Securing softswitches from malicious attacks
- Authors: Opie, Jake Weyman
- Date: 2007
- Subjects: Internet telephony -- Security measures , Computer networks -- Security measures , Digital telephone systems , Communication -- Technological innovations , Computer network protocols , TCP/IP (Computer network protocol) , Switching theory
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4683 , http://hdl.handle.net/10962/d1007714 , Internet telephony -- Security measures , Computer networks -- Security measures , Digital telephone systems , Communication -- Technological innovations , Computer network protocols , TCP/IP (Computer network protocol) , Switching theory
- Description: Traditionally, real-time communication, such as voice calls, has run on separate, closed networks. Of all the limitations that these networks had, the ability of malicious attacks to cripple communication was not a crucial one. This situation has changed radically now that real-time communication and data have merged to share the same network. The objective of this project is to investigate the securing of softswitches with functionality similar to Private Branch Exchanges (PBX) from malicious attacks. The focus of the project will be a practical investigation of how to secure ILANGA, an ASTERISK-based system under development at Rhodes University. The practical investigation that focuses on ILANGA is based on performing six varied experiments on the different components of ILANGA. Before the six experiments are performed, basic preliminary security measures and the restrictions placed on the access to the database are discussed. The outcomes of these experiments are discussed and the precise reasons why these attacks were either successful or unsuccessful are given. Suggestions of a theoretical nature on how to defend against the successful attacks are also presented.
- Full Text:
- Date Issued: 2007
- Authors: Opie, Jake Weyman
- Date: 2007
- Subjects: Internet telephony -- Security measures , Computer networks -- Security measures , Digital telephone systems , Communication -- Technological innovations , Computer network protocols , TCP/IP (Computer network protocol) , Switching theory
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4683 , http://hdl.handle.net/10962/d1007714 , Internet telephony -- Security measures , Computer networks -- Security measures , Digital telephone systems , Communication -- Technological innovations , Computer network protocols , TCP/IP (Computer network protocol) , Switching theory
- Description: Traditionally, real-time communication, such as voice calls, has run on separate, closed networks. Of all the limitations that these networks had, the ability of malicious attacks to cripple communication was not a crucial one. This situation has changed radically now that real-time communication and data have merged to share the same network. The objective of this project is to investigate the securing of softswitches with functionality similar to Private Branch Exchanges (PBX) from malicious attacks. The focus of the project will be a practical investigation of how to secure ILANGA, an ASTERISK-based system under development at Rhodes University. The practical investigation that focuses on ILANGA is based on performing six varied experiments on the different components of ILANGA. Before the six experiments are performed, basic preliminary security measures and the restrictions placed on the access to the database are discussed. The outcomes of these experiments are discussed and the precise reasons why these attacks were either successful or unsuccessful are given. Suggestions of a theoretical nature on how to defend against the successful attacks are also presented.
- Full Text:
- Date Issued: 2007
Securitisation and its application to low cost housing finance in South Africa
- Authors: Zimbwa, Allan Golden
- Date: 2007
- Subjects: South Africa. Constitution , Human rights -- Government policy -- South Africa , Right to housing -- South Africa , Housing -- Law and legislation -- South Africa , Housing policy -- South Africa , Low income housing -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1011 , http://hdl.handle.net/10962/d1002746 , South Africa. Constitution , Human rights -- Government policy -- South Africa , Right to housing -- South Africa , Housing -- Law and legislation -- South Africa , Housing policy -- South Africa , Low income housing -- South Africa
- Description: Section 26 of the Constitution of South Africa Act 108 of 1996 provides that housing is a basic human right and that the government must take reasonable legislative and other measures to achieve the realisation of this right. A number of measures were taken to try to resolve this socio-economic issue. A number of housing institutions were established , various pieces of legislation were passed and housing subsidies were provided. However, housing backlogs remain a challenge. In March 1994 the housing backlog was estimated between 1,3 and 1,8 million units. When more than a million houses were provided by 2001 , the housing backlog had increased to between 2 and 3 million houses. To date subsidies in excess of R29 billion have been spent on housing provision. A study by the Department of Housing concluded that, at the current rate of increase of housing funding vis-a-vis the growing backlog and rapid urbanisation, the household backlog will not be changed in ten years' time. The United States of America (USA) had a similar low cost housing problem, but securitisation alleviated it with the participation of government agencies Fannie Mae, Ginnie Mae and Freddie Mac. In South Africa, the NHFC tried to emulate the USA model by establishing Gateway Home Loans (Pty) Limited (Gateway) in 1999. Gateway, however, was not a success. This research investigates whether securitisation can be applied in South Africa to alleviate the low cost housing issue. The study finds that there is a credit availability gap for the low income sector earning less than R8 000 per month because of the perceived risk of default and unwillingness by banks to lend to this sector. The increase in housing backlog that continues unabated, inadequate housing finance system to low income earners, the lessons learnt from the failure of Gateway, the success factors of the USA securitisation model and the sound and sophisticated South African financial system are the rationale for applying securitisation. A proposal of how to effectively apply securitisation to low cost housing in South Africa is provided with recommendations to revive the primary market.
- Full Text:
- Date Issued: 2007
- Authors: Zimbwa, Allan Golden
- Date: 2007
- Subjects: South Africa. Constitution , Human rights -- Government policy -- South Africa , Right to housing -- South Africa , Housing -- Law and legislation -- South Africa , Housing policy -- South Africa , Low income housing -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1011 , http://hdl.handle.net/10962/d1002746 , South Africa. Constitution , Human rights -- Government policy -- South Africa , Right to housing -- South Africa , Housing -- Law and legislation -- South Africa , Housing policy -- South Africa , Low income housing -- South Africa
- Description: Section 26 of the Constitution of South Africa Act 108 of 1996 provides that housing is a basic human right and that the government must take reasonable legislative and other measures to achieve the realisation of this right. A number of measures were taken to try to resolve this socio-economic issue. A number of housing institutions were established , various pieces of legislation were passed and housing subsidies were provided. However, housing backlogs remain a challenge. In March 1994 the housing backlog was estimated between 1,3 and 1,8 million units. When more than a million houses were provided by 2001 , the housing backlog had increased to between 2 and 3 million houses. To date subsidies in excess of R29 billion have been spent on housing provision. A study by the Department of Housing concluded that, at the current rate of increase of housing funding vis-a-vis the growing backlog and rapid urbanisation, the household backlog will not be changed in ten years' time. The United States of America (USA) had a similar low cost housing problem, but securitisation alleviated it with the participation of government agencies Fannie Mae, Ginnie Mae and Freddie Mac. In South Africa, the NHFC tried to emulate the USA model by establishing Gateway Home Loans (Pty) Limited (Gateway) in 1999. Gateway, however, was not a success. This research investigates whether securitisation can be applied in South Africa to alleviate the low cost housing issue. The study finds that there is a credit availability gap for the low income sector earning less than R8 000 per month because of the perceived risk of default and unwillingness by banks to lend to this sector. The increase in housing backlog that continues unabated, inadequate housing finance system to low income earners, the lessons learnt from the failure of Gateway, the success factors of the USA securitisation model and the sound and sophisticated South African financial system are the rationale for applying securitisation. A proposal of how to effectively apply securitisation to low cost housing in South Africa is provided with recommendations to revive the primary market.
- Full Text:
- Date Issued: 2007
Segregated housing and contested identities: the case of the King William's Town coloured community, 1895 - 1946
- Authors: Victor, Stephanie Emilia
- Date: 2007
- Subjects: Colored people (South Africa) -- Race identity Colored people (South Africa) -- Political activity South Africa -- Race relations Colored people (South Africa) -- Housing Housing -- South Africa -- King William's Town Colored people (South Africa) -- Relocation Colored people (South Africa) -- South Africa -- King William's Town
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2568 , http://hdl.handle.net/10962/d1002421
- Description: This thesis is a case study of the dynamics of coloured housing in King William's Town between 1895 and 1946. The impact of spatial segregation on pre-apartheid coloured settlements in the Eastern Cape has largely been ignored up to the present. This needs to be rectified as the lack of in-depth enquiry can lead to misinterpretations that may influence contemporary politics and identity formation. Through research based on primary sources, it has become apparent that segregation in King William's Town was safeguarded and rationalized through the discourses of sanitation and civilization, and the practices of relocation and removal. The existing slum cond itions were used as a convenient excuse to implement municipal control. Segregation compounded the problem of poverty, inequitable access to housing and the provision of basic services. As a result, local coloured housing was increasingly characterised by a shortage of decent accommodation and basic services, decreasing home ownership and increasing municipal tenancy. In addition, through the implementation of the 1923 Natives (Urban Areas) Act and the 1934 Slums Act, high sanitation standards were set, but the Council itself provided inferior services. Ironically, conditions in the relocated municipal settlements were also not on par with the provisions stipulated in the Slums Act that were used to effect removal in the first place. The implementation of racially exclusive housing was, therefore, not driven by a single role player. It was pioneered by the local authorities, legalised by national government and supported by the coloured elite, when needed, in an attempt to access decent housing. This occurred mainly through the political manoeuvring of the coloured elite, and specifically the African Political (later People's) Organisation (APO), the Afrikaanse Nasionale Bond (AN B) and the locally constituted Coloured Welfare Association (CWA) in King William 's Town. These organisations attempted to procure access to housing within the narrow boundaries of a prescribed identity. Segregated housing therefore fostered and sustained coloured identity. It consolidated feelings of separateness and division and provided impetus for the construction of race and even racial tension. Coloured identity attempted to serve as a rallying point to overcome differences in religion, family and social networks and place of residence in order to procure access to housing. It was not, however, able to overcome the occasional division between settlements, caused by well-developed placeidentities, which still inform the contemporary housing milieu. The coloured elite initially did not question the legitimacy of coloured identity. Only in 1939, under threats of increased residential segregation, combined with the resulting opposition in coloured protest politics, was the legitimacy of coloured identity publicly contested . By 1943, with the creation of the Coloured Advisory Council (CAC), local coloured unity proved to be insufficient. A division within the ranks of the local coloured elite was evident. As a result, the expression of coloured identity still remains contested in contemporary King William's Town.
- Full Text:
- Date Issued: 2007
- Authors: Victor, Stephanie Emilia
- Date: 2007
- Subjects: Colored people (South Africa) -- Race identity Colored people (South Africa) -- Political activity South Africa -- Race relations Colored people (South Africa) -- Housing Housing -- South Africa -- King William's Town Colored people (South Africa) -- Relocation Colored people (South Africa) -- South Africa -- King William's Town
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2568 , http://hdl.handle.net/10962/d1002421
- Description: This thesis is a case study of the dynamics of coloured housing in King William's Town between 1895 and 1946. The impact of spatial segregation on pre-apartheid coloured settlements in the Eastern Cape has largely been ignored up to the present. This needs to be rectified as the lack of in-depth enquiry can lead to misinterpretations that may influence contemporary politics and identity formation. Through research based on primary sources, it has become apparent that segregation in King William's Town was safeguarded and rationalized through the discourses of sanitation and civilization, and the practices of relocation and removal. The existing slum cond itions were used as a convenient excuse to implement municipal control. Segregation compounded the problem of poverty, inequitable access to housing and the provision of basic services. As a result, local coloured housing was increasingly characterised by a shortage of decent accommodation and basic services, decreasing home ownership and increasing municipal tenancy. In addition, through the implementation of the 1923 Natives (Urban Areas) Act and the 1934 Slums Act, high sanitation standards were set, but the Council itself provided inferior services. Ironically, conditions in the relocated municipal settlements were also not on par with the provisions stipulated in the Slums Act that were used to effect removal in the first place. The implementation of racially exclusive housing was, therefore, not driven by a single role player. It was pioneered by the local authorities, legalised by national government and supported by the coloured elite, when needed, in an attempt to access decent housing. This occurred mainly through the political manoeuvring of the coloured elite, and specifically the African Political (later People's) Organisation (APO), the Afrikaanse Nasionale Bond (AN B) and the locally constituted Coloured Welfare Association (CWA) in King William 's Town. These organisations attempted to procure access to housing within the narrow boundaries of a prescribed identity. Segregated housing therefore fostered and sustained coloured identity. It consolidated feelings of separateness and division and provided impetus for the construction of race and even racial tension. Coloured identity attempted to serve as a rallying point to overcome differences in religion, family and social networks and place of residence in order to procure access to housing. It was not, however, able to overcome the occasional division between settlements, caused by well-developed placeidentities, which still inform the contemporary housing milieu. The coloured elite initially did not question the legitimacy of coloured identity. Only in 1939, under threats of increased residential segregation, combined with the resulting opposition in coloured protest politics, was the legitimacy of coloured identity publicly contested . By 1943, with the creation of the Coloured Advisory Council (CAC), local coloured unity proved to be insufficient. A division within the ranks of the local coloured elite was evident. As a result, the expression of coloured identity still remains contested in contemporary King William's Town.
- Full Text:
- Date Issued: 2007
Selecting stories to tell: the gatekeeping of international news at SAfm
- Authors: Ticha, Abel Akara
- Date: 2007
- Subjects: South African Broadcasting Corporation SAfm (South Africa) Radio broadcasting -- South Africa Foreign news -- South Africa Radio journalism -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3499 , http://hdl.handle.net/10962/d1004520
- Description: The premise of this thesis is that the selection of international news to be aired on the bulletins of SAfm by SABC Radio News staff is influenced by more complex factors than could be seen solely from the prism of an empirical journalistic paradigm. Drawing from data obtained through participant observation and interviewing, it is noted that there has been a revolution from a propagandist approach during apartheid to a professional approach following the demise of apartheid, in the selection of international news for bulletins on SAfm. Using Lewin's theory of forces in decision making and locating it within four out of five levels of a framework of gatekeeping analysis provided by Shoemaker (1991) and Shoemaker et al (200 I), it is concluded that the delimiting well-tested routines of newsmaking act as powerful companions of individuals' selection decisions of international news broadcast on SAfm's bulletins. However, these routines are adapted to meet the organisational demands of the SABC, which as a Public Service Broadcaster (PBS) has embraced the discourse of South African nationalism/panAfricanism, as a major philosophy underpinning the Corporation's coverage of the world. Therefore, some individual, routine and organisational factors influencing the se lection of international news broadcast on SAfm's bulletins, are predetermined and co-determined by the social system (the ideological/discursive structure), which is promoted by certain social institutions. Instances of spokespersons of such institutions as governments, international governmental and non-governmental organisations, etc., officiating the news abound; the gatekeepers use them to meet routine professional standards of journalism. This potentially works to sustain the hegemonic discourses of the powerful in international affairs (in tenns of core/peripheral nations relations, and elite classlruled majority relations) though there is a conscious oppositional effort to modify or dwarf stories that explicitly promote imperialism and to hold rulers accountable to the public. It is posited that the time is ripe for newsworkers responsible for the production of bulletins for SAfm to take the risk that may be necessary to inject a few changes in routine practices that could limit the engineering of consent to the powerful elites in the international arena.
- Full Text:
- Date Issued: 2007
- Authors: Ticha, Abel Akara
- Date: 2007
- Subjects: South African Broadcasting Corporation SAfm (South Africa) Radio broadcasting -- South Africa Foreign news -- South Africa Radio journalism -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3499 , http://hdl.handle.net/10962/d1004520
- Description: The premise of this thesis is that the selection of international news to be aired on the bulletins of SAfm by SABC Radio News staff is influenced by more complex factors than could be seen solely from the prism of an empirical journalistic paradigm. Drawing from data obtained through participant observation and interviewing, it is noted that there has been a revolution from a propagandist approach during apartheid to a professional approach following the demise of apartheid, in the selection of international news for bulletins on SAfm. Using Lewin's theory of forces in decision making and locating it within four out of five levels of a framework of gatekeeping analysis provided by Shoemaker (1991) and Shoemaker et al (200 I), it is concluded that the delimiting well-tested routines of newsmaking act as powerful companions of individuals' selection decisions of international news broadcast on SAfm's bulletins. However, these routines are adapted to meet the organisational demands of the SABC, which as a Public Service Broadcaster (PBS) has embraced the discourse of South African nationalism/panAfricanism, as a major philosophy underpinning the Corporation's coverage of the world. Therefore, some individual, routine and organisational factors influencing the se lection of international news broadcast on SAfm's bulletins, are predetermined and co-determined by the social system (the ideological/discursive structure), which is promoted by certain social institutions. Instances of spokespersons of such institutions as governments, international governmental and non-governmental organisations, etc., officiating the news abound; the gatekeepers use them to meet routine professional standards of journalism. This potentially works to sustain the hegemonic discourses of the powerful in international affairs (in tenns of core/peripheral nations relations, and elite classlruled majority relations) though there is a conscious oppositional effort to modify or dwarf stories that explicitly promote imperialism and to hold rulers accountable to the public. It is posited that the time is ripe for newsworkers responsible for the production of bulletins for SAfm to take the risk that may be necessary to inject a few changes in routine practices that could limit the engineering of consent to the powerful elites in the international arena.
- Full Text:
- Date Issued: 2007
Self-efficacy and the recognition of prior learning
- Authors: Rudman, Neville
- Date: 2007
- Subjects: Accreditation (Education) -- South Africa , Universities and colleges -- Accreditation -- South Africa , Experiential learning -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9536 , http://hdl.handle.net/10948/689 , Accreditation (Education) -- South Africa , Universities and colleges -- Accreditation -- South Africa , Experiential learning -- South Africa
- Description: The Recognition of Prior Learning (RPL), a mechanism grounded in the educational transformational policies of the African National Congress to redress the historical legacy of Apartheid, is a relatively new (and often contested) concept in South Africa. This research endeavors to investigate the effect of a module, which forms part of a B.Ed (upgrade) programme and is based on the processes and principles of RPL, on students’ (in-service teachers’) self-efficacy and their skills in terms of the development and execution of work schedules and lesson plans (the RPL-focus of the module). The methodology includes the gathering of quantitative and qualitative data through the administering of pre- and post- self-efficacy questionnaires, assessment of the portfolios of evidence produced by the students, and the feedback obtained from the focus-group interviews. The data indicate a statistically significant improvement in the participating students’ self-efficacy and draw attention to the negative issue of context in previously disadvantaged South African schools. The significance of this research lies not only in the interrogation of an innovative approach to dealing with RPL issues in an academic programme, and its possible influence on teacher self-efficacy, but also in its contribution to the academic debate about the RPL process which is currently taking place both locally and internationally.
- Full Text:
- Date Issued: 2007
- Authors: Rudman, Neville
- Date: 2007
- Subjects: Accreditation (Education) -- South Africa , Universities and colleges -- Accreditation -- South Africa , Experiential learning -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9536 , http://hdl.handle.net/10948/689 , Accreditation (Education) -- South Africa , Universities and colleges -- Accreditation -- South Africa , Experiential learning -- South Africa
- Description: The Recognition of Prior Learning (RPL), a mechanism grounded in the educational transformational policies of the African National Congress to redress the historical legacy of Apartheid, is a relatively new (and often contested) concept in South Africa. This research endeavors to investigate the effect of a module, which forms part of a B.Ed (upgrade) programme and is based on the processes and principles of RPL, on students’ (in-service teachers’) self-efficacy and their skills in terms of the development and execution of work schedules and lesson plans (the RPL-focus of the module). The methodology includes the gathering of quantitative and qualitative data through the administering of pre- and post- self-efficacy questionnaires, assessment of the portfolios of evidence produced by the students, and the feedback obtained from the focus-group interviews. The data indicate a statistically significant improvement in the participating students’ self-efficacy and draw attention to the negative issue of context in previously disadvantaged South African schools. The significance of this research lies not only in the interrogation of an innovative approach to dealing with RPL issues in an academic programme, and its possible influence on teacher self-efficacy, but also in its contribution to the academic debate about the RPL process which is currently taking place both locally and internationally.
- Full Text:
- Date Issued: 2007
Semiotics as a medium of analysis in selected poetic works of S.E.K. Mqhayi
- Authors: Mzinzi, Thanduxolo Samuel
- Date: 2007
- Subjects: Mqhayi, S. E. K. -- Criticism and interpretation , Poetry -- Analysis , Poetics , Semiotics
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8470 , http://hdl.handle.net/10948/576 , Mqhayi, S. E. K. -- Criticism and interpretation , Poetry -- Analysis , Poetics , Semiotics
- Description: In reference to Moleleki (1988:122), African poetry as a result of contrast rather than individual, is the representation of a community. This representation contains a scale of values based on the community, and it gives symbolic expression to the community: manifesting a community of tradition from the past through the present to the future. Going by the above notion, the poet assumes the responsibility of being the spokes-person of the community in which he/she finds and identifies himself/herself. He/she feels the pain felt by his/her people, and shares the joy shared by them. His/her representation therefore is both genuine and representatively expressive in nature. In the chosen poems of S. E. K. Mqhayi the above mentioned aspects of poetic writing are well expressed. This representation being a symbolic expression on behalf of the community holds a magnificent semiotic significance. Such semiotic significance, which boarders around the several highs and lows of the community’s lifestyle. The community poet in this context blends the past and the present in his verses attempting to both preserve and express the sorrows, the joys, the pains as well as the fears of his community and its people. These are captured in chapters three and four of this study. The community poet under the worst form of systematized inhuman, racist subjection called apartheid employed careful and skilful means of reciting as well as penning his verses. In the last four chapters one discovers a skilful means of masking in order to avoid being penalised. S.E.K Mqhayi’s element of symbolic expression is by far the most significant aspect of his poems. A man who lived in the days of abject institutionalised racism and being one of those discriminated against, had no choice but to be loyal to his oppressors and at the same time, expressing himself in the most creatively careful manner. His works are rich with encodings and embellishments. These encodings and embellishments require some careful skills to decode and unveil. This research work will centre mainly on the unravelling of all that was either encoded or embellished within each selected work.
- Full Text:
- Date Issued: 2007
- Authors: Mzinzi, Thanduxolo Samuel
- Date: 2007
- Subjects: Mqhayi, S. E. K. -- Criticism and interpretation , Poetry -- Analysis , Poetics , Semiotics
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8470 , http://hdl.handle.net/10948/576 , Mqhayi, S. E. K. -- Criticism and interpretation , Poetry -- Analysis , Poetics , Semiotics
- Description: In reference to Moleleki (1988:122), African poetry as a result of contrast rather than individual, is the representation of a community. This representation contains a scale of values based on the community, and it gives symbolic expression to the community: manifesting a community of tradition from the past through the present to the future. Going by the above notion, the poet assumes the responsibility of being the spokes-person of the community in which he/she finds and identifies himself/herself. He/she feels the pain felt by his/her people, and shares the joy shared by them. His/her representation therefore is both genuine and representatively expressive in nature. In the chosen poems of S. E. K. Mqhayi the above mentioned aspects of poetic writing are well expressed. This representation being a symbolic expression on behalf of the community holds a magnificent semiotic significance. Such semiotic significance, which boarders around the several highs and lows of the community’s lifestyle. The community poet in this context blends the past and the present in his verses attempting to both preserve and express the sorrows, the joys, the pains as well as the fears of his community and its people. These are captured in chapters three and four of this study. The community poet under the worst form of systematized inhuman, racist subjection called apartheid employed careful and skilful means of reciting as well as penning his verses. In the last four chapters one discovers a skilful means of masking in order to avoid being penalised. S.E.K Mqhayi’s element of symbolic expression is by far the most significant aspect of his poems. A man who lived in the days of abject institutionalised racism and being one of those discriminated against, had no choice but to be loyal to his oppressors and at the same time, expressing himself in the most creatively careful manner. His works are rich with encodings and embellishments. These encodings and embellishments require some careful skills to decode and unveil. This research work will centre mainly on the unravelling of all that was either encoded or embellished within each selected work.
- Full Text:
- Date Issued: 2007
Service provider's perceptions of the quality and accessiblity of health services under social health insurance in Dar-Es-Salaam
- Authors: Chomi, Eunice Nahyuha
- Date: 2007
- Subjects: Health insurance -- Tanzania , Medical personnel -- Insurance requirements -- Tanzania
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10079 , http://hdl.handle.net/10948/489 , Health insurance -- Tanzania , Medical personnel -- Insurance requirements -- Tanzania
- Description: Social health insurance is a form of health care financing that has gained increased attention in African countries in the past decade. Tanzania introduced social health insurance by the establishment of the National Health Insurance Fund (NHIF) in 1999 with, inter alia, the objective of improvement of the quality and availability of health services. The goal of this study was to determine the perceptions of services providers on the quality and accessibility of health services following the introduction of social health insurance. A qualitative approach was used to gain an insider's perspective from the service providers of how the services have changed following the introduction of the scheme. Individual interviews, observation and field notes were used to gather information on the quality and accessibility of health services under the policy of social health insurance. Data were analysed using Tesch's method of data analysis. The health workers generally perceived the fund as being beneficial to its members as it reduced the financial barriers to receiving health care. However, the objectives of the NHIF as a health financing mechanism were not adequately understood by the health workers. Although they perceived the quality of health services as having improved compared to previous years, they did not associate this improvement with the NHIF. The health workers also perceived accessibility of health services as having improved for insured patients but not for non-insured patients.
- Full Text:
- Date Issued: 2007
- Authors: Chomi, Eunice Nahyuha
- Date: 2007
- Subjects: Health insurance -- Tanzania , Medical personnel -- Insurance requirements -- Tanzania
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10079 , http://hdl.handle.net/10948/489 , Health insurance -- Tanzania , Medical personnel -- Insurance requirements -- Tanzania
- Description: Social health insurance is a form of health care financing that has gained increased attention in African countries in the past decade. Tanzania introduced social health insurance by the establishment of the National Health Insurance Fund (NHIF) in 1999 with, inter alia, the objective of improvement of the quality and availability of health services. The goal of this study was to determine the perceptions of services providers on the quality and accessibility of health services following the introduction of social health insurance. A qualitative approach was used to gain an insider's perspective from the service providers of how the services have changed following the introduction of the scheme. Individual interviews, observation and field notes were used to gather information on the quality and accessibility of health services under the policy of social health insurance. Data were analysed using Tesch's method of data analysis. The health workers generally perceived the fund as being beneficial to its members as it reduced the financial barriers to receiving health care. However, the objectives of the NHIF as a health financing mechanism were not adequately understood by the health workers. Although they perceived the quality of health services as having improved compared to previous years, they did not associate this improvement with the NHIF. The health workers also perceived accessibility of health services as having improved for insured patients but not for non-insured patients.
- Full Text:
- Date Issued: 2007
Social learning processes in a citrus farming community of practice
- Authors: Downsborough, Linda
- Date: 2007
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1878 , http://hdl.handle.net/10962/d1005859
- Description: Learning takes place in a number of ways. Situated learning for example, tries to shift the focus from the individual as a learner to the learner participating in the social world and from learning as a strictly cognitive process to a more encompassing view of social practice. The overall aim of this research was to gain a deeper understanding of the ways in which learning takes place in and between members of a citrus farming community, in other words it was to investigate the social learning processes. The research was undertaken in Patensie, a citrus farming community of the Gamtoos River Valley, Eastern Cape, South Africa. Data was generated through the use of interviews and informal discussions with participants together with document analysis, such as minutes of meetings. I also made observations of the learning interactions that were evident and also the interactions that were evident in the area as a whole. The data was analysed in two phases, the first involved reading across the interview transcripts and organizing the data under broad themes while the second phase made use of an analytical framework, a Community of Practice perspective to further analyze and engage with the data. I drew quite strongly on the ideas of situated learning, Communities of Practice and the notion of Legitimate Peripheral Participation (Lave & Wenger, 1991) as a means to understand, interpret and describe the social learning processes. The research highlighted that in this case study, citrus farmers learn in a number of sociological ways, for example through intergenerational learning (in the family), learning from each other in a Community of Practice, learning from private consultants and extensions officers as well as from other organizations and institutions. It also considered how farmers' learning had influenced land use practice in the area. This brought to the fore an emerging partnership with a conservation agent based on providing economic incentives to farmers to engage in sustainable landuse practices. It is hoped that this research may inform future educational endeavours by shedding light on the social learning processes and by drawing attention to key aspects of learning that may previously have been overlooked in research.
- Full Text:
- Date Issued: 2007
- Authors: Downsborough, Linda
- Date: 2007
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1878 , http://hdl.handle.net/10962/d1005859
- Description: Learning takes place in a number of ways. Situated learning for example, tries to shift the focus from the individual as a learner to the learner participating in the social world and from learning as a strictly cognitive process to a more encompassing view of social practice. The overall aim of this research was to gain a deeper understanding of the ways in which learning takes place in and between members of a citrus farming community, in other words it was to investigate the social learning processes. The research was undertaken in Patensie, a citrus farming community of the Gamtoos River Valley, Eastern Cape, South Africa. Data was generated through the use of interviews and informal discussions with participants together with document analysis, such as minutes of meetings. I also made observations of the learning interactions that were evident and also the interactions that were evident in the area as a whole. The data was analysed in two phases, the first involved reading across the interview transcripts and organizing the data under broad themes while the second phase made use of an analytical framework, a Community of Practice perspective to further analyze and engage with the data. I drew quite strongly on the ideas of situated learning, Communities of Practice and the notion of Legitimate Peripheral Participation (Lave & Wenger, 1991) as a means to understand, interpret and describe the social learning processes. The research highlighted that in this case study, citrus farmers learn in a number of sociological ways, for example through intergenerational learning (in the family), learning from each other in a Community of Practice, learning from private consultants and extensions officers as well as from other organizations and institutions. It also considered how farmers' learning had influenced land use practice in the area. This brought to the fore an emerging partnership with a conservation agent based on providing economic incentives to farmers to engage in sustainable landuse practices. It is hoped that this research may inform future educational endeavours by shedding light on the social learning processes and by drawing attention to key aspects of learning that may previously have been overlooked in research.
- Full Text:
- Date Issued: 2007
Social workers' experiences of HIV and AIDS intervention in Botswana
- Authors: Kesamang, Lefhoko
- Date: 2007
- Subjects: AIDS (Disease) -- Botswana , AIDS (Disease) -- Botswana -- Epidemiology , AIDS (Disease) -- Botswana -- Prevention
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9987 , http://hdl.handle.net/10948/532 , AIDS (Disease) -- Botswana , AIDS (Disease) -- Botswana -- Epidemiology , AIDS (Disease) -- Botswana -- Prevention
- Description: This study endeavoured to explore and describe the experiences of social workers in their intervention with HIV and AIDS clients within the Department of Clinical Services of the Ministry of Health in Botswana. The researcher undertook a qualitative research study, using an exploratory, descriptive and contextual design to explore these experiences as perceived by the social workers. The method of data collection included semi-structured face-to-face interviews, as this was deemed most appropriate to the nature of the study. Data analysis was undertaken according to the outline of Tesch (1990), as stated in Creswell (1994:155). The findings were reported as themes, sub-themes and categories emanating from the data-analysis process. In ensuring the trustworthiness of the findings, the researcher adhered to Guba’s (1981) model (in Krefting, 1991:251). The research findings were subjected to a literature control, and culminated in the compiling of the research report. The research findings centred around the following five themes: · experiences of intervention with HIV and AIDS clients; · challenges in HIV and AIDS intervention; · measures to alleviate challenges of HIV and AIDS intervention; · intervention strategies utilised by social workers; and · suggestions and advice to new social workers. The recommendations resulting from this research project proposed inter alia that social workers need to be trained in specific and specialised areas related to HIV and AIDS intervention in the health setting, and that the support structures and a holistic multidisciplinary service delivery approach need to be put in place to assist social workers to be able to meet the needs of the clients as well as their own needs. Key Words: participants, clients/patient, qualitative, HIV and AIDS, experiences, intervention, strategies.
- Full Text:
- Date Issued: 2007
- Authors: Kesamang, Lefhoko
- Date: 2007
- Subjects: AIDS (Disease) -- Botswana , AIDS (Disease) -- Botswana -- Epidemiology , AIDS (Disease) -- Botswana -- Prevention
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9987 , http://hdl.handle.net/10948/532 , AIDS (Disease) -- Botswana , AIDS (Disease) -- Botswana -- Epidemiology , AIDS (Disease) -- Botswana -- Prevention
- Description: This study endeavoured to explore and describe the experiences of social workers in their intervention with HIV and AIDS clients within the Department of Clinical Services of the Ministry of Health in Botswana. The researcher undertook a qualitative research study, using an exploratory, descriptive and contextual design to explore these experiences as perceived by the social workers. The method of data collection included semi-structured face-to-face interviews, as this was deemed most appropriate to the nature of the study. Data analysis was undertaken according to the outline of Tesch (1990), as stated in Creswell (1994:155). The findings were reported as themes, sub-themes and categories emanating from the data-analysis process. In ensuring the trustworthiness of the findings, the researcher adhered to Guba’s (1981) model (in Krefting, 1991:251). The research findings were subjected to a literature control, and culminated in the compiling of the research report. The research findings centred around the following five themes: · experiences of intervention with HIV and AIDS clients; · challenges in HIV and AIDS intervention; · measures to alleviate challenges of HIV and AIDS intervention; · intervention strategies utilised by social workers; and · suggestions and advice to new social workers. The recommendations resulting from this research project proposed inter alia that social workers need to be trained in specific and specialised areas related to HIV and AIDS intervention in the health setting, and that the support structures and a holistic multidisciplinary service delivery approach need to be put in place to assist social workers to be able to meet the needs of the clients as well as their own needs. Key Words: participants, clients/patient, qualitative, HIV and AIDS, experiences, intervention, strategies.
- Full Text:
- Date Issued: 2007
Social workers' experiences on the transformation of social welfare from a remedial approach to a developmental approach
- Authors: Mashigo, Boipuso Stephina
- Date: 2007
- Subjects: Social service -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9990 , http://hdl.handle.net/10948/559 , Social service -- South Africa
- Description: When the new democratic government came into power, much legislation, policies and strategies were transformed, included was the welfare system that was imbalanced, unjust, discriminatory and inappropriate. It was replaced by a developmental approach that is more just, equitable and appropriate system contained in the White Paper for Social Welfare (1997). Social workers were expected to reform their method of intervention. Consequently, this study will focus on the experiences of social workers as changes were brought into the approaches used in service delivery. The goal of the study is to explore and describe social workers’ experiences on the transformation of social welfare from a traditional remedial approach to a developmental approach. The study was conducted using the qualitative research approach. The research study made use of an explorative, descriptive and contextual design. The researcher used purposive and theoretical non-probability sampling methods to draw the sample. Data was collected through semi- structured interviews. The data was analyzed using Tesch’s eight steps in Creswell (1994:155) and was verified against four criteria that Guba in (Krefting, 1991) developed for testing the trustworthiness of a qualitative study. Based on the findings and conclusion of the study, recommendations were made to the management of the department of social development on how to address the challenges facing social workers on the implementation of the developmental approach. The results will be disseminated by means of a written research report.
- Full Text:
- Date Issued: 2007
- Authors: Mashigo, Boipuso Stephina
- Date: 2007
- Subjects: Social service -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9990 , http://hdl.handle.net/10948/559 , Social service -- South Africa
- Description: When the new democratic government came into power, much legislation, policies and strategies were transformed, included was the welfare system that was imbalanced, unjust, discriminatory and inappropriate. It was replaced by a developmental approach that is more just, equitable and appropriate system contained in the White Paper for Social Welfare (1997). Social workers were expected to reform their method of intervention. Consequently, this study will focus on the experiences of social workers as changes were brought into the approaches used in service delivery. The goal of the study is to explore and describe social workers’ experiences on the transformation of social welfare from a traditional remedial approach to a developmental approach. The study was conducted using the qualitative research approach. The research study made use of an explorative, descriptive and contextual design. The researcher used purposive and theoretical non-probability sampling methods to draw the sample. Data was collected through semi- structured interviews. The data was analyzed using Tesch’s eight steps in Creswell (1994:155) and was verified against four criteria that Guba in (Krefting, 1991) developed for testing the trustworthiness of a qualitative study. Based on the findings and conclusion of the study, recommendations were made to the management of the department of social development on how to address the challenges facing social workers on the implementation of the developmental approach. The results will be disseminated by means of a written research report.
- Full Text:
- Date Issued: 2007
Stakeholders' perceptions of parents' involvement in the governance of a Namibian rural school
- Authors: Niitembu, Martha M
- Date: 2007
- Subjects: School management and organization -- Namibia Education -- Parent participation -- Namibia Education and state -- Namibia Rural schools -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1770 , http://hdl.handle.net/10962/d1003655
- Description: The issue of decentralisation has been one of the top priorities of the Namibian education system since independence in 1990. One of the decentralisation aims was to enhance parental involvement in education by establishing School Boards. However, School Boards and the role of parents in school management have been considered ineffective for several years which led to the promulgation of Education Act 16 of 2001 in which the roles of School Boards are strengthened and clarified. This study sought to investigate School Board members’ perceptions, understanding and experiences of parents’ involvement in school governance more specifically after the implementation of the Education Act of 2001 in 2003. This study is an interpretive case study of one combined rural school in the Ohangwena educational region of Namibia. This research employed three data collection techniques, namely semi-structured interviews, observation and document analysis. The main findings of this study reveal that there is a lack of joint understanding and shared vision between educators and parents in the School Board. This problem underpins other more symptomatic problems, such as lack of accountability in the matter of school finances, differences in understanding the roles of School Board members and lack of parents’ motivation from the school management. The study further reveals the ineffectiveness and insufficiency of the training provided in the past. It highlights some of the challenges that hinder the effective involvement of parents in rural school governance, such as poor educational background among parents, poor knowledge of the English language and poor understanding of educational issues. However the findings also acknowledge parents’ participation and their full involvement in decision-making. The findings show that the new School Board elected in terms of the Education Act of 2001 has been more effective than previous School Boards and has reached a number of achievements such as being instrumental in solving disciplinary problems, purchasing school assets and renovating classrooms. Recommendations for practice and for further research are made.
- Full Text:
- Date Issued: 2007
- Authors: Niitembu, Martha M
- Date: 2007
- Subjects: School management and organization -- Namibia Education -- Parent participation -- Namibia Education and state -- Namibia Rural schools -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1770 , http://hdl.handle.net/10962/d1003655
- Description: The issue of decentralisation has been one of the top priorities of the Namibian education system since independence in 1990. One of the decentralisation aims was to enhance parental involvement in education by establishing School Boards. However, School Boards and the role of parents in school management have been considered ineffective for several years which led to the promulgation of Education Act 16 of 2001 in which the roles of School Boards are strengthened and clarified. This study sought to investigate School Board members’ perceptions, understanding and experiences of parents’ involvement in school governance more specifically after the implementation of the Education Act of 2001 in 2003. This study is an interpretive case study of one combined rural school in the Ohangwena educational region of Namibia. This research employed three data collection techniques, namely semi-structured interviews, observation and document analysis. The main findings of this study reveal that there is a lack of joint understanding and shared vision between educators and parents in the School Board. This problem underpins other more symptomatic problems, such as lack of accountability in the matter of school finances, differences in understanding the roles of School Board members and lack of parents’ motivation from the school management. The study further reveals the ineffectiveness and insufficiency of the training provided in the past. It highlights some of the challenges that hinder the effective involvement of parents in rural school governance, such as poor educational background among parents, poor knowledge of the English language and poor understanding of educational issues. However the findings also acknowledge parents’ participation and their full involvement in decision-making. The findings show that the new School Board elected in terms of the Education Act of 2001 has been more effective than previous School Boards and has reached a number of achievements such as being instrumental in solving disciplinary problems, purchasing school assets and renovating classrooms. Recommendations for practice and for further research are made.
- Full Text:
- Date Issued: 2007
Statistical analyses of artificial waterpoints: their effect on the herbaceous and woody structure composition within the Kruger National Park
- Authors: Goodall, Victoria Lucy
- Date: 2007
- Subjects: South African National Parks , Ecology -- Statistical methods , Regression analysis , Log-linear models , Game reserves -- South Africa , Kruger National Park (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5570 , http://hdl.handle.net/10962/d1002810 , South African National Parks , Ecology -- Statistical methods , Regression analysis , Log-linear models , Game reserves -- South Africa , Kruger National Park (South Africa)
- Description: The objective of this project is to link the statistical theory used in the ecological sciences with an actual project that was developed for the South African National Parks Scientific Services. It investigates the changes that have occurred in the herbaceous and woody structure due to the closure of artificial waterpoints; including the impacts that elephants and other herbivores have on the vegetation of the Kruger National Park. This project was designed in conjunction with South African National Parks (SANP) Scientific Services and it is a registered project with this department. The results of this project will be submitted to Scientific Services in accordance with the terms and conditions of a SANP research project. A major concern within the KNP is the declining numbers of rare antelope and numerous projects have been developed to investigate possible ways of halting this decline and thus protecting the heterogeneity of the Kruger National Park. Three different datasets were investigated, covering three aspects of vegetation structure and composition within the KNP. The first investigated the changes that have occurred since the N'washitsumbe enclosure in the Far Northern KNP was fenced off from the rest of the park. The results show that over the 40 years since the enclosure was built, changes have occurred which have resulted in a significant difference in the abundance of Increaser 2 and Decreaser grass species between the inside and the outside of the enclosure. Increaser 2 and Decreaser categories are the result of a grass species classification depending on whether the species thrives or is depressed by heavy grazing. The difference in grass species composition and structure between the inside and the outside of the enclosure indicates that the grazing animals within the KNP have influenced the grass composition in a way that favours the dominant animals. This has resulted in a declining roan antelope population - one of the species that is considered as a 'rare antelope'. Many artificial waterpoints (boreholes and dams) have also been closed throughout the KNP in the hope of resulting in a change in vegetation structure and composition in favour of the roan. Veld condition assessment data for 87 boreholes throughout the Park was analyzed to determine whether the veld in the vicinity is beginning to change towards a more Decreaser dominated sward which would favour the roan. The results were analyzed for the different regions of the Park; and they indicate that changes are becoming evident; however, the results are not particularly conclusive, yet. The majority of the boreholes were closed between 1994 and 1998 which means that not a lot of data were available to be analyzed. A similar study conducted in another 10 years time might reveal more meaningful results. However the results are moving in the direction hoped for by the management of the KNP. The results show that the grass composition has a higher proportion of Decreaser grasses since the closure of the waterpoints, and the grass biomass around these areas has also improved. The results were analyzed on an individual basis; and then on a regional basis as the minimal data meant that the individual analyses did not provide any significant results. A third study was then done on the impact that the rapidly increasing elephant population on the vegetation within the Riparian zone along three rivers in the Far Northern region of the KNP. The riparian zone is an important part of the landscape, in terms of providing food for many animals as well as shade. The elephant population has increased substantially since the termination of the culling program and this means that the feeding requirements of the population has increased which could result in severe damage upon the vegetation, as elephants can be very destructive feeders. The results show surprising differences between the three years of data that were analyzed; however the results indicate that the elephants are targeting specific height ranges of trees when feeding; however they do not seem to consistently target specific tree species. This is positive for the diversity of the Riparian zone as this region is very important both ecologically and aesthetically for the tourists who visit the Park.
- Full Text:
- Date Issued: 2007
- Authors: Goodall, Victoria Lucy
- Date: 2007
- Subjects: South African National Parks , Ecology -- Statistical methods , Regression analysis , Log-linear models , Game reserves -- South Africa , Kruger National Park (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5570 , http://hdl.handle.net/10962/d1002810 , South African National Parks , Ecology -- Statistical methods , Regression analysis , Log-linear models , Game reserves -- South Africa , Kruger National Park (South Africa)
- Description: The objective of this project is to link the statistical theory used in the ecological sciences with an actual project that was developed for the South African National Parks Scientific Services. It investigates the changes that have occurred in the herbaceous and woody structure due to the closure of artificial waterpoints; including the impacts that elephants and other herbivores have on the vegetation of the Kruger National Park. This project was designed in conjunction with South African National Parks (SANP) Scientific Services and it is a registered project with this department. The results of this project will be submitted to Scientific Services in accordance with the terms and conditions of a SANP research project. A major concern within the KNP is the declining numbers of rare antelope and numerous projects have been developed to investigate possible ways of halting this decline and thus protecting the heterogeneity of the Kruger National Park. Three different datasets were investigated, covering three aspects of vegetation structure and composition within the KNP. The first investigated the changes that have occurred since the N'washitsumbe enclosure in the Far Northern KNP was fenced off from the rest of the park. The results show that over the 40 years since the enclosure was built, changes have occurred which have resulted in a significant difference in the abundance of Increaser 2 and Decreaser grass species between the inside and the outside of the enclosure. Increaser 2 and Decreaser categories are the result of a grass species classification depending on whether the species thrives or is depressed by heavy grazing. The difference in grass species composition and structure between the inside and the outside of the enclosure indicates that the grazing animals within the KNP have influenced the grass composition in a way that favours the dominant animals. This has resulted in a declining roan antelope population - one of the species that is considered as a 'rare antelope'. Many artificial waterpoints (boreholes and dams) have also been closed throughout the KNP in the hope of resulting in a change in vegetation structure and composition in favour of the roan. Veld condition assessment data for 87 boreholes throughout the Park was analyzed to determine whether the veld in the vicinity is beginning to change towards a more Decreaser dominated sward which would favour the roan. The results were analyzed for the different regions of the Park; and they indicate that changes are becoming evident; however, the results are not particularly conclusive, yet. The majority of the boreholes were closed between 1994 and 1998 which means that not a lot of data were available to be analyzed. A similar study conducted in another 10 years time might reveal more meaningful results. However the results are moving in the direction hoped for by the management of the KNP. The results show that the grass composition has a higher proportion of Decreaser grasses since the closure of the waterpoints, and the grass biomass around these areas has also improved. The results were analyzed on an individual basis; and then on a regional basis as the minimal data meant that the individual analyses did not provide any significant results. A third study was then done on the impact that the rapidly increasing elephant population on the vegetation within the Riparian zone along three rivers in the Far Northern region of the KNP. The riparian zone is an important part of the landscape, in terms of providing food for many animals as well as shade. The elephant population has increased substantially since the termination of the culling program and this means that the feeding requirements of the population has increased which could result in severe damage upon the vegetation, as elephants can be very destructive feeders. The results show surprising differences between the three years of data that were analyzed; however the results indicate that the elephants are targeting specific height ranges of trees when feeding; however they do not seem to consistently target specific tree species. This is positive for the diversity of the Riparian zone as this region is very important both ecologically and aesthetically for the tourists who visit the Park.
- Full Text:
- Date Issued: 2007
Strategies for managing work related stress
- Authors: Müller, Elsie Franscina
- Date: 2007
- Subjects: Stress management , Job stress , Work -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8577 , http://hdl.handle.net/10948/742 , Stress management , Job stress , Work -- Psychological aspects
- Description: The objective of this study was to identify the strategies (primary, secondary and tertiary) that can be employed to manage work related stress. A questionnaire, was designed based on the strategies found in a literature study on the topic and used to gather inputs from academic head of department and lecturers. The questionnaire was delivered by hand to 18 potential respondents. All 16 questionnaires returned could be used. These were processed and analysed using Microsoft Excel spreadsheets. In general support was found for primary stress management strategies pertaining to work schedule, work load and work pace, job content, career development, the home-work relationship and work environment. Lifestyle management in terms of physical activities and a healthy diet were regarded as the preferred secondary stress management strategies. The strategies related to lifestyle management which were identified from the literature study were physical activities, healthy diet, relaxation techniques such as meditation and yoga. Support was found for tertiary stress management strategies but most of the respondents were not sure if their organisation offered any wellness, employee assistance or stress management programmes. Wellness programmes were indicated as a strategy that will have the most impact on reducing work related stress and employee assistance programmes (EAPs) ranked there after. Overall respondents indicated that they did not perceive their work as very stressful.
- Full Text:
- Date Issued: 2007
- Authors: Müller, Elsie Franscina
- Date: 2007
- Subjects: Stress management , Job stress , Work -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8577 , http://hdl.handle.net/10948/742 , Stress management , Job stress , Work -- Psychological aspects
- Description: The objective of this study was to identify the strategies (primary, secondary and tertiary) that can be employed to manage work related stress. A questionnaire, was designed based on the strategies found in a literature study on the topic and used to gather inputs from academic head of department and lecturers. The questionnaire was delivered by hand to 18 potential respondents. All 16 questionnaires returned could be used. These were processed and analysed using Microsoft Excel spreadsheets. In general support was found for primary stress management strategies pertaining to work schedule, work load and work pace, job content, career development, the home-work relationship and work environment. Lifestyle management in terms of physical activities and a healthy diet were regarded as the preferred secondary stress management strategies. The strategies related to lifestyle management which were identified from the literature study were physical activities, healthy diet, relaxation techniques such as meditation and yoga. Support was found for tertiary stress management strategies but most of the respondents were not sure if their organisation offered any wellness, employee assistance or stress management programmes. Wellness programmes were indicated as a strategy that will have the most impact on reducing work related stress and employee assistance programmes (EAPs) ranked there after. Overall respondents indicated that they did not perceive their work as very stressful.
- Full Text:
- Date Issued: 2007
Studies towards the development of novel multidentate ligands
- Authors: Magqi, Nceba
- Date: 2007
- Subjects: Density functionals , Ligands , Ligands -- Design , Ligands -- Analysis , Camphor
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4358 , http://hdl.handle.net/10962/d1005023 , Density functionals , Ligands , Ligands -- Design , Ligands -- Analysis , Camphor
- Description: In this study, attention has been given to the design and synthesis of novel multidentate ligands for use in the construction of ruthenium-based metathesis catalysts, and their chelating potential has been explored by computer modelling at the Density Functional Theory (DFT) level. Both Kemp’s triacid (1,3,5-trimethyl-1,3,5-cyclohexanetricarboxylic acid) and D-(+)-camphor have been investigated as molecular scaffolds for the development of such ligands. However selective elaboration of the functional groups in Kemp’s triacid proved difficult to achieve, and the research has focused on the development of camphor derivatives. The synthesis of the camphor-based ligands has involved C-8 functionalisation and ring-opening of the bicyclic system to afford tridentate products. The formation of 9-iodocamphorquinone bis(ethylene ketal) together with the desired product, the 8-iodo isomer, has been confirmed by single crystal X-ray analysis of both compounds. Formation of the 9-iodo analogue has provided new insights into the intramolecular rearrangement of camphor skeleton, and the mechanistic implications have been assessed by coset analysis. Attempts to effect nucleophilic displacement of the 8-halogeno groups by nucleophilic donor moieties proved unexpectedly difficult and, coupled with the susceptibility of the carbonyl groups to nucleophilic attack, has led to the formation of novel tricyclic products, viz., 1,6-dimethyl-3-(2-pyridylamino)-4-oxatricyclo[4.3.0.0[superscript 3,7]]-2-nonanone and 6,7-dimethyl-3-(2-pyridylamino)-4-oxatricyclo -[4.3.0.0[superscript 3,7]]-2-nonanone. However the diphenylphosphine group was successfully introduced at C-8 and oxidative ring-opening of the camphor skeleton has afforded the tridentate ligands, 2-(diphenylphosphinoylmethyl)-1,2-dimethyl-1,3-cyclopentanedicarboxylic acid and 2-(diphenylphosphinoylmethyl)-1,3-bis(hydroxymethyl)1,2-dimethylcyclopentane. One- and two-dimensional NMR and, where appropriate, high-resolution MS methods have been used to characterise the products. Three [superscript 13]C NMR chemical shift prediction programmes, viz., ChemWindow and the MODGRAPH neural network and HOSE (Hierachially Ordered Spherical description of Environment), have been applied to representative compounds to assess their efficacy. While the predicted shifts correlated reasonably well with the experimental data, they proved to be insufficiently accurate to differentiate the isomeric systems examined.
- Full Text:
- Date Issued: 2007
- Authors: Magqi, Nceba
- Date: 2007
- Subjects: Density functionals , Ligands , Ligands -- Design , Ligands -- Analysis , Camphor
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4358 , http://hdl.handle.net/10962/d1005023 , Density functionals , Ligands , Ligands -- Design , Ligands -- Analysis , Camphor
- Description: In this study, attention has been given to the design and synthesis of novel multidentate ligands for use in the construction of ruthenium-based metathesis catalysts, and their chelating potential has been explored by computer modelling at the Density Functional Theory (DFT) level. Both Kemp’s triacid (1,3,5-trimethyl-1,3,5-cyclohexanetricarboxylic acid) and D-(+)-camphor have been investigated as molecular scaffolds for the development of such ligands. However selective elaboration of the functional groups in Kemp’s triacid proved difficult to achieve, and the research has focused on the development of camphor derivatives. The synthesis of the camphor-based ligands has involved C-8 functionalisation and ring-opening of the bicyclic system to afford tridentate products. The formation of 9-iodocamphorquinone bis(ethylene ketal) together with the desired product, the 8-iodo isomer, has been confirmed by single crystal X-ray analysis of both compounds. Formation of the 9-iodo analogue has provided new insights into the intramolecular rearrangement of camphor skeleton, and the mechanistic implications have been assessed by coset analysis. Attempts to effect nucleophilic displacement of the 8-halogeno groups by nucleophilic donor moieties proved unexpectedly difficult and, coupled with the susceptibility of the carbonyl groups to nucleophilic attack, has led to the formation of novel tricyclic products, viz., 1,6-dimethyl-3-(2-pyridylamino)-4-oxatricyclo[4.3.0.0[superscript 3,7]]-2-nonanone and 6,7-dimethyl-3-(2-pyridylamino)-4-oxatricyclo -[4.3.0.0[superscript 3,7]]-2-nonanone. However the diphenylphosphine group was successfully introduced at C-8 and oxidative ring-opening of the camphor skeleton has afforded the tridentate ligands, 2-(diphenylphosphinoylmethyl)-1,2-dimethyl-1,3-cyclopentanedicarboxylic acid and 2-(diphenylphosphinoylmethyl)-1,3-bis(hydroxymethyl)1,2-dimethylcyclopentane. One- and two-dimensional NMR and, where appropriate, high-resolution MS methods have been used to characterise the products. Three [superscript 13]C NMR chemical shift prediction programmes, viz., ChemWindow and the MODGRAPH neural network and HOSE (Hierachially Ordered Spherical description of Environment), have been applied to representative compounds to assess their efficacy. While the predicted shifts correlated reasonably well with the experimental data, they proved to be insufficiently accurate to differentiate the isomeric systems examined.
- Full Text:
- Date Issued: 2007
Study of metallophthalocyanines attached onto pre-modified gold surfaces
- Authors: Mashazi, Philani Nkosinathi
- Date: 2007
- Subjects: Phthalocyanines , Electrochemistry , Electrodes, Enzyme , Glucose -- Measurement
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4361 , http://hdl.handle.net/10962/d1005026 , Phthalocyanines , Electrochemistry , Electrodes, Enzyme , Glucose -- Measurement
- Description: Tetra-carboxy acid chloride phthalocyanine complexes of cobalt, iron and manganese were synthesized and characterized using spectroscopic and electrochemical techniques. These complexes were fabricated as thin films on gold electrode following a covalent immobilization and self-assembling methods. Surface electrochemical and spectroscopic characterization showed that these complexes are surface-confined species. The characterization using spectroscopic and electrochemical methods confirmed the formation of thiol and MPc SAMs on gold electrode. The electrocatalytic behaviour of the SAM modified gold electrodes was studied for the detection of L-cysteine and hydrogen peroxide. The limits of detection (LoD) for Lcysteine were of the orders of 10[superscript -7] mol.L[superscript -1] for all the MPc complexes studied and the LoD for hydrogen peroxide at cobalt phthalocyanine modified gold electrode was of the orders of 10[superscript -7]mol.L[superscript -1] for both electrocatalytic oxidation and reduction. The modification process for gold electrodes was reproducible and showed good stability, if stored in pH 4 phosphate buffer solutions and can be used over a long period of time. The cobalt phthalocyanine modified gold electrode was also investigated for the fabrication of glucose oxidase (GOx)-based biosensor and as an electron mediator between the enzyme and gold electrode. The behaviour of the enzyme modified gold electrode towards the detection of glucose was studied and the results gave a limit of detection of the orders of 10[superscript -6] mol.L[superscript -1] with low binding constant (4.8 mM) of enzyme (GOx) to substrate (glucose) referred to as Michaelis-Menten constant. The practical applications, i.e. the real sample analysis and interference studies, for the enzyme modified gold electrodes were investigated. These studies showed that the enzyme electrode is valuable and can be used for glucose detection.
- Full Text:
- Date Issued: 2007
- Authors: Mashazi, Philani Nkosinathi
- Date: 2007
- Subjects: Phthalocyanines , Electrochemistry , Electrodes, Enzyme , Glucose -- Measurement
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4361 , http://hdl.handle.net/10962/d1005026 , Phthalocyanines , Electrochemistry , Electrodes, Enzyme , Glucose -- Measurement
- Description: Tetra-carboxy acid chloride phthalocyanine complexes of cobalt, iron and manganese were synthesized and characterized using spectroscopic and electrochemical techniques. These complexes were fabricated as thin films on gold electrode following a covalent immobilization and self-assembling methods. Surface electrochemical and spectroscopic characterization showed that these complexes are surface-confined species. The characterization using spectroscopic and electrochemical methods confirmed the formation of thiol and MPc SAMs on gold electrode. The electrocatalytic behaviour of the SAM modified gold electrodes was studied for the detection of L-cysteine and hydrogen peroxide. The limits of detection (LoD) for Lcysteine were of the orders of 10[superscript -7] mol.L[superscript -1] for all the MPc complexes studied and the LoD for hydrogen peroxide at cobalt phthalocyanine modified gold electrode was of the orders of 10[superscript -7]mol.L[superscript -1] for both electrocatalytic oxidation and reduction. The modification process for gold electrodes was reproducible and showed good stability, if stored in pH 4 phosphate buffer solutions and can be used over a long period of time. The cobalt phthalocyanine modified gold electrode was also investigated for the fabrication of glucose oxidase (GOx)-based biosensor and as an electron mediator between the enzyme and gold electrode. The behaviour of the enzyme modified gold electrode towards the detection of glucose was studied and the results gave a limit of detection of the orders of 10[superscript -6] mol.L[superscript -1] with low binding constant (4.8 mM) of enzyme (GOx) to substrate (glucose) referred to as Michaelis-Menten constant. The practical applications, i.e. the real sample analysis and interference studies, for the enzyme modified gold electrodes were investigated. These studies showed that the enzyme electrode is valuable and can be used for glucose detection.
- Full Text:
- Date Issued: 2007
Subtle racism amongst undergraduate learners after a decade of democracy
- Authors: Van der Westhuizen, Amanda
- Date: 2007
- Subjects: Racism in higher education -- South Africa -- Nelson Mandela Bay , Intergroup relations , Social interaction
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9954 , http://hdl.handle.net/10948/d1018820
- Description: The concept of “race” has been the organising feature of South African society for more than three centuries. More recent social changes in the United States of America, Europe, Australia, and South Africa have lead to more subtle expressions of racism. The present study aimed to explore and describe subtle racism amongst undergraduate psychology learners at a tertiary institution in Nelson Mandela Metropolitan Municipality in 2004. The Subtle Racism Scale was used to measure anti-Black sentiment among a sample of 286 undergraduate psychology learners, obtained through non–probability, convenience sampling. Multiple regression analysis revealed the independent variables of race, age, and the race-age interaction were significantly associated with subtle racism of the participants. Research results demonstrated that participants’ level of estimated subtle racism varied according to the age and race of the participants, supporting the notion that racism in South Africa did not influence different age and race groups in a uniform manner.
- Full Text:
- Date Issued: 2007
- Authors: Van der Westhuizen, Amanda
- Date: 2007
- Subjects: Racism in higher education -- South Africa -- Nelson Mandela Bay , Intergroup relations , Social interaction
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9954 , http://hdl.handle.net/10948/d1018820
- Description: The concept of “race” has been the organising feature of South African society for more than three centuries. More recent social changes in the United States of America, Europe, Australia, and South Africa have lead to more subtle expressions of racism. The present study aimed to explore and describe subtle racism amongst undergraduate psychology learners at a tertiary institution in Nelson Mandela Metropolitan Municipality in 2004. The Subtle Racism Scale was used to measure anti-Black sentiment among a sample of 286 undergraduate psychology learners, obtained through non–probability, convenience sampling. Multiple regression analysis revealed the independent variables of race, age, and the race-age interaction were significantly associated with subtle racism of the participants. Research results demonstrated that participants’ level of estimated subtle racism varied according to the age and race of the participants, supporting the notion that racism in South Africa did not influence different age and race groups in a uniform manner.
- Full Text:
- Date Issued: 2007
Synthesis and characterization of symmetrical and unsymmetrical ferrocenyl ligands for use in the preparation of Redox Active Ruthenium Alkylidene Complexes
- Authors: Saku, Duduetsang
- Date: 2007
- Subjects: Ferrocene , Ligands , Asymmetric synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10403 , http://hdl.handle.net/10948/701 , Ferrocene , Ligands , Asymmetric synthesis
- Description: Oxidation of a ferrocenyl group in conjugation to another metal centre can alter the electron density at that metal centre and lead to a change in overall reactivity of a complex. Herein, the synthesis and characterization of redox active symmetrical and unsymmetrical ferrocenylalkene derivatives is described. A change in the standard redox potential of ferrocene (465 mV), to more positive potentials in vinylferrocene 1 (478 mV) and 4-phenylvinylferrocene 3 (499 mV), showed how manipulation of a redox potential can be effected on the ferrocenyl moiety by just using conjugation effects. A shift by +13 mV is observed in 1 and this potential more than doubled in 3 (+34 mV). Ferrocenylderived ruthenium alkylidene complexes were also prepared in a cross metathesis of 1 and 3 with Grubbs’ 1 (676.5 mV) to give complexes Ferrocenylidenebis( tricyclohexylphosphine)dichlororuthenium 14, 4-ferrocenylphenylidene-bis (tricyclohexylphosphine)dichlororuthenium 15 respectively. The extent of the electronic communication between the ferrocenyl group and the ruthenium centre was then estimated by looking at the positive or negative redox potential shifts of 14 and 15 as a result of 1 and 3. A large positive potential shift by 180 mV in 14 indicated that there was a strong electronic communication between the two metal centres, while the smaller, yet significant positive potential shift by 89.5 mV in 15 showed 3 to have a lesser effect on the ruthenium centre. Compounds 14 and 15 were tested in a Ring Closing Metathesis (RCM) of diethyldiallylmalonate showed enhanced reactivity.
- Full Text:
- Date Issued: 2007
- Authors: Saku, Duduetsang
- Date: 2007
- Subjects: Ferrocene , Ligands , Asymmetric synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10403 , http://hdl.handle.net/10948/701 , Ferrocene , Ligands , Asymmetric synthesis
- Description: Oxidation of a ferrocenyl group in conjugation to another metal centre can alter the electron density at that metal centre and lead to a change in overall reactivity of a complex. Herein, the synthesis and characterization of redox active symmetrical and unsymmetrical ferrocenylalkene derivatives is described. A change in the standard redox potential of ferrocene (465 mV), to more positive potentials in vinylferrocene 1 (478 mV) and 4-phenylvinylferrocene 3 (499 mV), showed how manipulation of a redox potential can be effected on the ferrocenyl moiety by just using conjugation effects. A shift by +13 mV is observed in 1 and this potential more than doubled in 3 (+34 mV). Ferrocenylderived ruthenium alkylidene complexes were also prepared in a cross metathesis of 1 and 3 with Grubbs’ 1 (676.5 mV) to give complexes Ferrocenylidenebis( tricyclohexylphosphine)dichlororuthenium 14, 4-ferrocenylphenylidene-bis (tricyclohexylphosphine)dichlororuthenium 15 respectively. The extent of the electronic communication between the ferrocenyl group and the ruthenium centre was then estimated by looking at the positive or negative redox potential shifts of 14 and 15 as a result of 1 and 3. A large positive potential shift by 180 mV in 14 indicated that there was a strong electronic communication between the two metal centres, while the smaller, yet significant positive potential shift by 89.5 mV in 15 showed 3 to have a lesser effect on the ruthenium centre. Compounds 14 and 15 were tested in a Ring Closing Metathesis (RCM) of diethyldiallylmalonate showed enhanced reactivity.
- Full Text:
- Date Issued: 2007
Synthesis of novel coumarin derivatives as potential inhibitors of HIV-1 protease
- Authors: Rose, Nathan Rolf
- Date: 2007 , 2013-07-01
- Subjects: Coumarins , Protease Inhibitors , Heterocyclic compounds -- Derivatives , HIV infections -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4430 , http://hdl.handle.net/10962/d1007220 , Coumarins , Protease Inhibitors , Heterocyclic compounds -- Derivatives , HIV infections -- Treatment
- Description: This research has focused on the development of novel coumann derivatives containing peptide-like side chains as potential HIV-1 protease inhibitors. The reaction of various salicylaldehyde derivatives with tert-butyl acrylate In the presence of 1,4- diazabicyclo[2.2.2]octane (DABCO) has afforded a series of Baylis-Hillman adducts in moderate yield. Cyclisation of the adducts in the presence of HCI afforded the corresponding 3-(chloromethyl)coumarin derivatives, which have been reacted with various amine hydrochlorides in the presence of Proton Sponge® to afford a series of novel 3- (aminomethyl)coumarin derivatives, which were fully characterised by NMR and HRMS methods. Various approaches to the introduction of hydroxyl or amino groups at the C-4 position of coumarin and the 3-(chloromethyl)coumarin derivatives have been explored; these have included dihydroxylation of the coumarin double bond, and the synthesis of 4- benzylaminocoumarin derivatives as potential intermediates. The Vilsmeier-Haack and Mannich reactions have also been investigated as possible methods of introducing the desired peptide-like functionality. Computer modelling of selected structures has indicated that some of the novel 3- (aminomethyl)coumarin derivatives may exhibit activity as inhibitors of HIV-1 protease. The planned enzyme inhibition assays were unfortunately precluded by the aqueous insolubility of the selected compounds. Three ¹³C NMR chemical shift algorithms, viz., Modgraph Neural Network, Modgraph HOSE and Chern Window, have been applied to selected compounds prepared in this study. The Modgraph Neural Network algorithm was found, in all cases, to provide the most accurate correlations with the experimentally-determined chemical shifts. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2007
- Authors: Rose, Nathan Rolf
- Date: 2007 , 2013-07-01
- Subjects: Coumarins , Protease Inhibitors , Heterocyclic compounds -- Derivatives , HIV infections -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4430 , http://hdl.handle.net/10962/d1007220 , Coumarins , Protease Inhibitors , Heterocyclic compounds -- Derivatives , HIV infections -- Treatment
- Description: This research has focused on the development of novel coumann derivatives containing peptide-like side chains as potential HIV-1 protease inhibitors. The reaction of various salicylaldehyde derivatives with tert-butyl acrylate In the presence of 1,4- diazabicyclo[2.2.2]octane (DABCO) has afforded a series of Baylis-Hillman adducts in moderate yield. Cyclisation of the adducts in the presence of HCI afforded the corresponding 3-(chloromethyl)coumarin derivatives, which have been reacted with various amine hydrochlorides in the presence of Proton Sponge® to afford a series of novel 3- (aminomethyl)coumarin derivatives, which were fully characterised by NMR and HRMS methods. Various approaches to the introduction of hydroxyl or amino groups at the C-4 position of coumarin and the 3-(chloromethyl)coumarin derivatives have been explored; these have included dihydroxylation of the coumarin double bond, and the synthesis of 4- benzylaminocoumarin derivatives as potential intermediates. The Vilsmeier-Haack and Mannich reactions have also been investigated as possible methods of introducing the desired peptide-like functionality. Computer modelling of selected structures has indicated that some of the novel 3- (aminomethyl)coumarin derivatives may exhibit activity as inhibitors of HIV-1 protease. The planned enzyme inhibition assays were unfortunately precluded by the aqueous insolubility of the selected compounds. Three ¹³C NMR chemical shift algorithms, viz., Modgraph Neural Network, Modgraph HOSE and Chern Window, have been applied to selected compounds prepared in this study. The Modgraph Neural Network algorithm was found, in all cases, to provide the most accurate correlations with the experimentally-determined chemical shifts. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2007
Synthesis of P-Methane-3,8-Diol
- Authors: Mpuhlu, Batsho
- Date: 2007
- Subjects: Insect baits and repellents
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10411 , http://hdl.handle.net/10948/570 , http://hdl.handle.net/10948/d1011717 , Insect baits and repellents
- Description: The synthesis of para-menthane-3,8-diol in a batch reactor was investigated in some detail with the view to evaluate the potential of producing said p-menthane- 3,8-diol in a continuous-flow reactor from the results obtained from the batch process. The methodology used as base for this investigation was a published procedure by Takasago of Japan. The Takasago-method produced 92.3 percent Yield for the product para-menthane-3,8-diol, and 2.7 percent Yield of the by-product, acetal. The objective for this investigation was to produce a minimum p-menthane-3,8- diol content of 97.0 percent and a maximum content of 3.0 percent for the by-product acetal. The batch production process was evaluated in detail using statistical experimental design methodologies. Three process variables, namely catalyst loading, organic/aqueous phase ratio and reaction temperature were selected for the study. The experimental method was based on the Takasago procedure, however the substrate was added as a single slug as opposed to gradual addition method and the reaction period was reduced to 30 minutes. Apart from statistical analysis, mechanistic aspects were also used to interpret the following results. Using a central composite design, three response models (one for the conversion of citronellal, p-menthane-3,8-diol and acetal formation) were determined. An analysis of the response surfaces indicated that, to increase the citronellal conversion all three variables should be increased. To increase the amount of pmenthane- 3,8-diol, the reaction temperature and acid concentration should be increased, but the Aq/org ratio should be decreased as the acid catalyst concentration is increased. To minimize the amount of acetals formed during the reaction, the Aq/org ratio should be decreased; temperature and acid concentration can be decreased or increased. The reaction mechanism suggested that p-menthane-3,8-diol may be formed along two pathways: One pathway directly forms p-menthane-3,8-diol, whilst the second pathway forms the isopulegol first, then proceeds to form product by hydrolysis. The acetal is formed as result of the reaction between unreacted citronellal and p-menthane-3,8-diol. From the design experiments it was suggested that reaction time can be reduced to 8 minutes at reaction temperatures between, 80-85 0C The product and acetal were isolated by simple vacuum evaporation of the low boiling citronellal and isopulegol. Results from recycling the catalyst phase were similar to those of the initial process. The results of this investigation has clearly shown that with a proper understanding of the effect of process variables on the performance of the batch synthesis route, the conversion of this traditionally batch (actually semi-batch) process into a continuous process is quite feasible provided that suitable equipment is available. The most important features required for such equipment would be: Intense mixing throughout the reaction zone so as to maximise the surface area between the two immiscible phases, hence the rate of mass transfer between the two phases; and the ability to run reactions above the boiling point of water. Plans for the further study of the process are already well underway and sections of static mixing tubes have been acquired to build a continuous lab scale tubular reactor that would be capable of providing the level of mixing required.
- Full Text:
- Date Issued: 2007
- Authors: Mpuhlu, Batsho
- Date: 2007
- Subjects: Insect baits and repellents
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10411 , http://hdl.handle.net/10948/570 , http://hdl.handle.net/10948/d1011717 , Insect baits and repellents
- Description: The synthesis of para-menthane-3,8-diol in a batch reactor was investigated in some detail with the view to evaluate the potential of producing said p-menthane- 3,8-diol in a continuous-flow reactor from the results obtained from the batch process. The methodology used as base for this investigation was a published procedure by Takasago of Japan. The Takasago-method produced 92.3 percent Yield for the product para-menthane-3,8-diol, and 2.7 percent Yield of the by-product, acetal. The objective for this investigation was to produce a minimum p-menthane-3,8- diol content of 97.0 percent and a maximum content of 3.0 percent for the by-product acetal. The batch production process was evaluated in detail using statistical experimental design methodologies. Three process variables, namely catalyst loading, organic/aqueous phase ratio and reaction temperature were selected for the study. The experimental method was based on the Takasago procedure, however the substrate was added as a single slug as opposed to gradual addition method and the reaction period was reduced to 30 minutes. Apart from statistical analysis, mechanistic aspects were also used to interpret the following results. Using a central composite design, three response models (one for the conversion of citronellal, p-menthane-3,8-diol and acetal formation) were determined. An analysis of the response surfaces indicated that, to increase the citronellal conversion all three variables should be increased. To increase the amount of pmenthane- 3,8-diol, the reaction temperature and acid concentration should be increased, but the Aq/org ratio should be decreased as the acid catalyst concentration is increased. To minimize the amount of acetals formed during the reaction, the Aq/org ratio should be decreased; temperature and acid concentration can be decreased or increased. The reaction mechanism suggested that p-menthane-3,8-diol may be formed along two pathways: One pathway directly forms p-menthane-3,8-diol, whilst the second pathway forms the isopulegol first, then proceeds to form product by hydrolysis. The acetal is formed as result of the reaction between unreacted citronellal and p-menthane-3,8-diol. From the design experiments it was suggested that reaction time can be reduced to 8 minutes at reaction temperatures between, 80-85 0C The product and acetal were isolated by simple vacuum evaporation of the low boiling citronellal and isopulegol. Results from recycling the catalyst phase were similar to those of the initial process. The results of this investigation has clearly shown that with a proper understanding of the effect of process variables on the performance of the batch synthesis route, the conversion of this traditionally batch (actually semi-batch) process into a continuous process is quite feasible provided that suitable equipment is available. The most important features required for such equipment would be: Intense mixing throughout the reaction zone so as to maximise the surface area between the two immiscible phases, hence the rate of mass transfer between the two phases; and the ability to run reactions above the boiling point of water. Plans for the further study of the process are already well underway and sections of static mixing tubes have been acquired to build a continuous lab scale tubular reactor that would be capable of providing the level of mixing required.
- Full Text:
- Date Issued: 2007
Synthesis of triprenylated toluquinone and toluhydroquinone metabolites from a marine-derived Penicillium fungus
- Authors: Scheepers, Brent Ashley
- Date: 2007
- Subjects: Penicillium , Antineoplastic agents , Marine fungi , Quinone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4373 , http://hdl.handle.net/10962/d1005038 , Penicillium , Antineoplastic agents , Marine fungi , Quinone
- Description: This project forms part of a collaborative effort between the marine natural products chemists at Rhodes University and the medical biochemists at the University of Cape Town’s School of Medicine. Our UCT collaborators tested the cytotoxicity of a group of toluhydroquinones and toluquinones (9-15) against the oesophageal cancer cell line WHCO1 and revealed that the triprenylated toluhydroquinone 11 and it’s oxidised analogue 12 were the most active. This thesis presents an investigation into the role of the polyprenyl side-chain in the cytotoxicity of compound 11 and it’s oxidised analogue 12 by synthesizing and testing the cytotoxicity of simplified analogues of this compound. The synthesis of the two ortho-prenylated toluhydroquinone analogues 5-methyl-2-[(2'E,6'E)-3',7' -dimethyl-2',6'-octadienyl]-1,4-benzenediol (19) and 5-methyl-2-[(2'E,6'E)-3',7',11'-trimethyl-2',6',10'-dodecatrienyl]-1,4-benzenediol (21) and their two ortho-prenylated toluquinone analogues, 5-methyl-2-[(2'E,6'E)-3',7'-dimethyl-2',6'-octadienyl]-2,5-cyclohexadiene-1,4-dione (20) and 5-methyl-2-[(2'E,6'E)-3',7',11'-trimethyl-2',6',10'-dodecatrienyl]-2,5-cyclohexadiene-1,4-dione (22) is described. Our initial attempts to couple geranyl bromide, farnesyl bromide and farnesal to the aromatic precursors m-cresol and 1,4-dimethoxy-2-methylbenzene using directed ortho-prenylation and phenoxide carbon-alkylation were unsuccessful. The four target analogues were eventually synthesized via the initial metal halogen exchange reaction between 1-bromo-2,5-dimethoxy-4-methylbenzene and geranyl bromide/farnesyl bromide using n-BuLi and TMEDA in ditheyl ether at 0 °C to yield 92 and 104 respectively in moderate yield. The demethylation of both compounds preceded smoothly using AgO giving the target analogues 20 and 22 in good yield (approx. 90 %). The reduction of quinones 20 and 22 with sodium dithionite gave 19 and 21 in quantitative yield. The synthesis reported here is the first regioselective synthesis of these compounds. The anti-oesophageal cancer activity of 19-22 and two commercially available non-prenylated analogues 17 and 18 were tested against WHCO1. The conclusion drawn from the anti-oesophageal cancer study was that the polyprenyl side-chain plays a negligable role in the cytotoxicity of compounds such as 11 and 9 against the oesophageal cancer cell line WHCO1.
- Full Text:
- Date Issued: 2007
- Authors: Scheepers, Brent Ashley
- Date: 2007
- Subjects: Penicillium , Antineoplastic agents , Marine fungi , Quinone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4373 , http://hdl.handle.net/10962/d1005038 , Penicillium , Antineoplastic agents , Marine fungi , Quinone
- Description: This project forms part of a collaborative effort between the marine natural products chemists at Rhodes University and the medical biochemists at the University of Cape Town’s School of Medicine. Our UCT collaborators tested the cytotoxicity of a group of toluhydroquinones and toluquinones (9-15) against the oesophageal cancer cell line WHCO1 and revealed that the triprenylated toluhydroquinone 11 and it’s oxidised analogue 12 were the most active. This thesis presents an investigation into the role of the polyprenyl side-chain in the cytotoxicity of compound 11 and it’s oxidised analogue 12 by synthesizing and testing the cytotoxicity of simplified analogues of this compound. The synthesis of the two ortho-prenylated toluhydroquinone analogues 5-methyl-2-[(2'E,6'E)-3',7' -dimethyl-2',6'-octadienyl]-1,4-benzenediol (19) and 5-methyl-2-[(2'E,6'E)-3',7',11'-trimethyl-2',6',10'-dodecatrienyl]-1,4-benzenediol (21) and their two ortho-prenylated toluquinone analogues, 5-methyl-2-[(2'E,6'E)-3',7'-dimethyl-2',6'-octadienyl]-2,5-cyclohexadiene-1,4-dione (20) and 5-methyl-2-[(2'E,6'E)-3',7',11'-trimethyl-2',6',10'-dodecatrienyl]-2,5-cyclohexadiene-1,4-dione (22) is described. Our initial attempts to couple geranyl bromide, farnesyl bromide and farnesal to the aromatic precursors m-cresol and 1,4-dimethoxy-2-methylbenzene using directed ortho-prenylation and phenoxide carbon-alkylation were unsuccessful. The four target analogues were eventually synthesized via the initial metal halogen exchange reaction between 1-bromo-2,5-dimethoxy-4-methylbenzene and geranyl bromide/farnesyl bromide using n-BuLi and TMEDA in ditheyl ether at 0 °C to yield 92 and 104 respectively in moderate yield. The demethylation of both compounds preceded smoothly using AgO giving the target analogues 20 and 22 in good yield (approx. 90 %). The reduction of quinones 20 and 22 with sodium dithionite gave 19 and 21 in quantitative yield. The synthesis reported here is the first regioselective synthesis of these compounds. The anti-oesophageal cancer activity of 19-22 and two commercially available non-prenylated analogues 17 and 18 were tested against WHCO1. The conclusion drawn from the anti-oesophageal cancer study was that the polyprenyl side-chain plays a negligable role in the cytotoxicity of compounds such as 11 and 9 against the oesophageal cancer cell line WHCO1.
- Full Text:
- Date Issued: 2007