An investigation of the Social and Structural basis for the emergence of social movements in Zimbabwe. A Comparative study of the Combined Harare Residents Association and Zimbabwe National Liberation War Veterans Association
- Authors: Chaitezvi, Trevour
- Date: 2019
- Subjects: Social movements
- Language: English
- Type: Thesis , Masters , MSoc. Sci (Sociology)
- Identifier: http://hdl.handle.net/10353/17564 , vital:41091
- Description: The emergence of urban social movements in the Zimbabwean context is mainly attributed to the political economic crisis, which resulted in the decline of municipal services and other socioeconomic rights central to the ordinary people. In the rural areas many scholars have alluded to the failure of the state to institute a radical transformation of the rural areas as the reason for the emergence of land movement and the subsequent land revolutions that followed in the early 2000s. Within this context, this study sought to investigate the social and structural basis for the emergence of social movements in Zimbabwe. The argument of this study hinges on the central premise of the political opportunity structure approach, which states that the emergence and success of social movements depends on certain political opportunities within the political environment. Building upon the guidance of the qualitative paradigm, whose method of investigation includes in-depth interviews and focus group discussions, the findings illustrate that the emergence of rural social movements in Zimbabwe was mainly to address the land question; such initiatives were to be done through fighting imperialism that hinges upon neo-liberal policies. In addition, one of the objectives for the emergence of rural social movements was to complete the objective of the liberation war, which was to give back the land to the indigenous black people. The tactics of the rural social movement included engaging the state and confronting it in other instances. Further, illegal land occupations were also one of the tactics of this movement. Ideologically, the movement used a Pan-African ideology to confront neo-colonization. On the other hand, the findings of the study illustrate that the emergence of urban social movements was mainly to provide a platform for the marginalized people to voice their discontent of the decline of service delivery in the urban context. Since most of these aspects were linked to the broader economic crisis facing the country, urban social movements also intended to initiate a political transition. The tactics of urban social movements included disruption, the establishment of networks with other social movements and the use of media, while constructing their ideology within the human rights framewo
- Full Text:
- Date Issued: 2019
- Authors: Chaitezvi, Trevour
- Date: 2019
- Subjects: Social movements
- Language: English
- Type: Thesis , Masters , MSoc. Sci (Sociology)
- Identifier: http://hdl.handle.net/10353/17564 , vital:41091
- Description: The emergence of urban social movements in the Zimbabwean context is mainly attributed to the political economic crisis, which resulted in the decline of municipal services and other socioeconomic rights central to the ordinary people. In the rural areas many scholars have alluded to the failure of the state to institute a radical transformation of the rural areas as the reason for the emergence of land movement and the subsequent land revolutions that followed in the early 2000s. Within this context, this study sought to investigate the social and structural basis for the emergence of social movements in Zimbabwe. The argument of this study hinges on the central premise of the political opportunity structure approach, which states that the emergence and success of social movements depends on certain political opportunities within the political environment. Building upon the guidance of the qualitative paradigm, whose method of investigation includes in-depth interviews and focus group discussions, the findings illustrate that the emergence of rural social movements in Zimbabwe was mainly to address the land question; such initiatives were to be done through fighting imperialism that hinges upon neo-liberal policies. In addition, one of the objectives for the emergence of rural social movements was to complete the objective of the liberation war, which was to give back the land to the indigenous black people. The tactics of the rural social movement included engaging the state and confronting it in other instances. Further, illegal land occupations were also one of the tactics of this movement. Ideologically, the movement used a Pan-African ideology to confront neo-colonization. On the other hand, the findings of the study illustrate that the emergence of urban social movements was mainly to provide a platform for the marginalized people to voice their discontent of the decline of service delivery in the urban context. Since most of these aspects were linked to the broader economic crisis facing the country, urban social movements also intended to initiate a political transition. The tactics of urban social movements included disruption, the establishment of networks with other social movements and the use of media, while constructing their ideology within the human rights framewo
- Full Text:
- Date Issued: 2019
An investigation of the teaching of writing in Grade-9 English first-language classrooms: a case study of a selected government school in Namibia
- Martins, Simone Alexandra Domingues
- Authors: Martins, Simone Alexandra Domingues
- Date: 2019
- Subjects: English language -- Rhetoric -- Study and teaching -- Namibia , English language -- Study and teaching (Secondary) -- Namibia , English language == Composition and exercises -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/92280 , vital:30699
- Description: The pedagogical practice choices teachers make when teaching writing in Grade-9 English first- language classrooms, as well as the extent to which these pedagogical practices appear to enable or constrain learners’ acquisition of writing skills as per grade-specific curricular expectations, are the focus of the study. It draws from Bernstein’s (1971) curriculum and society theory, as well as genre theory. Located within the qualitative case study approach, it is designed to investigate the reasons for Grade-9 English first-language learners’ underperformance in Paper 2, the composition component of the Namibian external examinations. Drawing from the interpretivist paradigm, the study uses one-on-one interviews, semi-structured classroom observations, as well as documentary evidence of the Namibian English first-language syllabus and examples of learners’ written work, to generate data. The research site and study participants were purposefully selected. The study involves two Grade-9 English first-language teachers and classrooms at one Namibian High School, and took place from the second to the third terms of 2017.
- Full Text:
- Date Issued: 2019
- Authors: Martins, Simone Alexandra Domingues
- Date: 2019
- Subjects: English language -- Rhetoric -- Study and teaching -- Namibia , English language -- Study and teaching (Secondary) -- Namibia , English language == Composition and exercises -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/92280 , vital:30699
- Description: The pedagogical practice choices teachers make when teaching writing in Grade-9 English first- language classrooms, as well as the extent to which these pedagogical practices appear to enable or constrain learners’ acquisition of writing skills as per grade-specific curricular expectations, are the focus of the study. It draws from Bernstein’s (1971) curriculum and society theory, as well as genre theory. Located within the qualitative case study approach, it is designed to investigate the reasons for Grade-9 English first-language learners’ underperformance in Paper 2, the composition component of the Namibian external examinations. Drawing from the interpretivist paradigm, the study uses one-on-one interviews, semi-structured classroom observations, as well as documentary evidence of the Namibian English first-language syllabus and examples of learners’ written work, to generate data. The research site and study participants were purposefully selected. The study involves two Grade-9 English first-language teachers and classrooms at one Namibian High School, and took place from the second to the third terms of 2017.
- Full Text:
- Date Issued: 2019
An investigation ofthe effectiveness of using analogies to develop a robust understanding of direct current (DC) electric circuits in first-year university students
- Authors: Bacela, Mpathi Collin
- Date: 2019
- Subjects: Physics -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/42443 , vital:36657
- Description: The effectiveness of using a teaching strategy, based on analogies for direct current electric circuits, to attempt to address first-year underprepared university students was investigated. The study consisted of 53 participants drawn from the Faculty of Health Sciences at Nelson Mandela University. A quantitative research design was adopted using the “Determining and Interpreting Resistive Electric Circuits Concepts Test” (DIRECT) version 1.2 as a research instrument. The DIRECT is a 29-item multiple-choice test with only one correct answer in each question. The DIRECT was modified to further probe students’ confidence levels in their answers. The instrument served as a pre-test prior to the start of the formal lessons on direct current electric circuits. At the end of a five-week treatment period, the same instrument was administered to all participants as a post-test. The statistical analysis and interpretation of the preand post-test data were conducted using Software Package for Social Sciences (SPSS) version 23 and STATISTICA version 12. In answering the main research question (How can a misconception-based module, using analogies,positively influence(or not)academically under-prepared first-year non-major Physics students’ conceptual understanding of direct current(DC)electricalcircuits?)and sub-questions thereof, the students’ mean scores between the pre-and posttest were calculate and compared using t-test at a significant level of 0.05. The results revealed a statistically significant difference between the preand post-test mean scores. The pre-test mean score was 22.24 with a standard deviation of 8.07. The post-test mean score was 38.68 with a standard deviation of 13.93. The mean score difference between the post-test and pre-test was 16.44 with a standard deviation of 13.82 at p-value less than 0.05. The results from the pre-test suggest that students held very strong alternative conceptions on direct current electric circuits. The post-test results also revealed that some alternative conceptions were still held onto after the intervention. There wasno statistical significant difference found between the students’ correct answers and their confidence levels. The quantitative analysis of the results suggested that there is a positive change between the post-testmean score and pre-test mean score and this change is statistically significant (p < 0.05). The results showed sufficient evidence to conclude that analogies-based teaching strategy was a vieffective means of reducing the number of alternative conceptions the students held about direct current electric circuits. The study recommended the need to ascertain out what the students felt about the improvement of their understanding of direct current electric circuits concepts. The study suggested a qualitative research methodology as an area for future research.
- Full Text:
- Date Issued: 2019
- Authors: Bacela, Mpathi Collin
- Date: 2019
- Subjects: Physics -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/42443 , vital:36657
- Description: The effectiveness of using a teaching strategy, based on analogies for direct current electric circuits, to attempt to address first-year underprepared university students was investigated. The study consisted of 53 participants drawn from the Faculty of Health Sciences at Nelson Mandela University. A quantitative research design was adopted using the “Determining and Interpreting Resistive Electric Circuits Concepts Test” (DIRECT) version 1.2 as a research instrument. The DIRECT is a 29-item multiple-choice test with only one correct answer in each question. The DIRECT was modified to further probe students’ confidence levels in their answers. The instrument served as a pre-test prior to the start of the formal lessons on direct current electric circuits. At the end of a five-week treatment period, the same instrument was administered to all participants as a post-test. The statistical analysis and interpretation of the preand post-test data were conducted using Software Package for Social Sciences (SPSS) version 23 and STATISTICA version 12. In answering the main research question (How can a misconception-based module, using analogies,positively influence(or not)academically under-prepared first-year non-major Physics students’ conceptual understanding of direct current(DC)electricalcircuits?)and sub-questions thereof, the students’ mean scores between the pre-and posttest were calculate and compared using t-test at a significant level of 0.05. The results revealed a statistically significant difference between the preand post-test mean scores. The pre-test mean score was 22.24 with a standard deviation of 8.07. The post-test mean score was 38.68 with a standard deviation of 13.93. The mean score difference between the post-test and pre-test was 16.44 with a standard deviation of 13.82 at p-value less than 0.05. The results from the pre-test suggest that students held very strong alternative conceptions on direct current electric circuits. The post-test results also revealed that some alternative conceptions were still held onto after the intervention. There wasno statistical significant difference found between the students’ correct answers and their confidence levels. The quantitative analysis of the results suggested that there is a positive change between the post-testmean score and pre-test mean score and this change is statistically significant (p < 0.05). The results showed sufficient evidence to conclude that analogies-based teaching strategy was a vieffective means of reducing the number of alternative conceptions the students held about direct current electric circuits. The study recommended the need to ascertain out what the students felt about the improvement of their understanding of direct current electric circuits concepts. The study suggested a qualitative research methodology as an area for future research.
- Full Text:
- Date Issued: 2019
Analyses of Retail and Transport Geography of Liquefied Petroleum Products in Ibadan metropolis, Nigeria
- Authors: Ajayi, Adeyinka Peter
- Date: 2019
- Subjects: Petroleum products
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/19065 , vital:40090
- Description: This study analyzed the effects that spatial arrangement of petroleum products retail outlets and the supply chain management techniques employed for products distribution (for both intra city and intercity shipments) have on the retailing dynamism of petroleum products within built environment and peripherals of Ibadan metropolis over the years. Specifically, the study investigated the differentials in the spatial configurations of petroleum products retail outlets between the core and periurban zones of the metropolis. An attempt was made to determine the explanatory variables that influence the spatial distributional decisions of petroleum products retail outlets in the metropolis. The study equally examined how the supply chain management (SCM) techniques by the different categories of the retail outlet owners influence the efficient and cost effective distribution of petroleum products. Lastly an attempt was made to analyze the relationship between the socio-economic attributes of the haulers and the achievement of compliance to the HSE stipulations guiding the conveyance of petroleum products. The theoretical underpinnings for the research were a derivative of the amalgamation of normative and psychological theories from geography, psychology, SCM and retailing science. Specifically, Expectation Disconfirmation Theory (EDT), Distributive Justice, Central Place Theory (CPT) Theories of Urban Impact (TUI) and Theory of Constraint (ToC) were the theories utilized in the study. For the achievement of the first objective which was to investigate the possible differential in the compliance rate between spatial pattern of fuel retail outlets in the core and peripheral zones of Ibadan metropolis, the first hypothesis of the study (which examined if there was no significant difference in the rate of compliance to the planning authority stipulations guiding the location pattern of petroleum product retail outlets between those located in the built up and xxiv peripheral zones of the city), was tested through the use of buffering and proximity analyses in the ArcMap environment of ArcGIS 10.1, while inferential statistical tool of an independent-samples t-test was conducted to compare the rate of compliance to the stipulations guiding the locations of these outlets in both the core and the peripheral zones. The result from the GIS analysis indicated that 33 (15.56%) out of the 220 outlets in the core zone of the metropolis complied with the planning stipulations guiding the location of fuel retail outlets. For the peripheral zone, out of the 220 fuel retail outlets 24 (10.90%) complied with the stipulations. The result from the t- test which was employed to test the hypothesis indicated that no significant difference existed in the rate of compliance t (263) =-2.66, p = 0.08 between fuel retail outlets in the core zone (M=3.9, SD=1.4) and peripheral zone (M=4.5, SD=1.79). The alternate hypothesis which stated that ―no significant difference existed in the compliance rate between fuel retail outlets located in the two zones‖ is accepted. For the achievement of the second objective of the study which was to analyze the factors which determine the location of fuel retail outlets both in the core and peripheral zones of Ibadan metropolis. All the managers/owners of the 432 fuel retail outlets in the metropolis were sampled out of which 256 questionnaires were retrieved for the purpose of this analysis. The breakdown of the socio-economic characteristics of the sampled respondents showed that the gender distribution showed that 194 (75.78%) of the respondents were males, while 64 (24.22 %) were females. The average age of the sampled population was 33.70 years. The mixed method was employed for the achievement of the second objective of this study. Logistic Regression Model (LRM) was employed to test the hypothesis and the result revealed that the inclusion of the independent variables in the model increased the overall level of it accuracy. The overall significance revealed that the Model Chi- xxv Square, derived from the likelihood fitted is also accurate (X2 = 43.47, df=5, p>.05). The model chi-square value of 43.47 (approximately 44% ) was significant. Thus, the indication is that the model has a good fit in predicting the possibility of a fuel retail outlet being located in the core or peripheral zone of the metropolis as determined by the explanatory variables (the independent variables accounted for about 44% of possible factors which determined whether a fuel retail outlets is located either within the core or peripheral zones of the metropolis. The remaining 56% are factors not considered in the study). The result gotten from the in depth interview sessions corroborated the findings from the tested hypothesis. The third objective was to examine the effects which the supply chain technique employed (either vertically integrated model or third-party arrangement) has on the achievement of efficient and effective distribution of the products. In order to achieve this objective, all the 389 registered members of Petroleum Tanker Drivers (PTD) association who are members of the PTD in the metropolis were sampled, 265 (around 70%) of the distributed questionnaires were retrieved and used for the analysis. In depth interview sessions were also conducted with three different managers of the three major conglomerates in the downstream sector of the Nigerian petroleum sector. The result of one-way between subjects (ANOVA) which was conducted to compare differences in the management and performances of haulage services outsourced to the 3PLS and those run under VIM showed that there was a significant effect of ownership type on management performance (F (2,262) = 60.26, p<.05). The null hypothesis was therefore rejected while the alternate hypothesis was accepted. The findings from the interview sessions posted similar results. The fourth and final objective was to analyze the effect that the socio-economic attributes of the participants (haulers and managers of retail outlets) involved in the distribution of xxvi petroleum products has on the safe, efficient and cost-effective distribution of product and this was done through the use of descriptive statistics, inferential statistics and incisive analysis of the interview sessions. A total number of 265 (70%) out of the 389 registered members of Petroleum Tanker Driver Association (PTDA) participated in the study. Multiple regression analysis (MRA) was used to test this hypothesis. The result from the statistical analysis show that the use of stimulant, work condition, marital status and educational attainment/literacy level have joint influence on compliance (R2 = 0.31, F (4,260) = 29.72, p<.05). On the basis of the foregoing, the hypothesis is thus accepted. The result from the interview sessions confirmed the existence of strong relationship between the explanatory variables and the hypothetical dependant variable. The study recommended a review of the planning processes guiding the establishment of fuel retail outlets. The study also advocated that retailers should endeavour to have stronger control over the supply chain of their products this could done by investing more in VIM rather than outsourcing such functions to 3PLs. This will help in better business performances. Government agencies in charge of monitoring drug abuse among haulers are advised to be more proactive by the duo of prevention and punishment strategies. This should include advocacy campaign against drug abuse. Different ranges of punishments should also be meted out for individual haulers found culpable.
- Full Text:
- Date Issued: 2019
- Authors: Ajayi, Adeyinka Peter
- Date: 2019
- Subjects: Petroleum products
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/19065 , vital:40090
- Description: This study analyzed the effects that spatial arrangement of petroleum products retail outlets and the supply chain management techniques employed for products distribution (for both intra city and intercity shipments) have on the retailing dynamism of petroleum products within built environment and peripherals of Ibadan metropolis over the years. Specifically, the study investigated the differentials in the spatial configurations of petroleum products retail outlets between the core and periurban zones of the metropolis. An attempt was made to determine the explanatory variables that influence the spatial distributional decisions of petroleum products retail outlets in the metropolis. The study equally examined how the supply chain management (SCM) techniques by the different categories of the retail outlet owners influence the efficient and cost effective distribution of petroleum products. Lastly an attempt was made to analyze the relationship between the socio-economic attributes of the haulers and the achievement of compliance to the HSE stipulations guiding the conveyance of petroleum products. The theoretical underpinnings for the research were a derivative of the amalgamation of normative and psychological theories from geography, psychology, SCM and retailing science. Specifically, Expectation Disconfirmation Theory (EDT), Distributive Justice, Central Place Theory (CPT) Theories of Urban Impact (TUI) and Theory of Constraint (ToC) were the theories utilized in the study. For the achievement of the first objective which was to investigate the possible differential in the compliance rate between spatial pattern of fuel retail outlets in the core and peripheral zones of Ibadan metropolis, the first hypothesis of the study (which examined if there was no significant difference in the rate of compliance to the planning authority stipulations guiding the location pattern of petroleum product retail outlets between those located in the built up and xxiv peripheral zones of the city), was tested through the use of buffering and proximity analyses in the ArcMap environment of ArcGIS 10.1, while inferential statistical tool of an independent-samples t-test was conducted to compare the rate of compliance to the stipulations guiding the locations of these outlets in both the core and the peripheral zones. The result from the GIS analysis indicated that 33 (15.56%) out of the 220 outlets in the core zone of the metropolis complied with the planning stipulations guiding the location of fuel retail outlets. For the peripheral zone, out of the 220 fuel retail outlets 24 (10.90%) complied with the stipulations. The result from the t- test which was employed to test the hypothesis indicated that no significant difference existed in the rate of compliance t (263) =-2.66, p = 0.08 between fuel retail outlets in the core zone (M=3.9, SD=1.4) and peripheral zone (M=4.5, SD=1.79). The alternate hypothesis which stated that ―no significant difference existed in the compliance rate between fuel retail outlets located in the two zones‖ is accepted. For the achievement of the second objective of the study which was to analyze the factors which determine the location of fuel retail outlets both in the core and peripheral zones of Ibadan metropolis. All the managers/owners of the 432 fuel retail outlets in the metropolis were sampled out of which 256 questionnaires were retrieved for the purpose of this analysis. The breakdown of the socio-economic characteristics of the sampled respondents showed that the gender distribution showed that 194 (75.78%) of the respondents were males, while 64 (24.22 %) were females. The average age of the sampled population was 33.70 years. The mixed method was employed for the achievement of the second objective of this study. Logistic Regression Model (LRM) was employed to test the hypothesis and the result revealed that the inclusion of the independent variables in the model increased the overall level of it accuracy. The overall significance revealed that the Model Chi- xxv Square, derived from the likelihood fitted is also accurate (X2 = 43.47, df=5, p>.05). The model chi-square value of 43.47 (approximately 44% ) was significant. Thus, the indication is that the model has a good fit in predicting the possibility of a fuel retail outlet being located in the core or peripheral zone of the metropolis as determined by the explanatory variables (the independent variables accounted for about 44% of possible factors which determined whether a fuel retail outlets is located either within the core or peripheral zones of the metropolis. The remaining 56% are factors not considered in the study). The result gotten from the in depth interview sessions corroborated the findings from the tested hypothesis. The third objective was to examine the effects which the supply chain technique employed (either vertically integrated model or third-party arrangement) has on the achievement of efficient and effective distribution of the products. In order to achieve this objective, all the 389 registered members of Petroleum Tanker Drivers (PTD) association who are members of the PTD in the metropolis were sampled, 265 (around 70%) of the distributed questionnaires were retrieved and used for the analysis. In depth interview sessions were also conducted with three different managers of the three major conglomerates in the downstream sector of the Nigerian petroleum sector. The result of one-way between subjects (ANOVA) which was conducted to compare differences in the management and performances of haulage services outsourced to the 3PLS and those run under VIM showed that there was a significant effect of ownership type on management performance (F (2,262) = 60.26, p<.05). The null hypothesis was therefore rejected while the alternate hypothesis was accepted. The findings from the interview sessions posted similar results. The fourth and final objective was to analyze the effect that the socio-economic attributes of the participants (haulers and managers of retail outlets) involved in the distribution of xxvi petroleum products has on the safe, efficient and cost-effective distribution of product and this was done through the use of descriptive statistics, inferential statistics and incisive analysis of the interview sessions. A total number of 265 (70%) out of the 389 registered members of Petroleum Tanker Driver Association (PTDA) participated in the study. Multiple regression analysis (MRA) was used to test this hypothesis. The result from the statistical analysis show that the use of stimulant, work condition, marital status and educational attainment/literacy level have joint influence on compliance (R2 = 0.31, F (4,260) = 29.72, p<.05). On the basis of the foregoing, the hypothesis is thus accepted. The result from the interview sessions confirmed the existence of strong relationship between the explanatory variables and the hypothetical dependant variable. The study recommended a review of the planning processes guiding the establishment of fuel retail outlets. The study also advocated that retailers should endeavour to have stronger control over the supply chain of their products this could done by investing more in VIM rather than outsourcing such functions to 3PLs. This will help in better business performances. Government agencies in charge of monitoring drug abuse among haulers are advised to be more proactive by the duo of prevention and punishment strategies. This should include advocacy campaign against drug abuse. Different ranges of punishments should also be meted out for individual haulers found culpable.
- Full Text:
- Date Issued: 2019
Analysis of monitoring and evaluation as an internal control measure for supply chain management: a case for department of public works and transport
- Authors: Mfeketo, Lunga
- Date: 2019
- Subjects: Business logistics , Industrial procurement Inventory control Physical distribution of goods
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/41327 , vital:36445
- Description: The National Treasury Regulations (2009) require all government departments to exercise transparency, openness and fairness in the procurement of all goods and services. The aim of this study was to analyse and determine the use of Monitoring and Evaluation (M&E) as an internal control measure in the supply chain management (SCM) process by the Department of Roads and Public Works (DRT), Sarah Baartman District Center. Poor internal controls, in relation to SCM regulatory framework compliance, remains a key challenge for the DPWT which led to negative performance information in the audit findings (Auditor-General, 2016/17). SCM falls within the finance management pillar which is one of the most important governance areas in public resource management. The study presents the place and nature of the public SCM environment, relevant theories and legislative frameworks towards an efficient and transparent SCM value chain. 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”. The study adopted a qualitative documentary analysis research approach. A core finding of the study suggested that the provincial sphere of government needed to develop a participatory provincial government strategy for provincial development. A key recommendation that has been forwarded, suggests that the government needs to strengthen the policy on provincial management in order to facilitate sustainable economic growth and thereby promote social welfare gains.
- Full Text:
- Date Issued: 2019
- Authors: Mfeketo, Lunga
- Date: 2019
- Subjects: Business logistics , Industrial procurement Inventory control Physical distribution of goods
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/41327 , vital:36445
- Description: The National Treasury Regulations (2009) require all government departments to exercise transparency, openness and fairness in the procurement of all goods and services. The aim of this study was to analyse and determine the use of Monitoring and Evaluation (M&E) as an internal control measure in the supply chain management (SCM) process by the Department of Roads and Public Works (DRT), Sarah Baartman District Center. Poor internal controls, in relation to SCM regulatory framework compliance, remains a key challenge for the DPWT which led to negative performance information in the audit findings (Auditor-General, 2016/17). SCM falls within the finance management pillar which is one of the most important governance areas in public resource management. The study presents the place and nature of the public SCM environment, relevant theories and legislative frameworks towards an efficient and transparent SCM value chain. 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”. The study adopted a qualitative documentary analysis research approach. A core finding of the study suggested that the provincial sphere of government needed to develop a participatory provincial government strategy for provincial development. A key recommendation that has been forwarded, suggests that the government needs to strengthen the policy on provincial management in order to facilitate sustainable economic growth and thereby promote social welfare gains.
- Full Text:
- Date Issued: 2019
Analysis of strategies for an effective Supply Chain Management Policy Framework in the Department of Economic Development, Environmental Affairs and Tourism in the Eastern Cape, South Africa.
- Authors: Balman, Vuyani Brian
- Date: 2019
- Subjects: Industrial procurement -- Management Business logistics
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/36299 , vital:33918
- Description: After the 1994 general elections, the government realised the importance of efficient and effective financial management and public sector procurement for the rebuilding of South Africa. This was done by embarking on a major review of its financial and supply chain management systems. The financial and supply chain management systems operate in an ever-changing environment, and that requires that these systems are fit for purpose. Supply Chain Management is one of the cornerstones for the performance of any organisation or company. Section 217 (3) of the Constitution of the Republic of South Africa requires organs of state irrespective of whether they are at National, Provincial or Local government level to apply a procurement system which is fair, equitable, transparent, competitive and cost-effective when contracting for goods and services. The Constitution also attempts to protect and advance persons disadvantaged by unfair discrimination. Supply Chain Management has met an ever-increasing interest over the past decade. This interest comes from within the industry due to the huge amounts involved in procurement and the supply chain value creation. Every society strives to be in a state where every need is available and every citizen has what he/she requires to be able to leave a fulfilled life. In order to meet the needs of societies, member of the society carry out economic activities. The public procurement practice and systems have been acclaimed, based on empirical evidence, as the best means of guaranteeing the provision of public goods to the Citizens and public expenditure management.
- Full Text: false
- Date Issued: 2019
- Authors: Balman, Vuyani Brian
- Date: 2019
- Subjects: Industrial procurement -- Management Business logistics
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/36299 , vital:33918
- Description: After the 1994 general elections, the government realised the importance of efficient and effective financial management and public sector procurement for the rebuilding of South Africa. This was done by embarking on a major review of its financial and supply chain management systems. The financial and supply chain management systems operate in an ever-changing environment, and that requires that these systems are fit for purpose. Supply Chain Management is one of the cornerstones for the performance of any organisation or company. Section 217 (3) of the Constitution of the Republic of South Africa requires organs of state irrespective of whether they are at National, Provincial or Local government level to apply a procurement system which is fair, equitable, transparent, competitive and cost-effective when contracting for goods and services. The Constitution also attempts to protect and advance persons disadvantaged by unfair discrimination. Supply Chain Management has met an ever-increasing interest over the past decade. This interest comes from within the industry due to the huge amounts involved in procurement and the supply chain value creation. Every society strives to be in a state where every need is available and every citizen has what he/she requires to be able to leave a fulfilled life. In order to meet the needs of societies, member of the society carry out economic activities. The public procurement practice and systems have been acclaimed, based on empirical evidence, as the best means of guaranteeing the provision of public goods to the Citizens and public expenditure management.
- Full Text: false
- Date Issued: 2019
Analysis of the pre- to post- apartheid language in education policies: an investigation for multilingualism
- Authors: Zumani, Nobesutu Faith
- Date: 2019
- Subjects: Multilingual education -- South Africa , Native language and education -- South Africa Language policy -- South Africa African languages -- Social aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/44235 , vital:37140
- Description: The 1997 language policy in basic education promotes multilingualism in basic, education where there is under-utilisation of African languages. The main aim of this study is to investigate the reason for the under-utilisation of African languages in basic education. Transitional bilingual education is practised (TBE) instead of developmental maintenance bilingual education (MBE). The pre and post-apartheid language- in-education policies, including the Constitution, were collected, analysed and interpreted to find out why these languages are not used for education. It was discovered that the legacy of the previous policies has had an influence on the present policy. Also, the escape clauses on the present policy, such as “practicably reasonable,” and “choose,” have an impact on non-implementation of the post-apartheid language policy. The researcher recommends the development of an implementation plan and the revision of powers for SGBs to choose languages for their schools.
- Full Text:
- Date Issued: 2019
- Authors: Zumani, Nobesutu Faith
- Date: 2019
- Subjects: Multilingual education -- South Africa , Native language and education -- South Africa Language policy -- South Africa African languages -- Social aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/44235 , vital:37140
- Description: The 1997 language policy in basic education promotes multilingualism in basic, education where there is under-utilisation of African languages. The main aim of this study is to investigate the reason for the under-utilisation of African languages in basic education. Transitional bilingual education is practised (TBE) instead of developmental maintenance bilingual education (MBE). The pre and post-apartheid language- in-education policies, including the Constitution, were collected, analysed and interpreted to find out why these languages are not used for education. It was discovered that the legacy of the previous policies has had an influence on the present policy. Also, the escape clauses on the present policy, such as “practicably reasonable,” and “choose,” have an impact on non-implementation of the post-apartheid language policy. The researcher recommends the development of an implementation plan and the revision of powers for SGBs to choose languages for their schools.
- Full Text:
- Date Issued: 2019
Analyzing the Anthropogenic Allee Effect in cycad (Encephalartos species) populations in South Africa: an evaluation of illegal trade and conservation policy
- Authors: Earle, Sasha
- Date: 2019
- Subjects: Allee effect , Cycads -- Conservation -- South Africa , Botany, Economic -- South Africa , Rare plants -- South Africa , Endangered plants -- South Africa , Wild plant trade -- Law and legislation -- South Africa
- Language: English
- Type: text , Thesis , Masters , Mcom
- Identifier: http://hdl.handle.net/10962/95565 , vital:31171
- Description: South Africa is a country known for rich biodiversity and ecosystems across the land and seascape. South Africa is one of the global hotspots for cycad diversity. Cycads are known to be the world’s most threatened plant species; declining in South Africa at a rapid pace, with threat of extinction in the wild. The main factor being harvesting from the wild for private collections. Rare cycad species’ are especially sought after by collectors. Economic theory assumes that the exploitation of a species is unlikely to result in extinction due to the increasing costs of finding the last few individuals of a species. However, the theory of the Anthropogenic Allee Effect (AAE) suggests that if consumers place a disproportionate value on a rare species’, a cycle may result whereby increased exploitation decreases population size, increasing the value of the species and, consequently, leading to its extinction in the wild. This hypothesis was tested for 37 Encephalartos species using data collected on wild populations, auction prices and the IUCN Red List status for the year 2010. It was hypothesised that an AAE was present within Encephalartos species, as three species have already gone extinct in the wild. The price per centimetre was positively correlated to the rarity of the species and the price per centimetre was negatively correlated to the wild population size. The results suggest a trend of an AAE for the year 2010. Adequate conservation policies are needed to reduce the effects of demand on illegal harvesting and prevent extinction in the wild. The effect of rarity needs to be taken into account to ensure successfulness of such policies. The most recent conservation policy implemented to protect cycads in South Africa is the Strategy and Action for the Management of Cycads in South Africa, which was introduced in 2016. The successfulness of this policy cannot, however, be analysed due to a lack of census data following its implementation.
- Full Text:
- Date Issued: 2019
- Authors: Earle, Sasha
- Date: 2019
- Subjects: Allee effect , Cycads -- Conservation -- South Africa , Botany, Economic -- South Africa , Rare plants -- South Africa , Endangered plants -- South Africa , Wild plant trade -- Law and legislation -- South Africa
- Language: English
- Type: text , Thesis , Masters , Mcom
- Identifier: http://hdl.handle.net/10962/95565 , vital:31171
- Description: South Africa is a country known for rich biodiversity and ecosystems across the land and seascape. South Africa is one of the global hotspots for cycad diversity. Cycads are known to be the world’s most threatened plant species; declining in South Africa at a rapid pace, with threat of extinction in the wild. The main factor being harvesting from the wild for private collections. Rare cycad species’ are especially sought after by collectors. Economic theory assumes that the exploitation of a species is unlikely to result in extinction due to the increasing costs of finding the last few individuals of a species. However, the theory of the Anthropogenic Allee Effect (AAE) suggests that if consumers place a disproportionate value on a rare species’, a cycle may result whereby increased exploitation decreases population size, increasing the value of the species and, consequently, leading to its extinction in the wild. This hypothesis was tested for 37 Encephalartos species using data collected on wild populations, auction prices and the IUCN Red List status for the year 2010. It was hypothesised that an AAE was present within Encephalartos species, as three species have already gone extinct in the wild. The price per centimetre was positively correlated to the rarity of the species and the price per centimetre was negatively correlated to the wild population size. The results suggest a trend of an AAE for the year 2010. Adequate conservation policies are needed to reduce the effects of demand on illegal harvesting and prevent extinction in the wild. The effect of rarity needs to be taken into account to ensure successfulness of such policies. The most recent conservation policy implemented to protect cycads in South Africa is the Strategy and Action for the Management of Cycads in South Africa, which was introduced in 2016. The successfulness of this policy cannot, however, be analysed due to a lack of census data following its implementation.
- Full Text:
- Date Issued: 2019
Another world is possible: the socialist mural in Luanda as Visual Anticipation of a New Socialist Society. We travel the SpaceWay-Black Imagination, Fragments and Diffractions
- Authors: Siegert, Nadine
- Date: 2019
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/146309 , vital:38514 , ISBN 9783960915300
- Description: Book abstract. From the visual politics of the FRELIMO-liberation script in Mozambique via the brooms and spoons of Le Balai Citoyen in Burkina Faso, to the updating of images from past revolutions on Twitter and Facebook, often in the diaspora – images play a key role in the envisioning of futures and social utopia. And more than that: Revolutions, understood as moments of radical social and cultural change, are driven by images, as empirical investigations on- and offline show. But what actually constitutes the 'seismographic power' of images, and the sustainability of icons from past ruptures in terms of radicalism, such as the portraits of Burkina Faso's and Mozambiques first presidents' Thomas Sankara and Samora Machel?.
- Full Text:
- Date Issued: 2019
- Authors: Siegert, Nadine
- Date: 2019
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/146309 , vital:38514 , ISBN 9783960915300
- Description: Book abstract. From the visual politics of the FRELIMO-liberation script in Mozambique via the brooms and spoons of Le Balai Citoyen in Burkina Faso, to the updating of images from past revolutions on Twitter and Facebook, often in the diaspora – images play a key role in the envisioning of futures and social utopia. And more than that: Revolutions, understood as moments of radical social and cultural change, are driven by images, as empirical investigations on- and offline show. But what actually constitutes the 'seismographic power' of images, and the sustainability of icons from past ruptures in terms of radicalism, such as the portraits of Burkina Faso's and Mozambiques first presidents' Thomas Sankara and Samora Machel?.
- Full Text:
- Date Issued: 2019
Antecedents and influence of the union-management relationship on employee relationships in the automotive, component and metal industries in the Nelson Mandela Bay Metropole
- Authors: Bowler, Jennifer
- Date: 2019
- Subjects: Industrial relations, South Africa , Psychology, Industrial Work environment Industrial relations Labor unions
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/37150 , vital:34126
- Description: South Africa is consistently portrayed as having uncooperative union-management relationships which negatively impact competitiveness. However, the post-1994 labour legislation was specifically crafted with the intention of positioning the adversarial wealth distribution phase of the union-management relationship within centralised bargaining forums and promoting cooperative relationships within workplaces. The purpose of this study was to investigate whether within the South Africa context of global competitiveness, the employment relations institutions of centralised and decentralised collective bargaining, employee participation and involvement, in the context of organisational justice, have contributed to management, shop stewards and production employees developing effective1 collective and individual employment relationships positively associated with competitive individual and company performance. The targeted population were companies within the Nelson Mandela Metropolitan Area that were registered with one of the four bargaining councils, Automotive (NBF), Automotive component (MIBCO), New Tyre (NTMIBC) and Metal and Engineering (MEIBC). In addition, since the National Union of Metal Workers was the dominant union in all four of these councils, an additional criterion for potential participation was at least one NUMSA shop steward. Fourteen companies agreed to participate. In total 63 shop stewards, 82 managers and 660 production employees were surveyed using self-administered questionnaires. The results of the study identified that the three major stakeholders hold significantly different perceptions regarding the quality of the management-shop steward relationship, with management the most positive and production employees the least. Further, investigating the factors that influence the perceptions that management and shop stewards have of their relationship, it was identified that for management the most influential factor was their beliefs regarding the interdependent nature of the relationship. For the shop stewards the situation was more nuanced with beliefs regarding interdependence, the perceptions of shop steward-management climate within the bargaining council, satisfaction 1 Definition of an effective employment relationship: An effective employment relationship is one in which the parties successfully resolve issues arising from their conflicting interests and successfully pursue joint gains where they share common interests (Kochan & Katz, 1988) with bargaining council agreements and workplace human resource practices and procedural fairness all contributing factors to the quality of the shop steward-management relationship. The model tested for production employees investigated the relationship between the factors human resource practices, procedural fairness, the standardisation of work, the employees’ perception of the shop steward-management relationship and the relationship of the employees with both their supervisor and the organisation. The primary finding was that the perception that the production employees held regarding the shop steward-management relationship fully mediated the employees’ relationship with the organisation and partially mediated that with the supervisor. These findings confirm the mediating position occupied by shop stewards within unionised companies and without derogating the importance of supervisory-employee relationships, indicated the central importance of the management-shop steward relations in forging strong employee-manager and employee-organisational bonds. While the original purpose of the study included investigating the link between the key employment relationships, namely, shop steward-management, employee-supervisor and employee-organisation relationships, and company competitiveness, unfortunately due to the limited number of companies that participated, it was not possible to test a company level model that included company performance. However, tentative support was found for relationships between the shop steward-management relationship and company performance. This remains an area for further study.
- Full Text:
- Date Issued: 2019
- Authors: Bowler, Jennifer
- Date: 2019
- Subjects: Industrial relations, South Africa , Psychology, Industrial Work environment Industrial relations Labor unions
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/37150 , vital:34126
- Description: South Africa is consistently portrayed as having uncooperative union-management relationships which negatively impact competitiveness. However, the post-1994 labour legislation was specifically crafted with the intention of positioning the adversarial wealth distribution phase of the union-management relationship within centralised bargaining forums and promoting cooperative relationships within workplaces. The purpose of this study was to investigate whether within the South Africa context of global competitiveness, the employment relations institutions of centralised and decentralised collective bargaining, employee participation and involvement, in the context of organisational justice, have contributed to management, shop stewards and production employees developing effective1 collective and individual employment relationships positively associated with competitive individual and company performance. The targeted population were companies within the Nelson Mandela Metropolitan Area that were registered with one of the four bargaining councils, Automotive (NBF), Automotive component (MIBCO), New Tyre (NTMIBC) and Metal and Engineering (MEIBC). In addition, since the National Union of Metal Workers was the dominant union in all four of these councils, an additional criterion for potential participation was at least one NUMSA shop steward. Fourteen companies agreed to participate. In total 63 shop stewards, 82 managers and 660 production employees were surveyed using self-administered questionnaires. The results of the study identified that the three major stakeholders hold significantly different perceptions regarding the quality of the management-shop steward relationship, with management the most positive and production employees the least. Further, investigating the factors that influence the perceptions that management and shop stewards have of their relationship, it was identified that for management the most influential factor was their beliefs regarding the interdependent nature of the relationship. For the shop stewards the situation was more nuanced with beliefs regarding interdependence, the perceptions of shop steward-management climate within the bargaining council, satisfaction 1 Definition of an effective employment relationship: An effective employment relationship is one in which the parties successfully resolve issues arising from their conflicting interests and successfully pursue joint gains where they share common interests (Kochan & Katz, 1988) with bargaining council agreements and workplace human resource practices and procedural fairness all contributing factors to the quality of the shop steward-management relationship. The model tested for production employees investigated the relationship between the factors human resource practices, procedural fairness, the standardisation of work, the employees’ perception of the shop steward-management relationship and the relationship of the employees with both their supervisor and the organisation. The primary finding was that the perception that the production employees held regarding the shop steward-management relationship fully mediated the employees’ relationship with the organisation and partially mediated that with the supervisor. These findings confirm the mediating position occupied by shop stewards within unionised companies and without derogating the importance of supervisory-employee relationships, indicated the central importance of the management-shop steward relations in forging strong employee-manager and employee-organisational bonds. While the original purpose of the study included investigating the link between the key employment relationships, namely, shop steward-management, employee-supervisor and employee-organisation relationships, and company competitiveness, unfortunately due to the limited number of companies that participated, it was not possible to test a company level model that included company performance. However, tentative support was found for relationships between the shop steward-management relationship and company performance. This remains an area for further study.
- Full Text:
- Date Issued: 2019
Anthropological study on perceptions of gender inequality in soccer: the case of selected Tsakane township schools
- Bogopa, David Legodi, Kwatsha, Linda
- Authors: Bogopa, David Legodi , Kwatsha, Linda
- Date: 2019
- Subjects: Gender mainstreaming -- South Africa -- Gauteng , Sex discrimination Sex discrimination against women
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/45172 , vital:38260
- Description: This study sought to investigate the perception of gender inequality within sport policies in Gauteng province at the two schools, namely, Khombindlela Primary School and Reshogofaditswe Secondary School. The aim of this research was to determine the meaning of gender inequality from an anthropological perspective within the context of soccer in Gauteng Province at the two schools, namely, Khombindlela Primary School and Reshogofaditswe Secondary School and also to understand the issue of gender inequality in soccer in the post-apartheid period. The research objectives were as follows, firstly, to determine the impact of gender inequality in soccer at the two schools, namely, Khombindlela Primary School and Reshogofaditswe Secondary School. Secondly, the research sought to provide the recommendations for policy improvement within soccer in Gauteng Province and possibly at the nation level. Thirdly, the research also sought to add to the existing anthropological knowledge base on the impact of gender inequality on policy development relating to soccer. This research has followed the qualitative approach which includes, person to person interviews using an interview schedule. The researcher has also used observation as a research tool during the interviews. The data collection techniques employed in this study included interviews and observation (primary sources) and information gathered from relevant scholarly journals, books, newspapers, magazines, internet articles and sport policy documents (secondary sources). Ethics considerations were also covered from the proposal stage up to the final stage. The Marxist Feminist theoretical framework was used to understand issues of gender inequality in soccer particularly within the context of two Tsakane township schools, namely, Khombindlela Primary School and Reshogofaditswe Secondary School. Finally, a summary of each chapter was highlighted followed by the research findings and recommendations.
- Full Text:
- Date Issued: 2019
- Authors: Bogopa, David Legodi , Kwatsha, Linda
- Date: 2019
- Subjects: Gender mainstreaming -- South Africa -- Gauteng , Sex discrimination Sex discrimination against women
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/45172 , vital:38260
- Description: This study sought to investigate the perception of gender inequality within sport policies in Gauteng province at the two schools, namely, Khombindlela Primary School and Reshogofaditswe Secondary School. The aim of this research was to determine the meaning of gender inequality from an anthropological perspective within the context of soccer in Gauteng Province at the two schools, namely, Khombindlela Primary School and Reshogofaditswe Secondary School and also to understand the issue of gender inequality in soccer in the post-apartheid period. The research objectives were as follows, firstly, to determine the impact of gender inequality in soccer at the two schools, namely, Khombindlela Primary School and Reshogofaditswe Secondary School. Secondly, the research sought to provide the recommendations for policy improvement within soccer in Gauteng Province and possibly at the nation level. Thirdly, the research also sought to add to the existing anthropological knowledge base on the impact of gender inequality on policy development relating to soccer. This research has followed the qualitative approach which includes, person to person interviews using an interview schedule. The researcher has also used observation as a research tool during the interviews. The data collection techniques employed in this study included interviews and observation (primary sources) and information gathered from relevant scholarly journals, books, newspapers, magazines, internet articles and sport policy documents (secondary sources). Ethics considerations were also covered from the proposal stage up to the final stage. The Marxist Feminist theoretical framework was used to understand issues of gender inequality in soccer particularly within the context of two Tsakane township schools, namely, Khombindlela Primary School and Reshogofaditswe Secondary School. Finally, a summary of each chapter was highlighted followed by the research findings and recommendations.
- Full Text:
- Date Issued: 2019
Anti-HIV-1 integrase potency of methylgallate from Alchornea cordifolia using in vitro and in silico approaches:
- Noundou, Xavier S, Musyoka, Thommas M, Moses, Vuyani, Ndinteh, Derek T, Mnkandhla, Dumisani, Hoppe, Heinrich C, Tastan Bishop, Özlem, Krause, Rui W M
- Authors: Noundou, Xavier S , Musyoka, Thommas M , Moses, Vuyani , Ndinteh, Derek T , Mnkandhla, Dumisani , Hoppe, Heinrich C , Tastan Bishop, Özlem , Krause, Rui W M
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/162975 , vital:41001 , https://0-doi.org.wam.seals.ac.za/10.1038/s41598-019-41403-x
- Description: According to the 2018 report of the United Nations Programme on HIV/AIDS (UNAIDS), acquired immune deficiency syndrome (AIDS), a disease caused by the human immunodeficiency virus (HIV), remains a significant public health problem. The non-existence of a cure or effective vaccine for the disease and the associated emergence of resistant viral strains imply an urgent need for the discovery of novel anti-HIV drug candidates. The current study aimed to identify potential anti-retroviral compounds from Alchornea cordifolia.
- Full Text:
- Date Issued: 2019
- Authors: Noundou, Xavier S , Musyoka, Thommas M , Moses, Vuyani , Ndinteh, Derek T , Mnkandhla, Dumisani , Hoppe, Heinrich C , Tastan Bishop, Özlem , Krause, Rui W M
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/162975 , vital:41001 , https://0-doi.org.wam.seals.ac.za/10.1038/s41598-019-41403-x
- Description: According to the 2018 report of the United Nations Programme on HIV/AIDS (UNAIDS), acquired immune deficiency syndrome (AIDS), a disease caused by the human immunodeficiency virus (HIV), remains a significant public health problem. The non-existence of a cure or effective vaccine for the disease and the associated emergence of resistant viral strains imply an urgent need for the discovery of novel anti-HIV drug candidates. The current study aimed to identify potential anti-retroviral compounds from Alchornea cordifolia.
- Full Text:
- Date Issued: 2019
Anticancer evaluation of ruthenium (III) complexes with N-donor ligands tethered to coumarin or uracil moieties:
- Gramni, Larusha, Vukea, Nyeleti, Chakraborty, Abir, Samson, William J, Dingle, Laura M K, Xulu, Bheki, de la Mare, Jo-Anne, Edkins, Adrienne L, Booysen, Irvin N
- Authors: Gramni, Larusha , Vukea, Nyeleti , Chakraborty, Abir , Samson, William J , Dingle, Laura M K , Xulu, Bheki , de la Mare, Jo-Anne , Edkins, Adrienne L , Booysen, Irvin N
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163477 , vital:41041 , DOI: 10.1016/j.ica.2019.04.01
- Description: In this study, the synthesis and characterization of new paramagnetic ruthenium(III) complexes: cis-[RuCl2(urdpa)] (1) {Hurdpa = 6-((bis(pyridin-2-ylmethyl)amino)methyl)uracil} and fac-[RuCl3(chrdpa)] (2) {chrdpa = 4-((bis(pyridin-2-ylmethyl)amino)methyl)-7-methoxycoumarin} are reported. These metal complexes have been comprehensively characterized by an array of physicochemical techniques and the X-ray solid-state structures of 1 and Hurdpa have been attained.
- Full Text:
- Date Issued: 2019
- Authors: Gramni, Larusha , Vukea, Nyeleti , Chakraborty, Abir , Samson, William J , Dingle, Laura M K , Xulu, Bheki , de la Mare, Jo-Anne , Edkins, Adrienne L , Booysen, Irvin N
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163477 , vital:41041 , DOI: 10.1016/j.ica.2019.04.01
- Description: In this study, the synthesis and characterization of new paramagnetic ruthenium(III) complexes: cis-[RuCl2(urdpa)] (1) {Hurdpa = 6-((bis(pyridin-2-ylmethyl)amino)methyl)uracil} and fac-[RuCl3(chrdpa)] (2) {chrdpa = 4-((bis(pyridin-2-ylmethyl)amino)methyl)-7-methoxycoumarin} are reported. These metal complexes have been comprehensively characterized by an array of physicochemical techniques and the X-ray solid-state structures of 1 and Hurdpa have been attained.
- Full Text:
- Date Issued: 2019
Anticholinesterase and Antioxidant Activities of Spilanthes filicaulis Whole Plant Extracts for the Management of Alzheimer’s Disease
- Elufioye, Taiwo O., Unachukwu, Cynthia C., Oyedeji, Adebola O.
- Authors: Elufioye, Taiwo O. , Unachukwu, Cynthia C. , Oyedeji, Adebola O.
- Date: 2019
- Subjects: Alzheimer’s disease , Cholinesterase inhibitors , Antioxidants , Spilanthes , Flavonoids , Phenolic
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/6534 , vital:46450 , xlink:href="https://10.2174/1573408015666190730113405"
- Description: Background: Spilanthes filicaulis is a tropical herb implicated as a memory enhancer in ethnomedicine. Objective: The study investigated acetyl/butyryl cholinesterase inhibitory and antioxidant activities of different extracts of S. filicaulis whole plant and correlated them to its phytochemical constituents. Methods: The powdered whole plant was successively extracted with n-hexane, ethyl acetate and methanol. Acetyl cholinesterase (AChE) and Butyryl cholinesterase (BuChE) inhibitory activity were evaluated by Ellman colorimetry assay. Antioxidant activity was tested using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing power and nitric oxide scavenging assays. Total phenolic, flavonoid and tannin were estimated using standard methods. Correlation was determined using Quest Graph™ Regression Calculator. Results: Various extracts exhibited concentration-dependent AChE and BuChE inhibitory activity with ethyl acetate extract being the highest with IC50 of 0.77 μg/mL and 0.92 μg/mL for AChE and BuChE respectively. The ethyl acetate extract also showed the highest reducing power when compared with the other extracts. The methanol extract had slightly higher phenolic and flavonoid content and showed the highest DPPH radical scavenging effect. DPPH scavenging, AChE and BuChE inhibition had high correlation with the total flavonoid content with R2 values of 1.00, 0.800 and 0.992 respectively while nitric oxide scavenging had high correlation with phenolics and tannins with R2 = 0.942 and 0.806 respectively. Conclusion: These results show that the extracts of the whole plant of S. filicaulis possess significant AChE/BuChE inhibitory and antioxidant properties, mostly due to its flavonoid content, suggesting the possible use of the plant in neurodegenerative diseases such as AD.
- Full Text:
- Date Issued: 2019
- Authors: Elufioye, Taiwo O. , Unachukwu, Cynthia C. , Oyedeji, Adebola O.
- Date: 2019
- Subjects: Alzheimer’s disease , Cholinesterase inhibitors , Antioxidants , Spilanthes , Flavonoids , Phenolic
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/6534 , vital:46450 , xlink:href="https://10.2174/1573408015666190730113405"
- Description: Background: Spilanthes filicaulis is a tropical herb implicated as a memory enhancer in ethnomedicine. Objective: The study investigated acetyl/butyryl cholinesterase inhibitory and antioxidant activities of different extracts of S. filicaulis whole plant and correlated them to its phytochemical constituents. Methods: The powdered whole plant was successively extracted with n-hexane, ethyl acetate and methanol. Acetyl cholinesterase (AChE) and Butyryl cholinesterase (BuChE) inhibitory activity were evaluated by Ellman colorimetry assay. Antioxidant activity was tested using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing power and nitric oxide scavenging assays. Total phenolic, flavonoid and tannin were estimated using standard methods. Correlation was determined using Quest Graph™ Regression Calculator. Results: Various extracts exhibited concentration-dependent AChE and BuChE inhibitory activity with ethyl acetate extract being the highest with IC50 of 0.77 μg/mL and 0.92 μg/mL for AChE and BuChE respectively. The ethyl acetate extract also showed the highest reducing power when compared with the other extracts. The methanol extract had slightly higher phenolic and flavonoid content and showed the highest DPPH radical scavenging effect. DPPH scavenging, AChE and BuChE inhibition had high correlation with the total flavonoid content with R2 values of 1.00, 0.800 and 0.992 respectively while nitric oxide scavenging had high correlation with phenolics and tannins with R2 = 0.942 and 0.806 respectively. Conclusion: These results show that the extracts of the whole plant of S. filicaulis possess significant AChE/BuChE inhibitory and antioxidant properties, mostly due to its flavonoid content, suggesting the possible use of the plant in neurodegenerative diseases such as AD.
- Full Text:
- Date Issued: 2019
Antihypertensive effects of the hydroethanol extract of Senecio serratuloides DC in rats
- Tata, Charlotte Mungho, Sewani-Rusike, Constance Rufaro, Oyedeji, Opeoluwa Oyehan, Gwebu, Ephraim Tobela, Mahlakata, Fikile, Nkeh-Chungag, Benedicta Ngwenchi
- Authors: Tata, Charlotte Mungho , Sewani-Rusike, Constance Rufaro , Oyedeji, Opeoluwa Oyehan , Gwebu, Ephraim Tobela , Mahlakata, Fikile , Nkeh-Chungag, Benedicta Ngwenchi
- Date: 2019
- Subjects: South Africa Hypertension Computer File
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/5847 , vital:44656 , https://doi.org/10.1186/s12906-019-2463-2
- Description: Senecio serratuloides DC is used in folk medicine for treating hypertension, skin disorders, internal and external sores, rashes, burns and wounds. This study aimed at investigating the antihypertensive effects of the hydroethanol extract of S. serratuloides (HESS) in N-Nitro-L-arginine methyl ester (L-NAME) induced hypertension in rats. Methods: Acute toxicity of HESS was first determined to provide guidance on doses to be used in this study. Lorke’s method was used to determine safety of the extract in mice. Female Wistar rats were treated orally once daily with L-NAME (40 mg/kg) for 4 weeks and then concomitantly with L-NAME (20 mg/kg) and plant extract (150 and 300 mg/kg), captopril (20 mg/kg) or saline as per assigned group for 2 weeks followed by a 2-week period of assigned treatments only. Blood pressure was monitored weekly. Lipid profile, nitric oxide, renin and angiotensin II concentrations were determined in serum while mineralocorticoid receptor concentration was quantified in the kidney homogenate. Nitric oxide (NO) concentration was determined in serum and cardiac histology performed. Results HESS was found to be non-toxic, having a LD50 greater than 5000 mg/kg. Blood pressure increased progressively in all animals from the second week of L-NAME treatment. HESS treatment significantly and dose-dependently lowered systolic blood pressure (p less 0.001), diastolic blood pressure (p less 0.01), low density lipoprotein cholesterol (p less 0.01) and triglycerides (p less 0.01). It significantly prevented L-NAME induced decrease in serum angiotensin II (p less 0.01), high density lipoprotein cholesterol (p less 0.001) and serum nitric oxide concentrations (p less 0.001). HESS also significantly (p less 0.01) prevented collagen deposition in cardiac tissue. Conclusion The hydro-ethanol extract of Senecio serratuloides showed antihypertensive, antihyperlipidemic and cardioprotective effects in rats thus confirming its usefulness in traditional antihypertensive therapy and potential for antihypertensive drug development.
- Full Text:
- Date Issued: 2019
- Authors: Tata, Charlotte Mungho , Sewani-Rusike, Constance Rufaro , Oyedeji, Opeoluwa Oyehan , Gwebu, Ephraim Tobela , Mahlakata, Fikile , Nkeh-Chungag, Benedicta Ngwenchi
- Date: 2019
- Subjects: South Africa Hypertension Computer File
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/5847 , vital:44656 , https://doi.org/10.1186/s12906-019-2463-2
- Description: Senecio serratuloides DC is used in folk medicine for treating hypertension, skin disorders, internal and external sores, rashes, burns and wounds. This study aimed at investigating the antihypertensive effects of the hydroethanol extract of S. serratuloides (HESS) in N-Nitro-L-arginine methyl ester (L-NAME) induced hypertension in rats. Methods: Acute toxicity of HESS was first determined to provide guidance on doses to be used in this study. Lorke’s method was used to determine safety of the extract in mice. Female Wistar rats were treated orally once daily with L-NAME (40 mg/kg) for 4 weeks and then concomitantly with L-NAME (20 mg/kg) and plant extract (150 and 300 mg/kg), captopril (20 mg/kg) or saline as per assigned group for 2 weeks followed by a 2-week period of assigned treatments only. Blood pressure was monitored weekly. Lipid profile, nitric oxide, renin and angiotensin II concentrations were determined in serum while mineralocorticoid receptor concentration was quantified in the kidney homogenate. Nitric oxide (NO) concentration was determined in serum and cardiac histology performed. Results HESS was found to be non-toxic, having a LD50 greater than 5000 mg/kg. Blood pressure increased progressively in all animals from the second week of L-NAME treatment. HESS treatment significantly and dose-dependently lowered systolic blood pressure (p less 0.001), diastolic blood pressure (p less 0.01), low density lipoprotein cholesterol (p less 0.01) and triglycerides (p less 0.01). It significantly prevented L-NAME induced decrease in serum angiotensin II (p less 0.01), high density lipoprotein cholesterol (p less 0.001) and serum nitric oxide concentrations (p less 0.001). HESS also significantly (p less 0.01) prevented collagen deposition in cardiac tissue. Conclusion The hydro-ethanol extract of Senecio serratuloides showed antihypertensive, antihyperlipidemic and cardioprotective effects in rats thus confirming its usefulness in traditional antihypertensive therapy and potential for antihypertensive drug development.
- Full Text:
- Date Issued: 2019
Antihypertensive effects of the hydroethanol extract of Senecio serratuloides DC in rats
- Tata, Charlotte Mungho, Sewani-Rusike, Constance Rufaro, Oyedeji, Opeoluwa Oyehan, Gwebu, Ephraim Tobela, Mahlakata, Fikile, Nkeh-Chungag, Benedicta Ngwenchi
- Authors: Tata, Charlotte Mungho , Sewani-Rusike, Constance Rufaro , Oyedeji, Opeoluwa Oyehan , Gwebu, Ephraim Tobela , Mahlakata, Fikile , Nkeh-Chungag, Benedicta Ngwenchi
- Date: 2019
- Subjects: South Africa Hypertension Computer File
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/5842 , vital:44654 , https://doi.org/10.1186/s12906-019-2463-2
- Description: Senecio serratuloides DC is used in folk medicine for treating hypertension, skin disorders, internal and external sores, rashes, burns and wounds. This study aimed at investigating the antihypertensive effects of the hydroethanol extract of S. serratuloides (HESS) in N-Nitro-L-arginine methyl ester (L-NAME) induced hypertension in rats. Methods: Acute toxicity of HESS was first determined to provide guidance on doses to be used in this study. Lorke’s method was used to determine safety of the extract in mice. Female Wistar rats were treated orally once daily with L-NAME (40 mg/kg) for 4 weeks and then concomitantly with L-NAME (20 mg/kg) and plant extract (150 and 300 mg/kg), captopril (20 mg/kg) or saline as per assigned group for 2 weeks followed by a 2-week period of assigned treatments only. Blood pressure was monitored weekly. Lipid profile, nitric oxide, renin and angiotensin II concentrations were determined in serum while mineralocorticoid receptor concentration was quantified in the kidney homogenate. Nitric oxide (NO) concentration was determined in serum and cardiac histology performed. Results HESS was found to be non-toxic, having a LD50 greater than 5000 mg/kg. Blood pressure increased progressively in all animals from the second week of L-NAME treatment. HESS treatment significantly and dose-dependently lowered systolic blood pressure (p less 0.001), diastolic blood pressure (p less 0.01), low density lipoprotein cholesterol (p less 0.01) and triglycerides (p less 0.01). It significantly prevented L-NAME induced decrease in serum angiotensin II (p less 0.01), high density lipoprotein cholesterol (p less 0.001) and serum nitric oxide concentrations (p less 0.001). HESS also significantly (p less 0.01) prevented collagen deposition in cardiac tissue. Conclusion The hydro-ethanol extract of Senecio serratuloides showed antihypertensive, antihyperlipidemic and cardioprotective effects in rats thus confirming its usefulness in traditional antihypertensive therapy and potential for antihypertensive drug development.
- Full Text:
- Date Issued: 2019
- Authors: Tata, Charlotte Mungho , Sewani-Rusike, Constance Rufaro , Oyedeji, Opeoluwa Oyehan , Gwebu, Ephraim Tobela , Mahlakata, Fikile , Nkeh-Chungag, Benedicta Ngwenchi
- Date: 2019
- Subjects: South Africa Hypertension Computer File
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/5842 , vital:44654 , https://doi.org/10.1186/s12906-019-2463-2
- Description: Senecio serratuloides DC is used in folk medicine for treating hypertension, skin disorders, internal and external sores, rashes, burns and wounds. This study aimed at investigating the antihypertensive effects of the hydroethanol extract of S. serratuloides (HESS) in N-Nitro-L-arginine methyl ester (L-NAME) induced hypertension in rats. Methods: Acute toxicity of HESS was first determined to provide guidance on doses to be used in this study. Lorke’s method was used to determine safety of the extract in mice. Female Wistar rats were treated orally once daily with L-NAME (40 mg/kg) for 4 weeks and then concomitantly with L-NAME (20 mg/kg) and plant extract (150 and 300 mg/kg), captopril (20 mg/kg) or saline as per assigned group for 2 weeks followed by a 2-week period of assigned treatments only. Blood pressure was monitored weekly. Lipid profile, nitric oxide, renin and angiotensin II concentrations were determined in serum while mineralocorticoid receptor concentration was quantified in the kidney homogenate. Nitric oxide (NO) concentration was determined in serum and cardiac histology performed. Results HESS was found to be non-toxic, having a LD50 greater than 5000 mg/kg. Blood pressure increased progressively in all animals from the second week of L-NAME treatment. HESS treatment significantly and dose-dependently lowered systolic blood pressure (p less 0.001), diastolic blood pressure (p less 0.01), low density lipoprotein cholesterol (p less 0.01) and triglycerides (p less 0.01). It significantly prevented L-NAME induced decrease in serum angiotensin II (p less 0.01), high density lipoprotein cholesterol (p less 0.001) and serum nitric oxide concentrations (p less 0.001). HESS also significantly (p less 0.01) prevented collagen deposition in cardiac tissue. Conclusion The hydro-ethanol extract of Senecio serratuloides showed antihypertensive, antihyperlipidemic and cardioprotective effects in rats thus confirming its usefulness in traditional antihypertensive therapy and potential for antihypertensive drug development.
- Full Text:
- Date Issued: 2019
Antimicrobial resistance awareness program at Settlers Hospital
- Manhanzva, Rufaro Immaculate
- Authors: Manhanzva, Rufaro Immaculate
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/97712 , vital:31475
- Description: Expected release date-April 2021
- Full Text: false
- Date Issued: 2019
- Authors: Manhanzva, Rufaro Immaculate
- Date: 2019
- Language: English
- Type: text , Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/97712 , vital:31475
- Description: Expected release date-April 2021
- Full Text: false
- Date Issued: 2019
Antiplasmodial Activity of the n-Hexane Extract from Pleurotus ostreatus (Jacq. ex. Fr) P. Kumm
- Afieroho, Ozadheoghene E, Siwe-Noundou, Xavier, Onyia, Chiazor P, Festus, Osamuyi H, Chukwu, Elizabeth C, Adedokun, Olutayo M, Isaacs, Michelle, Hoppe, Heinrich, Krause, Rui W M, Abo, Kio A
- Authors: Afieroho, Ozadheoghene E , Siwe-Noundou, Xavier , Onyia, Chiazor P , Festus, Osamuyi H , Chukwu, Elizabeth C , Adedokun, Olutayo M , Isaacs, Michelle , Hoppe, Heinrich , Krause, Rui W M , Abo, Kio A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/194981 , vital:45516 , xlink:href="https://doi.org/10.4274/tjps.18894"
- Description: Objectives: Several mushrooms species have been reported to be nematophagous and antiprotozoan. This study reported the antiplasmodial and cytotoxic properties of the n-hexane extract from the edible mushroom Pleurotus ostreatus and the isolation of a sterol from the extract. Materials and Methods: Antiplasmodial and cytotoxicity assays were done in vitro using the plasmodium lactate dehydrogenase assay and human HeLa cervical cell lines, respectively. The structure of the isolated compound from the n-hexane extract was elucidated using spectroscopic techniques. Results: The n-hexane extract (yield: 0.93% w/w) showed dose dependent antiplasmodial activity with the trend in parasite inhibition of: chloroquine (IC50=0.016 μg/mL) > n-hexane extract (IC50=25.18 μg/mL). It also showed mild cytotoxicity (IC50>100 μg/mL; selectivity index >4) compared to the reference drug emetine (IC50=0.013 μg/mL). The known sterol, ergostan-5,7,22-trien-3-ol, was isolated and characterized from the extract. Conclusion: This study reporting for the first time the antiplasmodial activity of P. ostreatus revealed its nutraceutical potential in the management of malaria.
- Full Text:
- Date Issued: 2019
- Authors: Afieroho, Ozadheoghene E , Siwe-Noundou, Xavier , Onyia, Chiazor P , Festus, Osamuyi H , Chukwu, Elizabeth C , Adedokun, Olutayo M , Isaacs, Michelle , Hoppe, Heinrich , Krause, Rui W M , Abo, Kio A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/194981 , vital:45516 , xlink:href="https://doi.org/10.4274/tjps.18894"
- Description: Objectives: Several mushrooms species have been reported to be nematophagous and antiprotozoan. This study reported the antiplasmodial and cytotoxic properties of the n-hexane extract from the edible mushroom Pleurotus ostreatus and the isolation of a sterol from the extract. Materials and Methods: Antiplasmodial and cytotoxicity assays were done in vitro using the plasmodium lactate dehydrogenase assay and human HeLa cervical cell lines, respectively. The structure of the isolated compound from the n-hexane extract was elucidated using spectroscopic techniques. Results: The n-hexane extract (yield: 0.93% w/w) showed dose dependent antiplasmodial activity with the trend in parasite inhibition of: chloroquine (IC50=0.016 μg/mL) > n-hexane extract (IC50=25.18 μg/mL). It also showed mild cytotoxicity (IC50>100 μg/mL; selectivity index >4) compared to the reference drug emetine (IC50=0.013 μg/mL). The known sterol, ergostan-5,7,22-trien-3-ol, was isolated and characterized from the extract. Conclusion: This study reporting for the first time the antiplasmodial activity of P. ostreatus revealed its nutraceutical potential in the management of malaria.
- Full Text:
- Date Issued: 2019
Application of computational methods in elucidating the isomerization step in the biosynthesis of coumarins
- Authors: Tshiwawa, Tendamudzimu
- Date: 2019
- Subjects: Coumarins , Isomerization , Biosynthesis , Organic compounds -- Synthesis , Cinnamic acid
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/67646 , vital:29124
- Description: The identity of the enzyme(s) responsible for the biosynthetic transformation of cinnamic acid derivatives to important, naturally occurring coumarins has yet to be established. This study constitutes a high-level theoretical analysis of the possibility that a recently reported molecular mechanism of the synthesis of coumarins from Baylis-Hillman adducts, may provide a viable model for three critical phases in the biosynthetic pathway Particular attention has been given to the first of these phases: i) E→Z isomerisation of the cinnamic acid precursor; ii) Cyclisation (lactonisation) to the hemi-acetal intermediate; and ii) Dehydration to afford the coumarin derivative. In order to accomplish this analysis, an enzyme capable, theoretically, of effecting this E→Z isomerisation required identification, and its potential involvement in the transformation mechanism explored. Combined Molecular Mechanics and high-level Quantum Mechanical/DFT calculations were used to access complementary models of appropriate complexes and relevant processes within the enzyme active sites of a range of eleven Chalcone Isomerase (CHI) enzyme candidates, the structures of which were downloaded from the Protein Data Bank. Detailed B3LYP/6-31+G(d,p) calculations have provided pictures of the relative populations of conformations within the ensemble of conformations available at normal temperatures. Conformations of several protonation states of cinnamic acid derivatives have been studied in this way, and the results obtained showed that coupled protonation and deprotonation of (E)-o-coumaric acid provides a viable approach to achieve the E→Z isomerization. In silico docking of the B3LYP/6-31+G(d,p) optimized (E)-o-coumaric acid derivatives in the active sites of each of the candidate CHI enzymes (CHI) revealed that (E)-o-coumaric acid fits well within the active sites of Medicago Sativa CHI crystallographic structures with 1FM8 showing best potential for not only accommodating (E)-o-coumaric acid , but also providing appropriate protein active site residues to effect the simultaneous protonation and deprotonation of the substrate , two residues being optimally placed to facilitate these critical processes. Further exploration of the chemical properties and qualities of selected CHI enzymes, undertaken using High Throughput Virtual Screening (HTVS), confirmed 1FM8 as a viable choice for further studies of the enzyme-catalysed E→Z isomerization of (E)-o-coumaric acid. A molecular dynamics study, performed to further evaluate the evolution of (E)-o-coumaric acid in the CHI active site over time, showed that the ligand in the 1FM8 active site is not only stable, but also that the desired protein-ligand interactions persist throughout the simulation period to facilitate the E→Z isomerization. An integrated molecular orbital and molecular mechanics (ONIOM) study of the 1FM8-(E)-o-coumaric acid complex, involving the direct protonation and deprotonation of the ligand by protein residues; has provided a plausible mechanism for the E → Z isomerization of (E)-o-coumaric acid within the 1FM8 active site; a transition state complex (with an activation energy of ca. 50 kCal.mol-1) has been located and its connection with both the (E)- and (Z)-o-coumaric acid isomer has been confirmed by Intrinsic Reaction Coordinate (IRC) calculations. More realistic models of the 1FM8-(E)-o-coumaric acid complex, with the inclusion of water solvent molecules, have been obtained at both the QM/MM and adaptive QM/MM levels which simulate the dynamic active site at the QM level. The results indicate that the simultaneous protonation and deprotonation of (E)-o-coumaric acid within the CHI enzyme is a water-mediated process – a conclusion consistent with similar reported processes. Visual inspection of the 1FM8-(Z)-o-coumaric acid complex reveals both the necessary orientation of the phenolic and carboxylic acid moieties of the (Z)-o-coumaric acid and the presence of appropriate, proximal active site residues with the potential to permit catalysis of the subsequent lactonisation and dehydration steps required to generate coumarin.
- Full Text:
- Date Issued: 2019
- Authors: Tshiwawa, Tendamudzimu
- Date: 2019
- Subjects: Coumarins , Isomerization , Biosynthesis , Organic compounds -- Synthesis , Cinnamic acid
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/67646 , vital:29124
- Description: The identity of the enzyme(s) responsible for the biosynthetic transformation of cinnamic acid derivatives to important, naturally occurring coumarins has yet to be established. This study constitutes a high-level theoretical analysis of the possibility that a recently reported molecular mechanism of the synthesis of coumarins from Baylis-Hillman adducts, may provide a viable model for three critical phases in the biosynthetic pathway Particular attention has been given to the first of these phases: i) E→Z isomerisation of the cinnamic acid precursor; ii) Cyclisation (lactonisation) to the hemi-acetal intermediate; and ii) Dehydration to afford the coumarin derivative. In order to accomplish this analysis, an enzyme capable, theoretically, of effecting this E→Z isomerisation required identification, and its potential involvement in the transformation mechanism explored. Combined Molecular Mechanics and high-level Quantum Mechanical/DFT calculations were used to access complementary models of appropriate complexes and relevant processes within the enzyme active sites of a range of eleven Chalcone Isomerase (CHI) enzyme candidates, the structures of which were downloaded from the Protein Data Bank. Detailed B3LYP/6-31+G(d,p) calculations have provided pictures of the relative populations of conformations within the ensemble of conformations available at normal temperatures. Conformations of several protonation states of cinnamic acid derivatives have been studied in this way, and the results obtained showed that coupled protonation and deprotonation of (E)-o-coumaric acid provides a viable approach to achieve the E→Z isomerization. In silico docking of the B3LYP/6-31+G(d,p) optimized (E)-o-coumaric acid derivatives in the active sites of each of the candidate CHI enzymes (CHI) revealed that (E)-o-coumaric acid fits well within the active sites of Medicago Sativa CHI crystallographic structures with 1FM8 showing best potential for not only accommodating (E)-o-coumaric acid , but also providing appropriate protein active site residues to effect the simultaneous protonation and deprotonation of the substrate , two residues being optimally placed to facilitate these critical processes. Further exploration of the chemical properties and qualities of selected CHI enzymes, undertaken using High Throughput Virtual Screening (HTVS), confirmed 1FM8 as a viable choice for further studies of the enzyme-catalysed E→Z isomerization of (E)-o-coumaric acid. A molecular dynamics study, performed to further evaluate the evolution of (E)-o-coumaric acid in the CHI active site over time, showed that the ligand in the 1FM8 active site is not only stable, but also that the desired protein-ligand interactions persist throughout the simulation period to facilitate the E→Z isomerization. An integrated molecular orbital and molecular mechanics (ONIOM) study of the 1FM8-(E)-o-coumaric acid complex, involving the direct protonation and deprotonation of the ligand by protein residues; has provided a plausible mechanism for the E → Z isomerization of (E)-o-coumaric acid within the 1FM8 active site; a transition state complex (with an activation energy of ca. 50 kCal.mol-1) has been located and its connection with both the (E)- and (Z)-o-coumaric acid isomer has been confirmed by Intrinsic Reaction Coordinate (IRC) calculations. More realistic models of the 1FM8-(E)-o-coumaric acid complex, with the inclusion of water solvent molecules, have been obtained at both the QM/MM and adaptive QM/MM levels which simulate the dynamic active site at the QM level. The results indicate that the simultaneous protonation and deprotonation of (E)-o-coumaric acid within the CHI enzyme is a water-mediated process – a conclusion consistent with similar reported processes. Visual inspection of the 1FM8-(Z)-o-coumaric acid complex reveals both the necessary orientation of the phenolic and carboxylic acid moieties of the (Z)-o-coumaric acid and the presence of appropriate, proximal active site residues with the potential to permit catalysis of the subsequent lactonisation and dehydration steps required to generate coumarin.
- Full Text:
- Date Issued: 2019
Application of some missing data techniques in estimating missing data in high blood pressure covariates
- Authors: Odeyemi, A. S
- Date: 2019
- Subjects: Missing observations (Statistics) Hypertension
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15189 , vital:40195
- Description: Cases recorded with high blood pressure are a major concern in both public and private hospitals. Adequate provision of health information of patients relating to high blood pressure in Eastern Cape Hospitals hinges so much on the outcome of statistical analysis results. The usual statistical methodologies become inadequate in handling statistical analysis of data collected due to incomplete patients’ information stored in the hospital database. From time to time, new methods are developed to address the problem of missing data. High blood pressure is linked to a lot of diseases such hypertension, cardiovascular disease, kidney disease and stroke. In this study, we developed a new method for addressing the problem of missing data in assessing model used for estimating missing values in terms of minimum errors(using RMSE, MAE, and SE) and goodness-of-fits(using 2 R and adjusted 2 R ) of this model and P-value. . The study compared six different methods: Original data (OD), Listwise deletion (LD), Mean imputations (MEI), Mean above (MA), and Mean above below(MAB) and two steps nearest neighbour (2-NN).The comparison was performed using original data set, and missing values at 5%, 10%, 20%, 30% were simulated on Framingham risk scores under MCAR and MAR simulation on BMI values given some assumptions. Five performance indicators were used to describe the model minimum errors and goodness of fit for all the methods. The results showed that the 2-NN is the best replacement method at lower levels (5% and10%) of missing values while MA and MEI performed best at higher levels(15% and 20%) of missing values. All comparison was based on estimates closest to those of the original data where no value was missing. MAR results showed that 2-NN performed better than LD,MA,MAB, and MEI at 5%,10%, and 20% levels of missing data in terms of absolute difference in p-value to original data.
- Full Text:
- Date Issued: 2019
- Authors: Odeyemi, A. S
- Date: 2019
- Subjects: Missing observations (Statistics) Hypertension
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15189 , vital:40195
- Description: Cases recorded with high blood pressure are a major concern in both public and private hospitals. Adequate provision of health information of patients relating to high blood pressure in Eastern Cape Hospitals hinges so much on the outcome of statistical analysis results. The usual statistical methodologies become inadequate in handling statistical analysis of data collected due to incomplete patients’ information stored in the hospital database. From time to time, new methods are developed to address the problem of missing data. High blood pressure is linked to a lot of diseases such hypertension, cardiovascular disease, kidney disease and stroke. In this study, we developed a new method for addressing the problem of missing data in assessing model used for estimating missing values in terms of minimum errors(using RMSE, MAE, and SE) and goodness-of-fits(using 2 R and adjusted 2 R ) of this model and P-value. . The study compared six different methods: Original data (OD), Listwise deletion (LD), Mean imputations (MEI), Mean above (MA), and Mean above below(MAB) and two steps nearest neighbour (2-NN).The comparison was performed using original data set, and missing values at 5%, 10%, 20%, 30% were simulated on Framingham risk scores under MCAR and MAR simulation on BMI values given some assumptions. Five performance indicators were used to describe the model minimum errors and goodness of fit for all the methods. The results showed that the 2-NN is the best replacement method at lower levels (5% and10%) of missing values while MA and MEI performed best at higher levels(15% and 20%) of missing values. All comparison was based on estimates closest to those of the original data where no value was missing. MAR results showed that 2-NN performed better than LD,MA,MAB, and MEI at 5%,10%, and 20% levels of missing data in terms of absolute difference in p-value to original data.
- Full Text:
- Date Issued: 2019