Detecting derivative malware samples using deobfuscation-assisted similarity analysis
- Wrench, Peter, Irwin, Barry V W
- Authors: Wrench, Peter , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429494 , vital:72617 , 10.23919/SAIEE.2016.8531543
- Description: The abundance of PHP-based Remote Access Trojans (or web shells) found in the wild has led malware researchers to develop systems capable of tracking and analysing these shells. In the past, such shells were ably classified using signature matching, a process that is currently unable to cope with the sheer volume and variety of web-based malware in circulation. Although a large percentage of newly-created webshell software incorporates portions of code derived from seminal shells such as c99 and r57, they are able to disguise this by making extensive use of obfuscation techniques intended to frustrate any attempts to dissect or reverse engineer the code. This paper presents an approach to shell classification and analysis (based on similarity to a body of known malware) in an attempt to create a comprehensive taxonomy of PHP-based web shells. Several different measures of similarity were used in conjunction with clustering algorithms and visualisation techniques in order to achieve this. Furthermore, an auxiliary component capable of syntactically deobfuscating PHP code is described. This was employed to reverse idiomatic obfuscation constructs used by software authors. It was found that this deobfuscation dramatically increased the observed levels of similarity by exposing additional code for analysis.
- Full Text:
- Date Issued: 2016
- Authors: Wrench, Peter , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429494 , vital:72617 , 10.23919/SAIEE.2016.8531543
- Description: The abundance of PHP-based Remote Access Trojans (or web shells) found in the wild has led malware researchers to develop systems capable of tracking and analysing these shells. In the past, such shells were ably classified using signature matching, a process that is currently unable to cope with the sheer volume and variety of web-based malware in circulation. Although a large percentage of newly-created webshell software incorporates portions of code derived from seminal shells such as c99 and r57, they are able to disguise this by making extensive use of obfuscation techniques intended to frustrate any attempts to dissect or reverse engineer the code. This paper presents an approach to shell classification and analysis (based on similarity to a body of known malware) in an attempt to create a comprehensive taxonomy of PHP-based web shells. Several different measures of similarity were used in conjunction with clustering algorithms and visualisation techniques in order to achieve this. Furthermore, an auxiliary component capable of syntactically deobfuscating PHP code is described. This was employed to reverse idiomatic obfuscation constructs used by software authors. It was found that this deobfuscation dramatically increased the observed levels of similarity by exposing additional code for analysis.
- Full Text:
- Date Issued: 2016
Detection of plant growth enhancing features in psychrotolerant yeasts from Patagonia (Argentina)
- Mestre, María C, Fontenla, Sonia, Bruzone, Marie C, Fernández, Natalia V, Dames, Joanna F
- Authors: Mestre, María C , Fontenla, Sonia , Bruzone, Marie C , Fernández, Natalia V , Dames, Joanna F
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448581 , vital:74744 , https://doi.org/10.1002/jobm.201500728
- Description: This study explores the biotechnological potential for plant production of twelve psychrotolerant yeasts strains from Northwest‐Patagonia. These strains were isolated from different substrates associated with Nothofagus sp. in native forests and Vaccinium sp. in a commercial plantation. Yeasts characterization was performed using in vitro assays to evaluate the production of auxin‐like compounds and siderophores, ability to solubilize inorganic phosphate and to reduce common plant pathogen growth. Strain YF8.3 identified as Aureobasidium pullullans was the main producer of auxin‐like and siderophores compounds. Phosphate solubilization was a characteristic observed by strains L8.12 and CRUB1775 identified as Holtermaniella takashimae and Candida maritima, respectively. Different yeast strains were able to inhibit the growth of Verticillium dahliae PPRI5569 and Pythium aphanidermatum PPRI 9009, but they all failed to inhibit the growth of Fusarium oxysporum PPRI5457. The present study, suggests that yeasts present in different environments in Northwestern‐Patagonian have physiological in vitro features which may influence plant growth. These results are promising for the developing of biological products based on Patagonian yeasts for plant production in cold‐temperate regions.
- Full Text:
- Date Issued: 2016
- Authors: Mestre, María C , Fontenla, Sonia , Bruzone, Marie C , Fernández, Natalia V , Dames, Joanna F
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448581 , vital:74744 , https://doi.org/10.1002/jobm.201500728
- Description: This study explores the biotechnological potential for plant production of twelve psychrotolerant yeasts strains from Northwest‐Patagonia. These strains were isolated from different substrates associated with Nothofagus sp. in native forests and Vaccinium sp. in a commercial plantation. Yeasts characterization was performed using in vitro assays to evaluate the production of auxin‐like compounds and siderophores, ability to solubilize inorganic phosphate and to reduce common plant pathogen growth. Strain YF8.3 identified as Aureobasidium pullullans was the main producer of auxin‐like and siderophores compounds. Phosphate solubilization was a characteristic observed by strains L8.12 and CRUB1775 identified as Holtermaniella takashimae and Candida maritima, respectively. Different yeast strains were able to inhibit the growth of Verticillium dahliae PPRI5569 and Pythium aphanidermatum PPRI 9009, but they all failed to inhibit the growth of Fusarium oxysporum PPRI5457. The present study, suggests that yeasts present in different environments in Northwestern‐Patagonian have physiological in vitro features which may influence plant growth. These results are promising for the developing of biological products based on Patagonian yeasts for plant production in cold‐temperate regions.
- Full Text:
- Date Issued: 2016
Determinants of economic growth in China: 1978-2013
- Authors: Sipuka, Msingathi
- Date: 2016
- Subjects: China -- Economic conditions -- 1976-2000 , Economic development -- China
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: http://hdl.handle.net/10948/11181 , vital:26892
- Description: On 1 October 1949, the Communist Party of China under the leadership of Mao Zedong proclaimed the establishment of the People’s Republic of China. Mao was to lead the People’s Republic of China for the next twenty seven years until his death in 1976. During this twenty seven year period under Mao’s leadership the Communist Party of China consolidated its position as the leader of Chinese society and in so doing consolidated communist ideology as the central perspective that guided social and economic planning in China. In 1978, two years after Mao’s death, Deng Xiaping assumed the leadership of the Communist Party of China and this period marked the beginning of far reaching economic and social reforms in China. Over the next thirty years these reforms were to transform China’s economy from the tenth largest to the second largest in the world by the end of 2013. During this period China grew its manufacturing base to the extent that the country has become the world’s largest manufacturer and the world’s leading exporter. This transformation of China’s economy has translated to the country experiencing a period of high levels of economic growth over a sustained period of over 30 years. Estimates suggest that the country’s gross domestic product grew at an average annual rate of nearly 10% over a thirty year period from 1978. These high levels of economic growth have significantly contributed to the overall reduction of poverty levels in the country, with some estimates suggesting that between 300 million to 500 million of the country’s citizens have been lifted out of poverty over a period of thirty years. China’s economic growth has had an impact beyond its own borders, as growth in many developing countries has been inextricably linked to developments in the Chinese economy in particular its demand for raw materials.For developing countries that continue to grapple with high levels of poverty among its citizens, China’s experience of lifting such large numbers of its own citizens out of poverty at the back of high levels of economic growth over a period of thirty years must serve as a basis for some learnings. The primary purpose of this research is aimed at contributing towards building the basis for such learnings, particularly with regards to building an understanding of how China has been able to grow its economy at such high levels over a sustained period of time. This research aims to identify the determinants of China’s growth post 1978. The determinants of growth are studied particularly from 1978 because the year marks the beginning of the period of economic reforms.
- Full Text:
- Date Issued: 2016
- Authors: Sipuka, Msingathi
- Date: 2016
- Subjects: China -- Economic conditions -- 1976-2000 , Economic development -- China
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: http://hdl.handle.net/10948/11181 , vital:26892
- Description: On 1 October 1949, the Communist Party of China under the leadership of Mao Zedong proclaimed the establishment of the People’s Republic of China. Mao was to lead the People’s Republic of China for the next twenty seven years until his death in 1976. During this twenty seven year period under Mao’s leadership the Communist Party of China consolidated its position as the leader of Chinese society and in so doing consolidated communist ideology as the central perspective that guided social and economic planning in China. In 1978, two years after Mao’s death, Deng Xiaping assumed the leadership of the Communist Party of China and this period marked the beginning of far reaching economic and social reforms in China. Over the next thirty years these reforms were to transform China’s economy from the tenth largest to the second largest in the world by the end of 2013. During this period China grew its manufacturing base to the extent that the country has become the world’s largest manufacturer and the world’s leading exporter. This transformation of China’s economy has translated to the country experiencing a period of high levels of economic growth over a sustained period of over 30 years. Estimates suggest that the country’s gross domestic product grew at an average annual rate of nearly 10% over a thirty year period from 1978. These high levels of economic growth have significantly contributed to the overall reduction of poverty levels in the country, with some estimates suggesting that between 300 million to 500 million of the country’s citizens have been lifted out of poverty over a period of thirty years. China’s economic growth has had an impact beyond its own borders, as growth in many developing countries has been inextricably linked to developments in the Chinese economy in particular its demand for raw materials.For developing countries that continue to grapple with high levels of poverty among its citizens, China’s experience of lifting such large numbers of its own citizens out of poverty at the back of high levels of economic growth over a period of thirty years must serve as a basis for some learnings. The primary purpose of this research is aimed at contributing towards building the basis for such learnings, particularly with regards to building an understanding of how China has been able to grow its economy at such high levels over a sustained period of time. This research aims to identify the determinants of China’s growth post 1978. The determinants of growth are studied particularly from 1978 because the year marks the beginning of the period of economic reforms.
- Full Text:
- Date Issued: 2016
Determinants of economic growth in South Africa: an economic analysis of the Keynesian macroeconomic model
- Authors: Nach, Marida Nephertiti
- Date: 2016
- Subjects: South Africa -- Economic conditions Economic development -- South Africa Finance -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/12459 , vital:27068
- Description: A country’s performance is commonly measured by its Gross Domestic Product (GDP). The Gross Domestic Product in Developing Countries (DCs) can be seen confusing and unbalanced, with regular and unconditional falls and booms. This study aims at examining the factors that affect the Gross Domestic Product (GDP) of Developing Countries (DCs) whereby South Africa is being selected as a representative. An econometric analysis of the Keynesian model is adopted to test the South African Gross Domestic Product (GDP) over a decade (10 years). The methodology conducted uses quarterly time series data from the South African Reserve Bank (SARB) where the South African Gross Domestic Product (GDP) is modelled as a function of consumption expenditure, domestic investment, government spending and export/import of the country. This is in order to determine which of these factors best explain South African economic growth dynamics. The variables in the model are tested for stationary and the result shows that the variables become stationary at 1st difference, except for consumption which become stationary at 2nd difference. The Ordinary Least Squares (OLS) results confirm that consumption, investment, government spending and net export all have a positive impact on Gross Domestic Product (GDP). The findings suggest that the South African Gross Domestic Product is mainly influenced by consumption, followed by investment. In the recommendation context, the study recommends that South Africa should continue to maintain price stability while at the same time endeavour to attract more investment to the country. Moreover, Developing Countries need to maintain a fiscal discipline without necessarily losing sight of the international dynamics. For further areas of studies, the study recommends more analysis on macroeconomic policies that are comprehensive and can cover all aspects related to the Keynesian model of economic growth. Finally, it is necessary to remind that the findings and recommendations drawn from the study are limited to the concept of South Africa and are based only on the results from the empirical analysis conducted.
- Full Text:
- Date Issued: 2016
- Authors: Nach, Marida Nephertiti
- Date: 2016
- Subjects: South Africa -- Economic conditions Economic development -- South Africa Finance -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/12459 , vital:27068
- Description: A country’s performance is commonly measured by its Gross Domestic Product (GDP). The Gross Domestic Product in Developing Countries (DCs) can be seen confusing and unbalanced, with regular and unconditional falls and booms. This study aims at examining the factors that affect the Gross Domestic Product (GDP) of Developing Countries (DCs) whereby South Africa is being selected as a representative. An econometric analysis of the Keynesian model is adopted to test the South African Gross Domestic Product (GDP) over a decade (10 years). The methodology conducted uses quarterly time series data from the South African Reserve Bank (SARB) where the South African Gross Domestic Product (GDP) is modelled as a function of consumption expenditure, domestic investment, government spending and export/import of the country. This is in order to determine which of these factors best explain South African economic growth dynamics. The variables in the model are tested for stationary and the result shows that the variables become stationary at 1st difference, except for consumption which become stationary at 2nd difference. The Ordinary Least Squares (OLS) results confirm that consumption, investment, government spending and net export all have a positive impact on Gross Domestic Product (GDP). The findings suggest that the South African Gross Domestic Product is mainly influenced by consumption, followed by investment. In the recommendation context, the study recommends that South Africa should continue to maintain price stability while at the same time endeavour to attract more investment to the country. Moreover, Developing Countries need to maintain a fiscal discipline without necessarily losing sight of the international dynamics. For further areas of studies, the study recommends more analysis on macroeconomic policies that are comprehensive and can cover all aspects related to the Keynesian model of economic growth. Finally, it is necessary to remind that the findings and recommendations drawn from the study are limited to the concept of South Africa and are based only on the results from the empirical analysis conducted.
- Full Text:
- Date Issued: 2016
Determinants of household savings in South Africa
- Authors: Malindini, Kholiswa
- Date: 2016
- Subjects: Cost and standard of living -- South Africa , Home economics -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10948/8436 , vital:26356
- Description: This study empirically evaluates the determinant of household savings in South Africa (1985- 2013). The study used co-integration and Vector Error Correction Mechanism to determine the relationship between household savings and the selected explanatory variables. The study made use of a quarterly time series data sets from the SARB quarterly bulletin. The long-run relationship between savings and its determinants was examined using the procedure suggested in the literature by Johansen. The results of the co-integration tests suggest that there is a long-run relationship between savings and household wealth. The results suggest that wealth is a main determinant of household savings in the long run. However, the impulse response function and the variance decomposition indicated that household debt is dominant in explaining the variations in household savings better than other explanatory variables confirm. On the other hand, household debt, household disposable income and cpi (inflation) and interest rates have negative effects on household savings in the long run. Further, the estimated results revealed that disposable income, interest rate and inflation have statistically significant influence on household savings in South Africa. The implication of the results obtained from impulse response and variance decomposition is that South Africa has liberalized its financial sector to a large extent over the past decade such that households are over indebted. The main reasons for the decline in savings in South Africa is easy availability of Credit which encouraged consumers to take out loans, the rising house prices which encouraged consumers to borrow because of their positive wealth effect, Cultural/Social trends encouraging an attitude of borrowing and spending and lastly low interest rates (both in nominal and real terms). To this end, the study suggests that the South African National Credit Regulator conduct a credit audit to spot-check credit providers’ compliance with the provisions on reckless credit and over-indebtedness. More focus should be placed on indirect measures for preventing over-indebtedness, for example education. It is recommended that governmental or private organisations should set up educational programmes to improve information and advice on the risks attached to consumer credit. It is further suggested these programmes focus on money management for use in schools be made compulsory so as to raise awareness levels and establish financial literacy from an early age. This recommendation is based on the principle that prevention is better than cure.
- Full Text:
- Date Issued: 2016
- Authors: Malindini, Kholiswa
- Date: 2016
- Subjects: Cost and standard of living -- South Africa , Home economics -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10948/8436 , vital:26356
- Description: This study empirically evaluates the determinant of household savings in South Africa (1985- 2013). The study used co-integration and Vector Error Correction Mechanism to determine the relationship between household savings and the selected explanatory variables. The study made use of a quarterly time series data sets from the SARB quarterly bulletin. The long-run relationship between savings and its determinants was examined using the procedure suggested in the literature by Johansen. The results of the co-integration tests suggest that there is a long-run relationship between savings and household wealth. The results suggest that wealth is a main determinant of household savings in the long run. However, the impulse response function and the variance decomposition indicated that household debt is dominant in explaining the variations in household savings better than other explanatory variables confirm. On the other hand, household debt, household disposable income and cpi (inflation) and interest rates have negative effects on household savings in the long run. Further, the estimated results revealed that disposable income, interest rate and inflation have statistically significant influence on household savings in South Africa. The implication of the results obtained from impulse response and variance decomposition is that South Africa has liberalized its financial sector to a large extent over the past decade such that households are over indebted. The main reasons for the decline in savings in South Africa is easy availability of Credit which encouraged consumers to take out loans, the rising house prices which encouraged consumers to borrow because of their positive wealth effect, Cultural/Social trends encouraging an attitude of borrowing and spending and lastly low interest rates (both in nominal and real terms). To this end, the study suggests that the South African National Credit Regulator conduct a credit audit to spot-check credit providers’ compliance with the provisions on reckless credit and over-indebtedness. More focus should be placed on indirect measures for preventing over-indebtedness, for example education. It is recommended that governmental or private organisations should set up educational programmes to improve information and advice on the risks attached to consumer credit. It is further suggested these programmes focus on money management for use in schools be made compulsory so as to raise awareness levels and establish financial literacy from an early age. This recommendation is based on the principle that prevention is better than cure.
- Full Text:
- Date Issued: 2016
Determinants of participation in beekeeping and its contribution to rural household income: the case of O. R. Tambo Municipality, Eastern Cape Province, South Africa
- Authors: Ncetani, Nelisiwe
- Date: 2016
- Subjects: Beekeepers -- South Africa -- Eastern Cape Sustainable living -- South Africa -- Eastern Cape Home economics, Rural -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/1486 , vital:27299
- Description: This dissertation explores determinants and perceptions to participation in beekeeping by households’ as well as its contribution to household income. This is in a context that smallholder farmers’ participation is reported to be very low, despite several claimed benefits of beekeeping. Moreover, despite receiving substantial endorsements as a resilient climate-smart rural livelihood, off-farm, forest, non-timber diversification strategy; the uptake of beekeeping by smallholder farmers in the Eastern Cape Province of South Africa still remains very low. Against this background, this study used cross-sectional survey data to gauge smallholder farmers’ perceptions and factors that influence their participation in beekeeping using a binary regression model; further, it measured the contribution of beekeeping to rural household income using a linear regression model. Descriptive statistics revealed that majority of the people from the study area have positive perceptions regarding beekeeping. Regression estimates further indicate that beekeeping is mostly conditioned by shared perceptions, institutional and socio-economic factors that are worth targeting to promote the uptake of beekeeping as a livelihood. Public policies that influence the institutional framework (extension, credit and market) in favour of beekeeping are more likely to promote participation in beekeeping activities. Also, more research on the documentation and benefits of beekeeping supported by investments targeting educational campaigns towards promoting positive attitudes and dispelling fears and myths surrounding beekeeping as an enterprise, will also promote the participation of smallholder farmers in beekeeping. Regression estimates for determinants of household income revealed a significant positive contribution of beekeeping to household income, education, gender and age. Promotion of beekeeping may therefore address household income that is worth targeting to address rural poverty. The study therefore concludes that to fully unlock the income potential of beekeeping for smallholder farmers, development agencies need to address several negative perceptions and institutional factors that affect beekeeping participation, while more research is required to quantify the claimed benefits of beekeeping, given their positive potential to promote farmers’ interests in beekeeping.
- Full Text:
- Date Issued: 2016
- Authors: Ncetani, Nelisiwe
- Date: 2016
- Subjects: Beekeepers -- South Africa -- Eastern Cape Sustainable living -- South Africa -- Eastern Cape Home economics, Rural -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/1486 , vital:27299
- Description: This dissertation explores determinants and perceptions to participation in beekeeping by households’ as well as its contribution to household income. This is in a context that smallholder farmers’ participation is reported to be very low, despite several claimed benefits of beekeeping. Moreover, despite receiving substantial endorsements as a resilient climate-smart rural livelihood, off-farm, forest, non-timber diversification strategy; the uptake of beekeeping by smallholder farmers in the Eastern Cape Province of South Africa still remains very low. Against this background, this study used cross-sectional survey data to gauge smallholder farmers’ perceptions and factors that influence their participation in beekeeping using a binary regression model; further, it measured the contribution of beekeeping to rural household income using a linear regression model. Descriptive statistics revealed that majority of the people from the study area have positive perceptions regarding beekeeping. Regression estimates further indicate that beekeeping is mostly conditioned by shared perceptions, institutional and socio-economic factors that are worth targeting to promote the uptake of beekeeping as a livelihood. Public policies that influence the institutional framework (extension, credit and market) in favour of beekeeping are more likely to promote participation in beekeeping activities. Also, more research on the documentation and benefits of beekeeping supported by investments targeting educational campaigns towards promoting positive attitudes and dispelling fears and myths surrounding beekeeping as an enterprise, will also promote the participation of smallholder farmers in beekeeping. Regression estimates for determinants of household income revealed a significant positive contribution of beekeeping to household income, education, gender and age. Promotion of beekeeping may therefore address household income that is worth targeting to address rural poverty. The study therefore concludes that to fully unlock the income potential of beekeeping for smallholder farmers, development agencies need to address several negative perceptions and institutional factors that affect beekeeping participation, while more research is required to quantify the claimed benefits of beekeeping, given their positive potential to promote farmers’ interests in beekeeping.
- Full Text:
- Date Issued: 2016
Determining budgeting skills of government social grant holders
- Authors: Matanga, Sive
- Date: 2016
- Subjects: Budgets, Personal -- South Africa , Social security -- South Africa Grants-in-aid -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/18454 , vital:28647
- Description: The lack of budgeting skills in Government Social Grant recipients has significantly added to an inability in many of the grant recipients to address the existing poverty in their households. This situation has been exacerbated due to exploitation of social grant recipients by illegal money lenders charging excessively high interest rates trapping grant recipients in a vicious cycle of perpetuating debt. In remote rural areas poverty and lack of literacy and numeracy skills go hand in hand. Psycho-social and economic factors play a role in grant recipients’ poor budgeting and financial decision making skills, contributing to them falling into debt in the first place. Aggravating the situation is legislation that limits access to financial resources of those without employment, rendering illegal money lenders the financial entity providing finance by default. The research was conducted in a poor rural area around Tarkastad, Eastern Cape and sought to identify challenges caused by, amongst others, the lack of decent education, poverty and poor budgeting skills, all negatively influencing different social grant holders. Analysis of data from this qualitative study took place by means of a thematic classification against the background of a critical theoretical framework. The researcher believes that this study shed light on issues surrounding exploitation by illegal, unregistered money lenders and that the suggested recommendations, if implemented, may bring about a change in lending patterns and saving behaviour of communities in remote areas.
- Full Text:
- Date Issued: 2016
- Authors: Matanga, Sive
- Date: 2016
- Subjects: Budgets, Personal -- South Africa , Social security -- South Africa Grants-in-aid -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/18454 , vital:28647
- Description: The lack of budgeting skills in Government Social Grant recipients has significantly added to an inability in many of the grant recipients to address the existing poverty in their households. This situation has been exacerbated due to exploitation of social grant recipients by illegal money lenders charging excessively high interest rates trapping grant recipients in a vicious cycle of perpetuating debt. In remote rural areas poverty and lack of literacy and numeracy skills go hand in hand. Psycho-social and economic factors play a role in grant recipients’ poor budgeting and financial decision making skills, contributing to them falling into debt in the first place. Aggravating the situation is legislation that limits access to financial resources of those without employment, rendering illegal money lenders the financial entity providing finance by default. The research was conducted in a poor rural area around Tarkastad, Eastern Cape and sought to identify challenges caused by, amongst others, the lack of decent education, poverty and poor budgeting skills, all negatively influencing different social grant holders. Analysis of data from this qualitative study took place by means of a thematic classification against the background of a critical theoretical framework. The researcher believes that this study shed light on issues surrounding exploitation by illegal, unregistered money lenders and that the suggested recommendations, if implemented, may bring about a change in lending patterns and saving behaviour of communities in remote areas.
- Full Text:
- Date Issued: 2016
Determining reasonableness in the light of Sidumo
- Govender, Mogisvaree Murugan
- Authors: Govender, Mogisvaree Murugan
- Date: 2016
- Subjects: Labor laws and legislation -- South Africa Employees -- Law and legislation -- South Africa Law -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/11648 , vital:26947
- Description: The primary purpose of this treatise is to consider the development, analysis and application of the review test in relation to arbitration awards which is set out in the Constitutional Court (CC) judgment of Sidumo & Another v Rustenburg Platinum Mines Ltd & Others (Sidumo).1 This judgment has already had significant implications for employers and employees alike and will continue to do so in the future. Many lawyers, trade unions and employees launch or oppose review applications in the Labour Court on behalf of employers or employees. In observing this litigation process, it became clear that practitioners make two fundamental mistakes. Firstly they do not appreciate the distinction between reviews and appeals and / or, secondly, they misconstrue the Sidumo test in seeking to review or defend an arbitration award. This causes serious prejudice to their clients and results in delays in labour dispute resolution which is contrary to the spirit and purpose of the Labour Relations Act,2 as amended (LRA). The application of the Constitution of the Republic of South Africa,3 legislation and case law is fundamental to the review of arbitration awards and the role of arbitrators in that process. The common thread is the notion of “reasonableness” and “fairness” which has been and continues to be of significant importance in the assessment of arbitration awards. During the course of this research paper, reference is been made to the Constitution, legislation, case law, academic papers and journal articles. The references are mostly precedent setting and authoritative in relation to reviewable irregularities in arbitration awards. The purpose of this paper is guide and assist labour court practitioners to analyse arbitration awards and identify reviewable irregularities in order to determine whether it meets the bandwidth of reasonableness within the context of the Constitution and LRA. In doing so, practitioners will be able to successfully review awards without unduly delaying the dispute resolution process. During the research process, one of the important findings was that there has been inconsistent jurisprudence relating to the application of the grounds of review and the review test itself as per Sidumo which blurred the distinction between reviews and appeals. Many review applications failed to attack the reasonableness of the decision of the commissioner, but rather focused on the cogency of the evidence presented at the arbitration and thereby incorrectly invoking an appeal instead of a review. A further challenge was that the jurisprudence created a perception amongst practitioners that there was a decline in the Sidumo test. This approach was inherently incorrect and recent judgments have clarified and upheld the Sidumo test in review applications.4 The recent landmark judgments by the Supreme Court of Appeal (SCA) clarified that reasonableness was not a separate ground of review but was to be suffused with the grounds of review set out in section 145(2)(a) of the LRA.5 Lastly, Sidumo did not postulate the bandwidth of reasonableness and it was left to the courts to determine the extent of judicial interference. There are various factors to be considered and CC judgments have provided much needed guidance on how to determine reasonableness. In essence, a wrong decision per se is not reviewable. At best, erroneous reasons or lack of proper reasons may serve as evidence for a reviewable ground that will together with other considerations require compelling proof to justify a court’s interpretation that the decision reached is not one that a reasonable decision could have reached.7 In order to obtain an award on the basis of the Sidumo test, the 4 Andre Herholdt v Nedbank [2013] 11 BLLR 1075 (SCA); Goldfields Mining South Africa (Pty) Ltd v CCMA [2014] BLLR 20 (LAC). applicant must thus assail not only the commissioner’s reasons, but also the result of the award.
- Full Text:
- Date Issued: 2016
- Authors: Govender, Mogisvaree Murugan
- Date: 2016
- Subjects: Labor laws and legislation -- South Africa Employees -- Law and legislation -- South Africa Law -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/11648 , vital:26947
- Description: The primary purpose of this treatise is to consider the development, analysis and application of the review test in relation to arbitration awards which is set out in the Constitutional Court (CC) judgment of Sidumo & Another v Rustenburg Platinum Mines Ltd & Others (Sidumo).1 This judgment has already had significant implications for employers and employees alike and will continue to do so in the future. Many lawyers, trade unions and employees launch or oppose review applications in the Labour Court on behalf of employers or employees. In observing this litigation process, it became clear that practitioners make two fundamental mistakes. Firstly they do not appreciate the distinction between reviews and appeals and / or, secondly, they misconstrue the Sidumo test in seeking to review or defend an arbitration award. This causes serious prejudice to their clients and results in delays in labour dispute resolution which is contrary to the spirit and purpose of the Labour Relations Act,2 as amended (LRA). The application of the Constitution of the Republic of South Africa,3 legislation and case law is fundamental to the review of arbitration awards and the role of arbitrators in that process. The common thread is the notion of “reasonableness” and “fairness” which has been and continues to be of significant importance in the assessment of arbitration awards. During the course of this research paper, reference is been made to the Constitution, legislation, case law, academic papers and journal articles. The references are mostly precedent setting and authoritative in relation to reviewable irregularities in arbitration awards. The purpose of this paper is guide and assist labour court practitioners to analyse arbitration awards and identify reviewable irregularities in order to determine whether it meets the bandwidth of reasonableness within the context of the Constitution and LRA. In doing so, practitioners will be able to successfully review awards without unduly delaying the dispute resolution process. During the research process, one of the important findings was that there has been inconsistent jurisprudence relating to the application of the grounds of review and the review test itself as per Sidumo which blurred the distinction between reviews and appeals. Many review applications failed to attack the reasonableness of the decision of the commissioner, but rather focused on the cogency of the evidence presented at the arbitration and thereby incorrectly invoking an appeal instead of a review. A further challenge was that the jurisprudence created a perception amongst practitioners that there was a decline in the Sidumo test. This approach was inherently incorrect and recent judgments have clarified and upheld the Sidumo test in review applications.4 The recent landmark judgments by the Supreme Court of Appeal (SCA) clarified that reasonableness was not a separate ground of review but was to be suffused with the grounds of review set out in section 145(2)(a) of the LRA.5 Lastly, Sidumo did not postulate the bandwidth of reasonableness and it was left to the courts to determine the extent of judicial interference. There are various factors to be considered and CC judgments have provided much needed guidance on how to determine reasonableness. In essence, a wrong decision per se is not reviewable. At best, erroneous reasons or lack of proper reasons may serve as evidence for a reviewable ground that will together with other considerations require compelling proof to justify a court’s interpretation that the decision reached is not one that a reasonable decision could have reached.7 In order to obtain an award on the basis of the Sidumo test, the 4 Andre Herholdt v Nedbank [2013] 11 BLLR 1075 (SCA); Goldfields Mining South Africa (Pty) Ltd v CCMA [2014] BLLR 20 (LAC). applicant must thus assail not only the commissioner’s reasons, but also the result of the award.
- Full Text:
- Date Issued: 2016
Developing a lean and green manufacturing plan for the newspaper printing industry - considering the Rising Sun Printers
- Authors: Maharaj, Avish
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:867 , http://hdl.handle.net/10962/d1021249
- Description: This research is focused on lean and green manufacturing using a printing company in South Africa as a case study focusing on their printing division. The reason for addressing the printing division of the company was to develop a lean and green manufacturing plan to address the concerns of resource utilisation and waste disposal in the printing division. The research looked at the concept of lean and green individually as well as together and by analysing the relationship between the two concepts. The outcome was that environmental “green” waste is embedded in the seven types of lean waste which is overproduction, waiting, transport, inappropriate processing, unnecessary inventory, unnecessary motion and waste due to defects (Moreira, Alves and Sousa, 2010 cited in Pampanelli, Found and Bernardes, 2014). It was found that the company under consideration had not been familiar with these concepts but learnt and understood the value it could bring to the company. The research concludes with the plan using the 5S tool to reduce the seven types of waste linked to lean and green manufacturing.
- Full Text:
- Date Issued: 2016
- Authors: Maharaj, Avish
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:867 , http://hdl.handle.net/10962/d1021249
- Description: This research is focused on lean and green manufacturing using a printing company in South Africa as a case study focusing on their printing division. The reason for addressing the printing division of the company was to develop a lean and green manufacturing plan to address the concerns of resource utilisation and waste disposal in the printing division. The research looked at the concept of lean and green individually as well as together and by analysing the relationship between the two concepts. The outcome was that environmental “green” waste is embedded in the seven types of lean waste which is overproduction, waiting, transport, inappropriate processing, unnecessary inventory, unnecessary motion and waste due to defects (Moreira, Alves and Sousa, 2010 cited in Pampanelli, Found and Bernardes, 2014). It was found that the company under consideration had not been familiar with these concepts but learnt and understood the value it could bring to the company. The research concludes with the plan using the 5S tool to reduce the seven types of waste linked to lean and green manufacturing.
- Full Text:
- Date Issued: 2016
Developing a Multi Platform Countermeasure to Ensure a Secure Home
- Frieslaar, Ibraheem, Irwin, Barry V W
- Authors: Frieslaar, Ibraheem , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427772 , vital:72461 , https://www.researchgate.net/profile/Ibraheem-Fries-laar/publication/312219190_Developing_a_Multi_Platform_Countermeasure_to_Ensure_a_Secure_Home/links/587747d508ae8fce492fb5e2/Developing-a-Multi-Platform-Countermeasure-to-Ensure-a-Secure-Home.pdf
- Description: This research proposes an investigation into the side channel analysis attacks against the AES algorithm on high powered devices. Currently the research field into this aspect is fairly new and there is room for more information to be discovered. This research proposes using a Raspberry Pi in conjunction with a Software Defined Radio to capture electromagnetic emanations in the low and high frequency domains. Two well-known side channel attacks will be used to recover the secret information based on the electromagnetic emanations. Furthermore, this research proposes investigating into a possible software countermeasure by using the high-powered devices features such as multi-threading.
- Full Text:
- Date Issued: 2016
- Authors: Frieslaar, Ibraheem , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427772 , vital:72461 , https://www.researchgate.net/profile/Ibraheem-Fries-laar/publication/312219190_Developing_a_Multi_Platform_Countermeasure_to_Ensure_a_Secure_Home/links/587747d508ae8fce492fb5e2/Developing-a-Multi-Platform-Countermeasure-to-Ensure-a-Secure-Home.pdf
- Description: This research proposes an investigation into the side channel analysis attacks against the AES algorithm on high powered devices. Currently the research field into this aspect is fairly new and there is room for more information to be discovered. This research proposes using a Raspberry Pi in conjunction with a Software Defined Radio to capture electromagnetic emanations in the low and high frequency domains. Two well-known side channel attacks will be used to recover the secret information based on the electromagnetic emanations. Furthermore, this research proposes investigating into a possible software countermeasure by using the high-powered devices features such as multi-threading.
- Full Text:
- Date Issued: 2016
Developing an attractant for monitoring fruit-feeding moths in citrus orchards
- Authors: Goddard, Mathew Keith
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2981 , vital:20349
- Description: Fruit-piercing moths are a sporadic pest of citrus, especially in the Eastern Cape Province of South Africa, where the adults can cause significant damage in outbreak years. Currently the only way in which to successfully control fruit-feeding moths within the orchards is the use of repellent lights. However, growers confuse fruit-piercing moths with fruit-sucking moths that don‘t cause primary damage, and there is no way of monitoring which moth species are attacking the fruit in the orchards during the night. In a previous study, banana was shown to be the most attractive bait for a variety of fruit-feeding moth species. Therefore the aim of this study was to determine the population dynamics of fruit-feeding moths develop a cost-effective alternative to the use of fresh banana as a bait for fruit-piercing moths. Fresh banana was compared to nine alternative synthetic attractants, frozen banana and a control under field conditions in several orchards in the Eastern Cape Province. Once again, banana was shown to be the most attractive bait. Some 23 species of fruit-feeding moth species were sampled in the traps, but there was only two fruit-piercing species, Serrodes partita (Fabricius) (Lepidoptera: Noctuidae) and Eudocima sp. Surprisingly S. partita, which was thought to be the main pest, comprised only 6.9% of trap catches. Serrodes partita, is a sporadic pest, only becoming problematic every five to 10 years after good rainfall in the Little Karoo region that causes flushes of their larval host, wild plum, Pappea capensis (Ecklon and Zeyher). During these outbreaks, damage to fruit can range from 70 to 90% and this is especially so for soft skinned citrus. A study on the morphology of the proboscis confirmed that only two species of fruit-piercing moths were present. Trap catches over three citrus growing seasons was linked to fruit damage found within several orchards. Once again fruit-piercing moth damage was relatively low in comparison to other types of damage such as mechanical and undefined damage. There was a very weak correlation between S. partita trap catches and damage, but generally damage was recorded two to three weeks after a peak in S. partita trap catches. Climatic conditions were also recorded and compared to weekly trap catches of S. partita, and while temperature and wind direction had no influence on moth populations, precipitation in the orchards was weakly correlated with trap catches. This study has shown that in non-outbreak seasons, the main fruit-piercing moth, S. partita comprises a small percentage of fruit-feeding moths in citrus orchards, but that growers are unable to determine the difference between fruit-piercing species and the harmless fruit-sucking species. Further fresh banana remains the best method for attracting fruit-piecing moths to traps, but this is not cost effective and thus a commercially viable protocol for monitoring these species remains elusive.
- Full Text:
- Date Issued: 2016
- Authors: Goddard, Mathew Keith
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2981 , vital:20349
- Description: Fruit-piercing moths are a sporadic pest of citrus, especially in the Eastern Cape Province of South Africa, where the adults can cause significant damage in outbreak years. Currently the only way in which to successfully control fruit-feeding moths within the orchards is the use of repellent lights. However, growers confuse fruit-piercing moths with fruit-sucking moths that don‘t cause primary damage, and there is no way of monitoring which moth species are attacking the fruit in the orchards during the night. In a previous study, banana was shown to be the most attractive bait for a variety of fruit-feeding moth species. Therefore the aim of this study was to determine the population dynamics of fruit-feeding moths develop a cost-effective alternative to the use of fresh banana as a bait for fruit-piercing moths. Fresh banana was compared to nine alternative synthetic attractants, frozen banana and a control under field conditions in several orchards in the Eastern Cape Province. Once again, banana was shown to be the most attractive bait. Some 23 species of fruit-feeding moth species were sampled in the traps, but there was only two fruit-piercing species, Serrodes partita (Fabricius) (Lepidoptera: Noctuidae) and Eudocima sp. Surprisingly S. partita, which was thought to be the main pest, comprised only 6.9% of trap catches. Serrodes partita, is a sporadic pest, only becoming problematic every five to 10 years after good rainfall in the Little Karoo region that causes flushes of their larval host, wild plum, Pappea capensis (Ecklon and Zeyher). During these outbreaks, damage to fruit can range from 70 to 90% and this is especially so for soft skinned citrus. A study on the morphology of the proboscis confirmed that only two species of fruit-piercing moths were present. Trap catches over three citrus growing seasons was linked to fruit damage found within several orchards. Once again fruit-piercing moth damage was relatively low in comparison to other types of damage such as mechanical and undefined damage. There was a very weak correlation between S. partita trap catches and damage, but generally damage was recorded two to three weeks after a peak in S. partita trap catches. Climatic conditions were also recorded and compared to weekly trap catches of S. partita, and while temperature and wind direction had no influence on moth populations, precipitation in the orchards was weakly correlated with trap catches. This study has shown that in non-outbreak seasons, the main fruit-piercing moth, S. partita comprises a small percentage of fruit-feeding moths in citrus orchards, but that growers are unable to determine the difference between fruit-piercing species and the harmless fruit-sucking species. Further fresh banana remains the best method for attracting fruit-piecing moths to traps, but this is not cost effective and thus a commercially viable protocol for monitoring these species remains elusive.
- Full Text:
- Date Issued: 2016
Developing biosensors in developing countries: South Africa as a case study
- Fogel, Ronen, Limson, Janice L
- Authors: Fogel, Ronen , Limson, Janice L
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431661 , vital:72794 , xlink:href="https://doi.org/10.3390/bios6010005"
- Description: A mini-review of the reported biosensor research occurring in South Africa evidences a strong emphasis on electrochemical sensor research, guided by the opportunities this transduction platform holds for low-cost and robust sensing of numerous targets. Many of the reported publications centre on fundamental research into the signal transduction method, using model biorecognition elements, in line with international trends. Other research in this field is spread across several areas including: the application of nanotechnology; the identification and validation of biomarkers; development and testing of biorecognition agents (antibodies and aptamers) and design of electro-catalysts, most notably metallophthalocyanine. Biosensor targets commonly featured were pesticides and metals. Areas of regional import to sub-Saharan Africa, such as HIV/AIDs and tuberculosis diagnosis, are also apparent in a review of the available literature. Irrespective of the targets, the challenge to the effective deployment of such sensors remains shaped by social and economic realities such that the requirements thereof are for low-cost and universally easy to operate devices for field settings. While it is difficult to disentangle the intertwined roles of national policy, grant funding availability and, certainly, of global trends in shaping areas of emphasis in research, most notable is the strong role that nanotechnology, and to a certain extent biotechnology, plays in research regarding biosensor construction. Stronger emphasis on collaboration between scientists in theoretical modelling, nanomaterials application and or relevant stakeholders in the specific field (e.g., food or health monitoring) and researchers in biosensor design may help evolve focused research efforts towards development and deployment of low-cost biosensors.
- Full Text:
- Date Issued: 2016
- Authors: Fogel, Ronen , Limson, Janice L
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431661 , vital:72794 , xlink:href="https://doi.org/10.3390/bios6010005"
- Description: A mini-review of the reported biosensor research occurring in South Africa evidences a strong emphasis on electrochemical sensor research, guided by the opportunities this transduction platform holds for low-cost and robust sensing of numerous targets. Many of the reported publications centre on fundamental research into the signal transduction method, using model biorecognition elements, in line with international trends. Other research in this field is spread across several areas including: the application of nanotechnology; the identification and validation of biomarkers; development and testing of biorecognition agents (antibodies and aptamers) and design of electro-catalysts, most notably metallophthalocyanine. Biosensor targets commonly featured were pesticides and metals. Areas of regional import to sub-Saharan Africa, such as HIV/AIDs and tuberculosis diagnosis, are also apparent in a review of the available literature. Irrespective of the targets, the challenge to the effective deployment of such sensors remains shaped by social and economic realities such that the requirements thereof are for low-cost and universally easy to operate devices for field settings. While it is difficult to disentangle the intertwined roles of national policy, grant funding availability and, certainly, of global trends in shaping areas of emphasis in research, most notable is the strong role that nanotechnology, and to a certain extent biotechnology, plays in research regarding biosensor construction. Stronger emphasis on collaboration between scientists in theoretical modelling, nanomaterials application and or relevant stakeholders in the specific field (e.g., food or health monitoring) and researchers in biosensor design may help evolve focused research efforts towards development and deployment of low-cost biosensors.
- Full Text:
- Date Issued: 2016
Development and assessment of a USP Apparatus 3 dissolution test method for sustained-release Nevirapine matrix tablets
- Mwila, Chiluba, Khamanga, Sandile M M, Walker, Roderick B
- Authors: Mwila, Chiluba , Khamanga, Sandile M M , Walker, Roderick B
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184779 , vital:44271 , xlink:href="https://doi.org/10.14227/dt230316p22"
- Description: Dissolution testing is a quality control tool used to assess batch-to-batch performance of dosage forms, thereby providing continued assurance of product quality. Analytical methods for the assessment of pharmaceutical product quality must be validated according to regulatory guidelines to ensure that tests are reliable and valid. Agitation rate, mesh pore size, surfactant concentration, and dissolution medium molarity are experimental parameters that may affect nevirapine (NVP) release and were investigated and optimized to ensure that consistent, reliable, and valid results using Apparatus 3 were produced. Agitation rate was investigated to establish an equivalent response to that observed for NVP release using Apparatus 2 at 50 rpm. A reciprocation rate of 5–10 dpm produced dissolution profiles that were similar to those observed using Apparatus 2. An increase in the molarity of the dissolution medium slightly increased the release rate of NVP, and a 50 mM buffer maintained at pH values mimicking gastrointestinal tract (GIT) conditions was selected for all experiments. With the addition of 2% sodium lauryl sulfate (SLS) to the dissolution medium, >80% NVP was released from the tablets over the test period. The NVP release rate increased with an increase in the mesh pore size; however, the extent of release was not affected by this parameter. Dissolution test samples were analyzed using HPLC, and dissolution methods were validated for NVP stability in the dissolution medium, specificity, linearity and range, repeatability, intermediate precision, and accuracy as defined by ICH. The dissolution method used for testing NVP tablets can be regarded as an appropriate tool for the evaluation of sustained-release (SR) NVP formulations and the impact of formulation composition and product quality attributes on drug release.
- Full Text:
- Date Issued: 2016
- Authors: Mwila, Chiluba , Khamanga, Sandile M M , Walker, Roderick B
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184779 , vital:44271 , xlink:href="https://doi.org/10.14227/dt230316p22"
- Description: Dissolution testing is a quality control tool used to assess batch-to-batch performance of dosage forms, thereby providing continued assurance of product quality. Analytical methods for the assessment of pharmaceutical product quality must be validated according to regulatory guidelines to ensure that tests are reliable and valid. Agitation rate, mesh pore size, surfactant concentration, and dissolution medium molarity are experimental parameters that may affect nevirapine (NVP) release and were investigated and optimized to ensure that consistent, reliable, and valid results using Apparatus 3 were produced. Agitation rate was investigated to establish an equivalent response to that observed for NVP release using Apparatus 2 at 50 rpm. A reciprocation rate of 5–10 dpm produced dissolution profiles that were similar to those observed using Apparatus 2. An increase in the molarity of the dissolution medium slightly increased the release rate of NVP, and a 50 mM buffer maintained at pH values mimicking gastrointestinal tract (GIT) conditions was selected for all experiments. With the addition of 2% sodium lauryl sulfate (SLS) to the dissolution medium, >80% NVP was released from the tablets over the test period. The NVP release rate increased with an increase in the mesh pore size; however, the extent of release was not affected by this parameter. Dissolution test samples were analyzed using HPLC, and dissolution methods were validated for NVP stability in the dissolution medium, specificity, linearity and range, repeatability, intermediate precision, and accuracy as defined by ICH. The dissolution method used for testing NVP tablets can be regarded as an appropriate tool for the evaluation of sustained-release (SR) NVP formulations and the impact of formulation composition and product quality attributes on drug release.
- Full Text:
- Date Issued: 2016
Development Discourse and Global History: From Colonialism to the Sustainable Development Goals. A book review
- Authors: Matthews, Sally
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142257 , vital:38063 , DOI: 10.1080/00220388.2016.1153185
- Description: Development Discourse and Global History: From Colonialism to the Sustainable Development Goals. A book review.
- Full Text:
- Date Issued: 2016
- Authors: Matthews, Sally
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142257 , vital:38063 , DOI: 10.1080/00220388.2016.1153185
- Description: Development Discourse and Global History: From Colonialism to the Sustainable Development Goals. A book review.
- Full Text:
- Date Issued: 2016
Development of a high-throughput bioassay to determine the rate of antimalarial drug action using fluorescent vitality probes
- Authors: Laming, Dustin
- Date: 2016
- Subjects: Malaria -- Africa , Plasmodium falciparum , Drug development , Fluorescence
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64434 , vital:28542
- Description: Malaria is one of the most prevalent diseases in Africa and the Plasmodium falciparum species is widely accepted as the most virulent, with a fatality rate of 15 – 20 % of reported cases of infection. While various treatments have been accepted into early stage clinical trials there has been little progress towards a proven vaccine. Pending a long term solution, endemic countries rely heavily on the development of innovative drugs with acute efficacy coupled with rapids mode of action. Until recently the rate of drug action has been measured by light microscopic examination of parasite morphology using blood slides of drug treated parasite cultures at regular time intervals. This technique is tedious and, most importantly, subject to interpretation with regards to distinguishing between viable and comprised parasite cells, thus making it impossible to objectively quantitate the rate of drug action. This study aimed to develop a series of bioassays using the calcein-acetoxymethyl and propidium iodide vitality probes which would allow the rate of drug action on Plasmodium falciparum malaria parasites to be assessed and ranked in relation to each other. A novel bioassay using these fluorescent vitality probes coupled with fluorescence microscopy was developed and optimized and allowed the rate of drug action on malaria parasites to be assessed i) rapidly (in relation to current assay techniques) and ii) in a semi-quantitative manner. Extrapolation to flow cytometry for improved quantification provided favourable rankings of drug killing rates in the pilot study, however, requires further development to increase throughput and approach the ultimate goal of producing a medium-throughput assay for rapidly assessing the rate of action of antimalarial drugs. Attempts to adapt the assay for use in a multiwell plate reader, as well as using ATP measurements as an indication of parasite vitality after drug treatment, was met with erratic results. The viability probes assay as it stands represents an improvement on other assay formats in terms of rapidity and quantification of live/compromised parasites in cultures.
- Full Text:
- Date Issued: 2016
- Authors: Laming, Dustin
- Date: 2016
- Subjects: Malaria -- Africa , Plasmodium falciparum , Drug development , Fluorescence
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64434 , vital:28542
- Description: Malaria is one of the most prevalent diseases in Africa and the Plasmodium falciparum species is widely accepted as the most virulent, with a fatality rate of 15 – 20 % of reported cases of infection. While various treatments have been accepted into early stage clinical trials there has been little progress towards a proven vaccine. Pending a long term solution, endemic countries rely heavily on the development of innovative drugs with acute efficacy coupled with rapids mode of action. Until recently the rate of drug action has been measured by light microscopic examination of parasite morphology using blood slides of drug treated parasite cultures at regular time intervals. This technique is tedious and, most importantly, subject to interpretation with regards to distinguishing between viable and comprised parasite cells, thus making it impossible to objectively quantitate the rate of drug action. This study aimed to develop a series of bioassays using the calcein-acetoxymethyl and propidium iodide vitality probes which would allow the rate of drug action on Plasmodium falciparum malaria parasites to be assessed and ranked in relation to each other. A novel bioassay using these fluorescent vitality probes coupled with fluorescence microscopy was developed and optimized and allowed the rate of drug action on malaria parasites to be assessed i) rapidly (in relation to current assay techniques) and ii) in a semi-quantitative manner. Extrapolation to flow cytometry for improved quantification provided favourable rankings of drug killing rates in the pilot study, however, requires further development to increase throughput and approach the ultimate goal of producing a medium-throughput assay for rapidly assessing the rate of action of antimalarial drugs. Attempts to adapt the assay for use in a multiwell plate reader, as well as using ATP measurements as an indication of parasite vitality after drug treatment, was met with erratic results. The viability probes assay as it stands represents an improvement on other assay formats in terms of rapidity and quantification of live/compromised parasites in cultures.
- Full Text:
- Date Issued: 2016
Development of a small production platform for citronellal processing
- Mafu, Lubabalo Rowan, Zeelie, Ben
- Authors: Mafu, Lubabalo Rowan , Zeelie, Ben
- Date: 2016
- Subjects: Organic compounds -- Synthesis , Plasticizers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8488 , vital:26370
- Description: The aim of the project was to develop a small production platform for citronellal processing. The objective of the study was to develop a single continuous flow reactor system for the synthesis of novel derivatives of citronellal and isopulegol. The first step was to develop a continuous flow reactor system for the isopulegol synthesis. The stainless steel tubular fixed-bed reactor equipped with a reaction column (I.D: 9.53 mm and length: 120 mm) was used for the study. The reactor column was packed with H-ZMS-5 zeolite extrusion catalyst. The solvent-free cyclisation reaction of citronellal was investigated and at optimum conditions, 100% of citronellal conversion and almost 100% selectivity towards isopulegol was achieved. A good catalytic performance was observed from the H-ZSM-5 catalyst and proved to be stable for a prolonged reaction time. The second reaction step was to develop a continuous flow reactor system for the synthesis of isopulegyl-ether derivatives. A UniQsis FlowSyn reactor system equipped with a stainless steel reactor column was used for the study. The reactor column was packed with amberlyst-15 dry catalyst. Wherein, n-propanol was employed as a model etherifying agent and as a reaction solvent. At optimum reaction condition, only 30% selectivity of isopulegyl propoxy-ether was achieved. The reaction was found to depend highly on temperature and residence time. The increase of these parameters was found to increase the side reactions and reduced the selectivity of the desired product. Other heterogeneous catalysts such as H-beta zeolite, aluminium pillared clay, Aluminium oxide and H-ZSM-5 were also evaluated in the reaction. Among these catalysts, a catalytic activity was observed with H-beta zeolite (19%) and aluminium pillared clay (5%). Based on these results, none of the evaluated catalysts provided the desired selectivity (greater than 70%) towards the isopulegyl propoxy-ether, therefore the process was not investigated further. In light of this, the isopulegol etherification synthetic route was terminated. Consequently, another analogue of citronellal was used as an alternative intermediate in place of isopulegol, namely para-menthane-3,8-diol (PMD). The initial studies for the synthesis of the novel PMD di-esters from isopulegol were performed in the batch-scale reactor. In a solvent-free reaction, acetic anhydride was initially used as a model acetylating agent. The reaction was performed using polymer-bound scandium triflate (PS-Sc(OTf)3) catalyst. The effect of reaction parameters such as temperature, molar ratio, and reaction time were studied towards the PMD conversion and di-esters selectivity. At optimum reaction conditions, PMD conversion of 70% and di-acetate selectivity of 67% were observed. The reaction was found to follow the zeroth-order kinetics with respect to PMD conversion and obeyed the Arrhenius equation. Other types of di-ester derivatives were synthesized from PMD by varying the carbon chain length of the acetylating agent. The prepared compounds were separated from the product mixtures by vacuum distillation, purified on a column chromatography and characterised by FT-IR, GC-MS, and 1H-NMR, 13C-NMR. The developed methodology was optimised in flow by using an ArrheniumOne microwave-assisted continuous-flow fixed-bed reactor system. A detailed experimental design was used to carry-out the reactions. The reaction parameters such as temperature and flow-rate were studied towards the PMD conversion and di-ester selectivity. From the experimental design analysis, the di-ester selectivity was found to depend highly on the residence time (flow-rate) and significantly on temperature. The PMD conversion and di-ester selectivity were found to increase with decrease in the flow-rate. The conversion and selectivity achieved in the continuous flow process were significantly higher than the achieved in the batch-scale process with respect to the residence time.
- Full Text:
- Date Issued: 2016
- Authors: Mafu, Lubabalo Rowan , Zeelie, Ben
- Date: 2016
- Subjects: Organic compounds -- Synthesis , Plasticizers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8488 , vital:26370
- Description: The aim of the project was to develop a small production platform for citronellal processing. The objective of the study was to develop a single continuous flow reactor system for the synthesis of novel derivatives of citronellal and isopulegol. The first step was to develop a continuous flow reactor system for the isopulegol synthesis. The stainless steel tubular fixed-bed reactor equipped with a reaction column (I.D: 9.53 mm and length: 120 mm) was used for the study. The reactor column was packed with H-ZMS-5 zeolite extrusion catalyst. The solvent-free cyclisation reaction of citronellal was investigated and at optimum conditions, 100% of citronellal conversion and almost 100% selectivity towards isopulegol was achieved. A good catalytic performance was observed from the H-ZSM-5 catalyst and proved to be stable for a prolonged reaction time. The second reaction step was to develop a continuous flow reactor system for the synthesis of isopulegyl-ether derivatives. A UniQsis FlowSyn reactor system equipped with a stainless steel reactor column was used for the study. The reactor column was packed with amberlyst-15 dry catalyst. Wherein, n-propanol was employed as a model etherifying agent and as a reaction solvent. At optimum reaction condition, only 30% selectivity of isopulegyl propoxy-ether was achieved. The reaction was found to depend highly on temperature and residence time. The increase of these parameters was found to increase the side reactions and reduced the selectivity of the desired product. Other heterogeneous catalysts such as H-beta zeolite, aluminium pillared clay, Aluminium oxide and H-ZSM-5 were also evaluated in the reaction. Among these catalysts, a catalytic activity was observed with H-beta zeolite (19%) and aluminium pillared clay (5%). Based on these results, none of the evaluated catalysts provided the desired selectivity (greater than 70%) towards the isopulegyl propoxy-ether, therefore the process was not investigated further. In light of this, the isopulegol etherification synthetic route was terminated. Consequently, another analogue of citronellal was used as an alternative intermediate in place of isopulegol, namely para-menthane-3,8-diol (PMD). The initial studies for the synthesis of the novel PMD di-esters from isopulegol were performed in the batch-scale reactor. In a solvent-free reaction, acetic anhydride was initially used as a model acetylating agent. The reaction was performed using polymer-bound scandium triflate (PS-Sc(OTf)3) catalyst. The effect of reaction parameters such as temperature, molar ratio, and reaction time were studied towards the PMD conversion and di-esters selectivity. At optimum reaction conditions, PMD conversion of 70% and di-acetate selectivity of 67% were observed. The reaction was found to follow the zeroth-order kinetics with respect to PMD conversion and obeyed the Arrhenius equation. Other types of di-ester derivatives were synthesized from PMD by varying the carbon chain length of the acetylating agent. The prepared compounds were separated from the product mixtures by vacuum distillation, purified on a column chromatography and characterised by FT-IR, GC-MS, and 1H-NMR, 13C-NMR. The developed methodology was optimised in flow by using an ArrheniumOne microwave-assisted continuous-flow fixed-bed reactor system. A detailed experimental design was used to carry-out the reactions. The reaction parameters such as temperature and flow-rate were studied towards the PMD conversion and di-ester selectivity. From the experimental design analysis, the di-ester selectivity was found to depend highly on the residence time (flow-rate) and significantly on temperature. The PMD conversion and di-ester selectivity were found to increase with decrease in the flow-rate. The conversion and selectivity achieved in the continuous flow process were significantly higher than the achieved in the batch-scale process with respect to the residence time.
- Full Text:
- Date Issued: 2016
Development of a stemmer for the isiXhosa language
- Authors: Nogwina, Mnoneleli
- Date: 2016
- Subjects: Computational linguistics Language and languages Xhosa language
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2611 , vital:27938
- Description: IsiXhosa language is one of the eleven official languages and the second most widely spoken language in South Africa. However, in terms of computational linguistics, the language did not get attention and natural language related work is almost non-existent. Document retrieval using unstructured queries requires some kind of language processing, and an efficient retrieval of documents can be achieved if we use a technique called stemming. The area that involves document storage and retrieval is called Information Retrieval (IR). Basically, IR systems make use of a Stemmer to index document representations and also terms in users’ queries to retrieve matching documents. In this dissertation, we present the developed Stemmer that can be used in both conditions. The Stemmer is used in IR systems, like Google to retrieve documents written in isiXhosa. In the Eastern Cape Province of South Africa many public schools take isiXhosa as a subject and also a number of Universities in South Africa teach isiXhosa. Therefore, for a language important such as this, it is important to make valuable information that is available online accessible to users through the use of IR systems. In our efforts to develop a Stemmer for the isiXhosa language, an investigation on how others have developed Stemmers for other languages was carried out. From the investigation we came to realize that the Porter stemming algorithm in particular was the main algorithm that many of other Stemmers make use of as a reference. We found that Porter’s algorithm could not be used in its totality in the development of the isiXhosa Stemmer because of the morphological complexity of the language. We developed an affix removal that is embedded with rules that determine which order should be followed in stripping the affixes. The rule is that, the word under consideration is checked against the exceptions, if it’s not in the exceptions list then the stripping continue in the following order; Prefix removal, Suffix removal and finally save the result as stem. The Stemmer was successfully developed and was tested and evaluated in a sample data that was randomly collected from the isiXhosa text books and isiXhosa dictionary. From the results obtained we concluded that the Stemmer can be used in IR systems as it showed 91 percent accuracy. The errors were 9 percent and therefore these results are within the accepted range and therefore the Stemmer can be used to help in retrieval of isiXhosa documents. This is only a noun Stemmer and in the future it can be extended to also stem verbs as well. The Stemmer can also be used in the development of spell-checkers of isiXhosa.
- Full Text:
- Date Issued: 2016
- Authors: Nogwina, Mnoneleli
- Date: 2016
- Subjects: Computational linguistics Language and languages Xhosa language
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2611 , vital:27938
- Description: IsiXhosa language is one of the eleven official languages and the second most widely spoken language in South Africa. However, in terms of computational linguistics, the language did not get attention and natural language related work is almost non-existent. Document retrieval using unstructured queries requires some kind of language processing, and an efficient retrieval of documents can be achieved if we use a technique called stemming. The area that involves document storage and retrieval is called Information Retrieval (IR). Basically, IR systems make use of a Stemmer to index document representations and also terms in users’ queries to retrieve matching documents. In this dissertation, we present the developed Stemmer that can be used in both conditions. The Stemmer is used in IR systems, like Google to retrieve documents written in isiXhosa. In the Eastern Cape Province of South Africa many public schools take isiXhosa as a subject and also a number of Universities in South Africa teach isiXhosa. Therefore, for a language important such as this, it is important to make valuable information that is available online accessible to users through the use of IR systems. In our efforts to develop a Stemmer for the isiXhosa language, an investigation on how others have developed Stemmers for other languages was carried out. From the investigation we came to realize that the Porter stemming algorithm in particular was the main algorithm that many of other Stemmers make use of as a reference. We found that Porter’s algorithm could not be used in its totality in the development of the isiXhosa Stemmer because of the morphological complexity of the language. We developed an affix removal that is embedded with rules that determine which order should be followed in stripping the affixes. The rule is that, the word under consideration is checked against the exceptions, if it’s not in the exceptions list then the stripping continue in the following order; Prefix removal, Suffix removal and finally save the result as stem. The Stemmer was successfully developed and was tested and evaluated in a sample data that was randomly collected from the isiXhosa text books and isiXhosa dictionary. From the results obtained we concluded that the Stemmer can be used in IR systems as it showed 91 percent accuracy. The errors were 9 percent and therefore these results are within the accepted range and therefore the Stemmer can be used to help in retrieval of isiXhosa documents. This is only a noun Stemmer and in the future it can be extended to also stem verbs as well. The Stemmer can also be used in the development of spell-checkers of isiXhosa.
- Full Text:
- Date Issued: 2016
Development of an enzyme-synergy based bioreactor system for the beneficiation of apple pomace lignocellulosic waste
- Authors: Abboo, Sagaran
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/315 , vital:19947
- Description: Due to the finite supply of non-renewable fossil fuels, agro-industrial wastes are identified as alternate, renewable sources for energy supply. Large amounts of fruit waste are generated in South Africa due to fruit juice and wine processing from apples, grapes and citrus fruit. Apple pomace is the solid residue that is left over after juice, cider and wine processing and constitutes between 25-30% of the total fruit. On a global scale millions of tonnes of apple pomace are produced; between 2006-2007 over 46 million tonnes were produced. In South Africa a total production of 244 469 tonnes were produced during the 2011- 2012 season. Initially, apple pomace was regarded as a waste by-product used for animal feed and compost in soil, however presently it is considered a source of dietary fiber and natural antioxidants like polyphenols. In addition, apple pomace has a high carbohydrate content and can be enzymatically hydrolysed to produce sugar monomers which, in turn, can be fermented by yeasts to produce bioethanol. The polyphenols present in apple pomace can be used for their health properties, and the bioethanol can be used as a replacement for fossil fuel. Apple pomace is lignocellulosic in nature and consists of hemicellulose, cellulose, lignin and pectin. A combination of enzymes such as cellulases, hemicellulases, pectinases and lignases are required to operate in synergy for the degradation of lignocellulosic biomass. This is due to the recalcitrant nature of lignocellulose. This study investigated the degradation of apple pomace using a combination of commercially obtained enzyme cocktails viz. Viscozyme L , Celluclast 1.5L and Novozyme 188. The commercial enzymes Viscozyme L and Celluclast 1.5L were added in a ratio of 1:1 (50%:50%). The final concentrations of the enzymes were 0.019 mg/ml each. Novozyme 188 was added to provide a final concentration of 0.0024 mg/ml. A novel cost effective 20L bioreactor was designed, constructed and implemented for the degradation of apple pomace to produce value added products. The hydrolysis of the apple pomace was performed initially in 1 L flasks (batch fed) and, once optimized, scaled up to a 20 L bioreactor in batch mode. The bioreactors were operated at room temperature (22 ± 2ºC) and in an unbuffered system. The sugars released were detected and quantified using an optimized validated HPLC method established in this study. The sugars released in the bioreactors were mainly glucose, galactose, arabinose, cellobiose and fructose. The polyphenols released in this study were gallic acid, catechin, epicatechin, chlorogenic acid, rutin and phloridzin, which have a number of health benefits. The simultaneous analyses of the polyphenols were performed using a newly developed and validated HPLC method established in this study. This method was developed to detect nine polyphenols simultaneously. The two HPLC methods developed and validated in this study for the analysis of sugars and polyphenols demonstrated good accuracy, precision, reproducibility, linearity, robustness and sensitivity. Both analytical methods were validated according to the International Convention on Harmonization (ICH). The HPLC parameters for sugar analysis were: refractive index (RI) as the detection mode, the stationary phase was a ligand-exchange sugar column (Shodex SP0810) and an aqueous mobile phase in isocratic mode was used. The HPLC method for polyphenols employed UV diode array detection (DAD) as the detection mode, a reverse phase column as the stationary phase and a mobile phase of consisting of 0.01 M phosphoric acid in water and 100% methanol using gradient elution mode. The highest concentrations of sugars released in the novel 20 L bioreactor with 20% apple pomace (w/v) substrate loading were as follow: glucose (6.5 mg/ml), followed by galactose (2.1 mg/ml), arabinose (1.4 mg/ml), cellobiose (0.7 mg/ml) and fructose (0.5 mg/ml). The amounts of polyphenols released at 20% (w/v) apple pomace substrate were epicatechin (0.01 mg/ml), catechin (0.002 mg/ml), rutin (0.03 mg/ml), chlorogenic acid (0.002 mg/ml) and gallic acid 0.01 (mg/ml). Two mathematical models were developed in this study for kinetic analysis of lignocellulose (apple pomace) hydrolysis in the novel 20 L bioreactor, using the experimental data generated by the above HPLC analyses. The first model, modelling with regression, defines the hydrolysis of the sugars glucose, galactose, cellobiose and arabinose produced in the novel 20 L bioreactor at 5%, 10%, 15% and 20% (w/v) substrate concentrations. The regression model describes the sugars produced in the 20 L bioreactor by minimizing the error of the sugars released by finding a value for K which minimises the function which computes the sum of squares of errors between the solution curves and the data points. The second, more complex, model developed in this study used a system of differential equations model (ODE). This model solved the system by using a numerical method, such as the Runge-Kutta method, then fitted the solution curves to the data. Both models simulated (and had the ability to predict) the production of sugars in the novel 20 L bioreactor for apple pomace hydrolysis. These two models also revealed the time at which the maximum amount of sugars were released, which revealed the optimum time to run the 20 L bioreactor in order to be more cost effective. The optimum time for maximum glucose (the main sugar used in fermentation for biofuel production) release was determined to be around 60 h. The ODE model, in addition, determined the rate at which the substrate became depleted, as well as the rate at which the enzymes became deactivated for the various substrate loadings in the 20 L bioreactor. A third model was developed to determine the optimal running cost of the bioreactor which incorporated the substrate loading and the amount of glucose (g/L) produced. The novel 20 L bioreactor constructed from cost effective materials demonstrated that agro-industrial waste can be converted to value-added products by lignocellolytic enzymes. The sugars released from apple pomace can be used in biofuel production and the polyphenols as food supplements and nutraceuticals for health benefits. This novel study contributes to agro-industrial waste beneficiation via fuel production. In addition, using agro-industrial waste for the generation of value added products (instead of mere disposal) will help prevent environmental pollution.
- Full Text:
- Date Issued: 2016
- Authors: Abboo, Sagaran
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/315 , vital:19947
- Description: Due to the finite supply of non-renewable fossil fuels, agro-industrial wastes are identified as alternate, renewable sources for energy supply. Large amounts of fruit waste are generated in South Africa due to fruit juice and wine processing from apples, grapes and citrus fruit. Apple pomace is the solid residue that is left over after juice, cider and wine processing and constitutes between 25-30% of the total fruit. On a global scale millions of tonnes of apple pomace are produced; between 2006-2007 over 46 million tonnes were produced. In South Africa a total production of 244 469 tonnes were produced during the 2011- 2012 season. Initially, apple pomace was regarded as a waste by-product used for animal feed and compost in soil, however presently it is considered a source of dietary fiber and natural antioxidants like polyphenols. In addition, apple pomace has a high carbohydrate content and can be enzymatically hydrolysed to produce sugar monomers which, in turn, can be fermented by yeasts to produce bioethanol. The polyphenols present in apple pomace can be used for their health properties, and the bioethanol can be used as a replacement for fossil fuel. Apple pomace is lignocellulosic in nature and consists of hemicellulose, cellulose, lignin and pectin. A combination of enzymes such as cellulases, hemicellulases, pectinases and lignases are required to operate in synergy for the degradation of lignocellulosic biomass. This is due to the recalcitrant nature of lignocellulose. This study investigated the degradation of apple pomace using a combination of commercially obtained enzyme cocktails viz. Viscozyme L , Celluclast 1.5L and Novozyme 188. The commercial enzymes Viscozyme L and Celluclast 1.5L were added in a ratio of 1:1 (50%:50%). The final concentrations of the enzymes were 0.019 mg/ml each. Novozyme 188 was added to provide a final concentration of 0.0024 mg/ml. A novel cost effective 20L bioreactor was designed, constructed and implemented for the degradation of apple pomace to produce value added products. The hydrolysis of the apple pomace was performed initially in 1 L flasks (batch fed) and, once optimized, scaled up to a 20 L bioreactor in batch mode. The bioreactors were operated at room temperature (22 ± 2ºC) and in an unbuffered system. The sugars released were detected and quantified using an optimized validated HPLC method established in this study. The sugars released in the bioreactors were mainly glucose, galactose, arabinose, cellobiose and fructose. The polyphenols released in this study were gallic acid, catechin, epicatechin, chlorogenic acid, rutin and phloridzin, which have a number of health benefits. The simultaneous analyses of the polyphenols were performed using a newly developed and validated HPLC method established in this study. This method was developed to detect nine polyphenols simultaneously. The two HPLC methods developed and validated in this study for the analysis of sugars and polyphenols demonstrated good accuracy, precision, reproducibility, linearity, robustness and sensitivity. Both analytical methods were validated according to the International Convention on Harmonization (ICH). The HPLC parameters for sugar analysis were: refractive index (RI) as the detection mode, the stationary phase was a ligand-exchange sugar column (Shodex SP0810) and an aqueous mobile phase in isocratic mode was used. The HPLC method for polyphenols employed UV diode array detection (DAD) as the detection mode, a reverse phase column as the stationary phase and a mobile phase of consisting of 0.01 M phosphoric acid in water and 100% methanol using gradient elution mode. The highest concentrations of sugars released in the novel 20 L bioreactor with 20% apple pomace (w/v) substrate loading were as follow: glucose (6.5 mg/ml), followed by galactose (2.1 mg/ml), arabinose (1.4 mg/ml), cellobiose (0.7 mg/ml) and fructose (0.5 mg/ml). The amounts of polyphenols released at 20% (w/v) apple pomace substrate were epicatechin (0.01 mg/ml), catechin (0.002 mg/ml), rutin (0.03 mg/ml), chlorogenic acid (0.002 mg/ml) and gallic acid 0.01 (mg/ml). Two mathematical models were developed in this study for kinetic analysis of lignocellulose (apple pomace) hydrolysis in the novel 20 L bioreactor, using the experimental data generated by the above HPLC analyses. The first model, modelling with regression, defines the hydrolysis of the sugars glucose, galactose, cellobiose and arabinose produced in the novel 20 L bioreactor at 5%, 10%, 15% and 20% (w/v) substrate concentrations. The regression model describes the sugars produced in the 20 L bioreactor by minimizing the error of the sugars released by finding a value for K which minimises the function which computes the sum of squares of errors between the solution curves and the data points. The second, more complex, model developed in this study used a system of differential equations model (ODE). This model solved the system by using a numerical method, such as the Runge-Kutta method, then fitted the solution curves to the data. Both models simulated (and had the ability to predict) the production of sugars in the novel 20 L bioreactor for apple pomace hydrolysis. These two models also revealed the time at which the maximum amount of sugars were released, which revealed the optimum time to run the 20 L bioreactor in order to be more cost effective. The optimum time for maximum glucose (the main sugar used in fermentation for biofuel production) release was determined to be around 60 h. The ODE model, in addition, determined the rate at which the substrate became depleted, as well as the rate at which the enzymes became deactivated for the various substrate loadings in the 20 L bioreactor. A third model was developed to determine the optimal running cost of the bioreactor which incorporated the substrate loading and the amount of glucose (g/L) produced. The novel 20 L bioreactor constructed from cost effective materials demonstrated that agro-industrial waste can be converted to value-added products by lignocellolytic enzymes. The sugars released from apple pomace can be used in biofuel production and the polyphenols as food supplements and nutraceuticals for health benefits. This novel study contributes to agro-industrial waste beneficiation via fuel production. In addition, using agro-industrial waste for the generation of value added products (instead of mere disposal) will help prevent environmental pollution.
- Full Text:
- Date Issued: 2016
Development of aptamers against epitopes of the Ebola virus nucleoprotein for future applications in diagnostics
- Mutombwera , Atherton Tiripano
- Authors: Mutombwera , Atherton Tiripano
- Date: 2016
- Subjects: Ebola virus disease Ebola virus disease -- Treatment , Epidemics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/45931 , vital:39321
- Description: Five different subtypes of the Ebola virus (EBOV) have been described. Either Zaire or Sudan EBOV subtypes has caused all of the EBOV outbreaks to date. The March 2014 Zaire EBOV disease outbreak that ravaged West Africa had a mortality rate of 70%, and resulted in 11 315 deaths. Swift cost effective EBOV detection is required to manage EBOV disease outbreaks as this leads to the interruption of the chain of transmission. Lateral flow diagnostic devices (LFDs) have been designed to provide quick, simple and cost effective diagnosis at the point of care and have great potential at interrupting the chain of EBOV transmission. The target recognition elements used in LFDs are the most important components of an LFD as they determine not only the selectivity and specificity of the device but also the transportation and storage conditions of the devices. Antibodies are the most common biomolecules used as target recognition elements in LFDs. However, the cost of producing antibodies is high and these biomolecules are highly sensitive to changes in the environmental conditions (e.g. temperature, pH and ionic strengths of buffer conditions), which can affect the selectivity and specificity of the LFDs. Aptamers can be used as alternative target recognition elements in LFDs. Aptamers are short single stranded nucleic acid molecules that have the ability to bind to their targets (e.g. whole cells, small molecules, toxins, proteins and peptides) with high affinity and specificity. By replacing antibodies with aptamers, LFDs can be produced that are less expensive, have higher selectivity and specificity. The aim of this study was to generate aptamers against the two highly conserved linear epitope regions (amino acid 421-440 and amino acid 601-620) of the EBOV nuclear protein (NP) using site directed SELEX. Such aptamers can be used as target recognition elements in the development of a LFD for the diagnosis of EBOV infection. Four aptamers that can potentially bind to the linear epitope spanning from amino acid 421 to 440 of the EBOV NP and four aptamers that can potentially bind to the linear epitope spanning from amino acid 601 to 620 of the EBOV NP were identified in this study. An in silico analysis of the predicted secondary structure of the putative aptamers was performed before and after the truncation of nucleotide sequences from the 5’ and 3’ ends of the aptamers to remove excess nucleotide sequences. Although this study did not characterise the interaction between the aptamers and linear epitope regions, the study succeeded in optimising the buffer conditions for future interaction studies using the SPR Biacore 3000 instrument.
- Full Text:
- Date Issued: 2016
- Authors: Mutombwera , Atherton Tiripano
- Date: 2016
- Subjects: Ebola virus disease Ebola virus disease -- Treatment , Epidemics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/45931 , vital:39321
- Description: Five different subtypes of the Ebola virus (EBOV) have been described. Either Zaire or Sudan EBOV subtypes has caused all of the EBOV outbreaks to date. The March 2014 Zaire EBOV disease outbreak that ravaged West Africa had a mortality rate of 70%, and resulted in 11 315 deaths. Swift cost effective EBOV detection is required to manage EBOV disease outbreaks as this leads to the interruption of the chain of transmission. Lateral flow diagnostic devices (LFDs) have been designed to provide quick, simple and cost effective diagnosis at the point of care and have great potential at interrupting the chain of EBOV transmission. The target recognition elements used in LFDs are the most important components of an LFD as they determine not only the selectivity and specificity of the device but also the transportation and storage conditions of the devices. Antibodies are the most common biomolecules used as target recognition elements in LFDs. However, the cost of producing antibodies is high and these biomolecules are highly sensitive to changes in the environmental conditions (e.g. temperature, pH and ionic strengths of buffer conditions), which can affect the selectivity and specificity of the LFDs. Aptamers can be used as alternative target recognition elements in LFDs. Aptamers are short single stranded nucleic acid molecules that have the ability to bind to their targets (e.g. whole cells, small molecules, toxins, proteins and peptides) with high affinity and specificity. By replacing antibodies with aptamers, LFDs can be produced that are less expensive, have higher selectivity and specificity. The aim of this study was to generate aptamers against the two highly conserved linear epitope regions (amino acid 421-440 and amino acid 601-620) of the EBOV nuclear protein (NP) using site directed SELEX. Such aptamers can be used as target recognition elements in the development of a LFD for the diagnosis of EBOV infection. Four aptamers that can potentially bind to the linear epitope spanning from amino acid 421 to 440 of the EBOV NP and four aptamers that can potentially bind to the linear epitope spanning from amino acid 601 to 620 of the EBOV NP were identified in this study. An in silico analysis of the predicted secondary structure of the putative aptamers was performed before and after the truncation of nucleotide sequences from the 5’ and 3’ ends of the aptamers to remove excess nucleotide sequences. Although this study did not characterise the interaction between the aptamers and linear epitope regions, the study succeeded in optimising the buffer conditions for future interaction studies using the SPR Biacore 3000 instrument.
- Full Text:
- Date Issued: 2016
Development of nanocomposites of phosphorus-nitrogen co-doped graphene oxide nanosheets and nanosized cobalt phthalocyanines for electrocatalysis
- Shumba, Munyaradzai, Nyokong, Tebello
- Authors: Shumba, Munyaradzai , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188574 , vital:44766 , xlink:href="https://doi.org/10.1016/j.electacta.2016.07.079"
- Description: Conjugates of reduced phosphorus-nitrogen co-doped graphene oxide nanosheets (rPNDGONS), reduced phosphorus doped graphene oxide nanosheets (rPDGONS), reduced nitrogen doped graphene oxide nanosheets (rNDGONS), reduced pyrolised graphene oxide nanosheets (rpyGONS) with nanosized cobalt (II) phthalocyanine (CoPcNP) or cobalt tetra amino phenoxy phthalocyanine (CoTAPhPcNP) were characterised and tested for their electrocatalytic behaviour towards the detection of hydrogen peroxide. Cyclic and linear scan voltammetries, and chronoamperometry were used to evaluate the electrocatalytic nature of the designed probes. For hydrogen peroxide detection, CoPcNP-rPNDGONS-GCE oxidation gave sensitivity of 12.00 mA/M, limit of detection of 4.48 nM, a rate constant of 2.66 × 105 M−1 s−1, adsorption equilibrium constant of 3.7 × 102 M−1 and Gibbs free energy −14.84 kJmol−1. The lowest detection limit was obtained for CoTAPhPcNP-rPNDGONS-GCE at 1.21 nM.
- Full Text:
- Date Issued: 2016
- Authors: Shumba, Munyaradzai , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188574 , vital:44766 , xlink:href="https://doi.org/10.1016/j.electacta.2016.07.079"
- Description: Conjugates of reduced phosphorus-nitrogen co-doped graphene oxide nanosheets (rPNDGONS), reduced phosphorus doped graphene oxide nanosheets (rPDGONS), reduced nitrogen doped graphene oxide nanosheets (rNDGONS), reduced pyrolised graphene oxide nanosheets (rpyGONS) with nanosized cobalt (II) phthalocyanine (CoPcNP) or cobalt tetra amino phenoxy phthalocyanine (CoTAPhPcNP) were characterised and tested for their electrocatalytic behaviour towards the detection of hydrogen peroxide. Cyclic and linear scan voltammetries, and chronoamperometry were used to evaluate the electrocatalytic nature of the designed probes. For hydrogen peroxide detection, CoPcNP-rPNDGONS-GCE oxidation gave sensitivity of 12.00 mA/M, limit of detection of 4.48 nM, a rate constant of 2.66 × 105 M−1 s−1, adsorption equilibrium constant of 3.7 × 102 M−1 and Gibbs free energy −14.84 kJmol−1. The lowest detection limit was obtained for CoTAPhPcNP-rPNDGONS-GCE at 1.21 nM.
- Full Text:
- Date Issued: 2016