Development and assessment of a fixed dose combination of perindopril arginine and indapamide loaded microparticles
- Authors: Mandava, Tavonga Tyomai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164413 , vital:41116
- Description: Thesis (MSc)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
- Authors: Mandava, Tavonga Tyomai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164413 , vital:41116
- Description: Thesis (MSc)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
Development of a low-cost bioprinting system for engineering of Human Tumour Models
- Authors: Fanucci, Sidne
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163295 , vital:41026
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biotechnology Innovation Centre, 2020.
- Full Text:
- Authors: Fanucci, Sidne
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163295 , vital:41026
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biotechnology Innovation Centre, 2020.
- Full Text:
Development of a protocol for extracting and quantifying the concentration of thiafentanil in blesbok (Damaliscus pygargus phillipsi) matrices 72-74 hours post administration
- Authors: Webber, Judith Tracy
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164738 , vital:41159
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Chemistry, 2020
- Full Text:
- Authors: Webber, Judith Tracy
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164738 , vital:41159
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Chemistry, 2020
- Full Text:
Development of graphene materials and phthalocyanines for application in dye-sensitized solar cells
- Authors: Chindeka, Francis
- Date: 2020
- Subjects: Dye-sensitized solar cells , Graphene , Phthalocyanines , Molecular orbitals , Impedance spectroscopy
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166092 , vital:41328
- Description: Two sets of dye-sensitized solar cells (DSSCs) were fabricated. In the first set, dye-sensitized solar cells (DSSC) were fabricated by incorporating graphene materials as catalysts at the counter electrode. Platinum was also used as a catalyst for comparative purposes. Different phthalocyanines: hydroxyl indium tetracarboxyphenoxy phthalocyanine (1), chloro indium octacarboxy phthalocyanine (2) and dibenzoic acid silicon phthalocyanine (3) were used as dyes. Complex 3 gave the highest power conversion efficiency (η) of 3.19% when using nitrogen doped reduced graphene oxide nanosheets (NrGONS) as a catalyst at the counter electrode, and TiO2 containing rGONS at the anode. The value obtained is close to 3.8% obtained when using Pt catalyst instead of NrGONS at the cathode, thus confirming that NrGONS is a promising candidate to replace the more expensive Pt. The study also shows that placing rGONS on both the anode and cathode improves efficiency. In the second set, DSSCs were fabricated by using 2(3,5-biscarboxyphenoxy), 9(10), 16(17), 23(24)-tri(tertbutyl) phthalocyaninato Cu (4) and Zn (5) complexes as dyes on the ITO-TiO2 photoanodes containing reduced graphene oxide nanosheets (rGONS) or nitrogen-doped rGONS (NrGONS). The evaluation of the assembled DSSCs revealed that using ITO-TiO2-NrGONS-CuPc (4) photoanode had the highest fill factor (FF) and power conversion efficiency (ɳ) of 69 % and 4.36 % respectively. These results show that the asymmetrical phthalocyanine complexes (4) and (5) showed significant improvement on the performance of the DSSC compared to previous work on symmetrical carboxylated phthalocyanines with ɳ = 3.19%.
- Full Text:
- Authors: Chindeka, Francis
- Date: 2020
- Subjects: Dye-sensitized solar cells , Graphene , Phthalocyanines , Molecular orbitals , Impedance spectroscopy
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166092 , vital:41328
- Description: Two sets of dye-sensitized solar cells (DSSCs) were fabricated. In the first set, dye-sensitized solar cells (DSSC) were fabricated by incorporating graphene materials as catalysts at the counter electrode. Platinum was also used as a catalyst for comparative purposes. Different phthalocyanines: hydroxyl indium tetracarboxyphenoxy phthalocyanine (1), chloro indium octacarboxy phthalocyanine (2) and dibenzoic acid silicon phthalocyanine (3) were used as dyes. Complex 3 gave the highest power conversion efficiency (η) of 3.19% when using nitrogen doped reduced graphene oxide nanosheets (NrGONS) as a catalyst at the counter electrode, and TiO2 containing rGONS at the anode. The value obtained is close to 3.8% obtained when using Pt catalyst instead of NrGONS at the cathode, thus confirming that NrGONS is a promising candidate to replace the more expensive Pt. The study also shows that placing rGONS on both the anode and cathode improves efficiency. In the second set, DSSCs were fabricated by using 2(3,5-biscarboxyphenoxy), 9(10), 16(17), 23(24)-tri(tertbutyl) phthalocyaninato Cu (4) and Zn (5) complexes as dyes on the ITO-TiO2 photoanodes containing reduced graphene oxide nanosheets (rGONS) or nitrogen-doped rGONS (NrGONS). The evaluation of the assembled DSSCs revealed that using ITO-TiO2-NrGONS-CuPc (4) photoanode had the highest fill factor (FF) and power conversion efficiency (ɳ) of 69 % and 4.36 % respectively. These results show that the asymmetrical phthalocyanine complexes (4) and (5) showed significant improvement on the performance of the DSSC compared to previous work on symmetrical carboxylated phthalocyanines with ɳ = 3.19%.
- Full Text:
Development of paper-based aptasensors for detection of Plasmodium falciparum lactate dehydrogenase in malaria
- Ogunmolasuyi, Adewoyin Martin
- Authors: Ogunmolasuyi, Adewoyin Martin
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164601 , vital:41147 , doi:10.21504/10962/164601
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biotechnology Innovation Centre, 2020
- Full Text:
- Authors: Ogunmolasuyi, Adewoyin Martin
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164601 , vital:41147 , doi:10.21504/10962/164601
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biotechnology Innovation Centre, 2020
- Full Text:
Digital media marketing and the consumption of sugar-sweetened beverages in Africa: A reception analysis of the multi-channel marketing of Coca-Cola among young Africans from the University of Lagos, Nigeria and Rhodes University, South Africa
- Authors: Akingbade, Olutobi Elijah
- Date: 2020
- Subjects: Carbonated beverages -- Health aspects -- South Africa , Carbonated beverages -- Marketing -- South Africa , Soft drinks -- Health aspects -- South Africa , Soft drinks -- Marketing -- South Africa , Carbonated beverages -- Health aspects -- Nigeria , Carbonated beverages -- Marketing -- Nigeria , Digital media -- Marketing -- Africa , Soft drinks -- Health aspects -- Nigeria , Soft drinks -- Marketing -- Nigeria , Digital media -- Marketing -- Nigeria , Obesity -- Africa , Nutritionally induced diseases -- Africa , Coca-Cola Company -- Marketing , Rhodes University -- Students -- Attitudes , University of Lagos -- Students -- Attitudes
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/163125 , vital:41012
- Description: This study investigates and examines how Coca-Cola’s marketing communications, especially the newer forms of digital, social and mobile media marketing messages/campaigns, are received, understood and made sense of by two sets of purposefully selected young urban African students in Nigeria and South Africa. Embedded within a qualitative research design and underpinned by an interpretative phenomenological analysis (IPA) approach, this study was conducted against the backdrop of the recent surge in the consumption of Sugar Sweetened Beverages (SSBs) which has been directly implicated in the rise of obesity and a variety of non-communicable diseases (NCDs) in Africa. The thesis explores the role of multinational SSBs in this surge, as African countries have become key focus areas for multinational food and beverage companies seeking growth and profits, as home markets decline partly due to better health communications and, in some cases, the implementation of so-called ‘sugar taxes’ and the attendant negative publicity around these taxes. The focus on young Africans from Nigeria and South Africa was motivated by the similar rapid urbanisations in both countries, often accompanied by changes in diet and greater consumption of fast foods and SSBS, and by South Africa’s ranking as the country with the highest prevalence of overweight persons and obesity in Sub-Saharan Africa. Similar rises in national average weights are now also starting to be seen in Nigeria, as are surges of diet-related disease incidence and prevalence. The study is informed by Consumer Culture Theory (CCT) but also draws on other theories and some key concepts from marketing studies, health science and psychology. Methodologically, the study draws on in-person observations, focus group interviews and semi-structured individual in-depth interviews, to explore how Coca-Cola has created a deep and evocative historical ‘brandscape’ and how it has become a multicultural resource in both South Africa and Nigeria. Through an investigation into the lived experiences of study participants with regards to both their earliest and more recent engagements with Coca-Cola, as a brand and as a product, the study delineates the influence of older generations of Coke enthusiasts and consumers within participants’ households and newer spaces of interaction with Coke via interactive, highly personalised social media-centric campaigns. This study explores how the ubiquitous nature of Coca-Cola’s aesthetics and signage are engaged with – often in very ‘sub-conscious’ ways – by these students and how more recent social media campaigns evoke this multigenerational history. Unpacking study participants’ self-understandings of Coke and their often ‘sub-conscious’ engagements with the SSB, this study explicates the underpinning ideological grounding and how this is sustained over time to become an hegemonic code that does not only confine participants’ engagements with SSBs to Coke but also confines their reception of, and engagements with, Coke’s media marketing messages/campaigns to those that resonate with the multigenerational history evoked by the SSB. It is within this contextual background that this study brings to the fore participants ‘cognitive dissonance’ and scepticism and often rank disbelief of the health risks posed by their high levels of Coke consumption. The study concludes that attempts to raise awareness about the dangers inherent in excessive consumption of SSBs in Africa need to be reviewed and rethought. There is a need for long-term, consistent and much more proactive health journalism, alongside public health campaigns in both official and indigenous languages, to dispel the powerful myths created by SSB marketing and explain how SSBs are implicated in the rise of diet-related NCDs in Nigeria and South Africa.
- Full Text:
- Authors: Akingbade, Olutobi Elijah
- Date: 2020
- Subjects: Carbonated beverages -- Health aspects -- South Africa , Carbonated beverages -- Marketing -- South Africa , Soft drinks -- Health aspects -- South Africa , Soft drinks -- Marketing -- South Africa , Carbonated beverages -- Health aspects -- Nigeria , Carbonated beverages -- Marketing -- Nigeria , Digital media -- Marketing -- Africa , Soft drinks -- Health aspects -- Nigeria , Soft drinks -- Marketing -- Nigeria , Digital media -- Marketing -- Nigeria , Obesity -- Africa , Nutritionally induced diseases -- Africa , Coca-Cola Company -- Marketing , Rhodes University -- Students -- Attitudes , University of Lagos -- Students -- Attitudes
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/163125 , vital:41012
- Description: This study investigates and examines how Coca-Cola’s marketing communications, especially the newer forms of digital, social and mobile media marketing messages/campaigns, are received, understood and made sense of by two sets of purposefully selected young urban African students in Nigeria and South Africa. Embedded within a qualitative research design and underpinned by an interpretative phenomenological analysis (IPA) approach, this study was conducted against the backdrop of the recent surge in the consumption of Sugar Sweetened Beverages (SSBs) which has been directly implicated in the rise of obesity and a variety of non-communicable diseases (NCDs) in Africa. The thesis explores the role of multinational SSBs in this surge, as African countries have become key focus areas for multinational food and beverage companies seeking growth and profits, as home markets decline partly due to better health communications and, in some cases, the implementation of so-called ‘sugar taxes’ and the attendant negative publicity around these taxes. The focus on young Africans from Nigeria and South Africa was motivated by the similar rapid urbanisations in both countries, often accompanied by changes in diet and greater consumption of fast foods and SSBS, and by South Africa’s ranking as the country with the highest prevalence of overweight persons and obesity in Sub-Saharan Africa. Similar rises in national average weights are now also starting to be seen in Nigeria, as are surges of diet-related disease incidence and prevalence. The study is informed by Consumer Culture Theory (CCT) but also draws on other theories and some key concepts from marketing studies, health science and psychology. Methodologically, the study draws on in-person observations, focus group interviews and semi-structured individual in-depth interviews, to explore how Coca-Cola has created a deep and evocative historical ‘brandscape’ and how it has become a multicultural resource in both South Africa and Nigeria. Through an investigation into the lived experiences of study participants with regards to both their earliest and more recent engagements with Coca-Cola, as a brand and as a product, the study delineates the influence of older generations of Coke enthusiasts and consumers within participants’ households and newer spaces of interaction with Coke via interactive, highly personalised social media-centric campaigns. This study explores how the ubiquitous nature of Coca-Cola’s aesthetics and signage are engaged with – often in very ‘sub-conscious’ ways – by these students and how more recent social media campaigns evoke this multigenerational history. Unpacking study participants’ self-understandings of Coke and their often ‘sub-conscious’ engagements with the SSB, this study explicates the underpinning ideological grounding and how this is sustained over time to become an hegemonic code that does not only confine participants’ engagements with SSBs to Coke but also confines their reception of, and engagements with, Coke’s media marketing messages/campaigns to those that resonate with the multigenerational history evoked by the SSB. It is within this contextual background that this study brings to the fore participants ‘cognitive dissonance’ and scepticism and often rank disbelief of the health risks posed by their high levels of Coke consumption. The study concludes that attempts to raise awareness about the dangers inherent in excessive consumption of SSBs in Africa need to be reviewed and rethought. There is a need for long-term, consistent and much more proactive health journalism, alongside public health campaigns in both official and indigenous languages, to dispel the powerful myths created by SSB marketing and explain how SSBs are implicated in the rise of diet-related NCDs in Nigeria and South Africa.
- Full Text:
Disco
- Authors: Trantraal, Nathan
- Date: 2020
- Subjects: Kaaps , South African fiction (English) -- 21st century , South African poetry (English) -- 21st century , Afrikaans fiction -- 21st century , Afrikaans poetry -- 21st century
- Language: Afrikaans , English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/145217 , vital:38419
- Description: Creative writing portfolio.
- Full Text:
- Authors: Trantraal, Nathan
- Date: 2020
- Subjects: Kaaps , South African fiction (English) -- 21st century , South African poetry (English) -- 21st century , Afrikaans fiction -- 21st century , Afrikaans poetry -- 21st century
- Language: Afrikaans , English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/145217 , vital:38419
- Description: Creative writing portfolio.
- Full Text:
Discursive constructions of alcohol use and pregnancy among participants in intervention aimed at reducing Foetal Alcohol Spectrum Disorders
- Authors: Msomi, Nqobile Nomonde
- Date: 2020
- Subjects: Fetal alcohol spectrum disorders -- South Africa , Pregnancy -- Psychological aspects , Reproductive rights -- South Africa , Reproductive health -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/140374 , vital:37883
- Description: South Africa’s socio-cultural and political history has had significant effects on maternal and reproductive health. The hazardous alcohol use patterns in the country have affected alcohol consumption during pregnancy. Antenatal exposure to alcohol may result in Foetal Alcohol Spectrum Disorders (FASD). The levels of FASD in particular areas of the country are the highest recorded in the world. Epidemiological studies have dominated pregnancy and FASD research in South Africa; however, recently critical scholarship seeking to contextualise the issue of drinking alcohol during pregnancy is emerging. This study forms part of a developmental/formative assessment of an alcohol and pregnancy intervention. Assessment is an important part of pilot interventions, and discourse is a key area of focus due to its constitutive role for the subjectivity of human beings and legitimation of institutional practices. Using a reproductive justice perspective and a Foucauldian approach to analysis, I identified five prominent discursive constructions of alcohol use during pregnancy produced during interviews with community educators. These interviews were conducted following training workshops with the community educators. Participants constructed their living environments as ‘wholly bad’ and ‘issue-ridden’ and positioned alcohol consumption as ‘a destroyer!’, ‘king’ and a social lubricant. They interpellated the foetus, the ‘FASD child’ and pregnant women into this context. They positioned themselves as transformed subjects able to effect change. The foetus was constructed as ‘vulnerable and important’, as opposed to the ‘defiled FASD child’. Pregnant women were constructed as ‘ignorant, preoccupied and unreceptive to knowledge’. These constructions hinged on so-called ‘scientific knowledge’ of biological processes in utero, demonstrating Foucault’s conception of the power/knowledge nexus and how its dynamics transforms knowledge of human beings. Whereas this ‘knowledge’ transformed alcohol consumption and the foetus into powerful and vulnerable subjects respectively, the circulating discourses had objectivising effects on pregnant women. The discourses of responsibilisation, the personification of the foetus, ‘the problem’ category of FASD, the discourse of difference, and the discourse of alcohol consumption as an entrenched practice were circulating around pregnant women. I suggest alterations to the identified constructions using principles of community psychology, the harm reduction model, a social model of disability and the reproductive justice perspective
- Full Text:
- Authors: Msomi, Nqobile Nomonde
- Date: 2020
- Subjects: Fetal alcohol spectrum disorders -- South Africa , Pregnancy -- Psychological aspects , Reproductive rights -- South Africa , Reproductive health -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/140374 , vital:37883
- Description: South Africa’s socio-cultural and political history has had significant effects on maternal and reproductive health. The hazardous alcohol use patterns in the country have affected alcohol consumption during pregnancy. Antenatal exposure to alcohol may result in Foetal Alcohol Spectrum Disorders (FASD). The levels of FASD in particular areas of the country are the highest recorded in the world. Epidemiological studies have dominated pregnancy and FASD research in South Africa; however, recently critical scholarship seeking to contextualise the issue of drinking alcohol during pregnancy is emerging. This study forms part of a developmental/formative assessment of an alcohol and pregnancy intervention. Assessment is an important part of pilot interventions, and discourse is a key area of focus due to its constitutive role for the subjectivity of human beings and legitimation of institutional practices. Using a reproductive justice perspective and a Foucauldian approach to analysis, I identified five prominent discursive constructions of alcohol use during pregnancy produced during interviews with community educators. These interviews were conducted following training workshops with the community educators. Participants constructed their living environments as ‘wholly bad’ and ‘issue-ridden’ and positioned alcohol consumption as ‘a destroyer!’, ‘king’ and a social lubricant. They interpellated the foetus, the ‘FASD child’ and pregnant women into this context. They positioned themselves as transformed subjects able to effect change. The foetus was constructed as ‘vulnerable and important’, as opposed to the ‘defiled FASD child’. Pregnant women were constructed as ‘ignorant, preoccupied and unreceptive to knowledge’. These constructions hinged on so-called ‘scientific knowledge’ of biological processes in utero, demonstrating Foucault’s conception of the power/knowledge nexus and how its dynamics transforms knowledge of human beings. Whereas this ‘knowledge’ transformed alcohol consumption and the foetus into powerful and vulnerable subjects respectively, the circulating discourses had objectivising effects on pregnant women. The discourses of responsibilisation, the personification of the foetus, ‘the problem’ category of FASD, the discourse of difference, and the discourse of alcohol consumption as an entrenched practice were circulating around pregnant women. I suggest alterations to the identified constructions using principles of community psychology, the harm reduction model, a social model of disability and the reproductive justice perspective
- Full Text:
Distribution, habitat associations and conservation of the Eastern Cape rocky Sandelia bainsii (Perciform: Anabantidae) in the Great Fish River system
- Authors: Sifundza, Delsy Sindy
- Date: 2020
- Subjects: Anabantidae -- South Africa -- Great Fish River , Perciformes -- South Africa -- Great Fish River , Labyrinth fishes -- South Africa -- Great Fish River , Fishes -- Effect of human beings on -- South Africa -- Great Fish River , Fish populations -- South Africa -- Great Fish River , Fish declines -- South Africa -- Great Fish River , Fish populations -- Monitoring -- South Africa -- Great Fish River , Anabantidae -- Evolution -- South Africa -- Great Fish River , Gene flow , Mitochondrial DNA , Microsatellites (Genetics) , Eastern Cape rocky Sandelia bainsii , Freshwater ecology -- South Africa -- Great Fish River
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/142692 , vital:38102
- Description: In South Africa, freshwater ecosystems are under pressure due to increasing anthropogenic factors degrading river systems. The Cape Fold, the lower Southern Temperate Highveld and the Amatolo – Winterberg Highlands freshwater ecoregions contain some of the heavily impacted river systems in the country. One such river system is the Great Fish River system, which has been affected by anthropogenic modification (hydrological modification, water pollution and invasion by non-native fish species). These modifications have raised conservation concerns on an imperilled anabantid fish, the Eastern Cape rocky Sandelia bainsii that is confined to the Kat and Koonap rivers, which are tributaries of the Great Fish River. Historically, the species was reportedly common and abundant, with a range spanning across seven river systems (Kowie, Great Fish, Keiskamma, Igoda, Gxulu, Buffalo and Nahoon rivers) in the Eastern Cape Province. However, surveys have indicated that the species has experienced decline in population size and distribution range, with localised extirpations being reported. This resulted in its listing on the IUCN Red List of threatened species as Endangered. The proposed shale gas exploration and potential infrastructure development in the Karoo basin, which encompasses the headwaters of the Kat River, represent a potential future threat to the remnant populations of this species. The aim of the present study was to review the past and present distribution range of S. bainsii, determine the habitat associations and assess the conservation of S. bainsii in the Great Fish River system. This information is essential for informing conservation and management decisions for this species in the Great Fish River system. This study undertook a comprehensive survey of the Kat and the Koonap rivers in 2017, and augmented this information with data from more recent surveys that were conducted from 2009 - 2014 to map the distributions freshwater fishes in the Great Fish River system. Data from these recent surveys (2009 – 2017) were compared with historical records (1961 – 2005) obtained from the South African Institute for Aquatic Biodiversity to evaluate changes in distribution patterns of S. bainsii. Historical records indicated that S. bainsii occurred at 11 localities in the Kat River and three localities in the Koonap River. Data from recent surveys indicated that the species has persisted at these historical localities, except one locality in the Koonap River where no individuals of S. bainsii were captured, despite the use of multiple sampling approaches and gears. Although the species still persists at two of the three historical localities in the Koonap River, the population sizes have considerably declined as the species was reportedly in high abundance at these localities in the 1980s. Factors threatening the continued existence of this species in the Koonap River likely include non-native species, extreme drought conditions and the associated excessive abstraction of water which has resulted in the drying of some of the refugia pools where the species was historically common and abundant. In contrast to the Koonap River, the 2017 survey indicated that in the Kat River, S. bainsii had a similar distribution range compared to historical records. The species occurred at 11 of the 41 localities that were sampled in the Kat River, and the sampled populations consisted of all size classes. Sandelia bainsii occurred with other native fish species in the system, including Labeo umbratus, Enteromius anoplus and Glossogobius callidus. A comparison of historical and recent data indicates that non-native fishes have likely not expanded their ranges in the Kat River. This is likely due to the presence of weirs and dams that have prevented upstream movement of non-native fish species L. aeneus, C. gariepinus and T. sparrmanii which are now abundant in the lower Kat and mainstem Great Fish River. Surveys from the present study indicated that although S. bainsii still persists within the Kat River, there are a number of factors that pose a considerable threat to the continued existence of this species in the Great Fish River system. Chapter 3 evaluated the habitat associations of S. bainsii based on 10 physical and chemical variables and distribution data collected from 30 localities in the Upper Kat River and seven of its tributaries. A non-metric multidimensional scaling model was used to assess the distribution patterns of S. bainsii in relation to environmental variables. Furthermore, a negative binomial generalised linear model (GLM) was used to assess the relationship between the abundance of S. bainsii and environmental variables. Results from the present study indicated that S. bainsii was a habitat generalist as the distribution of this species showed no specific association with any of the habitat variables that were considered in this study. The species occurred in a wide range of habitats, including rocky sections in the upper Kat River and its tributaries as well as the mainstem sections. The GLM however indicated that the abundance of S. bainsii was negatively associated with increasing conductivity. In addition, the Kat River contains multiple weirs of variable sizes. Future studies should therefore evaluate the effects of these weirs on population fragmentation, gene flow and long-term evolutionary potential of S. bainsii through the application of techniques such as mitochondrial DNA and microsatellites.
- Full Text:
- Authors: Sifundza, Delsy Sindy
- Date: 2020
- Subjects: Anabantidae -- South Africa -- Great Fish River , Perciformes -- South Africa -- Great Fish River , Labyrinth fishes -- South Africa -- Great Fish River , Fishes -- Effect of human beings on -- South Africa -- Great Fish River , Fish populations -- South Africa -- Great Fish River , Fish declines -- South Africa -- Great Fish River , Fish populations -- Monitoring -- South Africa -- Great Fish River , Anabantidae -- Evolution -- South Africa -- Great Fish River , Gene flow , Mitochondrial DNA , Microsatellites (Genetics) , Eastern Cape rocky Sandelia bainsii , Freshwater ecology -- South Africa -- Great Fish River
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/142692 , vital:38102
- Description: In South Africa, freshwater ecosystems are under pressure due to increasing anthropogenic factors degrading river systems. The Cape Fold, the lower Southern Temperate Highveld and the Amatolo – Winterberg Highlands freshwater ecoregions contain some of the heavily impacted river systems in the country. One such river system is the Great Fish River system, which has been affected by anthropogenic modification (hydrological modification, water pollution and invasion by non-native fish species). These modifications have raised conservation concerns on an imperilled anabantid fish, the Eastern Cape rocky Sandelia bainsii that is confined to the Kat and Koonap rivers, which are tributaries of the Great Fish River. Historically, the species was reportedly common and abundant, with a range spanning across seven river systems (Kowie, Great Fish, Keiskamma, Igoda, Gxulu, Buffalo and Nahoon rivers) in the Eastern Cape Province. However, surveys have indicated that the species has experienced decline in population size and distribution range, with localised extirpations being reported. This resulted in its listing on the IUCN Red List of threatened species as Endangered. The proposed shale gas exploration and potential infrastructure development in the Karoo basin, which encompasses the headwaters of the Kat River, represent a potential future threat to the remnant populations of this species. The aim of the present study was to review the past and present distribution range of S. bainsii, determine the habitat associations and assess the conservation of S. bainsii in the Great Fish River system. This information is essential for informing conservation and management decisions for this species in the Great Fish River system. This study undertook a comprehensive survey of the Kat and the Koonap rivers in 2017, and augmented this information with data from more recent surveys that were conducted from 2009 - 2014 to map the distributions freshwater fishes in the Great Fish River system. Data from these recent surveys (2009 – 2017) were compared with historical records (1961 – 2005) obtained from the South African Institute for Aquatic Biodiversity to evaluate changes in distribution patterns of S. bainsii. Historical records indicated that S. bainsii occurred at 11 localities in the Kat River and three localities in the Koonap River. Data from recent surveys indicated that the species has persisted at these historical localities, except one locality in the Koonap River where no individuals of S. bainsii were captured, despite the use of multiple sampling approaches and gears. Although the species still persists at two of the three historical localities in the Koonap River, the population sizes have considerably declined as the species was reportedly in high abundance at these localities in the 1980s. Factors threatening the continued existence of this species in the Koonap River likely include non-native species, extreme drought conditions and the associated excessive abstraction of water which has resulted in the drying of some of the refugia pools where the species was historically common and abundant. In contrast to the Koonap River, the 2017 survey indicated that in the Kat River, S. bainsii had a similar distribution range compared to historical records. The species occurred at 11 of the 41 localities that were sampled in the Kat River, and the sampled populations consisted of all size classes. Sandelia bainsii occurred with other native fish species in the system, including Labeo umbratus, Enteromius anoplus and Glossogobius callidus. A comparison of historical and recent data indicates that non-native fishes have likely not expanded their ranges in the Kat River. This is likely due to the presence of weirs and dams that have prevented upstream movement of non-native fish species L. aeneus, C. gariepinus and T. sparrmanii which are now abundant in the lower Kat and mainstem Great Fish River. Surveys from the present study indicated that although S. bainsii still persists within the Kat River, there are a number of factors that pose a considerable threat to the continued existence of this species in the Great Fish River system. Chapter 3 evaluated the habitat associations of S. bainsii based on 10 physical and chemical variables and distribution data collected from 30 localities in the Upper Kat River and seven of its tributaries. A non-metric multidimensional scaling model was used to assess the distribution patterns of S. bainsii in relation to environmental variables. Furthermore, a negative binomial generalised linear model (GLM) was used to assess the relationship between the abundance of S. bainsii and environmental variables. Results from the present study indicated that S. bainsii was a habitat generalist as the distribution of this species showed no specific association with any of the habitat variables that were considered in this study. The species occurred in a wide range of habitats, including rocky sections in the upper Kat River and its tributaries as well as the mainstem sections. The GLM however indicated that the abundance of S. bainsii was negatively associated with increasing conductivity. In addition, the Kat River contains multiple weirs of variable sizes. Future studies should therefore evaluate the effects of these weirs on population fragmentation, gene flow and long-term evolutionary potential of S. bainsii through the application of techniques such as mitochondrial DNA and microsatellites.
- Full Text:
Diteng tsa ditlhopha tsa maina a Bantu: ntlhathakanelo e le mo Setswanang : “The semantics of Bandu noun classes: a focus on Setswana
- Authors: Tladi, Oboitshepo
- Date: 2020
- Subjects: Tswana language , Tswana language -- Grammar , Tswana language -- Noun , Noun , Bantu languages , Bantu languages -- Noun , Bantu languages -- Grammar
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/167654 , vital:41500
- Description: The present study investigated the semantic classification of the Setswana noun class system. This enquiry falls under the broad area of the noun classification system in Bantu languages, psycholinguistics and lexicogrpahy. Specifically it explores the basis of noun classification in Setswana making indications that Setswana noun classification is based on a partial semantic classification. Data for the study was drawn from the Setswana Oxford Dictionary. Sixty Setswana nouns, from class 1, 3, 5, and 7, were selected and analysed and then grouped into semantic categories (i.e., PERSON, DEROGATION, TRANSPORATION and so forth). The study adopted Kgukutli’s (1994) semantic classification in performing the dictionary analysis. The rest of the data was drawn from the intuitions of thirty-nine contemporary speakers of Setswana, with the aid of a linguistic test which was fashioned according to Selvik’s (2001) psycholinguistic test. The language test required participants to match the predetermined Setswana definitions with hypothetical Setswana nouns with selected class prefixes attached to them. The results from the empirical study showed that speakers were associating prefixes to certain semantic values, suggesting that each noun class had specific semantic content that was unique to that class. The semantic categories created through the dictionary analysis were then compared to those given by the thirty-nine Setswana speakers, to analyse whether there were any similaritires in the semantic classification of the noun classes. The findings of the dictionary analysis and linguistic test revealed that there were certain semantic characteristics that each class was associated with that seemed to be unique to the class. However, there were various semantic overlaps in the semantic categories associated with the different noun classes, which brings into question whether a semantic classification is viable in the classing of nouns. The study suggests that prior classification of Setswana nouns are not precise enough and that additional semantic categories are needed to offer a more precise classification of nouns in this language.
- Full Text:
- Authors: Tladi, Oboitshepo
- Date: 2020
- Subjects: Tswana language , Tswana language -- Grammar , Tswana language -- Noun , Noun , Bantu languages , Bantu languages -- Noun , Bantu languages -- Grammar
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/167654 , vital:41500
- Description: The present study investigated the semantic classification of the Setswana noun class system. This enquiry falls under the broad area of the noun classification system in Bantu languages, psycholinguistics and lexicogrpahy. Specifically it explores the basis of noun classification in Setswana making indications that Setswana noun classification is based on a partial semantic classification. Data for the study was drawn from the Setswana Oxford Dictionary. Sixty Setswana nouns, from class 1, 3, 5, and 7, were selected and analysed and then grouped into semantic categories (i.e., PERSON, DEROGATION, TRANSPORATION and so forth). The study adopted Kgukutli’s (1994) semantic classification in performing the dictionary analysis. The rest of the data was drawn from the intuitions of thirty-nine contemporary speakers of Setswana, with the aid of a linguistic test which was fashioned according to Selvik’s (2001) psycholinguistic test. The language test required participants to match the predetermined Setswana definitions with hypothetical Setswana nouns with selected class prefixes attached to them. The results from the empirical study showed that speakers were associating prefixes to certain semantic values, suggesting that each noun class had specific semantic content that was unique to that class. The semantic categories created through the dictionary analysis were then compared to those given by the thirty-nine Setswana speakers, to analyse whether there were any similaritires in the semantic classification of the noun classes. The findings of the dictionary analysis and linguistic test revealed that there were certain semantic characteristics that each class was associated with that seemed to be unique to the class. However, there were various semantic overlaps in the semantic categories associated with the different noun classes, which brings into question whether a semantic classification is viable in the classing of nouns. The study suggests that prior classification of Setswana nouns are not precise enough and that additional semantic categories are needed to offer a more precise classification of nouns in this language.
- Full Text:
Do submarine canyons influence the structure and diversity of benthic fish assemblages on the continental shelf edge?
- Nyawo, Mpilonhle Aura June-Rose
- Authors: Nyawo, Mpilonhle Aura June-Rose
- Date: 2020
- Subjects: Submarine valleys , iSimangaliso Wetland Park (South Africa) , Biotic communities -- South Africa -- iSimangaliso Wetland Park , Groundfishes -- South Africa -- iSimangaliso Wetland Park , Marine ecology -- South Africa -- iSimangaliso Wetland Park
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167264 , vital:41462
- Description: Marine ecosystems play an important role in human welfare, such as providing food security and providing social, economic and environmental benefits to an increasing human population. However, due to the deleterious impact of overfishing as well as habitat degradation, pollution and climate change, many marine ecosystems and the substantial biodiversity they support, are under increasing threats. Submarine canyon ecosystems cut into the continental margin in all our oceans and are considered regions of enhanced diversity, abundance and biomass for many marine communities, including fish. In South Africa, the tropical Delagoa Ecoregion is characterised by numerous submarine canyons that are home to coelacanths Latimeria chalumnae, and a variety of commercially important line fish species. However, there is currently a lack of information on the ecological structure and functioning of these canyons, in relation to nearby non-canyon ecosystems. The aim of this thesis was to generate knowledge on the role of submarine canyons in influencing the benthic fish assemblage structure and diversity on the continental shelf and shelf edge within the high-latitude coral reef ecosystems in the tropical Delagoa Ecoregion of South Africa. First, a systematic literature review was conducted to examine the current knowledge on the role of submarine canyons on the benthic fish assemblages occurring on continental margins, as well as outline the trends in canyon research. For the fieldwork component of this thesis, baited remote underwater stereo-video systems were utilised to gather data. The first research chapter, chapter 3, investigated the effect of ecosystem and depth on the diversity and structure of benthic fish assemblages within iSimangaliso Wetland Park in the Delagoa Ecoregion. Data were collected in 2017 from Wright Canyon (canyon ecosystem) and adjacent slope ecosystems around the canyon (non-canyon ecosystem) at depths ranging between 70–240 m. The second research chapter, chapter 4, data were collected in 2018, from 60–100 m depths in three ubmarine canyons (Wright, Diepgat,Levens) and their adjacent habitat within iSimangaliso Wetland Park to investigate the diversity patterns and community structure of benthic fish and cons ider location as a factor. The systematic review showed that canyon research is still very much in its infancy, however more papers are expected to be published in the future. There were clear location associated biases detected, with more than 90% of the canyon research being concentrated in the Mediterranean Sea, while only one study was published from South Africa. Most of the reviewed literature focused on invertebrates, with benthic fish (including cartilaginous fish) being the second most studied taxa. A wide range of methods from both fishery- dependent and fishery-independent categories were used to gather the data of benthic fish from the canyons and adjacent areas. With over 8500 submarine canyons mapped globally, the number of submarine canyon research published and the detected location bias is of great concern. More studies are needed in order to understand the role of submarine canyons on adjacent slope habitats Overall, the results from the research chapters indicated that there were higher a bundances in the canyon ecosystem compared to the non-canyon ecosystem. In contrast, evenness and beta-diversity were higher in the non-canyon ecosystem. Relief, bottom type as well as depth played a major role in explaining the observed abundance and diversity patterns. Both evenness and beta-diversity decreased with increase in depth. The canyon and non-canyon also differed in terms of habitat structure. The canyon ecosystem was characterised by patched reef and reef habitats with high relief whereas the non-canyon ecosystem was characterised by flats and habitats, especially at shallower depths. Additionally, there were clear differences in terms of the fish community structure between the canyon and the non-canyon ecosystem. The heterogeneous and complex habitats of the canyon ecosystem were typified by species such as Epinephelus poecilonotus, Polysteganus coeruleopunctatus and Chrysoblephus puniceus in comparison to the less complex habitats outside the canyons that were preferred by species such as Lagocephalus sceleratus, and Rhinobatos leucospilus. The different locations sampled demonstrated that the canyon effect was not onsistent at all locations, with varying results detected in the different sample locations. This research demonstrates that clea r differences exists between the benthic fish assemblages associated with canyon and non-canyon ecosystems and provides important information on the role of submarine canyons in the iSimangaliso Wetland Park. From this thesis, it is clear that a ‘canyon effect’ exists in the continental shelf and shelf edge. The results suggested that heterogeneity of habitats was the most important environmental factor that differed between the canyon and non-canyon ecosystems and these differences in the habitat were driving the observed patterns. This thesis has provided a reference point, with regards to investigating the role and influence of these canyons on benthic fish assemblages occurring on the continental shelf edge. The information provided by this thesis can ultimately be used in other studies investigating benthic fish assemblages in other submarine canyons within iSimangaliso Wetland Park and the rest of South Africa./
- Full Text:
- Authors: Nyawo, Mpilonhle Aura June-Rose
- Date: 2020
- Subjects: Submarine valleys , iSimangaliso Wetland Park (South Africa) , Biotic communities -- South Africa -- iSimangaliso Wetland Park , Groundfishes -- South Africa -- iSimangaliso Wetland Park , Marine ecology -- South Africa -- iSimangaliso Wetland Park
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167264 , vital:41462
- Description: Marine ecosystems play an important role in human welfare, such as providing food security and providing social, economic and environmental benefits to an increasing human population. However, due to the deleterious impact of overfishing as well as habitat degradation, pollution and climate change, many marine ecosystems and the substantial biodiversity they support, are under increasing threats. Submarine canyon ecosystems cut into the continental margin in all our oceans and are considered regions of enhanced diversity, abundance and biomass for many marine communities, including fish. In South Africa, the tropical Delagoa Ecoregion is characterised by numerous submarine canyons that are home to coelacanths Latimeria chalumnae, and a variety of commercially important line fish species. However, there is currently a lack of information on the ecological structure and functioning of these canyons, in relation to nearby non-canyon ecosystems. The aim of this thesis was to generate knowledge on the role of submarine canyons in influencing the benthic fish assemblage structure and diversity on the continental shelf and shelf edge within the high-latitude coral reef ecosystems in the tropical Delagoa Ecoregion of South Africa. First, a systematic literature review was conducted to examine the current knowledge on the role of submarine canyons on the benthic fish assemblages occurring on continental margins, as well as outline the trends in canyon research. For the fieldwork component of this thesis, baited remote underwater stereo-video systems were utilised to gather data. The first research chapter, chapter 3, investigated the effect of ecosystem and depth on the diversity and structure of benthic fish assemblages within iSimangaliso Wetland Park in the Delagoa Ecoregion. Data were collected in 2017 from Wright Canyon (canyon ecosystem) and adjacent slope ecosystems around the canyon (non-canyon ecosystem) at depths ranging between 70–240 m. The second research chapter, chapter 4, data were collected in 2018, from 60–100 m depths in three ubmarine canyons (Wright, Diepgat,Levens) and their adjacent habitat within iSimangaliso Wetland Park to investigate the diversity patterns and community structure of benthic fish and cons ider location as a factor. The systematic review showed that canyon research is still very much in its infancy, however more papers are expected to be published in the future. There were clear location associated biases detected, with more than 90% of the canyon research being concentrated in the Mediterranean Sea, while only one study was published from South Africa. Most of the reviewed literature focused on invertebrates, with benthic fish (including cartilaginous fish) being the second most studied taxa. A wide range of methods from both fishery- dependent and fishery-independent categories were used to gather the data of benthic fish from the canyons and adjacent areas. With over 8500 submarine canyons mapped globally, the number of submarine canyon research published and the detected location bias is of great concern. More studies are needed in order to understand the role of submarine canyons on adjacent slope habitats Overall, the results from the research chapters indicated that there were higher a bundances in the canyon ecosystem compared to the non-canyon ecosystem. In contrast, evenness and beta-diversity were higher in the non-canyon ecosystem. Relief, bottom type as well as depth played a major role in explaining the observed abundance and diversity patterns. Both evenness and beta-diversity decreased with increase in depth. The canyon and non-canyon also differed in terms of habitat structure. The canyon ecosystem was characterised by patched reef and reef habitats with high relief whereas the non-canyon ecosystem was characterised by flats and habitats, especially at shallower depths. Additionally, there were clear differences in terms of the fish community structure between the canyon and the non-canyon ecosystem. The heterogeneous and complex habitats of the canyon ecosystem were typified by species such as Epinephelus poecilonotus, Polysteganus coeruleopunctatus and Chrysoblephus puniceus in comparison to the less complex habitats outside the canyons that were preferred by species such as Lagocephalus sceleratus, and Rhinobatos leucospilus. The different locations sampled demonstrated that the canyon effect was not onsistent at all locations, with varying results detected in the different sample locations. This research demonstrates that clea r differences exists between the benthic fish assemblages associated with canyon and non-canyon ecosystems and provides important information on the role of submarine canyons in the iSimangaliso Wetland Park. From this thesis, it is clear that a ‘canyon effect’ exists in the continental shelf and shelf edge. The results suggested that heterogeneity of habitats was the most important environmental factor that differed between the canyon and non-canyon ecosystems and these differences in the habitat were driving the observed patterns. This thesis has provided a reference point, with regards to investigating the role and influence of these canyons on benthic fish assemblages occurring on the continental shelf edge. The information provided by this thesis can ultimately be used in other studies investigating benthic fish assemblages in other submarine canyons within iSimangaliso Wetland Park and the rest of South Africa./
- Full Text:
Does the construction of ‘rapeable’ bodies constitute an instance of hermeneutical injustice?
- Authors: Weiffenbach, Michaela
- Date: 2020
- Subjects: Zuma, Jacob -- Trials, litigation, etc. , Rape -- Philosophy , Women's rights -- Africa , Women, Black -- Social conditions -- Africa , Masculinity -- Africa , Men, Black -- Africa -- Psychology , Justice (Philosophy)
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/145708 , vital:38460
- Description: This thesis argues that within the conventional imagination of the West, identity functions in a way that particular forms of embodiment are characterised by the experience of endured sexual vulnerability, which I argue is best understood as the construction of ‘rapeable’ bodies (Cahill 2001, 120). By this, I mean that the threat of rape is contingent upon the social and political construction of one’s identity as vulnerable. In virtue of this particular way of constructing the embodiment of certain subjectivities, there is an instance of hermeneutical injustice conferred (Fricker 2007, 114). I inquire into the function and meaning of stereotypic generalisations, prejudice and rape myths embedded within the dominant framework of the West and show how language and representation constructs these identities as ‘rapeable’. Furthermore, I consider how collective hermeneutical discourses construct Blackness, specifically Black masculinities and the construction of the ‘un-rapeable’ Black femxle body. To see how these ideas are congruous the prominent example that occurred in South Africa in 2005, namely, the Jacob Zuma rape trial comes to mind. One relevant feature of the case is that it shows how identities of race are constructed in the aftermath of apartheid and points to a Western collective imagination resistant to change. In addition, it demonstrates the triad of interrelatedness holding between the self-world-other, a relationship constituted mutually by the self and the socially constructed interpretations of identity and embodiment (du Toit 2009, 58). Lastly, the construction of ‘rapeable’ bodies is an example of how discursive narratives construct particular identities as vulnerable through rendering particular embodied subjects as sexually irrelevant and hermeneutically obscured.
- Full Text:
- Authors: Weiffenbach, Michaela
- Date: 2020
- Subjects: Zuma, Jacob -- Trials, litigation, etc. , Rape -- Philosophy , Women's rights -- Africa , Women, Black -- Social conditions -- Africa , Masculinity -- Africa , Men, Black -- Africa -- Psychology , Justice (Philosophy)
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/145708 , vital:38460
- Description: This thesis argues that within the conventional imagination of the West, identity functions in a way that particular forms of embodiment are characterised by the experience of endured sexual vulnerability, which I argue is best understood as the construction of ‘rapeable’ bodies (Cahill 2001, 120). By this, I mean that the threat of rape is contingent upon the social and political construction of one’s identity as vulnerable. In virtue of this particular way of constructing the embodiment of certain subjectivities, there is an instance of hermeneutical injustice conferred (Fricker 2007, 114). I inquire into the function and meaning of stereotypic generalisations, prejudice and rape myths embedded within the dominant framework of the West and show how language and representation constructs these identities as ‘rapeable’. Furthermore, I consider how collective hermeneutical discourses construct Blackness, specifically Black masculinities and the construction of the ‘un-rapeable’ Black femxle body. To see how these ideas are congruous the prominent example that occurred in South Africa in 2005, namely, the Jacob Zuma rape trial comes to mind. One relevant feature of the case is that it shows how identities of race are constructed in the aftermath of apartheid and points to a Western collective imagination resistant to change. In addition, it demonstrates the triad of interrelatedness holding between the self-world-other, a relationship constituted mutually by the self and the socially constructed interpretations of identity and embodiment (du Toit 2009, 58). Lastly, the construction of ‘rapeable’ bodies is an example of how discursive narratives construct particular identities as vulnerable through rendering particular embodied subjects as sexually irrelevant and hermeneutically obscured.
- Full Text:
Dynamics of stimulated luminescence in natural quartz: Thermoluminescence and phototransferred thermoluminescence
- Authors: Folley, Damilola Esther
- Date: 2020
- Subjects: Thermoluminescence , Quartz
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146255 , vital:38509
- Description: Natural quartz has remained an important mineral that is of topical interest in luminescence and dosimetry-related research. We investigate the dynamics of stimulated luminescence on this material through thermoluminescence (TL) and phototransferred thermoluminescence (PTTL). Measurements were made on unannealed natural quartz as well as quartz annealed at 800 and 1000̊C. The samples were annealed for 10 minutes and for 1 hour. The material, in its un- and annealed state has its main peak between 68 and 72̊C when measured at 1Cs ̃1 after a dose of 50 Gy. A study of dosimetric features and kinetic analysis was carried out on two prominent peaks, peak I and III for all the samples. The peaks show a sublinear dose response for irradiation doses between 10 and 300 Gy. Kinetic analysis shows that peak I is a first-order peak and peak III a general-order peak. Interestingly, we observe for peak I for the sample annealed at 800̊C for 1 hour an inverse thermal quenching behaviour. We demonstrate that a peak affected with an inverse thermal quenching-like behaviour can still show effect of thermal quenching when the dose the sample is irradiated to is significantly reduced. We ascribe the apparent dependence of thermal quenching on dose to competition between radiative and non-radiative transitions at the recombination centre. Peaks I, II, and III for all the samples were reproduced under phototransfer when the peaks, initially removed by preheating to a certain temperature are exposed to 470 and 525 nm light. The infuence of duration of illumination on the PTTL intensity of these peaks corresponding to various preheating temperatures is modelled using coupled first-order dfferential equations. The model is based on systems of acceptors and donors whose number and role depends on preheating temperature
- Full Text:
- Authors: Folley, Damilola Esther
- Date: 2020
- Subjects: Thermoluminescence , Quartz
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146255 , vital:38509
- Description: Natural quartz has remained an important mineral that is of topical interest in luminescence and dosimetry-related research. We investigate the dynamics of stimulated luminescence on this material through thermoluminescence (TL) and phototransferred thermoluminescence (PTTL). Measurements were made on unannealed natural quartz as well as quartz annealed at 800 and 1000̊C. The samples were annealed for 10 minutes and for 1 hour. The material, in its un- and annealed state has its main peak between 68 and 72̊C when measured at 1Cs ̃1 after a dose of 50 Gy. A study of dosimetric features and kinetic analysis was carried out on two prominent peaks, peak I and III for all the samples. The peaks show a sublinear dose response for irradiation doses between 10 and 300 Gy. Kinetic analysis shows that peak I is a first-order peak and peak III a general-order peak. Interestingly, we observe for peak I for the sample annealed at 800̊C for 1 hour an inverse thermal quenching behaviour. We demonstrate that a peak affected with an inverse thermal quenching-like behaviour can still show effect of thermal quenching when the dose the sample is irradiated to is significantly reduced. We ascribe the apparent dependence of thermal quenching on dose to competition between radiative and non-radiative transitions at the recombination centre. Peaks I, II, and III for all the samples were reproduced under phototransfer when the peaks, initially removed by preheating to a certain temperature are exposed to 470 and 525 nm light. The infuence of duration of illumination on the PTTL intensity of these peaks corresponding to various preheating temperatures is modelled using coupled first-order dfferential equations. The model is based on systems of acceptors and donors whose number and role depends on preheating temperature
- Full Text:
Ecological assessment of a temperate river system using biomonitoring techniques: a case study of the Bloukrans River system, South Africa
- Authors: Magadze, Tinotenda
- Date: 2020
- Subjects: Bloukrans River , Ecological assessment (Biology) -- South Africa , Stream ecology -- South Africa , Rivers -- Environmental aspects -- South Africa , Benthic animals -- Effect of human beings on -- South Africa , Water quality biological assessment -- South Africa , Diatoms -- South Africa -- Data processing
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/142933 , vital:38177
- Description: Escalating pressures from growing human populations and environmental impacts increasingly imperil freshwater ecosystems. The Bloukrans River, which drains an urbanised and agricultural catchment in the Eastern Cape province of South Africa, is no exception. Detailed knowledge of the structure and function of the aquatic ecosystems is required in order to create models and matrices that predict, guide assessment and direct intervention on ecological integrity and water quality management in these systems. The main objectives of this research were to: examine the effects of urbanization on the benthic macroinvertebrate functional feeding guild structure among different stream orders; determine if benthic diatoms can be used as effective and reliable indicators of ionic composition and conductivity in different stream order categories and finally; to evaluate the applicability of the South African Diatom Index (SADI) and other indices in the Eastern Cape region of South Africa. Field studies were carried out to explore temporal patterns in community structure (macroinvertebrates and diatoms) and ecosystem function related to land-use patterns, instream habitat availability, and water quality parameters in the Bloukrans River system across four study periods: February (summer) and July (winter) 2016 and February (summer) and May/July (winter) 2018. The study was conducted along a gradient of impacts from less impacted agricultural headwaters to highly impacted urban sites located immediately downstream of the city of Makhanda. Macroinvertebrates were separated into functional feeding groups (FFGs) (i.e. collector-gatherer, collector-filterer, scraper, shredder, and predator) which were then used to assess the effects of selected physico-chemical variables and riparian zone condition on FFG organization. Collector-gatherers were the most abundant in the Bloukrans River and represented 71.3 % of the macroinvertebrate assemblages. Stream order 1species such as Nitzschia palea, Gomphonema parvulum, Tryblionella apiculata, Diploneis vulgaris and Staurosira elliptica. Multivariate analysis (Canonical correspondence analysis (CCA)) indicated that differences in diatom community assemblages were best explained by calcium, magnesium, pH, phosphate, nitrate, dissolved oxygen, sediment nitrate, conductivity and salinity. These results indicate that diatoms can be used as bioindicators for monitoring highly impacted river systems and to also further examine pollution gradients and impacts of specific/point pollution sources. In order to further test the application of diatom indices, nine sites with contrasting water quality were sampled along the length river system in February, May and July 2018. Diatom-based indices incorporated in OMNIDIA software were applied to assess the integrity of the water quality as indicated by diatom communities. For comparative purposes, several foreign indices (e.g. the trophic diatom index (TDI), the percentage pollution-tolerant valves (%PTV), biological diatom index (BDI)) and the South African Diatom Index (SADI) were used in the study. From the results, the Percentage Pollution-Tolerant Valves (%PTV) of most urban sites in the Bloukrans River was above the 20% limit indicating the presence of organic pollutants. Although the foreign diatom indices were applicable in the study, the SADI had significant correlations with most water quality variables (p < 0.05) compared to other indices such as Watanabe Index (WAT), Biological Index of Water Quality Trophic Index (BIWQ) and Trophic Index (TI)). These results support wider use of the SADI as an indicator of water quality conditions in South African river systems. Finally, the observed variations in diatom community structure and composition as a result of changes in water quality were broadly in agreement with the results of macroinvertebrate FFG structure indicating that the two biological indicators can, and should, be used as complementary techniques in the biomonitoring of rivers and streams in South Africa.
- Full Text:
- Authors: Magadze, Tinotenda
- Date: 2020
- Subjects: Bloukrans River , Ecological assessment (Biology) -- South Africa , Stream ecology -- South Africa , Rivers -- Environmental aspects -- South Africa , Benthic animals -- Effect of human beings on -- South Africa , Water quality biological assessment -- South Africa , Diatoms -- South Africa -- Data processing
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/142933 , vital:38177
- Description: Escalating pressures from growing human populations and environmental impacts increasingly imperil freshwater ecosystems. The Bloukrans River, which drains an urbanised and agricultural catchment in the Eastern Cape province of South Africa, is no exception. Detailed knowledge of the structure and function of the aquatic ecosystems is required in order to create models and matrices that predict, guide assessment and direct intervention on ecological integrity and water quality management in these systems. The main objectives of this research were to: examine the effects of urbanization on the benthic macroinvertebrate functional feeding guild structure among different stream orders; determine if benthic diatoms can be used as effective and reliable indicators of ionic composition and conductivity in different stream order categories and finally; to evaluate the applicability of the South African Diatom Index (SADI) and other indices in the Eastern Cape region of South Africa. Field studies were carried out to explore temporal patterns in community structure (macroinvertebrates and diatoms) and ecosystem function related to land-use patterns, instream habitat availability, and water quality parameters in the Bloukrans River system across four study periods: February (summer) and July (winter) 2016 and February (summer) and May/July (winter) 2018. The study was conducted along a gradient of impacts from less impacted agricultural headwaters to highly impacted urban sites located immediately downstream of the city of Makhanda. Macroinvertebrates were separated into functional feeding groups (FFGs) (i.e. collector-gatherer, collector-filterer, scraper, shredder, and predator) which were then used to assess the effects of selected physico-chemical variables and riparian zone condition on FFG organization. Collector-gatherers were the most abundant in the Bloukrans River and represented 71.3 % of the macroinvertebrate assemblages. Stream order 1species such as Nitzschia palea, Gomphonema parvulum, Tryblionella apiculata, Diploneis vulgaris and Staurosira elliptica. Multivariate analysis (Canonical correspondence analysis (CCA)) indicated that differences in diatom community assemblages were best explained by calcium, magnesium, pH, phosphate, nitrate, dissolved oxygen, sediment nitrate, conductivity and salinity. These results indicate that diatoms can be used as bioindicators for monitoring highly impacted river systems and to also further examine pollution gradients and impacts of specific/point pollution sources. In order to further test the application of diatom indices, nine sites with contrasting water quality were sampled along the length river system in February, May and July 2018. Diatom-based indices incorporated in OMNIDIA software were applied to assess the integrity of the water quality as indicated by diatom communities. For comparative purposes, several foreign indices (e.g. the trophic diatom index (TDI), the percentage pollution-tolerant valves (%PTV), biological diatom index (BDI)) and the South African Diatom Index (SADI) were used in the study. From the results, the Percentage Pollution-Tolerant Valves (%PTV) of most urban sites in the Bloukrans River was above the 20% limit indicating the presence of organic pollutants. Although the foreign diatom indices were applicable in the study, the SADI had significant correlations with most water quality variables (p < 0.05) compared to other indices such as Watanabe Index (WAT), Biological Index of Water Quality Trophic Index (BIWQ) and Trophic Index (TI)). These results support wider use of the SADI as an indicator of water quality conditions in South African river systems. Finally, the observed variations in diatom community structure and composition as a result of changes in water quality were broadly in agreement with the results of macroinvertebrate FFG structure indicating that the two biological indicators can, and should, be used as complementary techniques in the biomonitoring of rivers and streams in South Africa.
- Full Text:
Ecological engineering: an assessment of the ecological impact of Reno mattress structures used in erosion control in the Keurbooms Estuary, South Africa
- Authors: De Villiers, Nina
- Date: 2020
- Subjects: Sediments (Geology) -- Management , Sediments (Geology) -- South Africa -- Keurboomstrand , Coast changes -- South Africa -- Keurboomstrand , Shore protection -- South Africa -- Keurboomstrand , Coastal engineering-- South Africa -- Keurboomstrand , Coastal zone management-- South Africa -- Keurboomstrand , Estuarine ecology-- South Africa -- Keurboomstrand , Eelgrass -- South Africa -- Keurboomstrand , Reno Mattresses
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166138 , vital:41332
- Description: Global climate changes have been associated with ocean warming and sea-level rise. Armouring of coastlines has become common practice with the increasing threat of coastal erosion. The transformation of soft sediment habitats to hard, artificial habitats because of coastline armouring can lead to changes in species diversity, composition and distribution. It is, therefore, essential to assess changes to habitats from coastal development as well as the ecological impact erosion control structures have within coastal systems. Ecological engineering attempts to combine engineering principals and ecological processes to reduce environmental impacts from coastal development and the implementation of artificial structures. Estuaries are particularly vulnerable to anthropogenic impacts through development, and are extremely important systems offering nursery and foraging grounds for many species. These systems are, however, particularly vulnerable to anthropogenic impacts from urbanisation and development. Within South Africa many estuaries are being transformed by the addition of artificial structures to combat erosion, one such structure is the Reno mattress (a flattened wire box filled with rocks). This study compared the fish diversity and abundances of existing Reno mattress structures and natural eelgrass (Zostera capensis) habitat in the Keurbooms Estuary, South Africa. Benthic invertebrates were sampled using standard core sampling and an adapted suction sampling approach within the two habitats. The non-destructive method of mini Baited Remote Underwater Video Systems (BRUVs) was used to sample fish. Seasonal benthic invertebrate and fish abundances and assemblages were assessed from winter 2018 to spring 2019 with greater abundances of both recorded in summer. Significantly greater abundances, diversity, and richness of fish were found in the Reno mattress habitat compared to Z. capensis. Invertebrate taxa displayed some overlap between habitats, however, three higher taxonomic groups were only recorded within Reno mattress habitat and one only within the eelgrass habitat. Fish assemblages differed significantly between the two established habitats. A Before-After-Control-Impact (BACI) investigation was used to assess the ecological impact of newly installed Reno mattresses in the Keurbooms Estuary. Zostera capensis extent was sampled by determining the percentage cover of 0.5 m X 0.5 m quadrats and measurements of eelgrass blades. Percentage cover and blade length decreased during the installation of Reno mattress, but then recovered shortly after completion of the installation. Abundances, richness and diversity of invertebrates and fish were found to be similar before and after the installation which suggests that the installation had no net negative impact on the site. The Reno mattresses were found to attract fauna typical of rocky shore environments as well as a few invasive alien invertebrate species. This study noted that a hybrid habitat of Reno mattress and eelgrass was created and may in fact provide the positives of both to a system. In any coastal development it will be important to balance the demands of a growing population and the protection of natural habitats. The results of this study suggest that complex artificial structures such as Reno mattresses do provide habitat for fish and invertebrates. However, the use of these structures should be in combination with natural vegetation (e.g. as a hybrid habitat) and not one that replaces intertidal and subtidal natural habitat especially eelgrass. There is limited information regarding the ecological impacts of using Reno mattresses in estuaries and this study provides new information on their ecological efficacy that should be valuable for future coastal erosion control practices.
- Full Text:
- Authors: De Villiers, Nina
- Date: 2020
- Subjects: Sediments (Geology) -- Management , Sediments (Geology) -- South Africa -- Keurboomstrand , Coast changes -- South Africa -- Keurboomstrand , Shore protection -- South Africa -- Keurboomstrand , Coastal engineering-- South Africa -- Keurboomstrand , Coastal zone management-- South Africa -- Keurboomstrand , Estuarine ecology-- South Africa -- Keurboomstrand , Eelgrass -- South Africa -- Keurboomstrand , Reno Mattresses
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166138 , vital:41332
- Description: Global climate changes have been associated with ocean warming and sea-level rise. Armouring of coastlines has become common practice with the increasing threat of coastal erosion. The transformation of soft sediment habitats to hard, artificial habitats because of coastline armouring can lead to changes in species diversity, composition and distribution. It is, therefore, essential to assess changes to habitats from coastal development as well as the ecological impact erosion control structures have within coastal systems. Ecological engineering attempts to combine engineering principals and ecological processes to reduce environmental impacts from coastal development and the implementation of artificial structures. Estuaries are particularly vulnerable to anthropogenic impacts through development, and are extremely important systems offering nursery and foraging grounds for many species. These systems are, however, particularly vulnerable to anthropogenic impacts from urbanisation and development. Within South Africa many estuaries are being transformed by the addition of artificial structures to combat erosion, one such structure is the Reno mattress (a flattened wire box filled with rocks). This study compared the fish diversity and abundances of existing Reno mattress structures and natural eelgrass (Zostera capensis) habitat in the Keurbooms Estuary, South Africa. Benthic invertebrates were sampled using standard core sampling and an adapted suction sampling approach within the two habitats. The non-destructive method of mini Baited Remote Underwater Video Systems (BRUVs) was used to sample fish. Seasonal benthic invertebrate and fish abundances and assemblages were assessed from winter 2018 to spring 2019 with greater abundances of both recorded in summer. Significantly greater abundances, diversity, and richness of fish were found in the Reno mattress habitat compared to Z. capensis. Invertebrate taxa displayed some overlap between habitats, however, three higher taxonomic groups were only recorded within Reno mattress habitat and one only within the eelgrass habitat. Fish assemblages differed significantly between the two established habitats. A Before-After-Control-Impact (BACI) investigation was used to assess the ecological impact of newly installed Reno mattresses in the Keurbooms Estuary. Zostera capensis extent was sampled by determining the percentage cover of 0.5 m X 0.5 m quadrats and measurements of eelgrass blades. Percentage cover and blade length decreased during the installation of Reno mattress, but then recovered shortly after completion of the installation. Abundances, richness and diversity of invertebrates and fish were found to be similar before and after the installation which suggests that the installation had no net negative impact on the site. The Reno mattresses were found to attract fauna typical of rocky shore environments as well as a few invasive alien invertebrate species. This study noted that a hybrid habitat of Reno mattress and eelgrass was created and may in fact provide the positives of both to a system. In any coastal development it will be important to balance the demands of a growing population and the protection of natural habitats. The results of this study suggest that complex artificial structures such as Reno mattresses do provide habitat for fish and invertebrates. However, the use of these structures should be in combination with natural vegetation (e.g. as a hybrid habitat) and not one that replaces intertidal and subtidal natural habitat especially eelgrass. There is limited information regarding the ecological impacts of using Reno mattresses in estuaries and this study provides new information on their ecological efficacy that should be valuable for future coastal erosion control practices.
- Full Text:
Economic evaluation of chemical and biological control methods on four aquatic weeds in South Africa
- Authors: Maluleke, Mary
- Date: 2020
- Subjects: Invasive plants -- Biological control -- Economic aspects -- South Africa , Introduced organisms -- Biological control -- Economic aspects -- South Africa , Aquatic weeds -- Biological control -- Economic aspects -- South Africa , Aquatic weeds -- Control -- Economic aspects -- South Africa , Aquatic resources -- Management , Cost effectiveness , Net present value , Herbicides -- Cost effectiveness , Working for Water Programme , Water conservation -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/145953 , vital:38481
- Description: Invasive alien plants (IAPs) of various kinds pose a threat to ecosystems, biodiversity, conservation and overall economy. In a world experiencing exponential increase in IAPs – this issue has become endemic, especially for developing countries such as South Africa. South Africa is a water scarce country and IAPs increase water stress. Thus, South Africa must invest in a more realistic, environmentally and economically inclusive policy outlook on the management of IAPs including aquatic weeds. This is especially urgent when considering the changing global climate, which is predicted to further reduce the quantity and quality of potable water. The Working for Water Programme (WfW) in South Africa aimed at addressing the issue of IAPs in a way that protects the environment as well as produces maximum return to society through poverty alleviation. As such, the aquatic weeds management strategy put in place for four of South Africa’s aquatic weeds Pista stratiotes, Salvinia molesta, Azolla filiculoides and Myriophyllum aquaticum - should be one that is cost-effective, efficient and sustainable; yielding the best possible return on investment. Since these four weeds are already under complete biological control, in the absence of biological agents, the WfW programme would have used herbicides to control these weeds. As such, this thesis conducted a retrospective analysis of the relative herbicide cost-saving associated with the use of biological control. To do this, due to existing limitations, E. crassipes was used as a surrogate weed and its herbicide control costs were used as proxy for the herbicide control cost estimates of the four selected weeds; with reasonable conversion factors applied to cater for the biological difference of the five weeds. Using the cost benefit analysis (CBA) framework, the net present cost (NPC) of each control method was calculated to which the relative cost-saving was considered to represent the avoided cost of using biological control instead of chemical control on these weeds. The avoided cost was used as the main benefit component when deriving the relative benefit cost ratios (BCR). Two scenarios were used, one assuming no follow-up requirement and the other assuming one follow-up requirement for chemical control. Using an 8% discount rate, the study found that the estimated cost of the biological control method on all four aquatic weeds was about R7,843,205 while for chemical control the estimated costs would have costed R149,580,142, R268,264,838 and R881,711,738 for application by means of a boat, bakkie and knapsack. Chemical control cost estimates would have increased to about R164,538,052, R295,216,120 and R1,008,761,000 for boat, bakkie and knapsack approach respectively when including a possible follow-up programme. These would have led to positive BCRs of 90.24:1, 164.97:1 and 557.99:1 across the three chemical control approaches without a follow-up (with BCR of about 99.67:1, 182.00:1 and 631.56:1 for the boat, bakkie and knapsack approach respectively with the accepted follow-up programme). When running a sensitivity test with varying discount rates of 5% and 10%, these results remained robust. As such, failing to reject the dominant hypothesis in literature, the main conclusion of the study is that biological control is indeed the more cost-effective management option compared to chemical control with respect to herbicide cost-saving. Further, biological control is most-likely to produce more environmental cost-saving and water-saving over chemical control. The study recommends the continued use of the biological control investment on the four aquatic weeds under study as well as on emerging aquatic weeds such as Iris pseudacorus, Nymphaea mexicana and Sagittaria platyphylla in South Africa.
- Full Text:
Economic evaluation of chemical and biological control methods on four aquatic weeds in South Africa
- Authors: Maluleke, Mary
- Date: 2020
- Subjects: Invasive plants -- Biological control -- Economic aspects -- South Africa , Introduced organisms -- Biological control -- Economic aspects -- South Africa , Aquatic weeds -- Biological control -- Economic aspects -- South Africa , Aquatic weeds -- Control -- Economic aspects -- South Africa , Aquatic resources -- Management , Cost effectiveness , Net present value , Herbicides -- Cost effectiveness , Working for Water Programme , Water conservation -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/145953 , vital:38481
- Description: Invasive alien plants (IAPs) of various kinds pose a threat to ecosystems, biodiversity, conservation and overall economy. In a world experiencing exponential increase in IAPs – this issue has become endemic, especially for developing countries such as South Africa. South Africa is a water scarce country and IAPs increase water stress. Thus, South Africa must invest in a more realistic, environmentally and economically inclusive policy outlook on the management of IAPs including aquatic weeds. This is especially urgent when considering the changing global climate, which is predicted to further reduce the quantity and quality of potable water. The Working for Water Programme (WfW) in South Africa aimed at addressing the issue of IAPs in a way that protects the environment as well as produces maximum return to society through poverty alleviation. As such, the aquatic weeds management strategy put in place for four of South Africa’s aquatic weeds Pista stratiotes, Salvinia molesta, Azolla filiculoides and Myriophyllum aquaticum - should be one that is cost-effective, efficient and sustainable; yielding the best possible return on investment. Since these four weeds are already under complete biological control, in the absence of biological agents, the WfW programme would have used herbicides to control these weeds. As such, this thesis conducted a retrospective analysis of the relative herbicide cost-saving associated with the use of biological control. To do this, due to existing limitations, E. crassipes was used as a surrogate weed and its herbicide control costs were used as proxy for the herbicide control cost estimates of the four selected weeds; with reasonable conversion factors applied to cater for the biological difference of the five weeds. Using the cost benefit analysis (CBA) framework, the net present cost (NPC) of each control method was calculated to which the relative cost-saving was considered to represent the avoided cost of using biological control instead of chemical control on these weeds. The avoided cost was used as the main benefit component when deriving the relative benefit cost ratios (BCR). Two scenarios were used, one assuming no follow-up requirement and the other assuming one follow-up requirement for chemical control. Using an 8% discount rate, the study found that the estimated cost of the biological control method on all four aquatic weeds was about R7,843,205 while for chemical control the estimated costs would have costed R149,580,142, R268,264,838 and R881,711,738 for application by means of a boat, bakkie and knapsack. Chemical control cost estimates would have increased to about R164,538,052, R295,216,120 and R1,008,761,000 for boat, bakkie and knapsack approach respectively when including a possible follow-up programme. These would have led to positive BCRs of 90.24:1, 164.97:1 and 557.99:1 across the three chemical control approaches without a follow-up (with BCR of about 99.67:1, 182.00:1 and 631.56:1 for the boat, bakkie and knapsack approach respectively with the accepted follow-up programme). When running a sensitivity test with varying discount rates of 5% and 10%, these results remained robust. As such, failing to reject the dominant hypothesis in literature, the main conclusion of the study is that biological control is indeed the more cost-effective management option compared to chemical control with respect to herbicide cost-saving. Further, biological control is most-likely to produce more environmental cost-saving and water-saving over chemical control. The study recommends the continued use of the biological control investment on the four aquatic weeds under study as well as on emerging aquatic weeds such as Iris pseudacorus, Nymphaea mexicana and Sagittaria platyphylla in South Africa.
- Full Text:
Effect of the nature of nanoparticles on the photophysicochemical properties and photodynamic antimicrobial chemotherapy of phthalocyanines
- Authors: Magadla, Aviwe
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Anti-infective agents -- Therapeutic use , Photochemotherapy , Photochemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/123107 , vital:35406
- Description: In this work, the syntheses and characterisation of Zn monocaffeic acid tri–tert–butyl phthalocyanine (1), Zn monocarboxyphenoxy tri– tert–butylphenoxyl phthalocyanine (2), tetrakis phenoxy N,N-dimethyl-4-(methylimino) phthalocyanine indium (III) chloride (3) and tetrakis N,N-dimethyl-4-(methylimino) phthalocyanine indium (III) chloride (5) are presented. Complexes 3 and 5 were further quartenised with 1,3- propanesultone to form corresponding complexes (4) and (6), respectively. Complexes 1 and 2 were covalently linked to amino functionalised nanoparticles (NPs). Complexes 3, 4, 5 and 6 where linked to oleic acid/oleylamine capped (OLA/OLM) silver-iron dimers (Ag-Fe3O4 OLA/OLM) and silver-iron core shell (Ag@Fe3O4 OLA/OLM) NPs via interaction between the nanoparticles and the imino group on the phthalocyanines. The phthalocyanine-NP conjugates afforded an increase in triplet quantum yields with a corresponding decrease in fluorescence quantum yield as compared to the phthalocyanine complexes alone. Complexes 3, 4 and their conjugates were then used for photodynamic antimicrobial chemotherapy on E. coli. The zwitterionic photosensitiser 4 and its conjugates showed better efficiency for photodynamic antimicrobial chemotherapy compared to their neutral counterparts.
- Full Text:
- Authors: Magadla, Aviwe
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Anti-infective agents -- Therapeutic use , Photochemotherapy , Photochemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/123107 , vital:35406
- Description: In this work, the syntheses and characterisation of Zn monocaffeic acid tri–tert–butyl phthalocyanine (1), Zn monocarboxyphenoxy tri– tert–butylphenoxyl phthalocyanine (2), tetrakis phenoxy N,N-dimethyl-4-(methylimino) phthalocyanine indium (III) chloride (3) and tetrakis N,N-dimethyl-4-(methylimino) phthalocyanine indium (III) chloride (5) are presented. Complexes 3 and 5 were further quartenised with 1,3- propanesultone to form corresponding complexes (4) and (6), respectively. Complexes 1 and 2 were covalently linked to amino functionalised nanoparticles (NPs). Complexes 3, 4, 5 and 6 where linked to oleic acid/oleylamine capped (OLA/OLM) silver-iron dimers (Ag-Fe3O4 OLA/OLM) and silver-iron core shell (Ag@Fe3O4 OLA/OLM) NPs via interaction between the nanoparticles and the imino group on the phthalocyanines. The phthalocyanine-NP conjugates afforded an increase in triplet quantum yields with a corresponding decrease in fluorescence quantum yield as compared to the phthalocyanine complexes alone. Complexes 3, 4 and their conjugates were then used for photodynamic antimicrobial chemotherapy on E. coli. The zwitterionic photosensitiser 4 and its conjugates showed better efficiency for photodynamic antimicrobial chemotherapy compared to their neutral counterparts.
- Full Text:
Effectiveness of different interventions to reduce occupational sitting among office administrators at Rhodes University
- Authors: Malesa, Thato
- Date: 2020
- Subjects: Standing position , Sedentary behavior , Work environment , Employee health promotion , Office furniture -- Design , Industrial hygiene , Employees -- Health risk assessment , Human engineering , Compliance
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166403 , vital:41360
- Description: Background: Sitting for prolonged periods is common in the working environment. Office workers are exposed to long periods of sitting time at work. Research has reported associations between prolonged sitting and negative health implications. As such studies have proposed different interventions aimed at reducing sitting times in the workplace. The aim of the current study was to evaluate the effectiveness of two different interventions, physical intervention (sit-stand worktables) and personal intervention (instruction to stretch) on compliance and reducing occupational sitting behaviour. The study also aimed to investigate the effectiveness of interventions in improving or impairing mood. Methods: The study took the form of a fieldbased study atRhodes University, Makhanda, South Africa. Fifteen full–time office workers in different divisions participated in the study. Participants were randomly allocated to either the physical or personal intervention group. In both intervention groups, partic ipants were prompted to stand for five minutes every hour during the workday to either work in a standing position or perform stretches. Over the course of the experiment, desk occupancy, sitting/standing time and mood effect were recorded in both intervention groups Both intervention groups were monitored for a period of three months (58 days). Results: The study found that the physical intervention group was an effective approach to reduce prolonged sitting in the workplace in comparison to the personal intervention group. Over the course of the experiment, there was sustain usage of interventions in both groups, however, in the physical intervention group desk usage decreased overtime. The findings of the study also show that some participants were more compliant with the study procedures than others. It was also found that mood improved upon introducing interventions in the workplace. However, with the outcomes of the results, the study acknowledges that several factors emerged which are likely to impact compliance, which future studies may investigate. Conclusion: Although sit-stand worktables are expensive, it seems like introducing them was successful in reducing sitting time and changing sitting behaviour in comparison to an intervention that instruct s individuals to stand up and stretch.
- Full Text:
- Authors: Malesa, Thato
- Date: 2020
- Subjects: Standing position , Sedentary behavior , Work environment , Employee health promotion , Office furniture -- Design , Industrial hygiene , Employees -- Health risk assessment , Human engineering , Compliance
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166403 , vital:41360
- Description: Background: Sitting for prolonged periods is common in the working environment. Office workers are exposed to long periods of sitting time at work. Research has reported associations between prolonged sitting and negative health implications. As such studies have proposed different interventions aimed at reducing sitting times in the workplace. The aim of the current study was to evaluate the effectiveness of two different interventions, physical intervention (sit-stand worktables) and personal intervention (instruction to stretch) on compliance and reducing occupational sitting behaviour. The study also aimed to investigate the effectiveness of interventions in improving or impairing mood. Methods: The study took the form of a fieldbased study atRhodes University, Makhanda, South Africa. Fifteen full–time office workers in different divisions participated in the study. Participants were randomly allocated to either the physical or personal intervention group. In both intervention groups, partic ipants were prompted to stand for five minutes every hour during the workday to either work in a standing position or perform stretches. Over the course of the experiment, desk occupancy, sitting/standing time and mood effect were recorded in both intervention groups Both intervention groups were monitored for a period of three months (58 days). Results: The study found that the physical intervention group was an effective approach to reduce prolonged sitting in the workplace in comparison to the personal intervention group. Over the course of the experiment, there was sustain usage of interventions in both groups, however, in the physical intervention group desk usage decreased overtime. The findings of the study also show that some participants were more compliant with the study procedures than others. It was also found that mood improved upon introducing interventions in the workplace. However, with the outcomes of the results, the study acknowledges that several factors emerged which are likely to impact compliance, which future studies may investigate. Conclusion: Although sit-stand worktables are expensive, it seems like introducing them was successful in reducing sitting time and changing sitting behaviour in comparison to an intervention that instruct s individuals to stand up and stretch.
- Full Text:
Either way you die: a collection of short stories
- Authors: Sithole, Sipho
- Date: 2020
- Subjects: South African fiction (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/145081 , vital:38406
- Description: Part A: Thesis (Creative Work); Part B: Portfolio.
- Full Text:
- Authors: Sithole, Sipho
- Date: 2020
- Subjects: South African fiction (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/145081 , vital:38406
- Description: Part A: Thesis (Creative Work); Part B: Portfolio.
- Full Text:
Elucidation of a novel role for HSP70/HSP90 organising protein (Hop) in mRNA processing
- Dingle, Laura Margaret Kirkpatrick
- Authors: Dingle, Laura Margaret Kirkpatrick
- Date: 2020
- Language: English
- Type: thesis , text , Doctoral , Ph.D
- Identifier: http://hdl.handle.net/10962/59173 , vital:27449 , doi:10.21504/10962/59173
- Description: Thesis (PhD.)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Authors: Dingle, Laura Margaret Kirkpatrick
- Date: 2020
- Language: English
- Type: thesis , text , Doctoral , Ph.D
- Identifier: http://hdl.handle.net/10962/59173 , vital:27449 , doi:10.21504/10962/59173
- Description: Thesis (PhD.)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text: