Synthesis, characterization and antibacterial studies of metal complexes of substituted thiourea
- Authors: Zulu, Happy Nonkululeko
- Date: 2012-03
- Subjects: Complex compounds , Halides , Ligands
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24327 , vital:62636
- Description: Eighteen complexes Co(II), Cu(II), Zn(II), and Fe(III) with phenylthiourea, diethylthiourea, disopropylthiourea and dimethylthiourea were synthesized and characterized by elemental analysis, UV-Vis, FTIR, conductivity measurements. The complexes were formulated as either four coordinate for the metal(II) or six coordinate for Fe(III). The proposed formulations are consistent with the spectroscopic data for the complexes. The single crystal X-ray structure of the Zn(II) complex of phenylthiourea, Co(II) complex of diethylthiourea and Zn(II) complex of diisopropylthiourea are also reported. The X-ray crystal structures for these complexes revealed distorted tetrahedral geometry around the metal ions showed that the metal ions are coordinated to two molecules of the substituted thiourea through the sulphur atom and two either acetates or chlorides ions complete the four-coordinate geometry. The in vitro antibacterial activity of the complexes was studied against six bacterial strains using disc diffusion and broth micro-dilution methods. The complexes showed selective antibacterial activity. , Thesis (MSc) -- Faculty of Science and Agriculture, 2012
- Full Text:
- Date Issued: 2012-03
- Authors: Zulu, Happy Nonkululeko
- Date: 2012-03
- Subjects: Complex compounds , Halides , Ligands
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24327 , vital:62636
- Description: Eighteen complexes Co(II), Cu(II), Zn(II), and Fe(III) with phenylthiourea, diethylthiourea, disopropylthiourea and dimethylthiourea were synthesized and characterized by elemental analysis, UV-Vis, FTIR, conductivity measurements. The complexes were formulated as either four coordinate for the metal(II) or six coordinate for Fe(III). The proposed formulations are consistent with the spectroscopic data for the complexes. The single crystal X-ray structure of the Zn(II) complex of phenylthiourea, Co(II) complex of diethylthiourea and Zn(II) complex of diisopropylthiourea are also reported. The X-ray crystal structures for these complexes revealed distorted tetrahedral geometry around the metal ions showed that the metal ions are coordinated to two molecules of the substituted thiourea through the sulphur atom and two either acetates or chlorides ions complete the four-coordinate geometry. The in vitro antibacterial activity of the complexes was studied against six bacterial strains using disc diffusion and broth micro-dilution methods. The complexes showed selective antibacterial activity. , Thesis (MSc) -- Faculty of Science and Agriculture, 2012
- Full Text:
- Date Issued: 2012-03
Synthesis, characterization and antiparasitic evaluation of chalcone hybrids
- Authors: Zulu, Ayanda Ignatia
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192853 , vital:45271
- Description: Thesis (PhD) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Zulu, Ayanda Ignatia
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192853 , vital:45271
- Description: Thesis (PhD) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
Synthesis and evaluation of arylpyrrole-chalcone hybrids as antiplasmodial and antitrypanosomal agents
- Authors: Zulu, Ayanda Ignatia
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65268 , vital:28716
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2017
- Authors: Zulu, Ayanda Ignatia
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/65268 , vital:28716
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2017
Synthesis, structure and in vitro anti-trypanosomal activity of non-toxic Arylpyrrole-Based Chalcone derivatives:
- Zulu, Ayanda I, Oderinlo, Ogunyemi O, Kruger, Cuan, Isaacs, Michelle, Hoppe, Heinrich C, Smith, Vincent J, Veale, Clinton G L, Khanye, Setshaba D
- Authors: Zulu, Ayanda I , Oderinlo, Ogunyemi O , Kruger, Cuan , Isaacs, Michelle , Hoppe, Heinrich C , Smith, Vincent J , Veale, Clinton G L , Khanye, Setshaba D
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179017 , vital:40096 , https://doi.org/10.3390/molecules25071668
- Description: With an intention of identifying chalcone derivatives exhibiting anti-protozoal activity, a cohort of relatively unexplored arylpyrrole-based chalcone derivatives were synthesized in moderate to good yields. The resultant compounds were evaluated in vitro for their potential activity against a cultured Trypanosoma brucei brucei 427 strain. Several compounds displayed mostly modest in vitro anti-trypanosomal activity with compounds 10e and 10h emerging as active candidates with IC50 values of 4.09 and 5.11 µM, respectively. More importantly, a concomitant assessment of their activity against a human cervix adenocarcinoma (HeLa) cell line revealed that these compounds are non-toxic.
- Full Text:
- Date Issued: 2020
- Authors: Zulu, Ayanda I , Oderinlo, Ogunyemi O , Kruger, Cuan , Isaacs, Michelle , Hoppe, Heinrich C , Smith, Vincent J , Veale, Clinton G L , Khanye, Setshaba D
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179017 , vital:40096 , https://doi.org/10.3390/molecules25071668
- Description: With an intention of identifying chalcone derivatives exhibiting anti-protozoal activity, a cohort of relatively unexplored arylpyrrole-based chalcone derivatives were synthesized in moderate to good yields. The resultant compounds were evaluated in vitro for their potential activity against a cultured Trypanosoma brucei brucei 427 strain. Several compounds displayed mostly modest in vitro anti-trypanosomal activity with compounds 10e and 10h emerging as active candidates with IC50 values of 4.09 and 5.11 µM, respectively. More importantly, a concomitant assessment of their activity against a human cervix adenocarcinoma (HeLa) cell line revealed that these compounds are non-toxic.
- Full Text:
- Date Issued: 2020
Perceptions of Kwazulu-Natal radiographers regarding the role of professional development in clinical practice
- Authors: Zulu Anelisa
- Date: 2022-12
- Subjects: Radiography -- KwaZulu Natal , radiographers regarding
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60290 , vital:64292
- Description: Professional development in the form of continuing education is associated with professional competence and good service delivery to the patient, and this understanding of professional development applies to the radiography profession. A manager may prompt participation in professional development, or the needs of a radiography department may influence it, or it may be driven by the personal and professional ambitions of the radiographer. Participation could also be due to regulatory body requirements, which require tracking and documentation as in the case of the Health Professions Council of South Africa (HPCSA) which may audit the professional’s continuing professional development (CPD) compliance. Professional development is a concept inclusive of all learning such as CPD; postgraduate qualifications; staff development; and reflective practice, pursued for the betterment of the radiographers’ professional expertise. Few if any qualitative studies have sought to explore South African radiographers’ perceptions of professional development as a concept inclusive of all learning. The purpose of the study was to explore and describe the perceptions of KwaZulu-Natal radiographers regarding the role of professional development in clinical practice to make recommendations to radiography managers on how to optimise the participation of radiographers in professional development. Bandura’s social learning theory was used as the theoretical framework for a study of the perceptions of practising KZN radiographers regarding the role of professional development in clinical practice and exploring how people learn from one another, including concepts such as observational learning, imitation, and modelling. The target population for the study consisted of practising radiographers working in the public and private, rural and urban hospitals in KZN. Data were gathered using semi-structured one-on-one interviews and were coded using Tesch’s eight steps. The trustworthiness of this study was enhanced using Lincoln and Guba’s (1985) model of trustworthiness, namely: credibility, transferability, dependability and confirmability. , Thesis (MA) -- Faculty of Health Sciences, 2022
- Full Text:
- Date Issued: 2022-12
- Authors: Zulu Anelisa
- Date: 2022-12
- Subjects: Radiography -- KwaZulu Natal , radiographers regarding
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60290 , vital:64292
- Description: Professional development in the form of continuing education is associated with professional competence and good service delivery to the patient, and this understanding of professional development applies to the radiography profession. A manager may prompt participation in professional development, or the needs of a radiography department may influence it, or it may be driven by the personal and professional ambitions of the radiographer. Participation could also be due to regulatory body requirements, which require tracking and documentation as in the case of the Health Professions Council of South Africa (HPCSA) which may audit the professional’s continuing professional development (CPD) compliance. Professional development is a concept inclusive of all learning such as CPD; postgraduate qualifications; staff development; and reflective practice, pursued for the betterment of the radiographers’ professional expertise. Few if any qualitative studies have sought to explore South African radiographers’ perceptions of professional development as a concept inclusive of all learning. The purpose of the study was to explore and describe the perceptions of KwaZulu-Natal radiographers regarding the role of professional development in clinical practice to make recommendations to radiography managers on how to optimise the participation of radiographers in professional development. Bandura’s social learning theory was used as the theoretical framework for a study of the perceptions of practising KZN radiographers regarding the role of professional development in clinical practice and exploring how people learn from one another, including concepts such as observational learning, imitation, and modelling. The target population for the study consisted of practising radiographers working in the public and private, rural and urban hospitals in KZN. Data were gathered using semi-structured one-on-one interviews and were coded using Tesch’s eight steps. The trustworthiness of this study was enhanced using Lincoln and Guba’s (1985) model of trustworthiness, namely: credibility, transferability, dependability and confirmability. , Thesis (MA) -- Faculty of Health Sciences, 2022
- Full Text:
- Date Issued: 2022-12
The nexus between capital inflows, financial sector development and domestic investment in selected southern African development community countries
- Zulani, Sihle https://orcid.org/0009-0006-7067-5793
- Authors: Zulani, Sihle https://orcid.org/0009-0006-7067-5793
- Date: 2023-03
- Subjects: Capital movements -- Africa, Southern , Saving and investment -- Africa, Southern , Financial services industry -- Africa, Southern
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/28872 , vital:75154
- Description: The study seeks to examine the nexus between foreign capital inflows as proxied by foreign direct investment and overseas development assistance, financial sector development as measured by domestic credit to private sector and broad money supply (M3) and domestic investment [gross fixed capital formation] in selected Southern African Development Community (SADC) countries. Panel data model, specifically the panel Autoregressive Distributed Lag technique given the order of integration of the variables utilised in the study was employed from 1980 to 2019. The results revealed that there is cointegration among the variables utilised. After confirming cointegration, the long-run and short run models were estimated to establish the relationship between the variables. The long-run results revealed that about 67% of domestic investment in the SADC region is generated through foreign direct investment. These results suggest that domestic investment is boosted by foreign direct investment in the SADC region. However, financial sector development was found to have a negative effect on domestic investment in the SADC region. The findings from this study suggest that countries should pursue policies aimed at attracting FDI into the SADC region given the positive effect it has on investment. On the part of financial sector development, this could be attributed to the sector not supporting most of the domestic investment given that most of them are small and do not access bank finance. , Thesis (MCom) -- Faculty of Management and Commerce, 2023
- Full Text:
- Date Issued: 2023-03
- Authors: Zulani, Sihle https://orcid.org/0009-0006-7067-5793
- Date: 2023-03
- Subjects: Capital movements -- Africa, Southern , Saving and investment -- Africa, Southern , Financial services industry -- Africa, Southern
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/28872 , vital:75154
- Description: The study seeks to examine the nexus between foreign capital inflows as proxied by foreign direct investment and overseas development assistance, financial sector development as measured by domestic credit to private sector and broad money supply (M3) and domestic investment [gross fixed capital formation] in selected Southern African Development Community (SADC) countries. Panel data model, specifically the panel Autoregressive Distributed Lag technique given the order of integration of the variables utilised in the study was employed from 1980 to 2019. The results revealed that there is cointegration among the variables utilised. After confirming cointegration, the long-run and short run models were estimated to establish the relationship between the variables. The long-run results revealed that about 67% of domestic investment in the SADC region is generated through foreign direct investment. These results suggest that domestic investment is boosted by foreign direct investment in the SADC region. However, financial sector development was found to have a negative effect on domestic investment in the SADC region. The findings from this study suggest that countries should pursue policies aimed at attracting FDI into the SADC region given the positive effect it has on investment. On the part of financial sector development, this could be attributed to the sector not supporting most of the domestic investment given that most of them are small and do not access bank finance. , Thesis (MCom) -- Faculty of Management and Commerce, 2023
- Full Text:
- Date Issued: 2023-03
Factors affecting teachers' attitude towards the implementation of inclusive education
- Authors: Zukani, Ncediswa Millicent
- Date: 2018
- Subjects: Inclusive education Mainstreaming in education -- South Africa
- Language: English
- Type: Thesis , Masters , (MEd) Education
- Identifier: http://hdl.handle.net/10353/10094 , vital:35336
- Description: This study is a quantitative study done in selected schools on teachers’ attitudes towards the implementation of inclusive education. Despite efforts to ensure quality education for all learners through inclusive education in South Africa, indications are that many learners, especially those who experience barriers to learning, are still excluded from full access to quality and equitable education opportunities in mainstream schools. Research has shown that the success of inclusive education depends upon teachers’ attitudes. It also shows that attitudes can hinder the progress of the implementation of inclusive education. The paper draws on White Paper 6 which speaks to inclusion of children with disabilities in schools. As the legislative and policy framework for the implementation of inclusive education, White Paper 6 states that “a public school must admit learners and serve their educational requirements without unfairly discriminating in any way”. The study is framed by Ajzen’s theory of planned behaviour, which suggests that an attitude towards behaviour is influenced by past experiences, previous knowledge and newly acquired knowledge. The study reflects findings from a questionnaire circulated to 75 teachers at three selected high schools, using descriptive statistics to analyse the data. Findings showed that there is no relationship between attitudes based on factors, including class size, years of experience, inadequate resource, and lack of adequate training but the main negative influence was found to be lack of support in implementing inclusive education. The conclusion is that there is no relationship between attitudes and the factors identified except lack of support. This research concludes with recommendations to address teachers’ attitudes in order to facilitate the inclusion of learners with special needs in the classroom.
- Full Text:
- Date Issued: 2018
- Authors: Zukani, Ncediswa Millicent
- Date: 2018
- Subjects: Inclusive education Mainstreaming in education -- South Africa
- Language: English
- Type: Thesis , Masters , (MEd) Education
- Identifier: http://hdl.handle.net/10353/10094 , vital:35336
- Description: This study is a quantitative study done in selected schools on teachers’ attitudes towards the implementation of inclusive education. Despite efforts to ensure quality education for all learners through inclusive education in South Africa, indications are that many learners, especially those who experience barriers to learning, are still excluded from full access to quality and equitable education opportunities in mainstream schools. Research has shown that the success of inclusive education depends upon teachers’ attitudes. It also shows that attitudes can hinder the progress of the implementation of inclusive education. The paper draws on White Paper 6 which speaks to inclusion of children with disabilities in schools. As the legislative and policy framework for the implementation of inclusive education, White Paper 6 states that “a public school must admit learners and serve their educational requirements without unfairly discriminating in any way”. The study is framed by Ajzen’s theory of planned behaviour, which suggests that an attitude towards behaviour is influenced by past experiences, previous knowledge and newly acquired knowledge. The study reflects findings from a questionnaire circulated to 75 teachers at three selected high schools, using descriptive statistics to analyse the data. Findings showed that there is no relationship between attitudes based on factors, including class size, years of experience, inadequate resource, and lack of adequate training but the main negative influence was found to be lack of support in implementing inclusive education. The conclusion is that there is no relationship between attitudes and the factors identified except lack of support. This research concludes with recommendations to address teachers’ attitudes in order to facilitate the inclusion of learners with special needs in the classroom.
- Full Text:
- Date Issued: 2018
Stalking black swans, dragon kings, and market crashes on the JSE
- Authors: Zuka, Mawethu
- Date: 2015
- Subjects: Johannesburg Stock Exchange -- Research Stock exchanges -- South Africa , Stocks -- South Africa -- Johannesburg Financial crises -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10948/18376 , vital:28631
- Description: This paper examines bubbles on the JSE All Share Index as well as the critical time of the stock market crash from 2/01/ 2004 – 27/03/2014. The underlying hypothesis define bubbles as extreme and begin as a group of small events which grow in a super exponential form explained by a log periodic power law model (LPPL model). The hypothesis is based on the assumption of investors’ herding behavior, where investors collude by making investment decision correlated with their counterparties. The paper implements a Savitzky Golary Algorithm to detect peaks and calculate the critical time of the crash from the peaks. An Ordinary Least Squares (OLS) method is used to determine both the value of stock market price index at the critical time and the increase in the stock market price index over the time before the crash. The remaining parameters of the LPPL model are estimated using a Maximum Likelihood Estimation method. On the empirical results; 68 peaks were detected, and the LPPL model at the critical crash time is estimated 34736.586. Five bubbles are detected; the 15/8/2005 bubble, 28/5/2013 bubble, 23/8/2013 bubble, 5/11/2013, and 1/20/2014.
- Full Text:
- Date Issued: 2015
- Authors: Zuka, Mawethu
- Date: 2015
- Subjects: Johannesburg Stock Exchange -- Research Stock exchanges -- South Africa , Stocks -- South Africa -- Johannesburg Financial crises -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10948/18376 , vital:28631
- Description: This paper examines bubbles on the JSE All Share Index as well as the critical time of the stock market crash from 2/01/ 2004 – 27/03/2014. The underlying hypothesis define bubbles as extreme and begin as a group of small events which grow in a super exponential form explained by a log periodic power law model (LPPL model). The hypothesis is based on the assumption of investors’ herding behavior, where investors collude by making investment decision correlated with their counterparties. The paper implements a Savitzky Golary Algorithm to detect peaks and calculate the critical time of the crash from the peaks. An Ordinary Least Squares (OLS) method is used to determine both the value of stock market price index at the critical time and the increase in the stock market price index over the time before the crash. The remaining parameters of the LPPL model are estimated using a Maximum Likelihood Estimation method. On the empirical results; 68 peaks were detected, and the LPPL model at the critical crash time is estimated 34736.586. Five bubbles are detected; the 15/8/2005 bubble, 28/5/2013 bubble, 23/8/2013 bubble, 5/11/2013, and 1/20/2014.
- Full Text:
- Date Issued: 2015
Comparative phototransformation of environmental pollutants using metallophthalocyanines supported on electrospun polymer fibers
- Zugle, Ruphino, Nyokong, Tebello
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190509 , vital:45001 , xlink:href="https://doi.org/10.1002/app.38381"
- Description: The fluorescence and photoactivity of a series of Zn and Lu phthalocyanine complexes incorporated in various polymer fibers were investigated for the phototransformation of 4-chlorophenol, 4-nitrophenol, and methyl orange. The phthalocyanine complexes functionalized on polystyrene and polysulfone polymer fibers could be applied in the degradation of 4-chlorophenol, 4-nitrophenol, and methyl orange with 4-chlorophenol being much more susceptible to degradation while methyl orange was the least. Also polymer fibers of polystyrene were found to be reusable.
- Full Text:
- Date Issued: 2013
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190509 , vital:45001 , xlink:href="https://doi.org/10.1002/app.38381"
- Description: The fluorescence and photoactivity of a series of Zn and Lu phthalocyanine complexes incorporated in various polymer fibers were investigated for the phototransformation of 4-chlorophenol, 4-nitrophenol, and methyl orange. The phthalocyanine complexes functionalized on polystyrene and polysulfone polymer fibers could be applied in the degradation of 4-chlorophenol, 4-nitrophenol, and methyl orange with 4-chlorophenol being much more susceptible to degradation while methyl orange was the least. Also polymer fibers of polystyrene were found to be reusable.
- Full Text:
- Date Issued: 2013
Zinc (II) 2, 9, 16, 23-tetrakis [4-(N-methylpyridyloxy)]-phthalocyanine anchored on an electrospun polysulfone polymer fiber: Application for photosensitized conversion of methyl orange
- Zugle, Ruphino, Nyokong, Tebello
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232741 , vital:50020 , xlink:href="https://doi.org/10.1016/j.molcata.2012.10.001"
- Description: In this work, a comparative study of photodegradation of methyl orange, an azo dye, in homogeneous aqueous solution of a quarternized cationic zinc phthalocyanine and a heterogeneous catalytic system based on the same phthalocyanine anchored on polysulfone polymer fiber is presented. In both cases, conversion involved the azo bond of the dye with no detectable opening up of the aromatic benzene rings. The reaction kinetics in both cases were consistent with first order with the conversion occurring in the homogeneous system being faster than when the functionalized polymer fiber was used. The reaction products consisted of a coupling product as well as a series of oligopolymeric products.
- Full Text:
- Date Issued: 2013
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232741 , vital:50020 , xlink:href="https://doi.org/10.1016/j.molcata.2012.10.001"
- Description: In this work, a comparative study of photodegradation of methyl orange, an azo dye, in homogeneous aqueous solution of a quarternized cationic zinc phthalocyanine and a heterogeneous catalytic system based on the same phthalocyanine anchored on polysulfone polymer fiber is presented. In both cases, conversion involved the azo bond of the dye with no detectable opening up of the aromatic benzene rings. The reaction kinetics in both cases were consistent with first order with the conversion occurring in the homogeneous system being faster than when the functionalized polymer fiber was used. The reaction products consisted of a coupling product as well as a series of oligopolymeric products.
- Full Text:
- Date Issued: 2013
Electrospun polyacrylic acid polymer fibers functionalized with metallophthalocyanines for photosensitizing and gas sensing applications
- Zugle, Ruphino, Nyokong, Tebello
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243543 , vital:51162 , xlink:href="https://doi.org/10.1080/10601325.2012.662006"
- Description: The photophysical and photochemical properties of tetraaminophthalocyanine complexes of lutetium and zinc covalently linked to polyacrylic acid were studied alongside those of unsubstituted zinc phthalocyanine within the same polymeric fiber matrix. All three phthalocyanines within the solid fiber matrices showed photoactivity by the generation of singlet oxygen as was observed in solution. The fluorescence behaviors of the composite fibers equally parallel those in solution. For the unsubstituted zinc phthalocyanine composite, the fiber showed fluorescence quenching on interaction with gaseous nitrogen dioxide similar to that in DMF and, thus could be a promising nanofabric material in developing optoelectronic devices that are responsive to the gas.
- Full Text:
- Date Issued: 2012
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243543 , vital:51162 , xlink:href="https://doi.org/10.1080/10601325.2012.662006"
- Description: The photophysical and photochemical properties of tetraaminophthalocyanine complexes of lutetium and zinc covalently linked to polyacrylic acid were studied alongside those of unsubstituted zinc phthalocyanine within the same polymeric fiber matrix. All three phthalocyanines within the solid fiber matrices showed photoactivity by the generation of singlet oxygen as was observed in solution. The fluorescence behaviors of the composite fibers equally parallel those in solution. For the unsubstituted zinc phthalocyanine composite, the fiber showed fluorescence quenching on interaction with gaseous nitrogen dioxide similar to that in DMF and, thus could be a promising nanofabric material in developing optoelectronic devices that are responsive to the gas.
- Full Text:
- Date Issued: 2012
Photophysical characterization of dysprosium, erbium and lutetium phthalocyanines tetrasubstituted with phenoxy groups at non-peripheral positions
- Zugle, Ruphino, Litwinski, Christian, Nyokong, Tebello
- Authors: Zugle, Ruphino , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247561 , vital:51595 , xlink:href="https://doi.org/10.1016/j.poly.2011.03.030"
- Description: Dysprosium bis-phthalocyanine and monomeric phthalocyanines of erbium and lutetium with non-peripheral phenoxy substituents have been synthesized using two different preparative routes. Photophysical studies on these phthalocyanines revealed that the triplet states of dysprosium and erbium are not populated while the monomeric phthalocyanine complex of lutetium is populated with a quantum yield of 0.83 and a lifetime of 25 μs in DMSO. It was further found that the phthalocyanine complex of lutetium was capable of photochemical generation of singlet state molecular oxygen with yield of 0.71 in THF, thus a promising photosensitizer. However, the three phthalocyanine molecules have very low fluorescence quantum yields of less than 0.01.
- Full Text:
- Date Issued: 2011
- Authors: Zugle, Ruphino , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247561 , vital:51595 , xlink:href="https://doi.org/10.1016/j.poly.2011.03.030"
- Description: Dysprosium bis-phthalocyanine and monomeric phthalocyanines of erbium and lutetium with non-peripheral phenoxy substituents have been synthesized using two different preparative routes. Photophysical studies on these phthalocyanines revealed that the triplet states of dysprosium and erbium are not populated while the monomeric phthalocyanine complex of lutetium is populated with a quantum yield of 0.83 and a lifetime of 25 μs in DMSO. It was further found that the phthalocyanine complex of lutetium was capable of photochemical generation of singlet state molecular oxygen with yield of 0.71 in THF, thus a promising photosensitizer. However, the three phthalocyanine molecules have very low fluorescence quantum yields of less than 0.01.
- Full Text:
- Date Issued: 2011
Physico-chemical properties of lutetium phthalocyanine complexes in solution and in solid polystyrene polymer fibers and their application in photoconversion of 4-nitrophenol
- Zugle, Ruphino, Nyokong, Tebello
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243520 , vital:51160 , xlink:href="https://doi.org/10.1016/j.molcata.2012.02.010"
- Description: The photophysical and photochemical behavior of two phthalocyanine complexes of lutetium peripherally substituted with tetraphenoxy and tetra-2-pyridiloxy groups were studied in solution and when dispersed in polystyrene polymer fiber. The phthalocyanines were found not to fluoresce significantly in solution and not at all within the fiber matrix as compared with standard unsubstituted zinc phthalocyanine. They showed very promising photoactivity in solution with high singlet oxygen quantum yields. Their photoactivity within the polymer fiber matrix was also demonstrated with the photoconversion of 4-nitrophenol, a water pollutant. The photodegradation process with both phthalocyanines follows first order kinetics similar to that observed for the zinc phthalocyanine and the photo-products were found to be hydroquinone, benzoquinone and 4-nitrocatechol.
- Full Text:
- Date Issued: 2012
- Authors: Zugle, Ruphino , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243520 , vital:51160 , xlink:href="https://doi.org/10.1016/j.molcata.2012.02.010"
- Description: The photophysical and photochemical behavior of two phthalocyanine complexes of lutetium peripherally substituted with tetraphenoxy and tetra-2-pyridiloxy groups were studied in solution and when dispersed in polystyrene polymer fiber. The phthalocyanines were found not to fluoresce significantly in solution and not at all within the fiber matrix as compared with standard unsubstituted zinc phthalocyanine. They showed very promising photoactivity in solution with high singlet oxygen quantum yields. Their photoactivity within the polymer fiber matrix was also demonstrated with the photoconversion of 4-nitrophenol, a water pollutant. The photodegradation process with both phthalocyanines follows first order kinetics similar to that observed for the zinc phthalocyanine and the photo-products were found to be hydroquinone, benzoquinone and 4-nitrocatechol.
- Full Text:
- Date Issued: 2012
Phototransformation of pollutants using lutetium and zinc phthalocyanines anchored on electrospun polymer fibers
- Authors: Zugle, Ruphino
- Date: 2013
- Subjects: Electrospinning Phthalocyanines Lutetium Zinc Polymers Dysprosium Pollutants Air Pollution Photochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4286 , http://hdl.handle.net/10962/d1002962
- Description: Novel lanthanide phthalocyanines containing dysprosium, erbium and lutetium as central metals were synthesized using phthalonitrile:metal salt ratio of 4:1 or lower phthalonitrile content as well as using unmetallated phthalocyanine. They were characterized using various spectroscopic and elemental analyses. Dysprosium bis-phthalocyanine was obtained while monomers were obtained for erbium and lutetium phthalocyanines. Theopen-shelldysprosiumbis-phthalocyanine and the monomeric complex of the open-shell erbium were neither fluorescent nor showed the ability to generate singlet oxygen. The triplet states of all the lutetium phthalocyanines were found to be populated with high triplet quantum yields and corresponding high singlet oxygen quantum yields. The fluorescence quantum yields of the lutetium phthalocyanines were however found to be very low. The lutetium phthalocyanines together with unsubstituted zinc phthalocyanine and its derivatives were successfully incorporated into electrospun polymer fibers either by covalent linkage or sorption forces. Spectral characteristics of the functionalized electrospun polymer fibers indicated that the phthalocyanines were bound and their integrity maintained within the fiber matrices. Most importantly the fluorescence and photoactivity of the phthalocyanines were equally maintained within the electrospun fibers. The functionalized electrospun polymer fibers especially those containing the zinc phthalocyanines could qualitatively detect nitrogen dioxide, a known environmental air pollutant. Also all the functionalized electrospun polystyrene and polysulfone fibers containing lutetium and zinc phthalocyanines could be applied for the photoconversion of 4-chlorophenol, 4-nitrophenol and methyl orange. Those of polystyrene could be re-used. Polyacrylic acid and polyurethane functionalized electrospun fibers were found not to be suitable for photocatalytic applications in aqueous medium. 4-Chlorophenol was found to be more susceptible to photodegradation while methyl orange very difficult to degrade.
- Full Text:
- Date Issued: 2013
- Authors: Zugle, Ruphino
- Date: 2013
- Subjects: Electrospinning Phthalocyanines Lutetium Zinc Polymers Dysprosium Pollutants Air Pollution Photochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4286 , http://hdl.handle.net/10962/d1002962
- Description: Novel lanthanide phthalocyanines containing dysprosium, erbium and lutetium as central metals were synthesized using phthalonitrile:metal salt ratio of 4:1 or lower phthalonitrile content as well as using unmetallated phthalocyanine. They were characterized using various spectroscopic and elemental analyses. Dysprosium bis-phthalocyanine was obtained while monomers were obtained for erbium and lutetium phthalocyanines. Theopen-shelldysprosiumbis-phthalocyanine and the monomeric complex of the open-shell erbium were neither fluorescent nor showed the ability to generate singlet oxygen. The triplet states of all the lutetium phthalocyanines were found to be populated with high triplet quantum yields and corresponding high singlet oxygen quantum yields. The fluorescence quantum yields of the lutetium phthalocyanines were however found to be very low. The lutetium phthalocyanines together with unsubstituted zinc phthalocyanine and its derivatives were successfully incorporated into electrospun polymer fibers either by covalent linkage or sorption forces. Spectral characteristics of the functionalized electrospun polymer fibers indicated that the phthalocyanines were bound and their integrity maintained within the fiber matrices. Most importantly the fluorescence and photoactivity of the phthalocyanines were equally maintained within the electrospun fibers. The functionalized electrospun polymer fibers especially those containing the zinc phthalocyanines could qualitatively detect nitrogen dioxide, a known environmental air pollutant. Also all the functionalized electrospun polystyrene and polysulfone fibers containing lutetium and zinc phthalocyanines could be applied for the photoconversion of 4-chlorophenol, 4-nitrophenol and methyl orange. Those of polystyrene could be re-used. Polyacrylic acid and polyurethane functionalized electrospun fibers were found not to be suitable for photocatalytic applications in aqueous medium. 4-Chlorophenol was found to be more susceptible to photodegradation while methyl orange very difficult to degrade.
- Full Text:
- Date Issued: 2013
Photooxidation of 4-chlorophenol sensitized by lutetium tetraphenoxy phthalocyanine anchored on electrospun polystyrene polymer fiber
- Zugle, Ruphino, Antunes, Edith M, Khene, Samson M, Nyokong, Tebello
- Authors: Zugle, Ruphino , Antunes, Edith M , Khene, Samson M , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245787 , vital:51405 , xlink:href="https://doi.org/10.1016/j.poly.2011.11.005"
- Description: An electrospun polystyrene (PS) fiber incorporating tetraphenoxy phthalocyanine complex of lutetium (LuTPPc/PS) as a photosensitizer was applied for the degradation of 4-chlorophenol in aqueous solution in the presence of visible light. The photocatalytic activity of the LuTPPc in the fiber was compared to that of zinc phthalocyanine (ZnPc) incorporated into the PS fiber, and the former showed higher activity. UV–Vis spectral changes of sample solutions indicated transformation of the analyte with first order kinetics and half-lives that are within one and half hours for LuTPPc/PS. Products identified from the spectral changes and gas chromatography were benzoquinone, hydroquinone and 4,4′-dihydroxydiphenol suggesting that the photodegradation of 4-chlorophenol was through both Types I and II mechanisms.
- Full Text:
- Date Issued: 2012
- Authors: Zugle, Ruphino , Antunes, Edith M , Khene, Samson M , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245787 , vital:51405 , xlink:href="https://doi.org/10.1016/j.poly.2011.11.005"
- Description: An electrospun polystyrene (PS) fiber incorporating tetraphenoxy phthalocyanine complex of lutetium (LuTPPc/PS) as a photosensitizer was applied for the degradation of 4-chlorophenol in aqueous solution in the presence of visible light. The photocatalytic activity of the LuTPPc in the fiber was compared to that of zinc phthalocyanine (ZnPc) incorporated into the PS fiber, and the former showed higher activity. UV–Vis spectral changes of sample solutions indicated transformation of the analyte with first order kinetics and half-lives that are within one and half hours for LuTPPc/PS. Products identified from the spectral changes and gas chromatography were benzoquinone, hydroquinone and 4,4′-dihydroxydiphenol suggesting that the photodegradation of 4-chlorophenol was through both Types I and II mechanisms.
- Full Text:
- Date Issued: 2012
Photophysical and photochemical behavior of electrospun fibers of a polyurethane polymer chemically linked to lutetium carboxyphenoxy phthalocyanine
- Zugle, Ruphino, Litwinski, Christian, Torto, Nelson, Nyokong, Tebello
- Authors: Zugle, Ruphino , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248428 , vital:51685 , xlink:href="https://doi.org/10.1039/C1NJ20126C"
- Description: A phthalocyanine complex of lutetium substituted with four peripherally substituted 4-carboxyphenoxy groups was synthesized using cyclotetramerisation reaction. Its structure was elucidated using conventional spectroscopic methods and elemental analysis. The spectral behavior of the complex was studied in DMF solution and in a solid polyurethane fiber matrix. The UV-Visible spectrum showed a red shift in its Q-band maximum absorption within the fiber as compared to that in solution. The triplet quantum yield in DMF was determined to be 0.51 with a lifetime of 2.7 μs and a singlet oxygen quantum yield of 0.33 with a lifetime of 19.85 μs in the same solvent. The functionalized phthalocyanine fiber could be a promising fabric material for applications such as self-disinfecting in wound dressing. A method based on the conversion of ADMA was used to estimate the singlet oxygen quantum yield of the Pc in the hybrid fiber. An estimated singlet oxygen quantum yield value of 0.11 in aqueous medium was obtained. The fluorescence quantum yield of the Pc was found to be 0.01 with a lifetime of 3.20 ns in DMF.
- Full Text:
- Date Issued: 2011
- Authors: Zugle, Ruphino , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248428 , vital:51685 , xlink:href="https://doi.org/10.1039/C1NJ20126C"
- Description: A phthalocyanine complex of lutetium substituted with four peripherally substituted 4-carboxyphenoxy groups was synthesized using cyclotetramerisation reaction. Its structure was elucidated using conventional spectroscopic methods and elemental analysis. The spectral behavior of the complex was studied in DMF solution and in a solid polyurethane fiber matrix. The UV-Visible spectrum showed a red shift in its Q-band maximum absorption within the fiber as compared to that in solution. The triplet quantum yield in DMF was determined to be 0.51 with a lifetime of 2.7 μs and a singlet oxygen quantum yield of 0.33 with a lifetime of 19.85 μs in the same solvent. The functionalized phthalocyanine fiber could be a promising fabric material for applications such as self-disinfecting in wound dressing. A method based on the conversion of ADMA was used to estimate the singlet oxygen quantum yield of the Pc in the hybrid fiber. An estimated singlet oxygen quantum yield value of 0.11 in aqueous medium was obtained. The fluorescence quantum yield of the Pc was found to be 0.01 with a lifetime of 3.20 ns in DMF.
- Full Text:
- Date Issued: 2011
Pavoclinus caeruleopunctatus, a new species of clinid fish (Perciformes: Clinidae) from South Africa
- Zsilavecz, Guido, J.L.B. Smith Institute of Ichthyology
- Authors: Zsilavecz, Guido , J.L.B. Smith Institute of Ichthyology
- Date: 2001-08
- Subjects: Clinidae -- South Atlantic Ocean -- Classification , Clinidae -- South Africa -- Classification
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/71066 , vital:29774 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 66 , A new species of clinid fish, Pavoclinns caeruleopunctatus, is described from specimens collected and observed in 6 - 25 m, around the Cape Peninsula, on the southwest coast of South Africa. Pavoclinus caeruleopunctatus is distinguished from similar species by the first 3 dorsal-fin spines forming a moderate crest, a notch between the 3rd and 4th dorsal-fin spines, 1 - 3 soft dorsal rays, an anteriorly rounded head profile, and colour pattern; most characteristic in live specimens are the vivid blue spots in front and behind the eye, and also usually on the flanks.
- Full Text:
- Date Issued: 2001-08
Pavoclinus caeruleopunctatus, a new species of clinid fish (Perciformes: Clinidae) from South Africa
- Authors: Zsilavecz, Guido , J.L.B. Smith Institute of Ichthyology
- Date: 2001-08
- Subjects: Clinidae -- South Atlantic Ocean -- Classification , Clinidae -- South Africa -- Classification
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/71066 , vital:29774 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 66 , A new species of clinid fish, Pavoclinns caeruleopunctatus, is described from specimens collected and observed in 6 - 25 m, around the Cape Peninsula, on the southwest coast of South Africa. Pavoclinus caeruleopunctatus is distinguished from similar species by the first 3 dorsal-fin spines forming a moderate crest, a notch between the 3rd and 4th dorsal-fin spines, 1 - 3 soft dorsal rays, an anteriorly rounded head profile, and colour pattern; most characteristic in live specimens are the vivid blue spots in front and behind the eye, and also usually on the flanks.
- Full Text:
- Date Issued: 2001-08
The use of the cochineal insect, Dactylopius tomentosus Lamarck, as a biological control agent for the invasive alien thistle cholla, Cylindropuntia pallida (Rose) F.M. Knuth in South Africa
- Authors: Zozo, Ekhona
- Date: 2022-04-06
- Subjects: Cochineal insect , Thistles Biological control South Africa , Alien plants South Africa , Invasive plants South Africa , Cactus South Africa , Biological assay
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/233823 , vital:50131
- Description: Cylindropuntia pallida (Rose) F.M. Knuth (Cactaceae) is an invasive alien plant in South Africa indigenous in the southern U.S.A. and Mexico. Large infestations of this species can be found in the Kalahari and arid Karoo regions of South Africa, which is also present in Namibia. Because it is a very spiny cactus, dense infestations have a negative impact on agriculture and natural ecosystems. This cactus has become naturalised to the extent that eradication is impossible and the negative impacts are steadily increasing due to its increasing distribution and density. The cochineal insect, Dactylopius tomentosus Lamarck (Dactylopiidae), is native in Mexico and parts of North America, such as Texas, Arizona, and New Mexico in the U.S.A. This cochineal species is highly specialized and associated only with Cylindropuntia species, a group of cacti that are primarily restricted to the same areas. It has been introduced into Australia and South Africa as a biological control agent to control various invasive alien Cylindropuntia species. This cochineal species has several biotypes specific to certain Cylindropuntia species hosts. A biotype is a clade that cannot be differentiated morphologically from others but has different host ranges and impacts depending on the host plant species. Included amongst biotypes that have been released in South Africa are D. tomentosus ‘imbricata’ and D. tomentosus ‘cholla’ for the biological control of Cylindropuntia imbricata (Haw.) F.M. Knuth (Cactaceae) and Cylindropuntia fulgida (Engelmann) F.M. Knuth var. mamillata (Schott ex Engelmann) Backeb. (Cactaceae), respectively. These biotypes have resulted in both host plants being under substantial control in South Africa. The first part of this thesis evaluated which of the two D. tomentosus biotypes already in use in South Africa could be an effective biological control agent for C. pallida. This was done by assessing the fitness of the cochineals on the three cactus species and assessing the impact that each of the cochineals has on each of the target weed species. Should these biotypes prove ineffective, there is a third biotype, namely D. tomentosus ‘californica var. parkerii’, which researchers in Australia have worked on and have found to be suitably host-specific for release in Australia and suitably damaging to C. pallida in that country. Therefore, this new biotype could be released in South Africa if it is required. Sexually compatible biological control agents, especially those closely related and occurring in close spatial proximity to one another, may interbreed and the impacts of this hybridisation are difficult to predict. It is important to understand the outcomes of the hybridisation of cochineal because it can affect the impact of the biological control agents and thus the control of the target weed. The second part of this thesis investigated the impacts of the hybridisation of the two cochineal biotypes by assessing the damage the agents would have on the target weed, and on C. imbricata and C. fulgida var. mamillata, in the presence of one or both cochineal biotypes. The ‘cholla’ biotype performed better on C. pallida than the ‘imbricata’ biotype, but neither biotype could control C. pallida to an extent similar to the control they provide for their respective target weeds, C. imbricata and C. fulgida var. mamillata. Both the ‘cholla’ biotype and hybrids of the two biotypes of cochineal were effective at killing C. pallida when both C. imbricata and C. fulgida var. mamillata were also present. This suggests that the ‘cholla’ or hybrids may be effective at controlling C. pallida when either C. imbricata or C. fulgida var. mamillata are also present in the field due to the high population density of cochineal that results under these circumstances. There are, however, many C. pallida infestations in South Africa where the plant is problematic and is isolated from other Cylindropuntia species, and these populations are unlikely to be controlled by the ‘cholla’ biotype or the hybrids. Neither of the cochineal biotypes that are used for biological control in South Africa are suitably damaging to C. pallida to warrant their use as biological control agents for this species. Dactylopius tomentosus ‘californica var. parkerii’ is therefore recommended for release based on its host-specificity and impact to C. pallida in Australia. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Zozo, Ekhona
- Date: 2022-04-06
- Subjects: Cochineal insect , Thistles Biological control South Africa , Alien plants South Africa , Invasive plants South Africa , Cactus South Africa , Biological assay
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/233823 , vital:50131
- Description: Cylindropuntia pallida (Rose) F.M. Knuth (Cactaceae) is an invasive alien plant in South Africa indigenous in the southern U.S.A. and Mexico. Large infestations of this species can be found in the Kalahari and arid Karoo regions of South Africa, which is also present in Namibia. Because it is a very spiny cactus, dense infestations have a negative impact on agriculture and natural ecosystems. This cactus has become naturalised to the extent that eradication is impossible and the negative impacts are steadily increasing due to its increasing distribution and density. The cochineal insect, Dactylopius tomentosus Lamarck (Dactylopiidae), is native in Mexico and parts of North America, such as Texas, Arizona, and New Mexico in the U.S.A. This cochineal species is highly specialized and associated only with Cylindropuntia species, a group of cacti that are primarily restricted to the same areas. It has been introduced into Australia and South Africa as a biological control agent to control various invasive alien Cylindropuntia species. This cochineal species has several biotypes specific to certain Cylindropuntia species hosts. A biotype is a clade that cannot be differentiated morphologically from others but has different host ranges and impacts depending on the host plant species. Included amongst biotypes that have been released in South Africa are D. tomentosus ‘imbricata’ and D. tomentosus ‘cholla’ for the biological control of Cylindropuntia imbricata (Haw.) F.M. Knuth (Cactaceae) and Cylindropuntia fulgida (Engelmann) F.M. Knuth var. mamillata (Schott ex Engelmann) Backeb. (Cactaceae), respectively. These biotypes have resulted in both host plants being under substantial control in South Africa. The first part of this thesis evaluated which of the two D. tomentosus biotypes already in use in South Africa could be an effective biological control agent for C. pallida. This was done by assessing the fitness of the cochineals on the three cactus species and assessing the impact that each of the cochineals has on each of the target weed species. Should these biotypes prove ineffective, there is a third biotype, namely D. tomentosus ‘californica var. parkerii’, which researchers in Australia have worked on and have found to be suitably host-specific for release in Australia and suitably damaging to C. pallida in that country. Therefore, this new biotype could be released in South Africa if it is required. Sexually compatible biological control agents, especially those closely related and occurring in close spatial proximity to one another, may interbreed and the impacts of this hybridisation are difficult to predict. It is important to understand the outcomes of the hybridisation of cochineal because it can affect the impact of the biological control agents and thus the control of the target weed. The second part of this thesis investigated the impacts of the hybridisation of the two cochineal biotypes by assessing the damage the agents would have on the target weed, and on C. imbricata and C. fulgida var. mamillata, in the presence of one or both cochineal biotypes. The ‘cholla’ biotype performed better on C. pallida than the ‘imbricata’ biotype, but neither biotype could control C. pallida to an extent similar to the control they provide for their respective target weeds, C. imbricata and C. fulgida var. mamillata. Both the ‘cholla’ biotype and hybrids of the two biotypes of cochineal were effective at killing C. pallida when both C. imbricata and C. fulgida var. mamillata were also present. This suggests that the ‘cholla’ or hybrids may be effective at controlling C. pallida when either C. imbricata or C. fulgida var. mamillata are also present in the field due to the high population density of cochineal that results under these circumstances. There are, however, many C. pallida infestations in South Africa where the plant is problematic and is isolated from other Cylindropuntia species, and these populations are unlikely to be controlled by the ‘cholla’ biotype or the hybrids. Neither of the cochineal biotypes that are used for biological control in South Africa are suitably damaging to C. pallida to warrant their use as biological control agents for this species. Dactylopius tomentosus ‘californica var. parkerii’ is therefore recommended for release based on its host-specificity and impact to C. pallida in Australia. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
- Full Text:
- Date Issued: 2022-04-06
A case study of how a leader shaped the culture of an organisation during a post-merger integration
- Authors: Zozi, Vuyokazi
- Date: 2020
- Subjects: Corporate culture -- South Africa -- East London , Leadership -- South Africa -- East London , Organizational behavior -- South Africa -- East London , Strategic planning -- South Africa -- East London , Mission statements -- South Africa -- East London , Government accountability -- South Africa -- East London , Government corporations -- South Africa -- East London , Consolidation and merger of corporations -- South Africa -- East London , Consolidation and merger of corporations -- Management , Crisis management -- South Africa -- East London , Core competencies -- South Africa -- East London , Resource allocation -- South Africa -- East London , Personnel management -- South Africa -- East London , Communication in management -- South Africa -- East London , Qualitative research
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/146643 , vital:38544
- Description: This research took the form of a case study of the post-merger integration of a government organisation. The study had four objectives, namely to: (1) describe the cultural value of accountability; (2) analyse how strategic leadership and relational leadership roles were exercised to address post-merger integration challenges; (3) analyse how a leader applied selected primary mechanisms to shape organisational culture; (4) analyse how strategic and relational leadership complemented each other in addressing the challenges of post-merger integration and thereby shaping a culture of accountability; and (5) describe how some of the secondary articulation and reinforcing mechanisms supported the culture that was created through primary mechanisms. The literature reviewed, identified some of the critical challenges that are experienced in a post-merger integration, and highlighted the role of leadership in culture formation. The critical challenges that were identified are as follows: What is the vision and organisational purpose? How does the leader structure the organisation? What kind of culture does the leader need to create? How does the leader maintain trust and keep communication with employees? How does a leader build new core competences and develop human capital? Two leadership approaches were adopted, namely strategic and relational leadership. These two leadership approaches were selected because, based on a review of the literature, they appeared to address these post-integration challenges. The roles associated with strategic leadership that were investigated, were creating a vision and purpose for the organisation, developing core competences and developing human capital. From the perspective of relational leadership, this study was concerned with how a leader communicated through regular formal and informal dialogues to keep employees abreast of things, and how the leader built trust. In reviewing the literature linking leadership and culture, the work of Schein (2010) featured prominently. Schein (2010) referred to primary embedding mechanisms that create culture and secondary articulation and reinforcing mechanisms that reinforce or support the culture being created through the primary mechanisms. This study looked at how that happens, and hence six propositions were crafted from the literature. These propositions are as follows: (1) Formal dialogues between the leader and employees demonstrate what the leader pays attention to, measures and controls, which then clarifies what the employees are accountable for. (2) What the leader pays attention to, measures and controls during regular informal interactions between the leader and employees, contributes to strong mutual relationships between them, which promotes ownership and accountability amongst employees for their actions. (3) A leader who behaves consistently when handling critical incidents and organisational crises, is trusted by employees, who then act responsibly and take full responsibility for their actions, and even their mistakes. (4) A leader creates a vision and sense of purpose for the organisation through what he pays attention to, measures and controls, thereby clarifying for employees what they are required to do. (5) A leader who pays attention to developing the organisational core competence and allocates resources to it, instils confidence in his employees with regards to carrying out their own responsibilities. (6) A leader who develops human capital through the allocation of additional resources, thereby instilling confidence in employees who are willing and able to realise or take up their responsibilities. This research adopted a qualitative approach. Data was collected through conducting interviews and the analysis of relevant documents. A deductive thematic analysis of the data was used for the purpose of identifying, analysing and reporting patterns, or themes within the data collected. The research confirmed these propositions as being relevant to the case study. It also confirmed that strategic and relational leadership as reflected in the propositions have complemented one another in the successful implementation of the post-merger integration, thereby shaping a particular culture. It was concluded that the challenges associated with a post-merger integration could not have been addressed through only one of the leadership approaches. The findings of the study also recognised that an architectural role was also required. That is, in a merger, the structure has to be carefully designed and not taken for granted. It was therefore recognised as a critical leadership role. The study considers the implications of the findings and makes recommendations for managers of this organisation, as well as for other organisations that are engaging in a post-merger integration. It further outlines the limitations, delimitations as well as the contribution that the study has made to the body of knowledge. Some of the recommendations made for further research were to analyse how other primary mechanisms that were not part of the propositions may shape the organisational culture; and to research how architectural leadership roles combine with strategic and relational leadership to address post-merger integration challenges. Lastly, this study has explained how leadership, through various mechanisms, shaped a culture of accountability. Other studies can be done using a similar design with different theories of leadership and other mechanisms that apply to shaping other kinds of cultural values.
- Full Text:
- Date Issued: 2020
- Authors: Zozi, Vuyokazi
- Date: 2020
- Subjects: Corporate culture -- South Africa -- East London , Leadership -- South Africa -- East London , Organizational behavior -- South Africa -- East London , Strategic planning -- South Africa -- East London , Mission statements -- South Africa -- East London , Government accountability -- South Africa -- East London , Government corporations -- South Africa -- East London , Consolidation and merger of corporations -- South Africa -- East London , Consolidation and merger of corporations -- Management , Crisis management -- South Africa -- East London , Core competencies -- South Africa -- East London , Resource allocation -- South Africa -- East London , Personnel management -- South Africa -- East London , Communication in management -- South Africa -- East London , Qualitative research
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/146643 , vital:38544
- Description: This research took the form of a case study of the post-merger integration of a government organisation. The study had four objectives, namely to: (1) describe the cultural value of accountability; (2) analyse how strategic leadership and relational leadership roles were exercised to address post-merger integration challenges; (3) analyse how a leader applied selected primary mechanisms to shape organisational culture; (4) analyse how strategic and relational leadership complemented each other in addressing the challenges of post-merger integration and thereby shaping a culture of accountability; and (5) describe how some of the secondary articulation and reinforcing mechanisms supported the culture that was created through primary mechanisms. The literature reviewed, identified some of the critical challenges that are experienced in a post-merger integration, and highlighted the role of leadership in culture formation. The critical challenges that were identified are as follows: What is the vision and organisational purpose? How does the leader structure the organisation? What kind of culture does the leader need to create? How does the leader maintain trust and keep communication with employees? How does a leader build new core competences and develop human capital? Two leadership approaches were adopted, namely strategic and relational leadership. These two leadership approaches were selected because, based on a review of the literature, they appeared to address these post-integration challenges. The roles associated with strategic leadership that were investigated, were creating a vision and purpose for the organisation, developing core competences and developing human capital. From the perspective of relational leadership, this study was concerned with how a leader communicated through regular formal and informal dialogues to keep employees abreast of things, and how the leader built trust. In reviewing the literature linking leadership and culture, the work of Schein (2010) featured prominently. Schein (2010) referred to primary embedding mechanisms that create culture and secondary articulation and reinforcing mechanisms that reinforce or support the culture being created through the primary mechanisms. This study looked at how that happens, and hence six propositions were crafted from the literature. These propositions are as follows: (1) Formal dialogues between the leader and employees demonstrate what the leader pays attention to, measures and controls, which then clarifies what the employees are accountable for. (2) What the leader pays attention to, measures and controls during regular informal interactions between the leader and employees, contributes to strong mutual relationships between them, which promotes ownership and accountability amongst employees for their actions. (3) A leader who behaves consistently when handling critical incidents and organisational crises, is trusted by employees, who then act responsibly and take full responsibility for their actions, and even their mistakes. (4) A leader creates a vision and sense of purpose for the organisation through what he pays attention to, measures and controls, thereby clarifying for employees what they are required to do. (5) A leader who pays attention to developing the organisational core competence and allocates resources to it, instils confidence in his employees with regards to carrying out their own responsibilities. (6) A leader who develops human capital through the allocation of additional resources, thereby instilling confidence in employees who are willing and able to realise or take up their responsibilities. This research adopted a qualitative approach. Data was collected through conducting interviews and the analysis of relevant documents. A deductive thematic analysis of the data was used for the purpose of identifying, analysing and reporting patterns, or themes within the data collected. The research confirmed these propositions as being relevant to the case study. It also confirmed that strategic and relational leadership as reflected in the propositions have complemented one another in the successful implementation of the post-merger integration, thereby shaping a particular culture. It was concluded that the challenges associated with a post-merger integration could not have been addressed through only one of the leadership approaches. The findings of the study also recognised that an architectural role was also required. That is, in a merger, the structure has to be carefully designed and not taken for granted. It was therefore recognised as a critical leadership role. The study considers the implications of the findings and makes recommendations for managers of this organisation, as well as for other organisations that are engaging in a post-merger integration. It further outlines the limitations, delimitations as well as the contribution that the study has made to the body of knowledge. Some of the recommendations made for further research were to analyse how other primary mechanisms that were not part of the propositions may shape the organisational culture; and to research how architectural leadership roles combine with strategic and relational leadership to address post-merger integration challenges. Lastly, this study has explained how leadership, through various mechanisms, shaped a culture of accountability. Other studies can be done using a similar design with different theories of leadership and other mechanisms that apply to shaping other kinds of cultural values.
- Full Text:
- Date Issued: 2020
In-vitroevaluation of bridelia ferruginea extract gold nanoparticles for the treatment of colon cancer
- Zosela, Itumeleng, Davids, Hajierah
- Authors: Zosela, Itumeleng , Davids, Hajierah
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54124 , vital:46311
- Description: Colorectal cancer (CRC) has become a health burden, being the third common cancer worldwide. Treatment of colorectal cancer is very important to manage the high prevalence rate of this disease. The available treatments for CRC have their drawbacks and side effects. Available treatments of colon cancer include surgery, chemotherapy, and radiation. Due to the side effects associated with these treatments, alternative treatments that pose less side effects are being developed worldwide. Nanotechnologies have gained global consideration due to their potential to improve the current standards and techniques for the diagnosis and treatment. The use of plants for synthesis of gold nanoparticles has opened a new venture of synthesizing environmentally friendly and cost-effective nanoparticles which possess great properties for CRC treatment. The aim of this study was to investigate the use of green synthesized AuNPs from Bridelia ferruginea for potential cancer treatment. In this work study gold nanoparticles were synthesized utilizing Bridelia ferruginea stem bark extract. The nanoparticles were characterized using UV–Vis spectroscopy, Dynamic Light Scattering (DLS), Fourier Transform Infrared Spectroscopy (FTIR) and High-Resolution Transmission Electron Microscopy (HRTEM). The in vitroanti cancer activity of the AuNPs was investigated using Presto Blue assay, cellular morphology, caspase 3/7 assay on the human colon cancer cell line at different times to assess the optimum time for cell death. The cellular uptake and localization of AuNPs was investigated using HRTEM to assess uptake and location of the AuNPs within the cell. Results obtained from this study showed that the AuNP synthesis from Bridellia ferrugenia was successful. The Presto Blue cell viability results showed that the AuNPs reduced cell viability (%) significantly (p<0.05) after 24 h. The optimum treatment time of HT-29 cells with AuNPs was determined to be 24 h. The apoptotic effects of the AuNPs were assessed using Cell Event reagent, and the results from this assay indicated that caspase 3/7 was activated with treatment with AuNPs which induced cell death via apoptosis. The HRTEM results indicated that there was no uptake of AuNP targeting in HT-29 therefore localization could not be determined. It can be concluded that the AuNPs synthesized from Bridellia ferrugenia have anti-cancer properties and are able to induce cell death through apoptosis. Furthermore, this study revealed that optimization of the AuNPs for cellular uptake is needed to further understand the interaction between the nanoparticles and the cells. This will provide more insight on how cellular death is induced by the nanoparticles. , Thesis (MSc) -- Faculty of Science, Department of Biochemistry and Microbiology (including Physiology), 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Zosela, Itumeleng , Davids, Hajierah
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54124 , vital:46311
- Description: Colorectal cancer (CRC) has become a health burden, being the third common cancer worldwide. Treatment of colorectal cancer is very important to manage the high prevalence rate of this disease. The available treatments for CRC have their drawbacks and side effects. Available treatments of colon cancer include surgery, chemotherapy, and radiation. Due to the side effects associated with these treatments, alternative treatments that pose less side effects are being developed worldwide. Nanotechnologies have gained global consideration due to their potential to improve the current standards and techniques for the diagnosis and treatment. The use of plants for synthesis of gold nanoparticles has opened a new venture of synthesizing environmentally friendly and cost-effective nanoparticles which possess great properties for CRC treatment. The aim of this study was to investigate the use of green synthesized AuNPs from Bridelia ferruginea for potential cancer treatment. In this work study gold nanoparticles were synthesized utilizing Bridelia ferruginea stem bark extract. The nanoparticles were characterized using UV–Vis spectroscopy, Dynamic Light Scattering (DLS), Fourier Transform Infrared Spectroscopy (FTIR) and High-Resolution Transmission Electron Microscopy (HRTEM). The in vitroanti cancer activity of the AuNPs was investigated using Presto Blue assay, cellular morphology, caspase 3/7 assay on the human colon cancer cell line at different times to assess the optimum time for cell death. The cellular uptake and localization of AuNPs was investigated using HRTEM to assess uptake and location of the AuNPs within the cell. Results obtained from this study showed that the AuNP synthesis from Bridellia ferrugenia was successful. The Presto Blue cell viability results showed that the AuNPs reduced cell viability (%) significantly (p<0.05) after 24 h. The optimum treatment time of HT-29 cells with AuNPs was determined to be 24 h. The apoptotic effects of the AuNPs were assessed using Cell Event reagent, and the results from this assay indicated that caspase 3/7 was activated with treatment with AuNPs which induced cell death via apoptosis. The HRTEM results indicated that there was no uptake of AuNP targeting in HT-29 therefore localization could not be determined. It can be concluded that the AuNPs synthesized from Bridellia ferrugenia have anti-cancer properties and are able to induce cell death through apoptosis. Furthermore, this study revealed that optimization of the AuNPs for cellular uptake is needed to further understand the interaction between the nanoparticles and the cells. This will provide more insight on how cellular death is induced by the nanoparticles. , Thesis (MSc) -- Faculty of Science, Department of Biochemistry and Microbiology (including Physiology), 2021
- Full Text:
- Date Issued: 2021-12