Waste management in the informal settlements of Msukaligwa Municipality
- Authors: Ngema, , Noxolo Nondumiso
- Date: 2020
- Subjects: Waste disposal in the ground -- South Africa -- Ermelo , Refuse and refuse disposal -- South Africa -- Ermelo Squatters -- South Africa -- Ermelo
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/46827 , vital:39665
- Description: This study focused on waste management, and, sought to evaluate the level of awareness on environmental impact of littering in vulnerable communities in the informal settlements of Msukaligwa municipality, in particular at Ward 16 which is Nyibe newly named as New Ermelo. This study was, thus, concerned with how solid waste is managed within the informal settlements. The study arose with the concern that the environment is mostly affected when informal settlements are developed. If informal settlements are less aware of the damage caused by littering and improper waste disposal, the waste management plan of a local municipality becomes ineffective where local communities do not assume their responsibilities for ensuring healthy and safe living environments. A quantitative research design was applied in this study. Population for this research comprised of Msukaligwa Local Municipality, with a study sample drawn from Ward 16 Nyibe households, church leaders, local business owners, and ward councillor. A nonprobability sampling technique for selection of study participants was used, and this technique applied in both households and stakeholders. Data was collected through self-administered survey questionnaires that were statistically analysed, weaving in filed observations, where deemed necessary. The researcher discovered that Nyibe (New Ermelo) community’s level of awareness of the environmental impact of littering is impressively above average. Majority of households’ respondents identified all the negative environmental impact caused by littering in vulnerable communities and the impact is considered a major challenge within Nyibe. Necessary waste disposal infrastructures are not provided at Nyibe leading to people littering on any open land, burning, or throwing solid waste in their family pit.
- Full Text:
- Date Issued: 2020
- Authors: Ngema, , Noxolo Nondumiso
- Date: 2020
- Subjects: Waste disposal in the ground -- South Africa -- Ermelo , Refuse and refuse disposal -- South Africa -- Ermelo Squatters -- South Africa -- Ermelo
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/46827 , vital:39665
- Description: This study focused on waste management, and, sought to evaluate the level of awareness on environmental impact of littering in vulnerable communities in the informal settlements of Msukaligwa municipality, in particular at Ward 16 which is Nyibe newly named as New Ermelo. This study was, thus, concerned with how solid waste is managed within the informal settlements. The study arose with the concern that the environment is mostly affected when informal settlements are developed. If informal settlements are less aware of the damage caused by littering and improper waste disposal, the waste management plan of a local municipality becomes ineffective where local communities do not assume their responsibilities for ensuring healthy and safe living environments. A quantitative research design was applied in this study. Population for this research comprised of Msukaligwa Local Municipality, with a study sample drawn from Ward 16 Nyibe households, church leaders, local business owners, and ward councillor. A nonprobability sampling technique for selection of study participants was used, and this technique applied in both households and stakeholders. Data was collected through self-administered survey questionnaires that were statistically analysed, weaving in filed observations, where deemed necessary. The researcher discovered that Nyibe (New Ermelo) community’s level of awareness of the environmental impact of littering is impressively above average. Majority of households’ respondents identified all the negative environmental impact caused by littering in vulnerable communities and the impact is considered a major challenge within Nyibe. Necessary waste disposal infrastructures are not provided at Nyibe leading to people littering on any open land, burning, or throwing solid waste in their family pit.
- Full Text:
- Date Issued: 2020
The influence of the integration of local knowledge during chemistry hands-on practical activities on grade 8/9 learners’ attitude towards science
- Authors: Ngqinambi, Akhona
- Date: 2020
- Subjects: Science -- Study and teaching (Secondary) -- South Africa , Science teachers -- South Africa , High school students -- Attitudes , Communities of practice -- South Africa , Science clubs -- South Africa , Science projects -- South Africa , Constructivism (Education) -- South Africa , Educational counseling -- South Africa , Local knowledge
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/144724 , vital:38373
- Description: With every passing year, there is a decrease in the number of learners pursuing science degrees after completion of grade 12. One of the main reasons for this is the negative attitude that high school learners have towards science learning and science as an entity. The Natural Sciences curriculum suggests the use of local knowledge to introduce the usefulness and the relatability of science to learners. This study is an intervention that seeks to ascertain the influence that local knowledge has on the attitudes of grade 8/9 learners when integrated into their chemistry hands-on practical activities. The study was informed by Vygotsky’s social constructivist theory and Wenger’s community of practice theory. Grade 8/9 learners from four high school science clubs did three local knowledge integrated experiments based on acids and bases. The learners completed pre- and post- surveys and were interviewed about their experiences. Volunteers at the science clubs were also interviewed. Excel was used to deductively analyse quantitative data. On the other hand, an inductive-deductive thematic approach was used to analyse the qualitative data. The findings of the study showed a divergence of qualitative and quantitative methods. The quantitative data showed that there was a slight decrease (but not statistically significant) in the attitude of the learners after engaging in chemistry hands-on practical activities into which local knowledge had been integrated. On the other hand, the qualitative data showed that there was a positive shift in the learners’ attitudes after they had been engaged in the chemistry hands-on practical activities. Additionally, the findings of the study revealed that the integration of local knowledge promotes conceptual understanding and improves the performance of the learners. This study thus recommends that local knowledge should be integrated into the grade 8 and 9 learners’ curriculum to enrich and promote contextualized science for learners. Additionally, the integration of local knowledge would promote conceptual understanding and spark interest and motivation in learners to pursue science-related careers.
- Full Text:
- Date Issued: 2020
- Authors: Ngqinambi, Akhona
- Date: 2020
- Subjects: Science -- Study and teaching (Secondary) -- South Africa , Science teachers -- South Africa , High school students -- Attitudes , Communities of practice -- South Africa , Science clubs -- South Africa , Science projects -- South Africa , Constructivism (Education) -- South Africa , Educational counseling -- South Africa , Local knowledge
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/144724 , vital:38373
- Description: With every passing year, there is a decrease in the number of learners pursuing science degrees after completion of grade 12. One of the main reasons for this is the negative attitude that high school learners have towards science learning and science as an entity. The Natural Sciences curriculum suggests the use of local knowledge to introduce the usefulness and the relatability of science to learners. This study is an intervention that seeks to ascertain the influence that local knowledge has on the attitudes of grade 8/9 learners when integrated into their chemistry hands-on practical activities. The study was informed by Vygotsky’s social constructivist theory and Wenger’s community of practice theory. Grade 8/9 learners from four high school science clubs did three local knowledge integrated experiments based on acids and bases. The learners completed pre- and post- surveys and were interviewed about their experiences. Volunteers at the science clubs were also interviewed. Excel was used to deductively analyse quantitative data. On the other hand, an inductive-deductive thematic approach was used to analyse the qualitative data. The findings of the study showed a divergence of qualitative and quantitative methods. The quantitative data showed that there was a slight decrease (but not statistically significant) in the attitude of the learners after engaging in chemistry hands-on practical activities into which local knowledge had been integrated. On the other hand, the qualitative data showed that there was a positive shift in the learners’ attitudes after they had been engaged in the chemistry hands-on practical activities. Additionally, the findings of the study revealed that the integration of local knowledge promotes conceptual understanding and improves the performance of the learners. This study thus recommends that local knowledge should be integrated into the grade 8 and 9 learners’ curriculum to enrich and promote contextualized science for learners. Additionally, the integration of local knowledge would promote conceptual understanding and spark interest and motivation in learners to pursue science-related careers.
- Full Text:
- Date Issued: 2020
The effect of muscle type and freezing on the evolution of physico-chemical properties during processing of South African biltong and its final textural properties
- Authors: Ngwendu, Nwabisa
- Date: 2020
- Subjects: Biltong Meat -- Quality -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12128 , vital:39154
- Description: The study investigated the effect of muscle type and freezing on evaluation of mass transfer during processing physico-chemical of South African biltong and its textural properties. In the first experimental phase of this study, mass transfers, physico-chemical and textural properties (hardness, cohesiveness, springiness, and chewiness) of commercially produced biltong from biceps femoris (BF) and semitendinosus (ST) (n=9) were measured. Biltong was dried at 30oC and 40% relative humidity until it had lost 50% of its initial weight. The initial moisture content, water activity (Aw) of BF muscles (74.3% and 0.992) were significantly lower compared those of ST muscles (75.4% and 0.994%). The fat content of BF (2.3%) muscles was higher (P<0.05) than in ST muscles (1.7%). The salt, weight and water gain for the BF muscle were 2.3%, -2.6% and -7.0% respectively and were significantly higher than those of ST muscles which were 2.1, -0.4 and -4.0, respectively. After drying, the moisture content, Aw, and pH were lower in BF (42.2, 0.886 and 5.29) than those of ST muscles (45.1, 0.911 and 5.42). The salt content was higher (P<0.05) in BF muscle than in ST. Among textural properties, hardness was significantly higher in biltong from the BF (233.0N), while the springiness was significantly lower compared to the ST muscle (178.2N). Therefore, it was concluded that the use of different muscles results in variation of biltong physicochemical characteristics. The second experiment investigated the effect of freezing and muscle type on mass transfers, lipid oxidation, physico-chemical and textural properties of biltong. In this experiment, the iii ST muscles were replaced with semimembranosus (SM) muscles. A total of 12 beef muscles were used, with six BF and six SM muscles frozen in a blast freezer at -40 oC till they reached -20oC; then they were transferred to -20oC for 14 days. The thawing loss for the BF and ST muscles was 1.3 and 2.4% respectively, but there were no significant (P>0.05) differences. The protein and salt content were significantly higher in frozen-thawed (24.3 and 0.13%) muscles than in fresh muscle (20.2 and 0.08%); whereas the fat content and pH were lower (P<0.05) in frozen-thawed (5.36) compared to fresh muscles (5.51). Between muscles, the moisture, salt content, and pH were higher in BF muscles than in SM muscles (73.2, 0.12% and 5.49). Aw was affected by the interaction between freezing and muscle type, with frozenthawed SM having lower Aw (0.990). During salting, salt, weight and water gain did not show any differences (P<0.05). There were no major significant differences after salting. There were lower TBARS and pH in frozen-thawed (1.5mgMDA/kg and 5.15) muscles than in fresh muscles (3.3mgMDA/kg and 5.19) as well as in SM muscles (1.8mgMDA/kg and 5.16) than in BF muscles (3.0mgMDA/kg and 5.19). The moisture was significantly lower in frozen-thawed SM (68.1%) than in fresh SM, BF and frozen-thawed BF (69.3,70.5 and 71.7%) after salting. On the final product, the interaction between muscle type and freezing affected the moisture content, TBARS, chewiness and the springiness of biltong, with the biltong from fresh SM (39.8%) having significantly lower moisture content compared frozenthawed BF and ST muscles as well fresh BF muscles (42.8% in average). The TBARS were higher in biltong from fresh BF muscles (5.1mgMDA/kg) compared to other muscles. Furthermore, the chewiness and springiness were higher (P<0.05) in biltong produced from SM frozen-thawed muscles (327.7N and 1.5). The WBSF was higher in biltong from the BF muscles (108.8N) than in the biltong from SM (80.1) but it was not affected by the freezing effect (P>0.05). Freezing did not show any major differences in biltong. iv The third experiment was conducted to determine the effect of freezing African buffalo carcasses on weight loss during salting, physico-chemical and textural properties of biltong. Five muscles (ST, SM, BF, LTL, and RF) were randomly selected from 30 carcasses (15 frozen-thawed and 15 fresh), cut along the grain, traditionally salted and dried at 26oC till they lost 45-50% of their initial weight. The salting weight loss was higher in frozen-thawed muscles (-1.45%) than in fresh muscles (-0.89%). The freezing treatment affected the physico-chemical properties of the biltong. The biltong produced from frozen-thawed muscles showed significantly higher protein and ash (47.6 and 7.6%) compared to fresh (43.9 and 7.1); whereas the moisture, fat, pH and Aw were lower (43.7, 2.1, 0.870 and 5.30, respectively) compared to those of biltong from fresh muscles (45.5%, 2.9%, 0.890 and 5.38). The moisture, pH and fat content were further affected by muscle type. The interactive effect was observed in salt content, with RF frozen-thawed showing higher salt content (8.2%) compared to all other muscles. The hardness and WBSF were significantly higher (P<0.05) in biltong frozen-thawed (204.1N and 135.0N) than in fresh muscles (146.2N and 113.1N). Moreover, the chewiness and springiness were affected (P<0.05) by muscle type, with RF muscle having higher springiness 0.89 and chewiness 171.1N than all the other muscles. Therefore, it can be concluded that freezing buffalo carcasses significantly influenced the quality characteristics of biltong. The fourth experiment studied the effect of drying methods on physico-chemical properties of traditional biltong produced from African buffalo muscles. The BF and SM muscles were randomly selected from 15 fresh carcasses, cut into strips, salted and divided into two batches per muscle. The first batch of each muscle type was dried in the ambient-air drier at 22oC average and the second batch in the cabinet drier at 26 oC till 45-50% weight loss. No differences (P>0.05) were observed in salting weight loss between the drying method and muscle type. The protein content was significantly higher in SM (46%) muscles compared to v BF (43%) but there was no effect (P>0.05) caused by the drying method. The interactions between the muscle type and drying method affected the fat content, with biltong from airdried BF muscles having significant lower (2.1%) fat content. There were no significant differences in other physico-chemical properties of biltong, with moisture content, salt, ash content, Aw and pH being 45.0%, 5.13%, 44.8%, 7.3%, 2.7%, 0.885 and 5.61 on average, respectively. Overall, the findings of the study show that freezing does have a significant effect on the final quality of biltong. However, it can be concluded that a significant effect on the physico-chemical properties of biltong depends on the changes of mass transfers during salting and drying.
- Full Text:
- Date Issued: 2020
- Authors: Ngwendu, Nwabisa
- Date: 2020
- Subjects: Biltong Meat -- Quality -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12128 , vital:39154
- Description: The study investigated the effect of muscle type and freezing on evaluation of mass transfer during processing physico-chemical of South African biltong and its textural properties. In the first experimental phase of this study, mass transfers, physico-chemical and textural properties (hardness, cohesiveness, springiness, and chewiness) of commercially produced biltong from biceps femoris (BF) and semitendinosus (ST) (n=9) were measured. Biltong was dried at 30oC and 40% relative humidity until it had lost 50% of its initial weight. The initial moisture content, water activity (Aw) of BF muscles (74.3% and 0.992) were significantly lower compared those of ST muscles (75.4% and 0.994%). The fat content of BF (2.3%) muscles was higher (P<0.05) than in ST muscles (1.7%). The salt, weight and water gain for the BF muscle were 2.3%, -2.6% and -7.0% respectively and were significantly higher than those of ST muscles which were 2.1, -0.4 and -4.0, respectively. After drying, the moisture content, Aw, and pH were lower in BF (42.2, 0.886 and 5.29) than those of ST muscles (45.1, 0.911 and 5.42). The salt content was higher (P<0.05) in BF muscle than in ST. Among textural properties, hardness was significantly higher in biltong from the BF (233.0N), while the springiness was significantly lower compared to the ST muscle (178.2N). Therefore, it was concluded that the use of different muscles results in variation of biltong physicochemical characteristics. The second experiment investigated the effect of freezing and muscle type on mass transfers, lipid oxidation, physico-chemical and textural properties of biltong. In this experiment, the iii ST muscles were replaced with semimembranosus (SM) muscles. A total of 12 beef muscles were used, with six BF and six SM muscles frozen in a blast freezer at -40 oC till they reached -20oC; then they were transferred to -20oC for 14 days. The thawing loss for the BF and ST muscles was 1.3 and 2.4% respectively, but there were no significant (P>0.05) differences. The protein and salt content were significantly higher in frozen-thawed (24.3 and 0.13%) muscles than in fresh muscle (20.2 and 0.08%); whereas the fat content and pH were lower (P<0.05) in frozen-thawed (5.36) compared to fresh muscles (5.51). Between muscles, the moisture, salt content, and pH were higher in BF muscles than in SM muscles (73.2, 0.12% and 5.49). Aw was affected by the interaction between freezing and muscle type, with frozenthawed SM having lower Aw (0.990). During salting, salt, weight and water gain did not show any differences (P<0.05). There were no major significant differences after salting. There were lower TBARS and pH in frozen-thawed (1.5mgMDA/kg and 5.15) muscles than in fresh muscles (3.3mgMDA/kg and 5.19) as well as in SM muscles (1.8mgMDA/kg and 5.16) than in BF muscles (3.0mgMDA/kg and 5.19). The moisture was significantly lower in frozen-thawed SM (68.1%) than in fresh SM, BF and frozen-thawed BF (69.3,70.5 and 71.7%) after salting. On the final product, the interaction between muscle type and freezing affected the moisture content, TBARS, chewiness and the springiness of biltong, with the biltong from fresh SM (39.8%) having significantly lower moisture content compared frozenthawed BF and ST muscles as well fresh BF muscles (42.8% in average). The TBARS were higher in biltong from fresh BF muscles (5.1mgMDA/kg) compared to other muscles. Furthermore, the chewiness and springiness were higher (P<0.05) in biltong produced from SM frozen-thawed muscles (327.7N and 1.5). The WBSF was higher in biltong from the BF muscles (108.8N) than in the biltong from SM (80.1) but it was not affected by the freezing effect (P>0.05). Freezing did not show any major differences in biltong. iv The third experiment was conducted to determine the effect of freezing African buffalo carcasses on weight loss during salting, physico-chemical and textural properties of biltong. Five muscles (ST, SM, BF, LTL, and RF) were randomly selected from 30 carcasses (15 frozen-thawed and 15 fresh), cut along the grain, traditionally salted and dried at 26oC till they lost 45-50% of their initial weight. The salting weight loss was higher in frozen-thawed muscles (-1.45%) than in fresh muscles (-0.89%). The freezing treatment affected the physico-chemical properties of the biltong. The biltong produced from frozen-thawed muscles showed significantly higher protein and ash (47.6 and 7.6%) compared to fresh (43.9 and 7.1); whereas the moisture, fat, pH and Aw were lower (43.7, 2.1, 0.870 and 5.30, respectively) compared to those of biltong from fresh muscles (45.5%, 2.9%, 0.890 and 5.38). The moisture, pH and fat content were further affected by muscle type. The interactive effect was observed in salt content, with RF frozen-thawed showing higher salt content (8.2%) compared to all other muscles. The hardness and WBSF were significantly higher (P<0.05) in biltong frozen-thawed (204.1N and 135.0N) than in fresh muscles (146.2N and 113.1N). Moreover, the chewiness and springiness were affected (P<0.05) by muscle type, with RF muscle having higher springiness 0.89 and chewiness 171.1N than all the other muscles. Therefore, it can be concluded that freezing buffalo carcasses significantly influenced the quality characteristics of biltong. The fourth experiment studied the effect of drying methods on physico-chemical properties of traditional biltong produced from African buffalo muscles. The BF and SM muscles were randomly selected from 15 fresh carcasses, cut into strips, salted and divided into two batches per muscle. The first batch of each muscle type was dried in the ambient-air drier at 22oC average and the second batch in the cabinet drier at 26 oC till 45-50% weight loss. No differences (P>0.05) were observed in salting weight loss between the drying method and muscle type. The protein content was significantly higher in SM (46%) muscles compared to v BF (43%) but there was no effect (P>0.05) caused by the drying method. The interactions between the muscle type and drying method affected the fat content, with biltong from airdried BF muscles having significant lower (2.1%) fat content. There were no significant differences in other physico-chemical properties of biltong, with moisture content, salt, ash content, Aw and pH being 45.0%, 5.13%, 44.8%, 7.3%, 2.7%, 0.885 and 5.61 on average, respectively. Overall, the findings of the study show that freezing does have a significant effect on the final quality of biltong. However, it can be concluded that a significant effect on the physico-chemical properties of biltong depends on the changes of mass transfers during salting and drying.
- Full Text:
- Date Issued: 2020
Towards the synthesis of trimethoprim using continuous flow Chemistry
- Authors: Ngwenya, Sandiso
- Date: 2020
- Subjects: Trimethoprim
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/47475 , vital:39994
- Description: The continuous flow synthesis of trimethoprim, an antibiotic, was investigated in this study from simple commercially available reagents, such as aniline and dimethylamine. The first step of the synthesis involves a highly exothermic Michael reaction, between acrylonitrile and dimethylamine; process intensification through miniaturization provides a safe and efficient method of synthesis through the use of microreactors. This is afforded by their large surface area-to-volume ratio; one of the many characteristics of continuous flow synthesis that allows for rapid heat dissipation allowing for exothermic reaction to be conducted safely at ambient or higher temperatures. This study was optimized on a Chemtrix Labtrix® Start unit using a Chemtrix reactor achieving a conversion of 99% in 12 sec residence time at 25oC. Subsequently the base catalyzed condensation of the intermediate with 3,4,5- trimethoxybenzaldehyde was investigated using Little Things Factory reactors (Channel diameter: 1.0mm). Maximum conversion (100%) was obtained at 80oC in 20 mins. Due to the poor cyclisation observed with this intermediate, according to literature findings, the 3-dimethylamino group was substituted for aniline. The optimisation for this acid catalysed substitution reaction was performed on a homemade PTFE tubing reactor (Diameter: 0.5mm) and it was found that at 120oC in 10 mins residence time a conversion of 97% was obtained. From the results obtained, an investigation into an integrated process for the condensation and substitution reaction was done using the Little Things Factory system (Channel Diameter: 1.0mm) coupled with a homemade PTFE coil reactor (Diameter: 0.5mm). This process, under optimum conditions of temperature 80oC and residence time of 30 mins, attained a conversion of 76%.
- Full Text:
- Date Issued: 2020
- Authors: Ngwenya, Sandiso
- Date: 2020
- Subjects: Trimethoprim
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/47475 , vital:39994
- Description: The continuous flow synthesis of trimethoprim, an antibiotic, was investigated in this study from simple commercially available reagents, such as aniline and dimethylamine. The first step of the synthesis involves a highly exothermic Michael reaction, between acrylonitrile and dimethylamine; process intensification through miniaturization provides a safe and efficient method of synthesis through the use of microreactors. This is afforded by their large surface area-to-volume ratio; one of the many characteristics of continuous flow synthesis that allows for rapid heat dissipation allowing for exothermic reaction to be conducted safely at ambient or higher temperatures. This study was optimized on a Chemtrix Labtrix® Start unit using a Chemtrix reactor achieving a conversion of 99% in 12 sec residence time at 25oC. Subsequently the base catalyzed condensation of the intermediate with 3,4,5- trimethoxybenzaldehyde was investigated using Little Things Factory reactors (Channel diameter: 1.0mm). Maximum conversion (100%) was obtained at 80oC in 20 mins. Due to the poor cyclisation observed with this intermediate, according to literature findings, the 3-dimethylamino group was substituted for aniline. The optimisation for this acid catalysed substitution reaction was performed on a homemade PTFE tubing reactor (Diameter: 0.5mm) and it was found that at 120oC in 10 mins residence time a conversion of 97% was obtained. From the results obtained, an investigation into an integrated process for the condensation and substitution reaction was done using the Little Things Factory system (Channel Diameter: 1.0mm) coupled with a homemade PTFE coil reactor (Diameter: 0.5mm). This process, under optimum conditions of temperature 80oC and residence time of 30 mins, attained a conversion of 76%.
- Full Text:
- Date Issued: 2020
The effect of integration of affordable/ low cost housing into urban areas on property values
- Authors: Ngxwashula, Ntomboxolo
- Date: 2020
- Subjects: Housing -- South Africa , Urban poor -- Housing -- South Africa Real property -- Valuation -- South Africa Property
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/46838 , vital:39666
- Description: In the recent years in South Africa after the apartheid era, the government has for the past 25 years been embarking on programmes and policy directives to address the past spatial injustices amongst other things that the apartheid government has left the country with. It is clear that some of the apartheid marks are still to this day evident and challenging to resolve. One of the priority government’s projects is to integrate communities without classifying areas with skin colour, income range etc. Since 1994 the government has developed a lot of legislation and policies in favour of spatial integration of low cost housing and affordable housing within the existing urban fabric. According to COGTA. (2016:22) urban areas in South Africa remain marked by profound social divisions, which stem from apartheid planning and, since 1994, have been reinforced by the uneven growth in land values and limited access by the poor to resources. The growth of the black middle class has resulted in more racial mixing in the (previously predominantly white and middle-class) suburbs, however, very little in working-class and poor areas. Furthermore it is argued that the property and land use status quo undermines access to urban opportunity and reinforces the highly inefficient urban sprawl that is characteristic of South Africa’s urban areas. There has been no substantial land reform and restitution, especially in urban areas, in part because of the importance of the formal property market, which increased significantly between 1994 and 2014. While this growth is essential to the health of rates income for municipalities, it has not addressed the issue of well-located, affordable housing and decent shelter for all. Spatial Integration has been implemented in some parts of the country, however it is evident that there is some resistance towards the concept of spatial integration and the most referred to reason for the resistance is that the integration of low cost or social housing into high income areas will decrease the property values of the existing properties in urban areas. This research aims to study and investigate if property values are affected by the inclusion of low cost housing in existing urban areas and further investigate why there is still resistance to the concept of integration and address any underpinning reasons and provide recommendations. In this study the related literature was reviewed and an empirical study was conducted. The empirical study was conducted using a combination of qualitative and quantitative approaches, referred to as Mixed Method. The research involved the use of questionnaires (Multiple Choice questions and Likert Scale format type of questions), semi-structured interviews and observation done by the researcher. The findings suggest that the following variables influence the resistance towards spatial integration of affordable/low cost housing into urban areas: Increased crime rate, Negative impact on property values, Clutch of different cultures, NIMBY Syndrome (Not in my Backyard), and Aesthetics of low cost/ social housing. The findings of this research may be used for a further research for a doctoral research investigating, more comprehensive detail, each of the identified variables in the perceived resistance towards spatial integration into urban areas framework which is apparent in the review of the related literature. In accordance with the results of this study and the testing of the objectives and sub questions, all variables have a positive influence on the perceived effect of spatial integration onto urban areas. Equally, some of the variables are not perceived to have a direct but an indirect relationship with spatial integration. The results of this research confirms this research questions and reveals two important things that, the concept of spatial integration into existing suburbia does have a negative effect on existing middle to high income properties in proximity to the social houses. Secondly the results reveal that concept of spatial integration of social housing into existing suburbia areas does positively affect the property values of the social housing. According to the definition of Property value which refers to the worth of a piece of real estate based on the price that a buyer and seller agree upon, furthermore the value of a property converges at the point where the forces of supply meet the forces of demand. In other words, the value of a property at any given time is determined by what the market will bear. Through this study it has been discovered that although property valuations for residential properties are conducted by means of a Comparative Method, which basically compares similar properties, it is however evident through this research that demand for properties located in areas where spatial integration has been implemented is very low, which leads to property owners desperately reducing their prices just to sell. Therefore this research concludes that spatial integration does have an impact on property values, though it is not a determining factor in the calculation of property value, it has an indirect impact. This study contributed to the South African property development body of knowledge, by determining the factors influencing the continued resistance towards Spatial Integration of affordable/low income housing into existing urban areas on property values.
- Full Text:
- Date Issued: 2020
- Authors: Ngxwashula, Ntomboxolo
- Date: 2020
- Subjects: Housing -- South Africa , Urban poor -- Housing -- South Africa Real property -- Valuation -- South Africa Property
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/46838 , vital:39666
- Description: In the recent years in South Africa after the apartheid era, the government has for the past 25 years been embarking on programmes and policy directives to address the past spatial injustices amongst other things that the apartheid government has left the country with. It is clear that some of the apartheid marks are still to this day evident and challenging to resolve. One of the priority government’s projects is to integrate communities without classifying areas with skin colour, income range etc. Since 1994 the government has developed a lot of legislation and policies in favour of spatial integration of low cost housing and affordable housing within the existing urban fabric. According to COGTA. (2016:22) urban areas in South Africa remain marked by profound social divisions, which stem from apartheid planning and, since 1994, have been reinforced by the uneven growth in land values and limited access by the poor to resources. The growth of the black middle class has resulted in more racial mixing in the (previously predominantly white and middle-class) suburbs, however, very little in working-class and poor areas. Furthermore it is argued that the property and land use status quo undermines access to urban opportunity and reinforces the highly inefficient urban sprawl that is characteristic of South Africa’s urban areas. There has been no substantial land reform and restitution, especially in urban areas, in part because of the importance of the formal property market, which increased significantly between 1994 and 2014. While this growth is essential to the health of rates income for municipalities, it has not addressed the issue of well-located, affordable housing and decent shelter for all. Spatial Integration has been implemented in some parts of the country, however it is evident that there is some resistance towards the concept of spatial integration and the most referred to reason for the resistance is that the integration of low cost or social housing into high income areas will decrease the property values of the existing properties in urban areas. This research aims to study and investigate if property values are affected by the inclusion of low cost housing in existing urban areas and further investigate why there is still resistance to the concept of integration and address any underpinning reasons and provide recommendations. In this study the related literature was reviewed and an empirical study was conducted. The empirical study was conducted using a combination of qualitative and quantitative approaches, referred to as Mixed Method. The research involved the use of questionnaires (Multiple Choice questions and Likert Scale format type of questions), semi-structured interviews and observation done by the researcher. The findings suggest that the following variables influence the resistance towards spatial integration of affordable/low cost housing into urban areas: Increased crime rate, Negative impact on property values, Clutch of different cultures, NIMBY Syndrome (Not in my Backyard), and Aesthetics of low cost/ social housing. The findings of this research may be used for a further research for a doctoral research investigating, more comprehensive detail, each of the identified variables in the perceived resistance towards spatial integration into urban areas framework which is apparent in the review of the related literature. In accordance with the results of this study and the testing of the objectives and sub questions, all variables have a positive influence on the perceived effect of spatial integration onto urban areas. Equally, some of the variables are not perceived to have a direct but an indirect relationship with spatial integration. The results of this research confirms this research questions and reveals two important things that, the concept of spatial integration into existing suburbia does have a negative effect on existing middle to high income properties in proximity to the social houses. Secondly the results reveal that concept of spatial integration of social housing into existing suburbia areas does positively affect the property values of the social housing. According to the definition of Property value which refers to the worth of a piece of real estate based on the price that a buyer and seller agree upon, furthermore the value of a property converges at the point where the forces of supply meet the forces of demand. In other words, the value of a property at any given time is determined by what the market will bear. Through this study it has been discovered that although property valuations for residential properties are conducted by means of a Comparative Method, which basically compares similar properties, it is however evident through this research that demand for properties located in areas where spatial integration has been implemented is very low, which leads to property owners desperately reducing their prices just to sell. Therefore this research concludes that spatial integration does have an impact on property values, though it is not a determining factor in the calculation of property value, it has an indirect impact. This study contributed to the South African property development body of knowledge, by determining the factors influencing the continued resistance towards Spatial Integration of affordable/low income housing into existing urban areas on property values.
- Full Text:
- Date Issued: 2020
Efficacy of the rind physiological disorder oleocellosis control measures in lemon fruit (Citrus limon) under shade netting
- Authors: Njili, Zamazima
- Date: 2020
- Subjects: Citrus fruits--Storage--Diseases and injuries , Citrus--Diseases and pests Citrus fruit industry Citrus products
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49237 , vital:41613
- Description: Lemon growers aim to produce fruit with no blemishes on the rind. Fruit without blemishes is regarded as high value fruit required for the export market. Leakage of phytotoxic oil from the rind tissues damages them and results in the development of oleocellosis symptoms. Four experiments were conducted to investigate methods of avoiding and controlling the development of oleocellosis during harvest and post-harvest handling. The first experiment indicated that the rind oil release pressure (RORP) test is the method most effective at predicting oleocellosis incidents. The experiment also suggested that fruit not exposed to the sun are the most susceptible to oleocellosis due to low temperatures that cause high turgidity. Oleocellosis results when turgid fruit is mishandled. A cultivar experiment was carried out to ascertain the lemon cultivar most susceptible to oleocellosis. The results show that the Limoneira cultivar is the most susceptible to oleocellosis and 2PH seedless is the least susceptible cultivar when compared to other lemon cultivars such as Lisbon, Eureka and Genoa. When the use of shade netting was tested to determine its effect on oleocellosis severity, it was found that using shade netting did not have an effect. Fruit grown under shade netting had the same colour and average diameter as fruit grown in an open orchard. In the same experiment, mature fruit were shown to be more susceptible to oleocellosis than immature fruit. The final part of the project investigated harvesting and post-harvest practices to determine those that cause oleocellosis the most. It was found that fruit after degreening had greater oleocellosis due to exposure to moisture conditions and rough handling. Another practice that results in oleocellosis occurs before waxing when the fruit was roughly transferred from the bins into the packline. The third oleocellosis inducing practice was moving fruit along the conveyor belt while it is turgid. Improvement of handling procedures to reduce oleocellosis can increase export volume and result in higher value of fruit per carton.
- Full Text:
- Date Issued: 2020
- Authors: Njili, Zamazima
- Date: 2020
- Subjects: Citrus fruits--Storage--Diseases and injuries , Citrus--Diseases and pests Citrus fruit industry Citrus products
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/49237 , vital:41613
- Description: Lemon growers aim to produce fruit with no blemishes on the rind. Fruit without blemishes is regarded as high value fruit required for the export market. Leakage of phytotoxic oil from the rind tissues damages them and results in the development of oleocellosis symptoms. Four experiments were conducted to investigate methods of avoiding and controlling the development of oleocellosis during harvest and post-harvest handling. The first experiment indicated that the rind oil release pressure (RORP) test is the method most effective at predicting oleocellosis incidents. The experiment also suggested that fruit not exposed to the sun are the most susceptible to oleocellosis due to low temperatures that cause high turgidity. Oleocellosis results when turgid fruit is mishandled. A cultivar experiment was carried out to ascertain the lemon cultivar most susceptible to oleocellosis. The results show that the Limoneira cultivar is the most susceptible to oleocellosis and 2PH seedless is the least susceptible cultivar when compared to other lemon cultivars such as Lisbon, Eureka and Genoa. When the use of shade netting was tested to determine its effect on oleocellosis severity, it was found that using shade netting did not have an effect. Fruit grown under shade netting had the same colour and average diameter as fruit grown in an open orchard. In the same experiment, mature fruit were shown to be more susceptible to oleocellosis than immature fruit. The final part of the project investigated harvesting and post-harvest practices to determine those that cause oleocellosis the most. It was found that fruit after degreening had greater oleocellosis due to exposure to moisture conditions and rough handling. Another practice that results in oleocellosis occurs before waxing when the fruit was roughly transferred from the bins into the packline. The third oleocellosis inducing practice was moving fruit along the conveyor belt while it is turgid. Improvement of handling procedures to reduce oleocellosis can increase export volume and result in higher value of fruit per carton.
- Full Text:
- Date Issued: 2020
Symmetry and asymmetry in electrocatalysis: enhancing the electrocatalytic activity of phthalocyanines through synergy with doped graphene quantum dots
- Nkhahle, Reitumetse Precious
- Authors: Nkhahle, Reitumetse Precious
- Date: 2020
- Subjects: Phthalocyanines , Quantum dots , Graphene
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117585 , vital:34529
- Description: An exploration on the enhancement of the electrocatalytic activity of phthalocyanines (Pcs) through coupling with a series of graphene quantum dots (GQDs) is undertaken. The preliminary studies using symmetrical Pcs, a cobalt and an iron chloride tetra substituted diethylaminophenoxy Pc (complexes 1 and 2), for the electro-oxidation of nitrite revealed through the various sequential modifications that doped GQDs fare better than their pristine counterparts with respect to improving the electrocatalytic behaviour of Pcs, in particular, the nitrogen-doped GQDs (NGQDs). Following up on this, a series of asymmetric Pc complexes; 2,9,16-tris-(4-tert-butylphenoxy) mono carboxyphenoxy phthalocyanato cobalt (II) (3), 2,9,16-tris-(4-tert-butylphenoxy) mono aminophenoxy phthalocyanato cobalt (II) (4), 2,9,16-tris-(3-diethylamino)phenoxy) mono carboxyphenoxy phthalocyanato cobalt (II) (5) and 2,9,16-tris-(3-diethylamino)phenoxy) mono aminophenoxy phthalocyanato cobalt (II) (6) was prepared in which push-pull systems were compared to other asymmetric complexes that lack this effect towards the electrocatalytic sensing of hydrazine. All asymmetric complexes (3-6) were π-stacked to the NGQDs while those with an NH2 group (4 and 6), were also covalently linked to the NGQDs. These complexes and their corresponding conjugates were characterized accordingly and applied as electrocatalysts in the oxidation of hydrazine. The electrochemical studies revealed that π π stacking yields better responses (higher sensitivities and lower limits of detection) than covalent linking because there are less forces acting on the graphene network. Covalent linking introduces both tensile and compressive forces which in turn results in an increase in the ID/IG ratio and that is unfavourable for electrocatalysis. In comparing the electrodes composed of the π-stacked conjugates to those altered through sequential modifications, despite the conditions not being the same, it can be inferred that the magnitude of the electrostatic forces between the Pcs and the GQDs also plays a significant role in electrocatalysis. The π-stacked conjugates, owing to the manner in which they were prepared, have stronger electrostatic forces acting between the Pc and GQDs hence they were able to elicit a better electrochemical response than the sequentially modified electrodes. In addition to that, it appears that asymmetric Pcs are better electrocatalysts in comparison to the symmetric Pcs.
- Full Text:
- Date Issued: 2020
- Authors: Nkhahle, Reitumetse Precious
- Date: 2020
- Subjects: Phthalocyanines , Quantum dots , Graphene
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117585 , vital:34529
- Description: An exploration on the enhancement of the electrocatalytic activity of phthalocyanines (Pcs) through coupling with a series of graphene quantum dots (GQDs) is undertaken. The preliminary studies using symmetrical Pcs, a cobalt and an iron chloride tetra substituted diethylaminophenoxy Pc (complexes 1 and 2), for the electro-oxidation of nitrite revealed through the various sequential modifications that doped GQDs fare better than their pristine counterparts with respect to improving the electrocatalytic behaviour of Pcs, in particular, the nitrogen-doped GQDs (NGQDs). Following up on this, a series of asymmetric Pc complexes; 2,9,16-tris-(4-tert-butylphenoxy) mono carboxyphenoxy phthalocyanato cobalt (II) (3), 2,9,16-tris-(4-tert-butylphenoxy) mono aminophenoxy phthalocyanato cobalt (II) (4), 2,9,16-tris-(3-diethylamino)phenoxy) mono carboxyphenoxy phthalocyanato cobalt (II) (5) and 2,9,16-tris-(3-diethylamino)phenoxy) mono aminophenoxy phthalocyanato cobalt (II) (6) was prepared in which push-pull systems were compared to other asymmetric complexes that lack this effect towards the electrocatalytic sensing of hydrazine. All asymmetric complexes (3-6) were π-stacked to the NGQDs while those with an NH2 group (4 and 6), were also covalently linked to the NGQDs. These complexes and their corresponding conjugates were characterized accordingly and applied as electrocatalysts in the oxidation of hydrazine. The electrochemical studies revealed that π π stacking yields better responses (higher sensitivities and lower limits of detection) than covalent linking because there are less forces acting on the graphene network. Covalent linking introduces both tensile and compressive forces which in turn results in an increase in the ID/IG ratio and that is unfavourable for electrocatalysis. In comparing the electrodes composed of the π-stacked conjugates to those altered through sequential modifications, despite the conditions not being the same, it can be inferred that the magnitude of the electrostatic forces between the Pcs and the GQDs also plays a significant role in electrocatalysis. The π-stacked conjugates, owing to the manner in which they were prepared, have stronger electrostatic forces acting between the Pc and GQDs hence they were able to elicit a better electrochemical response than the sequentially modified electrodes. In addition to that, it appears that asymmetric Pcs are better electrocatalysts in comparison to the symmetric Pcs.
- Full Text:
- Date Issued: 2020
Petrographic and geochemical characterisation of the hangingwall and the footwall rocks (the Dipeta and R.A.T. stratigraphic units) to the Kinsevere and Nambulwa copper ore deposits of the Lufilian Arc, southern Democratic Republic of Congo
- Authors: Nkulu, Robert Kankomba
- Date: 2020
- Subjects: Petrogenesis -- Congo (Democratic Republic) , Analytical geochemistry -- Congo (Democratic Republic) , Copper ores -- Congo (Democratic Republic) , Ore deposits -- Congo (Democratic Republic) , Katangan Sequence , Geological mapping -- Congo (Democratic Republic) , Central African Copperbelt (Congo and Zambia) , Lufilian Arc , Neoproterozoic Katangan R.A.T. (Roches Argilo Talqueuse) Subgroup , Dipeta Subgroup
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/142772 , vital:38115
- Description: The Kinsevere and Nambulwa copper deposits in the Democratic Republic of Congo (D.R.C.) are set in the eastern side of the Neoproterozoic Katanga Supergroup, forming the Lufilian Arc, resulting from a cratonic collision between the Congo and the Kalahari Cratons (ca.620-570_Ma). The Katanga Supergroup was deposited in an extensional rift setting with a sedimentary thickness succession ranging between 7 to 10 km, sub-divided into: − the Roan, the Nguba and the Kundelungu Groups. The stratigraphic column of the Roan Group consists of the R.A.T. (Roche Argilo Talqueuse), the Mines, the Dipeta and the Mwashya Subgroups. Three major deformation phases have been described characterised by complex multiphase tectonics related to a curved superposition of folded, thrust and sheared blocks. The rocks of the R.A.T., Mines and Dipeta Subgroups are recognised as blocks that occur within a stratiform to discordant and diapiritic megabreccia. The blocks were rafted upward with salt tectonics, resulting in the juxtaposition with the hangingwall and the footwall terranes. Therefore, in that context it has been found that the Dipeta may appear overlying the R.A.T. Subgroup through the unconformity decollement surface of heterogeneous breccia. The petrographic observations made of the R.A.T. and Dipeta samples indicates in both units the presence of detrital quartz and feldspar that have been altered and replaced by sericite and muscovite minerals. Gypsum is intimately associated with magnesite, showing an evaporitic environment domain, while magnesite is common as alteration phase both in the R.A.T. and Dipeta Subgroups. Pyrophyllite has been observed in the Dipeta, resulting from reaction of silica with the Kaolinite at low temperature. Accessory detrital minerals include zircon, as well as xenotime intergrown with altered Fe-Ti-oxide hematite, forming complex textures with disseminated Ti-oxides both in R.A.T. and Dipeta units. Major and trace element geochemistry indicates that the Dipeta is more dolomitic and magnesite while the R.A.T. is clay-rich. The Ti2O value of Dipeta and R.A.T samples is relatively low, ranging between 0.36 and 0.69 wt.% respectively, which suggest highly evolved felsic material in the protolith. This is consistent with interpretation based on the Al2O3/TiO2 ratio, which ranges between 18 and 23 for the R.A.T. and Dipeta respectively, indicating an intermediate to felsic granitoids as the protolith of R.A.T. and Dipeta siltstones. The Ti/Zr ratio of R.A.T. and Dipeta samples of less than 10, while, the higher La/Sc ratio of between 2.6 and 5.5 (for the R.A.T. and Dipeta respectively) indicate that both the R.A.T. and Dipeta are active continental and passive margin tectonic setting. Based on the geochemical variation with depth across the R.A.T. and Dipeta and their contact zone, a geochemical fingerprinting suggests that the ratio TiO2/Al2O3 appears to be useful and could be considered as a stratigraphic geochemical maker able to discriminate the R.A.T. and the Dipeta Subgroups during the geological mapping.
- Full Text:
- Date Issued: 2020
- Authors: Nkulu, Robert Kankomba
- Date: 2020
- Subjects: Petrogenesis -- Congo (Democratic Republic) , Analytical geochemistry -- Congo (Democratic Republic) , Copper ores -- Congo (Democratic Republic) , Ore deposits -- Congo (Democratic Republic) , Katangan Sequence , Geological mapping -- Congo (Democratic Republic) , Central African Copperbelt (Congo and Zambia) , Lufilian Arc , Neoproterozoic Katangan R.A.T. (Roches Argilo Talqueuse) Subgroup , Dipeta Subgroup
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/142772 , vital:38115
- Description: The Kinsevere and Nambulwa copper deposits in the Democratic Republic of Congo (D.R.C.) are set in the eastern side of the Neoproterozoic Katanga Supergroup, forming the Lufilian Arc, resulting from a cratonic collision between the Congo and the Kalahari Cratons (ca.620-570_Ma). The Katanga Supergroup was deposited in an extensional rift setting with a sedimentary thickness succession ranging between 7 to 10 km, sub-divided into: − the Roan, the Nguba and the Kundelungu Groups. The stratigraphic column of the Roan Group consists of the R.A.T. (Roche Argilo Talqueuse), the Mines, the Dipeta and the Mwashya Subgroups. Three major deformation phases have been described characterised by complex multiphase tectonics related to a curved superposition of folded, thrust and sheared blocks. The rocks of the R.A.T., Mines and Dipeta Subgroups are recognised as blocks that occur within a stratiform to discordant and diapiritic megabreccia. The blocks were rafted upward with salt tectonics, resulting in the juxtaposition with the hangingwall and the footwall terranes. Therefore, in that context it has been found that the Dipeta may appear overlying the R.A.T. Subgroup through the unconformity decollement surface of heterogeneous breccia. The petrographic observations made of the R.A.T. and Dipeta samples indicates in both units the presence of detrital quartz and feldspar that have been altered and replaced by sericite and muscovite minerals. Gypsum is intimately associated with magnesite, showing an evaporitic environment domain, while magnesite is common as alteration phase both in the R.A.T. and Dipeta Subgroups. Pyrophyllite has been observed in the Dipeta, resulting from reaction of silica with the Kaolinite at low temperature. Accessory detrital minerals include zircon, as well as xenotime intergrown with altered Fe-Ti-oxide hematite, forming complex textures with disseminated Ti-oxides both in R.A.T. and Dipeta units. Major and trace element geochemistry indicates that the Dipeta is more dolomitic and magnesite while the R.A.T. is clay-rich. The Ti2O value of Dipeta and R.A.T samples is relatively low, ranging between 0.36 and 0.69 wt.% respectively, which suggest highly evolved felsic material in the protolith. This is consistent with interpretation based on the Al2O3/TiO2 ratio, which ranges between 18 and 23 for the R.A.T. and Dipeta respectively, indicating an intermediate to felsic granitoids as the protolith of R.A.T. and Dipeta siltstones. The Ti/Zr ratio of R.A.T. and Dipeta samples of less than 10, while, the higher La/Sc ratio of between 2.6 and 5.5 (for the R.A.T. and Dipeta respectively) indicate that both the R.A.T. and Dipeta are active continental and passive margin tectonic setting. Based on the geochemical variation with depth across the R.A.T. and Dipeta and their contact zone, a geochemical fingerprinting suggests that the ratio TiO2/Al2O3 appears to be useful and could be considered as a stratigraphic geochemical maker able to discriminate the R.A.T. and the Dipeta Subgroups during the geological mapping.
- Full Text:
- Date Issued: 2020
Early diagnosis of colorectal cancer using gold nanoparticles : a pilot study
- Authors: Noguda, Njabulo
- Date: 2020
- Subjects: Colon (Anatomy) -- Cancer -- Diagnosis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48577 , vital:40892
- Description: Introduction: Colorectal cancer (CRC) is ranked amongst the top three most diagnosed cancers in humans worldwide. Colorectal cancer is the fourth most common cancer in South Africa and the sixth most common cause of death. If diagnosed during the early stages, the 5year relative survival rate can be as high as 90%. However, in most cases, the diagnosis is only made at a later stage when the cancer has metastasised, as the detection depends on the symptoms and non-specific screening. Many attempts have been made to achieve an early detected of CRC. Aim: To induce CRC in rats to investigate the use of targeted gold nanoparticles (AuNPs) as a diagnostic tool for CRC. Methods: Ten Wistar rats were injected with 1,2-dimethylhydrazine (DMH), 25 µg/Kg bodyweight once per week, for 5 consecutive weeks to induce CRC. This was followed by an incubation period of 22 weeks. At the end of the incubation period, AuNPs were synthesized using Turkevich’s citrate reduction method, and conjugated with peptide p.L. The rats were then injected intraperitoneally with p.L-PEG-AuNPs to detect CRC. Six rats were kept as controls and did not receive any treatment. Results: Five injections of DMH did not induce CRC in the rats. Conclusion: Even though CRC could not be induced using DMH in this study, 14 nm p.L-AuNPs were synthesized successfully.
- Full Text:
- Date Issued: 2020
- Authors: Noguda, Njabulo
- Date: 2020
- Subjects: Colon (Anatomy) -- Cancer -- Diagnosis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48577 , vital:40892
- Description: Introduction: Colorectal cancer (CRC) is ranked amongst the top three most diagnosed cancers in humans worldwide. Colorectal cancer is the fourth most common cancer in South Africa and the sixth most common cause of death. If diagnosed during the early stages, the 5year relative survival rate can be as high as 90%. However, in most cases, the diagnosis is only made at a later stage when the cancer has metastasised, as the detection depends on the symptoms and non-specific screening. Many attempts have been made to achieve an early detected of CRC. Aim: To induce CRC in rats to investigate the use of targeted gold nanoparticles (AuNPs) as a diagnostic tool for CRC. Methods: Ten Wistar rats were injected with 1,2-dimethylhydrazine (DMH), 25 µg/Kg bodyweight once per week, for 5 consecutive weeks to induce CRC. This was followed by an incubation period of 22 weeks. At the end of the incubation period, AuNPs were synthesized using Turkevich’s citrate reduction method, and conjugated with peptide p.L. The rats were then injected intraperitoneally with p.L-PEG-AuNPs to detect CRC. Six rats were kept as controls and did not receive any treatment. Results: Five injections of DMH did not induce CRC in the rats. Conclusion: Even though CRC could not be induced using DMH in this study, 14 nm p.L-AuNPs were synthesized successfully.
- Full Text:
- Date Issued: 2020
Prediction of mass spectra for natural products using an ab initio approach
- Authors: Novokoza, Yolanda
- Date: 2020
- Subjects: Molecular dynamics , Molecular dynamics -- Computer simulation , Mass spectroscopy , Electron impact ionization
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167166 , vital:41443
- Description: Mass spectrometry (MS) is a technique that measures the fragmentation of molecules, dependent on the molecule’s chemical composition and structure, by first introducing a charge on the molecules. The instrument records the mass to charge ratio, but the energy from the ionization process causes the molecule to fragment. The resultant mass spectrum is highly indicative of not only the molecule analyzed, but also its chemical composition. MS is used in research and industry for both routine and research purposes. One such way to ionize molecules for MS is by bombarding the molecule with electrons which is the basis of electron impact mass spectrometry (EIMS). Although EIMS is widely used, prediction of electron impact mass spectra from first principles is a challenging problem due to a need to accurately determine the probability of different fragmentation pathways of a molecule. Ab initio molecular dynamics based methods are able to explore in an automatic fashion the energetically available fragmentation paths thus give reaction mechanisms in an unbiased way. The mass spectra of five molecules have been explored in work-flows leading to the prediction of mass spectra. These molecules include three natural products alpha-hispanolol, PFB oxime derivative and boronolide (for which experimental mass spectra were not available) and two compounds from the NIST database (for which experimental mass spectra were available). For each of these systems many random conformations were generated using the RDKit library. To all conformations random velocities were applied to each atom. Ab initio molecular dynamics was performed on each conformer, using these initial random velocities using CP2K software, at DFTB+ level at a variety of highly raised temperatures (to accelerate the formation of fragments) Fragmentation was monitored by iterating through all bonds, and identifying bond breakages during dynamics. Graph theoretical packages were used then to track distinct fragments generated. For each of these fragments, charges were determined from Mulliken analysis for all atoms on the fragment from the QM calculations and sum of atomic spin densities per fragment was also plotted. The fragment with the greatest charge (corresponding to the formation of a cation fragment) was taken for plotting on the mass spectrum. Finally, from the mass of the fragment and its elemental composition, the isotopic distribution for the fragment was determined, and this distribution was included by addition in to the mass spectrum. For all trajectories, the sum of all isotopic distributions determined the final mass spectrum.
- Full Text:
- Date Issued: 2020
- Authors: Novokoza, Yolanda
- Date: 2020
- Subjects: Molecular dynamics , Molecular dynamics -- Computer simulation , Mass spectroscopy , Electron impact ionization
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167166 , vital:41443
- Description: Mass spectrometry (MS) is a technique that measures the fragmentation of molecules, dependent on the molecule’s chemical composition and structure, by first introducing a charge on the molecules. The instrument records the mass to charge ratio, but the energy from the ionization process causes the molecule to fragment. The resultant mass spectrum is highly indicative of not only the molecule analyzed, but also its chemical composition. MS is used in research and industry for both routine and research purposes. One such way to ionize molecules for MS is by bombarding the molecule with electrons which is the basis of electron impact mass spectrometry (EIMS). Although EIMS is widely used, prediction of electron impact mass spectra from first principles is a challenging problem due to a need to accurately determine the probability of different fragmentation pathways of a molecule. Ab initio molecular dynamics based methods are able to explore in an automatic fashion the energetically available fragmentation paths thus give reaction mechanisms in an unbiased way. The mass spectra of five molecules have been explored in work-flows leading to the prediction of mass spectra. These molecules include three natural products alpha-hispanolol, PFB oxime derivative and boronolide (for which experimental mass spectra were not available) and two compounds from the NIST database (for which experimental mass spectra were available). For each of these systems many random conformations were generated using the RDKit library. To all conformations random velocities were applied to each atom. Ab initio molecular dynamics was performed on each conformer, using these initial random velocities using CP2K software, at DFTB+ level at a variety of highly raised temperatures (to accelerate the formation of fragments) Fragmentation was monitored by iterating through all bonds, and identifying bond breakages during dynamics. Graph theoretical packages were used then to track distinct fragments generated. For each of these fragments, charges were determined from Mulliken analysis for all atoms on the fragment from the QM calculations and sum of atomic spin densities per fragment was also plotted. The fragment with the greatest charge (corresponding to the formation of a cation fragment) was taken for plotting on the mass spectrum. Finally, from the mass of the fragment and its elemental composition, the isotopic distribution for the fragment was determined, and this distribution was included by addition in to the mass spectrum. For all trajectories, the sum of all isotopic distributions determined the final mass spectrum.
- Full Text:
- Date Issued: 2020
Mineralogy, geochemistry and origin of the Neoproterozoic Xaudum iron-formation in Botswana
- Authors: Ntantiso, Mawande
- Date: 2020
- Subjects: Xaudum iron-formation , Iron ores -- Botswana , Formations (Geology) -- Botswana , Mineralogy -- Botswana , Paleoclimatology -- Proterozoic
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167211 , vital:41447
- Description: Banded iron-formations (BIF) formed in three different geological periods in the Earth’s history, namely the Archean, Paleoproterozoic and Neoproterozoic. Each of these periods has a corresponding index BIF type attributed to them. The oldest is the Archean Algoma-type BIF which is typically dominated by smaller-volume BIF deposits associated with volcanic rocks and greenstone belts. The next is the volumetrically far more abundant Superior-type BIF of the Paleoproterozoic lacking any obvious volcanic relation. The youngest BIFs were deposited after a hiatus of a billion years in the Neoproterozoic and are believed to be genetically linked to Marinoan ice-age. The global re-introduction and distribution of BIF in the Neoproterozoic highlights a shift in the Earth’s tectonics, climate, biosphere and ocean chemistry from the older Archean and Paleoproterozoic counterparts. Various models have been postulated by researchers in attempts to explain how Neoproterozoic iron-formations formed. In all the available models, the Snowball Earth Hypothesis initially proposed by Kirshvink (1992) is an overarching concept. In this study, four cores from the Neoproterozoic Xaudum iron-formation (XIF) in Ngamiland, northwest of Botswana, were sampled and analysed following a partnership between Postgraduate Research in Iron and Manganese Ore Resources (PRIMOR) and Tsodilo Resources Ltd. The study sets out to explore the mineralogy and chemistry of XIF in order to determine its origin, constrain the redox conditions in the paleo-basin, assess it in the context of other Neoproterozoic iron-formations and older Archean and Paleoproterozoic iron-formations, and inform metallurgical processing. The mineralogy of XIF consists of magnetite, quartz, amphibole, garnet, biotite and chlorite in decreasing abundance. This mineral assemblage is characteristic of medium grade metamorphosed iron-formations. Algoma and Superior-type BIFs which experienced late-diagenetic and very low-grade metamorphism have a complex mineral assemblage consisting of hematite, magnetite, quartz, and several carbonate (dolomite-ankerite series and siderite) and silicate phases (greenalite, riebeckite and stilpnomelane). The geochemical results show that XIF has higher Mn3O4 and Al2O3 average contents when compared to Algoma and Superior type BIF. The detrital components in XIF correlate with High Field Strength Elements (HFSE) suggesting increased delivery of siliciclastic material during deposition. This trend is comparable to other NIF deposits suggesting a global high input of siliciclastic material into Neoproterozoic paleodepositional environments. This trend is different from Archean and Paleoproterozoic BIF deposits which are close to pure chemical sediments lacking measurable detrital contributions. In the XIF, bulk-rock Mn3O4 and Al2O3 in drillcore SW have higher averages of 2.4 and 2.6 wt. % respectively, compared to the other three cores. The Mn3O4 shows a positive statistical relationship with Co, suggesting that Neoproterozoic oceans and atmosphere were possibly more oxic than in the Archean and Paleoproterozoic. The Mn3O4 shows an antithetic relationship with Fe2O3 suggesting that the paleobasin was chemically heterogeneous in terms of redox conditions, with Fe2O3 depositing presumably in deeper parts removed from a detrital source, and Mn3O4 depositing possibly more proximal to a paleo-shoreline in a shallower setting where there was higher delivery of siliciclastic material from the continent due to correspondingly higher Al2O3 and TiO2 contents. The REE patterns of XIF show positive-sloping trends of depletion in LREE and enrichment in HREE which resemble those of seawater. However, the REE slope becomes a lot flatter and resembles closer the signature of PAAS and adjacent diamictite facies, which agrees with the idea of high siliciclastic input in the paleobasin comparable to other NIF. XIF also appears to lack clear Ce or Eu anomalies. The lack of the former points to the oceans possibly not being oxic enough to drive the fractionation of Ce into Mn oxides like in the modern oceans, or that the Ce behaviour is obscured by the high siliciclastic input in XIF. Similarly, the lack of positive Eu anomaly shows a weak to absent hydrothermal signal into to modern shallow seawater where Fe and Si were sourced, or detritally derived REE contamination. Extensive weathering under hot and humid climate during glacial retreat is shown by the low K2O/Al2O3 ratios and high CIA values ranging from 80-99. Re-glaciation signifies the return of cold and arid and it is represented by high K2O/Al2O3 ratios and low CIA values ranging from 64-78. The previous genetic models of NIF by Klein (1993), Baldwin et al. (2012) and Lechte and Wallace (2015) provide an essential foundation for the development of a XIF genetic model. The genetic model of XIF proposes deposition on an open continental shelf characterized by a steady influx of detrital material. The seawater has been anoxic since the Paleoproterozoic and further induced by basin stagnation due to the ice covering the basin. Two overlapping oxidative stages are assumed for the precipitation of Fe and Mn across lateral redox gradients in the paleobasin. The exact oxidative pathways and mechanisms for the above processes remains unconstrained.
- Full Text:
- Date Issued: 2020
- Authors: Ntantiso, Mawande
- Date: 2020
- Subjects: Xaudum iron-formation , Iron ores -- Botswana , Formations (Geology) -- Botswana , Mineralogy -- Botswana , Paleoclimatology -- Proterozoic
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167211 , vital:41447
- Description: Banded iron-formations (BIF) formed in three different geological periods in the Earth’s history, namely the Archean, Paleoproterozoic and Neoproterozoic. Each of these periods has a corresponding index BIF type attributed to them. The oldest is the Archean Algoma-type BIF which is typically dominated by smaller-volume BIF deposits associated with volcanic rocks and greenstone belts. The next is the volumetrically far more abundant Superior-type BIF of the Paleoproterozoic lacking any obvious volcanic relation. The youngest BIFs were deposited after a hiatus of a billion years in the Neoproterozoic and are believed to be genetically linked to Marinoan ice-age. The global re-introduction and distribution of BIF in the Neoproterozoic highlights a shift in the Earth’s tectonics, climate, biosphere and ocean chemistry from the older Archean and Paleoproterozoic counterparts. Various models have been postulated by researchers in attempts to explain how Neoproterozoic iron-formations formed. In all the available models, the Snowball Earth Hypothesis initially proposed by Kirshvink (1992) is an overarching concept. In this study, four cores from the Neoproterozoic Xaudum iron-formation (XIF) in Ngamiland, northwest of Botswana, were sampled and analysed following a partnership between Postgraduate Research in Iron and Manganese Ore Resources (PRIMOR) and Tsodilo Resources Ltd. The study sets out to explore the mineralogy and chemistry of XIF in order to determine its origin, constrain the redox conditions in the paleo-basin, assess it in the context of other Neoproterozoic iron-formations and older Archean and Paleoproterozoic iron-formations, and inform metallurgical processing. The mineralogy of XIF consists of magnetite, quartz, amphibole, garnet, biotite and chlorite in decreasing abundance. This mineral assemblage is characteristic of medium grade metamorphosed iron-formations. Algoma and Superior-type BIFs which experienced late-diagenetic and very low-grade metamorphism have a complex mineral assemblage consisting of hematite, magnetite, quartz, and several carbonate (dolomite-ankerite series and siderite) and silicate phases (greenalite, riebeckite and stilpnomelane). The geochemical results show that XIF has higher Mn3O4 and Al2O3 average contents when compared to Algoma and Superior type BIF. The detrital components in XIF correlate with High Field Strength Elements (HFSE) suggesting increased delivery of siliciclastic material during deposition. This trend is comparable to other NIF deposits suggesting a global high input of siliciclastic material into Neoproterozoic paleodepositional environments. This trend is different from Archean and Paleoproterozoic BIF deposits which are close to pure chemical sediments lacking measurable detrital contributions. In the XIF, bulk-rock Mn3O4 and Al2O3 in drillcore SW have higher averages of 2.4 and 2.6 wt. % respectively, compared to the other three cores. The Mn3O4 shows a positive statistical relationship with Co, suggesting that Neoproterozoic oceans and atmosphere were possibly more oxic than in the Archean and Paleoproterozoic. The Mn3O4 shows an antithetic relationship with Fe2O3 suggesting that the paleobasin was chemically heterogeneous in terms of redox conditions, with Fe2O3 depositing presumably in deeper parts removed from a detrital source, and Mn3O4 depositing possibly more proximal to a paleo-shoreline in a shallower setting where there was higher delivery of siliciclastic material from the continent due to correspondingly higher Al2O3 and TiO2 contents. The REE patterns of XIF show positive-sloping trends of depletion in LREE and enrichment in HREE which resemble those of seawater. However, the REE slope becomes a lot flatter and resembles closer the signature of PAAS and adjacent diamictite facies, which agrees with the idea of high siliciclastic input in the paleobasin comparable to other NIF. XIF also appears to lack clear Ce or Eu anomalies. The lack of the former points to the oceans possibly not being oxic enough to drive the fractionation of Ce into Mn oxides like in the modern oceans, or that the Ce behaviour is obscured by the high siliciclastic input in XIF. Similarly, the lack of positive Eu anomaly shows a weak to absent hydrothermal signal into to modern shallow seawater where Fe and Si were sourced, or detritally derived REE contamination. Extensive weathering under hot and humid climate during glacial retreat is shown by the low K2O/Al2O3 ratios and high CIA values ranging from 80-99. Re-glaciation signifies the return of cold and arid and it is represented by high K2O/Al2O3 ratios and low CIA values ranging from 64-78. The previous genetic models of NIF by Klein (1993), Baldwin et al. (2012) and Lechte and Wallace (2015) provide an essential foundation for the development of a XIF genetic model. The genetic model of XIF proposes deposition on an open continental shelf characterized by a steady influx of detrital material. The seawater has been anoxic since the Paleoproterozoic and further induced by basin stagnation due to the ice covering the basin. Two overlapping oxidative stages are assumed for the precipitation of Fe and Mn across lateral redox gradients in the paleobasin. The exact oxidative pathways and mechanisms for the above processes remains unconstrained.
- Full Text:
- Date Issued: 2020
The exploration of ARF1 screening assays to determine the drug status of ARF1 in cancer and malaria
- Authors: Ntlantsana, Apelele
- Date: 2020
- Subjects: ADP ribosylation , Golgi apparatus , Guanosine triphosphatase , G proteins , Malariotherapy , Malaria -- Research , Cancer -- Chemotherapy , Malaria -- Chemotherpay
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167232 , vital:41458
- Description: ARF GTPases are key regulators of the secretory and endocytic pathways. ARF1 is involved in the secretory pathway. ARF1 has been implicated in the endoplasmic reticulum to Golgi transport, function of the Golgi apparatus and transport from the trans-Golgi network to endosomes. ARFs cycle between active GTP-bound and inactive GDP-bound conformations. GDP/GTP cycling is regulated by large families of guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). ARF GEFs facilitate the activation of ARFs by mediating the exchange of GDP for GTP, while ARF GAPs terminate ARF function by stimulating the hydrolysis of the terminal phosphate group of GTP. Based on existing evidence gained from gene manipulation and cell biological investigations, ARF1 has been shown to be fundamentally important for cancer cell proliferation and metastasis and may be a promising target for the development of anti-cancer drugs. Additionally, the conservation of ARFs in eukaryotic organisms leads to an interesting question of whether a single drug target can be used to target multiple diseases. In this case, can a human cancer drug employed for cancer therapy be used in anti-malarial drug therapies? To confirm the drug target status of ARFs using chemical validation experiments, novel inhibitory compounds are needed. This requires the development of complex in vitro protein- protein interaction assays that can be used to screen chemical libraries for ARF GTPase inhibitors. In this study, we developed a fluorescence resonance energy transfer (FRET) assay and a novel in vitro colorimetric plate-based assay to detect the activation status of truncated human and Plasmodium falciparum ARF1. In the case of the FRET assay, active (GTP-bound) and inactive (GDP-bound) ARF1 could be distinguished with Z-factor values >0.5, suggesting that further development of the assay format to identify GEF and GAP inhibitors may be feasible. In the case of the colorimetric assay, robust signals could be detected and the assay was useful for detecting the activation status of ARF1. However, although the activation of ARF1 by the Sec7 domains of the BIG1 and ARNO was detectable, signals were not robust enough to employ in screening campaigns.
- Full Text:
- Date Issued: 2020
- Authors: Ntlantsana, Apelele
- Date: 2020
- Subjects: ADP ribosylation , Golgi apparatus , Guanosine triphosphatase , G proteins , Malariotherapy , Malaria -- Research , Cancer -- Chemotherapy , Malaria -- Chemotherpay
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167232 , vital:41458
- Description: ARF GTPases are key regulators of the secretory and endocytic pathways. ARF1 is involved in the secretory pathway. ARF1 has been implicated in the endoplasmic reticulum to Golgi transport, function of the Golgi apparatus and transport from the trans-Golgi network to endosomes. ARFs cycle between active GTP-bound and inactive GDP-bound conformations. GDP/GTP cycling is regulated by large families of guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). ARF GEFs facilitate the activation of ARFs by mediating the exchange of GDP for GTP, while ARF GAPs terminate ARF function by stimulating the hydrolysis of the terminal phosphate group of GTP. Based on existing evidence gained from gene manipulation and cell biological investigations, ARF1 has been shown to be fundamentally important for cancer cell proliferation and metastasis and may be a promising target for the development of anti-cancer drugs. Additionally, the conservation of ARFs in eukaryotic organisms leads to an interesting question of whether a single drug target can be used to target multiple diseases. In this case, can a human cancer drug employed for cancer therapy be used in anti-malarial drug therapies? To confirm the drug target status of ARFs using chemical validation experiments, novel inhibitory compounds are needed. This requires the development of complex in vitro protein- protein interaction assays that can be used to screen chemical libraries for ARF GTPase inhibitors. In this study, we developed a fluorescence resonance energy transfer (FRET) assay and a novel in vitro colorimetric plate-based assay to detect the activation status of truncated human and Plasmodium falciparum ARF1. In the case of the FRET assay, active (GTP-bound) and inactive (GDP-bound) ARF1 could be distinguished with Z-factor values >0.5, suggesting that further development of the assay format to identify GEF and GAP inhibitors may be feasible. In the case of the colorimetric assay, robust signals could be detected and the assay was useful for detecting the activation status of ARF1. However, although the activation of ARF1 by the Sec7 domains of the BIG1 and ARNO was detectable, signals were not robust enough to employ in screening campaigns.
- Full Text:
- Date Issued: 2020
Identification of differentially expressed proteins involved in wheat (Triticum aestivum) resistance against Russian Wheat Aphid (Diuraphis noxia) SA2 using SWATH-MS analysis
- Authors: Ntlokwana, Sitha Emmanuel
- Date: 2020
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18872 , vital:42888
- Description: Wheat (Triticum aestivum) is the second most-consumed cereal crop in the world, second only to maize. In South Africa it is mainly produced in three provinces; the Free State, Western Cape, and the Northen Cape. The average total land area used for wheat cultivation in these three Provinces, is 533 000 hectares, with a resultant annual production of between 1.3 to 2 million tons. The total wheat requirement in South Africa is currently 2.7 million tons according to the production of wheat guidelines published by the Department of Agriculture, Forestry and Fisheries, which is higher than the total annual production. One of the primary reasons that contribute to the lower production levels is insect and pest infestation, in particular, the Russian wheat aphid (Diurophis noxis), which can result in crop loss of up to sixty percent. Russian wheat aphids (RWA) are invasive insects that feed on the phloem of the plant through their specialised thin stylet-like mouthparts and release toxic agents contained in their saliva during feeding, which disrupt cellular functions inside the host plant. This damage leads to symptoms like; chlorosis, necrosis, wilting, stunting and curling of leaves, also known as leaf rolling. This study aimed to identify differentially expressed proteins in resistant and susceptible wheat (Triticum aestivum) cultivars during Russian wheat aphid Biotype South African 2 (RWA-SA2) infestation, in order to identify proteins involved in the wheat resistant mechanism against RWA-SA2. Two wheat cultivars SST398 (resistant to RWA-SA2) and SST356 (susceptible to RWA-SA2) were used, and a total number of 126 plants were planted and divided according to four different harvest times (Control day 0; day 5; day 7 and day 12). The wheat plants were infested with approximately 10 aphids per plant at the three-leaf stage, and placed within an insect cage inside a growth chamber (Conviron, Winnipeg, Canada) set at 24ºC, light intensity of 352 µmol.m-2.sec-1, ambient CO2 levels (410 ppm) and humidity of 60% with a 16h/8h day/night cycle. Wheat leaves were harvested at various time frames, and total protein extraction was performed. The protein samples were reduced with 10 mM dithiothreitol (DTT) and alkylated with 30 mM iodoacetamide (IAA). Sample clean-up and on-bead trypsin digest were performed on megReSyn Hilic columns, over four hours. The resultant peptides were vacuum dried and resuspended in 2% acetonitrile (ACN) before submitting them to LC-MS/MS (SWATH) for analysis. A total number of 611 proteins were differentially expressed, of which 19 were identified to be involved in the resistance response of wheat, and an additional 20 involved in biotic stress responses. This study showed that reactive oxidative species (ROS) such as hydrogen peroxide and hydroxyl radicals (OH-) play a significant role in the early stages of wheat resistance against RWA-SA2 infestation. They are involved in cell wall strengthening, activation of defence genes, involvement of phytohormone signals such as salicylic and jasmonic acid, which also mediates the systemic defences such as, systemic acquired resistance (SAR), leading to the expression of pathogen-related proteins such as (thaumatin-like proteins, oxalate oxidase, defensin, chitinase, and thionins). Although up-regulation of photosynthesis proteins such as (chlorophyll a/b binding protein, photosystem I and II, rubisco and divinyl chlorophyllide a, and 8 vinyl-reductase) were seen on both infested cultivars (susceptible and resistance), higher numbers of these classes of proteins were identified in the resistance cultivar, suggesting that they also play a critical role in resistance. In conclusion, the SWATH analysis used in this study was able to identify numerous proteins involved in the wheat resistance mechanism against RWA-SA2, most of which have not yet been reported to be involved in either biotic stress or RWA-SA2 resistance responses. Future studies are required to biochemically confirm the involvement of these enzymes and proteins the specific metabolic pathways where they are found, in the wheat resistance mechanism against Russian wheat aphid Biotype 2
- Full Text:
- Date Issued: 2020
- Authors: Ntlokwana, Sitha Emmanuel
- Date: 2020
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18872 , vital:42888
- Description: Wheat (Triticum aestivum) is the second most-consumed cereal crop in the world, second only to maize. In South Africa it is mainly produced in three provinces; the Free State, Western Cape, and the Northen Cape. The average total land area used for wheat cultivation in these three Provinces, is 533 000 hectares, with a resultant annual production of between 1.3 to 2 million tons. The total wheat requirement in South Africa is currently 2.7 million tons according to the production of wheat guidelines published by the Department of Agriculture, Forestry and Fisheries, which is higher than the total annual production. One of the primary reasons that contribute to the lower production levels is insect and pest infestation, in particular, the Russian wheat aphid (Diurophis noxis), which can result in crop loss of up to sixty percent. Russian wheat aphids (RWA) are invasive insects that feed on the phloem of the plant through their specialised thin stylet-like mouthparts and release toxic agents contained in their saliva during feeding, which disrupt cellular functions inside the host plant. This damage leads to symptoms like; chlorosis, necrosis, wilting, stunting and curling of leaves, also known as leaf rolling. This study aimed to identify differentially expressed proteins in resistant and susceptible wheat (Triticum aestivum) cultivars during Russian wheat aphid Biotype South African 2 (RWA-SA2) infestation, in order to identify proteins involved in the wheat resistant mechanism against RWA-SA2. Two wheat cultivars SST398 (resistant to RWA-SA2) and SST356 (susceptible to RWA-SA2) were used, and a total number of 126 plants were planted and divided according to four different harvest times (Control day 0; day 5; day 7 and day 12). The wheat plants were infested with approximately 10 aphids per plant at the three-leaf stage, and placed within an insect cage inside a growth chamber (Conviron, Winnipeg, Canada) set at 24ºC, light intensity of 352 µmol.m-2.sec-1, ambient CO2 levels (410 ppm) and humidity of 60% with a 16h/8h day/night cycle. Wheat leaves were harvested at various time frames, and total protein extraction was performed. The protein samples were reduced with 10 mM dithiothreitol (DTT) and alkylated with 30 mM iodoacetamide (IAA). Sample clean-up and on-bead trypsin digest were performed on megReSyn Hilic columns, over four hours. The resultant peptides were vacuum dried and resuspended in 2% acetonitrile (ACN) before submitting them to LC-MS/MS (SWATH) for analysis. A total number of 611 proteins were differentially expressed, of which 19 were identified to be involved in the resistance response of wheat, and an additional 20 involved in biotic stress responses. This study showed that reactive oxidative species (ROS) such as hydrogen peroxide and hydroxyl radicals (OH-) play a significant role in the early stages of wheat resistance against RWA-SA2 infestation. They are involved in cell wall strengthening, activation of defence genes, involvement of phytohormone signals such as salicylic and jasmonic acid, which also mediates the systemic defences such as, systemic acquired resistance (SAR), leading to the expression of pathogen-related proteins such as (thaumatin-like proteins, oxalate oxidase, defensin, chitinase, and thionins). Although up-regulation of photosynthesis proteins such as (chlorophyll a/b binding protein, photosystem I and II, rubisco and divinyl chlorophyllide a, and 8 vinyl-reductase) were seen on both infested cultivars (susceptible and resistance), higher numbers of these classes of proteins were identified in the resistance cultivar, suggesting that they also play a critical role in resistance. In conclusion, the SWATH analysis used in this study was able to identify numerous proteins involved in the wheat resistance mechanism against RWA-SA2, most of which have not yet been reported to be involved in either biotic stress or RWA-SA2 resistance responses. Future studies are required to biochemically confirm the involvement of these enzymes and proteins the specific metabolic pathways where they are found, in the wheat resistance mechanism against Russian wheat aphid Biotype 2
- Full Text:
- Date Issued: 2020
An in silico analysis, purification and partial kinetic characterisation of a serine protease from Gelidium pristoides
- Authors: Ntsata, Zolani
- Date: 2020
- Subjects: Gelidium Proteolytic enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12076 , vital:39149
- Description: The aim of this study was to characterize the protease enzyme (s) from red algae. An in silico analysis of red algae genomes was used to identify gene coding for protease. Protease sequences identified from these genomes were examined for conserved domains, active site and structures. The domain search revealed that the identified sequences were from the five classes of protease enzymes. For function inference, the red algae sequences were aligned to identify the catalytic sites, and the tertiary structures were predicted using homology modelling. An in silico analysis provides an indication of the class and potential functions of the enzymes. However, it cannot predict whether the gene is constitutively expressed in the red algae or under which conditions it may be induced, and it cannot determine the kinetic efficiency of an enzyme against various substrate, or the optimum conditions for the protein activity. Attempts to clone and recombinantly express selected red algae proteases, proved unsuccessful, as the available genomes where from red algae species found mainly in Asia, and the designed primers, therefore, did not amplify a corresponding PCR product from the red algae harvested in South Africa. Crude extracts of red algae collected from Kenton-on-Sea, along the East Coast of South Africa, were screened for protease activity using Benzoyl-Arginine-pNitroAnilide (BApNA) as substrate. The proteases detected in the crude extract were purified using ammonium sulphate precipitation and HiPrep DEAE FF 16/10; CM FF 16/10, and HiPrep Q FF 16/10 columns for ion-exchange chromatography. The HiPrep Q FF 16/10 column yielded active protein, which revealed two bands of 11kDa and 17kDa on SDS-PAGE. It was assumed that these bands represented two subunits of the purified protease. Kinetic characterisation of the purified protease revealed a pH optimum of 9, using BApNA as substrate, a temperature optimum at 60ºC, and sensitivity to temperature when stored above 4ºC. The protease activity was inhibited by Ferric chloride (32%), induced by calcium chloride (156%), no inhibition by magnesium chloride (97%) and slight inhibition by potassium chloride (77%) and manganese chloride (70%). Phenylmethylsulfonyl fluoride (PMSF), a serine protease inhibitor, almost totally inhibited the protease activity, indicating that the protease from red algae was most likely a serine protease. The Km and kcat values were 1.96 µM, and 0.364 s -1 , respectively using BApNA as the substrate. This study revealed that the red algae genome contains numerous genes that encode for proteases from almost all the classes of proteases. A serine protease from the red algae Gelidium pristoides was partially purified and kinetically characterised, confirming that red algae found along the Eastern Coast of South Africa contain genes that express active proteases that may be of medical or industrial interest. Further studies, however, are required to recombinantly express, purify and characterise the numerous proteases encoded by the genes identified in the in silico analysis of this study.
- Full Text:
- Date Issued: 2020
- Authors: Ntsata, Zolani
- Date: 2020
- Subjects: Gelidium Proteolytic enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12076 , vital:39149
- Description: The aim of this study was to characterize the protease enzyme (s) from red algae. An in silico analysis of red algae genomes was used to identify gene coding for protease. Protease sequences identified from these genomes were examined for conserved domains, active site and structures. The domain search revealed that the identified sequences were from the five classes of protease enzymes. For function inference, the red algae sequences were aligned to identify the catalytic sites, and the tertiary structures were predicted using homology modelling. An in silico analysis provides an indication of the class and potential functions of the enzymes. However, it cannot predict whether the gene is constitutively expressed in the red algae or under which conditions it may be induced, and it cannot determine the kinetic efficiency of an enzyme against various substrate, or the optimum conditions for the protein activity. Attempts to clone and recombinantly express selected red algae proteases, proved unsuccessful, as the available genomes where from red algae species found mainly in Asia, and the designed primers, therefore, did not amplify a corresponding PCR product from the red algae harvested in South Africa. Crude extracts of red algae collected from Kenton-on-Sea, along the East Coast of South Africa, were screened for protease activity using Benzoyl-Arginine-pNitroAnilide (BApNA) as substrate. The proteases detected in the crude extract were purified using ammonium sulphate precipitation and HiPrep DEAE FF 16/10; CM FF 16/10, and HiPrep Q FF 16/10 columns for ion-exchange chromatography. The HiPrep Q FF 16/10 column yielded active protein, which revealed two bands of 11kDa and 17kDa on SDS-PAGE. It was assumed that these bands represented two subunits of the purified protease. Kinetic characterisation of the purified protease revealed a pH optimum of 9, using BApNA as substrate, a temperature optimum at 60ºC, and sensitivity to temperature when stored above 4ºC. The protease activity was inhibited by Ferric chloride (32%), induced by calcium chloride (156%), no inhibition by magnesium chloride (97%) and slight inhibition by potassium chloride (77%) and manganese chloride (70%). Phenylmethylsulfonyl fluoride (PMSF), a serine protease inhibitor, almost totally inhibited the protease activity, indicating that the protease from red algae was most likely a serine protease. The Km and kcat values were 1.96 µM, and 0.364 s -1 , respectively using BApNA as the substrate. This study revealed that the red algae genome contains numerous genes that encode for proteases from almost all the classes of proteases. A serine protease from the red algae Gelidium pristoides was partially purified and kinetically characterised, confirming that red algae found along the Eastern Coast of South Africa contain genes that express active proteases that may be of medical or industrial interest. Further studies, however, are required to recombinantly express, purify and characterise the numerous proteases encoded by the genes identified in the in silico analysis of this study.
- Full Text:
- Date Issued: 2020
Do submarine canyons influence the structure and diversity of benthic fish assemblages on the continental shelf edge?
- Nyawo, Mpilonhle Aura June-Rose
- Authors: Nyawo, Mpilonhle Aura June-Rose
- Date: 2020
- Subjects: Submarine valleys , iSimangaliso Wetland Park (South Africa) , Biotic communities -- South Africa -- iSimangaliso Wetland Park , Groundfishes -- South Africa -- iSimangaliso Wetland Park , Marine ecology -- South Africa -- iSimangaliso Wetland Park
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167264 , vital:41462
- Description: Marine ecosystems play an important role in human welfare, such as providing food security and providing social, economic and environmental benefits to an increasing human population. However, due to the deleterious impact of overfishing as well as habitat degradation, pollution and climate change, many marine ecosystems and the substantial biodiversity they support, are under increasing threats. Submarine canyon ecosystems cut into the continental margin in all our oceans and are considered regions of enhanced diversity, abundance and biomass for many marine communities, including fish. In South Africa, the tropical Delagoa Ecoregion is characterised by numerous submarine canyons that are home to coelacanths Latimeria chalumnae, and a variety of commercially important line fish species. However, there is currently a lack of information on the ecological structure and functioning of these canyons, in relation to nearby non-canyon ecosystems. The aim of this thesis was to generate knowledge on the role of submarine canyons in influencing the benthic fish assemblage structure and diversity on the continental shelf and shelf edge within the high-latitude coral reef ecosystems in the tropical Delagoa Ecoregion of South Africa. First, a systematic literature review was conducted to examine the current knowledge on the role of submarine canyons on the benthic fish assemblages occurring on continental margins, as well as outline the trends in canyon research. For the fieldwork component of this thesis, baited remote underwater stereo-video systems were utilised to gather data. The first research chapter, chapter 3, investigated the effect of ecosystem and depth on the diversity and structure of benthic fish assemblages within iSimangaliso Wetland Park in the Delagoa Ecoregion. Data were collected in 2017 from Wright Canyon (canyon ecosystem) and adjacent slope ecosystems around the canyon (non-canyon ecosystem) at depths ranging between 70–240 m. The second research chapter, chapter 4, data were collected in 2018, from 60–100 m depths in three ubmarine canyons (Wright, Diepgat,Levens) and their adjacent habitat within iSimangaliso Wetland Park to investigate the diversity patterns and community structure of benthic fish and cons ider location as a factor. The systematic review showed that canyon research is still very much in its infancy, however more papers are expected to be published in the future. There were clear location associated biases detected, with more than 90% of the canyon research being concentrated in the Mediterranean Sea, while only one study was published from South Africa. Most of the reviewed literature focused on invertebrates, with benthic fish (including cartilaginous fish) being the second most studied taxa. A wide range of methods from both fishery- dependent and fishery-independent categories were used to gather the data of benthic fish from the canyons and adjacent areas. With over 8500 submarine canyons mapped globally, the number of submarine canyon research published and the detected location bias is of great concern. More studies are needed in order to understand the role of submarine canyons on adjacent slope habitats Overall, the results from the research chapters indicated that there were higher a bundances in the canyon ecosystem compared to the non-canyon ecosystem. In contrast, evenness and beta-diversity were higher in the non-canyon ecosystem. Relief, bottom type as well as depth played a major role in explaining the observed abundance and diversity patterns. Both evenness and beta-diversity decreased with increase in depth. The canyon and non-canyon also differed in terms of habitat structure. The canyon ecosystem was characterised by patched reef and reef habitats with high relief whereas the non-canyon ecosystem was characterised by flats and habitats, especially at shallower depths. Additionally, there were clear differences in terms of the fish community structure between the canyon and the non-canyon ecosystem. The heterogeneous and complex habitats of the canyon ecosystem were typified by species such as Epinephelus poecilonotus, Polysteganus coeruleopunctatus and Chrysoblephus puniceus in comparison to the less complex habitats outside the canyons that were preferred by species such as Lagocephalus sceleratus, and Rhinobatos leucospilus. The different locations sampled demonstrated that the canyon effect was not onsistent at all locations, with varying results detected in the different sample locations. This research demonstrates that clea r differences exists between the benthic fish assemblages associated with canyon and non-canyon ecosystems and provides important information on the role of submarine canyons in the iSimangaliso Wetland Park. From this thesis, it is clear that a ‘canyon effect’ exists in the continental shelf and shelf edge. The results suggested that heterogeneity of habitats was the most important environmental factor that differed between the canyon and non-canyon ecosystems and these differences in the habitat were driving the observed patterns. This thesis has provided a reference point, with regards to investigating the role and influence of these canyons on benthic fish assemblages occurring on the continental shelf edge. The information provided by this thesis can ultimately be used in other studies investigating benthic fish assemblages in other submarine canyons within iSimangaliso Wetland Park and the rest of South Africa./
- Full Text:
- Date Issued: 2020
- Authors: Nyawo, Mpilonhle Aura June-Rose
- Date: 2020
- Subjects: Submarine valleys , iSimangaliso Wetland Park (South Africa) , Biotic communities -- South Africa -- iSimangaliso Wetland Park , Groundfishes -- South Africa -- iSimangaliso Wetland Park , Marine ecology -- South Africa -- iSimangaliso Wetland Park
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167264 , vital:41462
- Description: Marine ecosystems play an important role in human welfare, such as providing food security and providing social, economic and environmental benefits to an increasing human population. However, due to the deleterious impact of overfishing as well as habitat degradation, pollution and climate change, many marine ecosystems and the substantial biodiversity they support, are under increasing threats. Submarine canyon ecosystems cut into the continental margin in all our oceans and are considered regions of enhanced diversity, abundance and biomass for many marine communities, including fish. In South Africa, the tropical Delagoa Ecoregion is characterised by numerous submarine canyons that are home to coelacanths Latimeria chalumnae, and a variety of commercially important line fish species. However, there is currently a lack of information on the ecological structure and functioning of these canyons, in relation to nearby non-canyon ecosystems. The aim of this thesis was to generate knowledge on the role of submarine canyons in influencing the benthic fish assemblage structure and diversity on the continental shelf and shelf edge within the high-latitude coral reef ecosystems in the tropical Delagoa Ecoregion of South Africa. First, a systematic literature review was conducted to examine the current knowledge on the role of submarine canyons on the benthic fish assemblages occurring on continental margins, as well as outline the trends in canyon research. For the fieldwork component of this thesis, baited remote underwater stereo-video systems were utilised to gather data. The first research chapter, chapter 3, investigated the effect of ecosystem and depth on the diversity and structure of benthic fish assemblages within iSimangaliso Wetland Park in the Delagoa Ecoregion. Data were collected in 2017 from Wright Canyon (canyon ecosystem) and adjacent slope ecosystems around the canyon (non-canyon ecosystem) at depths ranging between 70–240 m. The second research chapter, chapter 4, data were collected in 2018, from 60–100 m depths in three ubmarine canyons (Wright, Diepgat,Levens) and their adjacent habitat within iSimangaliso Wetland Park to investigate the diversity patterns and community structure of benthic fish and cons ider location as a factor. The systematic review showed that canyon research is still very much in its infancy, however more papers are expected to be published in the future. There were clear location associated biases detected, with more than 90% of the canyon research being concentrated in the Mediterranean Sea, while only one study was published from South Africa. Most of the reviewed literature focused on invertebrates, with benthic fish (including cartilaginous fish) being the second most studied taxa. A wide range of methods from both fishery- dependent and fishery-independent categories were used to gather the data of benthic fish from the canyons and adjacent areas. With over 8500 submarine canyons mapped globally, the number of submarine canyon research published and the detected location bias is of great concern. More studies are needed in order to understand the role of submarine canyons on adjacent slope habitats Overall, the results from the research chapters indicated that there were higher a bundances in the canyon ecosystem compared to the non-canyon ecosystem. In contrast, evenness and beta-diversity were higher in the non-canyon ecosystem. Relief, bottom type as well as depth played a major role in explaining the observed abundance and diversity patterns. Both evenness and beta-diversity decreased with increase in depth. The canyon and non-canyon also differed in terms of habitat structure. The canyon ecosystem was characterised by patched reef and reef habitats with high relief whereas the non-canyon ecosystem was characterised by flats and habitats, especially at shallower depths. Additionally, there were clear differences in terms of the fish community structure between the canyon and the non-canyon ecosystem. The heterogeneous and complex habitats of the canyon ecosystem were typified by species such as Epinephelus poecilonotus, Polysteganus coeruleopunctatus and Chrysoblephus puniceus in comparison to the less complex habitats outside the canyons that were preferred by species such as Lagocephalus sceleratus, and Rhinobatos leucospilus. The different locations sampled demonstrated that the canyon effect was not onsistent at all locations, with varying results detected in the different sample locations. This research demonstrates that clea r differences exists between the benthic fish assemblages associated with canyon and non-canyon ecosystems and provides important information on the role of submarine canyons in the iSimangaliso Wetland Park. From this thesis, it is clear that a ‘canyon effect’ exists in the continental shelf and shelf edge. The results suggested that heterogeneity of habitats was the most important environmental factor that differed between the canyon and non-canyon ecosystems and these differences in the habitat were driving the observed patterns. This thesis has provided a reference point, with regards to investigating the role and influence of these canyons on benthic fish assemblages occurring on the continental shelf edge. The information provided by this thesis can ultimately be used in other studies investigating benthic fish assemblages in other submarine canyons within iSimangaliso Wetland Park and the rest of South Africa./
- Full Text:
- Date Issued: 2020
Formulation and evaluation of liposomal films for buccal delivery of antiretroviral drug
- Authors: Okafor, Nnamdi Ikemefuna
- Date: 2020
- Subjects: Liposomes , Highly active antiretroviral therapy , Antiretroviral agents , HIV infections -- Prevention
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117161 , vital:34485
- Description: The human immune deficiency virus (HIV) infection has been ranked as one of the most devastating microbial infections in the world. This status is a result of the HIV rapid genetic variation, which limits discovery of a vaccine. Use application of antiretroviral therapy (ARVT) in treatment of the disease caused by the HIV infection (known as acquired immunodeficiency syndrome, HIV-AIDS) is frequently compromised by several factors such as the low bioavailability and severe adverse effects associated with the existing antiretroviral drugs (ARVDs). This underlines the need for controlling the pharmacokinetics profiles of ARVD using effective vehicles that can modify drug biodistribution. The same is true for many other conditions, where delivery systems can determine the success or failure of treatment by controlling pharmacokinetic and dynamic properties. The mucosal linings of the oral cavities in addition offer adorable route of administration for systematic drug delivery, improving drug therapeutic performance and often preferred by clinicians and patients. Liposomes are tiny spherical sacs of phospholipid molecules enclosing water droplets, formed (artificially) to carry drugs or other substances into the tissues by crossing and targeting to specific organelles. This work therefore focused on preparation of liposomes and liposomal buccal films (BFs) for potential buccal delivery of efavirenz, an ARVD model endowed with poor solubility and several side effects. The liposomes were prepared by thin film hydration method using crude soybean lecithin (CL) and cholesterol. Efavirenz loaded liposomes were evaluated for particle size, Zeta potential (ZP), morphology, encapsulation efficiency (EE%) and release kinetics studies. The physiochemical properties of the liposomes were also evaluated using Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), energy dispersity spectroscopy (EDS), and Fourier transform infrared (FTIR), while the formulation with the best encapsulation efficiency was used as the solvent medium for the buccal film formation. The buccal films were prepared using solvent casting method, where the liposomal suspension was used as the dispersing medium. The films were optimized for physical properties (thickness, weight variation and folding endurance) using digital Vernier calliper and digital weighing balance. The physiochemical properties of the selected BFs films made of Carbopol (CP) and its combination with Pluronic F127 (PF127) were further characterized using XRD, DSC, FTIR, Transmission Electron Microscopy (TEM), EDS and Scanning Electron Microscopy (SEM). The permeation study of the selected BFs was investigated using Franz diffusion cell. The BFs composed of CP alone or its combination with PF127 demonstrated much better bio-adhesive properties than the films made of other polymers (like Hydroxyl propyl methyl cellulose, HPMC) alone or in combination with PF127. The developed liposome formulation showed high encapsulation 98.8 ± 0.01 % in CL to cholesterol mass ratio of 1:1 and total lipid to drug mass ratio of 2:1. The average particle size 104.82 ± 2.29 nm and Zeta potential -50.33 ± 0.95 mV of these liposomes were found to be attractive for targeted delivery to the HIV infected cells. The CP based BFs (without and with PF127) exhibited good film thickness 0.88 ± 0.10 and 0.76 ± 0.14 mm, with weight uniformity 68.22 ± 1.04 and 86.28 ± 2. 16 mg, satisfactory flexibility values 258 and 321, and slightly acidic pH 6.43 ± 0.76 and 6.32 ± 0.01. The swelling percentage was found to be 50 % for CP film alone and 78 % for CP film with PF127. The cumulative amount of drug that permeated through the buccal epithelium over 24 hours was about 66 % from CP film alone and 75 % from CP film with PF127. Since no evidence of the liposomal encapsulation of EFV have been reported to our knowledge, we find the insights from the present study valuable as a set of preliminary data to encourage further investigations of the encapsulation and delivery of EFV like antiretrovirals for enhanced solubility, site targeting and prolonged release using crude soybean lecithin and mucoadhesive polymers, which holds some added economical values as naturally occurring lipid and polymeric mixtures as a promising delivery systems for buccal delivery of ARVDs.
- Full Text:
- Date Issued: 2020
- Authors: Okafor, Nnamdi Ikemefuna
- Date: 2020
- Subjects: Liposomes , Highly active antiretroviral therapy , Antiretroviral agents , HIV infections -- Prevention
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117161 , vital:34485
- Description: The human immune deficiency virus (HIV) infection has been ranked as one of the most devastating microbial infections in the world. This status is a result of the HIV rapid genetic variation, which limits discovery of a vaccine. Use application of antiretroviral therapy (ARVT) in treatment of the disease caused by the HIV infection (known as acquired immunodeficiency syndrome, HIV-AIDS) is frequently compromised by several factors such as the low bioavailability and severe adverse effects associated with the existing antiretroviral drugs (ARVDs). This underlines the need for controlling the pharmacokinetics profiles of ARVD using effective vehicles that can modify drug biodistribution. The same is true for many other conditions, where delivery systems can determine the success or failure of treatment by controlling pharmacokinetic and dynamic properties. The mucosal linings of the oral cavities in addition offer adorable route of administration for systematic drug delivery, improving drug therapeutic performance and often preferred by clinicians and patients. Liposomes are tiny spherical sacs of phospholipid molecules enclosing water droplets, formed (artificially) to carry drugs or other substances into the tissues by crossing and targeting to specific organelles. This work therefore focused on preparation of liposomes and liposomal buccal films (BFs) for potential buccal delivery of efavirenz, an ARVD model endowed with poor solubility and several side effects. The liposomes were prepared by thin film hydration method using crude soybean lecithin (CL) and cholesterol. Efavirenz loaded liposomes were evaluated for particle size, Zeta potential (ZP), morphology, encapsulation efficiency (EE%) and release kinetics studies. The physiochemical properties of the liposomes were also evaluated using Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), energy dispersity spectroscopy (EDS), and Fourier transform infrared (FTIR), while the formulation with the best encapsulation efficiency was used as the solvent medium for the buccal film formation. The buccal films were prepared using solvent casting method, where the liposomal suspension was used as the dispersing medium. The films were optimized for physical properties (thickness, weight variation and folding endurance) using digital Vernier calliper and digital weighing balance. The physiochemical properties of the selected BFs films made of Carbopol (CP) and its combination with Pluronic F127 (PF127) were further characterized using XRD, DSC, FTIR, Transmission Electron Microscopy (TEM), EDS and Scanning Electron Microscopy (SEM). The permeation study of the selected BFs was investigated using Franz diffusion cell. The BFs composed of CP alone or its combination with PF127 demonstrated much better bio-adhesive properties than the films made of other polymers (like Hydroxyl propyl methyl cellulose, HPMC) alone or in combination with PF127. The developed liposome formulation showed high encapsulation 98.8 ± 0.01 % in CL to cholesterol mass ratio of 1:1 and total lipid to drug mass ratio of 2:1. The average particle size 104.82 ± 2.29 nm and Zeta potential -50.33 ± 0.95 mV of these liposomes were found to be attractive for targeted delivery to the HIV infected cells. The CP based BFs (without and with PF127) exhibited good film thickness 0.88 ± 0.10 and 0.76 ± 0.14 mm, with weight uniformity 68.22 ± 1.04 and 86.28 ± 2. 16 mg, satisfactory flexibility values 258 and 321, and slightly acidic pH 6.43 ± 0.76 and 6.32 ± 0.01. The swelling percentage was found to be 50 % for CP film alone and 78 % for CP film with PF127. The cumulative amount of drug that permeated through the buccal epithelium over 24 hours was about 66 % from CP film alone and 75 % from CP film with PF127. Since no evidence of the liposomal encapsulation of EFV have been reported to our knowledge, we find the insights from the present study valuable as a set of preliminary data to encourage further investigations of the encapsulation and delivery of EFV like antiretrovirals for enhanced solubility, site targeting and prolonged release using crude soybean lecithin and mucoadhesive polymers, which holds some added economical values as naturally occurring lipid and polymeric mixtures as a promising delivery systems for buccal delivery of ARVDs.
- Full Text:
- Date Issued: 2020
Securing software development using developer access control
- Authors: Ongers, Grant
- Date: 2020
- Subjects: Computer software -- Development , Computers -- Access control , Computer security -- Software , Computer networks -- Security measures , Source code (Computer science) , Plug-ins (Computer programs) , Data encryption (Computer science) , Network Access Control , Data Loss Prevention , Google’s BeyondCorp , Confidentiality, Integrity and Availability (CIA) triad
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/149022 , vital:38796
- Description: This research is aimed at software development companies and highlights the unique information security concerns in the context of a non-malicious software developer’s work environment; and furthermore explores an application driven solution which focuses specifically on providing developer environments with access control for source code repositories. In order to achieve that, five goals were defined as discussed in section 1.3. The application designed to provide the developer environment with access control to source code repositories was modelled on lessons taken from the principles of Network Access Control (NAC), Data Loss Prevention (DLP), and Google’s BeyondCorp (GBC) for zero-trust end-user computing. The intention of this research is to provide software developers with maximum access to source code without compromising Confidentiality, as per the Confidentiality, Integrity and Availability (CIA) triad. Employing data gleaned from examining the characteristics of DLP, NAC, and Beyond- Corp—proof-of-concept code was developed to regulate access to the developer’s environment and source code. The system required sufficient flexibility to support the diversity of software development environments. In order to achieve this, a modular design was selected. The system comprised a client side agent and a plug-in-ready server component. The client side agent mounts and dismounts encrypted volumes containing source code. Furthermore, it provides the server with information of the client that is demanded by plug-ins. The server side service provided encryption keys to facilitate the mounting of the volumes and, through plug-ins, asked questions of the client agent to determine whether access should be granted. The solution was then tested with integration and system testing. There were plans to have it used by development teams who were then to be surveyed as to their view on the proof of concept but this proved impossible. The conclusion provides a basis by which organisations that develop software can better balance the two corners of the CIA triad most often in conflict: Confidentiality in terms of their source code against the Availability of the same to developers.
- Full Text:
- Date Issued: 2020
- Authors: Ongers, Grant
- Date: 2020
- Subjects: Computer software -- Development , Computers -- Access control , Computer security -- Software , Computer networks -- Security measures , Source code (Computer science) , Plug-ins (Computer programs) , Data encryption (Computer science) , Network Access Control , Data Loss Prevention , Google’s BeyondCorp , Confidentiality, Integrity and Availability (CIA) triad
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/149022 , vital:38796
- Description: This research is aimed at software development companies and highlights the unique information security concerns in the context of a non-malicious software developer’s work environment; and furthermore explores an application driven solution which focuses specifically on providing developer environments with access control for source code repositories. In order to achieve that, five goals were defined as discussed in section 1.3. The application designed to provide the developer environment with access control to source code repositories was modelled on lessons taken from the principles of Network Access Control (NAC), Data Loss Prevention (DLP), and Google’s BeyondCorp (GBC) for zero-trust end-user computing. The intention of this research is to provide software developers with maximum access to source code without compromising Confidentiality, as per the Confidentiality, Integrity and Availability (CIA) triad. Employing data gleaned from examining the characteristics of DLP, NAC, and Beyond- Corp—proof-of-concept code was developed to regulate access to the developer’s environment and source code. The system required sufficient flexibility to support the diversity of software development environments. In order to achieve this, a modular design was selected. The system comprised a client side agent and a plug-in-ready server component. The client side agent mounts and dismounts encrypted volumes containing source code. Furthermore, it provides the server with information of the client that is demanded by plug-ins. The server side service provided encryption keys to facilitate the mounting of the volumes and, through plug-ins, asked questions of the client agent to determine whether access should be granted. The solution was then tested with integration and system testing. There were plans to have it used by development teams who were then to be surveyed as to their view on the proof of concept but this proved impossible. The conclusion provides a basis by which organisations that develop software can better balance the two corners of the CIA triad most often in conflict: Confidentiality in terms of their source code against the Availability of the same to developers.
- Full Text:
- Date Issued: 2020
Profitable day-neutral strawberry variety and planting date combination for year-round strawberry fruit production in the Southern Cape
- Authors: Parehwa, Patience
- Date: 2020
- Subjects: Strawberries -- Fertilizers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48599 , vital:40894
- Description: South Africa’s strawberry production is currently limited to winter and spring production. Strawberry growers have not been able to extend the growing season for year-round strawberry production primarily due to variety- and climatic limitations. Consumers world-wide, however, demand year-round supply of strawberries on their markets. Delayed planting and robust day-neutral varieties may allow growers to extend the marketing season. To investigate the most profitable variety and planting date combination for season extension in the Southern Cape, trials were conducted at Groeneweide Farm, George. Day-neutral strawberry varieties Monterey, San Andreas and Albion were planted at 30-day intervals from April to September for 3 seasons. They were planted in single layer, standard coir grow-bags at a density of 75 000/ha. Analyses of variance (ANOVA) were performed on vegetative growth stages (crown and runner formation), yield (flowering and fruit yield), fruit quality (fruit mass and total soluble solids content) and gross income. The analysis encompassed variety, month and planting month × variety interaction. ‘Monterey’ significantly outperformed ‘San Andreas’ which in turn significantly (p<0.05) outperformed ‘Albion’ for crown number, flower number, yield, fruit size and margin above cost. ‘San Andreas’ produced significantly fewer runners than ‘Monterey’ and ‘Albion’. ‘Albion’ produced significantly higher TSS followed by ‘Monterey’ and ‘San Andreas’. Over all, the three day-neutral varieties had no significant differences in yield within all planting dates. However, August and September planting dates produced significantly more runners, flowers and higher margin above cost, but significantly smaller fruit and lower total soluble solids (TSS). ‘Monterey’ planted in April and May produced the highest margin above cost and brought earliness to the production window. Together with ‘San Andreas’ planted in August, which extended the harvest season and gave similar margin above cost, it is possible to maximise profitability, extend both ends of the harvest season and also minimise hygiene costs associated with weekly runner removal. Since the strawberry price is very responsive, to quantity supplied, an oversupply out of the normal season, may however lead to lower prices affecting gross income.
- Full Text:
- Date Issued: 2020
- Authors: Parehwa, Patience
- Date: 2020
- Subjects: Strawberries -- Fertilizers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48599 , vital:40894
- Description: South Africa’s strawberry production is currently limited to winter and spring production. Strawberry growers have not been able to extend the growing season for year-round strawberry production primarily due to variety- and climatic limitations. Consumers world-wide, however, demand year-round supply of strawberries on their markets. Delayed planting and robust day-neutral varieties may allow growers to extend the marketing season. To investigate the most profitable variety and planting date combination for season extension in the Southern Cape, trials were conducted at Groeneweide Farm, George. Day-neutral strawberry varieties Monterey, San Andreas and Albion were planted at 30-day intervals from April to September for 3 seasons. They were planted in single layer, standard coir grow-bags at a density of 75 000/ha. Analyses of variance (ANOVA) were performed on vegetative growth stages (crown and runner formation), yield (flowering and fruit yield), fruit quality (fruit mass and total soluble solids content) and gross income. The analysis encompassed variety, month and planting month × variety interaction. ‘Monterey’ significantly outperformed ‘San Andreas’ which in turn significantly (p<0.05) outperformed ‘Albion’ for crown number, flower number, yield, fruit size and margin above cost. ‘San Andreas’ produced significantly fewer runners than ‘Monterey’ and ‘Albion’. ‘Albion’ produced significantly higher TSS followed by ‘Monterey’ and ‘San Andreas’. Over all, the three day-neutral varieties had no significant differences in yield within all planting dates. However, August and September planting dates produced significantly more runners, flowers and higher margin above cost, but significantly smaller fruit and lower total soluble solids (TSS). ‘Monterey’ planted in April and May produced the highest margin above cost and brought earliness to the production window. Together with ‘San Andreas’ planted in August, which extended the harvest season and gave similar margin above cost, it is possible to maximise profitability, extend both ends of the harvest season and also minimise hygiene costs associated with weekly runner removal. Since the strawberry price is very responsive, to quantity supplied, an oversupply out of the normal season, may however lead to lower prices affecting gross income.
- Full Text:
- Date Issued: 2020
An exploration of the overlap between open source threat intelligence and active internet background radiation
- Authors: Pearson, Deon Turner
- Date: 2020
- Subjects: Computer networks -- Security measures , Computer networks -- Monitoring , Malware (Computer software) , TCP/IP (Computer network protocol) , Open source intelligence
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/103802 , vital:32299
- Description: Organisations and individuals are facing increasing persistent threats on the Internet from worms, port scanners, and malicious software (malware). These threats are constantly evolving as attack techniques are discovered. To aid in the detection and prevention of such threats, and to stay ahead of the adversaries conducting the attacks, security specialists are utilising Threat Intelligence (TI) data in their defense strategies. TI data can be obtained from a variety of different sources such as private routers, firewall logs, public archives, and public or private network telescopes. However, at the rate and ease at which TI is produced and published, specifically Open Source Threat Intelligence (OSINT), the quality is dropping, resulting in fragmented, context-less and variable data. This research utilised two sets of TI data, a collection of OSINT and active Internet Background Radiation (IBR). The data was collected over a period of 12 months, from 37 publicly available OSINT datasets and five IBR datasets. Through the identification and analysis of common data between the OSINT and IBR datasets, this research was able to gain insight into how effective OSINT is at detecting and potentially reducing ongoing malicious Internet traffic. As part of this research, a minimal framework for the collection, processing/analysis, and distribution of OSINT was developed and tested. The research focused on exploring areas in common between the two datasets, with the intention of creating an enriched, contextualised, and reduced set of malicious source IP addresses that could be published for consumers to use in their own environment. The findings of this research pointed towards a persistent group of IP addresses observed on both datasets, over the period under research. Using these persistent IP addresses, the research was able to identify specific services being targeted. Amongst these persistent IP addresses were significant packets from Mirai like IoT Malware on port 23/tcp and 2323/tcp as well as general scanning activity on port 445/TCP.
- Full Text:
- Date Issued: 2020
- Authors: Pearson, Deon Turner
- Date: 2020
- Subjects: Computer networks -- Security measures , Computer networks -- Monitoring , Malware (Computer software) , TCP/IP (Computer network protocol) , Open source intelligence
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/103802 , vital:32299
- Description: Organisations and individuals are facing increasing persistent threats on the Internet from worms, port scanners, and malicious software (malware). These threats are constantly evolving as attack techniques are discovered. To aid in the detection and prevention of such threats, and to stay ahead of the adversaries conducting the attacks, security specialists are utilising Threat Intelligence (TI) data in their defense strategies. TI data can be obtained from a variety of different sources such as private routers, firewall logs, public archives, and public or private network telescopes. However, at the rate and ease at which TI is produced and published, specifically Open Source Threat Intelligence (OSINT), the quality is dropping, resulting in fragmented, context-less and variable data. This research utilised two sets of TI data, a collection of OSINT and active Internet Background Radiation (IBR). The data was collected over a period of 12 months, from 37 publicly available OSINT datasets and five IBR datasets. Through the identification and analysis of common data between the OSINT and IBR datasets, this research was able to gain insight into how effective OSINT is at detecting and potentially reducing ongoing malicious Internet traffic. As part of this research, a minimal framework for the collection, processing/analysis, and distribution of OSINT was developed and tested. The research focused on exploring areas in common between the two datasets, with the intention of creating an enriched, contextualised, and reduced set of malicious source IP addresses that could be published for consumers to use in their own environment. The findings of this research pointed towards a persistent group of IP addresses observed on both datasets, over the period under research. Using these persistent IP addresses, the research was able to identify specific services being targeted. Amongst these persistent IP addresses were significant packets from Mirai like IoT Malware on port 23/tcp and 2323/tcp as well as general scanning activity on port 445/TCP.
- Full Text:
- Date Issued: 2020
Investigation into the influence of an alien plant species on the soil microbiota of the sub-Antarctic, Marion Island
- Authors: Pienaar, Robert Daniel
- Date: 2020
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/124039 , vital:35531
- Description: Embargo applied. Embargo period to expire in April of 2021.
- Full Text:
- Date Issued: 2020
- Authors: Pienaar, Robert Daniel
- Date: 2020
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/124039 , vital:35531
- Description: Embargo applied. Embargo period to expire in April of 2021.
- Full Text:
- Date Issued: 2020