Vergelyking van Tilapia (Oreochromis Mossambicus)en Koi (Ciprinus Carpio) in verskillende produksiestelsels
- Authors: Van der Merwe, Johan Philip
- Date: 2002
- Subjects: Fish culture
- Language: Afrikaans
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10967 , http://hdl.handle.net/10948/114 , Fish culture
- Description: Die studie was uitgevoer om te bepaal of warmwaterspesies soos tilapia (Oreochromis mossambicus) en koi (Ciprinus carpio) gebruik kan word as deel van 'n roterende akwakultuur produksie sisteem in die Wes-Kaap. Drie produksiestelsels (drywende hokstelsel; gronddamme en hersirkuleringseenheid) was ge-evalueer vir beide tilapia en koi produksie. Twee verskillende diëte (tilapia, 32% proteien, 'n lae waarde dieet en koi, 32% proteien, 'n hoë waarde dieet) was ook ge-evalueer vir die effek op koi produksie. Tilapia- en koi vingerlinge was teen dieselfde lading (250/hok) in elke produksiestelsel geplaas. By die begin van die proewe het die tilapia vingerlinge 'n gemiddelde gewig van 60-80g en die koi vingerlinge 'n gemiddelde lengte van 30-40 mm gehad. Die visse is twee keer per dag gevoer en data is op 'n maandelikse basis oor 'n periode van 84 dae versamel. Produksie data vir die tilapia versamel was: 1) die gemiddelde daaglikse toename, 2) die totale voer verbruik, 3) water temperature en 4) mortaliteite is daagliks aangeteken. Die produksie data versamel vir koi wat twee verskillende diëte ontvang het in drie verskillende produksiestelsels was: 1) die gemiddelde daaglikse toename in lengte, 2) die totale voer verbruik, 3) water temperature en 4) mortaliteite is daagliks aangeteken. Die resultate van die tilapia studie het aangedui dat tilapia in die hersirkuleeringseenheid het deurgaans 'n swaarder gewig gehad (p<0.05) as die van die drywende hokstelsel en gronddam stelsel. Terwyl die gronddam stelsel weer 'n swaarder gewig gehad het as die drywende hokstelsel behalwe vir April (171,67 / 39,49 vs 159,33 / 22,15). Nieteenstaande die verskil in begin gewig en eind gewig in die guns van die tilapia in die hersirkuleringseenheid teenoor die ander twee stelsels het die GDT tussen die drywende hokstelsel en die hersirkuleringseenheid nie noemenswaardig verskil nie (1,20 / 0,15 vs 1,40 / 0,24). Die tilapia in die gronddamme het egter swakker (p<0,05) gewigstoename van 0,72 / 0,32 g gehad teenoor die tilapia in die drywende hokstesel 1,40 / 0,24 g en 1,20 / 0,15 g van die tilapia in die hersirkuleringseenheid. Tilapia in die gronddamme het dus ongeveer 45% swakker gemiddelde gewigstoename getoon as die van die drywende hokstelsel en hersirkuleringseenheid. Die produksiestelsel het 'n hoogs betekenisvolle invloed (p<0,001) op die groeipotensiaal van tilapia gehad in hierdie studie. Die gemiddelde totale hoeveelheid voer verbruik was nie statisties verskillend tussen die drywende hokstelsel en gronddam stelsel nie (29,83 / 2,66 vs 30,83 / 5,42), maar wel (p<0,05) vir die hersirkuleringseenheid (29,94 / 0,88). Die VOV het nie verskil tussen die drywende hokstelsel en hersirkuleringeenheid, maar daar was wel 'n verskil (p<0,05) tussen hierdie twee stelsels en die van die gronddamme. Die totale gemiddelde mortaliteite van tilapia was die hoogste (p<0,05) vir die drywende hokstelsel in vergelyking met die gronddamme en hersirkuleringseenheid. Die drywende hokstelsel het 14,67 / 14,61% meer mortaliteite gehad as die gronddamme en hersirkuleringeenheid. Die koi studie se resultate dui aan dat die tipe stelsel het 'n hoogs betekenisvolle (p<0,001) invloed gehad op die gemiddelde toename in lengte van die koi vis vir die somerseisoen. Die tipe dieet het geen invloed op die toename in lengte van koi vis vir al drie die stelsels ge-evalueer, maar die interaksie tussen dieet en die tipe stelsel was wel betekenisvol (p<0.05). Die interaksie tussen die tipe dieet en die tipe stelsel was die hoogste vir die groddamme 136,41 / 32,46 mm en 136,25 / 33,08 mm vir beide tilapia en die koi diëte gevoer. Die gemiddelde totale voer wat deur koi visse in die drie stelsels verbruik is, het wel statisties van mekaar verskil (p<0,05). Koi visse in die gronddam stelsel het meer voer verbruik vir beide die tilapia- en koi dieet (31,03 / 2,01 en 29,67 / 3,57) in vergelyking met die (26,35 / 2,44 ; 26,98 / 0,49 en 5,50 # 0,52 en 6,13 / 0,22) vir die drywende hokke en hersirkuleringseenheid stelsels onderskiedelik. Die % mortaliteite was betekenisvol (p<0,05) vir die verskillende stelsels. Koi visse in die hersirkuleringseenheid het die hoogste mortaliteite gehad vir beide die tilapia en die koi diëte (65,50 / 18,07% en 79,50 / 38,27%) terwyl koi visse in die gronddamme die laagste mortaliteite ondervind het (1,20 / 1,20% en 2,33 / 4,89%) vir beide die tilapia en koi diëte. Die koi in die gronddam stelsel het die beste resultate gelewer en dit is ook moontlik om koi 'n lae waarde dieet te voer sonder nadelige effekte op produksie.
- Full Text:
- Date Issued: 2002
- Authors: Van der Merwe, Johan Philip
- Date: 2002
- Subjects: Fish culture
- Language: Afrikaans
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10967 , http://hdl.handle.net/10948/114 , Fish culture
- Description: Die studie was uitgevoer om te bepaal of warmwaterspesies soos tilapia (Oreochromis mossambicus) en koi (Ciprinus carpio) gebruik kan word as deel van 'n roterende akwakultuur produksie sisteem in die Wes-Kaap. Drie produksiestelsels (drywende hokstelsel; gronddamme en hersirkuleringseenheid) was ge-evalueer vir beide tilapia en koi produksie. Twee verskillende diëte (tilapia, 32% proteien, 'n lae waarde dieet en koi, 32% proteien, 'n hoë waarde dieet) was ook ge-evalueer vir die effek op koi produksie. Tilapia- en koi vingerlinge was teen dieselfde lading (250/hok) in elke produksiestelsel geplaas. By die begin van die proewe het die tilapia vingerlinge 'n gemiddelde gewig van 60-80g en die koi vingerlinge 'n gemiddelde lengte van 30-40 mm gehad. Die visse is twee keer per dag gevoer en data is op 'n maandelikse basis oor 'n periode van 84 dae versamel. Produksie data vir die tilapia versamel was: 1) die gemiddelde daaglikse toename, 2) die totale voer verbruik, 3) water temperature en 4) mortaliteite is daagliks aangeteken. Die produksie data versamel vir koi wat twee verskillende diëte ontvang het in drie verskillende produksiestelsels was: 1) die gemiddelde daaglikse toename in lengte, 2) die totale voer verbruik, 3) water temperature en 4) mortaliteite is daagliks aangeteken. Die resultate van die tilapia studie het aangedui dat tilapia in die hersirkuleeringseenheid het deurgaans 'n swaarder gewig gehad (p<0.05) as die van die drywende hokstelsel en gronddam stelsel. Terwyl die gronddam stelsel weer 'n swaarder gewig gehad het as die drywende hokstelsel behalwe vir April (171,67 / 39,49 vs 159,33 / 22,15). Nieteenstaande die verskil in begin gewig en eind gewig in die guns van die tilapia in die hersirkuleringseenheid teenoor die ander twee stelsels het die GDT tussen die drywende hokstelsel en die hersirkuleringseenheid nie noemenswaardig verskil nie (1,20 / 0,15 vs 1,40 / 0,24). Die tilapia in die gronddamme het egter swakker (p<0,05) gewigstoename van 0,72 / 0,32 g gehad teenoor die tilapia in die drywende hokstesel 1,40 / 0,24 g en 1,20 / 0,15 g van die tilapia in die hersirkuleringseenheid. Tilapia in die gronddamme het dus ongeveer 45% swakker gemiddelde gewigstoename getoon as die van die drywende hokstelsel en hersirkuleringseenheid. Die produksiestelsel het 'n hoogs betekenisvolle invloed (p<0,001) op die groeipotensiaal van tilapia gehad in hierdie studie. Die gemiddelde totale hoeveelheid voer verbruik was nie statisties verskillend tussen die drywende hokstelsel en gronddam stelsel nie (29,83 / 2,66 vs 30,83 / 5,42), maar wel (p<0,05) vir die hersirkuleringseenheid (29,94 / 0,88). Die VOV het nie verskil tussen die drywende hokstelsel en hersirkuleringeenheid, maar daar was wel 'n verskil (p<0,05) tussen hierdie twee stelsels en die van die gronddamme. Die totale gemiddelde mortaliteite van tilapia was die hoogste (p<0,05) vir die drywende hokstelsel in vergelyking met die gronddamme en hersirkuleringseenheid. Die drywende hokstelsel het 14,67 / 14,61% meer mortaliteite gehad as die gronddamme en hersirkuleringeenheid. Die koi studie se resultate dui aan dat die tipe stelsel het 'n hoogs betekenisvolle (p<0,001) invloed gehad op die gemiddelde toename in lengte van die koi vis vir die somerseisoen. Die tipe dieet het geen invloed op die toename in lengte van koi vis vir al drie die stelsels ge-evalueer, maar die interaksie tussen dieet en die tipe stelsel was wel betekenisvol (p<0.05). Die interaksie tussen die tipe dieet en die tipe stelsel was die hoogste vir die groddamme 136,41 / 32,46 mm en 136,25 / 33,08 mm vir beide tilapia en die koi diëte gevoer. Die gemiddelde totale voer wat deur koi visse in die drie stelsels verbruik is, het wel statisties van mekaar verskil (p<0,05). Koi visse in die gronddam stelsel het meer voer verbruik vir beide die tilapia- en koi dieet (31,03 / 2,01 en 29,67 / 3,57) in vergelyking met die (26,35 / 2,44 ; 26,98 / 0,49 en 5,50 # 0,52 en 6,13 / 0,22) vir die drywende hokke en hersirkuleringseenheid stelsels onderskiedelik. Die % mortaliteite was betekenisvol (p<0,05) vir die verskillende stelsels. Koi visse in die hersirkuleringseenheid het die hoogste mortaliteite gehad vir beide die tilapia en die koi diëte (65,50 / 18,07% en 79,50 / 38,27%) terwyl koi visse in die gronddamme die laagste mortaliteite ondervind het (1,20 / 1,20% en 2,33 / 4,89%) vir beide die tilapia en koi diëte. Die koi in die gronddam stelsel het die beste resultate gelewer en dit is ook moontlik om koi 'n lae waarde dieet te voer sonder nadelige effekte op produksie.
- Full Text:
- Date Issued: 2002
'Me Maria, re adora
- Performer not specified, Ramashapole, Michael Naper, Juliet, S. C. O., Sister, Dargie, Dave
- Authors: Performer not specified , Ramashapole, Michael Naper , Juliet, S. C. O., Sister , Dargie, Dave
- Date: 1984
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Lesotho Hlotse f-lo
- Language: Sesotho
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/291417 , vital:56856 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD084-01
- Description: Compositions performed by the congregation in the Church at Hlotse with clapping accompaniment.
- Full Text: false
- Date Issued: 1984
- Authors: Performer not specified , Ramashapole, Michael Naper , Juliet, S. C. O., Sister , Dargie, Dave
- Date: 1984
- Subjects: Folk music , Field recordings , Africa, Sub-Saharan , Africa Lesotho Hlotse f-lo
- Language: Sesotho
- Type: sound recordings , field recordings , sound recording-musical
- Identifier: http://hdl.handle.net/10962/291417 , vital:56856 , International Library of African Music, Rhodes University, Makhanda, South Africa , Dave Dargie Field Tapes, Rhodes University, Makhanda, South Africa , DD084-01
- Description: Compositions performed by the congregation in the Church at Hlotse with clapping accompaniment.
- Full Text: false
- Date Issued: 1984
An assessment of the nutritional status of young black school children in the Albany Magisterial District, Eastern Cape
- Authors: Fincham, Robert John
- Date: 1981
- Subjects: Schools -- South Africa -- Grahamstown Africans -- Nutrition Nutrition surveys -- South Africa -- Eastern Cape Malnutrition -- South Africa -- Eastern Cape Children -- South Africa -- Nutrition
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2172 , vital:20262 , ISBN 0868100773
- Description: This working paper covers a survey conducted between 16 and 30 January 1980 of 3 171 black Sub A and Sub B pupils 8 years old or younger, at schools in both the rural and urban areas of the Albany Magisterial District, Eastern Cape. The survey, under the auspices of the Institute of Social and Economic Research (ISER), Rhodes University, was carried out as a result of a request from Dr J. D. Krynauw, Regional Director of Health Services in the Eastern Cape, to assess levels of nutrition of black children. Newspaper reports (see Appendix 1) of low levels of nutrition and high infant mortality rates among young black children in the Eastern Cape appeared to suggest a chronic nutritional situation, a situation not perceived as such by the Department of Health. A comprehensive pilot study was instituted on written request from Dr Krynauw in late October 1979. A report of the pilot study findings was presented in May 1980 to the Department of Health (Fincham, 1980). The present paper elaborates on that report and also includes analyses of data not presented before. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1981
- Authors: Fincham, Robert John
- Date: 1981
- Subjects: Schools -- South Africa -- Grahamstown Africans -- Nutrition Nutrition surveys -- South Africa -- Eastern Cape Malnutrition -- South Africa -- Eastern Cape Children -- South Africa -- Nutrition
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2172 , vital:20262 , ISBN 0868100773
- Description: This working paper covers a survey conducted between 16 and 30 January 1980 of 3 171 black Sub A and Sub B pupils 8 years old or younger, at schools in both the rural and urban areas of the Albany Magisterial District, Eastern Cape. The survey, under the auspices of the Institute of Social and Economic Research (ISER), Rhodes University, was carried out as a result of a request from Dr J. D. Krynauw, Regional Director of Health Services in the Eastern Cape, to assess levels of nutrition of black children. Newspaper reports (see Appendix 1) of low levels of nutrition and high infant mortality rates among young black children in the Eastern Cape appeared to suggest a chronic nutritional situation, a situation not perceived as such by the Department of Health. A comprehensive pilot study was instituted on written request from Dr Krynauw in late October 1979. A report of the pilot study findings was presented in May 1980 to the Department of Health (Fincham, 1980). The present paper elaborates on that report and also includes analyses of data not presented before. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1981
Black urban employment and Coloured labour preference
- Bekker, S B, Coetzee, Johannes Hendrik
- Authors: Bekker, S B , Coetzee, Johannes Hendrik
- Date: 1980
- Subjects: Black people -- Employment -- South Africa -- Cape Town Colored people (South Africa) -- Employment -- South Africa -- Cape Town Labor supply -- South Africa -- Cape Town Health services administration -- South Africa
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2216 , vital:20266 , ISBN 0868100420
- Description: State control over the labour market usually results in the creation of different categories of labour, each having partial and unequal access to that market. In the Third World, typically, justification for control arises from an over-supply of unskilled rural labour and a small demand for such labour in the wage economy. To reduce massive urban unemployment, the state attempts to control the process of rural-urban migration by, inter alia, manipulating the labour market. ^ In South Africa, the civilised labour policy of the Pact government and the highly sophisticated system of black influx control introduced after the Second World War are two examples of such state control. In these cases, racial categories of labour, having differential access to the labour market, were created. The policy of Coloured Labour Preference is another South African example which is of particular interest since it is applied solely to one region of the Republic. Since 1962, when it was administratively coordinated for the first time, this policy has been applied in the Western Cape, a region comprising the 68 magisterial districts situated south-west of Port Elizabeth, Kimberley and the Orange River. In this region, black work-seekers' access to the labour market is severely curtailed. A series of regulations, particular to the Western Cape, are applied with the object of restricting the number of blacks resident in the region; denying blacks permanent rights of sojourn in the region; restricting the scope of employment for blacks in the region; and favouring coloured above black work-seekers throughout the region. In short, the policy aims to replace black by coloured labour and thereby aims to reduce to a minimum the number of blacks in the region. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1980
- Authors: Bekker, S B , Coetzee, Johannes Hendrik
- Date: 1980
- Subjects: Black people -- Employment -- South Africa -- Cape Town Colored people (South Africa) -- Employment -- South Africa -- Cape Town Labor supply -- South Africa -- Cape Town Health services administration -- South Africa
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2216 , vital:20266 , ISBN 0868100420
- Description: State control over the labour market usually results in the creation of different categories of labour, each having partial and unequal access to that market. In the Third World, typically, justification for control arises from an over-supply of unskilled rural labour and a small demand for such labour in the wage economy. To reduce massive urban unemployment, the state attempts to control the process of rural-urban migration by, inter alia, manipulating the labour market. ^ In South Africa, the civilised labour policy of the Pact government and the highly sophisticated system of black influx control introduced after the Second World War are two examples of such state control. In these cases, racial categories of labour, having differential access to the labour market, were created. The policy of Coloured Labour Preference is another South African example which is of particular interest since it is applied solely to one region of the Republic. Since 1962, when it was administratively coordinated for the first time, this policy has been applied in the Western Cape, a region comprising the 68 magisterial districts situated south-west of Port Elizabeth, Kimberley and the Orange River. In this region, black work-seekers' access to the labour market is severely curtailed. A series of regulations, particular to the Western Cape, are applied with the object of restricting the number of blacks resident in the region; denying blacks permanent rights of sojourn in the region; restricting the scope of employment for blacks in the region; and favouring coloured above black work-seekers throughout the region. In short, the policy aims to replace black by coloured labour and thereby aims to reduce to a minimum the number of blacks in the region. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1980
“She is my sister although she’s got factory faults”: a psychosocial study of Xhosa women’s sister-sister relationships
- Authors: Moifo, Hunadi Senkoane
- Date: 2017
- Subjects: Xhosa (African people) -- Rites and ceremonies , Xhosa (African people) -- Social life and customs , Sisters -- South Africa -- Case studies , Xhosa (African people) -- Psychology , Women, Black -- South Africa -- Eastern Cape -- Psychology , Women, Black -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/4443 , vital:20671
- Description: The current study examines the constructions that Black, Xhosa women from the working class and in middle adulthood draw on to make meaning of their sister-sister relationships. In addition to this, it aims to uncover their motivations for investing in these meanings. It makes use of a psychosocial theoretical framework that draws on discursive psychology and psychoanalysis. Discursive psychology is used to analyse the constructions the participants used to make meaning of their relationship, while psychoanalysis is used to interpret their investments in these constructions. Six participants were interviewed using semi-structured interviews. The findings emphasise the psychosocial nature of the participants’ sisterly relationships, as caught between ‘inner’ world of feelings and emotions and the ‘outer’ world of social practices and expectations. Their narratives pointed to the obligatory nature of the sister-sister relationship, which drives participants to downplay the hatred or dislike that is present in their relationship and to emphasise traditional scripts of helping each other, promoting solidarity amongst sisters and other women. The analysis highlights the ways in which the participants negotiate and express their gender roles through sistering, reinforcing and challenging the traditional view of femininity and as a result providing for multiple femininities. In addition to these, the findings show that women may choose specific narratives to construct their sister-sister relationships as they allow them to feel safe and in control of their lives. Using psychoanalysis alongside discursive psychology enables the findings to illustrate how the participants invest in different constructions of their relationship in ways that are influenced by their values and life histories.
- Full Text:
- Date Issued: 2017
- Authors: Moifo, Hunadi Senkoane
- Date: 2017
- Subjects: Xhosa (African people) -- Rites and ceremonies , Xhosa (African people) -- Social life and customs , Sisters -- South Africa -- Case studies , Xhosa (African people) -- Psychology , Women, Black -- South Africa -- Eastern Cape -- Psychology , Women, Black -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/4443 , vital:20671
- Description: The current study examines the constructions that Black, Xhosa women from the working class and in middle adulthood draw on to make meaning of their sister-sister relationships. In addition to this, it aims to uncover their motivations for investing in these meanings. It makes use of a psychosocial theoretical framework that draws on discursive psychology and psychoanalysis. Discursive psychology is used to analyse the constructions the participants used to make meaning of their relationship, while psychoanalysis is used to interpret their investments in these constructions. Six participants were interviewed using semi-structured interviews. The findings emphasise the psychosocial nature of the participants’ sisterly relationships, as caught between ‘inner’ world of feelings and emotions and the ‘outer’ world of social practices and expectations. Their narratives pointed to the obligatory nature of the sister-sister relationship, which drives participants to downplay the hatred or dislike that is present in their relationship and to emphasise traditional scripts of helping each other, promoting solidarity amongst sisters and other women. The analysis highlights the ways in which the participants negotiate and express their gender roles through sistering, reinforcing and challenging the traditional view of femininity and as a result providing for multiple femininities. In addition to these, the findings show that women may choose specific narratives to construct their sister-sister relationships as they allow them to feel safe and in control of their lives. Using psychoanalysis alongside discursive psychology enables the findings to illustrate how the participants invest in different constructions of their relationship in ways that are influenced by their values and life histories.
- Full Text:
- Date Issued: 2017
A multi-threading software countermeasure to mitigate side channel analysis in the time domain
- Authors: Frieslaar, Ibraheem
- Date: 2019
- Subjects: Computer security , Data encryption (Computer science) , Noise generators (Electronics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71152 , vital:29790
- Description: This research is the first of its kind to investigate the utilisation of a multi-threading software-based countermeasure to mitigate Side Channel Analysis (SCA) attacks, with a particular focus on the AES-128 cryptographic algorithm. This investigation is novel, as there has not been a software-based countermeasure relying on multi-threading to our knowledge. The research has been tested on the Atmel microcontrollers, as well as a more fully featured system in the form of the popular Raspberry Pi that utilises the ARM7 processor. The main contributions of this research is the introduction of a multi-threading software based countermeasure used to mitigate SCA attacks on both an embedded device and a Raspberry Pi. These threads are comprised of various mathematical operations which are utilised to generate electromagnetic (EM) noise resulting in the obfuscation of the execution of the AES-128 algorithm. A novel EM noise generator known as the FRIES noise generator is implemented to obfuscate data captured in the EM field. FRIES comprises of hiding the execution of AES-128 algorithm within the EM noise generated by the 512 Secure Hash Algorithm (SHA) from the libcrypto++ and OpenSSL libraries. In order to evaluate the proposed countermeasure, a novel attack methodology was developed where the entire secret AES-128 encryption key was recovered from a Raspberry Pi, which has not been achieved before. The FRIES noise generator was pitted against this new attack vector and other known noise generators. The results exhibited that the FRIES noise generator withstood this attack whilst other existing techniques still leaked out secret information. The visual location of the AES-128 encryption algorithm in the EM spectrum and key recovery was prevented. These results demonstrated that the proposed multi-threading software based countermeasure was able to be resistant to existing and new forms of attacks, thus verifying that a multi-threading software based countermeasure can serve to mitigate SCA attacks.
- Full Text:
- Date Issued: 2019
- Authors: Frieslaar, Ibraheem
- Date: 2019
- Subjects: Computer security , Data encryption (Computer science) , Noise generators (Electronics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71152 , vital:29790
- Description: This research is the first of its kind to investigate the utilisation of a multi-threading software-based countermeasure to mitigate Side Channel Analysis (SCA) attacks, with a particular focus on the AES-128 cryptographic algorithm. This investigation is novel, as there has not been a software-based countermeasure relying on multi-threading to our knowledge. The research has been tested on the Atmel microcontrollers, as well as a more fully featured system in the form of the popular Raspberry Pi that utilises the ARM7 processor. The main contributions of this research is the introduction of a multi-threading software based countermeasure used to mitigate SCA attacks on both an embedded device and a Raspberry Pi. These threads are comprised of various mathematical operations which are utilised to generate electromagnetic (EM) noise resulting in the obfuscation of the execution of the AES-128 algorithm. A novel EM noise generator known as the FRIES noise generator is implemented to obfuscate data captured in the EM field. FRIES comprises of hiding the execution of AES-128 algorithm within the EM noise generated by the 512 Secure Hash Algorithm (SHA) from the libcrypto++ and OpenSSL libraries. In order to evaluate the proposed countermeasure, a novel attack methodology was developed where the entire secret AES-128 encryption key was recovered from a Raspberry Pi, which has not been achieved before. The FRIES noise generator was pitted against this new attack vector and other known noise generators. The results exhibited that the FRIES noise generator withstood this attack whilst other existing techniques still leaked out secret information. The visual location of the AES-128 encryption algorithm in the EM spectrum and key recovery was prevented. These results demonstrated that the proposed multi-threading software based countermeasure was able to be resistant to existing and new forms of attacks, thus verifying that a multi-threading software based countermeasure can serve to mitigate SCA attacks.
- Full Text:
- Date Issued: 2019
The synthesis, empirical and theoretical studies of various (N→B) diarylborinate esters
- Authors: Manana, Pholani Sakhile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53869 , vital:46027
- Description: A series of core-functionalized borinic acids was synthesized from Grignard reagents and tributylborate and reacted with ethanolamine, amino acids, 2-pyridylmethanol as well as 2-(ethyl amino ethanol). Among the borinic acids synthesized were the ones bearing: para-(2, 15, 16, 22, 27)-methyl, (3, 20, 25)-chloro, (4, 23, 26)-fluoro, (5)-methoxy; meta-(7, 17)-methyl, (9)-fluoro; ortho-(6)-methyl, (8)-chloro, (10, 18, 19)-methoxy substituents on their respective aromatic systems. All compounds obtained by condensation of the borinic acids with the aforementioned nitrogen-containing substrates were characterized structurally by means of diffraction studies based on single crystals and found to constitute chelate esters/amides featuring covalent B-O and dative N→B bonds. The chelate compounds researched in this study could be classified into four families and represent the compounds: ethanol amine: (1) 2,2-diphenyl-1,3,2-oxazaborolidines, (2) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (3) 2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (4) 2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (5) 2,2-bis(p-methoxyphenyl)-1,3,2-oxazaborolidines, (6) 2,2-bis(o-tolyl)-1,3,2-oxazaborolidines, (7) 2,2-bis(m-tolyl)-1,3,2-oxazaborolidines, (8) 2,2-bis(o-chlorophenyl)-1,3,2-oxazaborolidines, (9) 2,2-bis(m-fluorophenyl)-1,3,2-oxazaborolidines, (10) 2,2-bis(o-methoxyphenyl)-1,3,2-oxazaborolidines. α-amino acids : (14) 4-methyl-2,2-diphenyl-1,3,2-oxazaborolidin-5-ones, (15) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (16) 4-methyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (17) 4-isopropyl-2,2-bis(m-tolyl)-1,3,2-oxazaborolidin-5-ones, (18) 4-methyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (19) 4-acetamidyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (20) 4-phenylethane-2,2-bis(p-chlorophenyl)-1,3,2 oxazaborolidin-5-ones. 2-pyridylmethanol: (21) 1,3-hydroxypyridyl-2,2-diphenyl 1,3,2-oxazaborolidines, (22) 1,3-hydroxypyridyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (23) 1,3-hydroxypyridyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines 2-(ethyl amino ethanol): (24) 3-ethyl-2,2-diphenyl-1,3,2-oxazaborolidines, (25) 3-ethyl-2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (26) 3-ethyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (27) 3-ethyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines. Apart from structural studies in the solid state, the compounds were also characterized by means of multinuclear NMR spectroscopy (1H, 11B, 13C) as well as UV/vis and FTIR. The typical 11B resonances were found in the range of (4-10 ppm). A series of characteristic metrical parameters for the compounds in the solid state as well as typical NMR shifts for the chelate target molecules was established that allowed for the determination of the coordination induced shift. The carbon atom bonded to the oxygen atom shifted upfield, while the carbon atom bonded to the nitrogen atom shifted downfield. Factors mentioned in the literature that has an influence on the hydrolytic stability on the heterocyclic borinate motif have been taken into consideration and verified for the systems researched in this study. The substitution at the nitrogen atom with one ethyl group caused the greatest increases in the N→B bond length (27) 1.714 Å, due to the increase in the nitrogen Lewis basicity, making it the least hydrolytically stable, these include compounds (24-26). Furthermore, DFT calculations were performed by employing Becke’s three parameter hybrid exchange functional with Lee–Yang–Parr functional (B3LYP) method using the Gaussian 16 program package (Rev. B01) employing the basis set 6-311++G(d,p), to corroborate and correlate the experimental findings, which gave a general R-squared value of 0.9978 for calculated vs experimental 13C chemical shifts. Thermal properties are recorded for select compounds, indicating the ΔH and the melting points. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Manana, Pholani Sakhile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53869 , vital:46027
- Description: A series of core-functionalized borinic acids was synthesized from Grignard reagents and tributylborate and reacted with ethanolamine, amino acids, 2-pyridylmethanol as well as 2-(ethyl amino ethanol). Among the borinic acids synthesized were the ones bearing: para-(2, 15, 16, 22, 27)-methyl, (3, 20, 25)-chloro, (4, 23, 26)-fluoro, (5)-methoxy; meta-(7, 17)-methyl, (9)-fluoro; ortho-(6)-methyl, (8)-chloro, (10, 18, 19)-methoxy substituents on their respective aromatic systems. All compounds obtained by condensation of the borinic acids with the aforementioned nitrogen-containing substrates were characterized structurally by means of diffraction studies based on single crystals and found to constitute chelate esters/amides featuring covalent B-O and dative N→B bonds. The chelate compounds researched in this study could be classified into four families and represent the compounds: ethanol amine: (1) 2,2-diphenyl-1,3,2-oxazaborolidines, (2) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (3) 2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (4) 2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (5) 2,2-bis(p-methoxyphenyl)-1,3,2-oxazaborolidines, (6) 2,2-bis(o-tolyl)-1,3,2-oxazaborolidines, (7) 2,2-bis(m-tolyl)-1,3,2-oxazaborolidines, (8) 2,2-bis(o-chlorophenyl)-1,3,2-oxazaborolidines, (9) 2,2-bis(m-fluorophenyl)-1,3,2-oxazaborolidines, (10) 2,2-bis(o-methoxyphenyl)-1,3,2-oxazaborolidines. α-amino acids : (14) 4-methyl-2,2-diphenyl-1,3,2-oxazaborolidin-5-ones, (15) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (16) 4-methyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (17) 4-isopropyl-2,2-bis(m-tolyl)-1,3,2-oxazaborolidin-5-ones, (18) 4-methyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (19) 4-acetamidyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (20) 4-phenylethane-2,2-bis(p-chlorophenyl)-1,3,2 oxazaborolidin-5-ones. 2-pyridylmethanol: (21) 1,3-hydroxypyridyl-2,2-diphenyl 1,3,2-oxazaborolidines, (22) 1,3-hydroxypyridyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (23) 1,3-hydroxypyridyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines 2-(ethyl amino ethanol): (24) 3-ethyl-2,2-diphenyl-1,3,2-oxazaborolidines, (25) 3-ethyl-2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (26) 3-ethyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (27) 3-ethyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines. Apart from structural studies in the solid state, the compounds were also characterized by means of multinuclear NMR spectroscopy (1H, 11B, 13C) as well as UV/vis and FTIR. The typical 11B resonances were found in the range of (4-10 ppm). A series of characteristic metrical parameters for the compounds in the solid state as well as typical NMR shifts for the chelate target molecules was established that allowed for the determination of the coordination induced shift. The carbon atom bonded to the oxygen atom shifted upfield, while the carbon atom bonded to the nitrogen atom shifted downfield. Factors mentioned in the literature that has an influence on the hydrolytic stability on the heterocyclic borinate motif have been taken into consideration and verified for the systems researched in this study. The substitution at the nitrogen atom with one ethyl group caused the greatest increases in the N→B bond length (27) 1.714 Å, due to the increase in the nitrogen Lewis basicity, making it the least hydrolytically stable, these include compounds (24-26). Furthermore, DFT calculations were performed by employing Becke’s three parameter hybrid exchange functional with Lee–Yang–Parr functional (B3LYP) method using the Gaussian 16 program package (Rev. B01) employing the basis set 6-311++G(d,p), to corroborate and correlate the experimental findings, which gave a general R-squared value of 0.9978 for calculated vs experimental 13C chemical shifts. Thermal properties are recorded for select compounds, indicating the ΔH and the melting points. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text:
- Date Issued: 2021-12
From frontier to midlands: a history of the Graaff-Reinet district, 1786-1910
- Authors: Smith, Kenneth Wyndham
- Date: 1976
- Subjects: Graaff-Reinet (South Africa) -- History
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2656 , vital:20313 , ISBN 0949980730
- Description: The study of local history in South Africa is still in its infancy and has not been accorded the same recognition as elsewhere. There is no convenient manual to guide the would-be local historian of the Cape. There are few models that provide an insight into the main problems encountered by the local historian of a Cape community. In such local histories as exist, attention has been focussed predominantly on the foundation and physical growth of towns, the naming of streets, the establishment of schools and hospitals. Many of these accounts were written for publicity purposes or to commemorate the founding of towns. Although there is no history of the Dutch Reformed Church in Graaff-Reinet, the history of local congregations of the Dutch Reformed Church has generally been well covered in the form of Gedenkboeke and other studies. These frequently have a particular relevance as many towns such as Burgersdorp and Colesberg were founded as a result of the initiative of the church. Preface. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1976
- Authors: Smith, Kenneth Wyndham
- Date: 1976
- Subjects: Graaff-Reinet (South Africa) -- History
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2656 , vital:20313 , ISBN 0949980730
- Description: The study of local history in South Africa is still in its infancy and has not been accorded the same recognition as elsewhere. There is no convenient manual to guide the would-be local historian of the Cape. There are few models that provide an insight into the main problems encountered by the local historian of a Cape community. In such local histories as exist, attention has been focussed predominantly on the foundation and physical growth of towns, the naming of streets, the establishment of schools and hospitals. Many of these accounts were written for publicity purposes or to commemorate the founding of towns. Although there is no history of the Dutch Reformed Church in Graaff-Reinet, the history of local congregations of the Dutch Reformed Church has generally been well covered in the form of Gedenkboeke and other studies. These frequently have a particular relevance as many towns such as Burgersdorp and Colesberg were founded as a result of the initiative of the church. Preface. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1976
A socio-economic survey of the Amatola Basin: interim report
- Bekker, S B, de Wet, Christopher J, Manona, Cecil W
- Authors: Bekker, S B , de Wet, Christopher J , Manona, Cecil W
- Date: 1981
- Subjects: Ciskei (South Africa) -- Rural conditions Agriculture -- South Africa -- Ciskei Middledrift (South Africa) Fingo (African people) Hlubi (African people) Agriculture -- South Africa -- Ciskei Amatola River Watershed (South Africa) -- Economic conditions Amatola River Watershed (South Africa) -- Social conditions
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2282 , vital:20272 , ISBN 0868100730
- Description: Early in 1981, Professor S. Bekker of Rhodes University was invited to attend a meeting of the Amatola Basin Steering Committee of the Agricultural and Rural Development Research Institute (ARDRI) at the University of Fort Hare. At this meeting, Professor Bekker was invited to undertake a socio-economic survey of the Amatola Basin. The Board of the Institute of Social and Economic Research at Rhodes University gave Professor Bekker permission in February 1981 to undertake the research project on condition that it was conducted in the fashion this Institute usually requires. It was subsequently agreed that the survey, known as 'Amatola Basin VII: Socio-economic survey', was to establish the basic demographic, kinship, consumption and employment patterns of the residents of the Amatola Basin. Practices and traditions related to dry land agriculture would also be identified , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1981
- Authors: Bekker, S B , de Wet, Christopher J , Manona, Cecil W
- Date: 1981
- Subjects: Ciskei (South Africa) -- Rural conditions Agriculture -- South Africa -- Ciskei Middledrift (South Africa) Fingo (African people) Hlubi (African people) Agriculture -- South Africa -- Ciskei Amatola River Watershed (South Africa) -- Economic conditions Amatola River Watershed (South Africa) -- Social conditions
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2282 , vital:20272 , ISBN 0868100730
- Description: Early in 1981, Professor S. Bekker of Rhodes University was invited to attend a meeting of the Amatola Basin Steering Committee of the Agricultural and Rural Development Research Institute (ARDRI) at the University of Fort Hare. At this meeting, Professor Bekker was invited to undertake a socio-economic survey of the Amatola Basin. The Board of the Institute of Social and Economic Research at Rhodes University gave Professor Bekker permission in February 1981 to undertake the research project on condition that it was conducted in the fashion this Institute usually requires. It was subsequently agreed that the survey, known as 'Amatola Basin VII: Socio-economic survey', was to establish the basic demographic, kinship, consumption and employment patterns of the residents of the Amatola Basin. Practices and traditions related to dry land agriculture would also be identified , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1981
Genetic diversity, evolutionary relationships and conservation of southern African Labeo fishes in relation to water management
- Authors: Ramoejane, Mpho
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5209 , vital:20786
- Description: Labeo spp. are large, herbivorous fishes that are important components of aquatic ecosystems and are a high conservation priority in South Africa. This thesis contributes to determination of conservation priorities for Labeo umbratus (Smith 1841) by resolving the taxonomic status of this species in the evolutionary context of southern African Labeo spp., assessing the presence of unique lineages in historically isolated river basins, and assessing the threat of intra- and interspecific hybridisation associated with introductions. Phylogenetic analyses of five DNA sequence data sets (cytochrome c oxidase subunit I gene [COI], cytochrome b gene [Cyt b], Recombination activating gene 1 [Rag1], COI+Rag1 and COI+Cyt b+Rag1) showed that the Labeo umbratus group (sensu Reid, 1985), which comprises the species Labeo umbratus, Labeo capensis (Smith 1841), Labeo seeberi Gilchrist and Thompson 1911 and Labeo rubromaculatus Gilchrist and Thompson 1913, is monophyletic, morphologically distinct and geographically disjunct from other African Labeo spp. groups except in the Tugela River system were L. rubromaculatus co-occurs with Labeo molybdinus Du Plessis 1963. Phylogeographic analysis of mitochondrial DNA (Cyt b) sequence data demonstrated that the populations of the L. umbratus from the Orange and the southward-flowing river systems are reciprocally monophyletic and were identified as evolutionary significant units. The populations in the southward-flowing river systems were further divided into southwestern (Gourits and Gamtoos) and southeastern (Sundays, Bushmans, Great Fish, Keiskamma, Buffalo and Nahoon) polyp hyletic sublineages. Four management units (Gourits Basin; Gamtoos Basin; Sundays+Bushmans+Great Fish River Basins; and Keiskamma+Buffalo+Nahoon River Basin) were not reciprocally monophyletic but were proposed on the basis of containing unique haplotype frequencies for conservation purposes. To evaluate the threat of hybridisation to the genetic integrity of L. umbratus, the occurrence of Labeo umbratus x L. capensis hybrids was investigated using mtDNA Cyt b and nDNA S7 intron sequence data and morphological data. Genetic evidence for interspecific hybridisation was detected for populations in two impoundments, Hardap Dam (Orange River Basin) and Darlington Dam (Sundays River Basin, Eastern Cape, South Africa). Some putative hybrids were identifiable morphologically on account of intermediacy between the parental species in meristic and morphometric characters. Translocation via direct stocking (Hardap Dam) or via an inter-basin water transfer scheme (Darlington Dam) was identified as a driver for hybridisation. Introductions associated with an inter-basin water transfer scheme has resulted in introgression between the previously isolated Orange River and southern lineages of L. umbratus. Further translocation of fish from these affected areas to non-contaminated river systems and impoundments such as Kat River (Great Fish River) and Slagboom (Sundays River) should be avoided.
- Full Text:
- Date Issued: 2017
- Authors: Ramoejane, Mpho
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5209 , vital:20786
- Description: Labeo spp. are large, herbivorous fishes that are important components of aquatic ecosystems and are a high conservation priority in South Africa. This thesis contributes to determination of conservation priorities for Labeo umbratus (Smith 1841) by resolving the taxonomic status of this species in the evolutionary context of southern African Labeo spp., assessing the presence of unique lineages in historically isolated river basins, and assessing the threat of intra- and interspecific hybridisation associated with introductions. Phylogenetic analyses of five DNA sequence data sets (cytochrome c oxidase subunit I gene [COI], cytochrome b gene [Cyt b], Recombination activating gene 1 [Rag1], COI+Rag1 and COI+Cyt b+Rag1) showed that the Labeo umbratus group (sensu Reid, 1985), which comprises the species Labeo umbratus, Labeo capensis (Smith 1841), Labeo seeberi Gilchrist and Thompson 1911 and Labeo rubromaculatus Gilchrist and Thompson 1913, is monophyletic, morphologically distinct and geographically disjunct from other African Labeo spp. groups except in the Tugela River system were L. rubromaculatus co-occurs with Labeo molybdinus Du Plessis 1963. Phylogeographic analysis of mitochondrial DNA (Cyt b) sequence data demonstrated that the populations of the L. umbratus from the Orange and the southward-flowing river systems are reciprocally monophyletic and were identified as evolutionary significant units. The populations in the southward-flowing river systems were further divided into southwestern (Gourits and Gamtoos) and southeastern (Sundays, Bushmans, Great Fish, Keiskamma, Buffalo and Nahoon) polyp hyletic sublineages. Four management units (Gourits Basin; Gamtoos Basin; Sundays+Bushmans+Great Fish River Basins; and Keiskamma+Buffalo+Nahoon River Basin) were not reciprocally monophyletic but were proposed on the basis of containing unique haplotype frequencies for conservation purposes. To evaluate the threat of hybridisation to the genetic integrity of L. umbratus, the occurrence of Labeo umbratus x L. capensis hybrids was investigated using mtDNA Cyt b and nDNA S7 intron sequence data and morphological data. Genetic evidence for interspecific hybridisation was detected for populations in two impoundments, Hardap Dam (Orange River Basin) and Darlington Dam (Sundays River Basin, Eastern Cape, South Africa). Some putative hybrids were identifiable morphologically on account of intermediacy between the parental species in meristic and morphometric characters. Translocation via direct stocking (Hardap Dam) or via an inter-basin water transfer scheme (Darlington Dam) was identified as a driver for hybridisation. Introductions associated with an inter-basin water transfer scheme has resulted in introgression between the previously isolated Orange River and southern lineages of L. umbratus. Further translocation of fish from these affected areas to non-contaminated river systems and impoundments such as Kat River (Great Fish River) and Slagboom (Sundays River) should be avoided.
- Full Text:
- Date Issued: 2017
Maputo declaration on the textiles, clothing and leather industries
- Authors: Worker representatives
- Date: 1999?
- Subjects: Clothing trade , Textile industry , Leather industry and trade , Complaints (Civil procedure)
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/76004 , vital:30491
- Description: The massive job losses and factory closures in the clothing, textiles and leather industries in almost all countries in the region. The low wages that continue in our industries, resulting in a low and, in many instances, declining standard of living of workers. The crisis which face unemployed workers who have no income, no social security net, and no immediate prospect of a job. It is a fundamental responsibility of governments in the region to work with trade unions and employers in order to develop appropriate policies to secure a future for the industries and to improve the conditions of workers.
- Full Text:
- Date Issued: 1999?
- Authors: Worker representatives
- Date: 1999?
- Subjects: Clothing trade , Textile industry , Leather industry and trade , Complaints (Civil procedure)
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/76004 , vital:30491
- Description: The massive job losses and factory closures in the clothing, textiles and leather industries in almost all countries in the region. The low wages that continue in our industries, resulting in a low and, in many instances, declining standard of living of workers. The crisis which face unemployed workers who have no income, no social security net, and no immediate prospect of a job. It is a fundamental responsibility of governments in the region to work with trade unions and employers in order to develop appropriate policies to secure a future for the industries and to improve the conditions of workers.
- Full Text:
- Date Issued: 1999?
Fungal remediation of winery and distillery wastewaters using Trametes pubescens MB 89 and the enhanced production of a high-value enzyme therein
- Authors: Strong, Peter James
- Date: 2008
- Subjects: Fungal remediation Distilleries -- Waste disposal Wine and wine making -- Waste disposal Bioremediation Laccase Enzymes -- Biotechnology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3932 , http://hdl.handle.net/10962/d1003991
- Description: In this study white-rot fungi were investigated for their efficiency at distillery wastewater remediation and the production of laccase as a valuable by-product. Distillery wastewaters are high in organic load and low in pH. The presence of phenolic compounds can lead to extremely colour-rich wastewaters and can be toxic to microorganisms. The presence of the inorganic ions may also affect biological treatment. White-rot fungi are unique among eukaryotic or prokaryotic microbes in possessing powerful oxidative enzyme systems that can degrade lignin to carbon dioxide. These ligninolytic enzymes, such as lignin peroxidase, manganese peroxidase and laccase, are capable of degrading a vast range of toxic, recalcitrant environmental pollutants and this makes the white-rot fungi strong candidates for the bioremediation of polluted soils and waters. The laccase enzyme alone has shown remediation potential in wastewaters such as beer production effluent, olive mill wastewater, alcohol distillery wastes, dye-containing wastewaters from the textile industry as well as wastewaters from the paper and pulp industry. It has been shown to be capable of remediating soils and waters polluted with chlorinated phenolic compounds, polyaromatic hydrocarbons, nitrosubstituted compounds and fungicides, herbicides and insecticides.
- Full Text:
- Date Issued: 2008
- Authors: Strong, Peter James
- Date: 2008
- Subjects: Fungal remediation Distilleries -- Waste disposal Wine and wine making -- Waste disposal Bioremediation Laccase Enzymes -- Biotechnology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3932 , http://hdl.handle.net/10962/d1003991
- Description: In this study white-rot fungi were investigated for their efficiency at distillery wastewater remediation and the production of laccase as a valuable by-product. Distillery wastewaters are high in organic load and low in pH. The presence of phenolic compounds can lead to extremely colour-rich wastewaters and can be toxic to microorganisms. The presence of the inorganic ions may also affect biological treatment. White-rot fungi are unique among eukaryotic or prokaryotic microbes in possessing powerful oxidative enzyme systems that can degrade lignin to carbon dioxide. These ligninolytic enzymes, such as lignin peroxidase, manganese peroxidase and laccase, are capable of degrading a vast range of toxic, recalcitrant environmental pollutants and this makes the white-rot fungi strong candidates for the bioremediation of polluted soils and waters. The laccase enzyme alone has shown remediation potential in wastewaters such as beer production effluent, olive mill wastewater, alcohol distillery wastes, dye-containing wastewaters from the textile industry as well as wastewaters from the paper and pulp industry. It has been shown to be capable of remediating soils and waters polluted with chlorinated phenolic compounds, polyaromatic hydrocarbons, nitrosubstituted compounds and fungicides, herbicides and insecticides.
- Full Text:
- Date Issued: 2008
The life and work of Benjamin Tyamzashe: a contemporary Xhosa composer
- Authors: Hansen, Deirdre Doris
- Date: 1968
- Subjects: Xhosa (African people) -- Music , Hymns, Xhosa , Tyamzashe, Benjamin John Peter (1890-1978) , Composers, Black -- South Africa
- Language: English , Xhosa
- Type: Book
- Identifier: vital:550 , http://hdl.handle.net/10962/d1020214
- Description: The present paper is a digest of the thesis submitted under the same title, by Miss Deirdre Hansen for the Degree of Master of Music of Rhodes University in 1968. This work includes a large number of musical illustrations, which illuminate in detail many aspects of the works of Benjamin Tyamzashe. The section containing these has been reduced to its essentials, but what is here given should enable the reader to understand the manner in which Tyamzashe's ability as a composer has developed, and to give him his rightful place among his contemporaries. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1968
- Authors: Hansen, Deirdre Doris
- Date: 1968
- Subjects: Xhosa (African people) -- Music , Hymns, Xhosa , Tyamzashe, Benjamin John Peter (1890-1978) , Composers, Black -- South Africa
- Language: English , Xhosa
- Type: Book
- Identifier: vital:550 , http://hdl.handle.net/10962/d1020214
- Description: The present paper is a digest of the thesis submitted under the same title, by Miss Deirdre Hansen for the Degree of Master of Music of Rhodes University in 1968. This work includes a large number of musical illustrations, which illuminate in detail many aspects of the works of Benjamin Tyamzashe. The section containing these has been reduced to its essentials, but what is here given should enable the reader to understand the manner in which Tyamzashe's ability as a composer has developed, and to give him his rightful place among his contemporaries. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1968
Synthesis, characterization, and biological studies of pyrazolone Schiff bases and their transition metal complexes
- Authors: Idemudia, Omoruyi Gold
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11340 , http://hdl.handle.net/10353/d1016068
- Description: Some new acylpyrazolone Schiff bases have been synthesized from the condensation reaction of two acylpyrazolone diketone precursors with phenylhydrazine, 2,4-dinitrophenylhydrazine and sulfanilamide. They have been fully characterized by elemental analysis and spectroscopic techniques (IR,1H and 13C NMR, and mass-spectra). The single crystal structure of the benzoyl derivative acylpyrazolone Schiff bases have been obtained and analyzed by X-ray crystallography technique. Solid state X-ray diffraction revealed a keto tautomer Schiff base in solid state. Mn(II), Co(II), Ni(II) and Cu(II) complexes with the Schiff bases have been synthesized and characterized by elemental analysis, IR and UV-VIS spectroscopy, magnetic susceptibility measurements, and thermal studies (TGA and DTG). An octahedral geometry around the transition metal ion, consisting of two bidentate Schiff base ligands bonding through the azometine nitrogen and ketonic oxygen have been proposed based on careful interpretation of available analytical and spectroscopic characterization results. Two water molecules as ligands complete the octahedral geometry in all cases. Using the invitro disc diffusion method for screening synthesized compounds against selected gram positive and gram negative bacterial at 40 mg/mL, and the DPPH free radical scavenging methods at 0.50, 0.25 and 0.13 mg/mL, the synthesized Schiff base and metal complexes showed varying biological activities. 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one sul29 fanilamide showed more activity generally, exhibiting a broad spectrum activity against all selected bacterial in some cases. Mn(II), Co(II) and Ni(II) complexes of sulfanilamide Schiff base with the acetylpyrazolone derivative 4-acetyl-3-methyl-1-phenyl-2-pyrazolin-5-one sulfanilamide, exhibited a stronger and very good DPPH radical scavenging activity as good as ascorbic acid on comparing, but not with Cu(II). As such they could be important antitumour candidates.
- Full Text:
- Date Issued: 2014
- Authors: Idemudia, Omoruyi Gold
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11340 , http://hdl.handle.net/10353/d1016068
- Description: Some new acylpyrazolone Schiff bases have been synthesized from the condensation reaction of two acylpyrazolone diketone precursors with phenylhydrazine, 2,4-dinitrophenylhydrazine and sulfanilamide. They have been fully characterized by elemental analysis and spectroscopic techniques (IR,1H and 13C NMR, and mass-spectra). The single crystal structure of the benzoyl derivative acylpyrazolone Schiff bases have been obtained and analyzed by X-ray crystallography technique. Solid state X-ray diffraction revealed a keto tautomer Schiff base in solid state. Mn(II), Co(II), Ni(II) and Cu(II) complexes with the Schiff bases have been synthesized and characterized by elemental analysis, IR and UV-VIS spectroscopy, magnetic susceptibility measurements, and thermal studies (TGA and DTG). An octahedral geometry around the transition metal ion, consisting of two bidentate Schiff base ligands bonding through the azometine nitrogen and ketonic oxygen have been proposed based on careful interpretation of available analytical and spectroscopic characterization results. Two water molecules as ligands complete the octahedral geometry in all cases. Using the invitro disc diffusion method for screening synthesized compounds against selected gram positive and gram negative bacterial at 40 mg/mL, and the DPPH free radical scavenging methods at 0.50, 0.25 and 0.13 mg/mL, the synthesized Schiff base and metal complexes showed varying biological activities. 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one sul29 fanilamide showed more activity generally, exhibiting a broad spectrum activity against all selected bacterial in some cases. Mn(II), Co(II) and Ni(II) complexes of sulfanilamide Schiff base with the acetylpyrazolone derivative 4-acetyl-3-methyl-1-phenyl-2-pyrazolin-5-one sulfanilamide, exhibited a stronger and very good DPPH radical scavenging activity as good as ascorbic acid on comparing, but not with Cu(II). As such they could be important antitumour candidates.
- Full Text:
- Date Issued: 2014
Who goes to parliament?
- Authors: Stultz, Newell Maynard
- Date: 1975
- Subjects: Legislators -- South Africa South Africa -- Politics and government -- 1948-1994 South Africa -- Politics and government
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2747 , vital:20322 , ISBN 0949980560
- Description: The focus here is upon the 1 169 white men and the twelve white women who were elected or nominated to the South African Parliament in Cape Town between 1910 and the conclusion of the 1970 general and Senate elections.1 Because of the integrated nature of government at the national level in South Africa, an examination of all parliamentarians concurrently produces information on all cabinet ministers during the same period, and for most if not all of the top leaders of the major political parties as well. Hence, recognizing the unitary structure of the South African regime - sometimes expressed in the principle of the 'sovereignty of Parliament' - it seems possible to designate these 1 181 persons as the formally ascendant South African political elite during the country's first six decades. Moreover, there is no reason to doubt that this number includes nearly all of the persons who exercised disproportionately great real power during these years, excepting, of course, those few non-whites who may be thought to have been politically influential at the national level. Every indication is that political life in South Africa centred on these individuals, or at least on some of them, for clearly not all were of equal political importance. Yet even the leaders within this select group, whom we shall also consider separately in detail, frequently (although not in every case) rose to prominence within the institution of Parliament, in part on the basis of their ability to influence and control its deliberations. An understanding of the backgrounds of all parliamentarians thus not only helps to describe the body itself, but may also contribute a new appreciation of the political power of the country's top leadership. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1975
- Authors: Stultz, Newell Maynard
- Date: 1975
- Subjects: Legislators -- South Africa South Africa -- Politics and government -- 1948-1994 South Africa -- Politics and government
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2747 , vital:20322 , ISBN 0949980560
- Description: The focus here is upon the 1 169 white men and the twelve white women who were elected or nominated to the South African Parliament in Cape Town between 1910 and the conclusion of the 1970 general and Senate elections.1 Because of the integrated nature of government at the national level in South Africa, an examination of all parliamentarians concurrently produces information on all cabinet ministers during the same period, and for most if not all of the top leaders of the major political parties as well. Hence, recognizing the unitary structure of the South African regime - sometimes expressed in the principle of the 'sovereignty of Parliament' - it seems possible to designate these 1 181 persons as the formally ascendant South African political elite during the country's first six decades. Moreover, there is no reason to doubt that this number includes nearly all of the persons who exercised disproportionately great real power during these years, excepting, of course, those few non-whites who may be thought to have been politically influential at the national level. Every indication is that political life in South Africa centred on these individuals, or at least on some of them, for clearly not all were of equal political importance. Yet even the leaders within this select group, whom we shall also consider separately in detail, frequently (although not in every case) rose to prominence within the institution of Parliament, in part on the basis of their ability to influence and control its deliberations. An understanding of the backgrounds of all parliamentarians thus not only helps to describe the body itself, but may also contribute a new appreciation of the political power of the country's top leadership. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1975
Leadership development within a learner representative council: a Namibian primary school case study
- Authors: Tjihuro, Jaqueline
- Date: 2018
- Subjects: School management and organization Namibia , Educational leadership Namibia , Student participation in administration Namibia , Student government Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/61558 , vital:28036
- Description: Learners in Namibian primary schools are seemingly not brave enough to stand and raise their voice on issues that concern them. This is what Shekupakela-Nelulu (2008) wrote after a study she conducted on the Learners’ Representative Council (LRC) of a school in Namibia. She refers to a time when “the involvement of students in school affairs was seen by the regime as a political act and attempts by student leaders to involve themselves in educational issues were often quashed” (ibid., p. i). This situation will be all too familiar to South African readers, where a public holiday, Youth Day, was declared to mark the apartheid regime’s brutal treatment of learner protestors on June 16, 1976. While Namibia has not experienced events of such magnitude, the notion of learner voice is equally problematic and worthy of investigation. The absence of leadership development opportunities for learners has led to this research study which seeks to answer the central research question: How can learner leadership be developed in a LRC? I used an interpretive paradigm, adopting a qualitative approach in the study. Concurrently, the study was framed and guided by the second generation of Cultural Historical Activity Theory (CHAT) as an analytical tool to achieve my research goal. The following questions guided the study in two phases. Phase one: What were the perceived causes for the nonsustainability of the learner leadership (LL) club at the school? Phase two: How is the notion of learner leadership understood in the school? How is leadership developed on the LRC? What enables and constrains leadership development of learners on the LRC? The research participants were thirty LRC members from grades 6 and 7 and15 teachers who teach the LRC members. The principal and three HOD’s were also research participants being part of the Senior Management team. One of the HOD’s also fulfils the role of the guardian teacher to the LRC. A school board chairperson also participated in the Change Laboratory Workshop. Data was generated through multiple data sources such as questionnaires, individual interviews, a focus group interview and observation. The findings from phase one of the study revealed that the learner leadership club’s intervention was a success during the 2014 academic year, but the absence of the learner leadership club as an extra-mural activity affected the sustainability of the club into the next academic year 2015. Findings from phase two revealed that leadership opportunities did exist at the school for learner leadership development. However, a few challenges emerged relating to traditional views of leadership and constraining factors that could affect learner leadership development at the school. Thus, Change Laboratory workshops were held to find solutions to the challenges, in order to promote and enhance learner leadership development, hopefully for the future of the Namibian child.
- Full Text:
- Date Issued: 2018
Leadership development within a learner representative council: a Namibian primary school case study
- Authors: Tjihuro, Jaqueline
- Date: 2018
- Subjects: School management and organization Namibia , Educational leadership Namibia , Student participation in administration Namibia , Student government Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/61558 , vital:28036
- Description: Learners in Namibian primary schools are seemingly not brave enough to stand and raise their voice on issues that concern them. This is what Shekupakela-Nelulu (2008) wrote after a study she conducted on the Learners’ Representative Council (LRC) of a school in Namibia. She refers to a time when “the involvement of students in school affairs was seen by the regime as a political act and attempts by student leaders to involve themselves in educational issues were often quashed” (ibid., p. i). This situation will be all too familiar to South African readers, where a public holiday, Youth Day, was declared to mark the apartheid regime’s brutal treatment of learner protestors on June 16, 1976. While Namibia has not experienced events of such magnitude, the notion of learner voice is equally problematic and worthy of investigation. The absence of leadership development opportunities for learners has led to this research study which seeks to answer the central research question: How can learner leadership be developed in a LRC? I used an interpretive paradigm, adopting a qualitative approach in the study. Concurrently, the study was framed and guided by the second generation of Cultural Historical Activity Theory (CHAT) as an analytical tool to achieve my research goal. The following questions guided the study in two phases. Phase one: What were the perceived causes for the nonsustainability of the learner leadership (LL) club at the school? Phase two: How is the notion of learner leadership understood in the school? How is leadership developed on the LRC? What enables and constrains leadership development of learners on the LRC? The research participants were thirty LRC members from grades 6 and 7 and15 teachers who teach the LRC members. The principal and three HOD’s were also research participants being part of the Senior Management team. One of the HOD’s also fulfils the role of the guardian teacher to the LRC. A school board chairperson also participated in the Change Laboratory Workshop. Data was generated through multiple data sources such as questionnaires, individual interviews, a focus group interview and observation. The findings from phase one of the study revealed that the learner leadership club’s intervention was a success during the 2014 academic year, but the absence of the learner leadership club as an extra-mural activity affected the sustainability of the club into the next academic year 2015. Findings from phase two revealed that leadership opportunities did exist at the school for learner leadership development. However, a few challenges emerged relating to traditional views of leadership and constraining factors that could affect learner leadership development at the school. Thus, Change Laboratory workshops were held to find solutions to the challenges, in order to promote and enhance learner leadership development, hopefully for the future of the Namibian child.
- Full Text:
- Date Issued: 2018
Tetra 4-(propargyloxy)phenoxy phthalocyanines: synthesis, spectroscopic, nonlinear optical and electrocatalytic properties
- Authors: Mwanza, Daniel
- Date: 2017
- Subjects: Phthalocyanines , Nonlinear optics , Electrocatalysis , Spectrum analysis , Thermogravimetry , Phthalocyanines Spectra
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/65144 , vital:28695
- Description: This study presents the synthesis, spectroscopic, photophysical and theoretical characterisation of metal-free (H2TPrOPhOPc), cobalt (CoTPrOPhOPc) and manganese (MnTPrOPhOPc) tetra 4-(4-propargyloxy) phenoxy phthalocyanines. Thermal analysis using thermogravimetric analysis (TGA) confirmed the excellent thermal stability of synthesized tetra 4-(4- propargyloxy) phenoxy phthalocyanines. The metal complexes, CoTPrOPhOPc and MnTPrOPhOPc, exhibited better thermal stability when compared to H2TPrOPhOPc. The residual percentage weight remaining was approximately 70% for CoTPrOPhOPc and MnTPrOPhOPc and 45% for H2TPrOPhOPc after 600°C, clearly confirming the stability of the metal complexes. The MTPrOPhOPcs (where M = H2, Co and Mn) complexes exhibited excellent nonlinear optical properties with strong reverse saturable absorption (RSA), especially when 560 nm excitation laser was used. Their nonlinear optical properties followed this trend: H2TPrOPhOPc > CoTPrOPhOPc > MnTPrOPhOPc. According to the trend observed, the H2TPrOPhOPc was an excellent nonlinear optical limiter when compared to the CoTPrOPhOPc and MnTPrOPhOPc. All the investigated complexes exhibited optical limiting properties comparable to the phthalocyanine complexes reported in the literature. The MTPrOPhOPc complexes were further studied for their electrocatalytic and electroanalytical properties towards the detection of hydrogen peroxide. For the electrocatalytic studies, the synthesized complexes were immobilized onto gold electrode surfaces pre-functionalized with phenylazide (Au-PAz) monolayer. Copper (I) catalyzed alkynyl-azide cycloaddition reaction was used to covalently immobilize the MTPrOPhOPcs onto the gold electrode surfaces to form Au-PAz-MTPrOPhOPc. The MTPrOPhOPcs modified gold surfaces (Au-PAz-MTPrOPhOPc) exhibited good reproducibility and stability in various electrolyte conditions. Electrochemical and surface characterisation of the functionalised gold electrode surfaces confirmed the presence of the MTPrOPhOPcs and their electroanalysis was excellent towards electrocatalytic reduction of H2O2, with the limit of detection (LoD) and limit of quantification (LoQ) in the ^M range. The electrocatalytic reduction peaks for H2O2 were observed at -0.37 V for Au-PAz-MnTPrOPhOPc and -0.31 V for Au-PAz-CoTPrOPhOPc when Ag|AgCl pseudo-reference electrode was used. The Au-PAz-MnTPrOPhOPc and Au- PAz-CoTPrOPhOPc gold electrode surfaces showed good sensitivity and reproducibility towards the electrocatalytic reduction of hydrogen peroxide in pH 7.4 phosphate buffer solution. , Thesis (MSc) -- Faculty of Science, Chemistry, 2017
- Full Text:
- Date Issued: 2017
- Authors: Mwanza, Daniel
- Date: 2017
- Subjects: Phthalocyanines , Nonlinear optics , Electrocatalysis , Spectrum analysis , Thermogravimetry , Phthalocyanines Spectra
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/65144 , vital:28695
- Description: This study presents the synthesis, spectroscopic, photophysical and theoretical characterisation of metal-free (H2TPrOPhOPc), cobalt (CoTPrOPhOPc) and manganese (MnTPrOPhOPc) tetra 4-(4-propargyloxy) phenoxy phthalocyanines. Thermal analysis using thermogravimetric analysis (TGA) confirmed the excellent thermal stability of synthesized tetra 4-(4- propargyloxy) phenoxy phthalocyanines. The metal complexes, CoTPrOPhOPc and MnTPrOPhOPc, exhibited better thermal stability when compared to H2TPrOPhOPc. The residual percentage weight remaining was approximately 70% for CoTPrOPhOPc and MnTPrOPhOPc and 45% for H2TPrOPhOPc after 600°C, clearly confirming the stability of the metal complexes. The MTPrOPhOPcs (where M = H2, Co and Mn) complexes exhibited excellent nonlinear optical properties with strong reverse saturable absorption (RSA), especially when 560 nm excitation laser was used. Their nonlinear optical properties followed this trend: H2TPrOPhOPc > CoTPrOPhOPc > MnTPrOPhOPc. According to the trend observed, the H2TPrOPhOPc was an excellent nonlinear optical limiter when compared to the CoTPrOPhOPc and MnTPrOPhOPc. All the investigated complexes exhibited optical limiting properties comparable to the phthalocyanine complexes reported in the literature. The MTPrOPhOPc complexes were further studied for their electrocatalytic and electroanalytical properties towards the detection of hydrogen peroxide. For the electrocatalytic studies, the synthesized complexes were immobilized onto gold electrode surfaces pre-functionalized with phenylazide (Au-PAz) monolayer. Copper (I) catalyzed alkynyl-azide cycloaddition reaction was used to covalently immobilize the MTPrOPhOPcs onto the gold electrode surfaces to form Au-PAz-MTPrOPhOPc. The MTPrOPhOPcs modified gold surfaces (Au-PAz-MTPrOPhOPc) exhibited good reproducibility and stability in various electrolyte conditions. Electrochemical and surface characterisation of the functionalised gold electrode surfaces confirmed the presence of the MTPrOPhOPcs and their electroanalysis was excellent towards electrocatalytic reduction of H2O2, with the limit of detection (LoD) and limit of quantification (LoQ) in the ^M range. The electrocatalytic reduction peaks for H2O2 were observed at -0.37 V for Au-PAz-MnTPrOPhOPc and -0.31 V for Au-PAz-CoTPrOPhOPc when Ag|AgCl pseudo-reference electrode was used. The Au-PAz-MnTPrOPhOPc and Au- PAz-CoTPrOPhOPc gold electrode surfaces showed good sensitivity and reproducibility towards the electrocatalytic reduction of hydrogen peroxide in pH 7.4 phosphate buffer solution. , Thesis (MSc) -- Faculty of Science, Chemistry, 2017
- Full Text:
- Date Issued: 2017
BODIPY dyes for singlet oxygen and optical limiting applications
- Authors: Harris, Jessica
- Date: 2018
- Subjects: Photosensitizing compounds , Active oxygen -- Physiological effect , Photochemotherapy , Cancer -- Treatment , Nonlinear optics , BODIPY (Boron-dipyrromethene)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58002 , vital:27014
- Description: A series of structurally related BODIPY dyes were synthesised and characterised. Their photophysical properties were studied in order to determine whether they would be suitable candidates for use as photosensitisers in the photodynamic therapy (PDT) treatment of cancer. The synthesis of two highly fluorescent BODIPY cores was achieved via the acid-catalysed condensation of a pyrrole and a functionalised aldehyde. In order to promote intersystem crossing, and hence improve the singlet oxygen generation of these dyes, bromine atoms were added at the 2,6-positions of the BODIPY core. These dibrominated analogues showed good singlet oxygen quantum yields, and excellent photostability in ethanol. In order to red-shift the main spectral bands of the BODIPY dyes towards the therapeutic window, vinyl/ styryl groups were introduced at the 3-, 5-, and 7-positions via a modified Knoevengal condensation reaction. The addition of vinyl/ styryl groups to the BODIPY core caused an increase in fluorescence quantum yield as well as a decrease in singlet oxygen quantum yield with respect to the dibrominated analogues. However, two of the red-shifted BODIPY dyes still showed moderate singlet oxygen quantum yields. The use of BODIPY dyes in nonlinear optics (NLO) was explored. The nonlinear optical characterisations and optical limiting properties of a series of 3,5-dithienylenevinylene BODIPY dyes were studied, both in dimethylformamide (DMF) solution and when embedded in poly(bisphenol A carbonate) (PBC) as thin films. The 3,5-dithienylenevinylene BODIPY dyes showed typical nonlinear absorption behaviour, with reverse saturable absorption (RSA) profiles, indicating that they have potential as optical limiters. The second-order hyperpolarizability (Y), and third-order nonlinear susceptibility (/m[/(3)]) values are also reported for these dyes. The optical limiting values of one of the BODIPY dyes in solution, and two of the BODIPY-embedded PBC films, were below the maximum threshold of 0.95 J-cm-2. The effect of addition of substituents on the electronic structure of the BODIPY dyes was investigated using TD-DFT calculations. The calculated trends closely followed those determined experimentally.
- Full Text:
- Date Issued: 2018
- Authors: Harris, Jessica
- Date: 2018
- Subjects: Photosensitizing compounds , Active oxygen -- Physiological effect , Photochemotherapy , Cancer -- Treatment , Nonlinear optics , BODIPY (Boron-dipyrromethene)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58002 , vital:27014
- Description: A series of structurally related BODIPY dyes were synthesised and characterised. Their photophysical properties were studied in order to determine whether they would be suitable candidates for use as photosensitisers in the photodynamic therapy (PDT) treatment of cancer. The synthesis of two highly fluorescent BODIPY cores was achieved via the acid-catalysed condensation of a pyrrole and a functionalised aldehyde. In order to promote intersystem crossing, and hence improve the singlet oxygen generation of these dyes, bromine atoms were added at the 2,6-positions of the BODIPY core. These dibrominated analogues showed good singlet oxygen quantum yields, and excellent photostability in ethanol. In order to red-shift the main spectral bands of the BODIPY dyes towards the therapeutic window, vinyl/ styryl groups were introduced at the 3-, 5-, and 7-positions via a modified Knoevengal condensation reaction. The addition of vinyl/ styryl groups to the BODIPY core caused an increase in fluorescence quantum yield as well as a decrease in singlet oxygen quantum yield with respect to the dibrominated analogues. However, two of the red-shifted BODIPY dyes still showed moderate singlet oxygen quantum yields. The use of BODIPY dyes in nonlinear optics (NLO) was explored. The nonlinear optical characterisations and optical limiting properties of a series of 3,5-dithienylenevinylene BODIPY dyes were studied, both in dimethylformamide (DMF) solution and when embedded in poly(bisphenol A carbonate) (PBC) as thin films. The 3,5-dithienylenevinylene BODIPY dyes showed typical nonlinear absorption behaviour, with reverse saturable absorption (RSA) profiles, indicating that they have potential as optical limiters. The second-order hyperpolarizability (Y), and third-order nonlinear susceptibility (/m[/(3)]) values are also reported for these dyes. The optical limiting values of one of the BODIPY dyes in solution, and two of the BODIPY-embedded PBC films, were below the maximum threshold of 0.95 J-cm-2. The effect of addition of substituents on the electronic structure of the BODIPY dyes was investigated using TD-DFT calculations. The calculated trends closely followed those determined experimentally.
- Full Text:
- Date Issued: 2018
Studies in the plant ecology of Fern Kloof near Grahamstown
- Authors: Seagrief, S C
- Date: 1950
- Subjects: Plant communities -- South Africa -- Eastern Cape , Plant ecology -- South Africa -- Eastern Cape , Plants -- South Africa -- Eastern Cape , Forest ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4267 , http://hdl.handle.net/10962/d1014299
- Description: The area studied at Fern Kloof, near Grahamstown, consists of a strip of vegetation approximately 260 yds. long and 50 yds. wide, in which there are two communities: 1) indigenous forest 2) exotic Pine forest (which has only one tree species Pinus pinaster). Throughout the thesis this species is referred to as the pine. The object of the investigation has been to determine whether these communities are natural or not. This has involved a study of the floristic composition, the life forms and the structure of the plant communities. In addition, various soil and environmental factors have been studied.
- Full Text:
- Date Issued: 1950
- Authors: Seagrief, S C
- Date: 1950
- Subjects: Plant communities -- South Africa -- Eastern Cape , Plant ecology -- South Africa -- Eastern Cape , Plants -- South Africa -- Eastern Cape , Forest ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4267 , http://hdl.handle.net/10962/d1014299
- Description: The area studied at Fern Kloof, near Grahamstown, consists of a strip of vegetation approximately 260 yds. long and 50 yds. wide, in which there are two communities: 1) indigenous forest 2) exotic Pine forest (which has only one tree species Pinus pinaster). Throughout the thesis this species is referred to as the pine. The object of the investigation has been to determine whether these communities are natural or not. This has involved a study of the floristic composition, the life forms and the structure of the plant communities. In addition, various soil and environmental factors have been studied.
- Full Text:
- Date Issued: 1950