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
Spectroscopic and physicochemical behavior of magnesium phthalocyanine derivatives mono-substituted with a carboxylic acid group
- Nombona, Nolwazi, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244450 , vital:51258 , xlink:href="https://doi.org/10.1016/j.molstruc.2011.12.051"
- Description: This work reports on the synthesis of novel unsymmetrically substituted magnesium phthalocyanine complexes containing one carboxyl group. The physicochemical behavior of these complexes were compared with those of their unmetallated and zinc counterparts. The MgPcs showed interesting absorption spectra with [8,15,22-Tris-(naphtho)-4,5-(3-carboxy-1,2-dioxyphenyl)phthalocyaninato]magnesium (II) showing a large split in the Q band whereas [8,15,22-Tris-(naphtho)-2-(carboxy) phthalocyaninato]magnesium(II) presented only a small splitting. The magnesium phthalocyanine derivatives displayed higher fluorescence quantum yields compared to unmetallated and zinc phthalocyanine counterparts. The latter gave admirable triplet and singlet oxygen quantum yields. These molecules can distinctly be employed in the field of photodynamic therapy in combination with fluorescence imaging.
- Full Text:
- Date Issued: 2012
- Authors: Nombona, Nolwazi , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/244450 , vital:51258 , xlink:href="https://doi.org/10.1016/j.molstruc.2011.12.051"
- Description: This work reports on the synthesis of novel unsymmetrically substituted magnesium phthalocyanine complexes containing one carboxyl group. The physicochemical behavior of these complexes were compared with those of their unmetallated and zinc counterparts. The MgPcs showed interesting absorption spectra with [8,15,22-Tris-(naphtho)-4,5-(3-carboxy-1,2-dioxyphenyl)phthalocyaninato]magnesium (II) showing a large split in the Q band whereas [8,15,22-Tris-(naphtho)-2-(carboxy) phthalocyaninato]magnesium(II) presented only a small splitting. The magnesium phthalocyanine derivatives displayed higher fluorescence quantum yields compared to unmetallated and zinc phthalocyanine counterparts. The latter gave admirable triplet and singlet oxygen quantum yields. These molecules can distinctly be employed in the field of photodynamic therapy in combination with fluorescence imaging.
- Full Text:
- Date Issued: 2012
Spectroscopic behavior of cationic metallophthalocyanines in the presence of anionic quantum dots
- Idowu, Mopelola, Nyokong, Tebello
- Authors: Idowu, Mopelola , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262699 , vital:53545 , xlink:href="https://doi.org/10.1016/j.saa.2009.10.050"
- Description: The interactions and spectroscopic properties between cationic zinc phthalocyanine derivatives (peripherally and non-peripherally tetrasubstituted and peripherally octa substituted with 2-diethylmethylaminoethylsulfanyl (βTZnPc, αTZnPc and βOZnPc)) and CdTe core quantum dots (QDs) capped with mercaptopropionic acid or thioglycolic acid (represented as CdTe@MPA and CdTe@TGA, respectively) have been studied in methanol:water mixture. Strong coupling of MPcs was deduced from the interaction since the UV–vis spectroscopic studies of the ground state complex formed on mixing both components showed loss of the phthalocyanine monomeric band with the formation of a dimeric band (spectrum of aggregated species). The dimerization constants were of the order of 104 M−1.
- Full Text:
- Date Issued: 2010
- Authors: Idowu, Mopelola , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262699 , vital:53545 , xlink:href="https://doi.org/10.1016/j.saa.2009.10.050"
- Description: The interactions and spectroscopic properties between cationic zinc phthalocyanine derivatives (peripherally and non-peripherally tetrasubstituted and peripherally octa substituted with 2-diethylmethylaminoethylsulfanyl (βTZnPc, αTZnPc and βOZnPc)) and CdTe core quantum dots (QDs) capped with mercaptopropionic acid or thioglycolic acid (represented as CdTe@MPA and CdTe@TGA, respectively) have been studied in methanol:water mixture. Strong coupling of MPcs was deduced from the interaction since the UV–vis spectroscopic studies of the ground state complex formed on mixing both components showed loss of the phthalocyanine monomeric band with the formation of a dimeric band (spectrum of aggregated species). The dimerization constants were of the order of 104 M−1.
- Full Text:
- Date Issued: 2010
Spectroscopic characterisation and interactions of sulfonated titanium and tantalum phthalocyanines with methyl viologen
- Tau, Prudence, Nyokong, Tebello
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283129 , vital:55913 , xlink:href="https://doi.org/10.1016/j.ica.2006.12.035"
- Description: Sulfonated OTiPc(S)n and (Cl3)TaPc(S)n complexes are prepared and characterised by spectroscopic methods in DMSO, methanol and PBS 7.4. The dominant sulfonated species was the disulfophthalocyanine. OTiPc(S)n is highly aggregated in PBS 7.4 solution and tends to partially monomerise, on addition of Triton X-100, while (Cl3)TaPc(S)n showed broadened spectra in all solvents and was not affected by Triton X-100. The absorption and excitation spectra of OTiPc(S)n are similar and are mirror images of their emission spectra in DMSO, but differ in PBS and methanol. The fluorescence quantum yields (ϕF) and lifetimes (τF) were larger in DMSO than in methanol. In PBS 7.4, however, the ϕF and τF values were significantly smaller for OTiPc(S)n, which is typical of aggregated species. Gradual addition of the electron-acceptor MV2+ to solutions of MPc(S)n complexes resulted in the fluorescence quenching of complexes with higher quenching observed for OTiPc(S)n. The interaction of the MPc(S)n complexes with MV2+, and hence the stoichiometry and association constants are evaluated by means of Job method.
- Full Text:
- Date Issued: 2007
- Authors: Tau, Prudence , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283129 , vital:55913 , xlink:href="https://doi.org/10.1016/j.ica.2006.12.035"
- Description: Sulfonated OTiPc(S)n and (Cl3)TaPc(S)n complexes are prepared and characterised by spectroscopic methods in DMSO, methanol and PBS 7.4. The dominant sulfonated species was the disulfophthalocyanine. OTiPc(S)n is highly aggregated in PBS 7.4 solution and tends to partially monomerise, on addition of Triton X-100, while (Cl3)TaPc(S)n showed broadened spectra in all solvents and was not affected by Triton X-100. The absorption and excitation spectra of OTiPc(S)n are similar and are mirror images of their emission spectra in DMSO, but differ in PBS and methanol. The fluorescence quantum yields (ϕF) and lifetimes (τF) were larger in DMSO than in methanol. In PBS 7.4, however, the ϕF and τF values were significantly smaller for OTiPc(S)n, which is typical of aggregated species. Gradual addition of the electron-acceptor MV2+ to solutions of MPc(S)n complexes resulted in the fluorescence quenching of complexes with higher quenching observed for OTiPc(S)n. The interaction of the MPc(S)n complexes with MV2+, and hence the stoichiometry and association constants are evaluated by means of Job method.
- Full Text:
- Date Issued: 2007
Spectroscopic characterization and photodynamic antimicrobial chemotherapy of phthalocyanine-silver triangular nanoprism conjugates when supported on asymmetric polymer membranes
- Mafukidze, Donovan M, Sindelo, Azole, Nyokong, Tebello
- Authors: Mafukidze, Donovan M , Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186927 , vital:44548 , xlink:href="https://doi.org/10.1016/j.saa.2019.04.054"
- Description: Silver triangular nanoprisms were synthesized and conjugated to zinc (ZnPc) and indium (InPc) phthalocyanines prior to embedding in asymmetric membranes. Conjugation of nanoparticles increased triplet state and singlet oxygen quantum yields of the phthalocyanines as well as enhancing photodynamic antimicrobial chemotherapy (PACT) activity against bacteria (S. aureus). The ZnPc derivative showed higher PACT activity when compared to the InPc, possibly due to degradation of the latter in aqueous media.
- Full Text:
- Date Issued: 2019
- Authors: Mafukidze, Donovan M , Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186927 , vital:44548 , xlink:href="https://doi.org/10.1016/j.saa.2019.04.054"
- Description: Silver triangular nanoprisms were synthesized and conjugated to zinc (ZnPc) and indium (InPc) phthalocyanines prior to embedding in asymmetric membranes. Conjugation of nanoparticles increased triplet state and singlet oxygen quantum yields of the phthalocyanines as well as enhancing photodynamic antimicrobial chemotherapy (PACT) activity against bacteria (S. aureus). The ZnPc derivative showed higher PACT activity when compared to the InPc, possibly due to degradation of the latter in aqueous media.
- Full Text:
- Date Issued: 2019
Spectroscopic investigations and theoretical calculations of DABCO induced xanthene bridged self-assembled zinc (II) porphyrin dimer
- Xu, Li, Huang, Tingting, Liang, Xu, Mack, John, Harris, Jessica, Nyokong, Tebello, Li, Minzhi, Zhu, Weihua
- Authors: Xu, Li , Huang, Tingting , Liang, Xu , Mack, John , Harris, Jessica , Nyokong, Tebello , Li, Minzhi , Zhu, Weihua
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240732 , vital:50866 , xlink:href="https://doi.org/10.1142/S1088424616500231"
- Description: An in-depth study of the electronic structure of a 1,4-diazabicyclo[2.2.2]octane (DABCO) induced molecular self-assembled xanthene-bridged and amide-bonded porphyrin dimer is reported. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations are used to identify trends in the optical spectroscopic properties. B3LYP geometry optimization predicts the formation of an almost perfectly eclipsed structure with respect to the two porphyrin rings with the analogous pyrrole nitrogens separated by 7.7–8.1 Å. The observed distinctive derivative-shaped band morphology of the pseudo-Faraday-A11 terms in the MCD spectra has been used to identify the main electronic Q and B-bands and to validate the TD-DFT calculations. The absence of a discernible splitting of the redox steps or a quenching of the fluorescence demonstrates that there is no significant exciton coupling between the two porphyrin rings.
- Full Text:
- Date Issued: 2016
- Authors: Xu, Li , Huang, Tingting , Liang, Xu , Mack, John , Harris, Jessica , Nyokong, Tebello , Li, Minzhi , Zhu, Weihua
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240732 , vital:50866 , xlink:href="https://doi.org/10.1142/S1088424616500231"
- Description: An in-depth study of the electronic structure of a 1,4-diazabicyclo[2.2.2]octane (DABCO) induced molecular self-assembled xanthene-bridged and amide-bonded porphyrin dimer is reported. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations are used to identify trends in the optical spectroscopic properties. B3LYP geometry optimization predicts the formation of an almost perfectly eclipsed structure with respect to the two porphyrin rings with the analogous pyrrole nitrogens separated by 7.7–8.1 Å. The observed distinctive derivative-shaped band morphology of the pseudo-Faraday-A11 terms in the MCD spectra has been used to identify the main electronic Q and B-bands and to validate the TD-DFT calculations. The absence of a discernible splitting of the redox steps or a quenching of the fluorescence demonstrates that there is no significant exciton coupling between the two porphyrin rings.
- Full Text:
- Date Issued: 2016
Spectroscopic studies of nanostructures of negatively charged free base porphyrin and positively charged tin porphyrins
- George, Reama C, Egharevba, Gabriel O, Nyokong, Tebello
- Authors: George, Reama C , Egharevba, Gabriel O , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261661 , vital:53432 , xlink:href="https://doi.org/10.1016/j.poly.2010.01.028"
- Description: Spectroscopic studies were carried out on the homoaggregates of negatively charged free base meso-tetraphenylsulfonated porphyrin ([H2TPPS4]4−) and heteroaggregates of a mixture of protonated ([H4TPPS4]2−) and tin meso-tetra (N-methyl-4-pyridyl) porphyrin ([SnTMPyP]4+). The spectroscopic studies were done to determine the optimal conditions required for the fabrication of porphyrin nanorods by ionic self assembly of two oppositely charged porphyrins. In addition, the various spectral changes of [H4TPPS4]2− with concurrent change in pH and concentration are also investigated. In acid media at pH more than 3, and at concentrations less than 1 × 10−5 M, [H4TPPS4]2− molecules form J aggregates. A mixture of [H4TPPS4]2− and [SnTMPyP]4+ forms heteroaggregates of the J type in acid media. At pH’s 2 to 3, the optimum ratio for the formation of J aggregates is 3:1 and for pH 1, the optimum ratio is 2:1. Transmission electron microscope images of the nanostructures formed show that they are of cylindrical shape.
- Full Text:
- Date Issued: 2010
- Authors: George, Reama C , Egharevba, Gabriel O , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261661 , vital:53432 , xlink:href="https://doi.org/10.1016/j.poly.2010.01.028"
- Description: Spectroscopic studies were carried out on the homoaggregates of negatively charged free base meso-tetraphenylsulfonated porphyrin ([H2TPPS4]4−) and heteroaggregates of a mixture of protonated ([H4TPPS4]2−) and tin meso-tetra (N-methyl-4-pyridyl) porphyrin ([SnTMPyP]4+). The spectroscopic studies were done to determine the optimal conditions required for the fabrication of porphyrin nanorods by ionic self assembly of two oppositely charged porphyrins. In addition, the various spectral changes of [H4TPPS4]2− with concurrent change in pH and concentration are also investigated. In acid media at pH more than 3, and at concentrations less than 1 × 10−5 M, [H4TPPS4]2− molecules form J aggregates. A mixture of [H4TPPS4]2− and [SnTMPyP]4+ forms heteroaggregates of the J type in acid media. At pH’s 2 to 3, the optimum ratio for the formation of J aggregates is 3:1 and for pH 1, the optimum ratio is 2:1. Transmission electron microscope images of the nanostructures formed show that they are of cylindrical shape.
- Full Text:
- Date Issued: 2010
Spectroscopic studies of the interaction of cobalt (II) N, N', N ″, N‴-tetramethyltetra-3, 4-pyridinoporphyrazine with amino acids and nitrogen oxides
- Thamae, Mamothibe A, Nyokong, Tebello
- Authors: Thamae, Mamothibe A , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291617 , vital:56892 , xlink:href="https://doi.org/10.1002/jpp.551"
- Description: The interaction of histidine, cysteine, NO and nitrite with cobalt(II) N,N',N″,N‴-tetramethyltetra-3,4-tetrapyridinoporphyrazine ([CoIItmtppa]4+) is reported. Metal-based autoreduction of [CoIItmtppa]4+ occurs with the formation of the [CoItmtppa(-2)]3+ species in the presence of histidine and cysteine. Kinetic data for the auto reduction of [CoIItmtppa]4+ in the presence of these amino acids gave the rate constants kf = 2.1 × 101 and 2.8 dm3 mol-1 s-1, for cysteine and histidine, respectively. One molecule of NO or nitrite was found to coordinate to the [CoIItmtppa]4+ species. The equilibrium and rate constants for the coordination of the nitric oxide were K = 2.3 × 104dm3mol-1 and kf = 7.5 dm3mol-1s-1, respectively. The coordination of nitrite to [CoIItmtppa]4+ occurred with an equilibrium constant of K = 2.0 × 102dm3mol-1 and a rate constant of kf = 4.0 × 10-3dm3mol-1s-1. There was no evidence for the coordination of two molecules of nitrite to the [CoIItmtppa]4+ species.
- Full Text:
- Date Issued: 2001
- Authors: Thamae, Mamothibe A , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291617 , vital:56892 , xlink:href="https://doi.org/10.1002/jpp.551"
- Description: The interaction of histidine, cysteine, NO and nitrite with cobalt(II) N,N',N″,N‴-tetramethyltetra-3,4-tetrapyridinoporphyrazine ([CoIItmtppa]4+) is reported. Metal-based autoreduction of [CoIItmtppa]4+ occurs with the formation of the [CoItmtppa(-2)]3+ species in the presence of histidine and cysteine. Kinetic data for the auto reduction of [CoIItmtppa]4+ in the presence of these amino acids gave the rate constants kf = 2.1 × 101 and 2.8 dm3 mol-1 s-1, for cysteine and histidine, respectively. One molecule of NO or nitrite was found to coordinate to the [CoIItmtppa]4+ species. The equilibrium and rate constants for the coordination of the nitric oxide were K = 2.3 × 104dm3mol-1 and kf = 7.5 dm3mol-1s-1, respectively. The coordination of nitrite to [CoIItmtppa]4+ occurred with an equilibrium constant of K = 2.0 × 102dm3mol-1 and a rate constant of kf = 4.0 × 10-3dm3mol-1s-1. There was no evidence for the coordination of two molecules of nitrite to the [CoIItmtppa]4+ species.
- Full Text:
- Date Issued: 2001
Spontaneous charge transfer between zinc tetramethyl-tetra-2, 3-pyridinoporphyrazine and CdTe and ZnS quantum dots
- Moeno, Sharon, Idowu, Mopelola, Nyokong, Tebello
- Authors: Moeno, Sharon , Idowu, Mopelola , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265997 , vital:53908 , xlink:href="https://doi.org/10.1016/j.ica.2008.02.048"
- Description: Zinc tetramethyl-tetra-2,3-pyridinoporphyrazine (ZnTmtppa(-2)) gets reduced to the ZnTmtppa(-3) species on interaction with CdTe QDs capped with 2-mercaptoethanol (2-ME) or thioglycolic acid (TGA) and ZnS QDs capped with 2-ME. The interaction occurs without photolysis. The fluorescence of the QDs is quenched by ZnTmtppa resulting in large quenching constants. Binding of ZnTmtppa to QDs occurs with two molecules of the former binding to the latter.
- Full Text:
- Date Issued: 2008
- Authors: Moeno, Sharon , Idowu, Mopelola , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265997 , vital:53908 , xlink:href="https://doi.org/10.1016/j.ica.2008.02.048"
- Description: Zinc tetramethyl-tetra-2,3-pyridinoporphyrazine (ZnTmtppa(-2)) gets reduced to the ZnTmtppa(-3) species on interaction with CdTe QDs capped with 2-mercaptoethanol (2-ME) or thioglycolic acid (TGA) and ZnS QDs capped with 2-ME. The interaction occurs without photolysis. The fluorescence of the QDs is quenched by ZnTmtppa resulting in large quenching constants. Binding of ZnTmtppa to QDs occurs with two molecules of the former binding to the latter.
- Full Text:
- Date Issued: 2008
Spotlight on research: 50 years of Pharmaceutical Sciences Research Excellence Faculty of Pharmacy Rhodes University
- Authors: Walker, Roderick B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184243 , vital:44193 , xlink:href="https://hdl.handle.net/10520/EJC81478"
- Description: This year, the Faculty of Pharmacy at Rhodes University is celebrating its 50th Anniversary. Over 2000 BPharm, 33 BSc honours, 65 MSc and 27 PhD degrees have been conferred since the Faculty’s inception. The diverse research activities and dedicated academic staff have ensured that the Faculty of Pharmacy has high visibility with respect to research outputs, as is evidenced by the appointment of various members of staff to national and international research, regulatory and professional committees, as well as to serving on the editorial boards of a number of international journals. In addition, staff regularly publish in international and local peer-reviewed journals and present their research findings at international and local conferences.
- Full Text:
- Date Issued: 2006
- Authors: Walker, Roderick B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184243 , vital:44193 , xlink:href="https://hdl.handle.net/10520/EJC81478"
- Description: This year, the Faculty of Pharmacy at Rhodes University is celebrating its 50th Anniversary. Over 2000 BPharm, 33 BSc honours, 65 MSc and 27 PhD degrees have been conferred since the Faculty’s inception. The diverse research activities and dedicated academic staff have ensured that the Faculty of Pharmacy has high visibility with respect to research outputs, as is evidenced by the appointment of various members of staff to national and international research, regulatory and professional committees, as well as to serving on the editorial boards of a number of international journals. In addition, staff regularly publish in international and local peer-reviewed journals and present their research findings at international and local conferences.
- Full Text:
- Date Issued: 2006
St. Petersburg
- Authors: Krueger, Anton
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229818 , vital:49713 , xlink:href="https://hdl.handle.net/10520/EJC47812"
- Full Text:
- Date Issued: 2009
- Authors: Krueger, Anton
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229818 , vital:49713 , xlink:href="https://hdl.handle.net/10520/EJC47812"
- Full Text:
- Date Issued: 2009
Stability indicating HPLC-ECD method for the analysis of clarithromycin in pharmaceutical dosage forms: Method scaling versus re-validation.
- Makoni, Pedzisai A, Chikukwa, Mellisa, Khamanga, Sandile M, Walker, Roderick B
- Authors: Makoni, Pedzisai A , Chikukwa, Mellisa , Khamanga, Sandile M , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183387 , vital:43984 , xlink:href="https://doi.org/10.3390/scipharm87040031"
- Description: An isocratic high-performance liquid chromatographic method using electrochemical detection (HPLC-ECD) for the quantitation of clarithromycin (CLA) was developed using Response Surface Methodology (RSM) based on a Central Composite Design (CCD). The method was validated using International Conference on Harmonization (ICH) guidelines with an analytical run time of 20 min. Method re-validation following a change in analytical column was successful in reducing the analytical run time to 13 min, decreasing solvent consumption thus facilitating environmental and financial sustainability. The applicability of using the United States Pharmacopeia (USP) method scaling approach in place of method re-validation using a column with a different L–designation to the original analytical column, was investigated. The scaled method met all USP system suitability requirements for resolution, tailing factor and % relative standard deviation (RSD). The re-validated and scaled method was successfully used to resolve CLA from manufacturing excipients in commercially available dosage forms. Although USP method scaling is only permitted for columns within the same L-designation, these data suggest that it may also be applicable to columns of different designation.
- Full Text:
- Date Issued: 2019
- Authors: Makoni, Pedzisai A , Chikukwa, Mellisa , Khamanga, Sandile M , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183387 , vital:43984 , xlink:href="https://doi.org/10.3390/scipharm87040031"
- Description: An isocratic high-performance liquid chromatographic method using electrochemical detection (HPLC-ECD) for the quantitation of clarithromycin (CLA) was developed using Response Surface Methodology (RSM) based on a Central Composite Design (CCD). The method was validated using International Conference on Harmonization (ICH) guidelines with an analytical run time of 20 min. Method re-validation following a change in analytical column was successful in reducing the analytical run time to 13 min, decreasing solvent consumption thus facilitating environmental and financial sustainability. The applicability of using the United States Pharmacopeia (USP) method scaling approach in place of method re-validation using a column with a different L–designation to the original analytical column, was investigated. The scaled method met all USP system suitability requirements for resolution, tailing factor and % relative standard deviation (RSD). The re-validated and scaled method was successfully used to resolve CLA from manufacturing excipients in commercially available dosage forms. Although USP method scaling is only permitted for columns within the same L-designation, these data suggest that it may also be applicable to columns of different designation.
- Full Text:
- Date Issued: 2019
Stable Covalent pH-Sensitive Metallophthalocyanines Thin Monolayer Films for Selective Detection of Neurotransmitters
- Idowu, Abosede Omowumi Atinuke
- Authors: Idowu, Abosede Omowumi Atinuke
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192922 , vital:45279
- Description: Thesis (PhD) -- Faculty of Humanities, Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Idowu, Abosede Omowumi Atinuke
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192922 , vital:45279
- Description: Thesis (PhD) -- Faculty of Humanities, Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
Stakeholder engagement in social enterprise: designing a sustainable business model for the ‘Food for Us’ mobile application
- Authors: Tantsi, Idah Thato
- Date: 2022-10
- Subjects: Business planning South Africa , Sustainability South Africa , Mobile apps South Africa , Social responsibility of business South Africa , Social entrepreneurship South Africa , Food for Us (Application software)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/317141 , vital:59904
- Description: This study aimed to develop a sustainable business model that is cognisant of the fundamental principles of social enterprises that can sustain the operation of the Food for Us mobile application that links farmers with buyers in Eastern and Western Cape, South Africa. The Food for Us mobile application lacks a supporting sustainable social business model to sustain its continued operations, hence the need to develop one. In the study, data was generated qualitatively underpinned by an interpretive paradigm, in three workshops guided by the Delphi method. A stakeholder salience model was applied to identify key stakeholders and their salience. Three key stakeholders, namely users (farmers and buyers), Experts (App developers) and the consortium were identified. The study concluded that developing a sustainable social, innovative business model requires substantive consultation with multiple stakeholders in society. Every stakeholder is important and possesses varying salience, hence stakeholder mapping is an important exercise. The study further concluded that financial sustainability and social inclusion are critical social enterprise elements to consider in the process. The undertaking to enhance financial sustainability opens an understanding on the importance of income streams, the key activities, and value propositions offered by the mobile application. The need to remain socially inclusive brings forth questioning of value propositions, accessibility, user friendliness towards stakeholder diversity and needs. The study offers a solution for the Food for Us mobile application in the form of a prototype which is ready for testing, and if desired results are achieved, this can enhance the much needed continued operations of the mobile application. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2022
- Full Text:
- Date Issued: 2022-10
- Authors: Tantsi, Idah Thato
- Date: 2022-10
- Subjects: Business planning South Africa , Sustainability South Africa , Mobile apps South Africa , Social responsibility of business South Africa , Social entrepreneurship South Africa , Food for Us (Application software)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/317141 , vital:59904
- Description: This study aimed to develop a sustainable business model that is cognisant of the fundamental principles of social enterprises that can sustain the operation of the Food for Us mobile application that links farmers with buyers in Eastern and Western Cape, South Africa. The Food for Us mobile application lacks a supporting sustainable social business model to sustain its continued operations, hence the need to develop one. In the study, data was generated qualitatively underpinned by an interpretive paradigm, in three workshops guided by the Delphi method. A stakeholder salience model was applied to identify key stakeholders and their salience. Three key stakeholders, namely users (farmers and buyers), Experts (App developers) and the consortium were identified. The study concluded that developing a sustainable social, innovative business model requires substantive consultation with multiple stakeholders in society. Every stakeholder is important and possesses varying salience, hence stakeholder mapping is an important exercise. The study further concluded that financial sustainability and social inclusion are critical social enterprise elements to consider in the process. The undertaking to enhance financial sustainability opens an understanding on the importance of income streams, the key activities, and value propositions offered by the mobile application. The need to remain socially inclusive brings forth questioning of value propositions, accessibility, user friendliness towards stakeholder diversity and needs. The study offers a solution for the Food for Us mobile application in the form of a prototype which is ready for testing, and if desired results are achieved, this can enhance the much needed continued operations of the mobile application. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2022
- Full Text:
- Date Issued: 2022-10
Stakeholder relationship management and the perception of trust: a case study of a salient stakeholder
- Authors: Chambers, Craig Brian
- Date: 2022-06
- Subjects: Stakeholder management South Africa Sundays River (Eastern Cape) , Stakeholder theory , Trust , Industrial priorities , Social capital (Sociology)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419060 , vital:71612
- Description: Trust is an essential aspect in developing meaningful relationships between firms and their stakeholders. Mayer, Davis and Schoorman (1995, p.709) define trust as “the willingness of a party to be vulnerable to the actions of another party based on the expectation that the other party will perform a particular action important to the trustor irrespective of the ability to monitor or control that other party”. This study took the form of an explanatory case study that focussed on an interaction between a firm and a salient stakeholder and attempted to explain how this interaction influenced the perceived trustworthiness of the firm in stakeholders that were observing the interaction. The study attempted to add to the work of Crane (2020), whose research had focussed on stakeholder connectedness, and specifically how this could be utilized by firms interacting with stakeholders to engender trust in a wider group of stakeholders. The research aimed to evaluate how the Sterile Insect Release programme, operating by the firm in the Sunday’s River Valley, was given a second chance through engagement with a salient stakeholder and how the interaction was observed by a wider group of stakeholders leading to perceived stakeholder trustworthiness and social capital. The study had five objectives, namely to; (1) analyse how a firm’s ability, benevolence, and integrity enables (or does not engender) the development of the firm’s trustworthiness amongst its stakeholders; (2) analyse how the firm’s engagement with a salient stakeholder enables (or does not engender) increased levels of trustworthiness in the firm by the stakeholders that are observing its interaction with a salient stakeholder; (3) analyse the benefits of social capital gained through increased levels of stakeholder trust; (4) identify good practice guidelines for firm engagement with salient stakeholders to ensure the correct cues are portrayed to observing stakeholders for the development of the trustworthiness of the firm; and (5) make recommendations related to management practices that will support the development of trust. The research adopted a qualitative approach and data were collected through semi-structured interviews with three groups of stakeholders that were present at the meeting. A review of the literature was undertaken to identify various propositions for the research and from which a theory-driven coding memo was developed. The derived propositions were as follows: (1) observing a firm’s engagement with a single salient stakeholder will provide cues to observing stakeholders about the trustworthiness of the firm, and (2) perceptions of a firm’s trustworthiness will result in increased social capital between the firm and its stakeholders. The first proposition was divided into three sub-propositions for the study which stated; (a) observing a firm’s engagement with a single salient stakeholder will provide cues to observing stakeholders about the ability of the firm; (b) observing a firm’s engagement with a single salient stakeholder will provide cues to observing stakeholders about the benevolence of the firm; and (c) observing a firm’s engagement with a single salient stakeholder will provide cues to observing stakeholders about the integrity of the firm. From the literature analysis, various themes were identified which include, observed interactions, ability, benevolence, integrity, trustworthiness, and increased social capital. The research findings confirmed the propositions as being relevant to the case study. The findings confirmed that ability, benevolence, and integrity are key attributes in portraying trustworthiness when interacting with a salient stakeholder. All three attributes were noted by the interviewees as being important to observing stakeholders in the development of trust in a firm, although ability and integrity were found to be the dominant attributes in this case study. The findings did present some evidence that an increased level of perceived trustworthiness in the firm did positively influence the levels of social capital, however, this was not a common theme among all the interviewees. In the light of these findings, it is recommended that firms utilize stakeholder models to identify salient stakeholders that are influential within the markets in which they operate. The firm should actively pursue a strong relationship with these stakeholders, and further attempt to generate opportunities to interact with these stakeholders in a public forum where stakeholder connectedness could be utilized to develop perceived trust in the wider group of stakeholders. The firm should focus on open, honest, and transparent communication which are key aspects for portraying the attributes of ability, benevolence, and integrity. The study addresses a gap in the trust literature at a stakeholder level and therefore has contributed to the trust literature by addressing how the connectedness between stakeholders can lead to trust in a wider group of stakeholders by increasing efficiency during these interactions and utilizing situational circumstances to build social capital. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2023
- Full Text:
- Date Issued: 2022-06
- Authors: Chambers, Craig Brian
- Date: 2022-06
- Subjects: Stakeholder management South Africa Sundays River (Eastern Cape) , Stakeholder theory , Trust , Industrial priorities , Social capital (Sociology)
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419060 , vital:71612
- Description: Trust is an essential aspect in developing meaningful relationships between firms and their stakeholders. Mayer, Davis and Schoorman (1995, p.709) define trust as “the willingness of a party to be vulnerable to the actions of another party based on the expectation that the other party will perform a particular action important to the trustor irrespective of the ability to monitor or control that other party”. This study took the form of an explanatory case study that focussed on an interaction between a firm and a salient stakeholder and attempted to explain how this interaction influenced the perceived trustworthiness of the firm in stakeholders that were observing the interaction. The study attempted to add to the work of Crane (2020), whose research had focussed on stakeholder connectedness, and specifically how this could be utilized by firms interacting with stakeholders to engender trust in a wider group of stakeholders. The research aimed to evaluate how the Sterile Insect Release programme, operating by the firm in the Sunday’s River Valley, was given a second chance through engagement with a salient stakeholder and how the interaction was observed by a wider group of stakeholders leading to perceived stakeholder trustworthiness and social capital. The study had five objectives, namely to; (1) analyse how a firm’s ability, benevolence, and integrity enables (or does not engender) the development of the firm’s trustworthiness amongst its stakeholders; (2) analyse how the firm’s engagement with a salient stakeholder enables (or does not engender) increased levels of trustworthiness in the firm by the stakeholders that are observing its interaction with a salient stakeholder; (3) analyse the benefits of social capital gained through increased levels of stakeholder trust; (4) identify good practice guidelines for firm engagement with salient stakeholders to ensure the correct cues are portrayed to observing stakeholders for the development of the trustworthiness of the firm; and (5) make recommendations related to management practices that will support the development of trust. The research adopted a qualitative approach and data were collected through semi-structured interviews with three groups of stakeholders that were present at the meeting. A review of the literature was undertaken to identify various propositions for the research and from which a theory-driven coding memo was developed. The derived propositions were as follows: (1) observing a firm’s engagement with a single salient stakeholder will provide cues to observing stakeholders about the trustworthiness of the firm, and (2) perceptions of a firm’s trustworthiness will result in increased social capital between the firm and its stakeholders. The first proposition was divided into three sub-propositions for the study which stated; (a) observing a firm’s engagement with a single salient stakeholder will provide cues to observing stakeholders about the ability of the firm; (b) observing a firm’s engagement with a single salient stakeholder will provide cues to observing stakeholders about the benevolence of the firm; and (c) observing a firm’s engagement with a single salient stakeholder will provide cues to observing stakeholders about the integrity of the firm. From the literature analysis, various themes were identified which include, observed interactions, ability, benevolence, integrity, trustworthiness, and increased social capital. The research findings confirmed the propositions as being relevant to the case study. The findings confirmed that ability, benevolence, and integrity are key attributes in portraying trustworthiness when interacting with a salient stakeholder. All three attributes were noted by the interviewees as being important to observing stakeholders in the development of trust in a firm, although ability and integrity were found to be the dominant attributes in this case study. The findings did present some evidence that an increased level of perceived trustworthiness in the firm did positively influence the levels of social capital, however, this was not a common theme among all the interviewees. In the light of these findings, it is recommended that firms utilize stakeholder models to identify salient stakeholders that are influential within the markets in which they operate. The firm should actively pursue a strong relationship with these stakeholders, and further attempt to generate opportunities to interact with these stakeholders in a public forum where stakeholder connectedness could be utilized to develop perceived trust in the wider group of stakeholders. The firm should focus on open, honest, and transparent communication which are key aspects for portraying the attributes of ability, benevolence, and integrity. The study addresses a gap in the trust literature at a stakeholder level and therefore has contributed to the trust literature by addressing how the connectedness between stakeholders can lead to trust in a wider group of stakeholders by increasing efficiency during these interactions and utilizing situational circumstances to build social capital. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2023
- Full Text:
- Date Issued: 2022-06
Stancetaking by university students writing in English as a second language/ non-native language / non- native language: A case of students at Solusi University, Zimbabwe
- Chikara, Tendai Owen https://orcid.org/0000-0003-2546-7128
- Authors: Chikara, Tendai Owen https://orcid.org/0000-0003-2546-7128
- Date: 2021-05
- Subjects: Language and languages -- Style , Discourse analysis
- Language: English
- Type: Doctoral theses
- Identifier: http://hdl.handle.net/10353/22283 , vital:52013
- Description: The thrust of the study was to investigate the stancetaking strategies by English Second Language (ESL)/ Non‐Native Language learners undertaking undergraduate studies at one university in Zimbabwe. The learners in the study came from a variety of backgrounds but shared one common feature which was the fact that they used English as a Second Language/ Non‐native language/Non‐Native Language. Using a case study approach, the study interviewed these ESL users as well as analysed their essays to establish how the learners used metadiscourse markers to communicate stance. Using insights from Systemic Functional Linguistics (SFL) theory, the study sought to establish how the language of appraisal was used in the learners’ essays. Findings indicate that learners had a superficial appreciation of the academic writing genre and thus failed to use metadiscourse markers or resources of appraisal effectively to communicate stance. Differences were noted in the manner that stance was communicated between different faculties and possible explanations were offered for such findings. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2021
- Full Text:
- Date Issued: 2021-05
- Authors: Chikara, Tendai Owen https://orcid.org/0000-0003-2546-7128
- Date: 2021-05
- Subjects: Language and languages -- Style , Discourse analysis
- Language: English
- Type: Doctoral theses
- Identifier: http://hdl.handle.net/10353/22283 , vital:52013
- Description: The thrust of the study was to investigate the stancetaking strategies by English Second Language (ESL)/ Non‐Native Language learners undertaking undergraduate studies at one university in Zimbabwe. The learners in the study came from a variety of backgrounds but shared one common feature which was the fact that they used English as a Second Language/ Non‐native language/Non‐Native Language. Using a case study approach, the study interviewed these ESL users as well as analysed their essays to establish how the learners used metadiscourse markers to communicate stance. Using insights from Systemic Functional Linguistics (SFL) theory, the study sought to establish how the language of appraisal was used in the learners’ essays. Findings indicate that learners had a superficial appreciation of the academic writing genre and thus failed to use metadiscourse markers or resources of appraisal effectively to communicate stance. Differences were noted in the manner that stance was communicated between different faculties and possible explanations were offered for such findings. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2021
- Full Text:
- Date Issued: 2021-05
Standards for the admission of forensic scientific evidence in criminal trials through an expert: Lessons and guidelines for South Africa
- Chetty, Nasholan https://orcid.org/0000-0002-7053-5831
- Authors: Chetty, Nasholan https://orcid.org/0000-0002-7053-5831
- Date: 2022-01
- Subjects: Evidence, Expert , Forensic sciences , Crime scene searches
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22467 , vital:52324
- Description: Forensic evidence has always captured the imagination of the public and legal fraternity since science entered the courtroom. The first case of forensic science was heard in the matter of John Boodle in 1832, and criminal courts have now come accustomed to hearing a variety of matters that have some form of forensic science evidence in them. Television shows like Crime Scene Investigation and Making a Murderer has heightened the expectation that is placed on the sciences and the ease of which a conviction can be secured or a suspect apprehended. The spate of wrongful convictions that have been overturned, particularly in the United States of America has raised serious questions regarding the use of forensic evidence in courts. Moreover, the people “in-charge” or the so-called experts for providing this analysis’s have come under intense scrutiny. Many reports have been compiled after investigations were conducted into the state of expert evidence in those various jurisdictions. The use of an expert to provide critical details regarding aspects of a crime that goes beyond the ordinary education of presiding officers and legal practitioners has posed to the court, many questions as to how they are being used and whether their evidence should be used. The use of an expert is not new to the South African legal system, and the same can be said for many foreign jurisdictions, but the problem now experienced by courts is whether these experts are in-fact “experts” and whether the information conveyed to the court can be relied upon especially if the evidence is of a scientific nature. An investigation into how expert evidence is presented and evaluated in South African criminal courts will reveal many appealing aspects regarding the development of how an expert is used and how they should be used as well as how their evidence should be evaluated. , Thesis (PhD) -- Faculty of Law, 2022
- Full Text:
- Date Issued: 2022-01
- Authors: Chetty, Nasholan https://orcid.org/0000-0002-7053-5831
- Date: 2022-01
- Subjects: Evidence, Expert , Forensic sciences , Crime scene searches
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22467 , vital:52324
- Description: Forensic evidence has always captured the imagination of the public and legal fraternity since science entered the courtroom. The first case of forensic science was heard in the matter of John Boodle in 1832, and criminal courts have now come accustomed to hearing a variety of matters that have some form of forensic science evidence in them. Television shows like Crime Scene Investigation and Making a Murderer has heightened the expectation that is placed on the sciences and the ease of which a conviction can be secured or a suspect apprehended. The spate of wrongful convictions that have been overturned, particularly in the United States of America has raised serious questions regarding the use of forensic evidence in courts. Moreover, the people “in-charge” or the so-called experts for providing this analysis’s have come under intense scrutiny. Many reports have been compiled after investigations were conducted into the state of expert evidence in those various jurisdictions. The use of an expert to provide critical details regarding aspects of a crime that goes beyond the ordinary education of presiding officers and legal practitioners has posed to the court, many questions as to how they are being used and whether their evidence should be used. The use of an expert is not new to the South African legal system, and the same can be said for many foreign jurisdictions, but the problem now experienced by courts is whether these experts are in-fact “experts” and whether the information conveyed to the court can be relied upon especially if the evidence is of a scientific nature. An investigation into how expert evidence is presented and evaluated in South African criminal courts will reveal many appealing aspects regarding the development of how an expert is used and how they should be used as well as how their evidence should be evaluated. , Thesis (PhD) -- Faculty of Law, 2022
- Full Text:
- Date Issued: 2022-01
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:
State Antiquity and Early Agricultural transition as Deep economic roots in Africa
- Authors: Fani, Sisipho
- Date: 2022-04
- Subjects: Agriculture -- Economic aspects , Agriculture -- Early works to 1800
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57643 , vital:58189
- 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 (MA) -- Faculty of Business and Economic science , 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Fani, Sisipho
- Date: 2022-04
- Subjects: Agriculture -- Economic aspects , Agriculture -- Early works to 1800
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57643 , vital:58189
- 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 (MA) -- Faculty of Business and Economic science , 2022
- Full Text:
- Date Issued: 2022-04
Statistical and Mathematical Learning: an application to fraud detection and prevention
- Authors: Hamlomo, Sisipho
- Date: 2022-04-06
- Subjects: Credit card fraud , Bootstrap (Statistics) , Support vector machines , Neural networks (Computer science) , Decision trees , Machine learning , Cross-validation , Imbalanced data
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/233795 , vital:50128
- Description: Credit card fraud is an ever-growing problem. There has been a rapid increase in the rate of fraudulent activities in recent years resulting in a considerable loss to several organizations, companies, and government agencies. Many researchers have focused on detecting fraudulent behaviours early using advanced machine learning techniques. However, credit card fraud detection is not a straightforward task since fraudulent behaviours usually differ for each attempt and the dataset is highly imbalanced, that is, the frequency of non-fraudulent cases outnumbers the frequency of fraudulent cases. In the case of the European credit card dataset, we have a ratio of approximately one fraudulent case to five hundred and seventy-eight non-fraudulent cases. Different methods were implemented to overcome this problem, namely random undersampling, one-sided sampling, SMOTE combined with Tomek links and parameter tuning. Predictive classifiers, namely logistic regression, decision trees, k-nearest neighbour, support vector machine and multilayer perceptrons, are applied to predict if a transaction is fraudulent or non-fraudulent. The model's performance is evaluated based on recall, precision, F1-score, the area under receiver operating characteristics curve, geometric mean and Matthew correlation coefficient. The results showed that the logistic regression classifier performed better than other classifiers except when the dataset was oversampled. , Thesis (MSc) -- Faculty of Science, Statistics, 2022
- Full Text:
- Date Issued: 2022-04-06
- Authors: Hamlomo, Sisipho
- Date: 2022-04-06
- Subjects: Credit card fraud , Bootstrap (Statistics) , Support vector machines , Neural networks (Computer science) , Decision trees , Machine learning , Cross-validation , Imbalanced data
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/233795 , vital:50128
- Description: Credit card fraud is an ever-growing problem. There has been a rapid increase in the rate of fraudulent activities in recent years resulting in a considerable loss to several organizations, companies, and government agencies. Many researchers have focused on detecting fraudulent behaviours early using advanced machine learning techniques. However, credit card fraud detection is not a straightforward task since fraudulent behaviours usually differ for each attempt and the dataset is highly imbalanced, that is, the frequency of non-fraudulent cases outnumbers the frequency of fraudulent cases. In the case of the European credit card dataset, we have a ratio of approximately one fraudulent case to five hundred and seventy-eight non-fraudulent cases. Different methods were implemented to overcome this problem, namely random undersampling, one-sided sampling, SMOTE combined with Tomek links and parameter tuning. Predictive classifiers, namely logistic regression, decision trees, k-nearest neighbour, support vector machine and multilayer perceptrons, are applied to predict if a transaction is fraudulent or non-fraudulent. The model's performance is evaluated based on recall, precision, F1-score, the area under receiver operating characteristics curve, geometric mean and Matthew correlation coefficient. The results showed that the logistic regression classifier performed better than other classifiers except when the dataset was oversampled. , Thesis (MSc) -- Faculty of Science, Statistics, 2022
- Full Text:
- Date Issued: 2022-04-06