Causes of road projects’ delays: a case of Blantyre
- Authors: Mwamvani, Henry Duncan John
- Date: 2019
- Subjects: Construction industry -- Management , Engineering -- Management Project management Building -- Planning Building -- Superintendance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41719 , vital:36575
- Description: The Construction Industry (CI) is recognised as a formidable sector that has the potential of facilitating the growth and development of a nation’s economy by providing the necessary infrastructure that is required to spur the growth of other industries. In many countries, such as Malawi, the city councils (CCs) also influence the implementation and management of such infrastructure as mandated by the Malawi Local Government Act (1998). Successful projects should be implemented in such a manner that completion of the projects is within the golden triangle of cost, time and quality. This implies that projects are completed within the planned budget, stipulated time and specified quality. City Councils in Malawi, however, face various challenges in their implementation of infrastructure projects leading to delayed project completion, resulting in extended project implementation periods. This study aimed at finding the causes of road projects construction delays in Blantyre City Council, (BCC) which is one of the four CCs in Malawi, the second largest and the commercial capital. The study followed a qualitative research method using a case study approach. This study combined in-depth, face-to-face interviews of identified stakeholders with general routine work observations and project document gathering to collect the primary data while secondary data was obtained from books, research journal articles, government documents, unpublished theses, some international organisation reports, general internet information and other academic related sources of relevant information. The participants included council representatives (council service committee chairperson, secretariat management staff), contractors’ representatives and consultants’ representatives. The participants were chosen using a non-probability sampling method of purposive and snowball selection, targeting their involvement in the previous and/or the current project implementation cycles. The study also involved visiting some of the ongoing and completed projects and collecting project photographs. The findings from the case study revealed challenges the council faced due to a shortage of engineers in conducting detailed proposed projects surveys resulting in incomplete project scope definition (detailed designs) on some projects, before the procurement of contractors as the major cause of project construction delays. Other factors that were identified were: service providers delaying the removal of existing public utility infrastructure from project sites, inclement weather and the client delays in issuing instructions to the contractors during the implementation of the projects. Another factor was the shortage of construction equipment and construction materials by some contractors. Based on the research findings, the main recommendation is to increase the number of technical employees, especially engineers and other key technical staff such as quantity surveyors by improving the employees’ conditions of service. Improving the service conditions will attract and retain the right quality and quantity of technical employees to undertake the management of the construction projects. Alternatively, all positions for professionals who are deemed as scarce or hard to maintain could be placed on a contract basis, renewable after a period of two to three years. This would be able to attract those professionals who are ready to offer their expertise for a certain period but may not necessarily want to work until the government mandatory retirement. This will be in addition to the engagement of external project consultants to assist in project management, which the council started implementing in 2017. As for the delay in the removal of utility services infrastructure on proposed project sites, the client needs to commence with the process early in the planning and procurement process before handing over the project sites to the contractors. General contractor delay causes can be minimised by raising the selection criteria of contractors to flush out as well as black-listing incompetent contractors.
- Full Text:
- Date Issued: 2019
- Authors: Mwamvani, Henry Duncan John
- Date: 2019
- Subjects: Construction industry -- Management , Engineering -- Management Project management Building -- Planning Building -- Superintendance
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/41719 , vital:36575
- Description: The Construction Industry (CI) is recognised as a formidable sector that has the potential of facilitating the growth and development of a nation’s economy by providing the necessary infrastructure that is required to spur the growth of other industries. In many countries, such as Malawi, the city councils (CCs) also influence the implementation and management of such infrastructure as mandated by the Malawi Local Government Act (1998). Successful projects should be implemented in such a manner that completion of the projects is within the golden triangle of cost, time and quality. This implies that projects are completed within the planned budget, stipulated time and specified quality. City Councils in Malawi, however, face various challenges in their implementation of infrastructure projects leading to delayed project completion, resulting in extended project implementation periods. This study aimed at finding the causes of road projects construction delays in Blantyre City Council, (BCC) which is one of the four CCs in Malawi, the second largest and the commercial capital. The study followed a qualitative research method using a case study approach. This study combined in-depth, face-to-face interviews of identified stakeholders with general routine work observations and project document gathering to collect the primary data while secondary data was obtained from books, research journal articles, government documents, unpublished theses, some international organisation reports, general internet information and other academic related sources of relevant information. The participants included council representatives (council service committee chairperson, secretariat management staff), contractors’ representatives and consultants’ representatives. The participants were chosen using a non-probability sampling method of purposive and snowball selection, targeting their involvement in the previous and/or the current project implementation cycles. The study also involved visiting some of the ongoing and completed projects and collecting project photographs. The findings from the case study revealed challenges the council faced due to a shortage of engineers in conducting detailed proposed projects surveys resulting in incomplete project scope definition (detailed designs) on some projects, before the procurement of contractors as the major cause of project construction delays. Other factors that were identified were: service providers delaying the removal of existing public utility infrastructure from project sites, inclement weather and the client delays in issuing instructions to the contractors during the implementation of the projects. Another factor was the shortage of construction equipment and construction materials by some contractors. Based on the research findings, the main recommendation is to increase the number of technical employees, especially engineers and other key technical staff such as quantity surveyors by improving the employees’ conditions of service. Improving the service conditions will attract and retain the right quality and quantity of technical employees to undertake the management of the construction projects. Alternatively, all positions for professionals who are deemed as scarce or hard to maintain could be placed on a contract basis, renewable after a period of two to three years. This would be able to attract those professionals who are ready to offer their expertise for a certain period but may not necessarily want to work until the government mandatory retirement. This will be in addition to the engagement of external project consultants to assist in project management, which the council started implementing in 2017. As for the delay in the removal of utility services infrastructure on proposed project sites, the client needs to commence with the process early in the planning and procurement process before handing over the project sites to the contractors. General contractor delay causes can be minimised by raising the selection criteria of contractors to flush out as well as black-listing incompetent contractors.
- Full Text:
- Date Issued: 2019
Chacma baboons (papio ursinus) influence zoogeomorphic processes in the Karoo through rock movement
- Authors: Maré, Celesté
- Date: 2019
- Subjects: Geomorphology -- South Africa -- Eastern Cape , Biogeomorphology Geology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40966 , vital:36278
- Description: Animals sculpt landforms by physically altering the substrate. The field of zoogeomorphology has developed to explicitly consider the role of animals as geomorphic agents. Many digging and burrowing animals are then considered zoogeomorphic agents. While the significance of soil disturbing species is well established, geomorphic impacts are rarely quantified for rock transporting species. Chacma baboons (Papio ursinus, hereafter baboon), a widespread and abundant primate, have the potential to act as a zoogeomorphic agent through their purposeful rock displacement while foraging. With this study I assessed the role of baboons as rock rolling agents by demonstrating that baboons roll rocks to search for and feed on organisms beneath, quantifying the extent of this process, and establishing the preferences of baboons for rock features. Observations from a troop of wild baboons showed that rock rolling is an important component of the daily foraging routine of baboons, and confirmed that baboons roll rocks to feed on the organisms beneath. Baboon rock movement was extensive, with potentially tons of rock material moved across many hectares over one year in some habitats. The distance of this rock movement was influenced by a combination of rock mass, rock shape and the slope of the landscape. Baboons showed clear preferences for the rocks they rolled in terms of shape and size, with rock size being an important driver of baboon rock rolling. With this study I show that the chacma baboon is an important rock moving species, with the potential to impact a range of ecological and geological processes. As such, baboons may serve as a keystone species as they are the only species in this environment to intentionally move rocks in this way. However, because baboons are considered pests and are widely persecuted, their role in zoogeomorphic processes are vulnerable to being lost.
- Full Text:
- Date Issued: 2019
- Authors: Maré, Celesté
- Date: 2019
- Subjects: Geomorphology -- South Africa -- Eastern Cape , Biogeomorphology Geology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40966 , vital:36278
- Description: Animals sculpt landforms by physically altering the substrate. The field of zoogeomorphology has developed to explicitly consider the role of animals as geomorphic agents. Many digging and burrowing animals are then considered zoogeomorphic agents. While the significance of soil disturbing species is well established, geomorphic impacts are rarely quantified for rock transporting species. Chacma baboons (Papio ursinus, hereafter baboon), a widespread and abundant primate, have the potential to act as a zoogeomorphic agent through their purposeful rock displacement while foraging. With this study I assessed the role of baboons as rock rolling agents by demonstrating that baboons roll rocks to search for and feed on organisms beneath, quantifying the extent of this process, and establishing the preferences of baboons for rock features. Observations from a troop of wild baboons showed that rock rolling is an important component of the daily foraging routine of baboons, and confirmed that baboons roll rocks to feed on the organisms beneath. Baboon rock movement was extensive, with potentially tons of rock material moved across many hectares over one year in some habitats. The distance of this rock movement was influenced by a combination of rock mass, rock shape and the slope of the landscape. Baboons showed clear preferences for the rocks they rolled in terms of shape and size, with rock size being an important driver of baboon rock rolling. With this study I show that the chacma baboon is an important rock moving species, with the potential to impact a range of ecological and geological processes. As such, baboons may serve as a keystone species as they are the only species in this environment to intentionally move rocks in this way. However, because baboons are considered pests and are widely persecuted, their role in zoogeomorphic processes are vulnerable to being lost.
- Full Text:
- Date Issued: 2019
Characterization and antibiogram fingerprints of Enterobacteriaceae and Listeria monocytogenes in irrigation water and agricultural soil samples collected from Amathole and Chris Hani District Municipalities in the Eastern Cape Province, South Africa
- Authors: Iwu, Chidozie Declan
- Date: 2019
- Subjects: Listeria monocytogenes Enterobacteriaceae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17187 , vital:40864
- Description: Characterization and antibiogram fingerprints of Enterobacteriaceae and Listeria monocytogenes in irrigation water and agricultural soil samples collected from Amathole and Chris Hani District Municipalities in the Eastern Cape Province, South Africa
- Full Text:
- Date Issued: 2019
- Authors: Iwu, Chidozie Declan
- Date: 2019
- Subjects: Listeria monocytogenes Enterobacteriaceae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17187 , vital:40864
- Description: Characterization and antibiogram fingerprints of Enterobacteriaceae and Listeria monocytogenes in irrigation water and agricultural soil samples collected from Amathole and Chris Hani District Municipalities in the Eastern Cape Province, South Africa
- Full Text:
- Date Issued: 2019
Chitin hydrolysis with chitinolytic enzymes for the production of chitooligomers with antimicrobial properties
- Authors: Oree, Glynis
- Date: 2019
- Subjects: Chitin -- Biotechnology , Enzymes -- Biotechnology , Hydrolysis , Chitooligomers -- Biotechnology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67887 , vital:29165
- Description: There are many diseases and illnesses in the world that require new drug treatments and chitin has been shown to produce chitooligomeric derivatives which exhibit promising antimicrobial and immune-enhancing properties. However, the rate-limiting step is associated with the high recalcitrance of chitinous substrates, and low hydrolytic activities of chitinolytic enzymes, resulting in low product release. To improve and create a more sustainable and economical process, enhancing chitin hydrolysis through various treatment procedures is essential for obtaining high enzyme hydrolysis rates, resulting in a higher yield of chitooligomers (CHOS). In literature, pre-treatment of insoluble biomass is generally associated with an increase in accessibility of the carbohydrate to hydrolytic enzymes, thus generating more products. The first part of this study investigated the effect of alkali- (NaOH) and acid pre-treatments (HCl and phosphoric acid) on chitin biomass, and chemical and morphological modifications were assessed by the employment of scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray spectrometery (EDX) and x-ray diffraction (XRD). Data obtained confirmed that pre-treated substrates were more chemically and morphologically modified. These results confirmed the fact that pre-treatment of chitin disrupts the structure of the biomass, rendering the polymer more accessible for enzymatic hydrolysis. The commercial chitinases from Bacillus cereus and Streptomyces griseus (CHB and CHS) are costly. Bio-prospecting for other chitin-degrading enzymes from alternate sources such as Oidiodendron maius, or the recombinant expression of CHOS, was a more economically feasible avenue. The chit1 gene from Thermomyces lanuginosus, expressed in Pichia pastoris, produced a large range CHOS with a degree of polymerisation (DP) ranging from 1 to above 6. TLC analysis showed that O. maius exhibited chitin-degrading properties by producing CHOS with a DP length of 1 to 3. These two sources were therefore successful in producing chitin-degrading enzymes. The physico-chemical properties of commercial (CHB and CHS) and expressed (Chit1) chitinolytic enzymes were investigated, to determine under which biochemical conditions and on which type of biomass they can function on optimally, for the production of value-added products such as CHOS. Substrate affinity assays were conducted on the un-treated and pre-treated biomass. TLC revealed that chitosan hydrolysis by the commercial chitinases produced the largest range of CHOS with a DP length ranging from 1 to 6. A range of temperatures (35-90oC) were investigated and CHB, CHS and Chit1 displayed optimum activities at 50, 40 and 45 oC, respectively. Thermostability studies that were conducted at 37 and 50oC revealed that CHB and CHS were most stable at 37oC. Chit1 showed great thermostablity at both temperatures, rendering this enzyme suitable for industrial processes at high temperatures. pH optima studies demonstrated that the pH optima for CHB, CHS and Chit1 was at a pH of 5.0, with specific activities of 33.459, 46.2 and 5.776 μmol/h/mg, respectively. The chain cleaving patterns of the commercial enzymes were determined and exo-chitinase activity was exhibited, due to the production of CHOS that were predominantly of a DP length of 2. Enzyme binary synergy studies were conducted with commercial chitinases (CHB and CHS) on colloidal chitin. Studies illustrated that the simultaneous combination of CHB 75%: CHS 25% produced the highest specific activity (3.526 μmol/h/mg), with no synergy. TLC analysis of this enzyme combination over time revealed that predominantly chitobiose was produced. This suggested that the substrate crystallinity and morphology played an important role in the way the enzymes cleaved the carbohydrate. Since CHOS have shown great promise for their antimicrobial properties, the CHOS generated from the chitinous substrates were tested for antimicrobial properties on Bacillus subtilis, Escherichia coli, Klebsiella and Staphlococcus aureus. This study revealed that certain CHOS produced have inhibitory effects on certain bacteria and could potentially be used in the pharamceutical or medical industries. In conclusion, this study revealed that chitinases can be produced and found in alternate sources and be used for the hydrolysis of chitinous biomass in a more sustainabe and economically viable manner. The chitinases investigated (CHB, CHS and Chit1) exhibited different cleaving patterns of the chitinous substrates due to the chemical and morphological properties of the biomass. CHOS produced from chitinous biomass exhibited some inhibitory effects on bacterial growth and show potential for use in the medical industry.
- Full Text:
- Date Issued: 2019
- Authors: Oree, Glynis
- Date: 2019
- Subjects: Chitin -- Biotechnology , Enzymes -- Biotechnology , Hydrolysis , Chitooligomers -- Biotechnology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67887 , vital:29165
- Description: There are many diseases and illnesses in the world that require new drug treatments and chitin has been shown to produce chitooligomeric derivatives which exhibit promising antimicrobial and immune-enhancing properties. However, the rate-limiting step is associated with the high recalcitrance of chitinous substrates, and low hydrolytic activities of chitinolytic enzymes, resulting in low product release. To improve and create a more sustainable and economical process, enhancing chitin hydrolysis through various treatment procedures is essential for obtaining high enzyme hydrolysis rates, resulting in a higher yield of chitooligomers (CHOS). In literature, pre-treatment of insoluble biomass is generally associated with an increase in accessibility of the carbohydrate to hydrolytic enzymes, thus generating more products. The first part of this study investigated the effect of alkali- (NaOH) and acid pre-treatments (HCl and phosphoric acid) on chitin biomass, and chemical and morphological modifications were assessed by the employment of scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray spectrometery (EDX) and x-ray diffraction (XRD). Data obtained confirmed that pre-treated substrates were more chemically and morphologically modified. These results confirmed the fact that pre-treatment of chitin disrupts the structure of the biomass, rendering the polymer more accessible for enzymatic hydrolysis. The commercial chitinases from Bacillus cereus and Streptomyces griseus (CHB and CHS) are costly. Bio-prospecting for other chitin-degrading enzymes from alternate sources such as Oidiodendron maius, or the recombinant expression of CHOS, was a more economically feasible avenue. The chit1 gene from Thermomyces lanuginosus, expressed in Pichia pastoris, produced a large range CHOS with a degree of polymerisation (DP) ranging from 1 to above 6. TLC analysis showed that O. maius exhibited chitin-degrading properties by producing CHOS with a DP length of 1 to 3. These two sources were therefore successful in producing chitin-degrading enzymes. The physico-chemical properties of commercial (CHB and CHS) and expressed (Chit1) chitinolytic enzymes were investigated, to determine under which biochemical conditions and on which type of biomass they can function on optimally, for the production of value-added products such as CHOS. Substrate affinity assays were conducted on the un-treated and pre-treated biomass. TLC revealed that chitosan hydrolysis by the commercial chitinases produced the largest range of CHOS with a DP length ranging from 1 to 6. A range of temperatures (35-90oC) were investigated and CHB, CHS and Chit1 displayed optimum activities at 50, 40 and 45 oC, respectively. Thermostability studies that were conducted at 37 and 50oC revealed that CHB and CHS were most stable at 37oC. Chit1 showed great thermostablity at both temperatures, rendering this enzyme suitable for industrial processes at high temperatures. pH optima studies demonstrated that the pH optima for CHB, CHS and Chit1 was at a pH of 5.0, with specific activities of 33.459, 46.2 and 5.776 μmol/h/mg, respectively. The chain cleaving patterns of the commercial enzymes were determined and exo-chitinase activity was exhibited, due to the production of CHOS that were predominantly of a DP length of 2. Enzyme binary synergy studies were conducted with commercial chitinases (CHB and CHS) on colloidal chitin. Studies illustrated that the simultaneous combination of CHB 75%: CHS 25% produced the highest specific activity (3.526 μmol/h/mg), with no synergy. TLC analysis of this enzyme combination over time revealed that predominantly chitobiose was produced. This suggested that the substrate crystallinity and morphology played an important role in the way the enzymes cleaved the carbohydrate. Since CHOS have shown great promise for their antimicrobial properties, the CHOS generated from the chitinous substrates were tested for antimicrobial properties on Bacillus subtilis, Escherichia coli, Klebsiella and Staphlococcus aureus. This study revealed that certain CHOS produced have inhibitory effects on certain bacteria and could potentially be used in the pharamceutical or medical industries. In conclusion, this study revealed that chitinases can be produced and found in alternate sources and be used for the hydrolysis of chitinous biomass in a more sustainabe and economically viable manner. The chitinases investigated (CHB, CHS and Chit1) exhibited different cleaving patterns of the chitinous substrates due to the chemical and morphological properties of the biomass. CHOS produced from chitinous biomass exhibited some inhibitory effects on bacterial growth and show potential for use in the medical industry.
- Full Text:
- Date Issued: 2019
Climatic suitability of Dichrorampha odorata Brown and Zachariades (Lepidoptera: Tortricidae), a shoot-boring moth for the biological control of Chromolaena odorata (L.) R.M. King and H. Robinson (Asteraceae) in South Africa
- Authors: Nqayi, Slindile Brightness
- Date: 2019
- Subjects: CLIMEX , Chromolaena odorata -- Biological control -- South Africa , Tortricidae -- South Africa , Bioclimatology -- Software
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92208 , vital:30681
- Description: Biological control using natural enemies introduced from the native range is an integral component of the management of Chromolaena odorata, a serious invader in the eastern regions of South Africa. A number of biological control agents for C. odorata have been released in South Africa, and one of them, Dichrorampha odorata, has failed to establish. To understand if D. odorata failed to establish due to climate incompatibility, its thermal physiology was investigated. Thermal tolerance data were used to determine the developmental thresholds and number of generations that D. odorata is capable of going through in South Africa per year. These predictions were generated using CLIMEX temperature data and the degree-day parameters K and t0. Developmental time decreased with increasing temperatures ranging from 20 °C to 30°C, with immature stages not able to complete development at 18°C and 32°C. The developmental threshold, to, was determined as 8.45 °C with 872.4 degree-days required to complete development (K), indicating that D. odorata is capable of producing a maximum number of 6.5 generations per year in South Africa. The CLIMEX data indicated that the east coast regions of South Africa, which are the heaviest invaded areas by C. odorata in South Africa, were climatically most suitable for D. odorata to. D. odorata lower (LLT50) and upper (ULT50) lethal temperatures were -4.5°C and 39.64°C for larvae and 1.83 and 41.02°C for adults, and D. odorata adults were able to maintain locomotory functioning at 4.4 to 43.7°C, respectively. Acclimation at low and high temperatures indicate that when D. odorata was kept at a lower temperature of 20°C for 7 days, it became tolerant to warmer and cooler temperatures (1.95 and 44.41°C) when compared to D. odorata reared at 25°C (3.36 and 43.67°C) and 30°C (5.92 and 42.93°C). Dichrorampha odorata is therefore climatically suitable for release and should establish in South Africa to control C. odorata. The establishment and persistence of D. odorata will not be limited by climatic conditions but rather the distribution of its host weed, C. odorata in South Africa. Also, this study presents a decision-making protocol for the release of D. odorata to allow better performance in the field.
- Full Text:
- Date Issued: 2019
- Authors: Nqayi, Slindile Brightness
- Date: 2019
- Subjects: CLIMEX , Chromolaena odorata -- Biological control -- South Africa , Tortricidae -- South Africa , Bioclimatology -- Software
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92208 , vital:30681
- Description: Biological control using natural enemies introduced from the native range is an integral component of the management of Chromolaena odorata, a serious invader in the eastern regions of South Africa. A number of biological control agents for C. odorata have been released in South Africa, and one of them, Dichrorampha odorata, has failed to establish. To understand if D. odorata failed to establish due to climate incompatibility, its thermal physiology was investigated. Thermal tolerance data were used to determine the developmental thresholds and number of generations that D. odorata is capable of going through in South Africa per year. These predictions were generated using CLIMEX temperature data and the degree-day parameters K and t0. Developmental time decreased with increasing temperatures ranging from 20 °C to 30°C, with immature stages not able to complete development at 18°C and 32°C. The developmental threshold, to, was determined as 8.45 °C with 872.4 degree-days required to complete development (K), indicating that D. odorata is capable of producing a maximum number of 6.5 generations per year in South Africa. The CLIMEX data indicated that the east coast regions of South Africa, which are the heaviest invaded areas by C. odorata in South Africa, were climatically most suitable for D. odorata to. D. odorata lower (LLT50) and upper (ULT50) lethal temperatures were -4.5°C and 39.64°C for larvae and 1.83 and 41.02°C for adults, and D. odorata adults were able to maintain locomotory functioning at 4.4 to 43.7°C, respectively. Acclimation at low and high temperatures indicate that when D. odorata was kept at a lower temperature of 20°C for 7 days, it became tolerant to warmer and cooler temperatures (1.95 and 44.41°C) when compared to D. odorata reared at 25°C (3.36 and 43.67°C) and 30°C (5.92 and 42.93°C). Dichrorampha odorata is therefore climatically suitable for release and should establish in South Africa to control C. odorata. The establishment and persistence of D. odorata will not be limited by climatic conditions but rather the distribution of its host weed, C. odorata in South Africa. Also, this study presents a decision-making protocol for the release of D. odorata to allow better performance in the field.
- Full Text:
- Date Issued: 2019
Comparing organic and conventional farming systems in George, South Africa
- Authors: Swanepoel, Marike
- Date: 2019
- Subjects: Organic farming -- South Africa -- George , Sustainable agriculture -- South Africa -- George Agricultural systems -- South Africa -- George
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43946 , vital:37086
- Description: This study presents some of the findings of a long-term comparative study at the Nelson Mandela University George campus which started in 2014. This research compares the differences in crop yields and soil fertility under conventional and organic farming systems. Although previous research that was conducted will be presented briefly, the main focus of this dissertation is to report on the research results generated during the 2016/17 and 2017/18 cropping seasons. The baseline study (indicator measurements) was done in 2014 and investigated soil fertility before the different farming systems were implemented. The rapid increase in human population threatens food security, especially in developing countries. Climate change together with the degradation of soil and other natural resources due to high-input industrial farming, provide further challenges in terms of agriculture and future food security. Agricultural production in South Africa faces three obstacles: water scarcity, infertile soils and poor institutional support. Therefore, regenerative and sustainable agriculture practices such as organic farming, are increasingly being promoted as an alternative to conventional farming systems in southern Africa. What is the best way of farming? This is the question every farmer is confronted with. Some say organic whilst others say conventional, but how do we determine this? What is the role of crop rotation in pest management, soil fertility and crop yield? So we set up the research to compare the two farming systems so that decisions can be based on sound scientific findings. Results showed a significant increase in the case of the organic yield in season 2016/17 for cabbage and in both seasons (2016/17 & 2017/18) for cowpea and sweet potato, proving that organic farming yields can increase over time. Soil fertility changes from the baseline year (2014) till the end of season 2017/18 were compared. Overall organic farming systems showed very promising results with higher levels of soil pH followed by a significant increase in important soil nutrients (P, K & C) compared to conventional systems. Crop rotation also had positive effects.
- Full Text:
- Date Issued: 2019
- Authors: Swanepoel, Marike
- Date: 2019
- Subjects: Organic farming -- South Africa -- George , Sustainable agriculture -- South Africa -- George Agricultural systems -- South Africa -- George
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43946 , vital:37086
- Description: This study presents some of the findings of a long-term comparative study at the Nelson Mandela University George campus which started in 2014. This research compares the differences in crop yields and soil fertility under conventional and organic farming systems. Although previous research that was conducted will be presented briefly, the main focus of this dissertation is to report on the research results generated during the 2016/17 and 2017/18 cropping seasons. The baseline study (indicator measurements) was done in 2014 and investigated soil fertility before the different farming systems were implemented. The rapid increase in human population threatens food security, especially in developing countries. Climate change together with the degradation of soil and other natural resources due to high-input industrial farming, provide further challenges in terms of agriculture and future food security. Agricultural production in South Africa faces three obstacles: water scarcity, infertile soils and poor institutional support. Therefore, regenerative and sustainable agriculture practices such as organic farming, are increasingly being promoted as an alternative to conventional farming systems in southern Africa. What is the best way of farming? This is the question every farmer is confronted with. Some say organic whilst others say conventional, but how do we determine this? What is the role of crop rotation in pest management, soil fertility and crop yield? So we set up the research to compare the two farming systems so that decisions can be based on sound scientific findings. Results showed a significant increase in the case of the organic yield in season 2016/17 for cabbage and in both seasons (2016/17 & 2017/18) for cowpea and sweet potato, proving that organic farming yields can increase over time. Soil fertility changes from the baseline year (2014) till the end of season 2017/18 were compared. Overall organic farming systems showed very promising results with higher levels of soil pH followed by a significant increase in important soil nutrients (P, K & C) compared to conventional systems. Crop rotation also had positive effects.
- Full Text:
- Date Issued: 2019
Comparison of mesozooplankton communities at three shallow seamounts in the South West Indian Ocean using size spectrum analysis
- Rasoloarijao, Zo, Huggett, Jenny
- Authors: Rasoloarijao, Zo , Huggett, Jenny
- Date: 2019
- Subjects: Seamounts
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43012 , vital:36731
- Description: Seamounts influence ocean dynamics and consequently the surrounding ecosystem. Zooplankton communities associated with seamounts may be influenced by various mechanisms related to increased retention,such as Taylor columns and/or enhanced local productivity, leading to increased predation pressure. Through this study we investigated mesozooplankton distribution and community structure in the vicinity of three shallow seamounts in the South West Indian Ocean (SWIO) during September 2016, December 2016 and April/May 2017 at La Pérouse, MadRidge and Walters Shoal respectively. The water-column was profiled at 42 stations using a CTD-F equipped with a L-ADCP and mesozooplankton was sampled with a Bongo net or a Hydrobios Midi MultiNet, both fitted with 200 µm mesh. Walters Shoal had significantly lower mesozooplankton total abundance and biovolume compared to La Perouse and MadRidge. La Perouse and MadRidge showed similar mesozooplankton community structures with steep Normalised Biovolume Size Spectrum (NBSS) slopes, indicating higher productivity and dominance of small organisms, compared to Walters Shoal where the slopes were flatter. Total and per taxon abundances and biovolumes at locations “On” and “Off” the seamount were similar, as was the size diversity for MadRidge and Walter Shoal. None of the environmental parameters tested had a significant effect on variability of the mesozooplankton community structure at the stations overall.
- Full Text:
- Date Issued: 2019
- Authors: Rasoloarijao, Zo , Huggett, Jenny
- Date: 2019
- Subjects: Seamounts
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43012 , vital:36731
- Description: Seamounts influence ocean dynamics and consequently the surrounding ecosystem. Zooplankton communities associated with seamounts may be influenced by various mechanisms related to increased retention,such as Taylor columns and/or enhanced local productivity, leading to increased predation pressure. Through this study we investigated mesozooplankton distribution and community structure in the vicinity of three shallow seamounts in the South West Indian Ocean (SWIO) during September 2016, December 2016 and April/May 2017 at La Pérouse, MadRidge and Walters Shoal respectively. The water-column was profiled at 42 stations using a CTD-F equipped with a L-ADCP and mesozooplankton was sampled with a Bongo net or a Hydrobios Midi MultiNet, both fitted with 200 µm mesh. Walters Shoal had significantly lower mesozooplankton total abundance and biovolume compared to La Perouse and MadRidge. La Perouse and MadRidge showed similar mesozooplankton community structures with steep Normalised Biovolume Size Spectrum (NBSS) slopes, indicating higher productivity and dominance of small organisms, compared to Walters Shoal where the slopes were flatter. Total and per taxon abundances and biovolumes at locations “On” and “Off” the seamount were similar, as was the size diversity for MadRidge and Walter Shoal. None of the environmental parameters tested had a significant effect on variability of the mesozooplankton community structure at the stations overall.
- Full Text:
- Date Issued: 2019
Computational fluid dynamics design and performance testing of a cyclone heat exchanger used in a gasification plant
- Authors: George, Tomy
- Date: 2019
- Subjects: Computational fluid dynamics Renewable energy sources Biomass gasification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19087 , vital:39877
- Description: Renewable energy resources are considered to be the most promising source of energy in the coming centuries owing to its potential to get replenished by the nature itself. However, there are a number of challenges that are to be addressed prior to considering a particular resource as a reliable and effective one according to the energy demand fluctuations. Energy extracted from the biomass available in the nature has a lot of potential especially in the case of producing energy from syngas produced by the controlled burning of wood. This research deals with the minimisation of energy wastage in a gasification plant where syngas is produced from wood and transferred to an internal combustion engine to further generate electrical energy. The syngas produced from the wood is to be fed through a cyclone for purification before it can be fed into the IC engine, where the dust, carbon and other impurities are separated from the syngas by making use of the centrifugal force developed inside the cyclone. This syngas is further cooled and fed into the IC engine in its purest form as specified by the requirements of the engine. It is envisaged that if it is possible to recover the heat energy otherwise wasted in the cyclone and through the cooling circuit, it can be used for preheating the wood or for other minor heating purposes, and thereby the heat wastage can be minimised. Therefore, in this research, a series of numerical investigation conducted which involved the modelling of heat exchanger around a cyclone in order to extract heat from the surface of the cyclone. Two basic design of the Heat exchanger were considered in the study, a rectangular and a conical design. With a water flow rate of 2 l/min in conical design, the heat absorbed by the water was found to be 5.555 kJ/s and in rectangular design, the heat absorbed by the water was 4.872 kJ/s. An experimental analysis conducted to validate the simulation by a rectangular Heat exchanger shows the amount of heat absorbed by the water is 4.87 kJ/s. In a study with variable water flow rate through the jacket, it is observed that heat absorbed by the water in conical heat exchanger is more than heat absorbed by the water in rectangular jacket within the flow rate of 4 l/min. and the heat absorbed by the water in rectangular heat exchanger is higher than conical heat exchanger with water flow rate above 4 l/min.
- Full Text:
- Date Issued: 2019
- Authors: George, Tomy
- Date: 2019
- Subjects: Computational fluid dynamics Renewable energy sources Biomass gasification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19087 , vital:39877
- Description: Renewable energy resources are considered to be the most promising source of energy in the coming centuries owing to its potential to get replenished by the nature itself. However, there are a number of challenges that are to be addressed prior to considering a particular resource as a reliable and effective one according to the energy demand fluctuations. Energy extracted from the biomass available in the nature has a lot of potential especially in the case of producing energy from syngas produced by the controlled burning of wood. This research deals with the minimisation of energy wastage in a gasification plant where syngas is produced from wood and transferred to an internal combustion engine to further generate electrical energy. The syngas produced from the wood is to be fed through a cyclone for purification before it can be fed into the IC engine, where the dust, carbon and other impurities are separated from the syngas by making use of the centrifugal force developed inside the cyclone. This syngas is further cooled and fed into the IC engine in its purest form as specified by the requirements of the engine. It is envisaged that if it is possible to recover the heat energy otherwise wasted in the cyclone and through the cooling circuit, it can be used for preheating the wood or for other minor heating purposes, and thereby the heat wastage can be minimised. Therefore, in this research, a series of numerical investigation conducted which involved the modelling of heat exchanger around a cyclone in order to extract heat from the surface of the cyclone. Two basic design of the Heat exchanger were considered in the study, a rectangular and a conical design. With a water flow rate of 2 l/min in conical design, the heat absorbed by the water was found to be 5.555 kJ/s and in rectangular design, the heat absorbed by the water was 4.872 kJ/s. An experimental analysis conducted to validate the simulation by a rectangular Heat exchanger shows the amount of heat absorbed by the water is 4.87 kJ/s. In a study with variable water flow rate through the jacket, it is observed that heat absorbed by the water in conical heat exchanger is more than heat absorbed by the water in rectangular jacket within the flow rate of 4 l/min. and the heat absorbed by the water in rectangular heat exchanger is higher than conical heat exchanger with water flow rate above 4 l/min.
- Full Text:
- Date Issued: 2019
Critical success factors of South African construction companies
- Authors: Lombard, Daniel
- Date: 2019
- Subjects: Construction industry -- Planning -- South Africa , Construction industry -- Management Construction industry -- South Africa Success in business -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42229 , vital:36637
- Description: The aim of the study was to identify the driving forces of the South African construction industry for registered cidb Grade 9 companies. The next objective was to identify the critical success factors (CSF) that are required to be used by the forward-looking and pro-active cidb Grade 9 companies. The most important critical success factors were then highlighted to form a core group of CSFs for construction industry. From this core group of CSFs an attempt was then made to identify business strategies that can assist companies in gaining a competitive advantage in the construction industry of South Africa. The research was based on the problem statement from which the sub-questions and hypothesis were derived. The primary data was collected through a mixed method of quantitative and qualitative research. A ontological philosophy was used for the research to effectively collaborate with the mixed method of research used. The approach of the research was a mix of both inductive and deductive, as it pursued to identify the forces and factors dominating the construction industry. The study subsequently determined what business strategies best suit these results. The research questionnaire was distributed between senior managers of grade 9 cidb construction companies and found that the most eminent driving forces of the industry are political and government decision making, as well as economic conditions. The CSFs showed a clear indication of what the respondents perceived as the most important factors. Although there have been many advances in technology and processes over the years, the most important CSF for contractors are still the processes of bidding and tendering and the factors relating to these. The qualitative research portion of the study was an investigation on what business strategies were best related to the key driving forces and most important CSFs. Interviews were held with directors of cidb grade 9 construction companies. The themes that were identified from the analyses of the qualitative data were that business strategies relevant to differentiation, diversification, cost leadership or hybrid were seen as the most effective for construction companies. The bidding and tendering process is not merely the same process that it used to be. Frequent reviews of what the industry is going through have also become a major necessity. The research was limited to companies registered as grade 9 with the Construction Industry Development Board. The research is seen as valued as the construction industry is highly important towards the development of the economy of a country and the impact that it has on communities.
- Full Text:
- Date Issued: 2019
- Authors: Lombard, Daniel
- Date: 2019
- Subjects: Construction industry -- Planning -- South Africa , Construction industry -- Management Construction industry -- South Africa Success in business -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42229 , vital:36637
- Description: The aim of the study was to identify the driving forces of the South African construction industry for registered cidb Grade 9 companies. The next objective was to identify the critical success factors (CSF) that are required to be used by the forward-looking and pro-active cidb Grade 9 companies. The most important critical success factors were then highlighted to form a core group of CSFs for construction industry. From this core group of CSFs an attempt was then made to identify business strategies that can assist companies in gaining a competitive advantage in the construction industry of South Africa. The research was based on the problem statement from which the sub-questions and hypothesis were derived. The primary data was collected through a mixed method of quantitative and qualitative research. A ontological philosophy was used for the research to effectively collaborate with the mixed method of research used. The approach of the research was a mix of both inductive and deductive, as it pursued to identify the forces and factors dominating the construction industry. The study subsequently determined what business strategies best suit these results. The research questionnaire was distributed between senior managers of grade 9 cidb construction companies and found that the most eminent driving forces of the industry are political and government decision making, as well as economic conditions. The CSFs showed a clear indication of what the respondents perceived as the most important factors. Although there have been many advances in technology and processes over the years, the most important CSF for contractors are still the processes of bidding and tendering and the factors relating to these. The qualitative research portion of the study was an investigation on what business strategies were best related to the key driving forces and most important CSFs. Interviews were held with directors of cidb grade 9 construction companies. The themes that were identified from the analyses of the qualitative data were that business strategies relevant to differentiation, diversification, cost leadership or hybrid were seen as the most effective for construction companies. The bidding and tendering process is not merely the same process that it used to be. Frequent reviews of what the industry is going through have also become a major necessity. The research was limited to companies registered as grade 9 with the Construction Industry Development Board. The research is seen as valued as the construction industry is highly important towards the development of the economy of a country and the impact that it has on communities.
- Full Text:
- Date Issued: 2019
Damage recovery for robot controllers and simulators evolved using bootstrapped neuro-simulation
- Authors: Leonard, Brydon Andrew
- Date: 2019
- Subjects: Robots -- Control systems , Robots -- Programming Robotics Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40424 , vital:36164
- Description: Robots are becoming increasingly complex. This has made manually designing the software responsible for controlling these robots (controllers) challenging, leading to the creation of the field of evolutionary robotics (ER). The ER approach aims to automatically evolve robot controllers and morphologies by utilising concepts from biological evolution. ER techniques use evolutionary algorithms (EA) to evolve populations of controllers - a process that requires the evaluation of a large number of controllers. Performing these evaluations on a real-world robot is both infeasibly time-consuming and poses the risk of damage to the robot. Simulators present a solution to the issue by allowing the evaluation of controllers to take place on a virtual robot. Traditional methods of controller evolution in simulation encounter two major issues. Firstly, physics simulators are complex to create and are often very computationally expensive. Secondly, the reality gap is encountered when controllers are evolved in simulators that are unable to simulate the real world well enough due to implications or small inaccuracies in the simulation, which together cause controllers in the simulation to be unable to transfer effectively to reality. Bootstrapped Neuro-Simulation (BNS) is an ER algorithm that aims to address the issues inherent with the use of simulators. The algorithm concurrently creates a simulator and evolves a population of controllers. The process starts with an initially random population of controllers and an untrained simulator neural network (SNN), a type of robot simulator which utilises artificial neural networks (ANNs) to simulate a robot's behaviour. Controllers are then continually selected for evaluation in the real world, and the data from these real-world evaluations is used to train the controller-evaluation SNN. BNS is a relatively new algorithm that has not yet been explored in depth. An investigation was, therefore, conducted into BNS's ability to evolve closed-loop controllers. BNS was successful in evolving such controllers, and various adaptations to the algorithm were investigated for their ability to improve the evolution of closed-loop controllers. In addition, the factors which had the greatest impact on BNS's effectiveness were reported upon. Damage recovery is an area that has been the focus of a great deal of research. This is because the progression of the field of robotics means that robots no longer operate only in the safe environments that they once did. Robots are now put to use in areas as inaccessible as the surface of Mars, where repairs by a human are impossible. Various methods of damage recovery have previously been proposed and evaluated, but none focused on BNS as a method of damage recovery. In this research, it was hypothesised that BNS's constantly learning nature would allow it to recover from damage, as it would continue to use new information about the state of the real robot to evolve new controllers capable of functioning in the damaged robot. BNS was found to possess the hypothesised damage recovery ability. The algorithm's evaluation was carried out through the evolution of controllers for simple navigation and light-following tasks for a wheeled robot, as well as a locomotion task for a complex legged robot. Various adaptations to the algorithm were then evaluated through extensive parameter investigations in simulation, showing varying levels of effectiveness. These results were further confirmed through evaluation of the adaptations and effective parameter values in real-world evaluations on a real robot. Both a simple and more complex robot morphology were investigated.
- Full Text:
- Date Issued: 2019
- Authors: Leonard, Brydon Andrew
- Date: 2019
- Subjects: Robots -- Control systems , Robots -- Programming Robotics Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40424 , vital:36164
- Description: Robots are becoming increasingly complex. This has made manually designing the software responsible for controlling these robots (controllers) challenging, leading to the creation of the field of evolutionary robotics (ER). The ER approach aims to automatically evolve robot controllers and morphologies by utilising concepts from biological evolution. ER techniques use evolutionary algorithms (EA) to evolve populations of controllers - a process that requires the evaluation of a large number of controllers. Performing these evaluations on a real-world robot is both infeasibly time-consuming and poses the risk of damage to the robot. Simulators present a solution to the issue by allowing the evaluation of controllers to take place on a virtual robot. Traditional methods of controller evolution in simulation encounter two major issues. Firstly, physics simulators are complex to create and are often very computationally expensive. Secondly, the reality gap is encountered when controllers are evolved in simulators that are unable to simulate the real world well enough due to implications or small inaccuracies in the simulation, which together cause controllers in the simulation to be unable to transfer effectively to reality. Bootstrapped Neuro-Simulation (BNS) is an ER algorithm that aims to address the issues inherent with the use of simulators. The algorithm concurrently creates a simulator and evolves a population of controllers. The process starts with an initially random population of controllers and an untrained simulator neural network (SNN), a type of robot simulator which utilises artificial neural networks (ANNs) to simulate a robot's behaviour. Controllers are then continually selected for evaluation in the real world, and the data from these real-world evaluations is used to train the controller-evaluation SNN. BNS is a relatively new algorithm that has not yet been explored in depth. An investigation was, therefore, conducted into BNS's ability to evolve closed-loop controllers. BNS was successful in evolving such controllers, and various adaptations to the algorithm were investigated for their ability to improve the evolution of closed-loop controllers. In addition, the factors which had the greatest impact on BNS's effectiveness were reported upon. Damage recovery is an area that has been the focus of a great deal of research. This is because the progression of the field of robotics means that robots no longer operate only in the safe environments that they once did. Robots are now put to use in areas as inaccessible as the surface of Mars, where repairs by a human are impossible. Various methods of damage recovery have previously been proposed and evaluated, but none focused on BNS as a method of damage recovery. In this research, it was hypothesised that BNS's constantly learning nature would allow it to recover from damage, as it would continue to use new information about the state of the real robot to evolve new controllers capable of functioning in the damaged robot. BNS was found to possess the hypothesised damage recovery ability. The algorithm's evaluation was carried out through the evolution of controllers for simple navigation and light-following tasks for a wheeled robot, as well as a locomotion task for a complex legged robot. Various adaptations to the algorithm were then evaluated through extensive parameter investigations in simulation, showing varying levels of effectiveness. These results were further confirmed through evaluation of the adaptations and effective parameter values in real-world evaluations on a real robot. Both a simple and more complex robot morphology were investigated.
- Full Text:
- Date Issued: 2019
Design and Characterization of a 5 kw Xe-Lamp Solar Simulator
- Authors: Nwodo, Julian Chizoba
- Date: 2019
- Subjects: Solar energy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14671 , vital:40042
- Description: The design and characterisation of a 5kW Xenon lamp solar simulator is presented. This was accomplished through considering the design features of an ellipsoidal reflector, Xe lamp characteristics and casing, and power supply; assembly of an ellipsoidal, Xe-lamp simulator; design and building of an automated control system capable of remotely controlling the operating mode of the simulator; establishing the 3 scenarios that must be met to conform to a AAA class simulator; characterization of the simulator in terms of temporal stability, irradiance uniformity and spectral match; and application of the simulator and comparing it with STC rated values. The considerations for the type of material used for housing the components of the solar simulator were made. A 5kW DC power supply and igniter for the Xe-lamp was carefully selected since they provide necessary power for running the simulator. The simulator has the ability to be used in either horizontal or vertical position by adjusting the reflector. An automated control system capable of remotely controlling the operating mode of the simulator was built for this study, this system enables the simulator to be operated in either auto or manual modes. It also incorporates an irradiance, temperature, current and voltage feedback. The characterisation of the solar simulator was over a 2.1 m X 1.6 m test plane. The area under which the characterisation was carried out within the test plane is 110 cm x 129.5 cm. At the end of the steady state large area solar simulator characterisation, a class A spectral match, class A spatial uniformity, and a class B temporal instability was obtained
- Full Text:
- Date Issued: 2019
- Authors: Nwodo, Julian Chizoba
- Date: 2019
- Subjects: Solar energy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14671 , vital:40042
- Description: The design and characterisation of a 5kW Xenon lamp solar simulator is presented. This was accomplished through considering the design features of an ellipsoidal reflector, Xe lamp characteristics and casing, and power supply; assembly of an ellipsoidal, Xe-lamp simulator; design and building of an automated control system capable of remotely controlling the operating mode of the simulator; establishing the 3 scenarios that must be met to conform to a AAA class simulator; characterization of the simulator in terms of temporal stability, irradiance uniformity and spectral match; and application of the simulator and comparing it with STC rated values. The considerations for the type of material used for housing the components of the solar simulator were made. A 5kW DC power supply and igniter for the Xe-lamp was carefully selected since they provide necessary power for running the simulator. The simulator has the ability to be used in either horizontal or vertical position by adjusting the reflector. An automated control system capable of remotely controlling the operating mode of the simulator was built for this study, this system enables the simulator to be operated in either auto or manual modes. It also incorporates an irradiance, temperature, current and voltage feedback. The characterisation of the solar simulator was over a 2.1 m X 1.6 m test plane. The area under which the characterisation was carried out within the test plane is 110 cm x 129.5 cm. At the end of the steady state large area solar simulator characterisation, a class A spectral match, class A spatial uniformity, and a class B temporal instability was obtained
- Full Text:
- Date Issued: 2019
Determination of social, environmental and economic benefits for community participation in forestry in Mpumalanga, South Africa
- Long, Leo Searle, Chirwa, Paxie
- Authors: Long, Leo Searle , Chirwa, Paxie
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- Mpumalanga
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34339 , vital:33307
- Description: Rural communities living adjacent to commercial forestry operations are often affected by numerous negative social issues such as poverty, unemployment, poor healthcare, and limited infrastructure, amongst others. In excess of 61% of forestry land managed by the state owned SAFCOL SOC Ltd is under land claim, as part of the Restitution of Land Rights Act (Act 22 of 1994). It is therefore necessary for forest companies to seek active means of engaging and partnering with these communities through a participatory forest management (PFM) approach. This study explored the sustainable (social, environmental and economic), benefits of such an approach as perceived (experienced) by these local rural communities, and specifically land claimants. The study was conducted in communities adjacent to SAFCOL plantations in the Mpumalanga Province of South Africa. Data were collected between May and June 2017 by means of a structured questionnaire. Surveys were conducted on 46 households within the identified communities so as to verify and evaluate perceived benefits in terms of forest products, ecosystem services and amenities/services/infrastructure provided by SAFCOL and the broader forest industry. The results indicated that these communities recognize and obtain numerous social, environmental and economic benefits from the forest including Non-Timber Forest Products (NTFPs) such as firewood; forest provisioning ecosystem services (FPESs) such as improved water quality; and more metaphysical benefits such as access to gravesites and the protection of traditions and customs. These benefits have the ability to improve the social well-being, economic independence, and the quality of environmental services obtained by the associated communities. It was however found that the utilization of these benefits was widely differentiated according to gender and land claimant status. Whilst males and females largely benefitted equally, there was a distinct benefit preference between genders for different NTFPs. For example males showed preference for the collection of building material, bush meat and for livestock husbandry, whilst females showed preference for the collection of firewood, medicinal plants and fruit, amongst others. Similarly, it was found that overall, non-land claimants benefited more than land claimants. Reasons for this are primarily due to the increased distance with which the land claimants live from the forest resource when compared to non-land claimants. The empirical value of the data produced through this study will be invaluable in negotiations with the land claimant communities on land settlement agreements, joint venture proposals, including Participatory Forest Management, and future land tenure. Through such inclusivity and vested interest in the sustainable management of the forests, corporate risk is reduced and community/land claimant relationships are reinforced. Such Participatory Forest Management arrangements are key to ensuring the longevity and resilience to the forest sector post-transfer of claimed land.
- Full Text:
- Date Issued: 2019
- Authors: Long, Leo Searle , Chirwa, Paxie
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- Mpumalanga
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34339 , vital:33307
- Description: Rural communities living adjacent to commercial forestry operations are often affected by numerous negative social issues such as poverty, unemployment, poor healthcare, and limited infrastructure, amongst others. In excess of 61% of forestry land managed by the state owned SAFCOL SOC Ltd is under land claim, as part of the Restitution of Land Rights Act (Act 22 of 1994). It is therefore necessary for forest companies to seek active means of engaging and partnering with these communities through a participatory forest management (PFM) approach. This study explored the sustainable (social, environmental and economic), benefits of such an approach as perceived (experienced) by these local rural communities, and specifically land claimants. The study was conducted in communities adjacent to SAFCOL plantations in the Mpumalanga Province of South Africa. Data were collected between May and June 2017 by means of a structured questionnaire. Surveys were conducted on 46 households within the identified communities so as to verify and evaluate perceived benefits in terms of forest products, ecosystem services and amenities/services/infrastructure provided by SAFCOL and the broader forest industry. The results indicated that these communities recognize and obtain numerous social, environmental and economic benefits from the forest including Non-Timber Forest Products (NTFPs) such as firewood; forest provisioning ecosystem services (FPESs) such as improved water quality; and more metaphysical benefits such as access to gravesites and the protection of traditions and customs. These benefits have the ability to improve the social well-being, economic independence, and the quality of environmental services obtained by the associated communities. It was however found that the utilization of these benefits was widely differentiated according to gender and land claimant status. Whilst males and females largely benefitted equally, there was a distinct benefit preference between genders for different NTFPs. For example males showed preference for the collection of building material, bush meat and for livestock husbandry, whilst females showed preference for the collection of firewood, medicinal plants and fruit, amongst others. Similarly, it was found that overall, non-land claimants benefited more than land claimants. Reasons for this are primarily due to the increased distance with which the land claimants live from the forest resource when compared to non-land claimants. The empirical value of the data produced through this study will be invaluable in negotiations with the land claimant communities on land settlement agreements, joint venture proposals, including Participatory Forest Management, and future land tenure. Through such inclusivity and vested interest in the sustainable management of the forests, corporate risk is reduced and community/land claimant relationships are reinforced. Such Participatory Forest Management arrangements are key to ensuring the longevity and resilience to the forest sector post-transfer of claimed land.
- Full Text:
- Date Issued: 2019
Determining the hydrological functioning of the palmiet wetlands in the Eastern and Western Cape South Africa
- Authors: Smith, Caitlin
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Wetland ecology -- South Africa -- Eastern Cape , Wetland management -- South Africa -- Eastern Cape , Prioniaceae -- South Africa -- Eastern Cape , Prionium serratum -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95956 , vital:31218
- Description: Wetlands provide a range of supporting, regulating and provisioning ecosystem services, including hydrological benefits such as flood attenuation and sustaining base flows. Despite their value, wetlands are one of the most vulnerable ecosystems in South Africa. Palmiet wetlands in the Eastern and Western Cape are particularly threatened. Palmiet (Prionium serratum) is a robust perennial plant that is endemic to wetlands and rivers located in the sandstones and quartzites of the Table Mountain Group (TMG), in the Eastern and Western Cape as well as the Natal Group sandstones in KwaZulu-Natal. Palmiet is described as an ecosystem engineer because of its ability to alter its environment and create large valley-bottom wetlands. The Krom River is an important water source for the city of Port Elizabeth and there has been a decline in palmiet wetlands along the Krom River as a result of alien vegetation invasion, agricultural activity, and gully erosion. Working for Water has been clearing alien vegetation and Working for Wetlands has been installing rehabilitation structures in the Krom River catchment for a number of years. There are, however, serious knowledge gaps in the understanding of palmiet wetland structure and function, particularly in respect of the hydrological functioning of these wetland systems. The aim of this study was to investigate the hydrology (surface and groundwater) behind these wetland systems. The investigation focussed on small-scale dynamics of the palmiet wetland system in order to increase general understanding of the surface water and groundwater processes of these wetland systems. Field work was concentrated on the Kompanjiesdrif and Krugersland palmiet wetlands in the upper K90A Krom River catchment. The investigation involved the installation of piezometers, water quality and stable isotope sampling and analysis, an Electrical Resistivity Tomography survey, and hydrological and mixing cell modelling. The results of the investigation indicate that the hydrological functioning of palmiet wetlands is closely linked with high sub-surface discharges typically associated with TMG aquifers. It is proposed that the palmiet wetlands are sustained by significant amounts of sub-surface water (both groundwater and interflow) moving through preferential flow paths in the alluvial fans and tributaries, which are in turn sustained by groundwater discharge from the surrounding sandstones and quartzites of the Nardouw Sub-group and Peninsula Formation. The palmiet wetlands clearly retain a significant amount of water, leading to the maintenance of prolonged flows, and a larger baseflow. However, it is hypothesised that the occurrence of palmiet as the dominant species in these wetlands is due to the sustained low flows related to catchment geology and high hydrological connectivity between the catchment and the wetland that is enabled by flow paths that allow the free flow of water from the catchment to the wetland. It is further proposed that palmiet is possibly more reliant on a consistent water supply for its existence and survival than it is on acidic nutrient-poor water and soils as stated by other authors.
- Full Text:
- Date Issued: 2019
- Authors: Smith, Caitlin
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Wetland ecology -- South Africa -- Eastern Cape , Wetland management -- South Africa -- Eastern Cape , Prioniaceae -- South Africa -- Eastern Cape , Prionium serratum -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95956 , vital:31218
- Description: Wetlands provide a range of supporting, regulating and provisioning ecosystem services, including hydrological benefits such as flood attenuation and sustaining base flows. Despite their value, wetlands are one of the most vulnerable ecosystems in South Africa. Palmiet wetlands in the Eastern and Western Cape are particularly threatened. Palmiet (Prionium serratum) is a robust perennial plant that is endemic to wetlands and rivers located in the sandstones and quartzites of the Table Mountain Group (TMG), in the Eastern and Western Cape as well as the Natal Group sandstones in KwaZulu-Natal. Palmiet is described as an ecosystem engineer because of its ability to alter its environment and create large valley-bottom wetlands. The Krom River is an important water source for the city of Port Elizabeth and there has been a decline in palmiet wetlands along the Krom River as a result of alien vegetation invasion, agricultural activity, and gully erosion. Working for Water has been clearing alien vegetation and Working for Wetlands has been installing rehabilitation structures in the Krom River catchment for a number of years. There are, however, serious knowledge gaps in the understanding of palmiet wetland structure and function, particularly in respect of the hydrological functioning of these wetland systems. The aim of this study was to investigate the hydrology (surface and groundwater) behind these wetland systems. The investigation focussed on small-scale dynamics of the palmiet wetland system in order to increase general understanding of the surface water and groundwater processes of these wetland systems. Field work was concentrated on the Kompanjiesdrif and Krugersland palmiet wetlands in the upper K90A Krom River catchment. The investigation involved the installation of piezometers, water quality and stable isotope sampling and analysis, an Electrical Resistivity Tomography survey, and hydrological and mixing cell modelling. The results of the investigation indicate that the hydrological functioning of palmiet wetlands is closely linked with high sub-surface discharges typically associated with TMG aquifers. It is proposed that the palmiet wetlands are sustained by significant amounts of sub-surface water (both groundwater and interflow) moving through preferential flow paths in the alluvial fans and tributaries, which are in turn sustained by groundwater discharge from the surrounding sandstones and quartzites of the Nardouw Sub-group and Peninsula Formation. The palmiet wetlands clearly retain a significant amount of water, leading to the maintenance of prolonged flows, and a larger baseflow. However, it is hypothesised that the occurrence of palmiet as the dominant species in these wetlands is due to the sustained low flows related to catchment geology and high hydrological connectivity between the catchment and the wetland that is enabled by flow paths that allow the free flow of water from the catchment to the wetland. It is further proposed that palmiet is possibly more reliant on a consistent water supply for its existence and survival than it is on acidic nutrient-poor water and soils as stated by other authors.
- 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
Development and characterisation of miconazole nitrate loaded solid lipid nanoparticles for incorporation into a vaginal mucoadhesive system
- Authors: Gwimo, Wimana Alexis
- Date: 2019
- Subjects: Vaginitis , Vagina -- Diseases Sexually transmitted diseases -- Diagnosis Sexually transmitted diseases -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39632 , vital:35335
- Description: Vulvovaginal candidiasis (VVC) is the second most common cause of vaginitis, affecting 75% of women of sexual maturity. The prescribed first line treatment involves the use of locally-acting imidazole creams. These conventional dosage forms possess limitations, such as leakage, messiness and low residence time at the site of application; all which promote poor patient adherence to pharmacotherapy. Poor adherence is then attributed to increased incidence of VVC reoccurrence and the emergence of Candida strains. It was, therefore, speculated that through the use of novel drug delivery systems (NDDS), the pharmacokinetic and antimicrobial characteristics of a model antifungal drug (miconazole nitrate [MNZ]) could be improved. Primary aim: To develop, optimise and characterise a mucoadhesive hydrogel incorporated with MNZ loaded solid lipid nanoparticles (MNZ-SLNs) for the intended treatment of VVC. This study was conducted in three phases, viz. pre-formulation studies, development, optimisation and characterisation of MNZ-SLNs, and the development and characterisation of MNZ-SLN-loaded thermoresponsive hydrogel. An alternative method for the quantification of MNZ was developed through the use of an octyl stationary phase. The method was deemed suitable for its intended use with a linear equation of y = 811214x + 67958 and a respective limit of quantitation (LoQ) and detection of 0.015 mg/ml and 0.052 mg/ml. Differential scanning calorimetry (DSC) studies suggested that cholesterol showed great promise of facilitating high drug entrapment efficiency (EE). MNZ-SLNs were prepared by means of a novel melt- emulsification sonication and low temperature solidification method and optimised statistically by a 13-run-two-factor central composite rotatable design (CCRD). The predicted optimisation parameters were 4% m/v lipid concentration and 260.94 sonication time. Optimal MNZ-SLN formulations were prepared and characterised by means of photon correlation spectroscopy (PCS), transmission electron microscopy (TEM) and centrifugation. PCS revealed uniform particles with a narrow polydispersity index (PDI) and a mean hydrodynamic diameter (z-avg.) of 73.03 nm and zeta potential (ZP) of 38.43 mV. Percent EE was calculated via an indirect method as 75.24%. Furthermore, the MNZ -SLNs were incorporated into a mucoadhesive thermo-responsive hydrogel with a sol-gel transition temperature of 33.33 ± 2.82 °C. In vitro drug release testing (IVDRT) was undertaken with the aid of a Franz diffusion vertical cell (FDVC) apparatus. A % cumulative drug release of 27.94% and 15.87% was obtained for MNZ- SLNs and MNZ-SLN hydrogels, respectively, after eight hours. The resultant data was fitted into various kinetic models with the aid of DDSolverTM (Microsoft Excel® add-ins, 2016) to evaluate which model attained the highest correlation co-efficient (r2). Both formulations attained high r2 of 0.9941 and 0.9945, respectively, with the Korsmeyer- Peppas mathematical model. A high diffusional exponent (n) of >1 was observed, suggesting a super case II drug release mechanism. Finally, a modified Kirby-Bauer disc diffusion assay was used for ascertaining Candida albicans susceptibility to the developed formulations. Controls in the form of unloaded preparations and a commercially available cream were used. MNZ-SLNs and MNZ-hydrogel demonstrated superior antifungal activity to the commercially available cream. These results indicate that the developed MNZ-SLNloaded hydrogel formulation with localised thermo-responsive effect may be a promising carrier for intravaginal delivery of MNZ in the treatment of VVC.
- Full Text:
- Date Issued: 2019
- Authors: Gwimo, Wimana Alexis
- Date: 2019
- Subjects: Vaginitis , Vagina -- Diseases Sexually transmitted diseases -- Diagnosis Sexually transmitted diseases -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39632 , vital:35335
- Description: Vulvovaginal candidiasis (VVC) is the second most common cause of vaginitis, affecting 75% of women of sexual maturity. The prescribed first line treatment involves the use of locally-acting imidazole creams. These conventional dosage forms possess limitations, such as leakage, messiness and low residence time at the site of application; all which promote poor patient adherence to pharmacotherapy. Poor adherence is then attributed to increased incidence of VVC reoccurrence and the emergence of Candida strains. It was, therefore, speculated that through the use of novel drug delivery systems (NDDS), the pharmacokinetic and antimicrobial characteristics of a model antifungal drug (miconazole nitrate [MNZ]) could be improved. Primary aim: To develop, optimise and characterise a mucoadhesive hydrogel incorporated with MNZ loaded solid lipid nanoparticles (MNZ-SLNs) for the intended treatment of VVC. This study was conducted in three phases, viz. pre-formulation studies, development, optimisation and characterisation of MNZ-SLNs, and the development and characterisation of MNZ-SLN-loaded thermoresponsive hydrogel. An alternative method for the quantification of MNZ was developed through the use of an octyl stationary phase. The method was deemed suitable for its intended use with a linear equation of y = 811214x + 67958 and a respective limit of quantitation (LoQ) and detection of 0.015 mg/ml and 0.052 mg/ml. Differential scanning calorimetry (DSC) studies suggested that cholesterol showed great promise of facilitating high drug entrapment efficiency (EE). MNZ-SLNs were prepared by means of a novel melt- emulsification sonication and low temperature solidification method and optimised statistically by a 13-run-two-factor central composite rotatable design (CCRD). The predicted optimisation parameters were 4% m/v lipid concentration and 260.94 sonication time. Optimal MNZ-SLN formulations were prepared and characterised by means of photon correlation spectroscopy (PCS), transmission electron microscopy (TEM) and centrifugation. PCS revealed uniform particles with a narrow polydispersity index (PDI) and a mean hydrodynamic diameter (z-avg.) of 73.03 nm and zeta potential (ZP) of 38.43 mV. Percent EE was calculated via an indirect method as 75.24%. Furthermore, the MNZ -SLNs were incorporated into a mucoadhesive thermo-responsive hydrogel with a sol-gel transition temperature of 33.33 ± 2.82 °C. In vitro drug release testing (IVDRT) was undertaken with the aid of a Franz diffusion vertical cell (FDVC) apparatus. A % cumulative drug release of 27.94% and 15.87% was obtained for MNZ- SLNs and MNZ-SLN hydrogels, respectively, after eight hours. The resultant data was fitted into various kinetic models with the aid of DDSolverTM (Microsoft Excel® add-ins, 2016) to evaluate which model attained the highest correlation co-efficient (r2). Both formulations attained high r2 of 0.9941 and 0.9945, respectively, with the Korsmeyer- Peppas mathematical model. A high diffusional exponent (n) of >1 was observed, suggesting a super case II drug release mechanism. Finally, a modified Kirby-Bauer disc diffusion assay was used for ascertaining Candida albicans susceptibility to the developed formulations. Controls in the form of unloaded preparations and a commercially available cream were used. MNZ-SLNs and MNZ-hydrogel demonstrated superior antifungal activity to the commercially available cream. These results indicate that the developed MNZ-SLNloaded hydrogel formulation with localised thermo-responsive effect may be a promising carrier for intravaginal delivery of MNZ in the treatment of VVC.
- Full Text:
- Date Issued: 2019
Development of a manual to train food handlers of the national school nutrition programme
- Authors: Barkhuizen, Kirsten Lyn
- Date: 2019
- Subjects: Food -- Safety measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/36559 , vital:33974
- Description: The study was conducted in order to develop a hygiene and food safety manual that can be used to train the food handlers of the National School Nutrition Programme. The co-operation of the Institute for International Medicine, Partnerships with Children, as part of the Health in Action Programme in this study, is appreciated. Food handlers of the National School Nutrition Programme in low socio-economic schools, in the Nelson Mandela Bay, in the Eastern Cape, were the population of the study. With many South Africans experiencing poverty and food insecurity, the National School Nutrition Programme aims to provide a social safety net and address short term hunger in children. However, challenges are faced regarding the implementation thereof, such as a lack of training of food handlers. This results in poor hygiene and food safety knowledge and behaviour. Subsequently, the risk of transmission of foodborne pathogens and the contamination of food rises. Foodborne illnesses are a major cause of morbidity and mortality, specifically in children, due to weak immune systems. Therefore, the study was conducted in order to develop and test a hygiene and food safety manual so that it can be made available to the South African Department of Education to be used by teachers in order to train the food handlers of the National School Nutrition Programme. The manual can then be used to train all newly recruited food handlers, and therefore ensure that school meals are safe to consume by learners.
- Full Text:
- Date Issued: 2019
- Authors: Barkhuizen, Kirsten Lyn
- Date: 2019
- Subjects: Food -- Safety measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/36559 , vital:33974
- Description: The study was conducted in order to develop a hygiene and food safety manual that can be used to train the food handlers of the National School Nutrition Programme. The co-operation of the Institute for International Medicine, Partnerships with Children, as part of the Health in Action Programme in this study, is appreciated. Food handlers of the National School Nutrition Programme in low socio-economic schools, in the Nelson Mandela Bay, in the Eastern Cape, were the population of the study. With many South Africans experiencing poverty and food insecurity, the National School Nutrition Programme aims to provide a social safety net and address short term hunger in children. However, challenges are faced regarding the implementation thereof, such as a lack of training of food handlers. This results in poor hygiene and food safety knowledge and behaviour. Subsequently, the risk of transmission of foodborne pathogens and the contamination of food rises. Foodborne illnesses are a major cause of morbidity and mortality, specifically in children, due to weak immune systems. Therefore, the study was conducted in order to develop and test a hygiene and food safety manual so that it can be made available to the South African Department of Education to be used by teachers in order to train the food handlers of the National School Nutrition Programme. The manual can then be used to train all newly recruited food handlers, and therefore ensure that school meals are safe to consume by learners.
- Full Text:
- Date Issued: 2019
Development of a nystatin-loaded micellar system for oral mucoadhesion
- Authors: Sarpong, Nancy Owusu Akyere
- Date: 2019
- Subjects: Medical microbiology , HIV infections -- Treatment Clinical pharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43556 , vital:36918
- Description: Oropharyngeal Candidiasis (OPC) is an opportunistic fungal infection that affects mostly infants and immunocompromised patients. In recent years, the disease has been on the rise due to an increased life span, the HIV pandemic and the increased use of broad spectrum antibiotics. OPC may be treated using a nystatin suspension, which is not as effective as it could be due to the mechanism by which the suspension is applied to the affected tissue. This research aims to improve the effectiveness of nystatin, for the treatment of OPC, by proposing a nystatin loaded micellar system incorporated into a mucoadhesive system for drug delivery. This will ensure that nystatin is gradually released from the film, thus increasing retention time of nystatin at the affected area. In this study, a mixture design was developed, which was used to determine the most appropriate solvent system for nystatin solubilization. Optimisation of the micelle formulation was achieved by using the central composite rational design (CCRD). The two factors that were taken into consideration were the temperature of the hydration medium (water) and the length of time the micellar solution was exposed to the temperature environment of the rotary evaporator. The responses that were investigated were the mean particle size, mean polydispersity index (PDI), mean zeta potential, change in mean particle size and change in mean PDI. The optimal micelle formulation was characterised for size, stability, morphology and drug encapsulation efficiency. The micelles were found to be spherical and stable with an acceptable size range. However, their drug encapsulation efficiency was low. The mucoadhesive film was formulated and characterised for physical characteristics, pliability, percentage swelling index and drug release profile. The film was found to be highly pliable and evenly distributed with a smooth surface; no bumps or bubbles were visible. The film was able to swell to up to 550 %. In vitro studies showed that nystatin was gradually released from the film.
- Full Text:
- Date Issued: 2019
- Authors: Sarpong, Nancy Owusu Akyere
- Date: 2019
- Subjects: Medical microbiology , HIV infections -- Treatment Clinical pharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43556 , vital:36918
- Description: Oropharyngeal Candidiasis (OPC) is an opportunistic fungal infection that affects mostly infants and immunocompromised patients. In recent years, the disease has been on the rise due to an increased life span, the HIV pandemic and the increased use of broad spectrum antibiotics. OPC may be treated using a nystatin suspension, which is not as effective as it could be due to the mechanism by which the suspension is applied to the affected tissue. This research aims to improve the effectiveness of nystatin, for the treatment of OPC, by proposing a nystatin loaded micellar system incorporated into a mucoadhesive system for drug delivery. This will ensure that nystatin is gradually released from the film, thus increasing retention time of nystatin at the affected area. In this study, a mixture design was developed, which was used to determine the most appropriate solvent system for nystatin solubilization. Optimisation of the micelle formulation was achieved by using the central composite rational design (CCRD). The two factors that were taken into consideration were the temperature of the hydration medium (water) and the length of time the micellar solution was exposed to the temperature environment of the rotary evaporator. The responses that were investigated were the mean particle size, mean polydispersity index (PDI), mean zeta potential, change in mean particle size and change in mean PDI. The optimal micelle formulation was characterised for size, stability, morphology and drug encapsulation efficiency. The micelles were found to be spherical and stable with an acceptable size range. However, their drug encapsulation efficiency was low. The mucoadhesive film was formulated and characterised for physical characteristics, pliability, percentage swelling index and drug release profile. The film was found to be highly pliable and evenly distributed with a smooth surface; no bumps or bubbles were visible. The film was able to swell to up to 550 %. In vitro studies showed that nystatin was gradually released from the film.
- 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
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
Effect of dietary Mucuna pruriens seed meal on the serum lipid profile and bone quality traits of broiler chickens
- Authors: Hempe, Chumani
- Date: 2019
- Subjects: Legumes Lipoproteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17213 , vital:40866
- Description: This study aimed at evaluating the effects of heated Mucuna pruriens seed meal on the blood serum lipid profile and bone quality parameters of broiler chickens. A total of 120 day-old unsexed Cobb 500 broiler chicks were randomly allocated for the 4 treatment diets (T1, T2, T3 and T4) containing 0, 10, 15, and 20% heated Mucuna pruriens seed meal. The birds were reared on wood shaving floor pens for 35 days. Birds were humanely slaughtered by severing the jugular vein using a sharp knife. Blood was collected into a tube, centrifuge and analyzed for a lipid profile analysis (total cholesterol (TC), high density lipoproteins (HDL), low density lipoproteins (LDL), triglycerides (TCD) as well as aspartate transaminase (AST) and alanine transaminase (ALT)) by enzymatic diagnostic kits (Diasys diagnostic kits). Both drumsticks severed using a sharp knife. After boiling in the water at 100°C for 10 mins the tibia bones were taken, air-dried for 96 hrs at room temperature and measured for weights. Bone length, strength, moisture and ash content as well as morphology were measured. The blood lipid profile of birds fed T1 was high (P < 0.05) for all the parameters measured, while T3 had the lowest (P < 0.05) profile. T2 and T4 had the same profile. ALT was found to be highest (P < 0.05) for T4 (5.27 ± 0.207/L) and lowest (P < 0.05) for T2 (4.67 ± 0.333/L) while AST was highest (P < 0.05) for T2 (320.13 ± 28.851/L) and lowest (P < 0.05) for T3 (208.47 ± 10.059/L). Treatment diet 3 (T3) was observed decreased bone quality among all diets; with the lowest (P < 0.05) bone strength (188.55 ± 12.039N), bone length (8.59 ± 0.131cm) and morphology (1.69 ± 0.058). Mucuna pruriens seed meal inclusion in broiler diets reduces blood serum lipids and 20% inclusion levels have no adverse effects on the bone quality attributes
- Full Text:
- Date Issued: 2019
- Authors: Hempe, Chumani
- Date: 2019
- Subjects: Legumes Lipoproteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17213 , vital:40866
- Description: This study aimed at evaluating the effects of heated Mucuna pruriens seed meal on the blood serum lipid profile and bone quality parameters of broiler chickens. A total of 120 day-old unsexed Cobb 500 broiler chicks were randomly allocated for the 4 treatment diets (T1, T2, T3 and T4) containing 0, 10, 15, and 20% heated Mucuna pruriens seed meal. The birds were reared on wood shaving floor pens for 35 days. Birds were humanely slaughtered by severing the jugular vein using a sharp knife. Blood was collected into a tube, centrifuge and analyzed for a lipid profile analysis (total cholesterol (TC), high density lipoproteins (HDL), low density lipoproteins (LDL), triglycerides (TCD) as well as aspartate transaminase (AST) and alanine transaminase (ALT)) by enzymatic diagnostic kits (Diasys diagnostic kits). Both drumsticks severed using a sharp knife. After boiling in the water at 100°C for 10 mins the tibia bones were taken, air-dried for 96 hrs at room temperature and measured for weights. Bone length, strength, moisture and ash content as well as morphology were measured. The blood lipid profile of birds fed T1 was high (P < 0.05) for all the parameters measured, while T3 had the lowest (P < 0.05) profile. T2 and T4 had the same profile. ALT was found to be highest (P < 0.05) for T4 (5.27 ± 0.207/L) and lowest (P < 0.05) for T2 (4.67 ± 0.333/L) while AST was highest (P < 0.05) for T2 (320.13 ± 28.851/L) and lowest (P < 0.05) for T3 (208.47 ± 10.059/L). Treatment diet 3 (T3) was observed decreased bone quality among all diets; with the lowest (P < 0.05) bone strength (188.55 ± 12.039N), bone length (8.59 ± 0.131cm) and morphology (1.69 ± 0.058). Mucuna pruriens seed meal inclusion in broiler diets reduces blood serum lipids and 20% inclusion levels have no adverse effects on the bone quality attributes
- Full Text:
- Date Issued: 2019