Book Review : Trans : transgender life stories from South Africa, edited by Ruth Morgan, Charl Marais, and Joy R. Wellbeloved
- Authors: Morison, Tracy
- Date: 2009
- Language: English
- Type: Book review , text
- Identifier: vital:6214 , http://hdl.handle.net/10962/d1003069 , ISBN 9781920196226
- Description: ‘If you are silent about your pain, they’ll kill you and say you enjoyed it’ proclaimed author Zora Neale Hurston, writing during the US civil rights movement. Silence and pain are certainly central to the lives of many trans people. The term ‘trans’, also the book title, can be read as being inclusive of different ‘types’ of trans-identified people. The idea of transsexualism/transgenderism alone has long been unmentionable in most contexts owing to longstanding stigma and prejudice.
- Full Text:
- Date Issued: 2009
- Authors: Morison, Tracy
- Date: 2009
- Language: English
- Type: Book review , text
- Identifier: vital:6214 , http://hdl.handle.net/10962/d1003069 , ISBN 9781920196226
- Description: ‘If you are silent about your pain, they’ll kill you and say you enjoyed it’ proclaimed author Zora Neale Hurston, writing during the US civil rights movement. Silence and pain are certainly central to the lives of many trans people. The term ‘trans’, also the book title, can be read as being inclusive of different ‘types’ of trans-identified people. The idea of transsexualism/transgenderism alone has long been unmentionable in most contexts owing to longstanding stigma and prejudice.
- Full Text:
- Date Issued: 2009
Book Review: Doubly damned: the experience of HIV-positive maternity
- Authors: Morison, Tracy
- Date: 2009
- Language: English
- Type: Book review
- Identifier: vital:6213 , http://hdl.handle.net/10962/d1003068 , ISBN 978-1-86814-494-5 pbk
- Full Text:
- Date Issued: 2009
- Authors: Morison, Tracy
- Date: 2009
- Language: English
- Type: Book review
- Identifier: vital:6213 , http://hdl.handle.net/10962/d1003068 , ISBN 978-1-86814-494-5 pbk
- Full Text:
- Date Issued: 2009
Breaking down subtle and implicit racial divides in higher education institutions : an educational management perspective
- Toni, Mademoiselle Noluthando
- Authors: Toni, Mademoiselle Noluthando
- Date: 2009
- Subjects: Racism in higher education -- South Africa -- Port Elizabeth , Educational change -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9529 , http://hdl.handle.net/10948/876 , Racism in higher education -- South Africa -- Port Elizabeth , Educational change -- South Africa -- Port Elizabeth
- Description: This thesis examined the manifestations of the various forms of racism in a South African institution of higher learning, the Nelson Mandela Metropolitan University (NMMU). The study further attempted to confront racism from the perspective of finding ways in which human relations of a diversified higher education population could be improved. As the issue at hand in this study relates to racism, critical race theory (CRT) was explored in an attempt to understand different perceptions and ways of dealing with racial inequality. CRT recognizes the complexities of racism and the construction of race as a way of justifying political, economic and social inequality (Stovall, 2006:247). This understanding played a role in making sense of perceived racial discrimination which is also connected to gender, age and social class. CRT conceptual tools, such as stories and counter stories featured strongly in the data collection process. Understanding the relationships of power, race and racism, as advocated by CRT, was vital in the process of analyzing data, reporting on the findings, and the proposed recommendations. The empirical data and literature provided insight in the design of a ‘Wheel of Humanity’ which serves as a succinct portrayal of ideas that can work in nurturing acceptable, to better, human relations. The study revealed that Meta-stereotypes influenced the perceptions of racist attitudes, behaviours and practices. As much as overt forms of racism were reported as minimal, subtle and implicit forms still exist, and are aggravated by the ‘culture of power’ that is taken for granted. The success of initiatives designed for the purposes of going beyond race, and adopting a humane approach in instilling the principles of ubuntu, depends on changing attitudes and preconceived ideas.
- Full Text:
- Date Issued: 2009
- Authors: Toni, Mademoiselle Noluthando
- Date: 2009
- Subjects: Racism in higher education -- South Africa -- Port Elizabeth , Educational change -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9529 , http://hdl.handle.net/10948/876 , Racism in higher education -- South Africa -- Port Elizabeth , Educational change -- South Africa -- Port Elizabeth
- Description: This thesis examined the manifestations of the various forms of racism in a South African institution of higher learning, the Nelson Mandela Metropolitan University (NMMU). The study further attempted to confront racism from the perspective of finding ways in which human relations of a diversified higher education population could be improved. As the issue at hand in this study relates to racism, critical race theory (CRT) was explored in an attempt to understand different perceptions and ways of dealing with racial inequality. CRT recognizes the complexities of racism and the construction of race as a way of justifying political, economic and social inequality (Stovall, 2006:247). This understanding played a role in making sense of perceived racial discrimination which is also connected to gender, age and social class. CRT conceptual tools, such as stories and counter stories featured strongly in the data collection process. Understanding the relationships of power, race and racism, as advocated by CRT, was vital in the process of analyzing data, reporting on the findings, and the proposed recommendations. The empirical data and literature provided insight in the design of a ‘Wheel of Humanity’ which serves as a succinct portrayal of ideas that can work in nurturing acceptable, to better, human relations. The study revealed that Meta-stereotypes influenced the perceptions of racist attitudes, behaviours and practices. As much as overt forms of racism were reported as minimal, subtle and implicit forms still exist, and are aggravated by the ‘culture of power’ that is taken for granted. The success of initiatives designed for the purposes of going beyond race, and adopting a humane approach in instilling the principles of ubuntu, depends on changing attitudes and preconceived ideas.
- Full Text:
- Date Issued: 2009
Call centres as a vehicle to improve customer satisfaction in local government: a case study of front line workers in the Nelson Mandela Metropolitan Municipality
- Authors: Magoqwana, Babalwa Mirianda
- Date: 2009
- Subjects: Nelson Mandela Metropolitan Municipality (Eastern Cape, South Africa) Local government -- South Africa -- Eastern Cape -- Case studies Local government -- South Africa -- Eastern Cape -- Case studies Public administration -- South Africa -- Eastern Cape -- Case studies Work environment -- South Africa -- Eastern Cape -- Case studies Customer services -- South Africa -- Eastern Cape -- Case studies Customer satisfaction -- South Africa -- Eastern Cape -- Case studies Municipal services -- South Africa -- Eastern Cape -- Case studies Call center agents -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3340 , http://hdl.handle.net/10962/d1004339
- Description: This dissertation provides an account of 'Batho Pele' (People First) and 'new public management' as applied in two government call-centres in the Eastern Cape. Focusing on the workers at these call-centres, this research examines the workplace organisation of these call-centres based in the Nelson Mandela Metropolitan Municipality. The study involved interviews with managers, call-centre operators and trade unionists. The findings show how the work environment is not conducive to the goals of customer satisfaction as presented in the Batho Pele policies. The research investigates the conditions of workers as one explanatory factor for poor call-centre service. If workers are a key element in the success of the 'new public management', their work environment and conditions have to facilitate their job satisfaction and their improved customer service. The research demonstrated the evident lack of professionalism in the call-centre, customer care designed as a matter of compliance rather the need to change the culture and the persistent lack of discipline and supervision. The call centre operator's experiences include issues of surveillance, stress, emotional labour, lack of training, internal conflicts and bad 'customer service' as perceived by the citizens of the Metro.
- Full Text:
- Date Issued: 2009
- Authors: Magoqwana, Babalwa Mirianda
- Date: 2009
- Subjects: Nelson Mandela Metropolitan Municipality (Eastern Cape, South Africa) Local government -- South Africa -- Eastern Cape -- Case studies Local government -- South Africa -- Eastern Cape -- Case studies Public administration -- South Africa -- Eastern Cape -- Case studies Work environment -- South Africa -- Eastern Cape -- Case studies Customer services -- South Africa -- Eastern Cape -- Case studies Customer satisfaction -- South Africa -- Eastern Cape -- Case studies Municipal services -- South Africa -- Eastern Cape -- Case studies Call center agents -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3340 , http://hdl.handle.net/10962/d1004339
- Description: This dissertation provides an account of 'Batho Pele' (People First) and 'new public management' as applied in two government call-centres in the Eastern Cape. Focusing on the workers at these call-centres, this research examines the workplace organisation of these call-centres based in the Nelson Mandela Metropolitan Municipality. The study involved interviews with managers, call-centre operators and trade unionists. The findings show how the work environment is not conducive to the goals of customer satisfaction as presented in the Batho Pele policies. The research investigates the conditions of workers as one explanatory factor for poor call-centre service. If workers are a key element in the success of the 'new public management', their work environment and conditions have to facilitate their job satisfaction and their improved customer service. The research demonstrated the evident lack of professionalism in the call-centre, customer care designed as a matter of compliance rather the need to change the culture and the persistent lack of discipline and supervision. The call centre operator's experiences include issues of surveillance, stress, emotional labour, lack of training, internal conflicts and bad 'customer service' as perceived by the citizens of the Metro.
- Full Text:
- Date Issued: 2009
Can eyeflecks be used to sex African Black Oystercatchers Haematopus moquini in the field?
- Kohler, Sophie, Bonnevie, Bo T, Dano, Stéphanie
- Authors: Kohler, Sophie , Bonnevie, Bo T , Dano, Stéphanie
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448070 , vital:74695 , https://doi.org/10.2989/OSTRICH.2009.80.2.8.835
- Description: Morphometric differences between males and females are a common feature among oystercatcher species (Hockey 1996), although breeding partners often appear similar when observed from a distance. Combinations of different biometric parameters such as bill size and shape, body mass, wing and tarsus lengths have been used to discriminate males and females in the field in European Oystercatchers Haematopus ostralegus (Zwarts et al. 1996), American Black Oystercatchers Haematopus bachmani (Guzzetti et al. 2008) and the three oystercatcher species present in New Zealand (Baker 1973). Sexual dimorphism also occurs in the African Black Oystercatcher Haematopus moquini, an endemic species living on the coasts of Namibia and South Africa. In this species, females tend to have longer and sharper bills than males (Hockey 1981, Hockey 2005).
- Full Text:
- Date Issued: 2009
- Authors: Kohler, Sophie , Bonnevie, Bo T , Dano, Stéphanie
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448070 , vital:74695 , https://doi.org/10.2989/OSTRICH.2009.80.2.8.835
- Description: Morphometric differences between males and females are a common feature among oystercatcher species (Hockey 1996), although breeding partners often appear similar when observed from a distance. Combinations of different biometric parameters such as bill size and shape, body mass, wing and tarsus lengths have been used to discriminate males and females in the field in European Oystercatchers Haematopus ostralegus (Zwarts et al. 1996), American Black Oystercatchers Haematopus bachmani (Guzzetti et al. 2008) and the three oystercatcher species present in New Zealand (Baker 1973). Sexual dimorphism also occurs in the African Black Oystercatcher Haematopus moquini, an endemic species living on the coasts of Namibia and South Africa. In this species, females tend to have longer and sharper bills than males (Hockey 1981, Hockey 2005).
- Full Text:
- Date Issued: 2009
Cancer stem cells in breast cancer and metastasis:
- Lawson, Jessica C, Blatch, Gregory L, Edkins, Adrienne L
- Authors: Lawson, Jessica C , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165057 , vital:41205 , DOI: 10.1007/s10549-009-0524-9
- Description: The cancer stem cell theory poses that cancers develop from a subset of malignant cells that possess stem cell characteristics and has been proposed to account for the development of a variety of malignancies, including breast cancer. These cancer stem cells (CSC) possess characteristics of both stem cells and cancer cells, in that they have the properties of self-renewal, asymmetric cell division, resistance to apoptosis, independent growth, tumourigenicity and metastatic potential. A CSC origin for breast cancer can neatly explain both the heterogeneity of breast cancers and the relapse of the tumours after treatment. However, many reports on CSC in the breast are contradictory. There is variation with respect to how breast cancer stem cells should be identified, their characteristics and a possible lack of correlation between clinical outcome and breast cancer stem cell status of a tumour. These combined factors have made breast cancer stem cells a highly contentious issue. In this review, we highlight the progress in the analysis of cancer stem cells, with an emphasis on breast cancer.
- Full Text:
- Date Issued: 2009
- Authors: Lawson, Jessica C , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165057 , vital:41205 , DOI: 10.1007/s10549-009-0524-9
- Description: The cancer stem cell theory poses that cancers develop from a subset of malignant cells that possess stem cell characteristics and has been proposed to account for the development of a variety of malignancies, including breast cancer. These cancer stem cells (CSC) possess characteristics of both stem cells and cancer cells, in that they have the properties of self-renewal, asymmetric cell division, resistance to apoptosis, independent growth, tumourigenicity and metastatic potential. A CSC origin for breast cancer can neatly explain both the heterogeneity of breast cancers and the relapse of the tumours after treatment. However, many reports on CSC in the breast are contradictory. There is variation with respect to how breast cancer stem cells should be identified, their characteristics and a possible lack of correlation between clinical outcome and breast cancer stem cell status of a tumour. These combined factors have made breast cancer stem cells a highly contentious issue. In this review, we highlight the progress in the analysis of cancer stem cells, with an emphasis on breast cancer.
- Full Text:
- Date Issued: 2009
Cattle production on communal rangelands of South Africa and the potential of acacia karroo in improving Nguni beef production
- Authors: Mapiye, Cletos
- Date: 2009
- Subjects: Nguni cattle -- South Africa -- Eastern Cape , Beef cattle -- South Africa -- Eastern Cape , Beef cattle breeds -- South Africa -- Eastern Cape , Beef cattle -- Breeding -- South Africa -- Eastern Cape , Communal rangelands -- South Africa -- Eastern Cape , Grazing -- South Africa -- Eastern Cape , Range management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Animal Science)
- Identifier: vital:11161 , http://hdl.handle.net/10353/d1000989 , Nguni cattle -- South Africa -- Eastern Cape , Beef cattle -- South Africa -- Eastern Cape , Beef cattle breeds -- South Africa -- Eastern Cape , Beef cattle -- Breeding -- South Africa -- Eastern Cape , Communal rangelands -- South Africa -- Eastern Cape , Grazing -- South Africa -- Eastern Cape , Range management -- South Africa -- Eastern Cape
- Full Text:
- Date Issued: 2009
- Authors: Mapiye, Cletos
- Date: 2009
- Subjects: Nguni cattle -- South Africa -- Eastern Cape , Beef cattle -- South Africa -- Eastern Cape , Beef cattle breeds -- South Africa -- Eastern Cape , Beef cattle -- Breeding -- South Africa -- Eastern Cape , Communal rangelands -- South Africa -- Eastern Cape , Grazing -- South Africa -- Eastern Cape , Range management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Animal Science)
- Identifier: vital:11161 , http://hdl.handle.net/10353/d1000989 , Nguni cattle -- South Africa -- Eastern Cape , Beef cattle -- South Africa -- Eastern Cape , Beef cattle breeds -- South Africa -- Eastern Cape , Beef cattle -- Breeding -- South Africa -- Eastern Cape , Communal rangelands -- South Africa -- Eastern Cape , Grazing -- South Africa -- Eastern Cape , Range management -- South Africa -- Eastern Cape
- Full Text:
- Date Issued: 2009
Caught in a blamestorm: the global financial crisis
- Authors: Rumney, Reg
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454216 , vital:75328 , https://hdl.handle.net/10520/EJC139951
- Description: The outpouring of negativity towards financial journalists has been sur-prising, symbolised by TV satirist Jon Stewart's excoriation of CNBC financial commentator Jim Cramer on the Daily Show. Journalists were no more to blame for the crisis than anyone else involved in the markets. In the subsequent ''blamestorm'', however, fingers have also been pointed at economists, analysts, bankers, quants, credit rating agencies, regulators, governments, and Alan Greenspan, to name a few.
- Full Text:
- Date Issued: 2009
- Authors: Rumney, Reg
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454216 , vital:75328 , https://hdl.handle.net/10520/EJC139951
- Description: The outpouring of negativity towards financial journalists has been sur-prising, symbolised by TV satirist Jon Stewart's excoriation of CNBC financial commentator Jim Cramer on the Daily Show. Journalists were no more to blame for the crisis than anyone else involved in the markets. In the subsequent ''blamestorm'', however, fingers have also been pointed at economists, analysts, bankers, quants, credit rating agencies, regulators, governments, and Alan Greenspan, to name a few.
- Full Text:
- Date Issued: 2009
Causes and consequences of the shortage of electrical artisans at Eskom
- Authors: Toni, Thami
- Date: 2009
- Subjects: Underemployment , Manpower
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8730 , http://hdl.handle.net/10948/864 , Underemployment , Manpower
- Description: The aim of this research was to examine the causes and consequences of the shortage of electrical artisans at Eskom, using the Southern Region as a case study. Eskom used to be one of the leading public enterprises in the training of artisans to fulfil its own demand as well as to meet industry demand. This research reveals that this is no longer the case. Eskom Southern Region, a sub-division of Eskom Holdings, employs about 1700 employees. More than three quarters of these employees are employed in departments that utilise mostly electrical artisans. Natural attrition and the curtailment on the number of employees indentured and trained as electrical artisans has presented the Eskom Southern Region with a skills acquisition and retention challenge. Against this background, the study sought to discover how far Eskom Southern Region implements training and development interventions and recruitment and retention strategies in response to skill shortages. The study is based on a review of literature on skill shortages, a questionnaire opinion survey on skill shortages completed by employees at Eskom Southern Region, document study, and interviews with relevant stakeholders. The empirical study confirmed the findings of the research and skills shortages were identified for particular positions employing electrical artisans. The results show worsening skill shortages and hard-to-fill vacancies. The study proposes recommendations that encompass strategic responses, workplace-based strategies, and training-based strategies to address the shortage of electrical artisans.
- Full Text:
- Date Issued: 2009
- Authors: Toni, Thami
- Date: 2009
- Subjects: Underemployment , Manpower
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8730 , http://hdl.handle.net/10948/864 , Underemployment , Manpower
- Description: The aim of this research was to examine the causes and consequences of the shortage of electrical artisans at Eskom, using the Southern Region as a case study. Eskom used to be one of the leading public enterprises in the training of artisans to fulfil its own demand as well as to meet industry demand. This research reveals that this is no longer the case. Eskom Southern Region, a sub-division of Eskom Holdings, employs about 1700 employees. More than three quarters of these employees are employed in departments that utilise mostly electrical artisans. Natural attrition and the curtailment on the number of employees indentured and trained as electrical artisans has presented the Eskom Southern Region with a skills acquisition and retention challenge. Against this background, the study sought to discover how far Eskom Southern Region implements training and development interventions and recruitment and retention strategies in response to skill shortages. The study is based on a review of literature on skill shortages, a questionnaire opinion survey on skill shortages completed by employees at Eskom Southern Region, document study, and interviews with relevant stakeholders. The empirical study confirmed the findings of the research and skills shortages were identified for particular positions employing electrical artisans. The results show worsening skill shortages and hard-to-fill vacancies. The study proposes recommendations that encompass strategic responses, workplace-based strategies, and training-based strategies to address the shortage of electrical artisans.
- Full Text:
- Date Issued: 2009
Celebrity endorsements of branded apparel and its role in printed advertising
- Authors: Liu, Ziyu
- Date: 2009
- Subjects: Advertising -- Brand name products , Brand name products , Endorsements in advertising
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9363 , http://hdl.handle.net/10948/1178 , Advertising -- Brand name products , Brand name products , Endorsements in advertising
- Description: Purchasing is an important concept in the life of students. The decision whether to purchase branded apparel is hence a very important one. The 21st century student is less loyal and more demanding when choosing branded apparel. Marketers should understand how students evaluate celebrity endorsers when they appear in printed advertising and respond accordingly. The objective of the research is to find out how celebrity endorsed print advertisements affect Nelson Mandela Metropolitan University (NMMU) students’ purchase behaviour. The results of this study could assist marketers in improving the quality of their advertising and to more accurately meet the needs of this dynamic student market. A literature review was conducted to provide an understanding of the consumer purchasing behaviour and the role celebrity endorser played in printed advertisements. The empirical study was designed to assess the impact of the use of celebrity endorsements of printed advertisements targeted at NMMU students. The empirical findings showed that both male and female students indicated that the use of celebrity endorsers get their attention and created interest, and make advertisements more memorable. Males were more influenced than ii females. Moreover, both groups indicated that for a desired or familiar product, celebrity endorsers did not easily change their purchase decisions. It was also found that the use of pictures, colours and wording featured in the advertisements are important to students. The study proposes that marketers should continue to focus on effective marketing communications and establish whether a celebrity should be used. The correct selection of a celebrity endorser can help to create greater consumer persuasion.
- Full Text:
- Date Issued: 2009
- Authors: Liu, Ziyu
- Date: 2009
- Subjects: Advertising -- Brand name products , Brand name products , Endorsements in advertising
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9363 , http://hdl.handle.net/10948/1178 , Advertising -- Brand name products , Brand name products , Endorsements in advertising
- Description: Purchasing is an important concept in the life of students. The decision whether to purchase branded apparel is hence a very important one. The 21st century student is less loyal and more demanding when choosing branded apparel. Marketers should understand how students evaluate celebrity endorsers when they appear in printed advertising and respond accordingly. The objective of the research is to find out how celebrity endorsed print advertisements affect Nelson Mandela Metropolitan University (NMMU) students’ purchase behaviour. The results of this study could assist marketers in improving the quality of their advertising and to more accurately meet the needs of this dynamic student market. A literature review was conducted to provide an understanding of the consumer purchasing behaviour and the role celebrity endorser played in printed advertisements. The empirical study was designed to assess the impact of the use of celebrity endorsements of printed advertisements targeted at NMMU students. The empirical findings showed that both male and female students indicated that the use of celebrity endorsers get their attention and created interest, and make advertisements more memorable. Males were more influenced than ii females. Moreover, both groups indicated that for a desired or familiar product, celebrity endorsers did not easily change their purchase decisions. It was also found that the use of pictures, colours and wording featured in the advertisements are important to students. The study proposes that marketers should continue to focus on effective marketing communications and establish whether a celebrity should be used. The correct selection of a celebrity endorser can help to create greater consumer persuasion.
- Full Text:
- Date Issued: 2009
Challenges faced by female managers in schools within the Nelson Mandela Metropole
- Authors: Paulsen, Shareen Erica
- Date: 2009
- Subjects: Women school principals , Women -- Education , Feminism and education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9528 , http://hdl.handle.net/10948/897 , Women school principals , Women -- Education , Feminism and education
- Description: This study seeks to identify and examine the challenges that female principals experience. Women are slowly climbing the promotional ladder within education, yet they experience many challenges. The fact that society has the perception that women are mothers and caregivers does not make the advancement of females easy. Although the GETT report (1996) made recommendations to ensure equality in education females are still vastly under-represented in managerial positions in education. The study was conducted from a feminine perspective. It is a qualitative case study and individual interviews, a focus group interview, observation and field notes were used to collect data. A total of three females were included in the study. Participants were purposefully selected. Two of the participants are from disadvantaged schools while the third one is an ex-Model C principal. A consent form was sent to all the participants, covering all ethical issues of voluntary participation, confidentiality and anonymity. The main question was the challenges faced by female managers in education. Having spent time with each of the principals the data in the form of field notes and transcripts were analysed. It was found that the three principals experienced similar challenges. Their responses did not always reflect what the literature said regarding the challenges. All three principals felt that more formal support structures from the DoE is needed. They mentioned that the following could be implemented to ensure that they are more effective and better prepared to face these challenges: Workshops; Mentoring and Networking; Financial Assistance; and, Capacity Building.
- Full Text:
- Date Issued: 2009
- Authors: Paulsen, Shareen Erica
- Date: 2009
- Subjects: Women school principals , Women -- Education , Feminism and education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9528 , http://hdl.handle.net/10948/897 , Women school principals , Women -- Education , Feminism and education
- Description: This study seeks to identify and examine the challenges that female principals experience. Women are slowly climbing the promotional ladder within education, yet they experience many challenges. The fact that society has the perception that women are mothers and caregivers does not make the advancement of females easy. Although the GETT report (1996) made recommendations to ensure equality in education females are still vastly under-represented in managerial positions in education. The study was conducted from a feminine perspective. It is a qualitative case study and individual interviews, a focus group interview, observation and field notes were used to collect data. A total of three females were included in the study. Participants were purposefully selected. Two of the participants are from disadvantaged schools while the third one is an ex-Model C principal. A consent form was sent to all the participants, covering all ethical issues of voluntary participation, confidentiality and anonymity. The main question was the challenges faced by female managers in education. Having spent time with each of the principals the data in the form of field notes and transcripts were analysed. It was found that the three principals experienced similar challenges. Their responses did not always reflect what the literature said regarding the challenges. All three principals felt that more formal support structures from the DoE is needed. They mentioned that the following could be implemented to ensure that they are more effective and better prepared to face these challenges: Workshops; Mentoring and Networking; Financial Assistance; and, Capacity Building.
- Full Text:
- Date Issued: 2009
Challenges for South African anthropology in the 3rd Millennium
- Authors: Palmer, Robin C G
- Date: 2009
- Language: English
- Type: Text
- Identifier: vital:6111 , http://hdl.handle.net/10962/d1008105
- Description: Towards the end of one’s career, there’s a powerful inclination to look backwards instead of forwards. You become more interested in histories, biographies and obituaries; you reflect on your own life and career. It’s not inevitable, and it can be resisted. Marshall McLuhan was well into his 50s – an obscure Canadian Eng Lit academic – when he had his vision of the nature and future of the media and anticipated a ‘global village’ that the Internet has turned into a reality since his death in 1980 (McLuhan and Powers 1989) – but more on that in due course. Cui Bono? At first I gave into the tendency to look back. Initially, for this lecture, I thought to analyse my own career in South Africa in terms of who benefited most from it: South African anthropology and my students … or me. I would call the lecture ‘Cui Bono?’ But then I realised, with Latin tags on the way out, younger colleagues and students in the audience might think I was referring to a traditional Australian greeting (Coo-ee) and an Irish philanthropist pop singer (Bono). The title would be totally mystifying to many until I explained that it meant ‘to whom the good’ – in other words, who benefits? But there were other objections to this project besides the title. Even the most postmodern of reflexive anthropologists would balk at making such a self-assessment – it was not for me to judge. Anyway, I already knew the answer: My career in South Africa has not been impeded by political harassments, imprisonment or conscription. I did make some small negligible contributions to the ‘struggle’ through writing or drawing, and I did some community service, on campus or off in the same way. At a critical stage I assisted with the process that eventually produced a national staff association, now called NTESU. The only price I have paid for these distractions from serious publishing at a critical stage of my career was deservedly slow promotion. I continue to contribute to the community mainly through membership of the older of Grahamstown’s two very active Rotary clubs. It’s all I have time for, but nothing to boast about. In sum, I’ve enjoyed what my long-term colleague and Grahamstown’s Citizen of the Year (another Rotary initiative) Michael Whisson likes to call ‘sheltered employment’ – his typically ironic way of reminding us of how privileged we academics are, doing what we enjoy, in pleasant surroundings, among intelligent colleagues and the cream of our youth, with plenty of flexi-time and opportunities for subsidized travel. And now I have benefited again by being promoted to full professor without sufficiently earning my keep through subsidies on academic outputs. Whatever I might have given back through teaching and administration the net is in my favour, and I am grateful beyond words.
- Full Text:
- Date Issued: 2009
- Authors: Palmer, Robin C G
- Date: 2009
- Language: English
- Type: Text
- Identifier: vital:6111 , http://hdl.handle.net/10962/d1008105
- Description: Towards the end of one’s career, there’s a powerful inclination to look backwards instead of forwards. You become more interested in histories, biographies and obituaries; you reflect on your own life and career. It’s not inevitable, and it can be resisted. Marshall McLuhan was well into his 50s – an obscure Canadian Eng Lit academic – when he had his vision of the nature and future of the media and anticipated a ‘global village’ that the Internet has turned into a reality since his death in 1980 (McLuhan and Powers 1989) – but more on that in due course. Cui Bono? At first I gave into the tendency to look back. Initially, for this lecture, I thought to analyse my own career in South Africa in terms of who benefited most from it: South African anthropology and my students … or me. I would call the lecture ‘Cui Bono?’ But then I realised, with Latin tags on the way out, younger colleagues and students in the audience might think I was referring to a traditional Australian greeting (Coo-ee) and an Irish philanthropist pop singer (Bono). The title would be totally mystifying to many until I explained that it meant ‘to whom the good’ – in other words, who benefits? But there were other objections to this project besides the title. Even the most postmodern of reflexive anthropologists would balk at making such a self-assessment – it was not for me to judge. Anyway, I already knew the answer: My career in South Africa has not been impeded by political harassments, imprisonment or conscription. I did make some small negligible contributions to the ‘struggle’ through writing or drawing, and I did some community service, on campus or off in the same way. At a critical stage I assisted with the process that eventually produced a national staff association, now called NTESU. The only price I have paid for these distractions from serious publishing at a critical stage of my career was deservedly slow promotion. I continue to contribute to the community mainly through membership of the older of Grahamstown’s two very active Rotary clubs. It’s all I have time for, but nothing to boast about. In sum, I’ve enjoyed what my long-term colleague and Grahamstown’s Citizen of the Year (another Rotary initiative) Michael Whisson likes to call ‘sheltered employment’ – his typically ironic way of reminding us of how privileged we academics are, doing what we enjoy, in pleasant surroundings, among intelligent colleagues and the cream of our youth, with plenty of flexi-time and opportunities for subsidized travel. And now I have benefited again by being promoted to full professor without sufficiently earning my keep through subsidies on academic outputs. Whatever I might have given back through teaching and administration the net is in my favour, and I am grateful beyond words.
- Full Text:
- Date Issued: 2009
Challenging retributivist intuitions
- Authors: Hawkes, Jonathan
- Date: 2009
- Subjects: Lex talionis Punishment -- Philosophy Restorative justice
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2711 , http://hdl.handle.net/10962/d1002841
- Description: Can punishment, a practice which involves the deliberate infliction of suffering, be justified? Retributivists and consequentialists argue that punishment can be justified, whereas abolitionists argue that it cannot. Retributivists argue that punishment is justified because wrongdoers deserve it, whereas punishment is justified for consequentialists because it is beneficial for society. A popular form of abolitionism is restorative justice, which is the view that all those affected by crime (perpetrators, victims and members of society) should be reconciled. In this thesis I argue that retributivist justifications for punishment are mistaken, and argue in favour of a consequentialist view. I also argue that consequentialism can accommodate the valuable features of restorative justice while avoiding the challenges faced by it. My arguments against retributivism will turn on a thought experiment. The experiment is designed to draw out the fundamental retributivist intuition that people who cause harm deserve to suffer harm in return, yet excludes most of the principles retributivists would use to justify the intuition. I will go on to argue that, even if the retributivist considerations did apply to the experiment, they would still not justify the claim that wrongdoers deserve to be punished. Most of the retributivist considerations are, therefore, not necessary for the intuition, and none of the considerations are sufficient for it. The retributivist considerations are, I contend, rationalisations, as the claim that wrongdoers deserve to suffer is based, not on good reasons, but on an unreliable intuition. I shall argue that the consequentialist considerations, while not being necessary, are sufficient for the claim that wrongdoers should be punished, and they should be punished, I maintain, in the interests of preventing greater harm from occurring.
- Full Text:
- Date Issued: 2009
- Authors: Hawkes, Jonathan
- Date: 2009
- Subjects: Lex talionis Punishment -- Philosophy Restorative justice
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2711 , http://hdl.handle.net/10962/d1002841
- Description: Can punishment, a practice which involves the deliberate infliction of suffering, be justified? Retributivists and consequentialists argue that punishment can be justified, whereas abolitionists argue that it cannot. Retributivists argue that punishment is justified because wrongdoers deserve it, whereas punishment is justified for consequentialists because it is beneficial for society. A popular form of abolitionism is restorative justice, which is the view that all those affected by crime (perpetrators, victims and members of society) should be reconciled. In this thesis I argue that retributivist justifications for punishment are mistaken, and argue in favour of a consequentialist view. I also argue that consequentialism can accommodate the valuable features of restorative justice while avoiding the challenges faced by it. My arguments against retributivism will turn on a thought experiment. The experiment is designed to draw out the fundamental retributivist intuition that people who cause harm deserve to suffer harm in return, yet excludes most of the principles retributivists would use to justify the intuition. I will go on to argue that, even if the retributivist considerations did apply to the experiment, they would still not justify the claim that wrongdoers deserve to be punished. Most of the retributivist considerations are, therefore, not necessary for the intuition, and none of the considerations are sufficient for it. The retributivist considerations are, I contend, rationalisations, as the claim that wrongdoers deserve to suffer is based, not on good reasons, but on an unreliable intuition. I shall argue that the consequentialist considerations, while not being necessary, are sufficient for the claim that wrongdoers should be punished, and they should be punished, I maintain, in the interests of preventing greater harm from occurring.
- Full Text:
- Date Issued: 2009
Chang liver cell line as a model for Type II Diabetes in the liver and possible reversal of this condition by an indigenous medicinal plant
- Authors: Williams, Saralene Iona
- Date: 2009
- Subjects: Diabetes -- Alternative treatment , Medicinal plants , Traditional medicine , Liver -- Diseases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10339 , http://hdl.handle.net/10948/d1016179
- Description: The incidence of Type 2 Diabetes Mellittus (T2DM) is increasing world wide. In Africa the limited access to health care and the insidious course of the disease lead to more severe illness and diabetic complications. There is a need to find alternative approaches to treatment and prevention that address the problems and needs of Africa. Sutherlandia frutescens (S.frutescens) is a traditional herbal plant with known anti-diabetic properties, the precise mechanism of action of S.frutescens is not known. In order to develop new approaches for treatment and prevention of T2DM the pathophysiology of T2DM must be understood. T2DM is the final outcome of a multi-organ disease characterized by early defects in muscle, adipocytes, hepatocytes and pancreatic β-cells. In this study the role of the liver was investigated because of its central role in glucose and lipid metabolism. It is hard to differentiate between all the influences in an in vivo model, so the aim of this study was to develop an in vitro model of T2DM in Chang liver cells and to determine if S.frutescens can reverse the state of insulin resistance in this model. Different culture media conditions were screened to identify a method that can be used as the T2DM model in Chang liver cells. Serum free medium (MCBD-201) supplemented with human diabetic serum, (2.5%-10%), high insulin concentrations (0.1μM-1μM), high fructose concentrations (1-10mM). and a combination of high insulin and high fructose was used for this screening. Chang liver cells cultured in MCBD-201 medium supplemented with 1mM fructose and 0.1μM insulin showed reduced glucose uptake and increased lipid accumulation. The effect of two S.frutescens extracts, two anti-diabetic drugs, metformin and ciglitazone, and a hypolipidemic drug ciprofibrate were determined and shown to increase glucose uptake and reduce lipid accumulation. It was postulated that exposing the cells to excess nutrients in the form of high fructose would stimulate the cells to become adipogenic and accumulate lipids, which would interfere with the glucose uptake and induce insulin resistance. Gene expression of PPARγ, PPARα, and SREBP-1 transcription factors regulating lipid metabolism was determined in Chang liver cells cultured in insulin resistance inducing medium over a 48 hour time course. The expression of PPARγ, known to stimulate adipogenesis was increased after 6, 24 and 48 hours of exposure (P(H1)<0.0001). The expression of PPARα, known to stimulate β-oxidation expression, was significantly decreased after 24 hours of exposure (P(H1)<0.0001). The presence of the plant extracts in the insulin resistance inducing media protect against this increase in adipogenesis and decrease in β-oxidation after 48 hours of exposure by increasing PPARα expression and decreasing PPARγ expression. A PCR Array was performed which identified 32 more potential molecular targets of S.frutescens. Five of the 32 targets identified with the PCR Array were validated using qRT-PCR. These genes play a role in lipid and glucose metabolism and protection against oxidative stress and inflammation. In summary a cellular model of insulin resistace in hepatocytes has been established and the capacity of S.frutescens to reverse this process has been demonstrated by acting as a dual PPARγ/α agonist. New genes have been identified in the development of insulin resistance and as targets of S.frutescens.
- Full Text:
- Date Issued: 2009
- Authors: Williams, Saralene Iona
- Date: 2009
- Subjects: Diabetes -- Alternative treatment , Medicinal plants , Traditional medicine , Liver -- Diseases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10339 , http://hdl.handle.net/10948/d1016179
- Description: The incidence of Type 2 Diabetes Mellittus (T2DM) is increasing world wide. In Africa the limited access to health care and the insidious course of the disease lead to more severe illness and diabetic complications. There is a need to find alternative approaches to treatment and prevention that address the problems and needs of Africa. Sutherlandia frutescens (S.frutescens) is a traditional herbal plant with known anti-diabetic properties, the precise mechanism of action of S.frutescens is not known. In order to develop new approaches for treatment and prevention of T2DM the pathophysiology of T2DM must be understood. T2DM is the final outcome of a multi-organ disease characterized by early defects in muscle, adipocytes, hepatocytes and pancreatic β-cells. In this study the role of the liver was investigated because of its central role in glucose and lipid metabolism. It is hard to differentiate between all the influences in an in vivo model, so the aim of this study was to develop an in vitro model of T2DM in Chang liver cells and to determine if S.frutescens can reverse the state of insulin resistance in this model. Different culture media conditions were screened to identify a method that can be used as the T2DM model in Chang liver cells. Serum free medium (MCBD-201) supplemented with human diabetic serum, (2.5%-10%), high insulin concentrations (0.1μM-1μM), high fructose concentrations (1-10mM). and a combination of high insulin and high fructose was used for this screening. Chang liver cells cultured in MCBD-201 medium supplemented with 1mM fructose and 0.1μM insulin showed reduced glucose uptake and increased lipid accumulation. The effect of two S.frutescens extracts, two anti-diabetic drugs, metformin and ciglitazone, and a hypolipidemic drug ciprofibrate were determined and shown to increase glucose uptake and reduce lipid accumulation. It was postulated that exposing the cells to excess nutrients in the form of high fructose would stimulate the cells to become adipogenic and accumulate lipids, which would interfere with the glucose uptake and induce insulin resistance. Gene expression of PPARγ, PPARα, and SREBP-1 transcription factors regulating lipid metabolism was determined in Chang liver cells cultured in insulin resistance inducing medium over a 48 hour time course. The expression of PPARγ, known to stimulate adipogenesis was increased after 6, 24 and 48 hours of exposure (P(H1)<0.0001). The expression of PPARα, known to stimulate β-oxidation expression, was significantly decreased after 24 hours of exposure (P(H1)<0.0001). The presence of the plant extracts in the insulin resistance inducing media protect against this increase in adipogenesis and decrease in β-oxidation after 48 hours of exposure by increasing PPARα expression and decreasing PPARγ expression. A PCR Array was performed which identified 32 more potential molecular targets of S.frutescens. Five of the 32 targets identified with the PCR Array were validated using qRT-PCR. These genes play a role in lipid and glucose metabolism and protection against oxidative stress and inflammation. In summary a cellular model of insulin resistace in hepatocytes has been established and the capacity of S.frutescens to reverse this process has been demonstrated by acting as a dual PPARγ/α agonist. New genes have been identified in the development of insulin resistance and as targets of S.frutescens.
- Full Text:
- Date Issued: 2009
Characterisation of the cellulolytic and hemicellulolytic system of Bacillus Licheniformis SVD1 and the isolation and characterisation of a multi-enzyme complex
- Authors: Van Dyk, Jacoba Susanna
- Date: 2009
- Subjects: Lignocellulose Lignocellulose -- Biotechnology Lignocellulose -- Biodegradation Plant biotechnology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3936 , http://hdl.handle.net/10962/d1003995
- Description: The biological degradation of lignocellulose into fermentable sugars for the production of liquid transportation fuels is feasible and sustainable, but equires a variety of enzymes working in synergy as lignocellulose is a complex and recalcitrant substrate. The cellulosome is a multi-enzyme complex (MEC) with a variety of cellulolytic and hemicellulolytic enzymes that appears to facilitate an enhanced synergy and efficiency, as compared to free enzymes, for the degradation of recalcitrant substrates such as lignocellulose and plant cell walls. Most of the studies on cellulosomes have focused on a few organisms; C. thermocellum, C. cellulovorans and C. cellulolyticum, and there is only limited knowledge vailable on similar complexes in other organisms. Some MECs have been identified in aerobic bacteria such as Bacillus circulans and Paenibacillus curdlanolyticus, but the nature of these MECs have not been fully elucidated. This study investigated the cellulolytic and emi-cellulolytic system of Bacillus licheniformis SVD1 with specific reference to the presence of a MEC, which has never been reported in the literature for B. licheniformis. A MEC of approximately 2,000 kDa in size, based on size exclusion chromatography using Sepharose 4B, was purified from a culture of B. licheniformis. When investigating the presence of enzyme activity in the total crude fraction as well as the MEC of a birchwood xylan culture, B. licheniformis was found to display a variety of enzyme activities on a range of substrates, although xylanases were by far the predominant enzyme activity present in both the crude and MEC fractions. Based on zymogram analysis there were three CMCases, seven xylanases, three mannanases and two pectinases in the crude fraction, while the MEC had two CMCases, seven xylanases, two mannanases and one pectinase. The pectinases in the crude could be identified as a pectin methyl esterase and a lyase, while the methyl esterase was absent in the MEC. Seventeen protein species could be detected in the MEC but only nine of these displayed activity on the substrates tested. The possible presence of a β-xylosidase in the crude fraction was deduced from thin layer chromatography (TLC) which demonstrated the production of xylose by the crude fraction. It was furthermore established that B. licheniformis SVD1 was able to regulate levels of enzyme expression based on the substrate the organism was cultured on. It was found that complexed xylanase activity had a pH optimum of between pH 6.0 and 7.0 and a temperature optimum of 55oC. Complexed xylanase activity was found to be slightly inhibited by CaCl2 and inhibited to a greater extent by EDTA. Complexed xylanase activity was further shown to be activated in the presence of xylose and xylobiose, both compounds which are products of enzymatic degradation. Ethanol was found to inhibit complexed xylanase activity. The kinetic parameters for complexed xylanase activity were measured and the Km value was calculated as 2.84 mg/ml while the maximal velocity (Vmax) was calculated as 0.146 U (μmol/min/ml). Binding studies, transmission electron microscopy (TEM) and a bioinformatic analysis was conducted to investigate whether the MEC in B. licheniformis SVD1 was a putative cellulosome. The MEC was found to be unable to bind to Avicel, but was able to bind to insoluble birchwood xylan, indicating the absence of a CBM3a domain common to cellulosomal scaffoldin proteins. TEM micrographs revealed the presence of cell surface structures on cells of B. licheniformis SVD1 cultured on cellobiose and birchwood xylan. However, it could not be established whether these cell surface structures could be ascribed to the presence of the MECs on the cell surface. Bioinformatic analysis was conducted on the available genome sequence of a different strain of B. licheniformis, namely DSM 13 and ATCC 14580. No sequence homology was found with cohesin and dockerin sequences from various cellulosomal species, indicating that these strains most likely do not encode for a cellulosome. This study described and characterised a MEC that was a functional enzyme complex and did not appear to be a mere aggregation of proteins. It displayed a variety of hemi-cellulolytic activities and the available evidence suggests that it is not a cellulosome, but should rather be termed a xylanosome. Further investigation should be carried out to determine the structural basis of this MEC.
- Full Text:
- Date Issued: 2009
- Authors: Van Dyk, Jacoba Susanna
- Date: 2009
- Subjects: Lignocellulose Lignocellulose -- Biotechnology Lignocellulose -- Biodegradation Plant biotechnology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3936 , http://hdl.handle.net/10962/d1003995
- Description: The biological degradation of lignocellulose into fermentable sugars for the production of liquid transportation fuels is feasible and sustainable, but equires a variety of enzymes working in synergy as lignocellulose is a complex and recalcitrant substrate. The cellulosome is a multi-enzyme complex (MEC) with a variety of cellulolytic and hemicellulolytic enzymes that appears to facilitate an enhanced synergy and efficiency, as compared to free enzymes, for the degradation of recalcitrant substrates such as lignocellulose and plant cell walls. Most of the studies on cellulosomes have focused on a few organisms; C. thermocellum, C. cellulovorans and C. cellulolyticum, and there is only limited knowledge vailable on similar complexes in other organisms. Some MECs have been identified in aerobic bacteria such as Bacillus circulans and Paenibacillus curdlanolyticus, but the nature of these MECs have not been fully elucidated. This study investigated the cellulolytic and emi-cellulolytic system of Bacillus licheniformis SVD1 with specific reference to the presence of a MEC, which has never been reported in the literature for B. licheniformis. A MEC of approximately 2,000 kDa in size, based on size exclusion chromatography using Sepharose 4B, was purified from a culture of B. licheniformis. When investigating the presence of enzyme activity in the total crude fraction as well as the MEC of a birchwood xylan culture, B. licheniformis was found to display a variety of enzyme activities on a range of substrates, although xylanases were by far the predominant enzyme activity present in both the crude and MEC fractions. Based on zymogram analysis there were three CMCases, seven xylanases, three mannanases and two pectinases in the crude fraction, while the MEC had two CMCases, seven xylanases, two mannanases and one pectinase. The pectinases in the crude could be identified as a pectin methyl esterase and a lyase, while the methyl esterase was absent in the MEC. Seventeen protein species could be detected in the MEC but only nine of these displayed activity on the substrates tested. The possible presence of a β-xylosidase in the crude fraction was deduced from thin layer chromatography (TLC) which demonstrated the production of xylose by the crude fraction. It was furthermore established that B. licheniformis SVD1 was able to regulate levels of enzyme expression based on the substrate the organism was cultured on. It was found that complexed xylanase activity had a pH optimum of between pH 6.0 and 7.0 and a temperature optimum of 55oC. Complexed xylanase activity was found to be slightly inhibited by CaCl2 and inhibited to a greater extent by EDTA. Complexed xylanase activity was further shown to be activated in the presence of xylose and xylobiose, both compounds which are products of enzymatic degradation. Ethanol was found to inhibit complexed xylanase activity. The kinetic parameters for complexed xylanase activity were measured and the Km value was calculated as 2.84 mg/ml while the maximal velocity (Vmax) was calculated as 0.146 U (μmol/min/ml). Binding studies, transmission electron microscopy (TEM) and a bioinformatic analysis was conducted to investigate whether the MEC in B. licheniformis SVD1 was a putative cellulosome. The MEC was found to be unable to bind to Avicel, but was able to bind to insoluble birchwood xylan, indicating the absence of a CBM3a domain common to cellulosomal scaffoldin proteins. TEM micrographs revealed the presence of cell surface structures on cells of B. licheniformis SVD1 cultured on cellobiose and birchwood xylan. However, it could not be established whether these cell surface structures could be ascribed to the presence of the MECs on the cell surface. Bioinformatic analysis was conducted on the available genome sequence of a different strain of B. licheniformis, namely DSM 13 and ATCC 14580. No sequence homology was found with cohesin and dockerin sequences from various cellulosomal species, indicating that these strains most likely do not encode for a cellulosome. This study described and characterised a MEC that was a functional enzyme complex and did not appear to be a mere aggregation of proteins. It displayed a variety of hemi-cellulolytic activities and the available evidence suggests that it is not a cellulosome, but should rather be termed a xylanosome. Further investigation should be carried out to determine the structural basis of this MEC.
- Full Text:
- Date Issued: 2009
Characterisation of the plasmodium falciparum Hsp40 chaperones and their partnerships with Hsp70
- Authors: Botha, Melissa
- Date: 2009
- Subjects: Heat shock proteins Plasmodium falciparum Protein folding Molecular chaperones Malaria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3938 , http://hdl.handle.net/10962/d1003997
- Description: Central to this research, 40 kDa Heat shock proteins (Hsp40s) are known to partner (or cochaperone) 70 kDa Heat shock proteins (Hsp70s), facilitating the selection and transfer of protein substrate to Hsp70 and the stimulation of the protein folding ability of Hsp70. Members of the diverse Hsp70-Hsp40 protein complement of Plasmodium falciparum have been implicated in the cytoprotection of this malaria parasite, and are thought to facilitate the protein folding, assembly and translocation tasks required by the parasite to commandeer the infected human erythrocyte subsequent to invasion. In particular, the parasite has evolved an expanded and specialised 43- member suite of Hsp40 proteins, 19 of which bear an identifiable export motif for secretion into the infected erythrocyte cytoplasm where they potentially interact with human Hsp70. Although type I Hsp40 proteins are representative of typical regulators of Hsp70 activity, only two of these proteins are apparent in the parasite’s Hsp40 complement. These include a characteristic type I Hsp40 termed PfHsp40, and a larger, atypical type I Hsp40 termed Pfj1. Both Hsp40 proteins are predicted to be parasite-resident and are most likely to facilitate the co-chaperone regulation of the highly abundant and stress-inducible Hsp70 homolog, PfHsp70-I. In this work, the co-chaperone functionality of PfHsp40 and Pfj1 was elucidated using in vivo and in vitro assays. Purified recombinant PfHsp40 was shown to stimulate the ATPase activity of PfHsp70-I in in vitro single turnover and steady state ATPase assays, and co-operate with PfHsp70-I in in vitro aggregation suppression assays. In these in vitro assays, heterologous partnerships could be demonstrated between PfHsp70-I and the human Hsp40, Hsj1a, and human Hsp70 and PfHsp40, suggesting a common mode of Hsp70-Hsp40 interaction in the parasite and host organism. The functionality of the signature Hsp40 domain, the Jdomain, of Pfj1 was demonstrated by its ability to replace the equivalent domain of the A. tumefaciens Hsp40, Agt DnaJ, in interactions with the prokaryotic Hsp70, DnaK, in the thermosensitive dnaJ cbpA E. coli OD259 deletion strain. An H33Q mutation introduced into the invariant and crucial HPD tripeptide motif abrogated the functionality of the J-domain in the in vivo complementation system. These findings provide the first evidence for the conservation of the prototypical mode of J-domain based interaction of Hsp40 with Hsp70 in P. falciparum. Immunofluorescence staining revealed the localisation of PfHsp40 to the parasite cytoplasm, and Pfj1 to the parasite cytoplasm and nucleus in cultured intraerythrocytic stage P. falciparum parasites. PfHsp70-I was also shown to localise to the parasite cytoplasm and nucleus in these stages, consistent with the literature. Overall we propose that PfHsp40 and Pfj1 co-localise with and regulate the chaperone activity of PfHsp70-I in P. falciparum. This is the first study to identify and provide evidence for a functional Hsp70-Hsp40 partnership in P. falciparum, and provides a platform for future studies to elucidate the importance of these chaperone partnerships in the establishment and survival of the parasite in the intraerythrocytic-stages of development.
- Full Text:
- Date Issued: 2009
- Authors: Botha, Melissa
- Date: 2009
- Subjects: Heat shock proteins Plasmodium falciparum Protein folding Molecular chaperones Malaria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3938 , http://hdl.handle.net/10962/d1003997
- Description: Central to this research, 40 kDa Heat shock proteins (Hsp40s) are known to partner (or cochaperone) 70 kDa Heat shock proteins (Hsp70s), facilitating the selection and transfer of protein substrate to Hsp70 and the stimulation of the protein folding ability of Hsp70. Members of the diverse Hsp70-Hsp40 protein complement of Plasmodium falciparum have been implicated in the cytoprotection of this malaria parasite, and are thought to facilitate the protein folding, assembly and translocation tasks required by the parasite to commandeer the infected human erythrocyte subsequent to invasion. In particular, the parasite has evolved an expanded and specialised 43- member suite of Hsp40 proteins, 19 of which bear an identifiable export motif for secretion into the infected erythrocyte cytoplasm where they potentially interact with human Hsp70. Although type I Hsp40 proteins are representative of typical regulators of Hsp70 activity, only two of these proteins are apparent in the parasite’s Hsp40 complement. These include a characteristic type I Hsp40 termed PfHsp40, and a larger, atypical type I Hsp40 termed Pfj1. Both Hsp40 proteins are predicted to be parasite-resident and are most likely to facilitate the co-chaperone regulation of the highly abundant and stress-inducible Hsp70 homolog, PfHsp70-I. In this work, the co-chaperone functionality of PfHsp40 and Pfj1 was elucidated using in vivo and in vitro assays. Purified recombinant PfHsp40 was shown to stimulate the ATPase activity of PfHsp70-I in in vitro single turnover and steady state ATPase assays, and co-operate with PfHsp70-I in in vitro aggregation suppression assays. In these in vitro assays, heterologous partnerships could be demonstrated between PfHsp70-I and the human Hsp40, Hsj1a, and human Hsp70 and PfHsp40, suggesting a common mode of Hsp70-Hsp40 interaction in the parasite and host organism. The functionality of the signature Hsp40 domain, the Jdomain, of Pfj1 was demonstrated by its ability to replace the equivalent domain of the A. tumefaciens Hsp40, Agt DnaJ, in interactions with the prokaryotic Hsp70, DnaK, in the thermosensitive dnaJ cbpA E. coli OD259 deletion strain. An H33Q mutation introduced into the invariant and crucial HPD tripeptide motif abrogated the functionality of the J-domain in the in vivo complementation system. These findings provide the first evidence for the conservation of the prototypical mode of J-domain based interaction of Hsp40 with Hsp70 in P. falciparum. Immunofluorescence staining revealed the localisation of PfHsp40 to the parasite cytoplasm, and Pfj1 to the parasite cytoplasm and nucleus in cultured intraerythrocytic stage P. falciparum parasites. PfHsp70-I was also shown to localise to the parasite cytoplasm and nucleus in these stages, consistent with the literature. Overall we propose that PfHsp40 and Pfj1 co-localise with and regulate the chaperone activity of PfHsp70-I in P. falciparum. This is the first study to identify and provide evidence for a functional Hsp70-Hsp40 partnership in P. falciparum, and provides a platform for future studies to elucidate the importance of these chaperone partnerships in the establishment and survival of the parasite in the intraerythrocytic-stages of development.
- Full Text:
- Date Issued: 2009
Characterisation of Trypanosomal Type III and Type IV Hsp40 proteins
- Louw, Cassandra Alexandrovna
- Authors: Louw, Cassandra Alexandrovna
- Date: 2009
- Subjects: Trypanosoma Heat shock proteins African trypanosomiasis Epidemic encephalitis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3926 , http://hdl.handle.net/10962/d1003985
- Description: The heat shock protein-70 (Hsp70) family of molecular chaperones are ubiquitous highly conserved proteins that are critical for the viability of cellular homeostasis. The ATPase activity of Hsp70 proteins is critical to their function as the affinity of a given Hsp70 for non-native substrate is modulated by ATP binding and hydrolysis. When bound to ATP, Hsp70s possess a low affinity for a given substrate protein, while the hydrolysis of ATP to ADP causes a conformational change that results in a high affinity for substrate proteins. The basal ATPase activity of Hsp70s is too low to facilitate their function in vivo, and co-chaperones are essential to modulate the efficient protein folding by Hsp70. Heat shock protein-40 (Hsp40) heat shock proteins are essential for the in vivo function of Hsp70s by stimulating the ATPase activity of these proteins and facilitating transfer of substrates. The Type III class of Hsp40 proteins have not been well characterised due to their poor levels of conservation at the primary sequence level. This is due to the fact that Type III Hsp40s only contain a J-domain and a poorly conserved C-terminal region. The newly identified Type IV class of Hsp40s, contain an abrogated HPD tripeptide motif in the J-domain and have also not been extensively studied. Trypanosoma brucei (T. brucei) is a unicellular flagellated protozoan parasite. It is the causative agent of Human African Trypansomiasis (HAT) which results in thousands of deaths and devastating agricultural losses in many parts of Africa. T. brucei undergoes a complex lifecycle that is characterised by the transition from an insect vector to a mammalian host in markedly different conditions of temperature, pH, nutrient availability and respiratory requirements. It has been proposed that molecular chaperones may enhance the survival of these parasites due to their cytoprotective effect in combating cellular stress. Due to the fact that T. brucei infection is invariably fatal if left untreated, and that no novel treatment regimens have been developed recently, the identification of potential novel drug targets among proteins essential to the parasite’s survival in the host organism is an attractive aspect of T. brucei research. Because Type III Hsp40s are poorly conserved with respect to Hsp40s found in the human host, the identification of any of these proteins found to be essential to T. brucei survival in humans could potentially make attractive novel drug targets. An in depth in silico investigation into the Type III Hsp40 complement as well as partner Hsp70 proteins in T.brucei was performed. T. brucei possesses 65 Hsp40 proteins, of which 47 were classed as Type III and 6 of which were identified as being putative Type IV Hsp40s. A small but significant number (5) of Type III TbHsp40s contained tetratricopeptide (TPR) domains in addition to the J-domain. The J-domains of the Type III TbHsp40 complement were found to be conserved with respect to those of canonical Hsp40 proteins, although the mutation of certain residues that play a key role in Hsp40-Hsp70 interaction was noted. Potential partnerships of these proteins in the parasite was also investigated. The coding regions of three previously uncharacterised TbHsp40s were successfully amplified from T. brucei TREU927 genomic DNA and cloned into an expression vector. Tbj1, a Tcj1 ortholog, was selected for further study and successfully expressed and biochemically characterised. Tbj1 expressed in E. coli was found to be insoluble, but large amounts were recovered with the aid of a denaturing purification followed by refolding elution strategies, and the bulk of the protein recovered was in compact monomeric form as determined by size-exclusion chromatography fast protein liquid chromatography (SEC-FPLC). The addition of Tbj1 to a thermally aggregated substrate resulted in increased levels of aggregation, although Tbj1 was able to assist two Hsp70 proteins in the suppression of aggregation. Tbj1 proved unable to stimulate the ATPase activity of these same Hsp70s, and could not rescue temperature sensitive cells when replacing E.coli DnaJ and CbpA. It was concluded that Tbj1 does not possess independent chaperone activity, but could display Hsp40 co-chaperone properties under certain circumstances. This could allude to a specialised function in the T. brucei parasite. The lack of human orthologues to Tbj1 could result in the attractiveness of this protein as a novel drug target.
- Full Text:
- Date Issued: 2009
- Authors: Louw, Cassandra Alexandrovna
- Date: 2009
- Subjects: Trypanosoma Heat shock proteins African trypanosomiasis Epidemic encephalitis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3926 , http://hdl.handle.net/10962/d1003985
- Description: The heat shock protein-70 (Hsp70) family of molecular chaperones are ubiquitous highly conserved proteins that are critical for the viability of cellular homeostasis. The ATPase activity of Hsp70 proteins is critical to their function as the affinity of a given Hsp70 for non-native substrate is modulated by ATP binding and hydrolysis. When bound to ATP, Hsp70s possess a low affinity for a given substrate protein, while the hydrolysis of ATP to ADP causes a conformational change that results in a high affinity for substrate proteins. The basal ATPase activity of Hsp70s is too low to facilitate their function in vivo, and co-chaperones are essential to modulate the efficient protein folding by Hsp70. Heat shock protein-40 (Hsp40) heat shock proteins are essential for the in vivo function of Hsp70s by stimulating the ATPase activity of these proteins and facilitating transfer of substrates. The Type III class of Hsp40 proteins have not been well characterised due to their poor levels of conservation at the primary sequence level. This is due to the fact that Type III Hsp40s only contain a J-domain and a poorly conserved C-terminal region. The newly identified Type IV class of Hsp40s, contain an abrogated HPD tripeptide motif in the J-domain and have also not been extensively studied. Trypanosoma brucei (T. brucei) is a unicellular flagellated protozoan parasite. It is the causative agent of Human African Trypansomiasis (HAT) which results in thousands of deaths and devastating agricultural losses in many parts of Africa. T. brucei undergoes a complex lifecycle that is characterised by the transition from an insect vector to a mammalian host in markedly different conditions of temperature, pH, nutrient availability and respiratory requirements. It has been proposed that molecular chaperones may enhance the survival of these parasites due to their cytoprotective effect in combating cellular stress. Due to the fact that T. brucei infection is invariably fatal if left untreated, and that no novel treatment regimens have been developed recently, the identification of potential novel drug targets among proteins essential to the parasite’s survival in the host organism is an attractive aspect of T. brucei research. Because Type III Hsp40s are poorly conserved with respect to Hsp40s found in the human host, the identification of any of these proteins found to be essential to T. brucei survival in humans could potentially make attractive novel drug targets. An in depth in silico investigation into the Type III Hsp40 complement as well as partner Hsp70 proteins in T.brucei was performed. T. brucei possesses 65 Hsp40 proteins, of which 47 were classed as Type III and 6 of which were identified as being putative Type IV Hsp40s. A small but significant number (5) of Type III TbHsp40s contained tetratricopeptide (TPR) domains in addition to the J-domain. The J-domains of the Type III TbHsp40 complement were found to be conserved with respect to those of canonical Hsp40 proteins, although the mutation of certain residues that play a key role in Hsp40-Hsp70 interaction was noted. Potential partnerships of these proteins in the parasite was also investigated. The coding regions of three previously uncharacterised TbHsp40s were successfully amplified from T. brucei TREU927 genomic DNA and cloned into an expression vector. Tbj1, a Tcj1 ortholog, was selected for further study and successfully expressed and biochemically characterised. Tbj1 expressed in E. coli was found to be insoluble, but large amounts were recovered with the aid of a denaturing purification followed by refolding elution strategies, and the bulk of the protein recovered was in compact monomeric form as determined by size-exclusion chromatography fast protein liquid chromatography (SEC-FPLC). The addition of Tbj1 to a thermally aggregated substrate resulted in increased levels of aggregation, although Tbj1 was able to assist two Hsp70 proteins in the suppression of aggregation. Tbj1 proved unable to stimulate the ATPase activity of these same Hsp70s, and could not rescue temperature sensitive cells when replacing E.coli DnaJ and CbpA. It was concluded that Tbj1 does not possess independent chaperone activity, but could display Hsp40 co-chaperone properties under certain circumstances. This could allude to a specialised function in the T. brucei parasite. The lack of human orthologues to Tbj1 could result in the attractiveness of this protein as a novel drug target.
- Full Text:
- Date Issued: 2009
Characterization of hydrogen and helium implanted silicon carbide
- Authors: O'Connell, Jacques Herman
- Date: 2009
- Subjects: Silicon carbide , Hydrogen , Helium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10539 , http://hdl.handle.net/10948/979 , Silicon carbide , Hydrogen , Helium
- Description: This dissertation focuses on the characterization of hydrogen implanted 3C-SiC and helium implanted 6H-SiC and the interaction of silver and palladium with the SiC. The main technique used for the analysis of the implanted SiC was transmission electron microscopy (TEM), although scanning electron microscopy (SEM) and nanoindentation hardness testing were also used. Both H and He implantations were done at an ion energy of 100 keV and the total dose for both species was 1017 ions/cm2. Specimens were annealed at 1000 °C for 20 min in an inert atmosphere. The observed depth of ion damage agreed closely with that predicted by TRIM 2008. The damaged region in the He implanted specimens had a high density of small bubbles but no cracks were observed. Severe cracking was observed along the damaged region in the H implanted specimens. A second phase hexagonal (4H-SiC) was detected in two grains in the 3C-SiC and some grown in voids were also observed. The wettability of SiC by a 2:1 by volume mixture of Ag and Pd is extremely low but is significantly increased through the addition of Si to the mixture. The Si containing metal mixture was found to migrate along the grain boundaries of polycrystalline 3CSiC while sealing the point of entry. Pd attacks SiC and severe etching was observed on the surface of 6H-SiC. An epitaxially orientated Pd2Si inclusion was observed in the 6H-SiC. No effect of implantation damage on the interaction of Pd and Ag with SiC was observed. Pd etched the surface of the He implanted 6H-SiC down through the damaged region with no evidence of implantation damage left after 67 hours of annealing and thus no conclusions could be drawn. The metal mixture interacted with the non implanted surface of the H implanted 3C-SiC after dissolving the Si substrate and therefore the effect of the ion damage on the interaction could not be investigated. Nanoindentation hardness measurements showed a marked increase in hardness of He implanted 6H-SiC annealed for 20 min at 1000 °C over that of as implanted and virgin material. There was also a large decrease in hardness corresponding to the depth of the ion damage.
- Full Text:
- Date Issued: 2009
- Authors: O'Connell, Jacques Herman
- Date: 2009
- Subjects: Silicon carbide , Hydrogen , Helium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10539 , http://hdl.handle.net/10948/979 , Silicon carbide , Hydrogen , Helium
- Description: This dissertation focuses on the characterization of hydrogen implanted 3C-SiC and helium implanted 6H-SiC and the interaction of silver and palladium with the SiC. The main technique used for the analysis of the implanted SiC was transmission electron microscopy (TEM), although scanning electron microscopy (SEM) and nanoindentation hardness testing were also used. Both H and He implantations were done at an ion energy of 100 keV and the total dose for both species was 1017 ions/cm2. Specimens were annealed at 1000 °C for 20 min in an inert atmosphere. The observed depth of ion damage agreed closely with that predicted by TRIM 2008. The damaged region in the He implanted specimens had a high density of small bubbles but no cracks were observed. Severe cracking was observed along the damaged region in the H implanted specimens. A second phase hexagonal (4H-SiC) was detected in two grains in the 3C-SiC and some grown in voids were also observed. The wettability of SiC by a 2:1 by volume mixture of Ag and Pd is extremely low but is significantly increased through the addition of Si to the mixture. The Si containing metal mixture was found to migrate along the grain boundaries of polycrystalline 3CSiC while sealing the point of entry. Pd attacks SiC and severe etching was observed on the surface of 6H-SiC. An epitaxially orientated Pd2Si inclusion was observed in the 6H-SiC. No effect of implantation damage on the interaction of Pd and Ag with SiC was observed. Pd etched the surface of the He implanted 6H-SiC down through the damaged region with no evidence of implantation damage left after 67 hours of annealing and thus no conclusions could be drawn. The metal mixture interacted with the non implanted surface of the H implanted 3C-SiC after dissolving the Si substrate and therefore the effect of the ion damage on the interaction could not be investigated. Nanoindentation hardness measurements showed a marked increase in hardness of He implanted 6H-SiC annealed for 20 min at 1000 °C over that of as implanted and virgin material. There was also a large decrease in hardness corresponding to the depth of the ion damage.
- Full Text:
- Date Issued: 2009
Characterization of manganese tetraarylthiosubstituted phthalocyanines self assembled monolayers
- Matemadombo, Fungisai, Durmus, Mahmut, Togo, Chamunorwa, Limson, Janice L, Nyokong, Tebello
- Authors: Matemadombo, Fungisai , Durmus, Mahmut , Togo, Chamunorwa , Limson, Janice L , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263364 , vital:53621 , xlink:href="https://doi.org/10.1016/j.electacta.2009.04.059"
- Description: Manganese tetraarylthiosubstituted phthalocyanines (complexes 1–5) have been deposited on Au electrode surfaces through the self assembled monolayer (SAM) technique. SAM characteristics reported in this work are: ion barrier factor (∼1); interfacial capacitance (303–539 μF cm−2) and surface coverage (1.06 × 10−10–2.80 × 10−10 mol cm−2). Atomic force microscopy was employed in characterizing a SAM. SAMs of complexes 1–5 were employed to detect L-cysteine (with limit of detection ranging from 2.83 × 10−7 to 3.14 × 10−7 M at potentials of 0.68–0.75 V vs. Ag|AgCl) and nitrite (limit of detection ranging from 1.78 × 10−7 to 3.02 × 10−7 M at potentials of 0.69–0.76 V vs. Ag|AgCl).
- Full Text:
- Date Issued: 2009
- Authors: Matemadombo, Fungisai , Durmus, Mahmut , Togo, Chamunorwa , Limson, Janice L , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263364 , vital:53621 , xlink:href="https://doi.org/10.1016/j.electacta.2009.04.059"
- Description: Manganese tetraarylthiosubstituted phthalocyanines (complexes 1–5) have been deposited on Au electrode surfaces through the self assembled monolayer (SAM) technique. SAM characteristics reported in this work are: ion barrier factor (∼1); interfacial capacitance (303–539 μF cm−2) and surface coverage (1.06 × 10−10–2.80 × 10−10 mol cm−2). Atomic force microscopy was employed in characterizing a SAM. SAMs of complexes 1–5 were employed to detect L-cysteine (with limit of detection ranging from 2.83 × 10−7 to 3.14 × 10−7 M at potentials of 0.68–0.75 V vs. Ag|AgCl) and nitrite (limit of detection ranging from 1.78 × 10−7 to 3.02 × 10−7 M at potentials of 0.69–0.76 V vs. Ag|AgCl).
- Full Text:
- Date Issued: 2009
Characterization of nickel tetrahydroxy phthalocyanine complexes and the electrocatalytic oxidation of 4-chlorophenol
- Khene, Samson M, Lobb, Kevin A, Nyokong, Tebello
- Authors: Khene, Samson M , Lobb, Kevin A , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263308 , vital:53616 , xlink:href="https://doi.org/10.1016/j.ica.2009.08.019"
- Description: This work reports on the use of nickel(II) tetrahydroxy (NiPc(OH)4) and (poly-Ni(OH)Pc(OH)4) phthalocyanine complexes as films on ordinary poly graphite electrode (OPGE) for the electrochemical oxidation of 4-chlorophenol (4-CP). The NiPc(OH)4 film was electrotransformed to Ni(OH)Pc(OH)4 film in aqueous 0.1 M NaOH solution to the ‘O–Ni–O oxo’ bridge form. The result showed that the Ni(OH)Pc(OH)4 film on OPGE was more electroactive in terms of increase in current and less catalytic in terms of potential compared to the adsorbed NiPc(OH)4 on OPGE. The reactivity of the two molecules was explained by theoretical calculations. The energies of the frontier orbitals of NiPc(OH)4, Ni(OH)Pc(OH)4 and 4-chlorophenol were calculated using density functional theory (DFT) method. The inter molecular hardness (η) and donor–acceptor hardness (ηDA) of Ni(OH)Pc(OH)4, NiPc(OH)4, Ni(OH)Pc(OH)4/4-chlorophenol and NiPc(OH)4/4-chlorophenol were estimated. The Ni(OH)Pc(OH)4, showed stronger interaction with 4-chlorophenol than NiPc(OH)4. DFT method was also used to model IR and Raman spectrum of H2Pc(OH)4 and NiPc(OH)4.
- Full Text:
- Date Issued: 2009
- Authors: Khene, Samson M , Lobb, Kevin A , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263308 , vital:53616 , xlink:href="https://doi.org/10.1016/j.ica.2009.08.019"
- Description: This work reports on the use of nickel(II) tetrahydroxy (NiPc(OH)4) and (poly-Ni(OH)Pc(OH)4) phthalocyanine complexes as films on ordinary poly graphite electrode (OPGE) for the electrochemical oxidation of 4-chlorophenol (4-CP). The NiPc(OH)4 film was electrotransformed to Ni(OH)Pc(OH)4 film in aqueous 0.1 M NaOH solution to the ‘O–Ni–O oxo’ bridge form. The result showed that the Ni(OH)Pc(OH)4 film on OPGE was more electroactive in terms of increase in current and less catalytic in terms of potential compared to the adsorbed NiPc(OH)4 on OPGE. The reactivity of the two molecules was explained by theoretical calculations. The energies of the frontier orbitals of NiPc(OH)4, Ni(OH)Pc(OH)4 and 4-chlorophenol were calculated using density functional theory (DFT) method. The inter molecular hardness (η) and donor–acceptor hardness (ηDA) of Ni(OH)Pc(OH)4, NiPc(OH)4, Ni(OH)Pc(OH)4/4-chlorophenol and NiPc(OH)4/4-chlorophenol were estimated. The Ni(OH)Pc(OH)4, showed stronger interaction with 4-chlorophenol than NiPc(OH)4. DFT method was also used to model IR and Raman spectrum of H2Pc(OH)4 and NiPc(OH)4.
- Full Text:
- Date Issued: 2009