Opensource software and localisation in indigenous South African languages with Pootle
- Dalvit, Lorenzo, Terzoli, Alfredo, Wolff, F
- Authors: Dalvit, Lorenzo , Terzoli, Alfredo , Wolff, F
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428496 , vital:72515 , https://citeseerx.ist.psu.edu/document?repid=rep1andtype=pdfanddoi=912f3d0d94f0268467e1d790fd7780f14d9c4e44
- Description: The majority of the South African population is not fully proficient in Eng-lish. Besides access to the necessary infrastructure, many Africans lack epistemological access to the ICT world simply because of linguistic reasons. Limited availability of resources and lack of interest for the promotion of African languages in the ICT domain among their speakers are often blamed for this. The opensource community has been particu-larly responsive to the needs of this portion of the population, and a vari-ety of software is already available in African languages. Translate. org. za, an NGO committed to the development of opensource software in all 11 South African languages, has been particularly active with respect to this. On the one hand, they have developed a Webbased application to support collaborative translation online. On the other, they have part-nered with various institutions to organise translation efforts, mainly rely-ing on volunteers. In this paper we describe an experience showing how these two models can be used to address issues of lack of resources and support for the use of African languages in the ICT domain.
- Full Text:
- Date Issued: 2008
- Authors: Dalvit, Lorenzo , Terzoli, Alfredo , Wolff, F
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428496 , vital:72515 , https://citeseerx.ist.psu.edu/document?repid=rep1andtype=pdfanddoi=912f3d0d94f0268467e1d790fd7780f14d9c4e44
- Description: The majority of the South African population is not fully proficient in Eng-lish. Besides access to the necessary infrastructure, many Africans lack epistemological access to the ICT world simply because of linguistic reasons. Limited availability of resources and lack of interest for the promotion of African languages in the ICT domain among their speakers are often blamed for this. The opensource community has been particu-larly responsive to the needs of this portion of the population, and a vari-ety of software is already available in African languages. Translate. org. za, an NGO committed to the development of opensource software in all 11 South African languages, has been particularly active with respect to this. On the one hand, they have developed a Webbased application to support collaborative translation online. On the other, they have part-nered with various institutions to organise translation efforts, mainly rely-ing on volunteers. In this paper we describe an experience showing how these two models can be used to address issues of lack of resources and support for the use of African languages in the ICT domain.
- Full Text:
- Date Issued: 2008
Optimisation of a sampling protocol for long-term monitoring of temperate reef fishes
- Authors: Bennett, Rhett Hamilton
- Date: 2008
- Subjects: Marine parks and reserves -- South Africa , Coastal zone management -- South Africa , Fishery management -- South Africa , Reef fishes -- South Africa , Fish communities -- South Africa , Fish stock assessment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5309 , http://hdl.handle.net/10962/d1005154 , Marine parks and reserves -- South Africa , Coastal zone management -- South Africa , Fishery management -- South Africa , Reef fishes -- South Africa , Fish communities -- South Africa , Fish stock assessment
- Description: Marine Protected Areas (MPAs), the Ecosystem Approach to Fisheries management (EAF) and Integrated Coastal Management (ICM) have been identified as possible alternatives to traditional linefish management measures, which have largely failed. Monitoring and assessment of fish communities on a long-term basis is necessary, and will provide a means to evaluate the effectiveness of such management measures. Therefore, standardised protocols and optimal sampling methods for long-term monitoring (LTM) and assessment of coastal fish communities are essential. This study aimed to identify suitable methods and develop a protocol for assessment of inshore reef fish communities. A suitable location for evaluation of proposed methods was identified in the warm temperate biogeographical region of South Africa, encompassing the well-established Tsitsikamma Coastal National Park MPA and an adjacent exploited area. Chrysoblephus laticeps (roman) was identified as an indicator species for the study, as it has been well-studied and is well represented in the area. Underwater visual census (UVC) and controlled fishing were identified as suitable methods. UVC transects were found to be superior to point counts, in terms of sampling efficiency, variability, bias and required sample size. An effort of two angler hours per fishing station was shown to provide low catch variability, while at the same time a representative catch and low overall cost and required time. The methods were incorporated in a proposed sampling protocol, and evaluated. The methods were able to detect known differences between protected and exploited communities. It is recommended that LTM within protected areas, for detection of natural change, be focused on community-level indicators, while LTM in exploited areas, aimed at detection of anthropogenic change, be focused on species-level indicators. The proposed protocol with standardised methods will allow for comparisons across a network of LTM sites and provide the opportunity for a broad-scale assessment of the effects of environmental variables on reef fish stocks. The protocol developed in this study has application in other biogeographical regions in South Africa, and other parts of the world. Shift in the focus of much marine research, in South Africa and elsewhere, to LTM, highlights the relevance and timeous nature of this study.
- Full Text:
- Date Issued: 2008
- Authors: Bennett, Rhett Hamilton
- Date: 2008
- Subjects: Marine parks and reserves -- South Africa , Coastal zone management -- South Africa , Fishery management -- South Africa , Reef fishes -- South Africa , Fish communities -- South Africa , Fish stock assessment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5309 , http://hdl.handle.net/10962/d1005154 , Marine parks and reserves -- South Africa , Coastal zone management -- South Africa , Fishery management -- South Africa , Reef fishes -- South Africa , Fish communities -- South Africa , Fish stock assessment
- Description: Marine Protected Areas (MPAs), the Ecosystem Approach to Fisheries management (EAF) and Integrated Coastal Management (ICM) have been identified as possible alternatives to traditional linefish management measures, which have largely failed. Monitoring and assessment of fish communities on a long-term basis is necessary, and will provide a means to evaluate the effectiveness of such management measures. Therefore, standardised protocols and optimal sampling methods for long-term monitoring (LTM) and assessment of coastal fish communities are essential. This study aimed to identify suitable methods and develop a protocol for assessment of inshore reef fish communities. A suitable location for evaluation of proposed methods was identified in the warm temperate biogeographical region of South Africa, encompassing the well-established Tsitsikamma Coastal National Park MPA and an adjacent exploited area. Chrysoblephus laticeps (roman) was identified as an indicator species for the study, as it has been well-studied and is well represented in the area. Underwater visual census (UVC) and controlled fishing were identified as suitable methods. UVC transects were found to be superior to point counts, in terms of sampling efficiency, variability, bias and required sample size. An effort of two angler hours per fishing station was shown to provide low catch variability, while at the same time a representative catch and low overall cost and required time. The methods were incorporated in a proposed sampling protocol, and evaluated. The methods were able to detect known differences between protected and exploited communities. It is recommended that LTM within protected areas, for detection of natural change, be focused on community-level indicators, while LTM in exploited areas, aimed at detection of anthropogenic change, be focused on species-level indicators. The proposed protocol with standardised methods will allow for comparisons across a network of LTM sites and provide the opportunity for a broad-scale assessment of the effects of environmental variables on reef fish stocks. The protocol developed in this study has application in other biogeographical regions in South Africa, and other parts of the world. Shift in the focus of much marine research, in South Africa and elsewhere, to LTM, highlights the relevance and timeous nature of this study.
- Full Text:
- Date Issued: 2008
Optimisation of Bacillus thuringiensis var. israelensis (Vectobac®) applications for the blackfly control programme on the Orange River, South Africa
- Rivers-Moore, Nick A, Bangay, Shaun D, Palmer, R W
- Authors: Rivers-Moore, Nick A , Bangay, Shaun D , Palmer, R W
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:7090 , http://hdl.handle.net/10962/d1012421
- Description: The Orange River, South Africa's largest river, is a critical water resource for the country. In spite of the clear economic benefits of regulating river flows through a series of impoundments, one of the significant undesirable ecological consequences of this regulation has been the regular outbreaks of the pest blackfly species Simulium chutteri and S. damnosum s.l. (Diptera: Simuliidae). The current control programme, carried out by the South African National Department of Agriculture, uses regular applications, by helicopter, of the target-specific bacterial larvicide Bacillus thuringiensis var. israelensis. While cost-benefit analyses show significant benefits to the control programme, benefits could potentially be further increased through applying smaller volumes of larvicide in an optimised manner, which incorporates upstream residual amounts of pesticide through downstream carry. Using an optimisation technique applied in the West African Onchocerciasis Control Programme, to a 136 km stretch of the Orange River which includes 31 blackfly breeding sites, we demonstrate that 28.5% less larvicide could be used to potentially achieve the same control of blackfly. This translates into potential annual savings of between R540 000 and R1 800 000. A comparison of larvicide volumes estimated using traditional vs. optimised approaches at different discharges, illustrates that the savings on optimisation decline linearly with increasing flow volumes. Larvicide applications at the lowest discharge considered (40 m3·s-1) showed the greatest benefits from optimisations, with benefits remaining but decreasing to a theoretical 30% up to median flows of 100 m3·s-1. Given that almost 70% of flows in July are less than 100 m3·s-1, we suggest that an optimised approach is appropriate for the Orange River Blackfly Control Programme, particularly for flow volumes of less than 100 m3·s-1. We recommend that trials be undertaken over two reaches of the Orange River, one using the traditional approach, and another using the optimised approach, to test the efficacy of using optimised volumes of B.t.i.
- Full Text:
- Date Issued: 2008
- Authors: Rivers-Moore, Nick A , Bangay, Shaun D , Palmer, R W
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:7090 , http://hdl.handle.net/10962/d1012421
- Description: The Orange River, South Africa's largest river, is a critical water resource for the country. In spite of the clear economic benefits of regulating river flows through a series of impoundments, one of the significant undesirable ecological consequences of this regulation has been the regular outbreaks of the pest blackfly species Simulium chutteri and S. damnosum s.l. (Diptera: Simuliidae). The current control programme, carried out by the South African National Department of Agriculture, uses regular applications, by helicopter, of the target-specific bacterial larvicide Bacillus thuringiensis var. israelensis. While cost-benefit analyses show significant benefits to the control programme, benefits could potentially be further increased through applying smaller volumes of larvicide in an optimised manner, which incorporates upstream residual amounts of pesticide through downstream carry. Using an optimisation technique applied in the West African Onchocerciasis Control Programme, to a 136 km stretch of the Orange River which includes 31 blackfly breeding sites, we demonstrate that 28.5% less larvicide could be used to potentially achieve the same control of blackfly. This translates into potential annual savings of between R540 000 and R1 800 000. A comparison of larvicide volumes estimated using traditional vs. optimised approaches at different discharges, illustrates that the savings on optimisation decline linearly with increasing flow volumes. Larvicide applications at the lowest discharge considered (40 m3·s-1) showed the greatest benefits from optimisations, with benefits remaining but decreasing to a theoretical 30% up to median flows of 100 m3·s-1. Given that almost 70% of flows in July are less than 100 m3·s-1, we suggest that an optimised approach is appropriate for the Orange River Blackfly Control Programme, particularly for flow volumes of less than 100 m3·s-1. We recommend that trials be undertaken over two reaches of the Orange River, one using the traditional approach, and another using the optimised approach, to test the efficacy of using optimised volumes of B.t.i.
- Full Text:
- Date Issued: 2008
Oxbridge clerics and early ringing in South Africa
- Authors: Lewis, Colin A
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6186 , http://hdl.handle.net/10962/d1012384
- Description: During the early Twentieth Century, many gifted British clergy came to South Africa. They must have felt optimistic that many rings of bells would soon be installed in their adopted country. South Africa had survived the Boer Wars, the economy was reasonably healthy, new churches were being built and many others were being planned. The Union of South Africa was only a few years old and the political stability of this great part of the British Empire seemed assured. Sadly, their optimism was misplaced and in 2008 only eight rings exist in South Africa. Had it not been for the efforts of the Oxbridge trio: J.R. Vincent, G.H. Ridout and C.E.E. Bulwer, and other British immigrants, however, these rings would not exist. , Colin Lewis was Professor of Geography at Rhodes University, Grahamstown, South Africa from 1989 until his retirement at the end of 2007. In 1990, with the strong support of the incumbent Vice-Chancellor, Dr Derek Henderson, he instigated the Certificate in Change Ringing (Church Bell Ringing) in the Rhodes University Department of Music and Musicology - the first such course to be offered in Africa. Since that date he has lectured in the basic theory, and taught the practice of change ringing. He is the Ringing Master of the Cathedral of St Michael and St George, Grahamstown, South Africa.
- Full Text:
- Date Issued: 2008
- Authors: Lewis, Colin A
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6186 , http://hdl.handle.net/10962/d1012384
- Description: During the early Twentieth Century, many gifted British clergy came to South Africa. They must have felt optimistic that many rings of bells would soon be installed in their adopted country. South Africa had survived the Boer Wars, the economy was reasonably healthy, new churches were being built and many others were being planned. The Union of South Africa was only a few years old and the political stability of this great part of the British Empire seemed assured. Sadly, their optimism was misplaced and in 2008 only eight rings exist in South Africa. Had it not been for the efforts of the Oxbridge trio: J.R. Vincent, G.H. Ridout and C.E.E. Bulwer, and other British immigrants, however, these rings would not exist. , Colin Lewis was Professor of Geography at Rhodes University, Grahamstown, South Africa from 1989 until his retirement at the end of 2007. In 1990, with the strong support of the incumbent Vice-Chancellor, Dr Derek Henderson, he instigated the Certificate in Change Ringing (Church Bell Ringing) in the Rhodes University Department of Music and Musicology - the first such course to be offered in Africa. Since that date he has lectured in the basic theory, and taught the practice of change ringing. He is the Ringing Master of the Cathedral of St Michael and St George, Grahamstown, South Africa.
- Full Text:
- Date Issued: 2008
Pan-African multilateralism: transformative or disconnected?
- Authors: Bischoff, Paul, 1954-
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161452 , vital:40628 , https://doi.org/10.1080/02589340802366968
- Description: Despite a multitude of international institutions on the African continent, worldwide Africa's multilateralism has generally received little attention. Yet, with the emergence of the African Union (AU) and its institutions, questions arise about its character. Will rhetoric and state symbolism take the place of substance or will the space opened up for democracy and civil society participation allow for greater democratically informed sustainability? With this in mind, the article addresses the issue to what extent the character of African multilateralism continues to display features of disconnectedness as opposed to those of transformation, where its institutions address issues of uneven development in concert with civil society concerns.
- Full Text:
- Date Issued: 2008
- Authors: Bischoff, Paul, 1954-
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161452 , vital:40628 , https://doi.org/10.1080/02589340802366968
- Description: Despite a multitude of international institutions on the African continent, worldwide Africa's multilateralism has generally received little attention. Yet, with the emergence of the African Union (AU) and its institutions, questions arise about its character. Will rhetoric and state symbolism take the place of substance or will the space opened up for democracy and civil society participation allow for greater democratically informed sustainability? With this in mind, the article addresses the issue to what extent the character of African multilateralism continues to display features of disconnectedness as opposed to those of transformation, where its institutions address issues of uneven development in concert with civil society concerns.
- Full Text:
- Date Issued: 2008
Parasite prevalence, nutritionally-related blood metabolites and pre-slaughter stress response in Nguni, Bonsmara and Angus steers raised on veld
- Authors: Ndlovu, Thulile
- Date: 2008
- Subjects: Parasites , Nguni cattle , Bonsmara cattle , Metabolites , Slaughtering and slaughter-houses , Aberdeen -- Angus cattle
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11258 , http://hdl.handle.net/10353/73 , Parasites , Nguni cattle , Bonsmara cattle , Metabolites , Slaughtering and slaughter-houses , Aberdeen -- Angus cattle
- Description: The effects of month on body weight, body condition scores, internal parasite prevalence and on nutritionally related blood metabolites were studied in Angus, Bonsmara and Nguni steers raised on sweet veld. Pre-slaughter stress was also determined using catecholamines, cortisol, dopamine, packed cell volume and serum creatinine levels. The blood chemical constituents evaluated included glucose, cholesterol, total protein, creatinine, urea, globulin, albumin, calcium, phosphorus, magnesium, aspartate amino transferase (AST), alkaline phosphatase (ALP) and creatinine kinase (CK). The Nguni steers maintained their body condition throughout the study period whereas Angus steers had the least body condition scores. Parasite levels were high during the rainy season and low during the dry season. The predominant internal parasites were Haemonchus (39.3 percent), Trichostrongylus (37.8 percent), Cooperia pectinita (25.5 percent), Fasciola gigantica (16.3 percent) and Ostertagia ostertagi (11.2 percent). The Nguni had the least parasite infestation levels and had high PCV levels. Nguni had higher levels of cholesterol and glucose (2.86 and 4mmol/l, respectively) than the other two breeds. Nguni and Bonsmara steers had higher (P<0.05) mineral levels. There were significant breed and month differences for glucose, cholesterol, creatinine, calcium, albumin, phosphorus, albumin-globulin ratio and ALP levels. Bonsmara was more susceptible to transport and pre-slaughter stress as it had the highest (P<0.05) levels of adrenalin (10.8nmol/mol), noradrenalin (9.7nmol/mol) and dopamine (14.8nmol/mol) levels, whereas the Nguni had the least levels of adrenalin (6.5nmol/mol), noradrenalin (4.6nmol/mol) and dopamine (4nmol/mol) levels. In conclusion, Nguni steers were better adapted to the local environmental conditions
- Full Text:
- Date Issued: 2008
- Authors: Ndlovu, Thulile
- Date: 2008
- Subjects: Parasites , Nguni cattle , Bonsmara cattle , Metabolites , Slaughtering and slaughter-houses , Aberdeen -- Angus cattle
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11258 , http://hdl.handle.net/10353/73 , Parasites , Nguni cattle , Bonsmara cattle , Metabolites , Slaughtering and slaughter-houses , Aberdeen -- Angus cattle
- Description: The effects of month on body weight, body condition scores, internal parasite prevalence and on nutritionally related blood metabolites were studied in Angus, Bonsmara and Nguni steers raised on sweet veld. Pre-slaughter stress was also determined using catecholamines, cortisol, dopamine, packed cell volume and serum creatinine levels. The blood chemical constituents evaluated included glucose, cholesterol, total protein, creatinine, urea, globulin, albumin, calcium, phosphorus, magnesium, aspartate amino transferase (AST), alkaline phosphatase (ALP) and creatinine kinase (CK). The Nguni steers maintained their body condition throughout the study period whereas Angus steers had the least body condition scores. Parasite levels were high during the rainy season and low during the dry season. The predominant internal parasites were Haemonchus (39.3 percent), Trichostrongylus (37.8 percent), Cooperia pectinita (25.5 percent), Fasciola gigantica (16.3 percent) and Ostertagia ostertagi (11.2 percent). The Nguni had the least parasite infestation levels and had high PCV levels. Nguni had higher levels of cholesterol and glucose (2.86 and 4mmol/l, respectively) than the other two breeds. Nguni and Bonsmara steers had higher (P<0.05) mineral levels. There were significant breed and month differences for glucose, cholesterol, creatinine, calcium, albumin, phosphorus, albumin-globulin ratio and ALP levels. Bonsmara was more susceptible to transport and pre-slaughter stress as it had the highest (P<0.05) levels of adrenalin (10.8nmol/mol), noradrenalin (9.7nmol/mol) and dopamine (14.8nmol/mol) levels, whereas the Nguni had the least levels of adrenalin (6.5nmol/mol), noradrenalin (4.6nmol/mol) and dopamine (4nmol/mol) levels. In conclusion, Nguni steers were better adapted to the local environmental conditions
- Full Text:
- Date Issued: 2008
Participation, situated culture, and practical reason
- Lotz-Sisitka, Heila, O'Donoghue, Rob B
- Authors: Lotz-Sisitka, Heila , O'Donoghue, Rob B
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437436 , vital:73378 , ISBN 978-1-4020-6415-9 , https://link.springer.com/chapter/10.1007/978-1-4020-6416-6_7
- Description: This chapter examines the emergence of participatory education as both a central feature and a terrain of ambivalence within the develop-ing landscape of environmental education in South Africa. From its roots in nature experience activities through to more socially critical forms of environmental education, participatory imperatives in this area have yet to address sufficiently the conceptual and practical challenges inherent in pedagogies of participation. We argue that more recent de-velopments reveal similar anomalies, such that participatory education in South Africa has now become an idealised and techniqued logic of practice.
- Full Text:
- Date Issued: 2008
- Authors: Lotz-Sisitka, Heila , O'Donoghue, Rob B
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437436 , vital:73378 , ISBN 978-1-4020-6415-9 , https://link.springer.com/chapter/10.1007/978-1-4020-6416-6_7
- Description: This chapter examines the emergence of participatory education as both a central feature and a terrain of ambivalence within the develop-ing landscape of environmental education in South Africa. From its roots in nature experience activities through to more socially critical forms of environmental education, participatory imperatives in this area have yet to address sufficiently the conceptual and practical challenges inherent in pedagogies of participation. We argue that more recent de-velopments reveal similar anomalies, such that participatory education in South Africa has now become an idealised and techniqued logic of practice.
- Full Text:
- Date Issued: 2008
Patterns of risk-taking behaviour of first year university students
- Authors: Essendrup, Eugene
- Date: 2008
- Subjects: College students -- South Africa -- Social conditions , Risk-taking (Psychology)
- Language: English
- Type: Thesis , Masters , M Soc Sc (C Psy)
- Identifier: vital:11851 , http://hdl.handle.net/10353/135 , College students -- South Africa -- Social conditions , Risk-taking (Psychology)
- Description: This study investigated risk-taking behaviours among 244 first year students (Male=52 and Female=192). The risk-taking behaviours of the students were grouped into Risky and Violent Behaviour, Tobacco Use, Alcohol and Drug Use, Risky Sexual Behaviour and Unhealthy Dietary Behaviour subscales. Statistically significant correlations were found among all the risk-taking behaviour subscales other than Unhealthy Dietary Behaviours, which did not correlate with the other risky behaviours. Statistical significant sex differences were found regarding risk-taking behaviour that implicated males as higher risk-takers than females.
- Full Text:
- Date Issued: 2008
- Authors: Essendrup, Eugene
- Date: 2008
- Subjects: College students -- South Africa -- Social conditions , Risk-taking (Psychology)
- Language: English
- Type: Thesis , Masters , M Soc Sc (C Psy)
- Identifier: vital:11851 , http://hdl.handle.net/10353/135 , College students -- South Africa -- Social conditions , Risk-taking (Psychology)
- Description: This study investigated risk-taking behaviours among 244 first year students (Male=52 and Female=192). The risk-taking behaviours of the students were grouped into Risky and Violent Behaviour, Tobacco Use, Alcohol and Drug Use, Risky Sexual Behaviour and Unhealthy Dietary Behaviour subscales. Statistically significant correlations were found among all the risk-taking behaviour subscales other than Unhealthy Dietary Behaviours, which did not correlate with the other risky behaviours. Statistical significant sex differences were found regarding risk-taking behaviour that implicated males as higher risk-takers than females.
- Full Text:
- Date Issued: 2008
Perceptions of the gap between theory and practice in the preparation of English language teachers at the Lesotho College of Education
- Authors: Molete, Bakae
- Date: 2008
- Subjects: Lesotho College of Education Education -- Research -- Lesotho Teachers -- Training of -- Lesotho Student teaching -- Lesotho English language -- Study and teaching -- Lesotho Observation (Educational method) English teachers -- Training of -- Lesotho
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1936 , http://hdl.handle.net/10962/d1007682
- Description: The distinction between theory and practice can be traced back to Aristotle (384-322 B.C). Theory has been seen as the preserve of the academician who, through research, produces knowledge for the practitioner to use in his/her practice. This research sets out to investigate perceptions of the respondents with regard to the extent to which theory is applicable in practice. It does this in the context of teacher training at the Lesotho College of Education, (LCE), a teacher training college in Lesotho. In this research project; a case study of 5 students from the LCE who had been on teaching practice, their mentor teachers on teaching practice, and a college lecturer who had observed said students on teaching practice was used. Data was collected by means of focus group interviews and semi-structured interviews. Relevant documents in the form of classroom observation forms were also used. The findings from the data analysis revealed that students on teaching practice had, to a great extent, had difficulties in applying what they had learned at the college when they got to teaching practice. Difficulties were mainly experienced in the areas of classroom and time management as well as in the application of the teaching methods learned at the college. This research takes a closer look at these difficulties. It investigates their probable causes and, finally, suggests ways of responding to them.
- Full Text:
- Date Issued: 2008
- Authors: Molete, Bakae
- Date: 2008
- Subjects: Lesotho College of Education Education -- Research -- Lesotho Teachers -- Training of -- Lesotho Student teaching -- Lesotho English language -- Study and teaching -- Lesotho Observation (Educational method) English teachers -- Training of -- Lesotho
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1936 , http://hdl.handle.net/10962/d1007682
- Description: The distinction between theory and practice can be traced back to Aristotle (384-322 B.C). Theory has been seen as the preserve of the academician who, through research, produces knowledge for the practitioner to use in his/her practice. This research sets out to investigate perceptions of the respondents with regard to the extent to which theory is applicable in practice. It does this in the context of teacher training at the Lesotho College of Education, (LCE), a teacher training college in Lesotho. In this research project; a case study of 5 students from the LCE who had been on teaching practice, their mentor teachers on teaching practice, and a college lecturer who had observed said students on teaching practice was used. Data was collected by means of focus group interviews and semi-structured interviews. Relevant documents in the form of classroom observation forms were also used. The findings from the data analysis revealed that students on teaching practice had, to a great extent, had difficulties in applying what they had learned at the college when they got to teaching practice. Difficulties were mainly experienced in the areas of classroom and time management as well as in the application of the teaching methods learned at the college. This research takes a closer look at these difficulties. It investigates their probable causes and, finally, suggests ways of responding to them.
- Full Text:
- Date Issued: 2008
Perceptions on future fulfilment of visually impaired adolescent learners at the Khanyisa Special School
- Authors: Ciyana, Nontobeko Minica
- Date: 2008
- Subjects: Blind children -- Education -- South Africa -- Port Elizabeth , Children with visual disabilities -- Education -- South Africa -- Port Elizabeth , Special education -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9538 , http://hdl.handle.net/10948/683 , Blind children -- Education -- South Africa -- Port Elizabeth , Children with visual disabilities -- Education -- South Africa -- Port Elizabeth , Special education -- South Africa -- Port Elizabeth
- Description: This research focuses on the perceptions of future fulfilment of visually impaired adolescent learners at the Khanyisa Special School. The qualitative research was undertaken at the selected special school, which is situated in Nelson Mandela Bay in the western region of the Eastern Cape Province of South Africa, with ten learners, ten parents and five teachers as participants. The concluding chapter suggests ways and recommendations to assist the visually impaired adolescent learners at the Khanyisa Special School financially and academically.
- Full Text:
- Date Issued: 2008
- Authors: Ciyana, Nontobeko Minica
- Date: 2008
- Subjects: Blind children -- Education -- South Africa -- Port Elizabeth , Children with visual disabilities -- Education -- South Africa -- Port Elizabeth , Special education -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9538 , http://hdl.handle.net/10948/683 , Blind children -- Education -- South Africa -- Port Elizabeth , Children with visual disabilities -- Education -- South Africa -- Port Elizabeth , Special education -- South Africa -- Port Elizabeth
- Description: This research focuses on the perceptions of future fulfilment of visually impaired adolescent learners at the Khanyisa Special School. The qualitative research was undertaken at the selected special school, which is situated in Nelson Mandela Bay in the western region of the Eastern Cape Province of South Africa, with ten learners, ten parents and five teachers as participants. The concluding chapter suggests ways and recommendations to assist the visually impaired adolescent learners at the Khanyisa Special School financially and academically.
- Full Text:
- Date Issued: 2008
Performance of Mhande song-dance: a contextualized and comparative analysis
- Authors: Rutsate, Jerry
- Date: 2008
- Subjects: Karanga (African people) -- Music Shona (African people) -- Music Folk music -- Zimbabwe Music -- Zimbabwe Folk songs, Shona Mhande Dance music -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2655 , http://hdl.handle.net/10962/d1002321
- Description: This thesis is an investigation of the significance of Mhande song-dance in two performance contexts: the Mutoro ritual of the Karanga and the Chibuku Neshamwari Traditional Dance Competition. In addition, I undertake comparative analysis of the structure of Mhande music in relation to the structure of selected genres of Shona indigenous music. The position of Mhande in the larger context of Shona music is determined through analysis of transcriptions of the rhythmic, melodic and harmonic elements of chizambi mouth bow, karimba mbira, ngororombe panpipes, ngano story songs, game, hunting, war, and love songs. Mhande is an indigenous song-dance performed for the mutoro ceremony, the annual rain ritual of the Karanga. The Mhande repertoire consists of distinctive songs and rhythms used for communicating with the majukwa rain spirits. The rain spirits in turn communicate with God (Mwari) the provider of rain, on behalf of the Karanga. Mhande song-dance is performed exactly the same way in the annual Chibuku Neshamwari Traditional Dance Competitions as in the ritual context of the mutoro ceremony. However, in the context of the Competition, it is used for the expression of joy and as a form of cultural identity. The Competition is a forum in which Karanga songdance traditions such as Mhande, compete with other Shona song-dance traditions such as mbakumba, shangara and chinyambera. I contextualize and analyse Mhande song-dance by using the ‘Matonjeni Model’, which in terms of Karanga epistemology, is culture specific. This Model is grounded in description, interpretation and analysis; the primary methods in my research process.
- Full Text:
- Date Issued: 2008
- Authors: Rutsate, Jerry
- Date: 2008
- Subjects: Karanga (African people) -- Music Shona (African people) -- Music Folk music -- Zimbabwe Music -- Zimbabwe Folk songs, Shona Mhande Dance music -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2655 , http://hdl.handle.net/10962/d1002321
- Description: This thesis is an investigation of the significance of Mhande song-dance in two performance contexts: the Mutoro ritual of the Karanga and the Chibuku Neshamwari Traditional Dance Competition. In addition, I undertake comparative analysis of the structure of Mhande music in relation to the structure of selected genres of Shona indigenous music. The position of Mhande in the larger context of Shona music is determined through analysis of transcriptions of the rhythmic, melodic and harmonic elements of chizambi mouth bow, karimba mbira, ngororombe panpipes, ngano story songs, game, hunting, war, and love songs. Mhande is an indigenous song-dance performed for the mutoro ceremony, the annual rain ritual of the Karanga. The Mhande repertoire consists of distinctive songs and rhythms used for communicating with the majukwa rain spirits. The rain spirits in turn communicate with God (Mwari) the provider of rain, on behalf of the Karanga. Mhande song-dance is performed exactly the same way in the annual Chibuku Neshamwari Traditional Dance Competitions as in the ritual context of the mutoro ceremony. However, in the context of the Competition, it is used for the expression of joy and as a form of cultural identity. The Competition is a forum in which Karanga songdance traditions such as Mhande, compete with other Shona song-dance traditions such as mbakumba, shangara and chinyambera. I contextualize and analyse Mhande song-dance by using the ‘Matonjeni Model’, which in terms of Karanga epistemology, is culture specific. This Model is grounded in description, interpretation and analysis; the primary methods in my research process.
- Full Text:
- Date Issued: 2008
Perspectives of teachers on the problem of child sexual abuse in a squatter camp
- Authors: Bashman, Lindelwa Edna
- Date: 2008
- Subjects: Child sexual abuse -- South Africa -- Port Elizabeth , Sexually abused children -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9537 , http://hdl.handle.net/10948/684 , Child sexual abuse -- South Africa -- Port Elizabeth , Sexually abused children -- South Africa -- Port Elizabeth
- Description: Child sexual abuse is a worldwide phenomenon that takes a major toll in squatter camps in South Africa. The conditions under which the squatters live promote and aggravate the abuse. Sadly, the victims hit hardest by the abuse are the children. The negative effects caused by the abuse lead to problems in the educational tasks of these children. This study proposes that teachers can play a significant role in assisting them to overcome their problem. The aim of this study was to: • investigate the perceptions of teachers of the problem of the sexual abuse of children coming from squatter camps; • empower teachers with strategies that will help to alleviate the problem; and • formulate some recommendations on dealing with the situation in the classroom. The literature was reviewed with the aim of substantiating a compact theoretical basis for the study. Various aspects were discussed, such as • the different definitions of child sexual abuse; • short- and long-term effects of the abuse; and • contributory factors of child sexual abuse. This study followed a qualitative design, which is interpretive, naturalistic, descriptive, holistic and exploratory in nature. The participants, chosen purposefully for this study, were ten teachers, teaching children coming from a squatter camp in the Motherwell Township of Nelson Mandela Bay. Themes that emerged from the transcripts of the interviews were: • Sexual abuse has a negative effect on children and causes them to develop problems. • Teachers can play a significant role in assisting learners who are sexually abused. • There are various reasons why sexual abuse is prevalent in squatter camps. The recommendations made are based on the findings of this study and propose to empower teachers so that they will be able to make a difference in the lives of their abused learners.
- Full Text:
- Date Issued: 2008
- Authors: Bashman, Lindelwa Edna
- Date: 2008
- Subjects: Child sexual abuse -- South Africa -- Port Elizabeth , Sexually abused children -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9537 , http://hdl.handle.net/10948/684 , Child sexual abuse -- South Africa -- Port Elizabeth , Sexually abused children -- South Africa -- Port Elizabeth
- Description: Child sexual abuse is a worldwide phenomenon that takes a major toll in squatter camps in South Africa. The conditions under which the squatters live promote and aggravate the abuse. Sadly, the victims hit hardest by the abuse are the children. The negative effects caused by the abuse lead to problems in the educational tasks of these children. This study proposes that teachers can play a significant role in assisting them to overcome their problem. The aim of this study was to: • investigate the perceptions of teachers of the problem of the sexual abuse of children coming from squatter camps; • empower teachers with strategies that will help to alleviate the problem; and • formulate some recommendations on dealing with the situation in the classroom. The literature was reviewed with the aim of substantiating a compact theoretical basis for the study. Various aspects were discussed, such as • the different definitions of child sexual abuse; • short- and long-term effects of the abuse; and • contributory factors of child sexual abuse. This study followed a qualitative design, which is interpretive, naturalistic, descriptive, holistic and exploratory in nature. The participants, chosen purposefully for this study, were ten teachers, teaching children coming from a squatter camp in the Motherwell Township of Nelson Mandela Bay. Themes that emerged from the transcripts of the interviews were: • Sexual abuse has a negative effect on children and causes them to develop problems. • Teachers can play a significant role in assisting learners who are sexually abused. • There are various reasons why sexual abuse is prevalent in squatter camps. The recommendations made are based on the findings of this study and propose to empower teachers so that they will be able to make a difference in the lives of their abused learners.
- Full Text:
- Date Issued: 2008
Phosphorescence of orthopaedic–grade ultra high molecular weight polyethylene
- Authors: Chithambo, Makaiko L
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125617 , vital:35801 , https://doi.10.1002/pssc.200776802
- Description: Isothermal luminescence decay curves have been measured from orthopaedic–standard ultra high molecular weight polyethylene between 35 and 70 ˚C on the rising edge of the main glow peak at 70 ˚C. Preparatory peak-shape analysis of the temperature-resolved glow peak at 70 ˚C measured at 1 ˚C s–1 gave a geometrical factor close to 0.5 suggestive of second order kinetics for both the isothermal and thermally stimulated luminescence. The results of analysis of the phosphorescence of transformed monotonic-to-peak isothermal decay curves are also second order, as is the conclusion from thermoluminescence glow-curve de-convolution. All methods of analysis give an activation energy of about 0.7 eV.
- Full Text:
- Date Issued: 2008
- Authors: Chithambo, Makaiko L
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125617 , vital:35801 , https://doi.10.1002/pssc.200776802
- Description: Isothermal luminescence decay curves have been measured from orthopaedic–standard ultra high molecular weight polyethylene between 35 and 70 ˚C on the rising edge of the main glow peak at 70 ˚C. Preparatory peak-shape analysis of the temperature-resolved glow peak at 70 ˚C measured at 1 ˚C s–1 gave a geometrical factor close to 0.5 suggestive of second order kinetics for both the isothermal and thermally stimulated luminescence. The results of analysis of the phosphorescence of transformed monotonic-to-peak isothermal decay curves are also second order, as is the conclusion from thermoluminescence glow-curve de-convolution. All methods of analysis give an activation energy of about 0.7 eV.
- Full Text:
- Date Issued: 2008
Photocatalytic oxidation of 1-hexene using GaPc and InPc octasubstituted derivatives
- Chauke, Vongani, Nyokong, Tebello
- Authors: Chauke, Vongani , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268611 , vital:54214 , xlink:href="https://doi.org/10.1016/j.molcata.2008.04.003"
- Description: Photocatalytic oxidation of 1-hexene by GaPc (1a–1c) and InPc (2a–2c) derivatives (Pc = phthalocyanine) is hereby presented. The derivatives studied are Pc octasubstituted with phenoxy (a), 4-tert-butylphenoxy (b) or benzyloxyphenoxy (c) at the peripheral positions. The photocatalytic oxidation products for 1-hexene were 1,2-epoxyhexane and 1-hexen-3-ol. The %conversion values of 1-hexene and %selectivity of 1,2-epoxyhexane were generally higher for InPc derivatives. Even though InPc derivatives showed better photocatalytic results than GaPc derivatives, the former were less stable relative to the latter. Both type I and type II mechanism were implicated in the photocatalysis mechanism.
- Full Text:
- Date Issued: 2008
- Authors: Chauke, Vongani , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268611 , vital:54214 , xlink:href="https://doi.org/10.1016/j.molcata.2008.04.003"
- Description: Photocatalytic oxidation of 1-hexene by GaPc (1a–1c) and InPc (2a–2c) derivatives (Pc = phthalocyanine) is hereby presented. The derivatives studied are Pc octasubstituted with phenoxy (a), 4-tert-butylphenoxy (b) or benzyloxyphenoxy (c) at the peripheral positions. The photocatalytic oxidation products for 1-hexene were 1,2-epoxyhexane and 1-hexen-3-ol. The %conversion values of 1-hexene and %selectivity of 1,2-epoxyhexane were generally higher for InPc derivatives. Even though InPc derivatives showed better photocatalytic results than GaPc derivatives, the former were less stable relative to the latter. Both type I and type II mechanism were implicated in the photocatalysis mechanism.
- Full Text:
- Date Issued: 2008
Photocatalytic transformation of 4-nitrophenol in aqueous media using suspended, water-insoluble metallophthalocyanine complexes
- Marais, Eloïse A, Antunes, Edith M, Nyokong, Tebello
- Authors: Marais, Eloïse A , Antunes, Edith M , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265986 , vital:53907 , xlink:href="https://doi.org/10.1080/00958970802146056"
- Description: Unsubstituted magnesium (MgPc), zinc (ZnPc) and chloroaluminium (ClAlPc) phthalocyanine complexes and the ring substituted zinc tetranitro (ZnPc(NO2)4), zinc tetraamino (ZnPc(NH2)4), zinc hexadecafluoro (ZnPcF16) and zinc hexadecachloro (ZnPcCl16), phthalocyanine complexes are employed as photocatalysts for the heterogeneous transformation of 4-nitrophenol (4-Np) to fumaric acid and 4-nitrocatechol. ClAlPc is the best catalyst, with 89 ± 8% degradation of 4-Np after 100 min. The least effective catalysts were ZnPcCl16 and MgPc.
- Full Text:
- Date Issued: 2008
- Authors: Marais, Eloïse A , Antunes, Edith M , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265986 , vital:53907 , xlink:href="https://doi.org/10.1080/00958970802146056"
- Description: Unsubstituted magnesium (MgPc), zinc (ZnPc) and chloroaluminium (ClAlPc) phthalocyanine complexes and the ring substituted zinc tetranitro (ZnPc(NO2)4), zinc tetraamino (ZnPc(NH2)4), zinc hexadecafluoro (ZnPcF16) and zinc hexadecachloro (ZnPcCl16), phthalocyanine complexes are employed as photocatalysts for the heterogeneous transformation of 4-nitrophenol (4-Np) to fumaric acid and 4-nitrocatechol. ClAlPc is the best catalyst, with 89 ± 8% degradation of 4-Np after 100 min. The least effective catalysts were ZnPcCl16 and MgPc.
- Full Text:
- Date Issued: 2008
Photoinduced energy transfer between water-soluble CdTe quantum dots and aluminium tetrasulfonated phthalocyanine
- Idowu, Mopelola, Chen, Ji-Yao, Nyokong, Tebello
- Authors: Idowu, Mopelola , Chen, Ji-Yao , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268564 , vital:54210 , xlink:href="https://doi.org/10.1039/B707808K"
- Description: Thiol stabilized CdTe quantum dots (QDs) synthesized in aqueous phase were used as energy donors to aluminium tetrasulfonated phthalocyanine (AlTSPc) through fluorescence resonance energy transfer (FRET). Energy transfer occurred from the QDs to AlTSPc upon photoexcitation of the QDs. An enhancement in efficiency of energy transfer with the nature of the carboxylic thiol stabilizers on the QDs was observed. The results showed that for enhanced FRET to occur, the donor–acceptor distance has to be lower than the critical distance. The quenching constant K as well as the binding constant kb values were calculated suggesting strong interaction of the QDs with the AlTSPc. Study of the photophysics of AlTSPc in the presence of the QDs revealed a high triplet state yield, hence the possibility of using QDs in combination with phthalocyanines as photosensitizers in photodynamic therapy. The triplet state lifetimes of AlTSPc in the presence of the QDs were calculated and the lifetime in the presence of CdTe capped with 3-mercaptopropionic acid (MPA) was found to be the longest. MPA capped QD in a mixture with AlTSPc resulted in long triplet lifetime and high triplet yield of the latter, and high energy transfer efficiency, hence was found to be most suitable as a potential candidate for photodynamic therapy of cancer studies.
- Full Text:
- Date Issued: 2008
- Authors: Idowu, Mopelola , Chen, Ji-Yao , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268564 , vital:54210 , xlink:href="https://doi.org/10.1039/B707808K"
- Description: Thiol stabilized CdTe quantum dots (QDs) synthesized in aqueous phase were used as energy donors to aluminium tetrasulfonated phthalocyanine (AlTSPc) through fluorescence resonance energy transfer (FRET). Energy transfer occurred from the QDs to AlTSPc upon photoexcitation of the QDs. An enhancement in efficiency of energy transfer with the nature of the carboxylic thiol stabilizers on the QDs was observed. The results showed that for enhanced FRET to occur, the donor–acceptor distance has to be lower than the critical distance. The quenching constant K as well as the binding constant kb values were calculated suggesting strong interaction of the QDs with the AlTSPc. Study of the photophysics of AlTSPc in the presence of the QDs revealed a high triplet state yield, hence the possibility of using QDs in combination with phthalocyanines as photosensitizers in photodynamic therapy. The triplet state lifetimes of AlTSPc in the presence of the QDs were calculated and the lifetime in the presence of CdTe capped with 3-mercaptopropionic acid (MPA) was found to be the longest. MPA capped QD in a mixture with AlTSPc resulted in long triplet lifetime and high triplet yield of the latter, and high energy transfer efficiency, hence was found to be most suitable as a potential candidate for photodynamic therapy of cancer studies.
- Full Text:
- Date Issued: 2008
Photophysical and photochemical properties of tetrasulfonated silicon and germanium phthalocyanine in aqueous and non-aqueous media
- Idowu, Mopolela, Nyokong, Tebello
- Authors: Idowu, Mopolela , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268624 , vital:54215 , xlink:href="https://doi.org/10.1016/j.jphotochem.2008.01.004"
- Description: The photophysical and photochemical properties of tetrasulfonated silicon and germanium phthalocyanine (SiPcS4 and GePcS4) in aqueous solution (phosphate-buffered saline (PBS) solution, pH 7.4) (in the presence and absence of cremophore EL (CEL)) and in dimethylsulphoxide (DMSO) were studied. The complexes have intense absorption in the visible/near-IR region though they highly aggregate in aqueous solution with a dimerization constant of ∼2 × 104 dm3 mol−1. The fluorescence excitation spectra however have only one band suggesting that only the monomer fluoresces. Both the quantum yields of the triplet state (ΦT) and the triplet lifetimes (τT) were found to be higher in DMSO compared to in aqueous solution. Aggregation is hindered by addition of cremophore EL in aqueous solution and this induced disaggregation caused an increased ΦT and τT probably due to the reduced interaction of the phthalocyanines with the aqueous medium in the presence of CEL.
- Full Text:
- Date Issued: 2008
- Authors: Idowu, Mopolela , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268624 , vital:54215 , xlink:href="https://doi.org/10.1016/j.jphotochem.2008.01.004"
- Description: The photophysical and photochemical properties of tetrasulfonated silicon and germanium phthalocyanine (SiPcS4 and GePcS4) in aqueous solution (phosphate-buffered saline (PBS) solution, pH 7.4) (in the presence and absence of cremophore EL (CEL)) and in dimethylsulphoxide (DMSO) were studied. The complexes have intense absorption in the visible/near-IR region though they highly aggregate in aqueous solution with a dimerization constant of ∼2 × 104 dm3 mol−1. The fluorescence excitation spectra however have only one band suggesting that only the monomer fluoresces. Both the quantum yields of the triplet state (ΦT) and the triplet lifetimes (τT) were found to be higher in DMSO compared to in aqueous solution. Aggregation is hindered by addition of cremophore EL in aqueous solution and this induced disaggregation caused an increased ΦT and τT probably due to the reduced interaction of the phthalocyanines with the aqueous medium in the presence of CEL.
- Full Text:
- Date Issued: 2008
Photophysicochemical and Fluorescence quenching studies of benzyloxyphenoxy substituted zinc phthalocyanines
- Durmuş, Mahmut, Nyokong, Tebello
- Authors: Durmuş, Mahmut , Nyokong, Tebello
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6570 , http://hdl.handle.net/10962/d1004133
- Description: Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetrakis- and octakis(4-benzyloxyphenoxy)-substituted zinc phthalocyanines (1, 2 and 3). General trends are described for photodegradation, and fluorescence quantum yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulphoxide (DMSO) and toluene. The fluorescence of the complexes is quenched by benzoquinone (BQ), and fluorescence quenching properties are investigated in DMSO and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2 and 3) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications.
- Full Text:
- Date Issued: 2008
- Authors: Durmuş, Mahmut , Nyokong, Tebello
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6570 , http://hdl.handle.net/10962/d1004133
- Description: Photochemical and photophysical measurements were conducted on peripheral and non-peripheral tetrakis- and octakis(4-benzyloxyphenoxy)-substituted zinc phthalocyanines (1, 2 and 3). General trends are described for photodegradation, and fluorescence quantum yields, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulphoxide (DMSO) and toluene. The fluorescence of the complexes is quenched by benzoquinone (BQ), and fluorescence quenching properties are investigated in DMSO and toluene. The effects of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (1, 2 and 3) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications.
- Full Text:
- Date Issued: 2008
Photosensitizing properties of octacarboxy metallophthalocyanines in aqueous medium and their interaction with bovine serum albumin
- Idowu, Mopelola, Nyokong, Tebello
- Authors: Idowu, Mopelola , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/264552 , vital:53744 , xlink:href="https://doi.org/10.1016/j.jphotochem.2008.09.003"
- Description: Photosensitizing properties of aluminium, silicon, zinc and germanium octacarboxy phthalocyanines ((OH)AlOCPc, (OH)2SiOCPc, ZnOCPc and (OH)2GeOCPc) were studied in aqueous medium and in the presence of bovine serum albumin (BSA). Triplet quantum yields increased with increasing atomic number of the central metals of the metallophthalocyanine. The efficiency of singlet oxygen generation via energy transfer from the excited triplet state of the octacarboxy metallophthalocyanines (MOCPcs) to ground state oxygen increased markedly in the presence of BSA. The triplet state lifetimes of the MOCPc complexes in the presence of BSA were found to be longer than in the absence of BSA, ranging from 110 to 580 μs. These complexes bind readily to BSA. Stern–Volmer quenching constant KSV as well as the binding constant kb values were calculated. The probable mechanism of quenching of BSA fluorescence by the MOCPc complexes is by static quenching.
- Full Text:
- Date Issued: 2008
- Authors: Idowu, Mopelola , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/264552 , vital:53744 , xlink:href="https://doi.org/10.1016/j.jphotochem.2008.09.003"
- Description: Photosensitizing properties of aluminium, silicon, zinc and germanium octacarboxy phthalocyanines ((OH)AlOCPc, (OH)2SiOCPc, ZnOCPc and (OH)2GeOCPc) were studied in aqueous medium and in the presence of bovine serum albumin (BSA). Triplet quantum yields increased with increasing atomic number of the central metals of the metallophthalocyanine. The efficiency of singlet oxygen generation via energy transfer from the excited triplet state of the octacarboxy metallophthalocyanines (MOCPcs) to ground state oxygen increased markedly in the presence of BSA. The triplet state lifetimes of the MOCPc complexes in the presence of BSA were found to be longer than in the absence of BSA, ranging from 110 to 580 μs. These complexes bind readily to BSA. Stern–Volmer quenching constant KSV as well as the binding constant kb values were calculated. The probable mechanism of quenching of BSA fluorescence by the MOCPc complexes is by static quenching.
- Full Text:
- Date Issued: 2008
Photosynthetic and growth response of C₃ and C₄ subspecies of Alloteropsis semialata to nitrogen-supply
- Authors: Abraham, Trevor Ian
- Date: 2008
- Subjects: Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4182 , http://hdl.handle.net/10962/d1003750 , Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Description: The greater photosynthetic nitrogen use efficiency (PNUE) of C4 compared with C3 plants may explain the relative success of C4 grasses in nutrient poor environments. This study compared the responses in photosynthetic parameters, leaf nitrogen and biomass allocation between the C3 and C4 subspecies of Alloteropsis semialata supplied soil nitrogen at three levels. Photosynthesis was assessed by means of CO2 response curves and the leaf nitrogen content assayed. Plants were destructively harvested, leaf areas determined and the dry biomass of functional plant components was measured. Results confirmed that the higher PNUE of C4 plants allowed them to accumulate more biomass than C3 plants at the high nitrogen level, despite smaller leaf areas. The greater productivity of C4 plants enabled them to invest more in storage and sexual reproduction than in leaves when compared to the C3 plants. In contrast the C3 plants invested biomass in less efficient and more nitrogen demanding leaves and bigger root systems. PNUE and photosynthetic rates were not significantly affected by nitrogen-limitation in either subspecies and the major response was a decrease in biomass accumulation and an increase in biomass allocation to roots. This altered root to shoot ratio was accompanied by a lowered allocation to sexual reproduction in the C4 subspecies, but an unaltered allocation to leaves, while in the C3 subspecies there was a decrease in leaf allocation. In a further experiment, the C4 subspecies was supplied three levels of nitrogen provided as nitrate, or alternatively as ammonium plus nitrate, and leaves were excised to within 5 cm of the ground at the start of treatment. Prior to flowering, photosynthesis was assessed by means of CO2 response curves and the plants were destructively harvested. Leaf areas and the dry biomass of functional plant components were determined, and at levels of nitrogen supply higher than those found in savanna soils the rate of photosynthesis was increased. Leaf re-growth was reduced by severe nitrogen limitation and co-provision of nitrate and ammonium had no significant effect other than increased tillering. Both subspecies of Alloteropsis semialata are adapted to nutrient poor environments and maintain photosynthetic rates by reducing leaf area. The C4 subspecies is likely to show greater resilience in disturbance-prone environments by exploiting its higher PNUE to allocate greater resources to storage and sexual reproduction, while the C3 subspecies is usually found in environments with closed canopies which favour vegetative growth, and allocate greater resources to leaves and roots.
- Full Text:
- Date Issued: 2008
- Authors: Abraham, Trevor Ian
- Date: 2008
- Subjects: Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4182 , http://hdl.handle.net/10962/d1003750 , Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Description: The greater photosynthetic nitrogen use efficiency (PNUE) of C4 compared with C3 plants may explain the relative success of C4 grasses in nutrient poor environments. This study compared the responses in photosynthetic parameters, leaf nitrogen and biomass allocation between the C3 and C4 subspecies of Alloteropsis semialata supplied soil nitrogen at three levels. Photosynthesis was assessed by means of CO2 response curves and the leaf nitrogen content assayed. Plants were destructively harvested, leaf areas determined and the dry biomass of functional plant components was measured. Results confirmed that the higher PNUE of C4 plants allowed them to accumulate more biomass than C3 plants at the high nitrogen level, despite smaller leaf areas. The greater productivity of C4 plants enabled them to invest more in storage and sexual reproduction than in leaves when compared to the C3 plants. In contrast the C3 plants invested biomass in less efficient and more nitrogen demanding leaves and bigger root systems. PNUE and photosynthetic rates were not significantly affected by nitrogen-limitation in either subspecies and the major response was a decrease in biomass accumulation and an increase in biomass allocation to roots. This altered root to shoot ratio was accompanied by a lowered allocation to sexual reproduction in the C4 subspecies, but an unaltered allocation to leaves, while in the C3 subspecies there was a decrease in leaf allocation. In a further experiment, the C4 subspecies was supplied three levels of nitrogen provided as nitrate, or alternatively as ammonium plus nitrate, and leaves were excised to within 5 cm of the ground at the start of treatment. Prior to flowering, photosynthesis was assessed by means of CO2 response curves and the plants were destructively harvested. Leaf areas and the dry biomass of functional plant components were determined, and at levels of nitrogen supply higher than those found in savanna soils the rate of photosynthesis was increased. Leaf re-growth was reduced by severe nitrogen limitation and co-provision of nitrate and ammonium had no significant effect other than increased tillering. Both subspecies of Alloteropsis semialata are adapted to nutrient poor environments and maintain photosynthetic rates by reducing leaf area. The C4 subspecies is likely to show greater resilience in disturbance-prone environments by exploiting its higher PNUE to allocate greater resources to storage and sexual reproduction, while the C3 subspecies is usually found in environments with closed canopies which favour vegetative growth, and allocate greater resources to leaves and roots.
- Full Text:
- Date Issued: 2008