Assessing the readiness for the implementation of municipal standard chart of accounts (mSCOA)
- Authors: Kwetana, Bulumko
- Date: 2019
- Subjects: Municipal finance -- South Africa , Municipal finance -- Accounting -- South Africa Accounting
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/40489 , vital:36170
- Description: The research project was undertaken to explore the readiness for the implementation of the municipal standard chart of accounts (mSCOA) in Eastern Cape municipalities. The Municipal Finance Management Act (MFMA) and other reporting guidelines emphasise on enhancing the quality of information to improve the relevance of financial reporting. They also make emphasis on the importance of preparing regular, accurate and complete financial and performance reports that are supported and evidenced by reliable information. In South Africa, the reporting system of the municipalities has been decentralised, and various municipalities use different financial reporting systems. The recently introduced mSCOA provides a uniform and standardised financial transaction classification framework. Essentially this means that mSCOA prescribes the method (the how) and format (the look) that municipalities and their entities should use to record and classify all expenditure (capital and operating), revenue, assets, liabilities, equity, policy outcomes and legislative reporting. The literature review explores the existing information for correlation with the implementation of mSCOA and recommendations are made to the National Treasury to ensure an approach and conversion plan that would be relevant and practical in the current municipal environment and address all challenges and concerns identified within a reasonable time frame. Overall, the municipalities were not ready for the overall mSCOA implementation as depicted by the challenges municipalities are facing. However, the results of the study showed that stakeholders play a huge role in facilitating the transition to mSCOA and can also create an enabling environment for change. Management should ensure more training mechanisms are in place to ensure all employees are well- versed with the management information systems that they use daily. Management should encourage enterprise risk management principles to be part of the culture of the municipalities on every project. The importance of the research for the public sector resides in recognition of the need for a better understanding of mSCOA as a wide public-sector reform so that significant risks and challenges related to mSCOA implementation are well anticipated.
- Full Text:
- Date Issued: 2019
- Authors: Kwetana, Bulumko
- Date: 2019
- Subjects: Municipal finance -- South Africa , Municipal finance -- Accounting -- South Africa Accounting
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/40489 , vital:36170
- Description: The research project was undertaken to explore the readiness for the implementation of the municipal standard chart of accounts (mSCOA) in Eastern Cape municipalities. The Municipal Finance Management Act (MFMA) and other reporting guidelines emphasise on enhancing the quality of information to improve the relevance of financial reporting. They also make emphasis on the importance of preparing regular, accurate and complete financial and performance reports that are supported and evidenced by reliable information. In South Africa, the reporting system of the municipalities has been decentralised, and various municipalities use different financial reporting systems. The recently introduced mSCOA provides a uniform and standardised financial transaction classification framework. Essentially this means that mSCOA prescribes the method (the how) and format (the look) that municipalities and their entities should use to record and classify all expenditure (capital and operating), revenue, assets, liabilities, equity, policy outcomes and legislative reporting. The literature review explores the existing information for correlation with the implementation of mSCOA and recommendations are made to the National Treasury to ensure an approach and conversion plan that would be relevant and practical in the current municipal environment and address all challenges and concerns identified within a reasonable time frame. Overall, the municipalities were not ready for the overall mSCOA implementation as depicted by the challenges municipalities are facing. However, the results of the study showed that stakeholders play a huge role in facilitating the transition to mSCOA and can also create an enabling environment for change. Management should ensure more training mechanisms are in place to ensure all employees are well- versed with the management information systems that they use daily. Management should encourage enterprise risk management principles to be part of the culture of the municipalities on every project. The importance of the research for the public sector resides in recognition of the need for a better understanding of mSCOA as a wide public-sector reform so that significant risks and challenges related to mSCOA implementation are well anticipated.
- Full Text:
- Date Issued: 2019
Assessing the use of private sector techniques and strategies in the public sector: the case of the department of provincial treasury & planning, Eastern Cape Province
- Authors: Cembi, Amanda Vuyo Obuhle
- Date: 2019
- Subjects: Finance, Public , Finance, Public -- Law and legislation -- South Africa -- Eastern Cape Financial management Public administration
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: http://hdl.handle.net/10948/37929 , vital:34264
- Description: The aim of this study was to determine and investigate the extent to which the Department of Treasury and Planning manage public finance making use of relevant private sector techniques and strategies. Financial management is a critical element of good governance and it requires a great deal of attention with parallel internal systems and controls. The study determines the role of various bodies within the public finance environment and the relevant legislative frameworks towards efficient and effective financial management by departments. The Public Finance Management Act(1999) and National Treasury Regulations (2009) require all government departments to ensure accountability on resource allocated to be able to measure value for money in relation to the delivery services to communities. The primary objective of this study was to assess the effectiveness and efficient management of public finance in terms of the PFMA as the legislative framework and the MTEF as a financial management tool. The Constitution Republic of South Africa (Act 108 of 1996) makes a provision that all the three government spheres to be developmental-oriented in nature with clear accountability and transparency lines towards service delivery. On the same breath, The Public Finance Management Act of 1999 (PFMA) is meant “To regulate financial management in the national government and provincial governments; to ensure that all revenue, expenditure, assets and liabilities of those governments are managed efficiently and effectively; to provide for the responsibilities of persons entrusted with financial management in those governments; and to provide for matters connected therewith”. With the above introductory contentions from different authors and researchers, this study will basically be on providing more details on the policy documents namely; PFMA so to establish the nature and extent to which effective and efficient financial management has improved good governance in the Department of Treasury & Planning, Eastern Cape Province.
- Full Text:
- Date Issued: 2019
- Authors: Cembi, Amanda Vuyo Obuhle
- Date: 2019
- Subjects: Finance, Public , Finance, Public -- Law and legislation -- South Africa -- Eastern Cape Financial management Public administration
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: http://hdl.handle.net/10948/37929 , vital:34264
- Description: The aim of this study was to determine and investigate the extent to which the Department of Treasury and Planning manage public finance making use of relevant private sector techniques and strategies. Financial management is a critical element of good governance and it requires a great deal of attention with parallel internal systems and controls. The study determines the role of various bodies within the public finance environment and the relevant legislative frameworks towards efficient and effective financial management by departments. The Public Finance Management Act(1999) and National Treasury Regulations (2009) require all government departments to ensure accountability on resource allocated to be able to measure value for money in relation to the delivery services to communities. The primary objective of this study was to assess the effectiveness and efficient management of public finance in terms of the PFMA as the legislative framework and the MTEF as a financial management tool. The Constitution Republic of South Africa (Act 108 of 1996) makes a provision that all the three government spheres to be developmental-oriented in nature with clear accountability and transparency lines towards service delivery. On the same breath, The Public Finance Management Act of 1999 (PFMA) is meant “To regulate financial management in the national government and provincial governments; to ensure that all revenue, expenditure, assets and liabilities of those governments are managed efficiently and effectively; to provide for the responsibilities of persons entrusted with financial management in those governments; and to provide for matters connected therewith”. With the above introductory contentions from different authors and researchers, this study will basically be on providing more details on the policy documents namely; PFMA so to establish the nature and extent to which effective and efficient financial management has improved good governance in the Department of Treasury & Planning, Eastern Cape Province.
- Full Text:
- Date Issued: 2019
Assessment of capacity building programmes offered to cooperatives in the Eastern Cape
- Authors: Salman, Lusanda
- Date: 2019
- Subjects: Cooperative societies -- South Africa -- Eastern Cape , Cooperative societies -- Economic aspects Economic development projects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/43523 , vital:36905
- Description: Cooperatives play an important role in delivering services to those in need within the communities. Capacity building efforts for cooperatives are very crucial in increasing their effectiveness and to redress problems associated with limited administrative and organisational capacity. By providing technical assistance, training, and grant funds, the functioning of the cooperatives is enhanced and ultimately the outcomes are improved. Despite consensus about the importance of capacity-building, little high-quality evidence exists on the impact of capacity-building investments. This research paper presents the findings from the assessment conducted on the impact of capacity- building initiatives offered to cooperatives. The participants of the study were cooperatives from the Eastern Cape, all eight district municipalities were represented and the study included stakeholders working with cooperatives that included various government departments, agencies and the private sector. Findings from the study provide clear evidence that capacity-building efforts increase the effectiveness of cooperatives to plan, organise and manage their organisations. It has emerged strongly from research that cooperatives that have received capacity-building support in any form, have improved in terms of their functioning compared to those that have never been capacitated before. However, cooperatives are still faced with many challenges specifically relating to operational challenges, which include administration, financial, and governance and weak capability in terms of the knowledge and skills they possess.
- Full Text:
- Date Issued: 2019
- Authors: Salman, Lusanda
- Date: 2019
- Subjects: Cooperative societies -- South Africa -- Eastern Cape , Cooperative societies -- Economic aspects Economic development projects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/43523 , vital:36905
- Description: Cooperatives play an important role in delivering services to those in need within the communities. Capacity building efforts for cooperatives are very crucial in increasing their effectiveness and to redress problems associated with limited administrative and organisational capacity. By providing technical assistance, training, and grant funds, the functioning of the cooperatives is enhanced and ultimately the outcomes are improved. Despite consensus about the importance of capacity-building, little high-quality evidence exists on the impact of capacity-building investments. This research paper presents the findings from the assessment conducted on the impact of capacity- building initiatives offered to cooperatives. The participants of the study were cooperatives from the Eastern Cape, all eight district municipalities were represented and the study included stakeholders working with cooperatives that included various government departments, agencies and the private sector. Findings from the study provide clear evidence that capacity-building efforts increase the effectiveness of cooperatives to plan, organise and manage their organisations. It has emerged strongly from research that cooperatives that have received capacity-building support in any form, have improved in terms of their functioning compared to those that have never been capacitated before. However, cooperatives are still faced with many challenges specifically relating to operational challenges, which include administration, financial, and governance and weak capability in terms of the knowledge and skills they possess.
- Full Text:
- Date Issued: 2019
Assessment of phytochemical constituents, antioxidant properties and cytotoxicity potentials of Leonutis leonurus and Boophone disticha extracts used in the management of Alzheimer’s disease in Hogsback, Eastern Cape, South Africa
- Authors: Tonisi, Sipho
- Date: 2019
- Subjects: Medicinal plants Alzheimer's disease
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: http://hdl.handle.net/10353/14726 , vital:40067
- Description: In this present study, the phytochemical compounds, antioxidant activities, and cytotoxicity potentials of solvent extracts (polar solvents) of Leonotis leonurus (L. leonurus) and Boophone disitcha (B. disticha) commonly used in the management of Alzheimer’s diseases in Hogsback, in the Eastern Cape, South Africa were investigated. The phytochemical compounds were determined by standard protocols of Folin–Ciocalteu method, aluminium chloride colorimetric method as well as Mayer’s and Wagner’s method. The antioxidant capabilities were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and nitric oxide radical scavenging assays. The majority of extracts from both plant species exhibited free radical scavenging potential for oxidants they were tested against viz; DPPH, hydrogen peroxide, ABTS and nitric oxide. They further displayed good reducing potential against ferric iron. The results have shown a concentration-dependent dose of inhibition/scavenging activity (in DPPH, hydrogen peroxide, ABTS and nitric oxide assays) and reducing ability (in ferric reducing assay). However, leaf extracts of L. leonurus displayed ineffective scavenging activity against nitric oxide whereas extracts from L. leonurus flower and B. disticha bulb had higher scavenging potential against the production of nitric oxide radical. The GC-MS profiles of the plants extracts revealed the presence of numerous bioactive compounds that are known to possess excellent anti-inflammatory and most importantly antioxidant properties. Another interesting observation of GC-MS analysis data was the presence of compounds reported to inhibit Acetycholinesterase (AChE), which is a key enzyme targeted in the treatment of Alzheimers’ Disease (AD). The cytotoxicy tests for these extracts were carried out in order to assess the potentential detrimental effects on human health using Alamar Blue assay. It was noted that an increase in the extract concentration of both plant species resulted in a noticeable decline in cell population. These extracts were then declared xix to be quite toxic against HeLa (human cervix adenocarcinoma cells) cells as the cell viability in some extracts was quite low. Hence, toxicity testing of the studied plants’ extracts against normal cells is highly imperative in the future study. The results from this present study scientifically validated the use of the studied plants in folkoric medicine for the management of Alzheimer’s diseases.
- Full Text:
- Date Issued: 2019
- Authors: Tonisi, Sipho
- Date: 2019
- Subjects: Medicinal plants Alzheimer's disease
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: http://hdl.handle.net/10353/14726 , vital:40067
- Description: In this present study, the phytochemical compounds, antioxidant activities, and cytotoxicity potentials of solvent extracts (polar solvents) of Leonotis leonurus (L. leonurus) and Boophone disitcha (B. disticha) commonly used in the management of Alzheimer’s diseases in Hogsback, in the Eastern Cape, South Africa were investigated. The phytochemical compounds were determined by standard protocols of Folin–Ciocalteu method, aluminium chloride colorimetric method as well as Mayer’s and Wagner’s method. The antioxidant capabilities were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and nitric oxide radical scavenging assays. The majority of extracts from both plant species exhibited free radical scavenging potential for oxidants they were tested against viz; DPPH, hydrogen peroxide, ABTS and nitric oxide. They further displayed good reducing potential against ferric iron. The results have shown a concentration-dependent dose of inhibition/scavenging activity (in DPPH, hydrogen peroxide, ABTS and nitric oxide assays) and reducing ability (in ferric reducing assay). However, leaf extracts of L. leonurus displayed ineffective scavenging activity against nitric oxide whereas extracts from L. leonurus flower and B. disticha bulb had higher scavenging potential against the production of nitric oxide radical. The GC-MS profiles of the plants extracts revealed the presence of numerous bioactive compounds that are known to possess excellent anti-inflammatory and most importantly antioxidant properties. Another interesting observation of GC-MS analysis data was the presence of compounds reported to inhibit Acetycholinesterase (AChE), which is a key enzyme targeted in the treatment of Alzheimers’ Disease (AD). The cytotoxicy tests for these extracts were carried out in order to assess the potentential detrimental effects on human health using Alamar Blue assay. It was noted that an increase in the extract concentration of both plant species resulted in a noticeable decline in cell population. These extracts were then declared xix to be quite toxic against HeLa (human cervix adenocarcinoma cells) cells as the cell viability in some extracts was quite low. Hence, toxicity testing of the studied plants’ extracts against normal cells is highly imperative in the future study. The results from this present study scientifically validated the use of the studied plants in folkoric medicine for the management of Alzheimer’s diseases.
- Full Text:
- Date Issued: 2019
Assessment of quality nursing care in healthcare facilities of Mnquma Sub-District
- Authors: Manyela, Nosiphiwo
- Date: 2019
- Subjects: Health facilities
- Language: English
- Type: Thesis , Masters , MPH
- Identifier: http://hdl.handle.net/10353/16747 , vital:40770
- Description: Aim: The purpose of the study was to assess the quality of patient care in the Primary Health Care (PHC) facilities of Mnquma Sub-district with the goal of improving or maintaining quality nursing in the area. Methodology: This study followed a quantitative research approach and it is descriptive in nature. The study involved 561 participants, of whom 406 participants were from urban clinics and 155 were from rural facilities, all these participants were attending clinics at Mnquma Sub-district. A structured questionnaire was used for data collection, since the participants were able to read and write in either English and or IsiXhosa. The data was analyzed with the help of a statistician using Statistical Package for Social Sciences (SPSS) program, software for windows version 21.0 Results: Results showed that participant’s responses to five of the twelve items on patient safety were found to have significant associations with residential setting. Rural participants were less likely to disagree with statements on availability of signage at the entrance of health establishment that indicates times when various services are offered, availability of the security guards to ensure patient safety, warning signs always put in place when the floors are wet, availability of at least one toilet for disabled patients in the health establishment and the fact that health professionals are always wearing name tags. This means that patient safety and security is practiced and implemented at the rural facilities according to the national core standards. The findings of the study confirmed that 13 items out of 19 under care and attitudes were found to have significant associations with residential setting. The items were patients spending less than 2 hours in the health facility; staff treating patients politely, illness being explained clearly to the patients, and ability of the patients to ask questions about their illness. Other items included nursing attitudes during opening and closing times of the health establishment, staff responding well when requested to assist, patients are being treated with empathy, patients are addressed by names and patients are being given all the treatment that they need, nurses explains the treatment side effects, and explains how to deal with side effects. This means that responses to these items depend on whether the patient is from a rural or urban clinic. Rural communities were found to be vi less likely to disagree with statements as compared to urban communities. This means that nurses are compliant with nursing care and attitudes in rural clinics. Findings of the study with respect to facility cleanliness, shows that there is no significant associations between the responses to the items which are: surroundings of the clinic are free of unpleasant smells, grounds of the clinic are clean, safe and clean grounds, bin waste inside and outside storage poses no health risks, and setting were detected. This means that the facilities are and cleanliness status remains the same across the residential settings. However, the younger age group was found be significantly more likely to disagree that toilets are clean and odorless and that grounds are safe and clean compared to the older age group. This suggests that the environment is clean except the toilets. Conclusion: Staffs at the facilities are at times ignorant and have negative attitudes at the opening and closing times and facilities have been reported to have long waiting times. The study indicated that the safety and security measures in the urban health facilities are not all practiced according to the National Core Standards checklist/Assessment tool, particularly wet warning signs, disabled toilets, and wearing of nametags. Majority of the participants indicated that, the status of cleanliness was on par at the urban and rural facilities.
- Full Text:
- Date Issued: 2019
- Authors: Manyela, Nosiphiwo
- Date: 2019
- Subjects: Health facilities
- Language: English
- Type: Thesis , Masters , MPH
- Identifier: http://hdl.handle.net/10353/16747 , vital:40770
- Description: Aim: The purpose of the study was to assess the quality of patient care in the Primary Health Care (PHC) facilities of Mnquma Sub-district with the goal of improving or maintaining quality nursing in the area. Methodology: This study followed a quantitative research approach and it is descriptive in nature. The study involved 561 participants, of whom 406 participants were from urban clinics and 155 were from rural facilities, all these participants were attending clinics at Mnquma Sub-district. A structured questionnaire was used for data collection, since the participants were able to read and write in either English and or IsiXhosa. The data was analyzed with the help of a statistician using Statistical Package for Social Sciences (SPSS) program, software for windows version 21.0 Results: Results showed that participant’s responses to five of the twelve items on patient safety were found to have significant associations with residential setting. Rural participants were less likely to disagree with statements on availability of signage at the entrance of health establishment that indicates times when various services are offered, availability of the security guards to ensure patient safety, warning signs always put in place when the floors are wet, availability of at least one toilet for disabled patients in the health establishment and the fact that health professionals are always wearing name tags. This means that patient safety and security is practiced and implemented at the rural facilities according to the national core standards. The findings of the study confirmed that 13 items out of 19 under care and attitudes were found to have significant associations with residential setting. The items were patients spending less than 2 hours in the health facility; staff treating patients politely, illness being explained clearly to the patients, and ability of the patients to ask questions about their illness. Other items included nursing attitudes during opening and closing times of the health establishment, staff responding well when requested to assist, patients are being treated with empathy, patients are addressed by names and patients are being given all the treatment that they need, nurses explains the treatment side effects, and explains how to deal with side effects. This means that responses to these items depend on whether the patient is from a rural or urban clinic. Rural communities were found to be vi less likely to disagree with statements as compared to urban communities. This means that nurses are compliant with nursing care and attitudes in rural clinics. Findings of the study with respect to facility cleanliness, shows that there is no significant associations between the responses to the items which are: surroundings of the clinic are free of unpleasant smells, grounds of the clinic are clean, safe and clean grounds, bin waste inside and outside storage poses no health risks, and setting were detected. This means that the facilities are and cleanliness status remains the same across the residential settings. However, the younger age group was found be significantly more likely to disagree that toilets are clean and odorless and that grounds are safe and clean compared to the older age group. This suggests that the environment is clean except the toilets. Conclusion: Staffs at the facilities are at times ignorant and have negative attitudes at the opening and closing times and facilities have been reported to have long waiting times. The study indicated that the safety and security measures in the urban health facilities are not all practiced according to the National Core Standards checklist/Assessment tool, particularly wet warning signs, disabled toilets, and wearing of nametags. Majority of the participants indicated that, the status of cleanliness was on par at the urban and rural facilities.
- Full Text:
- Date Issued: 2019
Assessment of some bacteria species isolated from woodlands of Raymond Mhlaba Local Municipality for high activity laccase production
- Authors: Gogotya, Asemahle
- Date: 2019
- Subjects: Laccase
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: http://hdl.handle.net/10353/19098 , vital:39879
- Description: The function of enzymes in keeping the earth clean is enormous; being executed in the biodegradation of different natural pollutants and biocatalysis of different responses by substituting the ecologically risky and harmful concoction impetuses offering a situation inviting option, laccases is an example of an enzyme described as it doesn’t produce harmful byproducts. Laccases are employed in several industrial processes that play a key responsibility in transformation of life and making the environment a better place. Bacteria have been described as best producers of laccases with a potential in the industrial scale processes. Laccase was produced from different bacterial isolates identified and named as Bacillus sp. strain GFN1 isolated from soil sample, Bacillus sp. strain GLN and Streptomyces sp. strain LAO both isolated from decaying wood samples in Raymond Mhlaba local municipality with accession numbers MK290988 to MK290990 respectively, as identified by partial sequencing, these were the best producers some of which were positive for Napthol and guaiacol; even upon quantitative screening they were better laccase producers. For quantitative laccase screening, 2,2'-azino-bis(3-ethylbenzothiazoline-6- sulphonic acid) was utilised as the substrate for laccase assays. These laccase producing bacteria were subjected to optimization of growth conditions using submerged fermentation which increased the activity of the produced laccase in great amounts. In optimizing basal medium growth conditions where laccase was harvested after every 72 hours where optimal activity was 16 obtained, studying several factors such as pH which turned out to be pH 5 for all isolates, effect of supplemented carbon and nitrogen sources with the be best being lactose and urea respectively with their effective concentrations using lignin as the main carbon and nitrogen source. Copper sulfate was used as the main inducer and the species preferred guaiacol and ferullic acid and the Fe2+ asthe best supplemented metal ion. The time course was done investigating parameters such as cell growth which was determined by observing the optical density, laccase activity, protein concentration and pH and the presented results suggested that when there was an increase in cell growth, enzyme activity decreased pH had no much effect on the enzyme production as it was almost stable all the time with protein concentration exhibiting no direct effect on enzyme activity also. Characterization of the crude enzyme was done to check the stability of the enzyme produced in various parameters. The enzymes produced by the different strains were thermophilic as they were able to withstand elevated temperatures between 90 and 100 C, with pH stability within an extensive variety of alkaline pH, typical of most bacterial laccases. Various metal ions affected the stability of the enzyme with CuSO4 increasing the stability of two of the bacterial enzyme and appeared to slightly decrease the stability of one enzyme. The studied inhibitors only decreased the stability on the enzyme and couldn’t completely inhibit the enzyme, and the enzymes showed specificity towards varying substrates. The studied bacterial laccases exhibit tremendous characteristics which are of great significance in the industries and will add to the novelty of bacterial laccases and their stability amongst the most studied fungal laccases.
- Full Text:
- Date Issued: 2019
- Authors: Gogotya, Asemahle
- Date: 2019
- Subjects: Laccase
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: http://hdl.handle.net/10353/19098 , vital:39879
- Description: The function of enzymes in keeping the earth clean is enormous; being executed in the biodegradation of different natural pollutants and biocatalysis of different responses by substituting the ecologically risky and harmful concoction impetuses offering a situation inviting option, laccases is an example of an enzyme described as it doesn’t produce harmful byproducts. Laccases are employed in several industrial processes that play a key responsibility in transformation of life and making the environment a better place. Bacteria have been described as best producers of laccases with a potential in the industrial scale processes. Laccase was produced from different bacterial isolates identified and named as Bacillus sp. strain GFN1 isolated from soil sample, Bacillus sp. strain GLN and Streptomyces sp. strain LAO both isolated from decaying wood samples in Raymond Mhlaba local municipality with accession numbers MK290988 to MK290990 respectively, as identified by partial sequencing, these were the best producers some of which were positive for Napthol and guaiacol; even upon quantitative screening they were better laccase producers. For quantitative laccase screening, 2,2'-azino-bis(3-ethylbenzothiazoline-6- sulphonic acid) was utilised as the substrate for laccase assays. These laccase producing bacteria were subjected to optimization of growth conditions using submerged fermentation which increased the activity of the produced laccase in great amounts. In optimizing basal medium growth conditions where laccase was harvested after every 72 hours where optimal activity was 16 obtained, studying several factors such as pH which turned out to be pH 5 for all isolates, effect of supplemented carbon and nitrogen sources with the be best being lactose and urea respectively with their effective concentrations using lignin as the main carbon and nitrogen source. Copper sulfate was used as the main inducer and the species preferred guaiacol and ferullic acid and the Fe2+ asthe best supplemented metal ion. The time course was done investigating parameters such as cell growth which was determined by observing the optical density, laccase activity, protein concentration and pH and the presented results suggested that when there was an increase in cell growth, enzyme activity decreased pH had no much effect on the enzyme production as it was almost stable all the time with protein concentration exhibiting no direct effect on enzyme activity also. Characterization of the crude enzyme was done to check the stability of the enzyme produced in various parameters. The enzymes produced by the different strains were thermophilic as they were able to withstand elevated temperatures between 90 and 100 C, with pH stability within an extensive variety of alkaline pH, typical of most bacterial laccases. Various metal ions affected the stability of the enzyme with CuSO4 increasing the stability of two of the bacterial enzyme and appeared to slightly decrease the stability of one enzyme. The studied inhibitors only decreased the stability on the enzyme and couldn’t completely inhibit the enzyme, and the enzymes showed specificity towards varying substrates. The studied bacterial laccases exhibit tremendous characteristics which are of great significance in the industries and will add to the novelty of bacterial laccases and their stability amongst the most studied fungal laccases.
- Full Text:
- Date Issued: 2019
Attitudes of healthcare professionals towards substance dependent Clients who have relapsed
- Authors: Yokwe, Zintle
- Date: 2019
- Subjects: Substance abuse -- Relapse , Substance abuse -- Psychological aspects Attitude (Psychology) Psychologists -- South Africa -- Attitudes
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/44345 , vital:37156
- Description: Relapse has been identified as a major problem when it comes to substancedependence. Research focusing on substance-dependence has found that substance users are at risk of relapsing after attending treatment, whether receiving out-patient or in-patient services. Healthcare professionals are seen as playing a crucial role when it comes to assisting substance-dependence clients; hence their attitudes when working with these clients are considered important. This study explored the attitudes of healthcare professionals when it came to working with substance-dependent clients who had relapsed. The study further explored whether the attitudes held by the healthcare professionals affected the treatment interventions or plans implemented. The study adopted the theory of planned behavior as a theoretical framework, and a qualitative research methodology was used. Nine participants (four social workers, one nurse, one drug counsellor, one psychologist and one registered counsellor) made up the research sample. A combination of convenience and purposive sampling techniques was used. Data was transcribed verbatim and analysed using thematic analysis. The findings of the study indicated that healthcare professionals displayed both positive and negatives attitudes when working with substance-dependent clients who had relapsed. The findings of the study showed that although some of the healthcare professionals displayed negative attitudes when clients relapsed, they still believed that their clients could recover and were committed to assisting them. The findings showed that healthcare professionals who worked with substance-dependent clients who had relapsed were influenced by the confidence they had in working with substance-dependence clients, their experiences, the client’s attitudes and level of motivation, as well as the client’s reasons for relapsing. This study also described the different treatment interventions healthcare professionals implemented when working with relapsed clients. Based on the conclusions made, it is important for healthcare professionals to have the relevant education, knowledge and experience that is needed to work with substance-dependence and relapse. The importance of healthcare professionals’ awareness of their attitudes and how these affect their behavior when working with substance-dependence was noted. It is recommend that similar studies are conducted in provinces or cities that have been identified to have high levels of substance-dependence relapse. Identifying healthcare professionals’ attitudes from these regions could result in more knowledge.
- Full Text:
- Date Issued: 2019
- Authors: Yokwe, Zintle
- Date: 2019
- Subjects: Substance abuse -- Relapse , Substance abuse -- Psychological aspects Attitude (Psychology) Psychologists -- South Africa -- Attitudes
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/44345 , vital:37156
- Description: Relapse has been identified as a major problem when it comes to substancedependence. Research focusing on substance-dependence has found that substance users are at risk of relapsing after attending treatment, whether receiving out-patient or in-patient services. Healthcare professionals are seen as playing a crucial role when it comes to assisting substance-dependence clients; hence their attitudes when working with these clients are considered important. This study explored the attitudes of healthcare professionals when it came to working with substance-dependent clients who had relapsed. The study further explored whether the attitudes held by the healthcare professionals affected the treatment interventions or plans implemented. The study adopted the theory of planned behavior as a theoretical framework, and a qualitative research methodology was used. Nine participants (four social workers, one nurse, one drug counsellor, one psychologist and one registered counsellor) made up the research sample. A combination of convenience and purposive sampling techniques was used. Data was transcribed verbatim and analysed using thematic analysis. The findings of the study indicated that healthcare professionals displayed both positive and negatives attitudes when working with substance-dependent clients who had relapsed. The findings of the study showed that although some of the healthcare professionals displayed negative attitudes when clients relapsed, they still believed that their clients could recover and were committed to assisting them. The findings showed that healthcare professionals who worked with substance-dependent clients who had relapsed were influenced by the confidence they had in working with substance-dependence clients, their experiences, the client’s attitudes and level of motivation, as well as the client’s reasons for relapsing. This study also described the different treatment interventions healthcare professionals implemented when working with relapsed clients. Based on the conclusions made, it is important for healthcare professionals to have the relevant education, knowledge and experience that is needed to work with substance-dependence and relapse. The importance of healthcare professionals’ awareness of their attitudes and how these affect their behavior when working with substance-dependence was noted. It is recommend that similar studies are conducted in provinces or cities that have been identified to have high levels of substance-dependence relapse. Identifying healthcare professionals’ attitudes from these regions could result in more knowledge.
- Full Text:
- Date Issued: 2019
Augmentative releases of Dactylopius austrinus De Lotto (Dactylopiidae; Hemiptera) for biological control of Opuntia aurantiaca Lindley (Cactaceae), in South Africa
- Authors: Mulateli, Thifhelimbilu
- Date: 2019
- Subjects: Opuntia aurantiaca -- Biolotical control -- South Africa , Invasive plants -- Biolotical control -- South Africa , Dactylopius austrinus De Lotto -- South Africa , Dactylopius -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92931 , vital:30765
- Description: Opuntia aurantiaca Lindely (Cactaceae) is an invasive alien cactus which has detrimental effects on agroecosystems and indigenous biodiversity in South Africa. Dense infestations over large areas reduce grazing capacity and indigenous biodiversity. Despite the release of a biological control agent, the cochineal insect Dactylopius austrinus De Lotto (Dactylopiidae), the weed is still considered a major problem in many parts of the country. Biological control has relied heavily on classical biological control, with little augmentative biological control implemented. This study investigated the outcome of mass-rearing and augmentative releases of D. austrinus for the control of O. aurantiaca. Augmentative releases are thought to improve the level of control by increasing agent densities in the field and thus increasing the level of damage inflicted to the plants. All data were collected with the intention to optimize release strategies so that the maximum benefit from the biological control agent could be achieved. An impact study was conducted using potted plants in a greenhouse to quantify the efficacy of multiple releases of the agent on the target weed. All three of the release treatments showed consistently higher proportion of cochineal than the controls, as well as the insect exclusion treatments, and these differences were statistically significant. The number of cladodes per plant increased significantly for the insect exclusion and control treatment over the period of the study, whilst all three release treatments decreased steadily over the same period. This study indicated that the agent is damaging to O. aurantiaca and that a single release event was beneficial but that multiple releases did not result in greater levels of control. A post-release evaluation was carried out to quantify the impact of releases of D. austrinus on O. aurantiaca in the field. Plots where the agent was excluded were compared with those where the agent was left at natural field densities and three treatments where agent populations were augmented to varying degrees through releases. The percentage of cochineal infested cladodes for all treatments decreased over time from the initiation of the experiment in October 2017 until the end of the experiment in October 2018. Opuntia aurantiaca densities also decreased over time for all treatments. The insect exclusion treatment had the greatest number of plants for the duration of the study, but this was not significantly different from other treatments. Dactylopius austrinus was damaging to O. aurantiaca, but climatic conditions in the field limited the efficacy of releases. Although O. aurantiaca density decreased during the experiment, it was evident that the reduced number of plants was not due to augmentation of the cochineal populations from the releases that were conducted. The experiment was conducted over a very dry period, when cochineal was particularly effective, so although augmentative releases did not improve the level of control, the natural population of cochineal was high and very damaging to O. aurantiaca over the course of the experiment. Releasing during wet periods, when the agent is less effective, could augment agent populations at a time when natural populations would be low, and hence improve levels of control further. Although this study was limited to a short period of two years, the results of this study suggest that the number of releases is less important than the timing of releases. Releasing immediately after periods of high rainfall is likely to be beneficial, while releasing during dry periods, or during winter when temperatures are low, is less effective. Dactylopius austrinus populations should be constantly monitored so that releases can be conducted when cochineal populations are low and the climatic conditions are correct. If the timing of release events is appropriate, then the over level of control of O. aurantiaca using D. austrinus could be improved.
- Full Text:
- Date Issued: 2019
- Authors: Mulateli, Thifhelimbilu
- Date: 2019
- Subjects: Opuntia aurantiaca -- Biolotical control -- South Africa , Invasive plants -- Biolotical control -- South Africa , Dactylopius austrinus De Lotto -- South Africa , Dactylopius -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92931 , vital:30765
- Description: Opuntia aurantiaca Lindely (Cactaceae) is an invasive alien cactus which has detrimental effects on agroecosystems and indigenous biodiversity in South Africa. Dense infestations over large areas reduce grazing capacity and indigenous biodiversity. Despite the release of a biological control agent, the cochineal insect Dactylopius austrinus De Lotto (Dactylopiidae), the weed is still considered a major problem in many parts of the country. Biological control has relied heavily on classical biological control, with little augmentative biological control implemented. This study investigated the outcome of mass-rearing and augmentative releases of D. austrinus for the control of O. aurantiaca. Augmentative releases are thought to improve the level of control by increasing agent densities in the field and thus increasing the level of damage inflicted to the plants. All data were collected with the intention to optimize release strategies so that the maximum benefit from the biological control agent could be achieved. An impact study was conducted using potted plants in a greenhouse to quantify the efficacy of multiple releases of the agent on the target weed. All three of the release treatments showed consistently higher proportion of cochineal than the controls, as well as the insect exclusion treatments, and these differences were statistically significant. The number of cladodes per plant increased significantly for the insect exclusion and control treatment over the period of the study, whilst all three release treatments decreased steadily over the same period. This study indicated that the agent is damaging to O. aurantiaca and that a single release event was beneficial but that multiple releases did not result in greater levels of control. A post-release evaluation was carried out to quantify the impact of releases of D. austrinus on O. aurantiaca in the field. Plots where the agent was excluded were compared with those where the agent was left at natural field densities and three treatments where agent populations were augmented to varying degrees through releases. The percentage of cochineal infested cladodes for all treatments decreased over time from the initiation of the experiment in October 2017 until the end of the experiment in October 2018. Opuntia aurantiaca densities also decreased over time for all treatments. The insect exclusion treatment had the greatest number of plants for the duration of the study, but this was not significantly different from other treatments. Dactylopius austrinus was damaging to O. aurantiaca, but climatic conditions in the field limited the efficacy of releases. Although O. aurantiaca density decreased during the experiment, it was evident that the reduced number of plants was not due to augmentation of the cochineal populations from the releases that were conducted. The experiment was conducted over a very dry period, when cochineal was particularly effective, so although augmentative releases did not improve the level of control, the natural population of cochineal was high and very damaging to O. aurantiaca over the course of the experiment. Releasing during wet periods, when the agent is less effective, could augment agent populations at a time when natural populations would be low, and hence improve levels of control further. Although this study was limited to a short period of two years, the results of this study suggest that the number of releases is less important than the timing of releases. Releasing immediately after periods of high rainfall is likely to be beneficial, while releasing during dry periods, or during winter when temperatures are low, is less effective. Dactylopius austrinus populations should be constantly monitored so that releases can be conducted when cochineal populations are low and the climatic conditions are correct. If the timing of release events is appropriate, then the over level of control of O. aurantiaca using D. austrinus could be improved.
- Full Text:
- Date Issued: 2019
Automatic termination clauses in employment contracts
- Authors: Ndzendze, Kutala
- Date: 2019
- Subjects: Labor contract -- South Africa , Employees -- Dismissal of -- Law and legislation -- South Africa Unfair labor practices -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/41808 , vital:36594
- Description: This study aims to establish Automatic Termination Clauses in Employment contracts by analyzing the provisions of the Constitution of the Republic of South Africa, Labour Relations Act and the precedents. The automatic termination of employment contract means that the contract is terminated without giving an employee the opportunity to state his or her version as per the audi alteram partem principle. In essence, the employee is deprived of his or her right to a fair dismissal as outlined in the Labour Relations Act. The automatic termination clauses in employment contract means that the employment contract will come to an end when the employee’s services are no longer required or when the employer simply does no longer want to keep the employee at work. The Constitution of the Republic of South Africa provides that “everyone has the right to fair labour practices”.1 In terms of the Labour Relations Act (hereinafter referred to as “the LRA”),2 every employee has the right not to be unfairly dismissed. An employment contract between an employee and employer arises out of a contract to perform services. This is so whether the contract is in writing or not. Dismissal is defined in the LRA3 as where the employer has terminated employment with or without a notice. The thesis is composed of five chapters, each of them dealing with different aspects of automatic termination clauses in employment contracts.
- Full Text:
- Date Issued: 2019
- Authors: Ndzendze, Kutala
- Date: 2019
- Subjects: Labor contract -- South Africa , Employees -- Dismissal of -- Law and legislation -- South Africa Unfair labor practices -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/41808 , vital:36594
- Description: This study aims to establish Automatic Termination Clauses in Employment contracts by analyzing the provisions of the Constitution of the Republic of South Africa, Labour Relations Act and the precedents. The automatic termination of employment contract means that the contract is terminated without giving an employee the opportunity to state his or her version as per the audi alteram partem principle. In essence, the employee is deprived of his or her right to a fair dismissal as outlined in the Labour Relations Act. The automatic termination clauses in employment contract means that the employment contract will come to an end when the employee’s services are no longer required or when the employer simply does no longer want to keep the employee at work. The Constitution of the Republic of South Africa provides that “everyone has the right to fair labour practices”.1 In terms of the Labour Relations Act (hereinafter referred to as “the LRA”),2 every employee has the right not to be unfairly dismissed. An employment contract between an employee and employer arises out of a contract to perform services. This is so whether the contract is in writing or not. Dismissal is defined in the LRA3 as where the employer has terminated employment with or without a notice. The thesis is composed of five chapters, each of them dealing with different aspects of automatic termination clauses in employment contracts.
- Full Text:
- Date Issued: 2019
Avoiding business failure in south africa
- Authors: Court, Nadine viargaret
- Date: 2019
- Subjects: Business failures -- Prevention -- South Africa , Business failures Success in business Business enterprises -- Management -- South Africa Small business -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/38024 , vital:34284
- Description: The purpose of this study was to develop a comprehensive framework to forecast that a business is entering a distressed situation and to identify the warning signs to look out for before it is too late to turn the business around in order to maintain a sustainable future. The possible solution lies in what business owners and management can do, and look out for, to avoid business failure. The intended contribution of the study was to design a framework for most businesses, especially SMMEs, to follow to avoid business failure. Therefore, it can be seen from this study that it is critical for business owners and management to be innovative in their business to achieve competitive advantage and, as such, remain sustainable. Stakeholder relationships are critical to achieving a competitive advantage. Financial Analysis, Technology Management, Innovation, Organisational Design and Risk Management are interrelated and are very inter-dependent when seeking to avoid business failure. However, innovation and technology management have a significant influence on business failure and, as such, are critical to the success of the business.
- Full Text:
- Date Issued: 2019
- Authors: Court, Nadine viargaret
- Date: 2019
- Subjects: Business failures -- Prevention -- South Africa , Business failures Success in business Business enterprises -- Management -- South Africa Small business -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/38024 , vital:34284
- Description: The purpose of this study was to develop a comprehensive framework to forecast that a business is entering a distressed situation and to identify the warning signs to look out for before it is too late to turn the business around in order to maintain a sustainable future. The possible solution lies in what business owners and management can do, and look out for, to avoid business failure. The intended contribution of the study was to design a framework for most businesses, especially SMMEs, to follow to avoid business failure. Therefore, it can be seen from this study that it is critical for business owners and management to be innovative in their business to achieve competitive advantage and, as such, remain sustainable. Stakeholder relationships are critical to achieving a competitive advantage. Financial Analysis, Technology Management, Innovation, Organisational Design and Risk Management are interrelated and are very inter-dependent when seeking to avoid business failure. However, innovation and technology management have a significant influence on business failure and, as such, are critical to the success of the business.
- Full Text:
- Date Issued: 2019
Benefits and limitation of informal trading in promoting sustainable local economic development in the Intsika Yethu Municipality
- Authors: Makubalo, Zukiswa
- Date: 2019
- Subjects: Municipal government -- South Africa -- Eastern Cape Sustainable development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: http://hdl.handle.net/10353/12425 , vital:39262
- Description: The informal sector refers to all economic activities by workers and economic units that are not covered or insufficiently covered by formal arrangements which can be carried out across all the sectors of the economy both in public and private spaces. The study was conducted to determine the benefits and limitation of informal trading in promoting sustainable local economic development in the Intsika Yethu Municipality. South African municipalities for various reasons fail in providing local economic development friendly environment and more developmental and inclusive informal economy policies and by-laws. The objective of the study was to assess the benefits and challenges which might hinder the maximisation of benefits in the sector. The literature was reviewed with the aim to integrate published academic data on the benefits and limitations of informal trading in promoting sustainable local economic development. Data for the study was sourced from the literature and questionnaires administered to respondents who were selected by means of a purposive sampling technique. The respondents from which data was collected were 18 and a qualitative research approach was used as a main research methodology. The responses obtained were subjected to content analyses. The main findings of the study include; informal traders are uncoordinated, informal traders are faced with challenges which hinder their success, majority of respondents see benefits from informal trading, the informal sector of responds to triple social ills and all respondents started up businesses due to the inability of the formal sector to create job opportunities that are permanent and enough for everyone. In response to the findings about the main recommendation made is the improvement of communication between government and informal trader for the sustainability of municipal programs.
- Full Text:
- Date Issued: 2019
- Authors: Makubalo, Zukiswa
- Date: 2019
- Subjects: Municipal government -- South Africa -- Eastern Cape Sustainable development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: http://hdl.handle.net/10353/12425 , vital:39262
- Description: The informal sector refers to all economic activities by workers and economic units that are not covered or insufficiently covered by formal arrangements which can be carried out across all the sectors of the economy both in public and private spaces. The study was conducted to determine the benefits and limitation of informal trading in promoting sustainable local economic development in the Intsika Yethu Municipality. South African municipalities for various reasons fail in providing local economic development friendly environment and more developmental and inclusive informal economy policies and by-laws. The objective of the study was to assess the benefits and challenges which might hinder the maximisation of benefits in the sector. The literature was reviewed with the aim to integrate published academic data on the benefits and limitations of informal trading in promoting sustainable local economic development. Data for the study was sourced from the literature and questionnaires administered to respondents who were selected by means of a purposive sampling technique. The respondents from which data was collected were 18 and a qualitative research approach was used as a main research methodology. The responses obtained were subjected to content analyses. The main findings of the study include; informal traders are uncoordinated, informal traders are faced with challenges which hinder their success, majority of respondents see benefits from informal trading, the informal sector of responds to triple social ills and all respondents started up businesses due to the inability of the formal sector to create job opportunities that are permanent and enough for everyone. In response to the findings about the main recommendation made is the improvement of communication between government and informal trader for the sustainability of municipal programs.
- Full Text:
- Date Issued: 2019
Between drones and al-Shabaab: United States extra-judicial killings in Somalia, sovereignty and the future of liberal intervention
- Authors: Koloko, Mojalefa
- Date: 2019
- Subjects: Somalia -- Politics and government -- 1991- , Somalia -- History -- 1991- , Somalia -- Foreign relations -- United States , Somalia -- Foreign relations -- 1991- , Military assistance, American -- Somalia , Extrajudicial exeutions -- Somalia , Shabaab (Organization)
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/67657 , vital:29125
- Description: This study examines the nature of the United States intervention in Somalia, specifically the use of drone strikes that first targeted the militant Sunni Islamist transnational group, al-Qaeda, which claimed responsibility for the 11 September 2001 attacks on the United States, and now target the Somali organisation, Harakat al-Shabaab al-Mujahidin, commonly known as al-Shabaab. The use of drone strikes in the US led war on terror has raised concerns about sovereignty as the extra-judicial killings are conducted without the consent of the concerned states. Furthermore, drone strikes also raise questions about the processes of liberal intervention as the US conducts them without the approval of the United Nations Security Council. It is argued in this study that what is understood to be the “golden era” of liberal interventionism is a legacy of the post-Cold War unipolar dominance of the United States in global governance and security. It is argued that US unipolarity was accompanied by a shifting perception regarding the security position of weak states, whose weakness becomes understood as a source of global insecurity. This perception that so called “weak” and “fragile” states are sources of threats is a departure in International Relations theory, because the discipline is historically preoccupied with studying the actions of powerful states and their consequence for the global order. It is argued that the discourse on the war on terror, and its focus on “failed states” as breeding grounds for alleged terrorists, represents the height of the repositioning of less powerful states from a peripheral status in IR analysis and practice, to their current position that are now being represented as core sources of threat to international peace and security. Through life history interviews with Somali nationals in Grahamstown, Port Elizabeth and Uitenhage, South Africa, the study examines the consequences of US actions from the eyes of Somali people. The findings of this study show that despite all the controversy surrounding the legitimacy of the war on terror, the manner in which it is conducted, as well as the tactics that it employs, the majority of Somali participants showed an overwhelming support for the US intervention. Participants expressed support for the US extra-judicial killings because they are understood to undermine al-Shabaab strength which is a major source of insecurity. The study also shows that the lack of necessary collaboration between the US intelligence and the Somali ground forces has resulted in high numbers of civilian deaths, which participants fear can be used by al-Shabaab to recruit and radicalise more Somalis. The study also shows that most Somalis resent the presence of the African Union Mission in Somalia because Kenya and Ethiopia are seen as 10 pursuing national interests that are not invested in Somali peace and stability. The study concludes that US extra-judicial killings have failed to constrain the actions of al-Shabaab. Somalis expressed that the leadership of current president, Mohamed Abdullahi Mohamed Farmaajo, holds the unique possibilities of creating national unity that rises above clan divisions and the radical Jihadist ideology of al-Shabaab.
- Full Text:
- Date Issued: 2019
- Authors: Koloko, Mojalefa
- Date: 2019
- Subjects: Somalia -- Politics and government -- 1991- , Somalia -- History -- 1991- , Somalia -- Foreign relations -- United States , Somalia -- Foreign relations -- 1991- , Military assistance, American -- Somalia , Extrajudicial exeutions -- Somalia , Shabaab (Organization)
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/67657 , vital:29125
- Description: This study examines the nature of the United States intervention in Somalia, specifically the use of drone strikes that first targeted the militant Sunni Islamist transnational group, al-Qaeda, which claimed responsibility for the 11 September 2001 attacks on the United States, and now target the Somali organisation, Harakat al-Shabaab al-Mujahidin, commonly known as al-Shabaab. The use of drone strikes in the US led war on terror has raised concerns about sovereignty as the extra-judicial killings are conducted without the consent of the concerned states. Furthermore, drone strikes also raise questions about the processes of liberal intervention as the US conducts them without the approval of the United Nations Security Council. It is argued in this study that what is understood to be the “golden era” of liberal interventionism is a legacy of the post-Cold War unipolar dominance of the United States in global governance and security. It is argued that US unipolarity was accompanied by a shifting perception regarding the security position of weak states, whose weakness becomes understood as a source of global insecurity. This perception that so called “weak” and “fragile” states are sources of threats is a departure in International Relations theory, because the discipline is historically preoccupied with studying the actions of powerful states and their consequence for the global order. It is argued that the discourse on the war on terror, and its focus on “failed states” as breeding grounds for alleged terrorists, represents the height of the repositioning of less powerful states from a peripheral status in IR analysis and practice, to their current position that are now being represented as core sources of threat to international peace and security. Through life history interviews with Somali nationals in Grahamstown, Port Elizabeth and Uitenhage, South Africa, the study examines the consequences of US actions from the eyes of Somali people. The findings of this study show that despite all the controversy surrounding the legitimacy of the war on terror, the manner in which it is conducted, as well as the tactics that it employs, the majority of Somali participants showed an overwhelming support for the US intervention. Participants expressed support for the US extra-judicial killings because they are understood to undermine al-Shabaab strength which is a major source of insecurity. The study also shows that the lack of necessary collaboration between the US intelligence and the Somali ground forces has resulted in high numbers of civilian deaths, which participants fear can be used by al-Shabaab to recruit and radicalise more Somalis. The study also shows that most Somalis resent the presence of the African Union Mission in Somalia because Kenya and Ethiopia are seen as 10 pursuing national interests that are not invested in Somali peace and stability. The study concludes that US extra-judicial killings have failed to constrain the actions of al-Shabaab. Somalis expressed that the leadership of current president, Mohamed Abdullahi Mohamed Farmaajo, holds the unique possibilities of creating national unity that rises above clan divisions and the radical Jihadist ideology of al-Shabaab.
- Full Text:
- Date Issued: 2019
Beyond Pierre Hadot’s promethean and orphic framework: critical reflections on Leonardo Dicaprio’s environmental documentaries in relation to the veil of ISIS
- Authors: Kotze, Mieke
- Date: 2019
- Subjects: Philosophy of nature , Documentary films -- United States -- History and criticism Environmental films -- United States -- History and criticism Motion pictures -- United States -- History -- 21st century
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/40599 , vital:36186
- Description: In his book The Veil of Isis: An Essay on the History of the Idea of Nature (2006), Pierre Hadot details two opposing paradigmatic attitudes to nature that have prevailed over the ages, namely, the Promethean and Orphic approaches, which entail, respectively, the violent unmasking of nature’s secrets through technology and the gentle approximation of them through aesthetic means. However, while this dichotomy does constitute a useful tool for understanding broad attitudes toward nature, it does not allow for consideration of the more nuanced, responses to nature across the various epochs, including the contemporary context of the looming ecological crisis. For this reason in what follows, Hadot’s Promethean-Orphic binary will be extended into a more comprehensive framework that allows for the contemplation of three additional approaches to nature, namely Socratic withdrawal, Aristotelian-inspired faith in teleology and the Hippocratic pursuit of balance with nature – which Hadot sees as either displaced by or incorporated into the Promethean attitude. Thereafter, various historical epochs will be explored through the lens of this extended Hadotian framework in order to assess the manner in which the abovementioned attitudes and approaches to nature have been adopted and progressively rearticulated, from Archaic Greece to Deleuze’s control society. And it will be advanced that, while at the outset, these approaches were more or less equivalent in terms of their discursive influence, over time Prometheanism, and the rearticulated permutations of Socratic withdrawal and Aristotelian-inspired faith in teleology, have combined to constitute what is here referred to as the Promethean/Socratic/Aristotelian nexus; a nexus which, as will be discussed, has progressively eclipsed the less invasive approaches of Hippocratic balance and Orphism, to the detriment of both nature and human relations to it. The progression of such tendencies will then be examined in relation to the two contemporary environmental films associated with Leonardo DiCaprio, namely The 11th Hour (2007) and Before the Flood (2016). This will be done in order to draw into conspicuity the intensification of discourses surrounding the technological dominance of the environment by humans who have withdrawn from nature, inspired by faith in the telos of the free-market economy, along with and the attendant marginalization of balance-seeking and aesthetically-oriented approaches to nature. Furthermore, it will be advanced, in concluding that such discursive patterns could account for the widespread apathy and indifference which characterizes contemporary responses to the environmental crisis.
- Full Text:
- Date Issued: 2019
- Authors: Kotze, Mieke
- Date: 2019
- Subjects: Philosophy of nature , Documentary films -- United States -- History and criticism Environmental films -- United States -- History and criticism Motion pictures -- United States -- History -- 21st century
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/40599 , vital:36186
- Description: In his book The Veil of Isis: An Essay on the History of the Idea of Nature (2006), Pierre Hadot details two opposing paradigmatic attitudes to nature that have prevailed over the ages, namely, the Promethean and Orphic approaches, which entail, respectively, the violent unmasking of nature’s secrets through technology and the gentle approximation of them through aesthetic means. However, while this dichotomy does constitute a useful tool for understanding broad attitudes toward nature, it does not allow for consideration of the more nuanced, responses to nature across the various epochs, including the contemporary context of the looming ecological crisis. For this reason in what follows, Hadot’s Promethean-Orphic binary will be extended into a more comprehensive framework that allows for the contemplation of three additional approaches to nature, namely Socratic withdrawal, Aristotelian-inspired faith in teleology and the Hippocratic pursuit of balance with nature – which Hadot sees as either displaced by or incorporated into the Promethean attitude. Thereafter, various historical epochs will be explored through the lens of this extended Hadotian framework in order to assess the manner in which the abovementioned attitudes and approaches to nature have been adopted and progressively rearticulated, from Archaic Greece to Deleuze’s control society. And it will be advanced that, while at the outset, these approaches were more or less equivalent in terms of their discursive influence, over time Prometheanism, and the rearticulated permutations of Socratic withdrawal and Aristotelian-inspired faith in teleology, have combined to constitute what is here referred to as the Promethean/Socratic/Aristotelian nexus; a nexus which, as will be discussed, has progressively eclipsed the less invasive approaches of Hippocratic balance and Orphism, to the detriment of both nature and human relations to it. The progression of such tendencies will then be examined in relation to the two contemporary environmental films associated with Leonardo DiCaprio, namely The 11th Hour (2007) and Before the Flood (2016). This will be done in order to draw into conspicuity the intensification of discourses surrounding the technological dominance of the environment by humans who have withdrawn from nature, inspired by faith in the telos of the free-market economy, along with and the attendant marginalization of balance-seeking and aesthetically-oriented approaches to nature. Furthermore, it will be advanced, in concluding that such discursive patterns could account for the widespread apathy and indifference which characterizes contemporary responses to the environmental crisis.
- Full Text:
- Date Issued: 2019
Bioavailability of nutrients in a diet enriched with moringa oleifera lam. Leaves using wistar rats
- Authors: Mhlomi, Yanga Nonelela
- Date: 2019
- Subjects: Moringa Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14594 , vital:40018
- Description: This study investigated the nutritional composition and bioavailability of nutrients in Moringa oleifera leaf meal from South African ecotype. Nutritional evaluation (proximate, mineral, vitamins and antinutrients, amino acids and fatty acids analyses) was performed using AOAC, ICP-OES and GC+MS techniques respectively. Bioavailability of nutrients involved formulation of diets deficient in minerals and vitamins; and proteins supplemented with Moringa oleifera leaf meal (MOLM) at 0, 3, 5 and 10% respectively. Growth performance, hematological, biochemical and histopathological evaluations were used to assess the effect of MOLM supplementation. Proximate and mineral evaluation revealed that the leaves were rich in protein (28.72%) and carbohydrate (28.84%), calcium content was (1603.33 mg/100g), potassium (1690 mg/100g), zinc (13.03 mg/100g) and iron (21.13 mg/100g). Vitamin E content was the highest (89.43 mg/100g) followed by vitamic C (24.9 mg/100g) and vitamin A (12.98 mg/100g). Fatty acids analysis detected were fifteen of which polyunsaturated fatty acid linoleic acid (56.36) and alpha-linolenic acid (687.58) were highest and behenic acid (22:0) characteristics of Moringa (4.11%) were detected. Seven of the detected fatty acids were saturated fatty acids, though relatively low, with stearic acid having the highest value. On the other hand fifteen of the amino acids, 7 were essential (valine, leucine, isoleucine, methionine, threonine and phenylalanine) were detected; while alanine, proline, serine, aspartic acid, cysteine, glutamic acid, asparagine and tyrosine were non- essential amino acid. Moringa oleifera had low quantities of antinutrients in relation to minerals, thus nutrients will easily ne available. Amino and fatty acids profile of nutrient deficient diets supplemented with MOLM revealed that six essential amino acids were detected in the diets. However, the essential amino acid (EAA) in MOLM with the highest value was threonine (500.47±23.03mg/L), while the lowest was methionine (75.65±5.31mg/L). Leucine was highest in PD10 (234.32±27.98 mg/l) 15 and lowest in PD3. Predominant amino acid in VMD diet was glutamic acid (966.76±208.92 mg/l), while methionine was lowest (197.14±35.90). Caproic acid was the most prominent unsaturated fatty acid in the diets and was highest in the PD diet. Palmitoleic acid was highest in the control diet (8.19±0.56 mg/L) and lowest in PD3 but an increase was observed as the levels of MOLM increased in the diets. Linoleic acid values obtained were significantly higher in PD diet, lower in control diet, compared to other diets. Linolenic acid (C18-3n6) was higher in PD10 (63.48±3.84 mg/L) compared to the control diet (6.05±0.14 mg/L). The highest unsaturated fatty acid in all the feed samples was linoleic acids ranging from 54.48±5.61 to 296.26±7.20 mg/L. the highest omega-3 (n-3) fatty acid content (63.48±3.38 mg/L) was in PD10 and was almost 10 times higher than the value recorded for control. Rats treated on vitamin mineral deficient (VMD) diet showed no significant changes in growth performances and blood parameters except in certain indices. Rats on VMD diet had lowest haemoglobin levels, whereas haemoglobin increased with MOLM levels. No significant differences in haematocrit, MCH, MCHC, platelets, RDW and MPV were observed in all treatments and control. However, VMD rats showed decrease in haemoglobin, increase in WBC and platelets. Electrolytes and glucose for all treatments and control were not significantly different, but, control and VMD10 diets rats showed significantly higher values for creatinine compared to MOLM diets; total protein and albumin increased with MOLM and were higher than in VMD and control rats. Serum activities of liver, cardiac, adrenal marker enzymes were significantly lower in MOLM rats compared to VMD and control. Mild congestion in VMD and VMD3 rat’s liver and diffused congestion in the kidney of VMD diet fed rats was observed. Protein deficient diets supplemented with MOLM had a negative impact on feed intake and growth parameters. Rats fed PD and PD5 consumed significantly less diet than those fed PD10, PD3 diets respectively. White blood cells decreased with increasing levels of MOLM 16 supplementation. Differential white cell count (Neutrophils, lymphocytes, monocytes, eosinophils and basophils) followed the same trend though not statistically significant (P>0.05). Furthermore, histopathological evaluation of organs revealed that no abnormalities were in heart and liver and kidney of rats fed on the control diet, while mild congestion in the liver and myocardium (heart) were observed in rats fed with protein deficient diet. No visible abnormalities were observed in the heart, kidney and liver of animals on the PD 10 diet, but myocardial fibres showing intense eosinophilia was detected in heart muscles of rats fed PD and PD3 diets. In this study, MOLM had a negative impact on feed intake and growth performance of animals and haematology. Blood biochemistry and histology suggest that MOLM has the potential of defending the body against infection with hematinic and blood enhancing qualities. Protein deficiency led to a significant elevation in the serum lipid profile of rats especially cholesterol even with increase in MOLM. PD10 had the highest triglycerides content when compared to the control but was lower (p>0.05) to that of PD. There was an increase in crude fat, ADF, NDF and protein in faecal samples of rats supplemented with MOLM diets while a decrease in moisture and ash was observed compared to the control.Vitamin and mineral deficiency resulted in significant decrease in serum cholesterol, triglycerides and HDL-C when compared to the control. There was a slight increase in excretion for all elements with increasing MOLM. Total removal of minerals and vitamins from the VMD experimental diets seemed not to have any visible negative impact on performance of the rats probably because of residual micronutrients present in other ingredients used in the feed formulation. MOLM could not replace protein in protein deficient diets.
- Full Text:
- Date Issued: 2019
- Authors: Mhlomi, Yanga Nonelela
- Date: 2019
- Subjects: Moringa Medicinal plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14594 , vital:40018
- Description: This study investigated the nutritional composition and bioavailability of nutrients in Moringa oleifera leaf meal from South African ecotype. Nutritional evaluation (proximate, mineral, vitamins and antinutrients, amino acids and fatty acids analyses) was performed using AOAC, ICP-OES and GC+MS techniques respectively. Bioavailability of nutrients involved formulation of diets deficient in minerals and vitamins; and proteins supplemented with Moringa oleifera leaf meal (MOLM) at 0, 3, 5 and 10% respectively. Growth performance, hematological, biochemical and histopathological evaluations were used to assess the effect of MOLM supplementation. Proximate and mineral evaluation revealed that the leaves were rich in protein (28.72%) and carbohydrate (28.84%), calcium content was (1603.33 mg/100g), potassium (1690 mg/100g), zinc (13.03 mg/100g) and iron (21.13 mg/100g). Vitamin E content was the highest (89.43 mg/100g) followed by vitamic C (24.9 mg/100g) and vitamin A (12.98 mg/100g). Fatty acids analysis detected were fifteen of which polyunsaturated fatty acid linoleic acid (56.36) and alpha-linolenic acid (687.58) were highest and behenic acid (22:0) characteristics of Moringa (4.11%) were detected. Seven of the detected fatty acids were saturated fatty acids, though relatively low, with stearic acid having the highest value. On the other hand fifteen of the amino acids, 7 were essential (valine, leucine, isoleucine, methionine, threonine and phenylalanine) were detected; while alanine, proline, serine, aspartic acid, cysteine, glutamic acid, asparagine and tyrosine were non- essential amino acid. Moringa oleifera had low quantities of antinutrients in relation to minerals, thus nutrients will easily ne available. Amino and fatty acids profile of nutrient deficient diets supplemented with MOLM revealed that six essential amino acids were detected in the diets. However, the essential amino acid (EAA) in MOLM with the highest value was threonine (500.47±23.03mg/L), while the lowest was methionine (75.65±5.31mg/L). Leucine was highest in PD10 (234.32±27.98 mg/l) 15 and lowest in PD3. Predominant amino acid in VMD diet was glutamic acid (966.76±208.92 mg/l), while methionine was lowest (197.14±35.90). Caproic acid was the most prominent unsaturated fatty acid in the diets and was highest in the PD diet. Palmitoleic acid was highest in the control diet (8.19±0.56 mg/L) and lowest in PD3 but an increase was observed as the levels of MOLM increased in the diets. Linoleic acid values obtained were significantly higher in PD diet, lower in control diet, compared to other diets. Linolenic acid (C18-3n6) was higher in PD10 (63.48±3.84 mg/L) compared to the control diet (6.05±0.14 mg/L). The highest unsaturated fatty acid in all the feed samples was linoleic acids ranging from 54.48±5.61 to 296.26±7.20 mg/L. the highest omega-3 (n-3) fatty acid content (63.48±3.38 mg/L) was in PD10 and was almost 10 times higher than the value recorded for control. Rats treated on vitamin mineral deficient (VMD) diet showed no significant changes in growth performances and blood parameters except in certain indices. Rats on VMD diet had lowest haemoglobin levels, whereas haemoglobin increased with MOLM levels. No significant differences in haematocrit, MCH, MCHC, platelets, RDW and MPV were observed in all treatments and control. However, VMD rats showed decrease in haemoglobin, increase in WBC and platelets. Electrolytes and glucose for all treatments and control were not significantly different, but, control and VMD10 diets rats showed significantly higher values for creatinine compared to MOLM diets; total protein and albumin increased with MOLM and were higher than in VMD and control rats. Serum activities of liver, cardiac, adrenal marker enzymes were significantly lower in MOLM rats compared to VMD and control. Mild congestion in VMD and VMD3 rat’s liver and diffused congestion in the kidney of VMD diet fed rats was observed. Protein deficient diets supplemented with MOLM had a negative impact on feed intake and growth parameters. Rats fed PD and PD5 consumed significantly less diet than those fed PD10, PD3 diets respectively. White blood cells decreased with increasing levels of MOLM 16 supplementation. Differential white cell count (Neutrophils, lymphocytes, monocytes, eosinophils and basophils) followed the same trend though not statistically significant (P>0.05). Furthermore, histopathological evaluation of organs revealed that no abnormalities were in heart and liver and kidney of rats fed on the control diet, while mild congestion in the liver and myocardium (heart) were observed in rats fed with protein deficient diet. No visible abnormalities were observed in the heart, kidney and liver of animals on the PD 10 diet, but myocardial fibres showing intense eosinophilia was detected in heart muscles of rats fed PD and PD3 diets. In this study, MOLM had a negative impact on feed intake and growth performance of animals and haematology. Blood biochemistry and histology suggest that MOLM has the potential of defending the body against infection with hematinic and blood enhancing qualities. Protein deficiency led to a significant elevation in the serum lipid profile of rats especially cholesterol even with increase in MOLM. PD10 had the highest triglycerides content when compared to the control but was lower (p>0.05) to that of PD. There was an increase in crude fat, ADF, NDF and protein in faecal samples of rats supplemented with MOLM diets while a decrease in moisture and ash was observed compared to the control.Vitamin and mineral deficiency resulted in significant decrease in serum cholesterol, triglycerides and HDL-C when compared to the control. There was a slight increase in excretion for all elements with increasing MOLM. Total removal of minerals and vitamins from the VMD experimental diets seemed not to have any visible negative impact on performance of the rats probably because of residual micronutrients present in other ingredients used in the feed formulation. MOLM could not replace protein in protein deficient diets.
- Full Text:
- Date Issued: 2019
Biochemical characterization of the β-mannanase activity of Bacillus paralicheniformis SVD1
- Authors: Clarke, Matthew David
- Date: 2019
- Subjects: Mycobacterium avium paratuberculosis , Enzymes -- Biotechnology , Lignocellulose -- Biotechnology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67570 , vital:29112
- Description: Products produced via the enzymatic hydrolysis of lignocellulosic biomass, the most abundant renewable terrestrial source of carbon, can potentially replace a lot of the fuels and chemicals currently produced using non-renewable hydrocarbons. Mannan is a polysaccharide component of lignocellulose that is abundant in softwoods and legume seeds. Enzymatic hydrolysis of mannan by β-mannanases has various industrial applications, including use in biofuel and prebiotic mannooligosaccharide (MOS) production for the improvement of human and animal health. The industrial use of β-mannanases depends on their biochemical characteristics, such as their activity, stability and substrate specificity. Knowledge of their synergistic interactions with other enzymes is also useful for effective hydrolysis. Bacillus paralicheniformis SVD1 was used as a source for β-mannanases. The two mannanases of B. paralicheniformis SVD1 have not been biochemically characterized apart from minor characterization of crude β-mannanase activity. The protein sequences of the two β-mannanases, of glycosyl hydrolase family 5 and 26, have a 95% - 96% identity to the β-mannanases of B. licheniformis DSM13T (=ATCC14580T). These small protein sequence differences could lead to quite different biochemical characteristics. These mannanases were characterized as these enzymes may have industrially useful characteristics. To induce mannanase production, B. paralicheniformis SVD1 was cultured in broth containing the mannan substrate locust bean gum. Various growth curve parameters were measured over 72 h. Mannanase activity was the highest after 48 h of growth - this was the time at which mannanase activity was concentrated, using 3 kDa centrifugal filtration devices, for biochemical characterization of the crude activity. Zymography revealed that the crude concentrated mannanase fraction consisted of at least two mannanases with relative molecular weights (MWs) of 29.6 kDa and 33 kDa. This was smaller than expected – based on their theoretical molecular masses. Protease activity, which was detected in the broth, was probably the reason. There were two pH optima, pH 5.0 and pH 7.0, which also indicated the presence of two mannanases. The concentrated mannanase displayed characteristics that were expected of a B. paralicheniformis β-mannanase. The temperature optimum was 50°C and the activity loss was less than 7% at 50°C after 24 h. Substrate specificity assays revealed that there was predominantly mannanase activity present. Thin layer chromatography (TLC) analysis of mannan and MOS hydrolysis showed that mainly M2 and M3 MOS were produced; only MOS with a degree of polymerization of 4 or higher were hydrolyzed. Hydrolysis was minimal on mannoligosaccharides with galactose substituents. Activity and MOS production was the highest on soluble, low branched mannan substrates. The highest activity observed was on konjac glucomannan. Purification of the mannanase activity was then attempted using various methods. Ammonium sulfate precipitation, acetone precipitation, as well as centrifugal filtration device concentration was assessed for concentration of the mannanase activity.Concentration was not very successful due to low activity yields (≤ 20%). Anion exchange chromatography (AEC) and size exclusion chromatography (SEC) was used for purification. AEC gave good activity yield and fold purification, but SDS-PAGE analysis revealed the presence of many different proteins so further purification was necessary. SDS-PAGE analysis showed that there were only a few protein contaminants in the SEC fraction. However, the yield was too low to allow for biochemical characterization. The optimized purification procedure, which partially purified the mannanase activity, used 85% ammonium sulfate precipitation, followed by AEC. The fold purification was high (88.9) and the specific activity was 29.5 U.mg-1. A zymogram of the partially purified mannanase showed a mannanase active band with a MW of 40 - 41 kDa. A serine protease inhibitor, phenylmethylsulfonyl fluoride (PMSF), was added during the purification steps. This indicated that the mannanase/s in the crude concentrate, without PMSF added, was hydrolyzed by serine protease activity. Native PAGE zymograms suggested that at least two different isoforms of mannanases were present. Additional purification would be required to determine the true characteristics of the mannanase/s. The biochemical characteristics of the crude and partially purified mannanases were similar. The pH optima of the partially purified mannanases were different; the pH optima were 6.0 and 9.0. The substrate specificities were similar, except that the partially purified mannanases displayed no cellulase and β-D-galactosidase activity, but showed a small amount of α-L-arabinase activity. The partially purified mannanase and a Cyamopsis tetragonolobus GH27 α-galactosidase synergistically hydrolyzed locust bean gum. The M50G50 combination displayed the highest extent of hydrolysis; after 24 h there was a 1.39 fold increase in reducing sugar release and the degree of synergy (DS) was 4.64. TLC analysis indicated that synergy increased the release of small MOS. These MOS could be useful as prebiotics. The synergy between the partially purified mannanase and the commercial cellulase mixture Cellic® CTec2 (Novozymes) on spent coffee grounds (SCG) was also determined. SCG is an abundant industrial waste product that has high mannan content. The SCG was pretreated using NaOH, and the monosaccharide, soluble phenolics and insoluble contents were determined. Glucose and mannose were the dominant monosaccharides in the SCG; the pretreated SCG contained 20.4% (w/w) glucose and 18.5% (w/w) mannose, respectively. The NaOH pretreatment improved mannanase hydrolysis of SCG. It resulted in the opening up and swelling of the SCG particles and removed some of the insoluble solids. The partially purified B. paralicheniformis SVD1 mannanase displayed no detectable activity on SCG, but showed synergy with CTec2, in terms of DS, on untreated and NaOH pretreated SCG. This is the first report of mannanasecellulase synergy on SCG; other studies found that increased hydrolysis was due to additive effects. The results obtained in this study are only an initial assessment of the biochemical properties of B. paralicheniformis SVD1 mannanase activity and its synergy with other enzymes. These results can be used to inform future studies.
- Full Text:
- Date Issued: 2019
- Authors: Clarke, Matthew David
- Date: 2019
- Subjects: Mycobacterium avium paratuberculosis , Enzymes -- Biotechnology , Lignocellulose -- Biotechnology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67570 , vital:29112
- Description: Products produced via the enzymatic hydrolysis of lignocellulosic biomass, the most abundant renewable terrestrial source of carbon, can potentially replace a lot of the fuels and chemicals currently produced using non-renewable hydrocarbons. Mannan is a polysaccharide component of lignocellulose that is abundant in softwoods and legume seeds. Enzymatic hydrolysis of mannan by β-mannanases has various industrial applications, including use in biofuel and prebiotic mannooligosaccharide (MOS) production for the improvement of human and animal health. The industrial use of β-mannanases depends on their biochemical characteristics, such as their activity, stability and substrate specificity. Knowledge of their synergistic interactions with other enzymes is also useful for effective hydrolysis. Bacillus paralicheniformis SVD1 was used as a source for β-mannanases. The two mannanases of B. paralicheniformis SVD1 have not been biochemically characterized apart from minor characterization of crude β-mannanase activity. The protein sequences of the two β-mannanases, of glycosyl hydrolase family 5 and 26, have a 95% - 96% identity to the β-mannanases of B. licheniformis DSM13T (=ATCC14580T). These small protein sequence differences could lead to quite different biochemical characteristics. These mannanases were characterized as these enzymes may have industrially useful characteristics. To induce mannanase production, B. paralicheniformis SVD1 was cultured in broth containing the mannan substrate locust bean gum. Various growth curve parameters were measured over 72 h. Mannanase activity was the highest after 48 h of growth - this was the time at which mannanase activity was concentrated, using 3 kDa centrifugal filtration devices, for biochemical characterization of the crude activity. Zymography revealed that the crude concentrated mannanase fraction consisted of at least two mannanases with relative molecular weights (MWs) of 29.6 kDa and 33 kDa. This was smaller than expected – based on their theoretical molecular masses. Protease activity, which was detected in the broth, was probably the reason. There were two pH optima, pH 5.0 and pH 7.0, which also indicated the presence of two mannanases. The concentrated mannanase displayed characteristics that were expected of a B. paralicheniformis β-mannanase. The temperature optimum was 50°C and the activity loss was less than 7% at 50°C after 24 h. Substrate specificity assays revealed that there was predominantly mannanase activity present. Thin layer chromatography (TLC) analysis of mannan and MOS hydrolysis showed that mainly M2 and M3 MOS were produced; only MOS with a degree of polymerization of 4 or higher were hydrolyzed. Hydrolysis was minimal on mannoligosaccharides with galactose substituents. Activity and MOS production was the highest on soluble, low branched mannan substrates. The highest activity observed was on konjac glucomannan. Purification of the mannanase activity was then attempted using various methods. Ammonium sulfate precipitation, acetone precipitation, as well as centrifugal filtration device concentration was assessed for concentration of the mannanase activity.Concentration was not very successful due to low activity yields (≤ 20%). Anion exchange chromatography (AEC) and size exclusion chromatography (SEC) was used for purification. AEC gave good activity yield and fold purification, but SDS-PAGE analysis revealed the presence of many different proteins so further purification was necessary. SDS-PAGE analysis showed that there were only a few protein contaminants in the SEC fraction. However, the yield was too low to allow for biochemical characterization. The optimized purification procedure, which partially purified the mannanase activity, used 85% ammonium sulfate precipitation, followed by AEC. The fold purification was high (88.9) and the specific activity was 29.5 U.mg-1. A zymogram of the partially purified mannanase showed a mannanase active band with a MW of 40 - 41 kDa. A serine protease inhibitor, phenylmethylsulfonyl fluoride (PMSF), was added during the purification steps. This indicated that the mannanase/s in the crude concentrate, without PMSF added, was hydrolyzed by serine protease activity. Native PAGE zymograms suggested that at least two different isoforms of mannanases were present. Additional purification would be required to determine the true characteristics of the mannanase/s. The biochemical characteristics of the crude and partially purified mannanases were similar. The pH optima of the partially purified mannanases were different; the pH optima were 6.0 and 9.0. The substrate specificities were similar, except that the partially purified mannanases displayed no cellulase and β-D-galactosidase activity, but showed a small amount of α-L-arabinase activity. The partially purified mannanase and a Cyamopsis tetragonolobus GH27 α-galactosidase synergistically hydrolyzed locust bean gum. The M50G50 combination displayed the highest extent of hydrolysis; after 24 h there was a 1.39 fold increase in reducing sugar release and the degree of synergy (DS) was 4.64. TLC analysis indicated that synergy increased the release of small MOS. These MOS could be useful as prebiotics. The synergy between the partially purified mannanase and the commercial cellulase mixture Cellic® CTec2 (Novozymes) on spent coffee grounds (SCG) was also determined. SCG is an abundant industrial waste product that has high mannan content. The SCG was pretreated using NaOH, and the monosaccharide, soluble phenolics and insoluble contents were determined. Glucose and mannose were the dominant monosaccharides in the SCG; the pretreated SCG contained 20.4% (w/w) glucose and 18.5% (w/w) mannose, respectively. The NaOH pretreatment improved mannanase hydrolysis of SCG. It resulted in the opening up and swelling of the SCG particles and removed some of the insoluble solids. The partially purified B. paralicheniformis SVD1 mannanase displayed no detectable activity on SCG, but showed synergy with CTec2, in terms of DS, on untreated and NaOH pretreated SCG. This is the first report of mannanasecellulase synergy on SCG; other studies found that increased hydrolysis was due to additive effects. The results obtained in this study are only an initial assessment of the biochemical properties of B. paralicheniformis SVD1 mannanase activity and its synergy with other enzymes. These results can be used to inform future studies.
- Full Text:
- Date Issued: 2019
Biogenic synthesis of Silver nanoparticles (AgNPs) and its effects on Zebrafish (Danio rerio)
- Authors: Siguba, Busiswa
- Date: 2019
- Subjects: Biogenic synthesis -- Zebrafish , Nanoparticles – Silver , Zebrafish
- Language: English
- Type: Thesis , Masters , M Sc
- Identifier: http://hdl.handle.net/11260/1339 , vital:32260
- Description: The increase in use and production of engineered nanoparticles in recent years points towards their inevitable release into freshwater ecosystems. Subsequently, exposure to organisms in freshwater ecosystems is to be expected. The aim of this dissertation was to synthesize silver nanoparticles (AgNPs) using silver nitrate, gelatine and maltose as precursor, capping and reducing agent respectively. Cytotoxic effects of the as-synthesized AgNPs was evaluated at concentrations of 0.031 μg/L, 0.250 μg/L and 5.000 μg/L on selected target organs in zebrafish (Danio rerio ) after 96 hr of exposure, under a 24 hr static renewal system. Formation of AgNPs was investigated by UV-Vis spectrophotometry, which displayed absorption maxima peak characteristic of plasmon resonance band for silver at 419 nm. From transmission electron microscopy, AgNPs was found to be small, well dispersed and spherical in shape with a narrow size distribution, and an average particle size of3.76 ± 1.00 nm. Histopathological alterations following exposure to AgNPs was noticed in the gills, epidermis, muscle tissue and kidney. Secondary lamellae hypertrophy, oedema and epithelial lifting was observed in all experimental groups. Curling and clubbed tips of secondary lamellae were observed at the lowest concentration (0.031 μg/L). Hyperplasia and lamellae fusion was most common at the median concentration (0.250 μg/L) of AgNP exposure. Hypertrophy of endothelial cells along with blood vessel congestion was also observed. Reduced secondary lamellar length, lamellar erosion and thinning were observed at the highest concentration (5.000 μg/L).AgNP exposure also altered the shape of alarm cells. In addition, hyperplasia and hypertrophy of goblet cells were observed at the highest concentration (5.000 μg/L) at 96 hr. At 5.000 μg/L of AgNP, PAS reaction was intense (deep purple), while the number and size of these cells decreased. Staining with AB pH 2.5 demonstrated an intense deep purple staining at the lowest and at the median concentration (24 hr). Moderate staining was seen at the higher concentrations. Muscle bundles with severe oedema, their thickening and separation were more pronounced in all treated groups. Histopathological tubular deformation and mononuclear cell infiltration were observed in kidney tissues. In addition; an increase in melano‐macrophage aggregation intensity was identified on the 48 hr in the treated groups. An increase in tubular epithelial cell regeneration/ proliferation, resulting in production of new epithelial cells which was indicative of recovering of kidney tissues from AgNP induced injury at 96 hr of exposure. Results presented here shows that fish respond to the presence of AgNPs.
- Full Text:
- Date Issued: 2019
- Authors: Siguba, Busiswa
- Date: 2019
- Subjects: Biogenic synthesis -- Zebrafish , Nanoparticles – Silver , Zebrafish
- Language: English
- Type: Thesis , Masters , M Sc
- Identifier: http://hdl.handle.net/11260/1339 , vital:32260
- Description: The increase in use and production of engineered nanoparticles in recent years points towards their inevitable release into freshwater ecosystems. Subsequently, exposure to organisms in freshwater ecosystems is to be expected. The aim of this dissertation was to synthesize silver nanoparticles (AgNPs) using silver nitrate, gelatine and maltose as precursor, capping and reducing agent respectively. Cytotoxic effects of the as-synthesized AgNPs was evaluated at concentrations of 0.031 μg/L, 0.250 μg/L and 5.000 μg/L on selected target organs in zebrafish (Danio rerio ) after 96 hr of exposure, under a 24 hr static renewal system. Formation of AgNPs was investigated by UV-Vis spectrophotometry, which displayed absorption maxima peak characteristic of plasmon resonance band for silver at 419 nm. From transmission electron microscopy, AgNPs was found to be small, well dispersed and spherical in shape with a narrow size distribution, and an average particle size of3.76 ± 1.00 nm. Histopathological alterations following exposure to AgNPs was noticed in the gills, epidermis, muscle tissue and kidney. Secondary lamellae hypertrophy, oedema and epithelial lifting was observed in all experimental groups. Curling and clubbed tips of secondary lamellae were observed at the lowest concentration (0.031 μg/L). Hyperplasia and lamellae fusion was most common at the median concentration (0.250 μg/L) of AgNP exposure. Hypertrophy of endothelial cells along with blood vessel congestion was also observed. Reduced secondary lamellar length, lamellar erosion and thinning were observed at the highest concentration (5.000 μg/L).AgNP exposure also altered the shape of alarm cells. In addition, hyperplasia and hypertrophy of goblet cells were observed at the highest concentration (5.000 μg/L) at 96 hr. At 5.000 μg/L of AgNP, PAS reaction was intense (deep purple), while the number and size of these cells decreased. Staining with AB pH 2.5 demonstrated an intense deep purple staining at the lowest and at the median concentration (24 hr). Moderate staining was seen at the higher concentrations. Muscle bundles with severe oedema, their thickening and separation were more pronounced in all treated groups. Histopathological tubular deformation and mononuclear cell infiltration were observed in kidney tissues. In addition; an increase in melano‐macrophage aggregation intensity was identified on the 48 hr in the treated groups. An increase in tubular epithelial cell regeneration/ proliferation, resulting in production of new epithelial cells which was indicative of recovering of kidney tissues from AgNP induced injury at 96 hr of exposure. Results presented here shows that fish respond to the presence of AgNPs.
- Full Text:
- Date Issued: 2019
Bioinformatic analysis, isolation and kinetic characterisation of red algae (Gelidium capense) dehydrogenases
- Authors: Gogela, Yanga
- Date: 2019
- Subjects: Bioinformatics Chondrus crispus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19164 , vital:39878
- Description: Lactate and alcohol dehydrogenases have attracted much attention in various industries and scientific research for their ability to produce chirally pure compounds and be assayed for activity using more straightforward and reproducible assay methods. These enzymes have been previously isolated and purified from various plants, animals and microorganisms. So far, the molecular and biochemical properties of enzymes from these dehydrogenase families in red algae are mostly unknown. Red macroalgae have been used for centuries for the treatment of various diseases and as a source of ingredients in the food industry. The aim of this study was to identify genes in the sequenced red algae genomes that encode dehydrogenases, to use bioinformatic tools to confirm that the proteins encoded are dehydrogenases and to isolate and kinetically purify alcohol or lactate dehydrogenase from red algae species found along the coastline of the Eastern Cape Province. A combination of bioinformatics tools, molecular and biochemical techniques were used to identify, purify, and characterise ADH and LDH enzymes. Bioinformatics analysis revealed two alcohol dehydrogenase genes and two hypothetical genes encoding functional domains similar to D-lactate dehydrogenases from other species. The ADH and LDH-like genes shared low sequence identity at the protein level with medium-chain dehydrogenases/reductases (MDRs) and 2-hydroxy acid dehydrogenases, respectively. These two dehydrogenase genes showed a highly conserved NAD-binding motif (Rossmann-fold) similar to many other NAD-dependent dehydrogenases. The ADH and LDH proteins contained no signal peptides and may be located in the cytoplasm. The phylogenetic tree analysis showed that the two ADH genes belonged to cinnamyl and class III alcohol dehydrogenases, whereas the LDHlike genes were grouped with D-lactate dehydrogenases from other organisms. The ADH and LDH gene family showed cis-acting regulatory elements that are mostly involved in stress response and hormonal response. Structural analysis showed that the dehydrogenases 3D structure predicted models comprise of two domains, namely the substrate binding and the coenzyme binding domains that are rich in beta-strands secondary structure elements. The LDH from red algae was purified approximately 4-fold with a specific activity of 0.044 U/mg. The purified LDH enzyme had a molecular weight of approximately 37kDa. The LDH was active across a broad pH range from 5-9 with a pH optimum observed at 7.5. The LDH ii enzyme in red algae exhibits a temperature optimum of 40 ⁰C and heat stability up to 40 ⁰C. Above 50 °C the LDH activity rapidly decreased showing that the LDH in red algae is not thermostable. The LDH enzyme showed a Km value of 0.8 mM and Vmax of 0.0067 mM.min-1 when using sodium pyruvate as a substrate.
- Full Text:
- Date Issued: 2019
- Authors: Gogela, Yanga
- Date: 2019
- Subjects: Bioinformatics Chondrus crispus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/19164 , vital:39878
- Description: Lactate and alcohol dehydrogenases have attracted much attention in various industries and scientific research for their ability to produce chirally pure compounds and be assayed for activity using more straightforward and reproducible assay methods. These enzymes have been previously isolated and purified from various plants, animals and microorganisms. So far, the molecular and biochemical properties of enzymes from these dehydrogenase families in red algae are mostly unknown. Red macroalgae have been used for centuries for the treatment of various diseases and as a source of ingredients in the food industry. The aim of this study was to identify genes in the sequenced red algae genomes that encode dehydrogenases, to use bioinformatic tools to confirm that the proteins encoded are dehydrogenases and to isolate and kinetically purify alcohol or lactate dehydrogenase from red algae species found along the coastline of the Eastern Cape Province. A combination of bioinformatics tools, molecular and biochemical techniques were used to identify, purify, and characterise ADH and LDH enzymes. Bioinformatics analysis revealed two alcohol dehydrogenase genes and two hypothetical genes encoding functional domains similar to D-lactate dehydrogenases from other species. The ADH and LDH-like genes shared low sequence identity at the protein level with medium-chain dehydrogenases/reductases (MDRs) and 2-hydroxy acid dehydrogenases, respectively. These two dehydrogenase genes showed a highly conserved NAD-binding motif (Rossmann-fold) similar to many other NAD-dependent dehydrogenases. The ADH and LDH proteins contained no signal peptides and may be located in the cytoplasm. The phylogenetic tree analysis showed that the two ADH genes belonged to cinnamyl and class III alcohol dehydrogenases, whereas the LDHlike genes were grouped with D-lactate dehydrogenases from other organisms. The ADH and LDH gene family showed cis-acting regulatory elements that are mostly involved in stress response and hormonal response. Structural analysis showed that the dehydrogenases 3D structure predicted models comprise of two domains, namely the substrate binding and the coenzyme binding domains that are rich in beta-strands secondary structure elements. The LDH from red algae was purified approximately 4-fold with a specific activity of 0.044 U/mg. The purified LDH enzyme had a molecular weight of approximately 37kDa. The LDH was active across a broad pH range from 5-9 with a pH optimum observed at 7.5. The LDH ii enzyme in red algae exhibits a temperature optimum of 40 ⁰C and heat stability up to 40 ⁰C. Above 50 °C the LDH activity rapidly decreased showing that the LDH in red algae is not thermostable. The LDH enzyme showed a Km value of 0.8 mM and Vmax of 0.0067 mM.min-1 when using sodium pyruvate as a substrate.
- Full Text:
- Date Issued: 2019
Biological properties and interactions of Kalaharituber pfeilii
- Authors: Krele, Viwe
- Date: 2019
- Subjects: Kalaharituber pfeilii , Pezizales -- South Africa , Desert plants -- South Africa , Truffle culture -- South Africa , Plant biochemical genetics , Enzymes -- Analysis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72257 , vital:30022
- Description: Dessert truffles are seasonal macro fungi and have been identified in several parts of the world including South Africa. The first part of the present study dealt with the assessment of the biologically active compounds of the Kalahari truffles found in the Northern Cape of South Africa. Truffles extracts (methanol, ethanol, aqueous) were investigated for their antimicrobial properties towards Gram-positive and Gram-negative bacteria. The results demonstrated that the truffle extracts tested had no inhibitory effects against the bacterial isolates. The truffle mycelial growth was also noted to be ineffective against the selected bacteria. The bacteria tested in the present study showed some antagonistic effects against the fungus. Cultures of K. pfeilii were also screened for enzyme production including amylase, protease, cellulose, and laccase. Evaluation of the potential of K. pfeilii mycelia to produce these industrially and economically important enzymes demonstrated both amylase and protease activity. However, for laccase and cellulose, no activity was detected. The second part of the present study aimed at optimizing biomass production by K. pfeilii in liquid culture media. FF Microplate containing 95 discreet carbon sources were employed to test for substrate utilization. Blanked readings above 0.1 were regarded as positive for utilization, and 4 substrates were selected as potential substrates and were included in liquid media. Media was evaluated for mycelial biomass production. Of the carbon sources tested sucrose proved to be the most suitable for supporting mycelial growth. The third part of the current study included investigating the diversity of microbial communities colonizing the rhizosheath of Stipagrostis ciliata var. capensis (the host plant of K. pfeilii) and these were identified by means of next-generation sequencing using Illumina Miseq. Bioinformatics tools were utilized in analyzing the data. Actinobacteria were found to be the most dominant bacterial phylum, followed by unclassified bacteria, Proteobacteria, and Acidobacteria. The top 25 sequences were selected and clustered into bacterial OTUs (at 97% threshold) which were assigned into 1 phylum (Actinobacteria), 1 family (Geodermatophilaceae) and 23 genera. This phylum is well known for its secondary metabolites. Streptomyces sp. was the most frequently encountered genus. The results from this study necessitate further investigations with regards to the function and evolution of fungal-bacterial associations. Wheather these bacteria have a contribution towards the truffle development, it is still not confirmed.
- Full Text:
- Date Issued: 2019
- Authors: Krele, Viwe
- Date: 2019
- Subjects: Kalaharituber pfeilii , Pezizales -- South Africa , Desert plants -- South Africa , Truffle culture -- South Africa , Plant biochemical genetics , Enzymes -- Analysis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72257 , vital:30022
- Description: Dessert truffles are seasonal macro fungi and have been identified in several parts of the world including South Africa. The first part of the present study dealt with the assessment of the biologically active compounds of the Kalahari truffles found in the Northern Cape of South Africa. Truffles extracts (methanol, ethanol, aqueous) were investigated for their antimicrobial properties towards Gram-positive and Gram-negative bacteria. The results demonstrated that the truffle extracts tested had no inhibitory effects against the bacterial isolates. The truffle mycelial growth was also noted to be ineffective against the selected bacteria. The bacteria tested in the present study showed some antagonistic effects against the fungus. Cultures of K. pfeilii were also screened for enzyme production including amylase, protease, cellulose, and laccase. Evaluation of the potential of K. pfeilii mycelia to produce these industrially and economically important enzymes demonstrated both amylase and protease activity. However, for laccase and cellulose, no activity was detected. The second part of the present study aimed at optimizing biomass production by K. pfeilii in liquid culture media. FF Microplate containing 95 discreet carbon sources were employed to test for substrate utilization. Blanked readings above 0.1 were regarded as positive for utilization, and 4 substrates were selected as potential substrates and were included in liquid media. Media was evaluated for mycelial biomass production. Of the carbon sources tested sucrose proved to be the most suitable for supporting mycelial growth. The third part of the current study included investigating the diversity of microbial communities colonizing the rhizosheath of Stipagrostis ciliata var. capensis (the host plant of K. pfeilii) and these were identified by means of next-generation sequencing using Illumina Miseq. Bioinformatics tools were utilized in analyzing the data. Actinobacteria were found to be the most dominant bacterial phylum, followed by unclassified bacteria, Proteobacteria, and Acidobacteria. The top 25 sequences were selected and clustered into bacterial OTUs (at 97% threshold) which were assigned into 1 phylum (Actinobacteria), 1 family (Geodermatophilaceae) and 23 genera. This phylum is well known for its secondary metabolites. Streptomyces sp. was the most frequently encountered genus. The results from this study necessitate further investigations with regards to the function and evolution of fungal-bacterial associations. Wheather these bacteria have a contribution towards the truffle development, it is still not confirmed.
- Full Text:
- Date Issued: 2019
Black forest
- Authors: Sachikonye, Tsitsi S A
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/92759 , vital:30745
- Full Text:
- Date Issued: 2019
- Authors: Sachikonye, Tsitsi S A
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/92759 , vital:30745
- Full Text:
- Date Issued: 2019
Block copolymer templates for metal oxide nanostructures
- Authors: Talla, Assane
- Date: 2019
- Subjects: Nanotechnology , Nanostructured materials Metal oxide semiconductors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43889 , vital:37075
- Description: Recent advances in technology have increased the need for fabrication of devices with feature sizes of tens of nanometers, such as ultra-fine filters or membranes, and high density data storage media, to name a few. For this reason, research is now focused on block copolymer nanolithographic processes, particularly the fabrication of nanoscale templates with domains well below 100 nm. Block copolymers have the tendency to self-organise into various structures, such as lamellae, spheres or cylinders on a nanometer scale. Among these possible configurations, the perpendicular cylindrical structure is most desirable, because it can be used for templates or masks for feature development, in particular, oriented wires or rods. In this work, the aim is to create a nano-mask from a di-block copolymer thin film, for zinc oxide nanorods growth. For this purpose poly (styrene-block-methylmethacrylate) (PS-b-PMMA) was investigated as a potential nano-mask. Samples were characterized using X-ray reflectometry to determine the thicknesses of the PS-b-PMMA thin films, while scanning probe microscopy and scanning electron microscopy was used to investigate the surface morphology of the samples. PS-b-PMMA thin films were produced on a random copolymer (poly (styrene-random-methylmethacrylate) (PS-r-PMMA) coated onto a silicon substrate. The PS-r-PMMA permits a non-preferential interaction between the di-block constituents and the substrate. Thermal annealing in vacuum of PS-b-PMMA on PS-r-PMMA led to perpendicular cylinders of PMMA within a PS matrix in the di-block. The typical thicknesses measured for the di-block copolymer films ranged between 33 nm and 37 nm. During this study, a perpendicular orientation of the di-block components was also produced when PS-b-PMMA was spun onto a layer of zinc oxide nanoparticles and thermally annealed in vacuum. It was shown that the ZnO nanoparticles created a corrugated surface on silicon which induced perpendicular cylinders of PMMA within the PS matrix. This was possible for a specific surface roughness parameter and film thickness. In this case, the typical thickness determined for the di-block copolymer ranged between 33 and 35 nm and the surface roughness parameter was 0.07. For the fabrication of a di-block template or PS nano-mask, the vertically oriented PMMA cylindrical nanodomains in the PS matrix were removed by exposing the film to ultraviolet radiation at an adequate dose, followed successively by washing in acetic acid and de-ionized water. It was shown that ultraviolet exposure is necessary to ensure the degradation of PMMA. A subsequent rinse in glacial acetic acid and DI water of the film exposed to ultraviolet, left an array of ordered nanoscopic pores with sizes ranging between 10 nm and 20 nm. Finally, the growth of ZnO nanorods on the di-block template produced on zinc oxide nanoparticles, was attempted using an aqueous solution based-method, namely chemical bath deposition. The rods did not grow inside the nanopores, probably due to poor capillary action. In additional experiments, the di-block template was removed by toluene (a selective solvent for PS) followed by the growth of ZnO rods on the exposed nanoparticle surface. Vertical and well separated ZnO rods formed on this surface, in places where the underlying seed layer had been attacked by the acetic acid treatment during removal of the PMMA. The observed ZnO rod morphology can be used in applications such as solar cell.
- Full Text:
- Date Issued: 2019
- Authors: Talla, Assane
- Date: 2019
- Subjects: Nanotechnology , Nanostructured materials Metal oxide semiconductors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43889 , vital:37075
- Description: Recent advances in technology have increased the need for fabrication of devices with feature sizes of tens of nanometers, such as ultra-fine filters or membranes, and high density data storage media, to name a few. For this reason, research is now focused on block copolymer nanolithographic processes, particularly the fabrication of nanoscale templates with domains well below 100 nm. Block copolymers have the tendency to self-organise into various structures, such as lamellae, spheres or cylinders on a nanometer scale. Among these possible configurations, the perpendicular cylindrical structure is most desirable, because it can be used for templates or masks for feature development, in particular, oriented wires or rods. In this work, the aim is to create a nano-mask from a di-block copolymer thin film, for zinc oxide nanorods growth. For this purpose poly (styrene-block-methylmethacrylate) (PS-b-PMMA) was investigated as a potential nano-mask. Samples were characterized using X-ray reflectometry to determine the thicknesses of the PS-b-PMMA thin films, while scanning probe microscopy and scanning electron microscopy was used to investigate the surface morphology of the samples. PS-b-PMMA thin films were produced on a random copolymer (poly (styrene-random-methylmethacrylate) (PS-r-PMMA) coated onto a silicon substrate. The PS-r-PMMA permits a non-preferential interaction between the di-block constituents and the substrate. Thermal annealing in vacuum of PS-b-PMMA on PS-r-PMMA led to perpendicular cylinders of PMMA within a PS matrix in the di-block. The typical thicknesses measured for the di-block copolymer films ranged between 33 nm and 37 nm. During this study, a perpendicular orientation of the di-block components was also produced when PS-b-PMMA was spun onto a layer of zinc oxide nanoparticles and thermally annealed in vacuum. It was shown that the ZnO nanoparticles created a corrugated surface on silicon which induced perpendicular cylinders of PMMA within the PS matrix. This was possible for a specific surface roughness parameter and film thickness. In this case, the typical thickness determined for the di-block copolymer ranged between 33 and 35 nm and the surface roughness parameter was 0.07. For the fabrication of a di-block template or PS nano-mask, the vertically oriented PMMA cylindrical nanodomains in the PS matrix were removed by exposing the film to ultraviolet radiation at an adequate dose, followed successively by washing in acetic acid and de-ionized water. It was shown that ultraviolet exposure is necessary to ensure the degradation of PMMA. A subsequent rinse in glacial acetic acid and DI water of the film exposed to ultraviolet, left an array of ordered nanoscopic pores with sizes ranging between 10 nm and 20 nm. Finally, the growth of ZnO nanorods on the di-block template produced on zinc oxide nanoparticles, was attempted using an aqueous solution based-method, namely chemical bath deposition. The rods did not grow inside the nanopores, probably due to poor capillary action. In additional experiments, the di-block template was removed by toluene (a selective solvent for PS) followed by the growth of ZnO rods on the exposed nanoparticle surface. Vertical and well separated ZnO rods formed on this surface, in places where the underlying seed layer had been attacked by the acetic acid treatment during removal of the PMMA. The observed ZnO rod morphology can be used in applications such as solar cell.
- Full Text:
- Date Issued: 2019