The effect of sap-sucking by Falconia intermedia (Hemiptera: Miridae) on the emission of volatile organic compounds from the leaves of Lantana camara varieties
- Heshula, Lelethu U, Hill, Martin P
- Authors: Heshula, Lelethu U , Hill, Martin P
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406141 , vital:70242 , xlink:href="https://hdl.handle.net/10520/EJC150957"
- Description: Evidence from more than 100 plant species has confirmed that plants emit volatile organic chemicals (VOC) in response to herbivory (Karban and Baldwin 1997; Dicke et al. 2003; Arimura et al. 2005). Feeding-induced plant responses may result in higher levels of volatiles, and different bouquets of compounds being emitted by plants following herbivore damage (Wei et al. 2006). The emission of volatile chemicals may be beneficial to plants in two ways; undamaged plants may interpret the chemical signals from damaged plants and in turn prime themselves for defence (Arimura et al. 2000; Dicke et al. 2003; Agrawal 2005), or volatiles emitted by damaged plants may attract natural enemies of the herbivores, which may reduce further damage to the plants (Tumlinson et al. 1993; De Moraes et al. 1998; Dicke and Vet 1999).
- Full Text:
- Date Issued: 2014
- Authors: Heshula, Lelethu U , Hill, Martin P
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406141 , vital:70242 , xlink:href="https://hdl.handle.net/10520/EJC150957"
- Description: Evidence from more than 100 plant species has confirmed that plants emit volatile organic chemicals (VOC) in response to herbivory (Karban and Baldwin 1997; Dicke et al. 2003; Arimura et al. 2005). Feeding-induced plant responses may result in higher levels of volatiles, and different bouquets of compounds being emitted by plants following herbivore damage (Wei et al. 2006). The emission of volatile chemicals may be beneficial to plants in two ways; undamaged plants may interpret the chemical signals from damaged plants and in turn prime themselves for defence (Arimura et al. 2000; Dicke et al. 2003; Agrawal 2005), or volatiles emitted by damaged plants may attract natural enemies of the herbivores, which may reduce further damage to the plants (Tumlinson et al. 1993; De Moraes et al. 1998; Dicke and Vet 1999).
- Full Text:
- Date Issued: 2014
Psychosocial impact of mental illness on family caregivers of mental healthcare users in Mangaung District
- Authors: Leburu, Maria
- Date: 2021-08
- Subjects: Home care services -- South Africa -- Mangaung -- Psychological aspects , Caregivers -- South Africa -- Mangaung
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/21770 , vital:51750
- Description: The purpose of this research study was to describe the psychosocial impact of mental illness on family caregivers of mental health care users in Mangaung district in order to explore strategies to empower mental health care users and their families to understand and to cope with mental illness problem. A qualitative, descriptive explorative and contextu al design was employed. A nonprobability, purposive sampling method was used to select participants. The target population was family caregivers from Mangaung district, whose ages were 18 years and above who were caring for mentally ill patients in their homes or admitted to a psychiatric institution. . Five focus group interviews were conducted but the first one was a pilot study. Ethical principles were maintained throughout the study as well as the concepts of trustworthiness were applied. Tesch’s approach to open coding in qualitative research was applied during data analysis. A total of six themes and twentynine sub-themes arose during data analysis and were fully discussed. Confidentiality and anonymity was ensured throughout the study. The findings suggested that most of the participants suffered psychosocial problems like stress, depression, stigma and financial constraints, although one participant indicated that she has accepted her situation of caregiving. In conclusion participants suggested that support groups should be established and awareness programmes should be put in place for community members to avoid stigmatising and laughing at caregivers, care users and family members. , Thesis (MPH) -- Faculty of Health Sciences, Public Health, 2021
- Full Text:
- Date Issued: 2021-08
- Authors: Leburu, Maria
- Date: 2021-08
- Subjects: Home care services -- South Africa -- Mangaung -- Psychological aspects , Caregivers -- South Africa -- Mangaung
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/21770 , vital:51750
- Description: The purpose of this research study was to describe the psychosocial impact of mental illness on family caregivers of mental health care users in Mangaung district in order to explore strategies to empower mental health care users and their families to understand and to cope with mental illness problem. A qualitative, descriptive explorative and contextu al design was employed. A nonprobability, purposive sampling method was used to select participants. The target population was family caregivers from Mangaung district, whose ages were 18 years and above who were caring for mentally ill patients in their homes or admitted to a psychiatric institution. . Five focus group interviews were conducted but the first one was a pilot study. Ethical principles were maintained throughout the study as well as the concepts of trustworthiness were applied. Tesch’s approach to open coding in qualitative research was applied during data analysis. A total of six themes and twentynine sub-themes arose during data analysis and were fully discussed. Confidentiality and anonymity was ensured throughout the study. The findings suggested that most of the participants suffered psychosocial problems like stress, depression, stigma and financial constraints, although one participant indicated that she has accepted her situation of caregiving. In conclusion participants suggested that support groups should be established and awareness programmes should be put in place for community members to avoid stigmatising and laughing at caregivers, care users and family members. , Thesis (MPH) -- Faculty of Health Sciences, Public Health, 2021
- Full Text:
- Date Issued: 2021-08
Development and optimisation of a qPCR assay for the enumeration of Cryptophlebia leucotreta granulovirus (CrleGV) used for commercial applications
- Authors: Mela, Thuthula
- Date: 2022-10-14
- Subjects: Cryptophlebia leucotreta granulovirus , Cryptophlebia leucotreta , Late expression factor 8 (LEF-8) , Late expression factor 9 , Dark field microscopy , Genomic DNA , Polymerase chain reaction , Plasmids
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/362949 , vital:65377
- Description: The citrus industry contributes significantly to the South African agricultural sector. Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is highly important to the South African citrus industry as it is classified as a phytosanitary pest by most international markets. Thaumatotibia leucotreta has caused an estimated annual loss of up to R100 million to the industry. In order to control T. leucotreta in South Africa, an integrated pest management (IPM) programme has been used. One of the components of this programme is Cryptophlebia leucotreta granulovirus (CrleGV), which has been formulated to a registered biopesticide namely Cryptogran and has been successfully applied in the field for over 15 years. To use CrleGV as biopesticides, quantification of the viral particles is required to perform bioassays for field trials and formulation, among other applications. Darkfield microscopy is a traditional method used for the quantification of CrleGV; however, the method is characterised as being subjective, tedious, labour intensive, and time-consuming. This study aims to develop and optimise a qPCR technique to accurately quantify CrleGV-SA OBs using plasmid DNA for downstream applications. Firstly, lef-8, lef-9, and granulin conserved genes from CrleGV-SA and CrleGV-CV3 genome sequences were analysed by performing multiple alignments to evaluate the degree of identity between these genes. This was done to design two sets of oligonucleotides (internal and external) from regions with the highest identity. Subsequently, in silico testing was done to evaluate the designed oligonucleotides to determine whether they specifically bind to the selected target regions. Secondly, three sets of DNA plasmids (pJET1.2-Gran, pJET1.2-lef-9, and pJET1.2-lef-8) were constructed, each containing a target region for either granulin, lef-9, and lef-8 genes for use as standards in a downstream qPCR assay. This was achieved by first extracting gDNA from CrleGV-SA OBs and using the gDNA as a template to PCR amplify the target regions of the selected gene regions with the designed oligonucleotides. Subsequently, the PCR amplified regions were then directly ligated into the pJET1.2/blunt vector, and the plasmids were confirmed by colony PCR, restriction enzyme digestion, and Sanger sequencing. Thirdly, two different methods of CrleGV-SA gDNA extraction were compared to determine which method has the best yields in terms of concentration. The extraction methods compared were the Quick-DNA Miniprep Plus kit according to manufacturer’s instructions (Method 1a), pre-treatment with Na2CO3 prior to using the Quick-DNA Miniprep Plus kit (Method 1b), pre- treatment with Na2CO3, and neutralisation with Tris-HCl prior to gDNA extraction using the Quick-DNA Miniprep Plus kit (Method 1c) and the CTAB method (Method 2). The gDNA concentration and purity for all samples were determined using a Nanodrop spectrophotometer. Method 1c (Na2CO3 and Tris-HCl pre-treated plus Quick-DNA Miniprep Plus kit) was the most efficient at extracting genomic DNA compared with the other methods, resulting in the highest DNA concentration in short processing time. Fourthly, plasmid standards were evaluated for use in the qPCR assay. This was done as it was important to consider the efficacy of the oligonucleotides; including the ability of the oligonucleotides to anneal to the appropriate segment of DNA without extensive formation of oligonucleotides dimers, non-specific annealing, or formation of secondary structure. In addition, it was done to ensure that highly accurate standard curves were generated. The standard curves were to be utilised in the downstream qPCR assay to determine the quantity of test samples by interpolation, reading from the values within the standard curve. Lastly, darkfield microscopy and qPCR methods of enumeration were compared to verify their accuracy and determine the most consistent and comparable method. This was achieved by quantifying the purified, crude-purified, and viral formulated CrleGV-SA suspensions using these methods. Subsequently, a statistical analysis was conducted to compare the results produced by the two enumeration methods. The obtained results showed that the granulin, lef- 8 and lef-9 qPCR values did not significantly differ from the darkfield microscopy results. The findings of this study revealed that the two assays, lef-8 qPCR and lef-9 qPCR, were more robust, sensitive, and efficient for the quantification of CrleGV-SA. Thus, this study has successfully developed a qPCR assay that is comparable with the traditional darkfield microscopy counting technique. This is the first study to use the qPCR technique to enumerate CrleGV-SA using plasmid standards. The developed qPCR assay is reliable, rapid, and cost- effective and has a great potential to be used as an alternative method to darkfield microscopy in the laboratory and commercial settings. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-10-14
- Authors: Mela, Thuthula
- Date: 2022-10-14
- Subjects: Cryptophlebia leucotreta granulovirus , Cryptophlebia leucotreta , Late expression factor 8 (LEF-8) , Late expression factor 9 , Dark field microscopy , Genomic DNA , Polymerase chain reaction , Plasmids
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/362949 , vital:65377
- Description: The citrus industry contributes significantly to the South African agricultural sector. Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is highly important to the South African citrus industry as it is classified as a phytosanitary pest by most international markets. Thaumatotibia leucotreta has caused an estimated annual loss of up to R100 million to the industry. In order to control T. leucotreta in South Africa, an integrated pest management (IPM) programme has been used. One of the components of this programme is Cryptophlebia leucotreta granulovirus (CrleGV), which has been formulated to a registered biopesticide namely Cryptogran and has been successfully applied in the field for over 15 years. To use CrleGV as biopesticides, quantification of the viral particles is required to perform bioassays for field trials and formulation, among other applications. Darkfield microscopy is a traditional method used for the quantification of CrleGV; however, the method is characterised as being subjective, tedious, labour intensive, and time-consuming. This study aims to develop and optimise a qPCR technique to accurately quantify CrleGV-SA OBs using plasmid DNA for downstream applications. Firstly, lef-8, lef-9, and granulin conserved genes from CrleGV-SA and CrleGV-CV3 genome sequences were analysed by performing multiple alignments to evaluate the degree of identity between these genes. This was done to design two sets of oligonucleotides (internal and external) from regions with the highest identity. Subsequently, in silico testing was done to evaluate the designed oligonucleotides to determine whether they specifically bind to the selected target regions. Secondly, three sets of DNA plasmids (pJET1.2-Gran, pJET1.2-lef-9, and pJET1.2-lef-8) were constructed, each containing a target region for either granulin, lef-9, and lef-8 genes for use as standards in a downstream qPCR assay. This was achieved by first extracting gDNA from CrleGV-SA OBs and using the gDNA as a template to PCR amplify the target regions of the selected gene regions with the designed oligonucleotides. Subsequently, the PCR amplified regions were then directly ligated into the pJET1.2/blunt vector, and the plasmids were confirmed by colony PCR, restriction enzyme digestion, and Sanger sequencing. Thirdly, two different methods of CrleGV-SA gDNA extraction were compared to determine which method has the best yields in terms of concentration. The extraction methods compared were the Quick-DNA Miniprep Plus kit according to manufacturer’s instructions (Method 1a), pre-treatment with Na2CO3 prior to using the Quick-DNA Miniprep Plus kit (Method 1b), pre- treatment with Na2CO3, and neutralisation with Tris-HCl prior to gDNA extraction using the Quick-DNA Miniprep Plus kit (Method 1c) and the CTAB method (Method 2). The gDNA concentration and purity for all samples were determined using a Nanodrop spectrophotometer. Method 1c (Na2CO3 and Tris-HCl pre-treated plus Quick-DNA Miniprep Plus kit) was the most efficient at extracting genomic DNA compared with the other methods, resulting in the highest DNA concentration in short processing time. Fourthly, plasmid standards were evaluated for use in the qPCR assay. This was done as it was important to consider the efficacy of the oligonucleotides; including the ability of the oligonucleotides to anneal to the appropriate segment of DNA without extensive formation of oligonucleotides dimers, non-specific annealing, or formation of secondary structure. In addition, it was done to ensure that highly accurate standard curves were generated. The standard curves were to be utilised in the downstream qPCR assay to determine the quantity of test samples by interpolation, reading from the values within the standard curve. Lastly, darkfield microscopy and qPCR methods of enumeration were compared to verify their accuracy and determine the most consistent and comparable method. This was achieved by quantifying the purified, crude-purified, and viral formulated CrleGV-SA suspensions using these methods. Subsequently, a statistical analysis was conducted to compare the results produced by the two enumeration methods. The obtained results showed that the granulin, lef- 8 and lef-9 qPCR values did not significantly differ from the darkfield microscopy results. The findings of this study revealed that the two assays, lef-8 qPCR and lef-9 qPCR, were more robust, sensitive, and efficient for the quantification of CrleGV-SA. Thus, this study has successfully developed a qPCR assay that is comparable with the traditional darkfield microscopy counting technique. This is the first study to use the qPCR technique to enumerate CrleGV-SA using plasmid standards. The developed qPCR assay is reliable, rapid, and cost- effective and has a great potential to be used as an alternative method to darkfield microscopy in the laboratory and commercial settings. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-10-14
Studies on vine storage methods, planting techniques, paclobutrazol treatment, planting density and weevil management on sweetpotato (ipomoea batatas l.lam) cultivars promoted in South Africa
- Hlerema, Igenicious Nicholas https://orcid.org/0000-0002-6111-404X
- Authors: Hlerema, Igenicious Nicholas https://orcid.org/0000-0002-6111-404X
- Date: 2019-09
- Subjects: Sweet potatoes , Seed treatment
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21580 , vital:49336
- Description: Sweetpotato (Ipomoea batatas L. LAM) is a major world staple food. It is a versatile, nutrient-rich crop well suited for production by emerging farmers, and thus a popular crop in subtropical parts of South Africa. The crop has several advantages such as producing more bioweight and nutrients per unit land area and per unit time than most other staple crops such as maize; adaptation to a broad range of agro-ecological conditions; and ability to compete and crowd out weeds, and affected by a relatively small number of pests and diseases. Root and vine yields achieved by emerging farmers are low and cultivation systems need to be optimized. The general objective of the research was to develop nursery practices that ensure a sustainable supply of sweetpotato planting materials and cultural practices that maximize yield, eating and nutritional quality of sweetpotato roots. The specific objectives were (i) to evaluate the effect of polyethylene and hessian bags on vine quality and vine survival period; (ii) to compare planting techniques and vine length; (iii) to determine the effect of paclobutrazol on storage root yield; and (iv) to evaluate the effect of Beauveria bassiana as biological control for sweetpotato weevil. The vine storage experiment aimed at identifying the best type of storage bags that keep the vines of “Bophelo”, an orange-fleshed sweetpotato cultivar in good quality for a longer period of time. The study involved two factors, viz storage bag type and storage period. The experiment tried to address (1) a sustainable seed system in sweetpotato and (2) production stimulated by cultural practises. Vines were stored in polyethylene bag without holes, polyethylene bag with 12 holes and dry hessian bag over 3, 6, 9, 12 and 15 days at an ambient temperature of 250C. The incremental cost-effectiveness ratio (ICER) was calculated to determine the cost-effectiveness of using the polyethylene bags with holes or without and the hessian bags. The results of the study showed that hessian bags store vines over a longer period (12 days) compared to the polyethylene bags without holes (6 days); however, hessian bags are more expensive. Polyethylene bags can still be used for transporting and storing vines if the farmer is within a short distance from the seed source and plants the vines within the 6 day period. Polyethylene bags with 12 holes are recommended since they allow maximum air circulation and extend storage period (9 days). Optimum planting techniques can help sweetpotato farmers to achieve optimal yields. Newly developed cultivars from the Agricultural Research Council have not been tested to determine the best planting techniques. A trial was conducted to investigate the effect of two planting orientations (horizontal and vertical) and different vine length (2, 3 and 4 subterranean nodes) of 3 released varieties, Blesbock, Bophelo and Ndou on storage root yield of sweetpotato. A factorial experiment was laid out in a randomised complete block design with three replications during two cropping seasons (2014/15 and 2015/16). The data collected in both experiments included total storage root yield, marketable storage root yield, and number of storage roots per size class. Significant differences were detected for the interaction of all factors on the number roots per size class, total storage root yield, and total average root weight. Vertical and horizontal planting per se showed no significance differences for all the sweetpotato root growth parameters such as total yield. However, the more the number of subterainian node the more yield we got for the commercial cultivar Blesbok. Paclobutrazol (PBZ) is a plant growth retardant hormone. This hormone might, therefore, be useful for sweetpotato growers to achieve higher plant populations per hectare because it would reduce the plant canopy. However, it should also be checked if the PBZ application does not affect nutrient content of roots and leaves, especially the beta-carotene content of the orange-fleshed cultivars. The objective of this study was, therefore, to determine the effect of PBZ on sweetpotato shoot growth, storage root yield and beta-carotene content of sweetpotato leaves and storage roots. The field trial was repeated over two seasons, namely 2014/15 and 2015/16 crop seasons. These field experiments were arranged as a split plot experiment. The main plots were allocated to four PBZ levels, laid-out as randomised complete block design, and treatment combinations of two cultivars (Bophelo and Blesbok) and two plants spacing (20 cm and 30 cm) were randomly allocated into the subplots. The PBZ levels applied were 0, 100, 200 and 300 mg of active ingredient per litre of water, sprayed 4 weeks after planting. Root yield and bioweight accumulation were recorded. In addition, a pot experiment was set up using cultivar Bophelo and 0 mg, 100 mg and 200 mg/l active ingredient of PBZ sprayed 4 weeks after planting. Leaf and root samples (150g and 400g of a composite sample respectively) were collected and analysed for total phenols, total flavonoids, vitamin C and beta-carotene. The field trial results revealed significant differences (P<0.05) in leaf and stem weight of the plants treated with different PBZ levels applied. The control (0 mg PBZ rate) had the highest leaf and stem weight. There were no significant differences in root yield among the PBZ levels. The results of leaf and root analysis for the Bophelo cultivar showed significant differences (P<0.05) in total phenols, total flavonoids, vitamin C and beta-carotene in leaf samples of the three levels of PBZ applied. The beta-carotene for the leaf increased at the 100 mg/l PBZ level. As the paclobutrazol level increased there was a reduction in the beta-carotene content for the roots from 18,91 to 13,97 to 10,77 mg/100g dry weight for 0 mg/l, 100 mg/l and 200mg/l, respectively. Application of PBZ to sweetpotato reduces the bioweight yield but does not have an effect on the root yield. Thus a higher plant density can be used to achieve higher yield and returns on investment. The leaves can be used as a relish and can be sold to supplement income. However, PBZ further reduces the beta-carotene content of the roots and is not recommended for use with orange-fleshed cultivars, where the objective is to enrich food with vitamin A. Sweetpotato weevils (Cylas puncticollis and C. formicarius) are notorious pests of sweetpotato. It causes severe losses in marketable root yield. The study tested the use of Beauveria bassiana (Balsamo Vuillemin) (Deuteromycota: Hyphomycetes) for controlling sweetpotato weevils. Experiments were conducted over two cropping seasons using four treatments: 1) dipping sweetpotato cuttings in solution of 1 g/litre B. bassiana before planting, 2) spraying with a registered chemical (Deltametrin) at 50 ml/100 litre of water starting 2 weeks after panting at biweekly basis for four months after planting, 3) spraying the leaves with B. bassiana (10 g/100 litre) starting 2 weeks on biweekly basis for four months after planting; and 4) control (sprayed with water). The research was arranged as split plot experiment, where the pest management treatments assigned to the main plots as per Latin square design and the three sweetpotato cultivars (Bophelo, Ndou and Blesbok) were randomly put in the subplot in each main plot. Spraying with B. bassiana significantly reduced the percentage of insect-damaged roots (9.95percent) compared to the control (22.48percent). Dipping sweetpotato cuttings in solution of 1 g/litre B. bassiana before planting did not significantly reduce the number of insect damaged roots (18.63percent insect damage). There was no significant difference between the chemical spray (8.2percent insect damage) and spraying with B. bassiana (9.95percent insect damage). The investigation indicated that B. bassiana can be considered as an alternative control method for the sweetpotato weevil. Use of biological control is less expensive and beneficial to reduce adverse effects on the environment and human health. , Thesis (PhD) -- Faculty of Science and Agriculture, 2019
- Full Text:
- Date Issued: 2019-09
- Authors: Hlerema, Igenicious Nicholas https://orcid.org/0000-0002-6111-404X
- Date: 2019-09
- Subjects: Sweet potatoes , Seed treatment
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21580 , vital:49336
- Description: Sweetpotato (Ipomoea batatas L. LAM) is a major world staple food. It is a versatile, nutrient-rich crop well suited for production by emerging farmers, and thus a popular crop in subtropical parts of South Africa. The crop has several advantages such as producing more bioweight and nutrients per unit land area and per unit time than most other staple crops such as maize; adaptation to a broad range of agro-ecological conditions; and ability to compete and crowd out weeds, and affected by a relatively small number of pests and diseases. Root and vine yields achieved by emerging farmers are low and cultivation systems need to be optimized. The general objective of the research was to develop nursery practices that ensure a sustainable supply of sweetpotato planting materials and cultural practices that maximize yield, eating and nutritional quality of sweetpotato roots. The specific objectives were (i) to evaluate the effect of polyethylene and hessian bags on vine quality and vine survival period; (ii) to compare planting techniques and vine length; (iii) to determine the effect of paclobutrazol on storage root yield; and (iv) to evaluate the effect of Beauveria bassiana as biological control for sweetpotato weevil. The vine storage experiment aimed at identifying the best type of storage bags that keep the vines of “Bophelo”, an orange-fleshed sweetpotato cultivar in good quality for a longer period of time. The study involved two factors, viz storage bag type and storage period. The experiment tried to address (1) a sustainable seed system in sweetpotato and (2) production stimulated by cultural practises. Vines were stored in polyethylene bag without holes, polyethylene bag with 12 holes and dry hessian bag over 3, 6, 9, 12 and 15 days at an ambient temperature of 250C. The incremental cost-effectiveness ratio (ICER) was calculated to determine the cost-effectiveness of using the polyethylene bags with holes or without and the hessian bags. The results of the study showed that hessian bags store vines over a longer period (12 days) compared to the polyethylene bags without holes (6 days); however, hessian bags are more expensive. Polyethylene bags can still be used for transporting and storing vines if the farmer is within a short distance from the seed source and plants the vines within the 6 day period. Polyethylene bags with 12 holes are recommended since they allow maximum air circulation and extend storage period (9 days). Optimum planting techniques can help sweetpotato farmers to achieve optimal yields. Newly developed cultivars from the Agricultural Research Council have not been tested to determine the best planting techniques. A trial was conducted to investigate the effect of two planting orientations (horizontal and vertical) and different vine length (2, 3 and 4 subterranean nodes) of 3 released varieties, Blesbock, Bophelo and Ndou on storage root yield of sweetpotato. A factorial experiment was laid out in a randomised complete block design with three replications during two cropping seasons (2014/15 and 2015/16). The data collected in both experiments included total storage root yield, marketable storage root yield, and number of storage roots per size class. Significant differences were detected for the interaction of all factors on the number roots per size class, total storage root yield, and total average root weight. Vertical and horizontal planting per se showed no significance differences for all the sweetpotato root growth parameters such as total yield. However, the more the number of subterainian node the more yield we got for the commercial cultivar Blesbok. Paclobutrazol (PBZ) is a plant growth retardant hormone. This hormone might, therefore, be useful for sweetpotato growers to achieve higher plant populations per hectare because it would reduce the plant canopy. However, it should also be checked if the PBZ application does not affect nutrient content of roots and leaves, especially the beta-carotene content of the orange-fleshed cultivars. The objective of this study was, therefore, to determine the effect of PBZ on sweetpotato shoot growth, storage root yield and beta-carotene content of sweetpotato leaves and storage roots. The field trial was repeated over two seasons, namely 2014/15 and 2015/16 crop seasons. These field experiments were arranged as a split plot experiment. The main plots were allocated to four PBZ levels, laid-out as randomised complete block design, and treatment combinations of two cultivars (Bophelo and Blesbok) and two plants spacing (20 cm and 30 cm) were randomly allocated into the subplots. The PBZ levels applied were 0, 100, 200 and 300 mg of active ingredient per litre of water, sprayed 4 weeks after planting. Root yield and bioweight accumulation were recorded. In addition, a pot experiment was set up using cultivar Bophelo and 0 mg, 100 mg and 200 mg/l active ingredient of PBZ sprayed 4 weeks after planting. Leaf and root samples (150g and 400g of a composite sample respectively) were collected and analysed for total phenols, total flavonoids, vitamin C and beta-carotene. The field trial results revealed significant differences (P<0.05) in leaf and stem weight of the plants treated with different PBZ levels applied. The control (0 mg PBZ rate) had the highest leaf and stem weight. There were no significant differences in root yield among the PBZ levels. The results of leaf and root analysis for the Bophelo cultivar showed significant differences (P<0.05) in total phenols, total flavonoids, vitamin C and beta-carotene in leaf samples of the three levels of PBZ applied. The beta-carotene for the leaf increased at the 100 mg/l PBZ level. As the paclobutrazol level increased there was a reduction in the beta-carotene content for the roots from 18,91 to 13,97 to 10,77 mg/100g dry weight for 0 mg/l, 100 mg/l and 200mg/l, respectively. Application of PBZ to sweetpotato reduces the bioweight yield but does not have an effect on the root yield. Thus a higher plant density can be used to achieve higher yield and returns on investment. The leaves can be used as a relish and can be sold to supplement income. However, PBZ further reduces the beta-carotene content of the roots and is not recommended for use with orange-fleshed cultivars, where the objective is to enrich food with vitamin A. Sweetpotato weevils (Cylas puncticollis and C. formicarius) are notorious pests of sweetpotato. It causes severe losses in marketable root yield. The study tested the use of Beauveria bassiana (Balsamo Vuillemin) (Deuteromycota: Hyphomycetes) for controlling sweetpotato weevils. Experiments were conducted over two cropping seasons using four treatments: 1) dipping sweetpotato cuttings in solution of 1 g/litre B. bassiana before planting, 2) spraying with a registered chemical (Deltametrin) at 50 ml/100 litre of water starting 2 weeks after panting at biweekly basis for four months after planting, 3) spraying the leaves with B. bassiana (10 g/100 litre) starting 2 weeks on biweekly basis for four months after planting; and 4) control (sprayed with water). The research was arranged as split plot experiment, where the pest management treatments assigned to the main plots as per Latin square design and the three sweetpotato cultivars (Bophelo, Ndou and Blesbok) were randomly put in the subplot in each main plot. Spraying with B. bassiana significantly reduced the percentage of insect-damaged roots (9.95percent) compared to the control (22.48percent). Dipping sweetpotato cuttings in solution of 1 g/litre B. bassiana before planting did not significantly reduce the number of insect damaged roots (18.63percent insect damage). There was no significant difference between the chemical spray (8.2percent insect damage) and spraying with B. bassiana (9.95percent insect damage). The investigation indicated that B. bassiana can be considered as an alternative control method for the sweetpotato weevil. Use of biological control is less expensive and beneficial to reduce adverse effects on the environment and human health. , Thesis (PhD) -- Faculty of Science and Agriculture, 2019
- Full Text:
- Date Issued: 2019-09
Perceptions of the role of Lantana camara on human well-being and rural livelihoods in Vhembe Biosphere Reserve, South Africa
- Authors: Mhlongo, Edward Swazi
- Date: 2021-04
- Subjects: Lantana camara -- South Africa -- Vhembe District Municipality , Introduced organisms -- South Africa -- Vhembe District Municipality , Biological invasions -- South Africa -- Vhembe District Municipality , Plant invasions -- South Africa -- Vhembe District Municipality , Lantana camara -- Control -- South Africa -- Vhembe District Municipality , South Africa -- Rural conditions , Ethnoscience -- South Africa -- Vhembe District Municipality
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177952 , vital:42893
- Description: In the past, social aspects on biological invasions were less documented, this hindered the development of sound and effective management of Invasive Alien Species (IAS). However, there has been a shift in trends with more studies on biological invasions integrating local knowledge together with ecological studies to develop effective management interventions. Invasive Alien Species are widespread throughout Southern Africa and are usually prevalent in the rural areas. Limpopo province consists of large rural areas where people depend on natural resources, wild and exotic species for their livelihoods. Lantana camara is one of the major invaders that is problematic worldwide having detrimental impacts on biodiversity, ecosystem functions, and economies. This study assessed the perceptions of the role of L. camara on the well-being and rural livelihoods of local communities in the Vhembe Biosphere Reserve using household surveys. A total of 300 surveys were administered in six villages. The study further used a two-pronged approach to examine invasion extent and management options. The two-pronged approach included (i) detailed vegetation surveys in 50 household yards within each village, and (ii) focus group to solicit local knowledge of invasion extent and managing L. camara by the rural communities. The results of the study showed that almost all the respondents knew L. camara and could describe it. Most of the respondents were of the view that L. camara had no negative impacts on their livelihoods. Other respondents stated costs associated with L. camara were more than benefits and wanted a reduction in L. camara densities in the area. Most respondents wanted more government intervention to help in managing L. camara, this is because of the perceived future impacts of L. camara. Vegetation survey results showed no significant difference in L. camara abundances and plant heights among the six study villages. The average number of L. camara counted per household yard in all villages was (2.41 ± 0.20) plants, with average plant basal diameter of (0.94 ± 0.02 cm). There were significant differences in canopy width of L. camara among the six study villages. Plant basal diameter was high in Tshakhuma (1.05 ± 0.04 m) and Duthuni (1.00 ± 0.04 m) villages, and low in Ha Mutsha village (0.82 ± 0.03 m). Lantana camara canopy width at household level across all villages averaged 1.34 ± 0.03 m. Canopy cover was high in Tshakhuma village (1.70 ± 0.09 m) and low at Ha Mutsha village (1.03 ± 0.03 m). In all six village focus group discussions, it was noted that mechanical clearing of L. camara was the most used method, but they reported minimum help from the government particularly Working for Water (WfW). The study concludes that L. camara has no substantial adverse impacts to most of the respondents. The study further noted that L. camara is dominant in most household yards ii and that management is taking place however current control options are not enough on their own. Suggestions for further research are to explore more alternative indigenous species present or easily accessible to the community members which may offer the same benefits as IAS. Furthermore, additional research at local level is required for implementing management techniques best suited for the area. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mhlongo, Edward Swazi
- Date: 2021-04
- Subjects: Lantana camara -- South Africa -- Vhembe District Municipality , Introduced organisms -- South Africa -- Vhembe District Municipality , Biological invasions -- South Africa -- Vhembe District Municipality , Plant invasions -- South Africa -- Vhembe District Municipality , Lantana camara -- Control -- South Africa -- Vhembe District Municipality , South Africa -- Rural conditions , Ethnoscience -- South Africa -- Vhembe District Municipality
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177952 , vital:42893
- Description: In the past, social aspects on biological invasions were less documented, this hindered the development of sound and effective management of Invasive Alien Species (IAS). However, there has been a shift in trends with more studies on biological invasions integrating local knowledge together with ecological studies to develop effective management interventions. Invasive Alien Species are widespread throughout Southern Africa and are usually prevalent in the rural areas. Limpopo province consists of large rural areas where people depend on natural resources, wild and exotic species for their livelihoods. Lantana camara is one of the major invaders that is problematic worldwide having detrimental impacts on biodiversity, ecosystem functions, and economies. This study assessed the perceptions of the role of L. camara on the well-being and rural livelihoods of local communities in the Vhembe Biosphere Reserve using household surveys. A total of 300 surveys were administered in six villages. The study further used a two-pronged approach to examine invasion extent and management options. The two-pronged approach included (i) detailed vegetation surveys in 50 household yards within each village, and (ii) focus group to solicit local knowledge of invasion extent and managing L. camara by the rural communities. The results of the study showed that almost all the respondents knew L. camara and could describe it. Most of the respondents were of the view that L. camara had no negative impacts on their livelihoods. Other respondents stated costs associated with L. camara were more than benefits and wanted a reduction in L. camara densities in the area. Most respondents wanted more government intervention to help in managing L. camara, this is because of the perceived future impacts of L. camara. Vegetation survey results showed no significant difference in L. camara abundances and plant heights among the six study villages. The average number of L. camara counted per household yard in all villages was (2.41 ± 0.20) plants, with average plant basal diameter of (0.94 ± 0.02 cm). There were significant differences in canopy width of L. camara among the six study villages. Plant basal diameter was high in Tshakhuma (1.05 ± 0.04 m) and Duthuni (1.00 ± 0.04 m) villages, and low in Ha Mutsha village (0.82 ± 0.03 m). Lantana camara canopy width at household level across all villages averaged 1.34 ± 0.03 m. Canopy cover was high in Tshakhuma village (1.70 ± 0.09 m) and low at Ha Mutsha village (1.03 ± 0.03 m). In all six village focus group discussions, it was noted that mechanical clearing of L. camara was the most used method, but they reported minimum help from the government particularly Working for Water (WfW). The study concludes that L. camara has no substantial adverse impacts to most of the respondents. The study further noted that L. camara is dominant in most household yards ii and that management is taking place however current control options are not enough on their own. Suggestions for further research are to explore more alternative indigenous species present or easily accessible to the community members which may offer the same benefits as IAS. Furthermore, additional research at local level is required for implementing management techniques best suited for the area. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2021
- Full Text:
- Date Issued: 2021-04
The modulation of the photophysical and photodynamic therapy activities of a phthalocyanine by detonation nanodiamonds: Comparison with graphene quantum dots and carbon nanodots
- Matshitse, Refilwe, Managa, Muthumuni, Nyokong, Tebello
- Authors: Matshitse, Refilwe , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186690 , vital:44525 , xlink:href="https://doi.org/10.1016/j.diamond.2019.107617"
- Description: A positively charged phthalocyanine (2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]-phthalocyanine (ZnTPPcQ)) was non-covalently linked to carbon based nanoparticles: detonation nanodiamonds (DNDs), carbon dots (CDs) and graphene quantum dots (GQDs) to form nanosembles of DNDs-ZnTPPcQ, GQDs-ZnTPPcQ and CDs-ZnTPPcQ, respectively. Irrespective of its small size and the least number of Pcs (41.67 μg loading per milligram of DNDs), DNDs-ZnTPPcQ gave the highest singlet oxygen quantum yield (0.62) in dimethyl sulfoxide compared to the rest of the conjugates. This resulted in superior PDT activity against MCF7 breast cancer lines, with the lowest cell viability of 28% compared to ZnTPPcQ-CDs and ZnTPPcQ-GQDs at 30.1 ± 0.02% and 31.4 ± 0.23%, respectively.
- Full Text:
- Date Issued: 2020
- Authors: Matshitse, Refilwe , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186690 , vital:44525 , xlink:href="https://doi.org/10.1016/j.diamond.2019.107617"
- Description: A positively charged phthalocyanine (2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]-phthalocyanine (ZnTPPcQ)) was non-covalently linked to carbon based nanoparticles: detonation nanodiamonds (DNDs), carbon dots (CDs) and graphene quantum dots (GQDs) to form nanosembles of DNDs-ZnTPPcQ, GQDs-ZnTPPcQ and CDs-ZnTPPcQ, respectively. Irrespective of its small size and the least number of Pcs (41.67 μg loading per milligram of DNDs), DNDs-ZnTPPcQ gave the highest singlet oxygen quantum yield (0.62) in dimethyl sulfoxide compared to the rest of the conjugates. This resulted in superior PDT activity against MCF7 breast cancer lines, with the lowest cell viability of 28% compared to ZnTPPcQ-CDs and ZnTPPcQ-GQDs at 30.1 ± 0.02% and 31.4 ± 0.23%, respectively.
- Full Text:
- Date Issued: 2020
Synthesis and nonlinear optical examination of 3 (4), 15 (16)-Bis-(4-tert-butyl-phenoxy)-10, 22-diaminohemiporphyrazinato chloroindium
- Britton, Jonathan, Antunes, Edith M, Nyokong, Tebello
- Authors: Britton, Jonathan , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241739 , vital:50965 , xlink:href="https://doi.org/10.1016/j.molstruc.2013.05.001"
- Description: 3(4),15(16)-Bis-(4-tert-butyl-phenoxy)-10,22-diaminohemiporphyrazinato chloroindium hemiporphyrazine was synthesized from 1,3,5-triaminobenzene and 4-tert-butyl-phenoxyisoindoline. The structure of the complex was confirmed using mass, nuclear magnetic resonance and infrared spectroscopies. The nonlinear parameters of the compound was also analyzed in dimethylformamide and found to be significantly greater than previously analyzed phthalocyanines.
- Full Text:
- Date Issued: 2013
- Authors: Britton, Jonathan , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241739 , vital:50965 , xlink:href="https://doi.org/10.1016/j.molstruc.2013.05.001"
- Description: 3(4),15(16)-Bis-(4-tert-butyl-phenoxy)-10,22-diaminohemiporphyrazinato chloroindium hemiporphyrazine was synthesized from 1,3,5-triaminobenzene and 4-tert-butyl-phenoxyisoindoline. The structure of the complex was confirmed using mass, nuclear magnetic resonance and infrared spectroscopies. The nonlinear parameters of the compound was also analyzed in dimethylformamide and found to be significantly greater than previously analyzed phthalocyanines.
- Full Text:
- Date Issued: 2013
Spectroscopic and nonlinear optical properties of the four positional isomers of 4α-(4-tert-butylphenoxy) phthalocyanine
- Ngubeni, Grace N, Britton, Jonathan, Mack, John, New, Edward, Hancox, Ian, Walker, Marc, Nyokong, Tebello, Jones, Tim S, Khene,Samson M
- Authors: Ngubeni, Grace N , Britton, Jonathan , Mack, John , New, Edward , Hancox, Ian , Walker, Marc , Nyokong, Tebello , Jones, Tim S , Khene,Samson M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241448 , vital:50940 , xlink:href="https://doi.org/10.1039/C5TC01601K"
- Description: The spectroscopic and nonlinear optical properties of the positional isomers of metal free 4α-(4-tert-butylphenoxy) phthalocyanine are presented. Second order nonlinear polarizability (β), imaginary hyperpolarizability (Im(γ)) and imaginary susceptibility (Im[χ(3)]) values were determined for the four positional isomers. The measured β values of the four isomers displayed the following trend, C4h (34.0 × 10−5 m MW−1) > D2h (28.8 × 10−5 m MW−1) > C2v (22.8 × 10−5 m MW−1) > Cs (13.7 × 10−5 m MW−1).
- Full Text:
- Date Issued: 2015
- Authors: Ngubeni, Grace N , Britton, Jonathan , Mack, John , New, Edward , Hancox, Ian , Walker, Marc , Nyokong, Tebello , Jones, Tim S , Khene,Samson M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241448 , vital:50940 , xlink:href="https://doi.org/10.1039/C5TC01601K"
- Description: The spectroscopic and nonlinear optical properties of the positional isomers of metal free 4α-(4-tert-butylphenoxy) phthalocyanine are presented. Second order nonlinear polarizability (β), imaginary hyperpolarizability (Im(γ)) and imaginary susceptibility (Im[χ(3)]) values were determined for the four positional isomers. The measured β values of the four isomers displayed the following trend, C4h (34.0 × 10−5 m MW−1) > D2h (28.8 × 10−5 m MW−1) > C2v (22.8 × 10−5 m MW−1) > Cs (13.7 × 10−5 m MW−1).
- Full Text:
- Date Issued: 2015
Evaluation of water quality, selected metals and endocrine-disrupting compounds in the rivers and municipal wastewaters of Eastern Cape province, South Africa
- Authors: Farounbi, Adebayo Ibikunle
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177327 , vital:42810
- Description: Thesis embargoed. Release date April 2022. , Thesis (PhD) -- Faculty of Science, Institute of Water Research, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Farounbi, Adebayo Ibikunle
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177327 , vital:42810
- Description: Thesis embargoed. Release date April 2022. , Thesis (PhD) -- Faculty of Science, Institute of Water Research, 2021
- Full Text:
- Date Issued: 2021-04
Active learning in schools
- Lotz-Sisitka, Heila, Timmermans, Ingrid
- Authors: Lotz-Sisitka, Heila , Timmermans, Ingrid
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389696 , vital:68475 , xlink:href="https://eeasa.org.za/wp-content/uploads/2016/12/Bulletin_vol21-_Sep-2001.pdf"
- Description: The Rhodes University Environmental Education Unit has initiated a project to support school-based environmental education work in Grahamstown. In line with national environmental education policy, the project supports a focus on environmental learning in the context of the OBE curriculum, and provides professional development support to teachers implementing the project (NEEP, 2000). An action research evaluation is taking place to monitor key aspects of the project and a number of interim evaluation reports have been produced (Mbanjwa, 2001).
- Full Text:
- Date Issued: 2001
- Authors: Lotz-Sisitka, Heila , Timmermans, Ingrid
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/389696 , vital:68475 , xlink:href="https://eeasa.org.za/wp-content/uploads/2016/12/Bulletin_vol21-_Sep-2001.pdf"
- Description: The Rhodes University Environmental Education Unit has initiated a project to support school-based environmental education work in Grahamstown. In line with national environmental education policy, the project supports a focus on environmental learning in the context of the OBE curriculum, and provides professional development support to teachers implementing the project (NEEP, 2000). An action research evaluation is taking place to monitor key aspects of the project and a number of interim evaluation reports have been produced (Mbanjwa, 2001).
- Full Text:
- Date Issued: 2001
Adoption and use of a learning management system at the University of Fort Hare: environmental factors
- Authors: Xazela, M W H M
- Date: 2010-12
- Subjects: Management information systems , Technology -- Management
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25851 , vital:64498
- Description: Learning Management Systems are adopted and used by institutions of higher learning such as universities, universities of technology and colleges. The acceptance of integrating Learning Management Systems into the traditional classroom method of teaching and learning presents many challenges to academic staff, students, and management at various levels. If such challenges are not addressed they may lead to project failure. If such projects fail, institutions may not realise the returns on their investments as institutions usually allocate many of their resources to start such projects. This study addresses the question of which critical environmental and management success factors are necessary for the successful acceptance of such a technology and what is necessary for such a technology to be used continually. This study examines Information Systems literature, users‘ environmental and management factors, and perceptions in the context of an institution of higher learning to suggest Critical Success Factors for such a project. Critical Success Factors are identified and discussed under the contexts of Management Support, the appointment of a Project Champion, provision of training to project participants, provision of adequate access to computing resources, monitoring and evaluation of the project, the existence of strong communication channels, and creation of positive perceptions about the target technology. Acceptance models such as Technology Acceptance Model and the Expectation Confirmation Model in Information Systems literature are also taken into consideration in coming up with the suggested Critical Success Factors. , Thesis (MA) -- Faculty of Management and Commerce, 2010
- Full Text:
- Date Issued: 2010-12
- Authors: Xazela, M W H M
- Date: 2010-12
- Subjects: Management information systems , Technology -- Management
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25851 , vital:64498
- Description: Learning Management Systems are adopted and used by institutions of higher learning such as universities, universities of technology and colleges. The acceptance of integrating Learning Management Systems into the traditional classroom method of teaching and learning presents many challenges to academic staff, students, and management at various levels. If such challenges are not addressed they may lead to project failure. If such projects fail, institutions may not realise the returns on their investments as institutions usually allocate many of their resources to start such projects. This study addresses the question of which critical environmental and management success factors are necessary for the successful acceptance of such a technology and what is necessary for such a technology to be used continually. This study examines Information Systems literature, users‘ environmental and management factors, and perceptions in the context of an institution of higher learning to suggest Critical Success Factors for such a project. Critical Success Factors are identified and discussed under the contexts of Management Support, the appointment of a Project Champion, provision of training to project participants, provision of adequate access to computing resources, monitoring and evaluation of the project, the existence of strong communication channels, and creation of positive perceptions about the target technology. Acceptance models such as Technology Acceptance Model and the Expectation Confirmation Model in Information Systems literature are also taken into consideration in coming up with the suggested Critical Success Factors. , Thesis (MA) -- Faculty of Management and Commerce, 2010
- Full Text:
- Date Issued: 2010-12
Photodynamic antimicrobial chemotherapy activity of gallium tetra-(4-carboxyphenyl) porphyrin when conjugated to differently shaped platinum nanoparticles
- Managa, Muthumuni, Nyokong, Tebello
- Authors: Managa, Muthumuni , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189088 , vital:44815 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.06.077"
- Description: This work reports on the conjugation of differently shaped Pt nanoparticles (PtNPs) with ClGa(III) 5,10,15,20-tetrakis-(4-carboxyphenyl) porphyrin (ClGaTCPP). The resulting conjugates were used for photodynamic antimicrobial chemotherapy against Staphylococcus aureus. The degree of photoinactivation is dependent on concentration of the conjugates, light dose (fluence) and illumination time. The log reduction obtained for ClGaTCPP when conjugated to cubic PtNPs was 4.64 log (which indicate 99.99% of the bacteria have been killed), which is much higher than 3.94 log unit for ClGaTCPPHexagonal PtNPs and 3.31 log units for ClGaTCPP-Unshaped PtNPs. ClGaTCPP alone gave a log unit reduction of less than 3, showing the importance of conjugation to PtNPs.
- Full Text:
- Date Issued: 2015
- Authors: Managa, Muthumuni , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189088 , vital:44815 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.06.077"
- Description: This work reports on the conjugation of differently shaped Pt nanoparticles (PtNPs) with ClGa(III) 5,10,15,20-tetrakis-(4-carboxyphenyl) porphyrin (ClGaTCPP). The resulting conjugates were used for photodynamic antimicrobial chemotherapy against Staphylococcus aureus. The degree of photoinactivation is dependent on concentration of the conjugates, light dose (fluence) and illumination time. The log reduction obtained for ClGaTCPP when conjugated to cubic PtNPs was 4.64 log (which indicate 99.99% of the bacteria have been killed), which is much higher than 3.94 log unit for ClGaTCPPHexagonal PtNPs and 3.31 log units for ClGaTCPP-Unshaped PtNPs. ClGaTCPP alone gave a log unit reduction of less than 3, showing the importance of conjugation to PtNPs.
- Full Text:
- Date Issued: 2015
Optical nonlinearities and photophysicochemical behaviour of green and blue forms of lutetium bisphthalocyanines
- Sekhosana, Kutloana Edith, Amuhaya, Edith, Mack, John, Nyokong, Tebello
- Authors: Sekhosana, Kutloana Edith , Amuhaya, Edith , Mack, John , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241606 , vital:50954 , xlink:href="https://doi.org/10.1039/C4TC00505H"
- Description: A rare earth sandwich-type phthalocyanine: bis-{2,3,9,10,16,17,23,24-octa(4-tert-butylphenoxy) phthalocyaninato} lutetium(III) has been synthesized. The photophysical and nonlinear optical behavior of both the “green” and “blue” forms ([LuIIIPc2] and [LuIIIPc2]−, respectively) of the complex have been investigated. High triplet state and singlet oxygen quantum yield values were obtained for the neutral blue form which contains no unpaired electrons. Relatively high third order susceptibility and hyperpolarizability values of the order of 10−10 and 10−28 esu were obtained for both the green and blue forms, respectively. A very low threshold intensity of 0.00051 J cm−2 was obtained for the blue form. Hence the complex shows promise for non-linear optical applications.
- Full Text:
- Date Issued: 2014
- Authors: Sekhosana, Kutloana Edith , Amuhaya, Edith , Mack, John , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241606 , vital:50954 , xlink:href="https://doi.org/10.1039/C4TC00505H"
- Description: A rare earth sandwich-type phthalocyanine: bis-{2,3,9,10,16,17,23,24-octa(4-tert-butylphenoxy) phthalocyaninato} lutetium(III) has been synthesized. The photophysical and nonlinear optical behavior of both the “green” and “blue” forms ([LuIIIPc2] and [LuIIIPc2]−, respectively) of the complex have been investigated. High triplet state and singlet oxygen quantum yield values were obtained for the neutral blue form which contains no unpaired electrons. Relatively high third order susceptibility and hyperpolarizability values of the order of 10−10 and 10−28 esu were obtained for both the green and blue forms, respectively. A very low threshold intensity of 0.00051 J cm−2 was obtained for the blue form. Hence the complex shows promise for non-linear optical applications.
- Full Text:
- Date Issued: 2014
Photophysical behavior of zinc monoaminophthalocyanines linked to mercaptopropionic acid-capped CdTe quantum dots
- D'Souza, Sarah, Antunes, Edith M, Litwinski, Christian, Nyokong, Tebello
- Authors: D'Souza, Sarah , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247634 , vital:51602 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.03.005"
- Description: Photosensitizing properties of zinc monoaminophthalocyanine (2) {in the absence or presence of mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs)} were compared with those of mono-aminophenoxy zinc phthalocyanine (3), zinc tetrasulfonated phthalocyanine and zinc phthalocyanine. Complexes 2 and 3 were also linked to the MPA capped CdTe quantum dots through the formation of an amide bond. High triplet state quantum yields were obtained for the linked QD–phthalocyanine derivatives (complexes 2 and 3) compared to when complexes 2 and 3 were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
- Authors: D'Souza, Sarah , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247634 , vital:51602 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.03.005"
- Description: Photosensitizing properties of zinc monoaminophthalocyanine (2) {in the absence or presence of mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs)} were compared with those of mono-aminophenoxy zinc phthalocyanine (3), zinc tetrasulfonated phthalocyanine and zinc phthalocyanine. Complexes 2 and 3 were also linked to the MPA capped CdTe quantum dots through the formation of an amide bond. High triplet state quantum yields were obtained for the linked QD–phthalocyanine derivatives (complexes 2 and 3) compared to when complexes 2 and 3 were mixed with MPA QDs without a chemical bond.
- Full Text:
- Date Issued: 2011
Assessment of cytotoxic artemisinin and its derivatives as DNA damaging inducing agents in triple-negative breast cancer cells
- Authors: Mkhwanazi, Ntando
- Date: 2022-10-14
- Subjects: Breast Cancer , Artemisinin , DNA damage , Antineoplastic agents , Breast Cancer Treatment
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/362960 , vital:65378
- Description: In developing countries, including South Africa, breast cancer is the primary cause of cancer-related deaths among women. TNBC (triple-negative breast cancer) is an aggressive breast cancer subtype that is more prevalent in women of African descent. This subtype lacks the key receptors, namely the estrogen receptor (ER-), progesterone receptor (PR-), and human epidermal growth factor receptor 2 (HER2-) that are the basis of successful targeted therapies for other subtypes of the disease. To date, there are no effective, standardized targeted therapies for TNBC. Artemisinin is an anti-malarial drug and numerous derivatives of the compound have been developed to improve the potency and solubility of the parent compound. Artemisinin and its derivatives have gained attention as potential anti-cancer agents; however, such studies have not yet progressed to clinical trials and the precise mechanism of action of these compounds is yet to be fully explained. In this study, artemisinin, and its known derivative artesunate, as well as a novel derivative, WHN11, were investigated as DNA damage-inducing agents in TNBC. WHN11 was found to be the most potent of the three compounds, displaying an IC50 of 3.20 μM against HCC70 cells, artemisinin displayed an IC50 of 214.70 μM and artesunate displayed an IC50 of 25.48 μM. The compounds were less toxic to the MCF12A non-cancerous cells, with IC50 values 298.30, 87.53, and 8.35 μM for artemisinin, artesunate, and WHN11, respectively, and displayed selectivity indices of 1.39, 3.44 and 2.61 μM for artemisinin, artesunate, and WHN11, respectively. In silico and in vitro studies revealed that the artemisinin compounds bind to DNA through the minor groove. While all three compounds were able to bind to DNA, a comet assay revealed that only artemisinin and artesunate, and not WHN11, were able to cause DNA damage compared to the vehicle control, DMSO. Finally, a topoisomerase I (TOPO I) enzyme assay demonstrated that while the compounds appeared to display a degree of inhibition of TOPO I, as evidenced by a downward shift in the plasmid band on the agarose gel, they were not able to fully inhibit the enzyme to return the plasmid to the supercoiled conformation. In addition, combination studies revealed that artemisinin, artesunate, and WHN11 acted synergistically in combination with camptothecin, but displayed either an additive (artemisinin) or antagonistic (artesunate and WHN11) relationship when used in combination with etoposide. In conclusion, artemisinin, its known derivative artesunate, and novel and highly toxic derivative WHN11, all bind to DNA via the minor groove, however only artemisinin and artesunate, and not WHN11, cause DNA damage, indicating a potentially different mechanism of action of the three artemisinins. All three compounds act synergistically with camptothecin, which suggests interference with topoisomerase activity, partially supported by slight inhibition of TOPO I activity, and could indicate either direct inhibition of the enzyme or interference with enzyme function by competitive binding to the DNA. Further studies could help explore alternate DNA damage assays, to validate these findings, and the effect of the compounds on TOPO II activity could also be assessed. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-10-14
- Authors: Mkhwanazi, Ntando
- Date: 2022-10-14
- Subjects: Breast Cancer , Artemisinin , DNA damage , Antineoplastic agents , Breast Cancer Treatment
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/362960 , vital:65378
- Description: In developing countries, including South Africa, breast cancer is the primary cause of cancer-related deaths among women. TNBC (triple-negative breast cancer) is an aggressive breast cancer subtype that is more prevalent in women of African descent. This subtype lacks the key receptors, namely the estrogen receptor (ER-), progesterone receptor (PR-), and human epidermal growth factor receptor 2 (HER2-) that are the basis of successful targeted therapies for other subtypes of the disease. To date, there are no effective, standardized targeted therapies for TNBC. Artemisinin is an anti-malarial drug and numerous derivatives of the compound have been developed to improve the potency and solubility of the parent compound. Artemisinin and its derivatives have gained attention as potential anti-cancer agents; however, such studies have not yet progressed to clinical trials and the precise mechanism of action of these compounds is yet to be fully explained. In this study, artemisinin, and its known derivative artesunate, as well as a novel derivative, WHN11, were investigated as DNA damage-inducing agents in TNBC. WHN11 was found to be the most potent of the three compounds, displaying an IC50 of 3.20 μM against HCC70 cells, artemisinin displayed an IC50 of 214.70 μM and artesunate displayed an IC50 of 25.48 μM. The compounds were less toxic to the MCF12A non-cancerous cells, with IC50 values 298.30, 87.53, and 8.35 μM for artemisinin, artesunate, and WHN11, respectively, and displayed selectivity indices of 1.39, 3.44 and 2.61 μM for artemisinin, artesunate, and WHN11, respectively. In silico and in vitro studies revealed that the artemisinin compounds bind to DNA through the minor groove. While all three compounds were able to bind to DNA, a comet assay revealed that only artemisinin and artesunate, and not WHN11, were able to cause DNA damage compared to the vehicle control, DMSO. Finally, a topoisomerase I (TOPO I) enzyme assay demonstrated that while the compounds appeared to display a degree of inhibition of TOPO I, as evidenced by a downward shift in the plasmid band on the agarose gel, they were not able to fully inhibit the enzyme to return the plasmid to the supercoiled conformation. In addition, combination studies revealed that artemisinin, artesunate, and WHN11 acted synergistically in combination with camptothecin, but displayed either an additive (artemisinin) or antagonistic (artesunate and WHN11) relationship when used in combination with etoposide. In conclusion, artemisinin, its known derivative artesunate, and novel and highly toxic derivative WHN11, all bind to DNA via the minor groove, however only artemisinin and artesunate, and not WHN11, cause DNA damage, indicating a potentially different mechanism of action of the three artemisinins. All three compounds act synergistically with camptothecin, which suggests interference with topoisomerase activity, partially supported by slight inhibition of TOPO I activity, and could indicate either direct inhibition of the enzyme or interference with enzyme function by competitive binding to the DNA. Further studies could help explore alternate DNA damage assays, to validate these findings, and the effect of the compounds on TOPO II activity could also be assessed. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-10-14
Bioinformatic analysis of Aminoacyl tRNA Synthetases as potential antimalarial drug targets
- Authors: Nyamai, Dorothy Wavinya
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164579 , vital:41142 , doi:10.21504/10962/164579
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Date Issued: 2020
- Authors: Nyamai, Dorothy Wavinya
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164579 , vital:41142 , doi:10.21504/10962/164579
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Date Issued: 2020
Secularization processes in Malawi and Great Britain: a comparative inquiry
- Authors: Gama, Billy Lickson
- Date: 2013-12
- Subjects: Secularization (Theology)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/25644 , vital:64346
- Description: The major purpose of the study was to critically examine the applicability of manifestations and factors of secularization in Britain to Malawi. In examining the manifestations and factors the study had to examine the process of secularization in Britain and its causal factors using theoretical frameworks and examine manifestations and causal factors of secularization in Malawi using field research work as a major source supported by the theoretical frame works of secularization. The study was guided by the key research question, “Are the manifestations and factors of secularization in Britain applicable to Malawi?” The question was supported by other follow up questions, namely, “What were the factors that contributed to the rise of secularization in Britain?” “What is the connection between Britain and Malawi?” “To what extent does secularization in Britain affect that in Malawi?” “Does Malawi have unique factors that are specific or are the same factors at work that have contributed to the process of secularization in Britain?” The conceptual framework for this research was derived from the literature on “secularization” from different scholars, in particular, the work of Dobbelaere (2002) whose analysis of secularization provided the theoretical frame work for this study. Learning from Dobbelaere (2002) the study used three types of secularizations, namely, societal, organizational and individual. Dobbelaere (2002:24ff) distinguishes the three types of secularization in a very simple way: individual secularization, the lack of individual practice, societal secularization, the loss of influence on society, and organizational secularization as the effect on religious organizations by changes in society. The methodological approach to the study was the mixed methods approach that involved three types of research methodologies: the qualitative, quantitative and case studies approaches. Data was collected through personal and focus group interviews. It was supported by secondary sources which include books, minutes of meetings in various institutions and the internet. The study notes that all the three types of secularization are being experienced in Malawi; societal secularization has been manifested by the removal of religious connected syllabus in schools, suspension of homosexuality laws and involvement of religious leaders in different immoral issues just like non-believers. Organizational secularization has been manifested by fights among religious institutions e.g. boarder disputes that have been given as case studies in chapter five and finally the individual secularization is being manifested in Malawi as membership records indicate that there is a big decline in church attendance and participation in religious activities. New knowledge that this study is proposing is that secularization is manifested in Malawi through the partial influence from Britain because of strong links between the two countries and the effects of modernization. The study further proposes that donor influences, Islam, lack of well educated religious leaders and African Traditional Religion are the unique factors of secularization in Malawi, while modernization, urbanization, industrialization are factors that are partially applicable to Malawi, and religious pluralism is fully applicable to both Britain and Malawi as a factor of secularization. Finally the study proposes that a proper training of religious leaders is vital for the sustainability of the church as it experiences the manifestations of secularization. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2013
- Full Text:
- Date Issued: 2013-12
- Authors: Gama, Billy Lickson
- Date: 2013-12
- Subjects: Secularization (Theology)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/25644 , vital:64346
- Description: The major purpose of the study was to critically examine the applicability of manifestations and factors of secularization in Britain to Malawi. In examining the manifestations and factors the study had to examine the process of secularization in Britain and its causal factors using theoretical frameworks and examine manifestations and causal factors of secularization in Malawi using field research work as a major source supported by the theoretical frame works of secularization. The study was guided by the key research question, “Are the manifestations and factors of secularization in Britain applicable to Malawi?” The question was supported by other follow up questions, namely, “What were the factors that contributed to the rise of secularization in Britain?” “What is the connection between Britain and Malawi?” “To what extent does secularization in Britain affect that in Malawi?” “Does Malawi have unique factors that are specific or are the same factors at work that have contributed to the process of secularization in Britain?” The conceptual framework for this research was derived from the literature on “secularization” from different scholars, in particular, the work of Dobbelaere (2002) whose analysis of secularization provided the theoretical frame work for this study. Learning from Dobbelaere (2002) the study used three types of secularizations, namely, societal, organizational and individual. Dobbelaere (2002:24ff) distinguishes the three types of secularization in a very simple way: individual secularization, the lack of individual practice, societal secularization, the loss of influence on society, and organizational secularization as the effect on religious organizations by changes in society. The methodological approach to the study was the mixed methods approach that involved three types of research methodologies: the qualitative, quantitative and case studies approaches. Data was collected through personal and focus group interviews. It was supported by secondary sources which include books, minutes of meetings in various institutions and the internet. The study notes that all the three types of secularization are being experienced in Malawi; societal secularization has been manifested by the removal of religious connected syllabus in schools, suspension of homosexuality laws and involvement of religious leaders in different immoral issues just like non-believers. Organizational secularization has been manifested by fights among religious institutions e.g. boarder disputes that have been given as case studies in chapter five and finally the individual secularization is being manifested in Malawi as membership records indicate that there is a big decline in church attendance and participation in religious activities. New knowledge that this study is proposing is that secularization is manifested in Malawi through the partial influence from Britain because of strong links between the two countries and the effects of modernization. The study further proposes that donor influences, Islam, lack of well educated religious leaders and African Traditional Religion are the unique factors of secularization in Malawi, while modernization, urbanization, industrialization are factors that are partially applicable to Malawi, and religious pluralism is fully applicable to both Britain and Malawi as a factor of secularization. Finally the study proposes that a proper training of religious leaders is vital for the sustainability of the church as it experiences the manifestations of secularization. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2013
- Full Text:
- Date Issued: 2013-12
Enhanced mitochondria destruction on MCF-7 and HeLa cell lines in vitro using triphenyl-phosphonium-labelled phthalocyanines in ultrasound-assisted photodynamic therapy activity
- Nene, Lindokuhle Cindy, Magadla, Aviwe, Nyokong, Tebello
- Authors: Nene, Lindokuhle Cindy , Magadla, Aviwe , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295766 , vital:57376 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2022.112553"
- Description: This work reports on the reactive oxygen species (ROS) generation and the therapeutic activities of new triphenyl-phosphonium-labelled phthalocyanines (Pcs), the 2,9,16,23-tetrakis(N-(N-butyl-4-triphenyl-phosphonium)- pyridine-4-yloxy) Zn(II) Pc (3) and 2,9,16,23-tetrakis-(N-(N-butyl-4-triphenyl-phosphonium)-morpholino) Zn(II) Pc (4) upon exposure to light, ultrasound and the combination of light and ultrasound. Two types of ROS were detected: the singlet oxygen (1O2) and hydroxyl radicals. For light irradiations, only the 1O2 was detected. An increase in the ROS generation was observed for samples treated with the combination of light and ultrasound compared to the light and ultrasound mono-treatments. The in vitro anticancer activity through photodynamic (PDT) and sonodynamic (SDT) therapy for the Pcs were also determined and compared to the photo-sonodynamic combination therapy (PSDT). The two cancer cell lines used for the in vitro studies included the Michigan Cancer Foundation-7 (MCF-7) breast cancer and Henrietta Lacks (HeLa) cervical cancer cell lines. The SDT treatments showed improved therapeutic efficacy on the cancer cells for both the Pcs compared to PDT. PSDT showed better therapeutic efficacy compared to both the PDT and SDT mono-treatments.
- Full Text:
- Date Issued: 2022
- Authors: Nene, Lindokuhle Cindy , Magadla, Aviwe , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295766 , vital:57376 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2022.112553"
- Description: This work reports on the reactive oxygen species (ROS) generation and the therapeutic activities of new triphenyl-phosphonium-labelled phthalocyanines (Pcs), the 2,9,16,23-tetrakis(N-(N-butyl-4-triphenyl-phosphonium)- pyridine-4-yloxy) Zn(II) Pc (3) and 2,9,16,23-tetrakis-(N-(N-butyl-4-triphenyl-phosphonium)-morpholino) Zn(II) Pc (4) upon exposure to light, ultrasound and the combination of light and ultrasound. Two types of ROS were detected: the singlet oxygen (1O2) and hydroxyl radicals. For light irradiations, only the 1O2 was detected. An increase in the ROS generation was observed for samples treated with the combination of light and ultrasound compared to the light and ultrasound mono-treatments. The in vitro anticancer activity through photodynamic (PDT) and sonodynamic (SDT) therapy for the Pcs were also determined and compared to the photo-sonodynamic combination therapy (PSDT). The two cancer cell lines used for the in vitro studies included the Michigan Cancer Foundation-7 (MCF-7) breast cancer and Henrietta Lacks (HeLa) cervical cancer cell lines. The SDT treatments showed improved therapeutic efficacy on the cancer cells for both the Pcs compared to PDT. PSDT showed better therapeutic efficacy compared to both the PDT and SDT mono-treatments.
- Full Text:
- Date Issued: 2022
State antiquity and early agricultural transition as deep economic roots in Africa
- Authors: Fani, Sisipho
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55487 , vital:52374
- Description: Growth economists identified that current failures and successes of economies can be traced far in their histories. The Unified Growth Model has been developed to analyse the process of development. Economic researchers have developed and identified ‘deep roots’ variables that elaborate modern growth, institutions and development. These variables include State Antiquity and Early agricultural transition. The study is an examination of the effects of State Antiquity and Early agricultural transition in the 54 African economies. The study examines these effects employing the following years: 1990, 1995, 2000, 2005, 2010, 2015, and 2020. The study employs econometric models namely, Ordinary Least Squares, Ridge and Lasso regularization models to examine the effects of these deep root variables. The study borrows baseline regressions from the works of Bockstette, Chanda and Putterman (2002), Putterman and Weil (2010) and Borcan, Olsson and Putterman (2018). This study, to the best of our knowledge, is the first to empirically examine the effects of State Antiquity and Early agricultural transition in Africa. The results of the study suggest that African economies that have low level of state antiquity experience a positive effect on modern economic growth and development whilst African economies with high levels of state antiquity experience negative effect on modern economic growth and development. The results also suggest that African economies that transition at a later stage toward agriculture experience a positive effect on modern economic growth and development. The implications of these findings indicate that state antiquity and early agricultural transition influence modern economic development only when states have reached a certain level. Countries that transitioned early towards agriculture experience a negative effect on modern economic growth and development depicting a reversal of fortune. The study recommends that the implementation of polices should corelate with the state experience of the specific economy. , Thesis (M.Com.) -- Faculty of Business and Economic Sciences, School of Economics, Development & Tourism, 2022
- Full Text:
- Authors: Fani, Sisipho
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55487 , vital:52374
- Description: Growth economists identified that current failures and successes of economies can be traced far in their histories. The Unified Growth Model has been developed to analyse the process of development. Economic researchers have developed and identified ‘deep roots’ variables that elaborate modern growth, institutions and development. These variables include State Antiquity and Early agricultural transition. The study is an examination of the effects of State Antiquity and Early agricultural transition in the 54 African economies. The study examines these effects employing the following years: 1990, 1995, 2000, 2005, 2010, 2015, and 2020. The study employs econometric models namely, Ordinary Least Squares, Ridge and Lasso regularization models to examine the effects of these deep root variables. The study borrows baseline regressions from the works of Bockstette, Chanda and Putterman (2002), Putterman and Weil (2010) and Borcan, Olsson and Putterman (2018). This study, to the best of our knowledge, is the first to empirically examine the effects of State Antiquity and Early agricultural transition in Africa. The results of the study suggest that African economies that have low level of state antiquity experience a positive effect on modern economic growth and development whilst African economies with high levels of state antiquity experience negative effect on modern economic growth and development. The results also suggest that African economies that transition at a later stage toward agriculture experience a positive effect on modern economic growth and development. The implications of these findings indicate that state antiquity and early agricultural transition influence modern economic development only when states have reached a certain level. Countries that transitioned early towards agriculture experience a negative effect on modern economic growth and development depicting a reversal of fortune. The study recommends that the implementation of polices should corelate with the state experience of the specific economy. , Thesis (M.Com.) -- Faculty of Business and Economic Sciences, School of Economics, Development & Tourism, 2022
- Full Text:
Detonation nanodiamonds-phthalocyanine photosensitizers with enhanced photophysicochemical properties and effective photoantibacterial activity
- Openda, Yolande I, Nyokong, Tebello
- Authors: Openda, Yolande I , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186012 , vital:44455 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102072"
- Description: The nanophotosensitizers based on acetophenoxy tetrasubstituted metallophthalocyanines (MPc) and detonation nanodiamonds (DNDs) were successfully formed and their photophysicochemical properties were determined. The zinc(II)Pc and indium(III)Pc complexes along with their nanoconjugates were found to have high singlet oxygen quantum yields (0.72 − 0.84) associated with the heavy central metal effect. The ability of the functional groups present on the DNDs to bind to the bacteria cell and the improved solubility of the nanoconjugates due to DNDs resulted in effective photodynamic antimicrobial therapy (PACT) activity against S. aureus planktonic cells, with the highest log reduction of 9.72 ± 0.02 for the conjugate of InPc conjugate with DNDs after 30 min irradiation. PACT studies were investigated at a dose of 10 μg/mL for each sample. The results suggest that the readily synthesized nanoconjugates can be used as appropriate PACT agents.
- Full Text:
- Date Issued: 2020
- Authors: Openda, Yolande I , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186012 , vital:44455 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102072"
- Description: The nanophotosensitizers based on acetophenoxy tetrasubstituted metallophthalocyanines (MPc) and detonation nanodiamonds (DNDs) were successfully formed and their photophysicochemical properties were determined. The zinc(II)Pc and indium(III)Pc complexes along with their nanoconjugates were found to have high singlet oxygen quantum yields (0.72 − 0.84) associated with the heavy central metal effect. The ability of the functional groups present on the DNDs to bind to the bacteria cell and the improved solubility of the nanoconjugates due to DNDs resulted in effective photodynamic antimicrobial therapy (PACT) activity against S. aureus planktonic cells, with the highest log reduction of 9.72 ± 0.02 for the conjugate of InPc conjugate with DNDs after 30 min irradiation. PACT studies were investigated at a dose of 10 μg/mL for each sample. The results suggest that the readily synthesized nanoconjugates can be used as appropriate PACT agents.
- Full Text:
- Date Issued: 2020