of the 12 trials, the use of insecticides resulted in > 90% survival compared to the control at Mistley (93 versus 83%), Bloemendal (96 versus 62%) and Enon (burn) (96 versus 89%). At Garfield, Vulindlela, and Baynesfield, survival in both the treated and untreated treatments was below 90%, whereas both the treated and untreated treatments were above 90% at Rustig, Greenhill, Enon (slash), Umvoti, Dargle and Umvoti North. This data indicates that where soil-borne pests are present, the application of an insecticide is beneficial. Due to the costs associated with insecticide application, the challenge will be to determine which are high-risk sites that require treatment with an insecticide. Results from these trials indicate that on sites where soil-borne pests are present (and active), the application of insecticides is beneficial. However, even if present, the level of impact is less obvious, and possibly influenced by life cycle stage, site management and climate. The testing of alternative and less highly hazardous insecticides indicated the potential future use of insecticides in terms of limited seedling phytotoxicity (some of the products tested). To understand more fully the extent of their efficacy, these products would need to be re-tested again on sites where soil-borne pests are active. Optimum establishment practices, together with the planting of quality seedlings and application of an approved insecticide, will all contribute to improved survival and growth. Perhaps the biggest challenge will be the determination of soil pest activity, such that the application of pesticides can be limited to those sites where control is necessary..
- Full Text:
- Date Issued: 2019
Development of silver-based polyaniline nanocomposite for electrochemical oxidation and detection of organosulfur compounds
- Authors: Shoba, Siyabonga
- Date: 2019
- Subjects: Polyethylene -- Analysis , Composite materials Nanocomposites (Materials)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43600 , vital:36928
- Description: Human activities such as combustion of fossil fuels through automobiles, factories and electricity generation using coal results in major productions of sulfur dioxide to the atmosphere. The sulfur dioxide gas chemically reacts with other substances (i.e. water and oxygen) in the atmosphere and produces acidic pollutants. These acidic pollutants exist in both wet and dry form and before they are deposited on the earth’s surface, they can travel long distances carried by the wind. They are deposited in a wet form as rain, snow, fog and sleet and in a dry form as gases or particles. This has led to the mandated 10 ppm S in fuel by the environmental protection agency (EPA). Electrochemical desulfurization (ECDS) has been reported as an innovative technique for removing sulfur via redox processes. ECDS technique is a low costs process as no catalysts and oxidant are involved and it is a green technology (environmental benignity), thus making the process more economical than conventional hydrodesulfurization (HDS) technologies. Modification of electrodes for electrochemistry as well as electrodeposition of metal nanoparticles offers interesting electrochemical activities due to their reduced size and high surface area to volume ratio. Electrochemical oxidation of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was analysed in acetonitrile using carbon electrodes modified with silver (Ag)-polyaniline (PAni) based nanocomposites (GCE/PAni/Ag and GCE/Ag). The PAni, PAni/Ag composites were characterized using spectroscopic (FT-IR, XRD, XPS) and microscopic (SEM and TEM) techniques. SEM confirmed that the synthesized PAni and PAni/Ag presented an amorphous granular morphology with the aggregation of small irregular particle sizes. Cyclic voltammetry of BT, DBT and 4,6-DMDBT on the modified glassy carbon (GCE) electrode show chemically irreversible anodic peaks which corresponds to electron transfer of sulfur to form sulfoxide and lastly sulfone containing compounds. The overall conversion yield of DBT and 4,6-DMDBT to respective sulfones increased as water content increases. Products were characterized by means of gas chromatograph coupled to mass spectrometer (GC-MS), 1H and 13C NMR. Similarly, silver-modified Glassy Carbon (GCE) electrode was used for the electrochemical detection of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in the presence of naphthalene (NP) and carbazole (CR). The electrochemical response of BT, DBT and 4,6-DMDBT on the modified electrode was determined using Differential Pulse Voltammetry (DPV) in acetonitrile. The electrochemical behaviour of BT, DBT and 4,6-DMDBT showed that the modified electrode exhibited excellent oxidation electro-catalytic activity. The dynamic range for the organosulfur compounds determination was from 1 to 11 ppm with detection limits (LOD) of 0.60 ppmS, 0.41 ppmS and 0.21 ppmS for BT, DBT and 4,6-DMDBT, respectively. Electrochemical sensor showed excellent selectivity of the compounds in the presence of interfering compounds such as naphthalene, carbazole and thiourea over the studied range of concentrations. The prepared electrode exhibited satisfactory reusability and stability after four successive measurement. It has been demonstrated in this study that modified glassy carbon (GCE) electrode (GCE/PAni/Ag) can be successfully used for the assay of sulfur containing compounds such as BT, DBT and 4, 6-DMDBT in petroleum samples.
- Full Text:
- Date Issued: 2019
- Authors: Shoba, Siyabonga
- Date: 2019
- Subjects: Polyethylene -- Analysis , Composite materials Nanocomposites (Materials)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43600 , vital:36928
- Description: Human activities such as combustion of fossil fuels through automobiles, factories and electricity generation using coal results in major productions of sulfur dioxide to the atmosphere. The sulfur dioxide gas chemically reacts with other substances (i.e. water and oxygen) in the atmosphere and produces acidic pollutants. These acidic pollutants exist in both wet and dry form and before they are deposited on the earth’s surface, they can travel long distances carried by the wind. They are deposited in a wet form as rain, snow, fog and sleet and in a dry form as gases or particles. This has led to the mandated 10 ppm S in fuel by the environmental protection agency (EPA). Electrochemical desulfurization (ECDS) has been reported as an innovative technique for removing sulfur via redox processes. ECDS technique is a low costs process as no catalysts and oxidant are involved and it is a green technology (environmental benignity), thus making the process more economical than conventional hydrodesulfurization (HDS) technologies. Modification of electrodes for electrochemistry as well as electrodeposition of metal nanoparticles offers interesting electrochemical activities due to their reduced size and high surface area to volume ratio. Electrochemical oxidation of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was analysed in acetonitrile using carbon electrodes modified with silver (Ag)-polyaniline (PAni) based nanocomposites (GCE/PAni/Ag and GCE/Ag). The PAni, PAni/Ag composites were characterized using spectroscopic (FT-IR, XRD, XPS) and microscopic (SEM and TEM) techniques. SEM confirmed that the synthesized PAni and PAni/Ag presented an amorphous granular morphology with the aggregation of small irregular particle sizes. Cyclic voltammetry of BT, DBT and 4,6-DMDBT on the modified glassy carbon (GCE) electrode show chemically irreversible anodic peaks which corresponds to electron transfer of sulfur to form sulfoxide and lastly sulfone containing compounds. The overall conversion yield of DBT and 4,6-DMDBT to respective sulfones increased as water content increases. Products were characterized by means of gas chromatograph coupled to mass spectrometer (GC-MS), 1H and 13C NMR. Similarly, silver-modified Glassy Carbon (GCE) electrode was used for the electrochemical detection of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in the presence of naphthalene (NP) and carbazole (CR). The electrochemical response of BT, DBT and 4,6-DMDBT on the modified electrode was determined using Differential Pulse Voltammetry (DPV) in acetonitrile. The electrochemical behaviour of BT, DBT and 4,6-DMDBT showed that the modified electrode exhibited excellent oxidation electro-catalytic activity. The dynamic range for the organosulfur compounds determination was from 1 to 11 ppm with detection limits (LOD) of 0.60 ppmS, 0.41 ppmS and 0.21 ppmS for BT, DBT and 4,6-DMDBT, respectively. Electrochemical sensor showed excellent selectivity of the compounds in the presence of interfering compounds such as naphthalene, carbazole and thiourea over the studied range of concentrations. The prepared electrode exhibited satisfactory reusability and stability after four successive measurement. It has been demonstrated in this study that modified glassy carbon (GCE) electrode (GCE/PAni/Ag) can be successfully used for the assay of sulfur containing compounds such as BT, DBT and 4, 6-DMDBT in petroleum samples.
- Full Text:
- Date Issued: 2019
Amaranth (Amaranthus cruentus) growth and nutritional contents as affected by nitrogen and potassium fertiliser and plant density
- Authors: Mamvura, Luckmore
- Date: 2019
- Subjects: Weeds -- Control -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17249 , vital:40869
- Description: The research was conducted to determine the response of amaranth growth and development to different rates of nitrogen and potassium fertilizer, the effect of plant density on herbage yield and weed management, effect of leaf age and stems on nutritional value of amaranths. The research was conducted at the University of Fort Hare Research Farm and University of Fort Hare glasshouse. For the fertilizer trial, a 4 x 3 factorial experiment: nitrogen at four levels (50kg/ha; 100kg/ha; 150kg/ha; 200kg/ha) and potassium at three levels (50kg/ha; 75kg/ha; 100kg/ha) was applied. Phosphorus was applied at 50kg/ha. The experiment was laid as randomised complete block design (RCBD) with 4 blocks (replication). The results showed that application of nitrogen and potassium treatments significantly (P < 0.05) increased plant height, stem girth and number of leaves per plant which in turn increased the crop economic leaf vegetative yield. The results also showed that at high rates of nitrogen and potassium, high vegetative yields were achieved in most cases. There was no interaction (P < 0.05) between nitrogen and potassium. Second experiment, the twelve treatments used in fertilizer trial were imposed under four different amaranth plant densities (1 200 000, 1400 000, 1600 000 and 1800 000 pph) at field level to find out growth and development performance of amaranth. In addition, at the same time investigating the effectiveness of plant density on weeds management using split plot design. The different planting densities were allocated to the main plots laid-out in RCBD. The results showed that there was no significant difference (P < 0.05) on the number of weeds under four plant densities. The results showed that different plant densities did not prevent weeds germination but the amaranths tolerate the negative effects of weeds. The nutritional analysis results showed that amaranth synthesised close to above recommended nutritional level despite different treatments applied. The third experiment: stems, lower and upper leaves were harvested separately and their nutritional composition was analysed. The results showed that the nutritional composition of stems, lower leaves and upper leaves were significantly different (P < 0.05) in most cases. Lower leaves dominated nutritional content for: crude protein crude fibre, carbohydrates, and calcium. The stems recorded least nutritional content on crude protein, crude fat, carbohydrates, calcium, potassium and sodium
- Full Text:
- Date Issued: 2019
- Authors: Mamvura, Luckmore
- Date: 2019
- Subjects: Weeds -- Control -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17249 , vital:40869
- Description: The research was conducted to determine the response of amaranth growth and development to different rates of nitrogen and potassium fertilizer, the effect of plant density on herbage yield and weed management, effect of leaf age and stems on nutritional value of amaranths. The research was conducted at the University of Fort Hare Research Farm and University of Fort Hare glasshouse. For the fertilizer trial, a 4 x 3 factorial experiment: nitrogen at four levels (50kg/ha; 100kg/ha; 150kg/ha; 200kg/ha) and potassium at three levels (50kg/ha; 75kg/ha; 100kg/ha) was applied. Phosphorus was applied at 50kg/ha. The experiment was laid as randomised complete block design (RCBD) with 4 blocks (replication). The results showed that application of nitrogen and potassium treatments significantly (P < 0.05) increased plant height, stem girth and number of leaves per plant which in turn increased the crop economic leaf vegetative yield. The results also showed that at high rates of nitrogen and potassium, high vegetative yields were achieved in most cases. There was no interaction (P < 0.05) between nitrogen and potassium. Second experiment, the twelve treatments used in fertilizer trial were imposed under four different amaranth plant densities (1 200 000, 1400 000, 1600 000 and 1800 000 pph) at field level to find out growth and development performance of amaranth. In addition, at the same time investigating the effectiveness of plant density on weeds management using split plot design. The different planting densities were allocated to the main plots laid-out in RCBD. The results showed that there was no significant difference (P < 0.05) on the number of weeds under four plant densities. The results showed that different plant densities did not prevent weeds germination but the amaranths tolerate the negative effects of weeds. The nutritional analysis results showed that amaranth synthesised close to above recommended nutritional level despite different treatments applied. The third experiment: stems, lower and upper leaves were harvested separately and their nutritional composition was analysed. The results showed that the nutritional composition of stems, lower leaves and upper leaves were significantly different (P < 0.05) in most cases. Lower leaves dominated nutritional content for: crude protein crude fibre, carbohydrates, and calcium. The stems recorded least nutritional content on crude protein, crude fat, carbohydrates, calcium, potassium and sodium
- Full Text:
- Date Issued: 2019
The extraction of bioactive compounds from spent coffee grounds and their application in a cosmetic formulation
- Authors: Mdubeki, Ntokozo
- Date: 2019
- Subjects: Bioactive compounds , Plants -- bioactive compounds Plant biotechnology Coffee -- Processing Chemistry, Technical Cosmetics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41460 , vital:36485
- Description: Residues obtained during coffee processing, known as spent coffee grounds, are an abundant, low-cost and versatile feedstock for a wide range of high-value biological compounds exhibiting a number of properties which include anti-cellulite and antioxidant properties for skin-care applications. The objective of the present work was to obtain a concentrated extract containing high-value biological methylxanthines and polyphenolic compounds with antioxidant activity from the spent coffee grounds. An investigation of the effect of extraction conditions on the concentration of the bioactive compounds in the extract was done. The recovery of both methylxanthines and the polyphenolic compounds with antioxidant activity was achieved through a one-step extraction method under reduced pressure using a non-toxic solvent blend. Various experimental designs were implemented with the aim of optimising the recovery of the selected bioactive compounds, namely, caffeine, theophylline and theobromine from spent coffee grounds by using solvent blends of water and ethanol. A number of factors considered were: (i) repeatability, (ii) extraction time, (iii) composition of solvent blends, (iv) extraction vacuum (pressure)/temperature settings and (v) operating variables. The results suggested that an optimal recovery of the bioactive compounds will be obtained at a two-hour extraction time with a solvent blend of 100% water to maximise caffeine, theophylline, total phenolic content and percentage antioxidant activity, while extraction of theobromine is optimal using aqueous ethanolic solvent mixtures. The optimal vacuum (pressure) setting was found to be 250 mbar to maximise percentage antioxidant activity. The methylxanthines and total phenolic content were not affected by the vacuum (pressure) and temperature settings. Freezedrying the spent coffee grounds before extraction ensured long-term stability of a reproducible sample and achieved better recovery of the important bioactive compounds. Extraction was performed under reduced pressure in order to reduce solvent reflux temperature and to improve extraction efficiency. The quantitative and qualitative determinations of the above-mentioned high-value compounds were performed by high-performance liquid chromatography (HPLC), which confirmed the presence of the methylxanthines in the extracts. In the extraction of methylxanthines, it was found that caffeine was more abundant in the extract as compared to theophylline and theobromine. The extracts were incorporated into three cosmetic gel formulations. Release studies of caffeine, theobromine and theophylline were performed using the three formulated cosmetic gels with the use of a Franz diffusion cell. It was found that theobromine and theophylline were not detected from the gel samples as they were present in too small amounts in the original extracts and there was no significant difference in the release rates of caffeine when comparing the three different gels. Caffeine was released within 15 minutes. All three gels displayed a pseudoplastic viscosity profile and the different viscosity values of the three gels did not influence the release of caffeine significantly.
- Full Text:
- Date Issued: 2019
- Authors: Mdubeki, Ntokozo
- Date: 2019
- Subjects: Bioactive compounds , Plants -- bioactive compounds Plant biotechnology Coffee -- Processing Chemistry, Technical Cosmetics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41460 , vital:36485
- Description: Residues obtained during coffee processing, known as spent coffee grounds, are an abundant, low-cost and versatile feedstock for a wide range of high-value biological compounds exhibiting a number of properties which include anti-cellulite and antioxidant properties for skin-care applications. The objective of the present work was to obtain a concentrated extract containing high-value biological methylxanthines and polyphenolic compounds with antioxidant activity from the spent coffee grounds. An investigation of the effect of extraction conditions on the concentration of the bioactive compounds in the extract was done. The recovery of both methylxanthines and the polyphenolic compounds with antioxidant activity was achieved through a one-step extraction method under reduced pressure using a non-toxic solvent blend. Various experimental designs were implemented with the aim of optimising the recovery of the selected bioactive compounds, namely, caffeine, theophylline and theobromine from spent coffee grounds by using solvent blends of water and ethanol. A number of factors considered were: (i) repeatability, (ii) extraction time, (iii) composition of solvent blends, (iv) extraction vacuum (pressure)/temperature settings and (v) operating variables. The results suggested that an optimal recovery of the bioactive compounds will be obtained at a two-hour extraction time with a solvent blend of 100% water to maximise caffeine, theophylline, total phenolic content and percentage antioxidant activity, while extraction of theobromine is optimal using aqueous ethanolic solvent mixtures. The optimal vacuum (pressure) setting was found to be 250 mbar to maximise percentage antioxidant activity. The methylxanthines and total phenolic content were not affected by the vacuum (pressure) and temperature settings. Freezedrying the spent coffee grounds before extraction ensured long-term stability of a reproducible sample and achieved better recovery of the important bioactive compounds. Extraction was performed under reduced pressure in order to reduce solvent reflux temperature and to improve extraction efficiency. The quantitative and qualitative determinations of the above-mentioned high-value compounds were performed by high-performance liquid chromatography (HPLC), which confirmed the presence of the methylxanthines in the extracts. In the extraction of methylxanthines, it was found that caffeine was more abundant in the extract as compared to theophylline and theobromine. The extracts were incorporated into three cosmetic gel formulations. Release studies of caffeine, theobromine and theophylline were performed using the three formulated cosmetic gels with the use of a Franz diffusion cell. It was found that theobromine and theophylline were not detected from the gel samples as they were present in too small amounts in the original extracts and there was no significant difference in the release rates of caffeine when comparing the three different gels. Caffeine was released within 15 minutes. All three gels displayed a pseudoplastic viscosity profile and the different viscosity values of the three gels did not influence the release of caffeine significantly.
- Full Text:
- Date Issued: 2019
Ground thermal regimes in Western Dronning Maud Land, Antarctica in 2016
- Authors: Masebe, Consliah Tebogo
- Date: 2019
- Subjects: Climatic changes -- Antarctica , Frozen ground -- Research -- Antarctica , Frozen ground -- Thermal properties -- Antarctica , Queen Maud Land , Earth temperature -- Antarctica , Soil temperature -- Antarctica -- Measurement
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95581 , vital:31173
- Description: Research shows that the climate of Antarctica is changing and, it is vital that the change is monitored to understand how it will affect global ecosystems. Since the International Polar Year (IPY) 2007-2008, research in permafrost studies has grown. However, there are still existing gaps that impede complete understanding of Antarctic cold environments and landscape processes. Permafrost has been noted as one of the major controlling factors of the terrestrial ecosystem dynamics in Antarctica. However, the understanding of Antarctic permafrost, when compared to other cryospheric components, is limited, especially its thermal and physical properties, evolution, as well as links to pedogenesis, hydrology, geomorphic dynamics, and responses to global change. This project provided an understanding and insight to over-arching research that evaluates the state and status of permafrost and the active layer in Dronning Maud Land (DML) through examining short-term variations on ground thermal regimes. The main focus is on understanding the influence of synoptic, diurnal and seasonal events on the active layer in 2016. Analysis of available data shows that ground thermal regimes are influenced by variations in air temperature, pressure, wind speed and to some extent, relative humidity. Subsequently, ground thermal regimes also depend on soil physical characteristics including sediment particle size and bulk density. Furthermore, sediment particle size and bulk density have been found to have a great influence on thermal propagation rates as well as active layer depth; the higher the bulk density, the higher the thermal propagation rate and the lower the bulk density, the lower the thermal propagation rate. Conversely, a large proportion of bigger sediment particle size in soil corresponds with a higher thermal propagation rate and a large proportion of smaller sediment particle size in soil corresponds with a lower thermal propagation rate. Also, ground thermal regimes vary according to seasons. Ground temperatures are more variable in summer, while air temperatures are more variable in winter. The variability according to different seasons shows that the active layer responds to seasonal climatic variations. Additionally, the active layer also responds to synoptic and diurnal weather events.
- Full Text:
- Date Issued: 2019
- Authors: Masebe, Consliah Tebogo
- Date: 2019
- Subjects: Climatic changes -- Antarctica , Frozen ground -- Research -- Antarctica , Frozen ground -- Thermal properties -- Antarctica , Queen Maud Land , Earth temperature -- Antarctica , Soil temperature -- Antarctica -- Measurement
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95581 , vital:31173
- Description: Research shows that the climate of Antarctica is changing and, it is vital that the change is monitored to understand how it will affect global ecosystems. Since the International Polar Year (IPY) 2007-2008, research in permafrost studies has grown. However, there are still existing gaps that impede complete understanding of Antarctic cold environments and landscape processes. Permafrost has been noted as one of the major controlling factors of the terrestrial ecosystem dynamics in Antarctica. However, the understanding of Antarctic permafrost, when compared to other cryospheric components, is limited, especially its thermal and physical properties, evolution, as well as links to pedogenesis, hydrology, geomorphic dynamics, and responses to global change. This project provided an understanding and insight to over-arching research that evaluates the state and status of permafrost and the active layer in Dronning Maud Land (DML) through examining short-term variations on ground thermal regimes. The main focus is on understanding the influence of synoptic, diurnal and seasonal events on the active layer in 2016. Analysis of available data shows that ground thermal regimes are influenced by variations in air temperature, pressure, wind speed and to some extent, relative humidity. Subsequently, ground thermal regimes also depend on soil physical characteristics including sediment particle size and bulk density. Furthermore, sediment particle size and bulk density have been found to have a great influence on thermal propagation rates as well as active layer depth; the higher the bulk density, the higher the thermal propagation rate and the lower the bulk density, the lower the thermal propagation rate. Conversely, a large proportion of bigger sediment particle size in soil corresponds with a higher thermal propagation rate and a large proportion of smaller sediment particle size in soil corresponds with a lower thermal propagation rate. Also, ground thermal regimes vary according to seasons. Ground temperatures are more variable in summer, while air temperatures are more variable in winter. The variability according to different seasons shows that the active layer responds to seasonal climatic variations. Additionally, the active layer also responds to synoptic and diurnal weather events.
- Full Text:
- Date Issued: 2019
Bioinformatic analysis, isolation and kinetic characterisation of red algae (Gelidium capense) dehydrogenases
- Authors: Gogela, Yanga
- Date: 2019
- Subjects: Bioinformatics Chondrus crispus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19164 , vital:39878
- Description: Lactate and alcohol dehydrogenases have attracted much attention in various industries and scientific research for their ability to produce chirally pure compounds and be assayed for activity using more straightforward and reproducible assay methods. These enzymes have been previously isolated and purified from various plants, animals and microorganisms. So far, the molecular and biochemical properties of enzymes from these dehydrogenase families in red algae are mostly unknown. Red macroalgae have been used for centuries for the treatment of various diseases and as a source of ingredients in the food industry. The aim of this study was to identify genes in the sequenced red algae genomes that encode dehydrogenases, to use bioinformatic tools to confirm that the proteins encoded are dehydrogenases and to isolate and kinetically purify alcohol or lactate dehydrogenase from red algae species found along the coastline of the Eastern Cape Province. A combination of bioinformatics tools, molecular and biochemical techniques were used to identify, purify, and characterise ADH and LDH enzymes. Bioinformatics analysis revealed two alcohol dehydrogenase genes and two hypothetical genes encoding functional domains similar to D-lactate dehydrogenases from other species. The ADH and LDH-like genes shared low sequence identity at the protein level with medium-chain dehydrogenases/reductases (MDRs) and 2-hydroxy acid dehydrogenases, respectively. These two dehydrogenase genes showed a highly conserved NAD-binding motif (Rossmann-fold) similar to many other NAD-dependent dehydrogenases. The ADH and LDH proteins contained no signal peptides and may be located in the cytoplasm. The phylogenetic tree analysis showed that the two ADH genes belonged to cinnamyl and class III alcohol dehydrogenases, whereas the LDHlike genes were grouped with D-lactate dehydrogenases from other organisms. The ADH and LDH gene family showed cis-acting regulatory elements that are mostly involved in stress response and hormonal response. Structural analysis showed that the dehydrogenases 3D structure predicted models comprise of two domains, namely the substrate binding and the coenzyme binding domains that are rich in beta-strands secondary structure elements. The LDH from red algae was purified approximately 4-fold with a specific activity of 0.044 U/mg. The purified LDH enzyme had a molecular weight of approximately 37kDa. The LDH was active across a broad pH range from 5-9 with a pH optimum observed at 7.5. The LDH ii enzyme in red algae exhibits a temperature optimum of 40 ⁰C and heat stability up to 40 ⁰C. Above 50 °C the LDH activity rapidly decreased showing that the LDH in red algae is not thermostable. The LDH enzyme showed a Km value of 0.8 mM and Vmax of 0.0067 mM.min-1 when using sodium pyruvate as a substrate.
- Full Text:
- Date Issued: 2019
- Authors: Gogela, Yanga
- Date: 2019
- Subjects: Bioinformatics Chondrus crispus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19164 , vital:39878
- Description: Lactate and alcohol dehydrogenases have attracted much attention in various industries and scientific research for their ability to produce chirally pure compounds and be assayed for activity using more straightforward and reproducible assay methods. These enzymes have been previously isolated and purified from various plants, animals and microorganisms. So far, the molecular and biochemical properties of enzymes from these dehydrogenase families in red algae are mostly unknown. Red macroalgae have been used for centuries for the treatment of various diseases and as a source of ingredients in the food industry. The aim of this study was to identify genes in the sequenced red algae genomes that encode dehydrogenases, to use bioinformatic tools to confirm that the proteins encoded are dehydrogenases and to isolate and kinetically purify alcohol or lactate dehydrogenase from red algae species found along the coastline of the Eastern Cape Province. A combination of bioinformatics tools, molecular and biochemical techniques were used to identify, purify, and characterise ADH and LDH enzymes. Bioinformatics analysis revealed two alcohol dehydrogenase genes and two hypothetical genes encoding functional domains similar to D-lactate dehydrogenases from other species. The ADH and LDH-like genes shared low sequence identity at the protein level with medium-chain dehydrogenases/reductases (MDRs) and 2-hydroxy acid dehydrogenases, respectively. These two dehydrogenase genes showed a highly conserved NAD-binding motif (Rossmann-fold) similar to many other NAD-dependent dehydrogenases. The ADH and LDH proteins contained no signal peptides and may be located in the cytoplasm. The phylogenetic tree analysis showed that the two ADH genes belonged to cinnamyl and class III alcohol dehydrogenases, whereas the LDHlike genes were grouped with D-lactate dehydrogenases from other organisms. The ADH and LDH gene family showed cis-acting regulatory elements that are mostly involved in stress response and hormonal response. Structural analysis showed that the dehydrogenases 3D structure predicted models comprise of two domains, namely the substrate binding and the coenzyme binding domains that are rich in beta-strands secondary structure elements. The LDH from red algae was purified approximately 4-fold with a specific activity of 0.044 U/mg. The purified LDH enzyme had a molecular weight of approximately 37kDa. The LDH was active across a broad pH range from 5-9 with a pH optimum observed at 7.5. The LDH ii enzyme in red algae exhibits a temperature optimum of 40 ⁰C and heat stability up to 40 ⁰C. Above 50 °C the LDH activity rapidly decreased showing that the LDH in red algae is not thermostable. The LDH enzyme showed a Km value of 0.8 mM and Vmax of 0.0067 mM.min-1 when using sodium pyruvate as a substrate.
- Full Text:
- Date Issued: 2019
The influence of briefing on Eastern Cape government project outcomes
- Authors: Binqela, Lukhanyo
- Date: 2019
- Subjects: Project management -- South Africa -- Eastern Cape , Construction industry -- South Africa -- Eastern Cape Construction industry -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44895 , vital:38186
- Description: South African Government projects are frequently completed with large cost overruns, extended schedules, quality concerns and an increase in emerging contractors making a significant loss in projects they undertake. The construction phase has been the focus of many studies on the causes of unfavourable project outcomes. However, the crucial stages in the construction process that influence the success of a project are the early ones. This is where major decisions that influence the features and form of a project occur. This study, which adopts a case study approach, aims to establish the influence of the brief development process on the outcome of Government projects in the Eastern Cape. Through the reviewed literature and primary data collection, the study aimed at establishing the influence of the brief that is utilised for a need analysis, to define a detailed scope of works, stakeholder engagement and the time management on Eastern Cape Government project outcomes. The Sarah Baartman district was the selected geographical scope of research. Five projects were selected; these included three schools, one emergency medical service facility and one office facility. The study revealed that Eastern Cape Government projects brief development is based on the client department 2013 Published Norms and Standards for state buildings and a need analysis for other stakeholders is not considered. The study further revealed that there is no stakeholder management in government projects; therefore, there is no stakeholder engagement plan during the brief development. The study further revealed that government time management is suboptimal because stakeholder needs are not realised. The research also found that Eastern Cape Government projects do not achieve stakeholder satisfaction and are delivered late. However, some Government projects are able to meet the desired quality and are within budget. The study thus proposes that the Eastern Cape Government projects need to adopt the dynamic brief development process and implement stakeholder management. The brief development process should be an ongoing process extending throughout the project life cycle responding in an innovative manner to emerging stakeholder requirements.
- Full Text:
- Date Issued: 2019
- Authors: Binqela, Lukhanyo
- Date: 2019
- Subjects: Project management -- South Africa -- Eastern Cape , Construction industry -- South Africa -- Eastern Cape Construction industry -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44895 , vital:38186
- Description: South African Government projects are frequently completed with large cost overruns, extended schedules, quality concerns and an increase in emerging contractors making a significant loss in projects they undertake. The construction phase has been the focus of many studies on the causes of unfavourable project outcomes. However, the crucial stages in the construction process that influence the success of a project are the early ones. This is where major decisions that influence the features and form of a project occur. This study, which adopts a case study approach, aims to establish the influence of the brief development process on the outcome of Government projects in the Eastern Cape. Through the reviewed literature and primary data collection, the study aimed at establishing the influence of the brief that is utilised for a need analysis, to define a detailed scope of works, stakeholder engagement and the time management on Eastern Cape Government project outcomes. The Sarah Baartman district was the selected geographical scope of research. Five projects were selected; these included three schools, one emergency medical service facility and one office facility. The study revealed that Eastern Cape Government projects brief development is based on the client department 2013 Published Norms and Standards for state buildings and a need analysis for other stakeholders is not considered. The study further revealed that there is no stakeholder management in government projects; therefore, there is no stakeholder engagement plan during the brief development. The study further revealed that government time management is suboptimal because stakeholder needs are not realised. The research also found that Eastern Cape Government projects do not achieve stakeholder satisfaction and are delivered late. However, some Government projects are able to meet the desired quality and are within budget. The study thus proposes that the Eastern Cape Government projects need to adopt the dynamic brief development process and implement stakeholder management. The brief development process should be an ongoing process extending throughout the project life cycle responding in an innovative manner to emerging stakeholder requirements.
- Full Text:
- Date Issued: 2019
The hepatoprotective capacity of selected natural products from South Africa
- Authors: Reddy, Shanika
- Date: 2019
- Subjects: Liver -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43611 , vital:36929
- Description: Drug-induced liver injury (DILI) is recognized as a significant clinical problem, which may account for up to 50% of all cases of acute liver failure. DILI is initiated by the bioactivation of parent drug molecules to produce chemically reactive metabolites. These reactive intermediates induce mitochondrial dysfunction and oxidative stress leading to glutathione (GSH) depletion and damage to cellular proteins, lipids and nucleic acids, which eventually culminates in necrotic cell death. The principal objective of this study is to establish an in vitro screening platform to identify potential hepatoprotective natural products (plants and mushrooms) from South Africa (SA). Aqueous plant extracts (Cyclopia intermedia, Opuntia ficus indica and Kigelia africana), and aqueous and ethanolic macrofungal extracts (Ganoderma lucidum, Russula capensis, Pleurotus ostreatus and Lenzites elegans) were prepared and screened against HepG2 and VERO cells to assess their safety using Hoechst 33342-PI dual labelling. A drug-induced hepatotoxic model was established, using the dietary supplement menadione (vitamin K3). Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling was used for necrosis, oxidative stress and mitochondrial membrane potential depolarization (ΔΨm) detection, respectively. The accuracy of the hepatoprotection model was confirmed through HepG2 cellbased assays (Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling) that measured the protective effects of natural products against the menadione-induced toxicity, anti-oxidant assays (DPPH, NO, ORAC, CAPe and FRAP) that measured their anti-oxidant potential and enzyme assays (βglucuronidase, carboxylesterase and CYP450 isoform 3A4) that measured their effects on drug metabolism. Silymarin was used as a positive control for each assay. Menadione displayed significant cell death, increased oxidative stress and decreased ΔΨm at an elevated concentration of 100 μM; confirming the hepatotoxicity model, where necroptosis was suspected to be menadione’s cell death mode. Only ethanolic G. lucidum was cytotoxic. All three aqueous plant extracts demonstrated strong anti-oxidant capacities out of all the tested extracts; where C. intermedia displayed the most promising DPPH, NO, ORAC, CAPe and FRAP activity, followed by aqueous G. lucidum. Aqueous plant and ethanolic macrofungal extracts (C. intermedia, O. ficus indica, K. africana, and ethanolic P. ostreatus, R. capensis) displayed decreased menadione-induced ROS production and protected against menadione-induced ΔΨm depolarization, posing them and aqueous G. lucidum potential therapeutic interventions for DILI. Ethanolic L. elegans demonstrated the highest enzyme inhibition for each assay and presented genotoxicity, ruling it out as a therapeutic strategy against DILI. Together these assays addressed several aspects relating to DILI and hepatoprotection, and served as a good starting point in evaluating the therapeutic value of natural products from South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Reddy, Shanika
- Date: 2019
- Subjects: Liver -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43611 , vital:36929
- Description: Drug-induced liver injury (DILI) is recognized as a significant clinical problem, which may account for up to 50% of all cases of acute liver failure. DILI is initiated by the bioactivation of parent drug molecules to produce chemically reactive metabolites. These reactive intermediates induce mitochondrial dysfunction and oxidative stress leading to glutathione (GSH) depletion and damage to cellular proteins, lipids and nucleic acids, which eventually culminates in necrotic cell death. The principal objective of this study is to establish an in vitro screening platform to identify potential hepatoprotective natural products (plants and mushrooms) from South Africa (SA). Aqueous plant extracts (Cyclopia intermedia, Opuntia ficus indica and Kigelia africana), and aqueous and ethanolic macrofungal extracts (Ganoderma lucidum, Russula capensis, Pleurotus ostreatus and Lenzites elegans) were prepared and screened against HepG2 and VERO cells to assess their safety using Hoechst 33342-PI dual labelling. A drug-induced hepatotoxic model was established, using the dietary supplement menadione (vitamin K3). Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling was used for necrosis, oxidative stress and mitochondrial membrane potential depolarization (ΔΨm) detection, respectively. The accuracy of the hepatoprotection model was confirmed through HepG2 cellbased assays (Hoechst 33342- PI, -CellROX® Orange and -TMRE dual labelling) that measured the protective effects of natural products against the menadione-induced toxicity, anti-oxidant assays (DPPH, NO, ORAC, CAPe and FRAP) that measured their anti-oxidant potential and enzyme assays (βglucuronidase, carboxylesterase and CYP450 isoform 3A4) that measured their effects on drug metabolism. Silymarin was used as a positive control for each assay. Menadione displayed significant cell death, increased oxidative stress and decreased ΔΨm at an elevated concentration of 100 μM; confirming the hepatotoxicity model, where necroptosis was suspected to be menadione’s cell death mode. Only ethanolic G. lucidum was cytotoxic. All three aqueous plant extracts demonstrated strong anti-oxidant capacities out of all the tested extracts; where C. intermedia displayed the most promising DPPH, NO, ORAC, CAPe and FRAP activity, followed by aqueous G. lucidum. Aqueous plant and ethanolic macrofungal extracts (C. intermedia, O. ficus indica, K. africana, and ethanolic P. ostreatus, R. capensis) displayed decreased menadione-induced ROS production and protected against menadione-induced ΔΨm depolarization, posing them and aqueous G. lucidum potential therapeutic interventions for DILI. Ethanolic L. elegans demonstrated the highest enzyme inhibition for each assay and presented genotoxicity, ruling it out as a therapeutic strategy against DILI. Together these assays addressed several aspects relating to DILI and hepatoprotection, and served as a good starting point in evaluating the therapeutic value of natural products from South Africa.
- Full Text:
- Date Issued: 2019
The dispersion measure in broadband data from radio pulsars
- Authors: Rammala, Isabella
- Date: 2019
- Subjects: Pulsars , Radio astrophysics , Astrophsyics , Broadband communication systems
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67857 , vital:29157
- Description: Modern day radio telescopes make use of wideband receivers to take advantage of the broadband nature of the radio pulsar emission. We ask how does the use of such broadband pulsar data affect the measured pulsar dispersion measure (DM). Previous works have shown that, although the exact pulsar radio emission processes are not well understood, observations reveal evidence of possible frequency dependence on the emission altitudes in the pulsar magnetosphere, a phenomenon known as the radius-to-frequency mapping (RFM). This frequency dependence due to RFM can be embedded in the dispersive delay of the pulse profiles, normally interpreted as an interstellar effect (DM). Thus we interpret this intrinsic effect as an additional component δDM to the interstellar DM, and investigate how it can be statistically attributed to intrinsic profile evolution, as well as profile scattering. We make use of Monte-Carlo simulations of beam models to simulate realistic pulsar beams of various geometry, from which we generate intrinsic profiles at various frequency bands. The results show that the excess DM due to intrinsic profile evolution is more pronounced at high frequencies, whereas scattering dominates the excess DM at low frequency. The implications of these results are presented with relation to broadband pulsar timing.
- Full Text:
- Date Issued: 2019
- Authors: Rammala, Isabella
- Date: 2019
- Subjects: Pulsars , Radio astrophysics , Astrophsyics , Broadband communication systems
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67857 , vital:29157
- Description: Modern day radio telescopes make use of wideband receivers to take advantage of the broadband nature of the radio pulsar emission. We ask how does the use of such broadband pulsar data affect the measured pulsar dispersion measure (DM). Previous works have shown that, although the exact pulsar radio emission processes are not well understood, observations reveal evidence of possible frequency dependence on the emission altitudes in the pulsar magnetosphere, a phenomenon known as the radius-to-frequency mapping (RFM). This frequency dependence due to RFM can be embedded in the dispersive delay of the pulse profiles, normally interpreted as an interstellar effect (DM). Thus we interpret this intrinsic effect as an additional component δDM to the interstellar DM, and investigate how it can be statistically attributed to intrinsic profile evolution, as well as profile scattering. We make use of Monte-Carlo simulations of beam models to simulate realistic pulsar beams of various geometry, from which we generate intrinsic profiles at various frequency bands. The results show that the excess DM due to intrinsic profile evolution is more pronounced at high frequencies, whereas scattering dominates the excess DM at low frequency. The implications of these results are presented with relation to broadband pulsar timing.
- Full Text:
- Date Issued: 2019
Developing ocean particle tracking tools for cross-disciplinary oceanic research with applications in the Agulhas current region
- Hart-Davis, Michael Geofrey, Backeberg, Björn C
- Authors: Hart-Davis, Michael Geofrey , Backeberg, Björn C
- Date: 2019
- Subjects: Ocean currents , Ocean currents -- Measurement Oceanography Oceanography -- Research -- South Atlantic Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42308 , vital:36644
- Description: Lagrangian ocean analysis is a powerful way to study ocean processes from in-situ observations and numerical model simulations. As numerical modelling capabilities develop and physical mechanisms of the ocean are better understood, the importance of particle trajectory modelling continues to increase. Therefore, developing cross-disciplinary particle trajectory model applications for the Greater Agulhas System is highly relevant due to its potential contribution to scientific studies and operational applications. This thesis presents the results of developing particle trajectory model applications in the Greater Agulhas System towards better understanding the physical mechanisms that drive ocean processes in the region. The model is used in three applications that demonstrate their cross-disciplinary potential. These applications include a search and rescue scenario, the study of ocean dynamics and the study of the fate of juvenile turtles. Introducing spatially and temporally varying stochastic motion to account for the processes not resolved in the ocean surface current products, as well as including more appropriate boundary conditions, were shown to improve the accuracy of virtual drifters in representing the trajectory of a real surface drifter. Next, implementing the spatially and temporally varying stochastic motion in the particle trajectory model and applying it to a search and rescue scenario of a capsized catamaran revealed that including both winds and surface ocean currents in the particle trajectory model allowed for an improved prediction of the capsized vessel’s trajectory. By comparing a pair of real surface drifters with the particle trajectory model and analysing high resolution sea surface temperature (SST) fields it was shown that the formation of an eddy on the Agulhas Plateau combined with the weakening of the core current velocity resulted in enhanced eddycurrent interactions facilitating the separation of the real surface drifter-pair as they passed through this region. Lastly, the particle trajectory model was used to study the importance of including active swimming characteristic when studying the fate of juvenile turtles. It was found that including active swimming resulted in a change in the distribution of juvenile turtles and, therefore, needs to be included to provide a proper understanding of the fate of juvenile turtles in the ocean. With further development and refinement of the particle trajectory model, Lagrangian ocean analysis has the potential to provide valuable information towards improving our understanding of physical and biological ocean processes at a range of spatial and temporal scales with potential operational oceanography applications.
- Full Text:
- Date Issued: 2019
- Authors: Hart-Davis, Michael Geofrey , Backeberg, Björn C
- Date: 2019
- Subjects: Ocean currents , Ocean currents -- Measurement Oceanography Oceanography -- Research -- South Atlantic Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42308 , vital:36644
- Description: Lagrangian ocean analysis is a powerful way to study ocean processes from in-situ observations and numerical model simulations. As numerical modelling capabilities develop and physical mechanisms of the ocean are better understood, the importance of particle trajectory modelling continues to increase. Therefore, developing cross-disciplinary particle trajectory model applications for the Greater Agulhas System is highly relevant due to its potential contribution to scientific studies and operational applications. This thesis presents the results of developing particle trajectory model applications in the Greater Agulhas System towards better understanding the physical mechanisms that drive ocean processes in the region. The model is used in three applications that demonstrate their cross-disciplinary potential. These applications include a search and rescue scenario, the study of ocean dynamics and the study of the fate of juvenile turtles. Introducing spatially and temporally varying stochastic motion to account for the processes not resolved in the ocean surface current products, as well as including more appropriate boundary conditions, were shown to improve the accuracy of virtual drifters in representing the trajectory of a real surface drifter. Next, implementing the spatially and temporally varying stochastic motion in the particle trajectory model and applying it to a search and rescue scenario of a capsized catamaran revealed that including both winds and surface ocean currents in the particle trajectory model allowed for an improved prediction of the capsized vessel’s trajectory. By comparing a pair of real surface drifters with the particle trajectory model and analysing high resolution sea surface temperature (SST) fields it was shown that the formation of an eddy on the Agulhas Plateau combined with the weakening of the core current velocity resulted in enhanced eddycurrent interactions facilitating the separation of the real surface drifter-pair as they passed through this region. Lastly, the particle trajectory model was used to study the importance of including active swimming characteristic when studying the fate of juvenile turtles. It was found that including active swimming resulted in a change in the distribution of juvenile turtles and, therefore, needs to be included to provide a proper understanding of the fate of juvenile turtles in the ocean. With further development and refinement of the particle trajectory model, Lagrangian ocean analysis has the potential to provide valuable information towards improving our understanding of physical and biological ocean processes at a range of spatial and temporal scales with potential operational oceanography applications.
- Full Text:
- Date Issued: 2019
A nutrition education tool for practical application of the food based dietary guidelines for primary school teachers in Nelson Mandela Bay
- Authors: Joubert, Tayla Kate
- Date: 2019
- Subjects: Malnutrition -- South Africa -- Port Elizabeth , Nutrition—Evaluation Nutrition -- Evaluation Nutrition -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/45019 , vital:38226
- Description: The South Africa Food-Based Dietary Guidelines (SAFBDG) was developed to promote better food choices for a healthy lifestyle and are included in the school syllabus. Schools remain viable platforms for nutrition education with teachers playing significant roles, but research has shown that teachers do not necessarily know about the SAFBDG and how to incorporate these into the teaching programme. The aim of this study was to develop a tool in the form of a nutrition education guide for primary school teachers, aimed at the practical application of the SAFBDG, in order to enhance the nutrition knowledge, attitudes and dietary practices of the teachers. A quasi-experimental, one group, quantitative design was employed. Forty-six teachers were conveniently chosen from schools in previously disadvantaged areas of Nelson Mandela Bay. The study design consisted of four phases. Phase one consisted of a pre-test where the teachers’ nutrition knowledge, nutrition attitudes, dietary practices, staff wellness and physical activity were determined by means of a standardised questionnaire. A nutritional assessment was also conducted in phase one. In phase two, the nutrition guide, which was Curriculum Assessment Policy Statement compliant for grades four to seven, was developed. In phase three, the guide was used in a workshop to train the teachers that attended phase one of the study, on how to use the nutrition education guide. In phase four, a post-test was conducted after the training to evaluate the effectiveness of the training and to determine whether there has been an increase in the teachers’ nutrition knowledge. Data from the questionnaires were analysed on Microsoft Excel 2016 MSO (16.0.4639.1000). Ethical approval for this study was obtained from the Faculty Postgraduate Studies Committee (FPGSC) of the Faculty of Health Sciences, Nelson Mandela University (Ethics clearance reference number: H18-HEA-DIET-005) and all ethical principles were upheld according to the Belmont report and the Declaration of Helsinki. Results of the research 46 teachers who participated 36 (78 %) were obese. The mean waist circumference and waist-to-hip ratio was 109.99 and 0.887 respectively (± 17.32 and ± 0.089). The teachers obtained a relatively high mean overall score in the pre-test of 69 % (± 10.78). Only 42 % of the teachers had heard of the SAFBDG before the study. There was an overall statistical significant increase in knowledge of 6 % (p = 0.03) from the pre-test to the post-test. The dietary practice was obtained through a food frequency questionnaire (FFQ), which showed under-reporting. The most neglected food groups were legumes, dairy and vegetables/ fruit. Hypertension was the highest self-reported condition, with just under a quarter of the teachers having hypertension (high blood pressure). There was no statistical significance between the teachers’ BMI and their nutrition knowledge as well as no statistical significance between their BMI and their physical activity level. Even though the teachers obtained a relatively high mean overall score in their pre-test, there were still gaps in their nutrition knowledge. These gaps in the teachers’ knowledge results in insufficient nutrition knowledge being provided to the learners, leading to poor dietary practices and misconceptions regarding different foods among the learners as well as the teachers. By providing training for the teachers, it will not only improve their nutrition knowledge but potentially also help to improve their lifestyle. With enhanced nutrition knowledge, the teachers can communicate sufficient information to their learners. The DoBE need to advocate for a healthier school environment in which the SAFBDG are implemented more extensively in the curriculum as well as part of school food policies.
- Full Text:
- Date Issued: 2019
- Authors: Joubert, Tayla Kate
- Date: 2019
- Subjects: Malnutrition -- South Africa -- Port Elizabeth , Nutrition—Evaluation Nutrition -- Evaluation Nutrition -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/45019 , vital:38226
- Description: The South Africa Food-Based Dietary Guidelines (SAFBDG) was developed to promote better food choices for a healthy lifestyle and are included in the school syllabus. Schools remain viable platforms for nutrition education with teachers playing significant roles, but research has shown that teachers do not necessarily know about the SAFBDG and how to incorporate these into the teaching programme. The aim of this study was to develop a tool in the form of a nutrition education guide for primary school teachers, aimed at the practical application of the SAFBDG, in order to enhance the nutrition knowledge, attitudes and dietary practices of the teachers. A quasi-experimental, one group, quantitative design was employed. Forty-six teachers were conveniently chosen from schools in previously disadvantaged areas of Nelson Mandela Bay. The study design consisted of four phases. Phase one consisted of a pre-test where the teachers’ nutrition knowledge, nutrition attitudes, dietary practices, staff wellness and physical activity were determined by means of a standardised questionnaire. A nutritional assessment was also conducted in phase one. In phase two, the nutrition guide, which was Curriculum Assessment Policy Statement compliant for grades four to seven, was developed. In phase three, the guide was used in a workshop to train the teachers that attended phase one of the study, on how to use the nutrition education guide. In phase four, a post-test was conducted after the training to evaluate the effectiveness of the training and to determine whether there has been an increase in the teachers’ nutrition knowledge. Data from the questionnaires were analysed on Microsoft Excel 2016 MSO (16.0.4639.1000). Ethical approval for this study was obtained from the Faculty Postgraduate Studies Committee (FPGSC) of the Faculty of Health Sciences, Nelson Mandela University (Ethics clearance reference number: H18-HEA-DIET-005) and all ethical principles were upheld according to the Belmont report and the Declaration of Helsinki. Results of the research 46 teachers who participated 36 (78 %) were obese. The mean waist circumference and waist-to-hip ratio was 109.99 and 0.887 respectively (± 17.32 and ± 0.089). The teachers obtained a relatively high mean overall score in the pre-test of 69 % (± 10.78). Only 42 % of the teachers had heard of the SAFBDG before the study. There was an overall statistical significant increase in knowledge of 6 % (p = 0.03) from the pre-test to the post-test. The dietary practice was obtained through a food frequency questionnaire (FFQ), which showed under-reporting. The most neglected food groups were legumes, dairy and vegetables/ fruit. Hypertension was the highest self-reported condition, with just under a quarter of the teachers having hypertension (high blood pressure). There was no statistical significance between the teachers’ BMI and their nutrition knowledge as well as no statistical significance between their BMI and their physical activity level. Even though the teachers obtained a relatively high mean overall score in their pre-test, there were still gaps in their nutrition knowledge. These gaps in the teachers’ knowledge results in insufficient nutrition knowledge being provided to the learners, leading to poor dietary practices and misconceptions regarding different foods among the learners as well as the teachers. By providing training for the teachers, it will not only improve their nutrition knowledge but potentially also help to improve their lifestyle. With enhanced nutrition knowledge, the teachers can communicate sufficient information to their learners. The DoBE need to advocate for a healthier school environment in which the SAFBDG are implemented more extensively in the curriculum as well as part of school food policies.
- Full Text:
- Date Issued: 2019
Red tape in upgrading of informal settlements in Nelson Mandela Bay
- Authors: Mangezi, Wilfred
- Date: 2019
- Subjects: Housing development -- South Africa -- Nelson Mandela Bay Municipality , Squatter settlements -- South Africa -- Nelson Mandela Bay Municipality Squatters -- South Africa -- Nelson Mandela Bay Municipality Housing -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/33375 , vital:32745
- Description: Even though there is general acknowledgement of the existence of red tape in low cost housing, very little effort has been made to seek-out its underlying causes. The purpose of this study was to investigate red tape in specific Informal Settlement Upgrading Programme (ISUP) developments within the Nelson Mandela Bay, to uncover the underlying causes of red tape and ultimately suggest possible remedies to reduce red tape and its adverse effects. Administrative red tape in ISUP projects is hampering the government’s efforts to improve informal settlement dwellers’ standard of living, as evidenced by the slow pace of housing delivery to such intended beneficiaries. Furthermore, red tape also causes frustration to Small, Medium, and Micro Enterprises (SMME’s) that are involved in the low-cost housing delivery value chain who suffer cash flow problems due to delays incurred from payment of their services by the local authority. This hindrance does not spare the majority of municipal employees whose roles are dependent on the performance of other departments. Of great concern are the residents within the municipality who have developed a culture of expressing their frustration caused by such delays through violent demonstrations so much to the detriment of the peaceful environment that has over time characterised this friendly tourist destination of South Africa. Applying a qualitative research strategy, the researcher undertook data collection through document review and face to face interviews from targeted respondents across various departments within and outside the municipality that deals with ISUP developments. The study revealed that, red tape in ISUP projects is a result of a variety of factors which include; inept internal management procedures, misinterpretation of legislation, silo mentality and lack of capacity in housing delivery. Thus the rules, legislation and procedures prevailing are failing to keep pace with the changing macro environment. To reduce the impact of red tape the researcher believes that it would be of paramount importance for the NMBM to consider; realignment of their internal procedures to counter the pressure posed by the residents, integrate project teams or functional departments dealing with housing, engage beneficiaries from the onset of the projects, invest in training staff and acquisition of new technology. The core of reducing red tape lies in upgrading of rules and administrative procedures in dealing with ISUP projects within the municipality so as to adopt to the dynamism that characterise the built environment.
- Full Text:
- Date Issued: 2019
- Authors: Mangezi, Wilfred
- Date: 2019
- Subjects: Housing development -- South Africa -- Nelson Mandela Bay Municipality , Squatter settlements -- South Africa -- Nelson Mandela Bay Municipality Squatters -- South Africa -- Nelson Mandela Bay Municipality Housing -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/33375 , vital:32745
- Description: Even though there is general acknowledgement of the existence of red tape in low cost housing, very little effort has been made to seek-out its underlying causes. The purpose of this study was to investigate red tape in specific Informal Settlement Upgrading Programme (ISUP) developments within the Nelson Mandela Bay, to uncover the underlying causes of red tape and ultimately suggest possible remedies to reduce red tape and its adverse effects. Administrative red tape in ISUP projects is hampering the government’s efforts to improve informal settlement dwellers’ standard of living, as evidenced by the slow pace of housing delivery to such intended beneficiaries. Furthermore, red tape also causes frustration to Small, Medium, and Micro Enterprises (SMME’s) that are involved in the low-cost housing delivery value chain who suffer cash flow problems due to delays incurred from payment of their services by the local authority. This hindrance does not spare the majority of municipal employees whose roles are dependent on the performance of other departments. Of great concern are the residents within the municipality who have developed a culture of expressing their frustration caused by such delays through violent demonstrations so much to the detriment of the peaceful environment that has over time characterised this friendly tourist destination of South Africa. Applying a qualitative research strategy, the researcher undertook data collection through document review and face to face interviews from targeted respondents across various departments within and outside the municipality that deals with ISUP developments. The study revealed that, red tape in ISUP projects is a result of a variety of factors which include; inept internal management procedures, misinterpretation of legislation, silo mentality and lack of capacity in housing delivery. Thus the rules, legislation and procedures prevailing are failing to keep pace with the changing macro environment. To reduce the impact of red tape the researcher believes that it would be of paramount importance for the NMBM to consider; realignment of their internal procedures to counter the pressure posed by the residents, integrate project teams or functional departments dealing with housing, engage beneficiaries from the onset of the projects, invest in training staff and acquisition of new technology. The core of reducing red tape lies in upgrading of rules and administrative procedures in dealing with ISUP projects within the municipality so as to adopt to the dynamism that characterise the built environment.
- Full Text:
- Date Issued: 2019