Studies directed towards the synthesis of chromone carbaldehyde-derived HIV-1 protease inhibitors
- Authors: Molefe, Duduzile Mabel
- Date: 2008
- Subjects: Protease Inhibitors , HIV infections , HIV (Viruses) , AIDS (Disease) , Proteolytic enzymes , Heterocyclic compounds -- Derivatives , Chemical kinetics , Nuclear magnetic resonance spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4526 , http://hdl.handle.net/10962/d1015542
- Description: A series of chromone-3-carbaldehydes have been prepared using Vilsmeier-Haack methodology while a corresponding series of chromone-2-carbaldeydes have been synthesized via the Kostanecki-Robinson reaction. Baylis-Hillman reactions have been conducted on both series of chromone carbaldehydes using three different catalysts, viz., 1,4-diazabicyclo(2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec- 7-ene (DBU) and 3-hydroxyquinuclidine (3HQ), and acrylonitrile, methyl acrylate and methyl vinyl ketone as the activated alkenes. These reactions have typically (but not always!) afforded both normal Baylis-Hillman and dimeric products. Attention has also been given to the use of 1-methyl-2-pyrrolidine (1-NMP), an ionic liquid, to replace normal organic solvents, and it has been found that, in the presence of DABCO, chromone-3-carbaldehydes afford the dimeric products alone. Reactions of chromone-3-carbaldehydes with methyl vinyl ketone have yielded unexpected, novel adducts, which appear to arise from preferential attack at C(2) in the chromone nucleus. Research on chromone-2-carbaldeydes under Baylis-Hillman conditions has also resulted in the formation of some interesting products instead of the expected Baylis-Hillman adducts. The Baylis-Hillman products have been explored as substrates for aza-Michael reactions using various amino derivatives including protected amino acids in the presence of the tetrabutylammonium bromide (TBAB) and the ionic liquid, 3-butyl-1- methylimidazoleboranetetrafluoride (BmimBF₄), as catalysts. The aza-Michael products have been targeted as truncated ritonavir analogues for investigation as potential HIV -1 protease inhibitors, and representative compounds have been subjected to enzyme inhibition assays to explore the extent and type of inhibition. Lineweaver-Burk and Dixon plots have indicated competitive inhibition in one case as well as non-competitive inhibition in another, and the inhibition constants (Ki) have been compared with that of the ritonavir. Computer modelling studies have also been conducted on selected chromonecontaining derivatives, using the ACCELRYS Cerius² platform. Interactive docking of the chromone-containing ligands into the HIV -1 protease receptor site, using the Ligandfit module, has indicated the importance of hydrogen-bonding interactions mediated by bridging water molecules situated in the receptor cavity. NMR spectroscopy has been used to elucidate complex and competing mechanistic pathways involved in the Baylis-Hillman reactions of selected 2-nitrobenzaldehydes with MVK in the presence of DABCO - reactions which afford the normal BaylisHillman product, the MVK dimer and syn- and anti-Baylis-Hillman type diadducts. The kinetic data confirm the concomitant operation of two pathways and reveal that, in the initial stage of the reaction, the product distribution is kinetically controlled, whereas in the latter stage, thermodynamic control results in the consumption of the normal Baylis-Hillman product and predominance of the anti-diadduct.
- Full Text:
- Date Issued: 2008
- Authors: Molefe, Duduzile Mabel
- Date: 2008
- Subjects: Protease Inhibitors , HIV infections , HIV (Viruses) , AIDS (Disease) , Proteolytic enzymes , Heterocyclic compounds -- Derivatives , Chemical kinetics , Nuclear magnetic resonance spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4526 , http://hdl.handle.net/10962/d1015542
- Description: A series of chromone-3-carbaldehydes have been prepared using Vilsmeier-Haack methodology while a corresponding series of chromone-2-carbaldeydes have been synthesized via the Kostanecki-Robinson reaction. Baylis-Hillman reactions have been conducted on both series of chromone carbaldehydes using three different catalysts, viz., 1,4-diazabicyclo(2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec- 7-ene (DBU) and 3-hydroxyquinuclidine (3HQ), and acrylonitrile, methyl acrylate and methyl vinyl ketone as the activated alkenes. These reactions have typically (but not always!) afforded both normal Baylis-Hillman and dimeric products. Attention has also been given to the use of 1-methyl-2-pyrrolidine (1-NMP), an ionic liquid, to replace normal organic solvents, and it has been found that, in the presence of DABCO, chromone-3-carbaldehydes afford the dimeric products alone. Reactions of chromone-3-carbaldehydes with methyl vinyl ketone have yielded unexpected, novel adducts, which appear to arise from preferential attack at C(2) in the chromone nucleus. Research on chromone-2-carbaldeydes under Baylis-Hillman conditions has also resulted in the formation of some interesting products instead of the expected Baylis-Hillman adducts. The Baylis-Hillman products have been explored as substrates for aza-Michael reactions using various amino derivatives including protected amino acids in the presence of the tetrabutylammonium bromide (TBAB) and the ionic liquid, 3-butyl-1- methylimidazoleboranetetrafluoride (BmimBF₄), as catalysts. The aza-Michael products have been targeted as truncated ritonavir analogues for investigation as potential HIV -1 protease inhibitors, and representative compounds have been subjected to enzyme inhibition assays to explore the extent and type of inhibition. Lineweaver-Burk and Dixon plots have indicated competitive inhibition in one case as well as non-competitive inhibition in another, and the inhibition constants (Ki) have been compared with that of the ritonavir. Computer modelling studies have also been conducted on selected chromonecontaining derivatives, using the ACCELRYS Cerius² platform. Interactive docking of the chromone-containing ligands into the HIV -1 protease receptor site, using the Ligandfit module, has indicated the importance of hydrogen-bonding interactions mediated by bridging water molecules situated in the receptor cavity. NMR spectroscopy has been used to elucidate complex and competing mechanistic pathways involved in the Baylis-Hillman reactions of selected 2-nitrobenzaldehydes with MVK in the presence of DABCO - reactions which afford the normal BaylisHillman product, the MVK dimer and syn- and anti-Baylis-Hillman type diadducts. The kinetic data confirm the concomitant operation of two pathways and reveal that, in the initial stage of the reaction, the product distribution is kinetically controlled, whereas in the latter stage, thermodynamic control results in the consumption of the normal Baylis-Hillman product and predominance of the anti-diadduct.
- Full Text:
- Date Issued: 2008
Studies in marine diterpene chemistry
- Van Wyk, Albert Wynand Wincke
- Authors: Van Wyk, Albert Wynand Wincke
- Date: 2008
- Subjects: Natural products Diterpenes Mollusks Marine metabolites Chemical oceanography
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4354 , http://hdl.handle.net/10962/d1005019
- Description: This thesis comprises both a natural product investigation and a synthetic component. The natural product investigations are presented in Chapters Two and Three. In Chapter Two the isolation and spectroscopic identification of the new isocopalane diterpene 12S,13R,14Sisocopalan- 13-ol-12,14-diacetate (2.1) and two known 3-(14S)-isocopal-12-ene-15-oyl-1- acetyl-sn-glycerol (2.2) and 3-(14S)-isocopal-12-ene-15-oyl-2-acetyl-sn-glycerol (2.3) from a single, large, unidentified sub-Antarctic nudibranch, collected near Marion Island, approximately 2000 km south of Cape Town are described. Chapter Three discusses the isolation, spectroscopic structure elucidation and anti-oesophageal cancer activity (3.1-3.4 only) of two known labdane diterpenes 6β,7α-diacetoxylabda-8,13E-dien-15-ol (3.1) and 2α,6β,7α-triacetoxylabda-8,13E-dien-15-ol (3.2) and one new 6β,7α,15-triacetoxylabda 8,13E-diene (3.3), as well as new 3α,11-dihydroxy-9,11-seco-cholest-4,7-dien-6,9-dione (3.4) and cholest 7-en-3,5,7-triol (3.5) from the endemic pulmonate mollusc, Trimusculus costatus. The absolute configuration of 3.2, and hence 3.1 and 3.3 (from biogenetic arguments) was determined through X-ray diffraction of a single crystal of the camphanate ester of 3.2. The absolute configuration of the secondary hydroxyl at C-3 of 3.4 was established using the Modified Mosher’s method. The synthetic component of the thesis commences in Chapter Four with the semi-synthesis of labdane diterpene nitriles 9α-cyano-15,16-epoxy-7β-hydroxylabda-13(16),14-dien-6-one (4.1), 9α-cyano-15,16-epoxy-7-hydroxylabda-7,13(16),14-trien-6-one (4.2) and 9α-cyano-15,16- epoxy-6β,7β dihydroxylabda-13(16),14-diene (4.3) from the terrestrial labdane diterpene, hispanolone (4.4). This work is an extension of previous synthetic studies directed towards the synthesis of T. costatus metabolites. Diterpenes 4.1-4.3 exhibited in planta activity against the economically important crop pathogens, Magnaporthea grisea and Puccinia recondita. Chapter Five describes the successful semi-synthesis of two isomeric marine molluscan labdane diterpene aldehyde metabolites, labd-13E-ene-8β-ol-15-al (5.1) and labd-13Z-ene- 8β-ol-15-al (5.2) from the commercially available, terrestrial plant derived, labdane diterpene manool (5.3). Diterpenes 5.1 and 5.2, originally isolated from the Mediterranean nudibranch,Pleurobranchaea meckelii and selected diterpenes arising from this synthesis were evaluated for their activity against an oesophageal cancer cell line (WHCO1). Chapter Six further develops the research discussed in Chapter Five, where ethyl 17-norabiet-13(15)-E-en-8β-ol- 16-oate (5.49) and ethyl 17-norabiet-13(15)-Z-en-8β-ol-16-oate (5.50) were first semisynthesized serendipitously. Based on their structural relationship to naturally occurring tricyclic diterpenes with anti-plasmodial activity, tricyclic diterpenes, 17-norpimaran-13α- ethoxy-8,16-olactone (6.6), 17-norisopimar-15-ene-8β,13β-diol (6.7), 17-norisopimarane- 8β,16-diol (6.8) and 17-norabiet-13(15)-ene-8β,16-diol (6.9) were semi-synthesized from the terrestrial labdane diterpene, 5.3, and critically evaluated for their antimalarial potential from parasite inhibition and haemolytic studies.
- Full Text:
- Date Issued: 2008
- Authors: Van Wyk, Albert Wynand Wincke
- Date: 2008
- Subjects: Natural products Diterpenes Mollusks Marine metabolites Chemical oceanography
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4354 , http://hdl.handle.net/10962/d1005019
- Description: This thesis comprises both a natural product investigation and a synthetic component. The natural product investigations are presented in Chapters Two and Three. In Chapter Two the isolation and spectroscopic identification of the new isocopalane diterpene 12S,13R,14Sisocopalan- 13-ol-12,14-diacetate (2.1) and two known 3-(14S)-isocopal-12-ene-15-oyl-1- acetyl-sn-glycerol (2.2) and 3-(14S)-isocopal-12-ene-15-oyl-2-acetyl-sn-glycerol (2.3) from a single, large, unidentified sub-Antarctic nudibranch, collected near Marion Island, approximately 2000 km south of Cape Town are described. Chapter Three discusses the isolation, spectroscopic structure elucidation and anti-oesophageal cancer activity (3.1-3.4 only) of two known labdane diterpenes 6β,7α-diacetoxylabda-8,13E-dien-15-ol (3.1) and 2α,6β,7α-triacetoxylabda-8,13E-dien-15-ol (3.2) and one new 6β,7α,15-triacetoxylabda 8,13E-diene (3.3), as well as new 3α,11-dihydroxy-9,11-seco-cholest-4,7-dien-6,9-dione (3.4) and cholest 7-en-3,5,7-triol (3.5) from the endemic pulmonate mollusc, Trimusculus costatus. The absolute configuration of 3.2, and hence 3.1 and 3.3 (from biogenetic arguments) was determined through X-ray diffraction of a single crystal of the camphanate ester of 3.2. The absolute configuration of the secondary hydroxyl at C-3 of 3.4 was established using the Modified Mosher’s method. The synthetic component of the thesis commences in Chapter Four with the semi-synthesis of labdane diterpene nitriles 9α-cyano-15,16-epoxy-7β-hydroxylabda-13(16),14-dien-6-one (4.1), 9α-cyano-15,16-epoxy-7-hydroxylabda-7,13(16),14-trien-6-one (4.2) and 9α-cyano-15,16- epoxy-6β,7β dihydroxylabda-13(16),14-diene (4.3) from the terrestrial labdane diterpene, hispanolone (4.4). This work is an extension of previous synthetic studies directed towards the synthesis of T. costatus metabolites. Diterpenes 4.1-4.3 exhibited in planta activity against the economically important crop pathogens, Magnaporthea grisea and Puccinia recondita. Chapter Five describes the successful semi-synthesis of two isomeric marine molluscan labdane diterpene aldehyde metabolites, labd-13E-ene-8β-ol-15-al (5.1) and labd-13Z-ene- 8β-ol-15-al (5.2) from the commercially available, terrestrial plant derived, labdane diterpene manool (5.3). Diterpenes 5.1 and 5.2, originally isolated from the Mediterranean nudibranch,Pleurobranchaea meckelii and selected diterpenes arising from this synthesis were evaluated for their activity against an oesophageal cancer cell line (WHCO1). Chapter Six further develops the research discussed in Chapter Five, where ethyl 17-norabiet-13(15)-E-en-8β-ol- 16-oate (5.49) and ethyl 17-norabiet-13(15)-Z-en-8β-ol-16-oate (5.50) were first semisynthesized serendipitously. Based on their structural relationship to naturally occurring tricyclic diterpenes with anti-plasmodial activity, tricyclic diterpenes, 17-norpimaran-13α- ethoxy-8,16-olactone (6.6), 17-norisopimar-15-ene-8β,13β-diol (6.7), 17-norisopimarane- 8β,16-diol (6.8) and 17-norabiet-13(15)-ene-8β,16-diol (6.9) were semi-synthesized from the terrestrial labdane diterpene, 5.3, and critically evaluated for their antimalarial potential from parasite inhibition and haemolytic studies.
- Full Text:
- Date Issued: 2008
Studies towards the synthesis of novel, coumarin-based HIV-1 protease inhibitors
- Authors: Rashamuse, Thompho Jason
- Date: 2008
- Subjects: Coumarins , Protease Inhibitors , HIV infections -- Treatment , HIV (Viruses) , AIDS (Disease) -- Treatment , Heterocyclic compounds -- Derivatives
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4359 , http://hdl.handle.net/10962/d1005024 , Coumarins , Protease Inhibitors , HIV infections -- Treatment , HIV (Viruses) , AIDS (Disease) -- Treatment , Heterocyclic compounds -- Derivatives
- Description: A series of the Baylis-Hillman adducts have been obtained by reacting protected O-benzylated and unprotected substituted salicylaldehydes with methyl acrylate or tertbutyl acrylate, respectively, using DABCO as catalyst. Treatment of the Baylis-Hillman adducts with HCl in a mixture of acetic acid and acetic anhydride afforded the corresponding 3-(chloromethyl)coumarin derivatives with yields of up to 94%. Similar use of HI afforded the corresponding 3-(iodomethyl)coumarins but, depending on the reaction time, the reduced 3-methyl analogues could also be obtained. Arbuzov reactions of the 3-(halomethyl)coumarin derivatives have been undertaken to afford 4-phosphorylated and 1’-phosphorylated derivatives, regioselectivity being dependent on the halide-leaving group. The 3-(chloromethyl)coumarin derivatives have been subjected to nucleophilic (SN) attack by benzylamine to give the corresponding 3- [(benzylamino)methyl]coumarin derivatives in yields of up to 74%. Further treatment of the 3-[(benzylamino)methyl]coumarin derivatives with chloroacetyl chloride afforded the chloroacetamide derivatives, which exhibit hindered rotation about the amine C(O)-N bond. The acetamide derivatives have also been subjected to Arbuzov reaction conditions to afford the phosphorylated derivatives in yields of up to 86%. In a preliminary modelling study, hydrolysed analogues of the synthesized phosphorylated derivatives have been docked into the active site of the HIV-1 protease enzyme using the Cerius-2 Ligandfit software module to provide an insight into potential receptor-ligand hydrogen bonding interactions.
- Full Text:
- Date Issued: 2008
- Authors: Rashamuse, Thompho Jason
- Date: 2008
- Subjects: Coumarins , Protease Inhibitors , HIV infections -- Treatment , HIV (Viruses) , AIDS (Disease) -- Treatment , Heterocyclic compounds -- Derivatives
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4359 , http://hdl.handle.net/10962/d1005024 , Coumarins , Protease Inhibitors , HIV infections -- Treatment , HIV (Viruses) , AIDS (Disease) -- Treatment , Heterocyclic compounds -- Derivatives
- Description: A series of the Baylis-Hillman adducts have been obtained by reacting protected O-benzylated and unprotected substituted salicylaldehydes with methyl acrylate or tertbutyl acrylate, respectively, using DABCO as catalyst. Treatment of the Baylis-Hillman adducts with HCl in a mixture of acetic acid and acetic anhydride afforded the corresponding 3-(chloromethyl)coumarin derivatives with yields of up to 94%. Similar use of HI afforded the corresponding 3-(iodomethyl)coumarins but, depending on the reaction time, the reduced 3-methyl analogues could also be obtained. Arbuzov reactions of the 3-(halomethyl)coumarin derivatives have been undertaken to afford 4-phosphorylated and 1’-phosphorylated derivatives, regioselectivity being dependent on the halide-leaving group. The 3-(chloromethyl)coumarin derivatives have been subjected to nucleophilic (SN) attack by benzylamine to give the corresponding 3- [(benzylamino)methyl]coumarin derivatives in yields of up to 74%. Further treatment of the 3-[(benzylamino)methyl]coumarin derivatives with chloroacetyl chloride afforded the chloroacetamide derivatives, which exhibit hindered rotation about the amine C(O)-N bond. The acetamide derivatives have also been subjected to Arbuzov reaction conditions to afford the phosphorylated derivatives in yields of up to 86%. In a preliminary modelling study, hydrolysed analogues of the synthesized phosphorylated derivatives have been docked into the active site of the HIV-1 protease enzyme using the Cerius-2 Ligandfit software module to provide an insight into potential receptor-ligand hydrogen bonding interactions.
- Full Text:
- Date Issued: 2008
Synthesis, photochemical and photophysical properties of gallium and indium phthalocyanine derivatives
- Authors: Chauke, Vongani Portia
- Date: 2008
- Subjects: Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4375 , http://hdl.handle.net/10962/d1005040 , Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Description: The syntheses of octasubstituted and unsusbstitituted Gallium(III) chloride and indium(III) chloride phthalocyanines (GaPc and InPc), their photophysical, photochemical and nonlinear optical parameters are hereby presented. The photocatalytic oxidation of 1-hexene using the synthesized GaPc and InPc complexes as well as electrochemical characterization is also presented in this thesis. Fluorescence quantum yields do not vary much among the four Ga complexes, except for complex 21c; therefore it was concluded that the effect of substituents is not significant among them. Solvents however, had an effect on the results. Lower Φ[subscript F] values were obtained in low viscosity solvents like toluene, relative to highly viscous solvents, such as DMSO. The triplet quantum yields were found to be lower in DMSO than in DMF and toluene. The rate constants for fluorescence, intersystem crossing and internal conversion as well as fluorescence and triplet lifetimes are reported. Photodegradation and singlet oxygen quantum yields have also been reported. There was no clear correlation between the latter parameters. It was however established that the four gallium MPcs were stable, within the allowed stability range for phthalocyanines. High quantum yields of triplet state (Φ[subscript T] ranging from 0.70 to 0.91 in dimethysulfoxide, DMSO) and singlet oxygen generation (Φ[subscript greek capital letter delta], ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50 to 60 μs were obtained in DMSO). Calculated non-linear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. The optical limiting threshold intensity (I[subscript lim]) values for the InPc and GaPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The octasubstituted were found to be better optical limiters. Photocatalytic oxidation of 1-hexene by GaPc (21a-c) and InPc (22a-c) derivatives is also presented. The photocatalytic oxidation products for 1-hexene were 1,2- epoxyhexane and 1-hexen-3-ol. The % conversion values of 1-hexene and % selectivity of 1,2-epoxyhexane were generally higher for InPc derivatives. Even though InPc derivatives showed better photocatalytic results than GaPc derivatives, the former were less stable relative to the latter. Both type I and type II mechanism were implicated in the photocatalysis mechanism.
- Full Text:
- Date Issued: 2008
- Authors: Chauke, Vongani Portia
- Date: 2008
- Subjects: Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4375 , http://hdl.handle.net/10962/d1005040 , Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Description: The syntheses of octasubstituted and unsusbstitituted Gallium(III) chloride and indium(III) chloride phthalocyanines (GaPc and InPc), their photophysical, photochemical and nonlinear optical parameters are hereby presented. The photocatalytic oxidation of 1-hexene using the synthesized GaPc and InPc complexes as well as electrochemical characterization is also presented in this thesis. Fluorescence quantum yields do not vary much among the four Ga complexes, except for complex 21c; therefore it was concluded that the effect of substituents is not significant among them. Solvents however, had an effect on the results. Lower Φ[subscript F] values were obtained in low viscosity solvents like toluene, relative to highly viscous solvents, such as DMSO. The triplet quantum yields were found to be lower in DMSO than in DMF and toluene. The rate constants for fluorescence, intersystem crossing and internal conversion as well as fluorescence and triplet lifetimes are reported. Photodegradation and singlet oxygen quantum yields have also been reported. There was no clear correlation between the latter parameters. It was however established that the four gallium MPcs were stable, within the allowed stability range for phthalocyanines. High quantum yields of triplet state (Φ[subscript T] ranging from 0.70 to 0.91 in dimethysulfoxide, DMSO) and singlet oxygen generation (Φ[subscript greek capital letter delta], ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50 to 60 μs were obtained in DMSO). Calculated non-linear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. The optical limiting threshold intensity (I[subscript lim]) values for the InPc and GaPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The octasubstituted were found to be better optical limiters. Photocatalytic oxidation of 1-hexene by GaPc (21a-c) and InPc (22a-c) derivatives is also presented. The photocatalytic oxidation products for 1-hexene were 1,2- epoxyhexane and 1-hexen-3-ol. The % conversion values of 1-hexene and % selectivity of 1,2-epoxyhexane were generally higher for InPc derivatives. Even though InPc derivatives showed better photocatalytic results than GaPc derivatives, the former were less stable relative to the latter. Both type I and type II mechanism were implicated in the photocatalysis mechanism.
- Full Text:
- Date Issued: 2008
Synthesis, photophysics and electrochemical study of tin macrocycles
- Authors: Khene, Mielie Samson
- Date: 2008
- Subjects: Electrochemistry , Photochemistry , Phthalocyanines , Macrocyclic compounds , Spectrum analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4376 , http://hdl.handle.net/10962/d1005041 , Electrochemistry , Photochemistry , Phthalocyanines , Macrocyclic compounds , Spectrum analysis
- Description: Three non-peripherally substituted tin(IV) macrocylic compounds, octahexylphthalocyaninato dichlorotin(IV) (35a), octahexyltetrabenzo-5,10,15-triazaporphyrinato dichlorotin(IV) (35b) and octadecylphthalocyaninato dichlorotin(IV) (35c) were synthesized and their photophysical and electrochemical behaviour studied. Complex (35b), containing a CH group in place of one of the aza nitrogen atom of the phthalocyanine core, shows a split Q band due to its lower symmetry. The triplet state quantum yields were found to be lower than would be expected on the basis of the heavy atom effect of tin as the central metal for phthalocyanine derivatives (35a and 35c). In contrast, (35b) shows a triplet quantum yield ΦT = 0.78. The triplet state lifetimes were solvent dependent, and were higher in THF than in toluene. Cyclic voltammetry and spectroelectrochemistry of the complexes revealed only ring based redox processes. This thesis also reports on the microwave syntheses of tetrasulphonated tin phthalocyanine and tetrasulphonated tin α,β,γ-tetrabenzcorrole. The latter was only formed at low ratios (< 1:8) of 4-sulfophthalic acid to urea. Both complexes are aggregated in aqueous media, but can be partly or fully disaggregated by the addition of Triton X-100. The SnTSTBC complex has lower triplet life times and yields, while binding constant and quenching (of bovine serum albumin) constant are lower for SnTSTBC, compared to SnTSPc. Finally Non-peripherally (α) tetra- (40) and octa-(38a) substituted dodecyl-mercapto tin(IV) phthalocyanines where synthesized and the electrochemical behavior studied. Cyclic voltammetry and spectroelectrochemistry show ring-based reductions for (38a) and (40); the former shows two ring oxidations, while the latter shows only one ring based oxidation. The adsorption kinetics of (38a) and (40) on a gold electrode have been investigated by electrochemical impedance spectroscopy (EIS). The equilibrium constant (K) for the adsorption and the Gibbs free energy ΔG(ads) of the self-assembled monolayer (SAMs) were evaluated based on the Frumkin isotherm. The interaction factor between adsorbate –adsorbate molecules is also discussed.
- Full Text:
- Date Issued: 2008
- Authors: Khene, Mielie Samson
- Date: 2008
- Subjects: Electrochemistry , Photochemistry , Phthalocyanines , Macrocyclic compounds , Spectrum analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4376 , http://hdl.handle.net/10962/d1005041 , Electrochemistry , Photochemistry , Phthalocyanines , Macrocyclic compounds , Spectrum analysis
- Description: Three non-peripherally substituted tin(IV) macrocylic compounds, octahexylphthalocyaninato dichlorotin(IV) (35a), octahexyltetrabenzo-5,10,15-triazaporphyrinato dichlorotin(IV) (35b) and octadecylphthalocyaninato dichlorotin(IV) (35c) were synthesized and their photophysical and electrochemical behaviour studied. Complex (35b), containing a CH group in place of one of the aza nitrogen atom of the phthalocyanine core, shows a split Q band due to its lower symmetry. The triplet state quantum yields were found to be lower than would be expected on the basis of the heavy atom effect of tin as the central metal for phthalocyanine derivatives (35a and 35c). In contrast, (35b) shows a triplet quantum yield ΦT = 0.78. The triplet state lifetimes were solvent dependent, and were higher in THF than in toluene. Cyclic voltammetry and spectroelectrochemistry of the complexes revealed only ring based redox processes. This thesis also reports on the microwave syntheses of tetrasulphonated tin phthalocyanine and tetrasulphonated tin α,β,γ-tetrabenzcorrole. The latter was only formed at low ratios (< 1:8) of 4-sulfophthalic acid to urea. Both complexes are aggregated in aqueous media, but can be partly or fully disaggregated by the addition of Triton X-100. The SnTSTBC complex has lower triplet life times and yields, while binding constant and quenching (of bovine serum albumin) constant are lower for SnTSTBC, compared to SnTSPc. Finally Non-peripherally (α) tetra- (40) and octa-(38a) substituted dodecyl-mercapto tin(IV) phthalocyanines where synthesized and the electrochemical behavior studied. Cyclic voltammetry and spectroelectrochemistry show ring-based reductions for (38a) and (40); the former shows two ring oxidations, while the latter shows only one ring based oxidation. The adsorption kinetics of (38a) and (40) on a gold electrode have been investigated by electrochemical impedance spectroscopy (EIS). The equilibrium constant (K) for the adsorption and the Gibbs free energy ΔG(ads) of the self-assembled monolayer (SAMs) were evaluated based on the Frumkin isotherm. The interaction factor between adsorbate –adsorbate molecules is also discussed.
- Full Text:
- Date Issued: 2008
Synthetic, spectrometric and computer modelling studies of novel ATP analogues
- Gxoyiya, Babalwa Siliziwe Blossom
- Authors: Gxoyiya, Babalwa Siliziwe Blossom
- Date: 2008
- Subjects: Spectrum analysis Tuberculosis -- Treatment Chemotherapy Adenosine triphosphate Adenosine triphosphate -- Synthesis Adenosine triphosphate -- Computer simulation Adenosine triphosphate -- Spectrometric imaging Glutamine synthetase Tuberculosis -- Chemotherapy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4386 , http://hdl.handle.net/10962/d1005051
- Description: This study has been concerned with the design and synthesis of A TP analogues with the potential to act as inhibitors of glutamine synthetase - a novel target for therapeutic intervention in the treatment of tuberculosis. Using a structural -analogy approach, various 3-indolylalkanoic acid, benzimidazole and pyrazolo[3,4-dJpyrimidine derivatives have been prepared and characterized. Alkylation of the heterocyclic bases using 4-(bromomethyl)-2,2-dimethyl-1 ,3-d ioxolane, 2-(bromomethoxy)ethyl acetate and 2-(chloroethoxy)ethanol in the presence of either NaH or BulOK afforded the corresponding N-alkylated derivatives of benzimidazole and 4-aminopyrazolo[3,4-dJpyrimidine (4-APP). Similar reactions with 3-indo lylalkanoic esters resulted in O-alkyl cleavage with the formation of new esters. Alkylation of benzimidazole with allyl bromide, 4-bromobutene and 2-methylbut-2-ene has also been shown to afford the corresponding l-alkenylbenzimidazoles in moderate to excellent yield (43-96%). Subsequent oxidation of these products using CTAP, gave the dihydroxy derivatives in poor to good yields (26-77%). Phosphorylation of various hydroxy derivatives of benzimidazole and 4-APP has been achieved using diethyl chlorophosphate to afford the corresponding monophosphate and 1,2-diphosphate esters. Glycosylation of each of the heterocyclic bases has been successfully achieved using 1,2,3,4,6-penta-O-acetyl-D-glucopyranose and SnCl4 in acetonitri le, while methanolysis of the resulting tetraacetates, using methanolic NaOMe, afforded the hydroxy derivatives in good yield (50-70%). Various 1- and 2-dimensional NMR spectroscopic methods (e.g., IH, 13C, lip, COSY, HSQC and HMBC) have been used to confirm the structures of the synthesized A IP analogues. The application of NMR prediction programmes has been explored, permitting assessment of their agreement with the experimental data and confirmation of assigned structures. High-resolution electron impact (EI) mass spectrometric data have been used to explore the mass fragmentation pathways exhibited by selected derivatives, and certain common fragmentations have been identified. Molecular modelling of selected products as potential glutamine synthetase ligands has been performed on the Accelrys Cerius2 platform, and interactive receptor-ligand docking studies have been conducted using the Ligand-Fit module. These studies have revealed possible hydrogen-boding interactions between the selected analogues and various amino acid residues in the glutamine synthetase active site.
- Full Text:
- Date Issued: 2008
- Authors: Gxoyiya, Babalwa Siliziwe Blossom
- Date: 2008
- Subjects: Spectrum analysis Tuberculosis -- Treatment Chemotherapy Adenosine triphosphate Adenosine triphosphate -- Synthesis Adenosine triphosphate -- Computer simulation Adenosine triphosphate -- Spectrometric imaging Glutamine synthetase Tuberculosis -- Chemotherapy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4386 , http://hdl.handle.net/10962/d1005051
- Description: This study has been concerned with the design and synthesis of A TP analogues with the potential to act as inhibitors of glutamine synthetase - a novel target for therapeutic intervention in the treatment of tuberculosis. Using a structural -analogy approach, various 3-indolylalkanoic acid, benzimidazole and pyrazolo[3,4-dJpyrimidine derivatives have been prepared and characterized. Alkylation of the heterocyclic bases using 4-(bromomethyl)-2,2-dimethyl-1 ,3-d ioxolane, 2-(bromomethoxy)ethyl acetate and 2-(chloroethoxy)ethanol in the presence of either NaH or BulOK afforded the corresponding N-alkylated derivatives of benzimidazole and 4-aminopyrazolo[3,4-dJpyrimidine (4-APP). Similar reactions with 3-indo lylalkanoic esters resulted in O-alkyl cleavage with the formation of new esters. Alkylation of benzimidazole with allyl bromide, 4-bromobutene and 2-methylbut-2-ene has also been shown to afford the corresponding l-alkenylbenzimidazoles in moderate to excellent yield (43-96%). Subsequent oxidation of these products using CTAP, gave the dihydroxy derivatives in poor to good yields (26-77%). Phosphorylation of various hydroxy derivatives of benzimidazole and 4-APP has been achieved using diethyl chlorophosphate to afford the corresponding monophosphate and 1,2-diphosphate esters. Glycosylation of each of the heterocyclic bases has been successfully achieved using 1,2,3,4,6-penta-O-acetyl-D-glucopyranose and SnCl4 in acetonitri le, while methanolysis of the resulting tetraacetates, using methanolic NaOMe, afforded the hydroxy derivatives in good yield (50-70%). Various 1- and 2-dimensional NMR spectroscopic methods (e.g., IH, 13C, lip, COSY, HSQC and HMBC) have been used to confirm the structures of the synthesized A IP analogues. The application of NMR prediction programmes has been explored, permitting assessment of their agreement with the experimental data and confirmation of assigned structures. High-resolution electron impact (EI) mass spectrometric data have been used to explore the mass fragmentation pathways exhibited by selected derivatives, and certain common fragmentations have been identified. Molecular modelling of selected products as potential glutamine synthetase ligands has been performed on the Accelrys Cerius2 platform, and interactive receptor-ligand docking studies have been conducted using the Ligand-Fit module. These studies have revealed possible hydrogen-boding interactions between the selected analogues and various amino acid residues in the glutamine synthetase active site.
- Full Text:
- Date Issued: 2008
Teachers' perceptions of participative management in a primary school in Namibia
- Authors: Kambonde, Samuel Angaleni
- Date: 2008
- Subjects: Education, Elementary -- Namibia Teachers -- Namibia School management and organization -- Namibia Educational leadership -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1795 , http://hdl.handle.net/10962/d1003680
- Description: Participative management, a key theme in contemporary management literature, is one of the central aims of the decentralization policy in Namibian education. Current perceptions of participative management on the part of teachers in Namibia are therefore of topical interest. This study set out to explore such perceptions among teachers in a Namibian primary school. The study is an interpretive case study focusing on six individual teachers’ understanding and experience of participative management within their place of work, a primary school in the Oshikoto region of Namibia. Semi-structured interviews, observation and document analysis were used to gather data. The study revealed a strong sense of commitment among the respondents to participative management and its accompanying practices, such as shared decision making and broad stakeholder involvement. Participative management was implemented chiefly through a committee structure for school organisation and government. Respondents also highlighted challenges facing participative management, such as the persistence of autocratic leadership, conflicts of interest in decision making, laziness and unwillingness among staff members, and a lack of understanding among parents concerning their role in the schooling of their children. HIV/AIDS was also seen to pose challenges to the free and frequent participation of stakeholders. The chief recommendation arising from these findings is that school leaders and managers’ understanding of tenets of participative management, such as site-based management and democratic management approaches, requires improvement and development.
- Full Text:
- Date Issued: 2008
- Authors: Kambonde, Samuel Angaleni
- Date: 2008
- Subjects: Education, Elementary -- Namibia Teachers -- Namibia School management and organization -- Namibia Educational leadership -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1795 , http://hdl.handle.net/10962/d1003680
- Description: Participative management, a key theme in contemporary management literature, is one of the central aims of the decentralization policy in Namibian education. Current perceptions of participative management on the part of teachers in Namibia are therefore of topical interest. This study set out to explore such perceptions among teachers in a Namibian primary school. The study is an interpretive case study focusing on six individual teachers’ understanding and experience of participative management within their place of work, a primary school in the Oshikoto region of Namibia. Semi-structured interviews, observation and document analysis were used to gather data. The study revealed a strong sense of commitment among the respondents to participative management and its accompanying practices, such as shared decision making and broad stakeholder involvement. Participative management was implemented chiefly through a committee structure for school organisation and government. Respondents also highlighted challenges facing participative management, such as the persistence of autocratic leadership, conflicts of interest in decision making, laziness and unwillingness among staff members, and a lack of understanding among parents concerning their role in the schooling of their children. HIV/AIDS was also seen to pose challenges to the free and frequent participation of stakeholders. The chief recommendation arising from these findings is that school leaders and managers’ understanding of tenets of participative management, such as site-based management and democratic management approaches, requires improvement and development.
- Full Text:
- Date Issued: 2008
Teaching reading in grade 4 Namibian classrooms : a case study
- Authors: Mutenda, Josephine
- Date: 2008
- Subjects: Literacy -- Study and teaching (Elementary) -- Namibia English language -- Study and teaching (Elementary) -- Namibia Reading (Elementary) -- Namibia Second language acquisition
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1797 , http://hdl.handle.net/10962/d1003682
- Description: Literacy is currently a topic of great concern in Namibia. Learners in this country have difficulty in reading and writing, and are often functionally illiterate. This study focuses on the beliefs, experiences and practices of teachers of reading in English to second language learners in Grade 4. Grade 4 is the transitional grade from mother tongue to English as the medium of instruction. The switch to English makes teaching reading in that language especially challenging. The study is structured according to the case study mode of enquiry, with the target respondents comprising Grade 4 teachers. Classroom observation, interviews and document analysis were used as means of collecting data. The main findings revealed that beliefs and experience had an impact on the way in which reading was taught in this study. It emerged that the teachers’ childhood experiences of literacy and learning to read are perpetuated in their beliefs, their attitudes, their basic conceptualization of reading and their current practices, all of which directly affect the children in their classes. Although the teachers’ professional training also had some influence on their teaching methods, neither of the two teachers interviewed had received much in-service support on how to teach reading, and they depended to a large extent on their recall of how they had learned to read themselves. Both teachers were taught in a traditional, teacher-centered way, involving phonics, rote-learning and drilling. Because they see themselves as competent readers, they believe that these approaches were effective and worth sustaining. Tentative recommendations arising from analysis of the data indicate possible areas for improvement in the teaching of reading, and offer guidelines to help teachers cope with the challenge.
- Full Text:
- Date Issued: 2008
- Authors: Mutenda, Josephine
- Date: 2008
- Subjects: Literacy -- Study and teaching (Elementary) -- Namibia English language -- Study and teaching (Elementary) -- Namibia Reading (Elementary) -- Namibia Second language acquisition
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1797 , http://hdl.handle.net/10962/d1003682
- Description: Literacy is currently a topic of great concern in Namibia. Learners in this country have difficulty in reading and writing, and are often functionally illiterate. This study focuses on the beliefs, experiences and practices of teachers of reading in English to second language learners in Grade 4. Grade 4 is the transitional grade from mother tongue to English as the medium of instruction. The switch to English makes teaching reading in that language especially challenging. The study is structured according to the case study mode of enquiry, with the target respondents comprising Grade 4 teachers. Classroom observation, interviews and document analysis were used as means of collecting data. The main findings revealed that beliefs and experience had an impact on the way in which reading was taught in this study. It emerged that the teachers’ childhood experiences of literacy and learning to read are perpetuated in their beliefs, their attitudes, their basic conceptualization of reading and their current practices, all of which directly affect the children in their classes. Although the teachers’ professional training also had some influence on their teaching methods, neither of the two teachers interviewed had received much in-service support on how to teach reading, and they depended to a large extent on their recall of how they had learned to read themselves. Both teachers were taught in a traditional, teacher-centered way, involving phonics, rote-learning and drilling. Because they see themselves as competent readers, they believe that these approaches were effective and worth sustaining. Tentative recommendations arising from analysis of the data indicate possible areas for improvement in the teaching of reading, and offer guidelines to help teachers cope with the challenge.
- Full Text:
- Date Issued: 2008
Temperature dependence of the HartRAO pointing model
- Authors: Copley, Charles Judd
- Date: 2008
- Subjects: Astronomical instruments , Observatories -- South Africa , Telescopes , Astronomical observatories , Astronomy -- Data processing , Antennas (Electronics)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5491 , http://hdl.handle.net/10962/d1005277 , Astronomical instruments , Observatories -- South Africa , Telescopes , Astronomical observatories , Astronomy -- Data processing , Antennas (Electronics)
- Description: This thesis investigates control aspects of the Hartebeeshoek Radio Astronomy Observatory (HartRAO) antenna. The installation of a new 22 GHz receiver has required the pointing accuracy to be improved to less than 4 mdeg. The effect of thermal conditions on the the HartRAO antenna pointing offset is investigated using a variety of modelling techniques including simple geometric modelling, neural networks and Principal Component Analysis (PCA). Convincing results were obtained for the Declination pointing offset, where applying certain model predictions to observations resulted in an improvement in Declination pointing offset from 5.5 mdeg to 3.2 mdeg (≈50%). The Right Ascension pointing model was considerably less convincing with an improvement of approximately from 5.5 mdeg to 4.5 mdeg (≈20%) in the Right Ascension pointing offset. The Declination pointing offset can be modelled sufficiently well to reduce the pointing offset to less than 4 mdeg, however further investigation of the underlying causes is required for the Right Ascension pointing offset.
- Full Text:
- Date Issued: 2008
- Authors: Copley, Charles Judd
- Date: 2008
- Subjects: Astronomical instruments , Observatories -- South Africa , Telescopes , Astronomical observatories , Astronomy -- Data processing , Antennas (Electronics)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5491 , http://hdl.handle.net/10962/d1005277 , Astronomical instruments , Observatories -- South Africa , Telescopes , Astronomical observatories , Astronomy -- Data processing , Antennas (Electronics)
- Description: This thesis investigates control aspects of the Hartebeeshoek Radio Astronomy Observatory (HartRAO) antenna. The installation of a new 22 GHz receiver has required the pointing accuracy to be improved to less than 4 mdeg. The effect of thermal conditions on the the HartRAO antenna pointing offset is investigated using a variety of modelling techniques including simple geometric modelling, neural networks and Principal Component Analysis (PCA). Convincing results were obtained for the Declination pointing offset, where applying certain model predictions to observations resulted in an improvement in Declination pointing offset from 5.5 mdeg to 3.2 mdeg (≈50%). The Right Ascension pointing model was considerably less convincing with an improvement of approximately from 5.5 mdeg to 4.5 mdeg (≈20%) in the Right Ascension pointing offset. The Declination pointing offset can be modelled sufficiently well to reduce the pointing offset to less than 4 mdeg, however further investigation of the underlying causes is required for the Right Ascension pointing offset.
- Full Text:
- Date Issued: 2008
That-has-been a discussion on the body cast as that which fixes a subject in time, in relation to notions surrounding the photograph
- Authors: Maree, Christine Fae
- Date: 2008
- Subjects: Barthes, Roland. Camera Lucida Photography, Artistic Photography -- Philosophy Photographic criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2412 , http://hdl.handle.net/10962/d1002208
- Description: Much like a photograph, a casts creates a replica of its referent, thereby immobilising the subject in time. While the subject continues in time and hence ages and inevitably dies the replica does not. With this basic notion of fixing a subject, I have built an argument to contextualise my sculptures, which are made using casts of elderly people. In this discussion I have looked at my works through the ideas of different theorists. The main theorist I have cited is Roland Barthes, specifically with regards to his notion of the photograph as discussed in his book Camera Lucida. I have also referenced three particular artists: Rachel Whiteread, Diane Arbus and Churchill Madikida, as I have found each of their works relate to my work in various ways, creating a different reading from each viewpoint.
- Full Text:
- Date Issued: 2008
- Authors: Maree, Christine Fae
- Date: 2008
- Subjects: Barthes, Roland. Camera Lucida Photography, Artistic Photography -- Philosophy Photographic criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2412 , http://hdl.handle.net/10962/d1002208
- Description: Much like a photograph, a casts creates a replica of its referent, thereby immobilising the subject in time. While the subject continues in time and hence ages and inevitably dies the replica does not. With this basic notion of fixing a subject, I have built an argument to contextualise my sculptures, which are made using casts of elderly people. In this discussion I have looked at my works through the ideas of different theorists. The main theorist I have cited is Roland Barthes, specifically with regards to his notion of the photograph as discussed in his book Camera Lucida. I have also referenced three particular artists: Rachel Whiteread, Diane Arbus and Churchill Madikida, as I have found each of their works relate to my work in various ways, creating a different reading from each viewpoint.
- Full Text:
- Date Issued: 2008
The "other" Africans : re-examining representations of sexuality in the work of Nicholas Hlobo and Zanele Muholi
- Authors: Makhubu, Nomusa
- Date: 2008
- Subjects: Hlobo, Nicholas Muholi, Zanele Women in art Photography, Artistic Homosexuality in art Sex in art Performance art Art, African
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2410 , http://hdl.handle.net/10962/d1002206
- Description: Nicholas Hlobo, a sculptor and performance artist, and Zanele Muholi, a photographer and activist, explore different ways of representing sexuality, particularly homosexuality. It is extremely difficult to discuss African sexuality in light of the stain of colonial attitudes that have exoticised and ascribed hypersexuality to African bodies. Moreover, sexuality is often not discussed in the construction of so-called African traditions and this has contributed to rendering African-ness as an exclusive identity. Tensions within and between categories of African-ness are compounded by constituted regulations. For example, Hlobo investigates the obligation of circumcision which seems to contrast the lifestyle and contexts in which he works and resides, and Muholi represents the existence of homosexual and transgender relations, even within conservative categories. The visual imagery of these two artists investigates the boundaries set by different social constructs. These set boundaries have also affected crimes against bisexual, transgender and homosexual individuals, which are reaching an alarming rate. Hlobo questions the validity of structures that marginalise homosexual individuals through drawing attention to the ambivalence of certain statutes. Muholi seeks to publicise the injustices imposed upon homosexual individuals in order to demonstrate the weight of that crisis. Although the South African legal system condones liberated expressions of sexual identity, due to social prejudices homosexual individuals are still treated as if they are not entitled to basic human rights. As a result, hate-crimes are not reported, and when they are they are not taken seriously. Hlobo and Muholi not only bring these issues to light, but also point out the dilemma inscribed in the social and political history of (South) Africa with regards to collective and individual identities. This thesis seeks to provide an analysis of the visual language used by Hlobo and Muholi to subvert the notion that homosexuality is “un-African” and to complicate concepts of gender, sexuality and identity.
- Full Text:
- Date Issued: 2008
- Authors: Makhubu, Nomusa
- Date: 2008
- Subjects: Hlobo, Nicholas Muholi, Zanele Women in art Photography, Artistic Homosexuality in art Sex in art Performance art Art, African
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2410 , http://hdl.handle.net/10962/d1002206
- Description: Nicholas Hlobo, a sculptor and performance artist, and Zanele Muholi, a photographer and activist, explore different ways of representing sexuality, particularly homosexuality. It is extremely difficult to discuss African sexuality in light of the stain of colonial attitudes that have exoticised and ascribed hypersexuality to African bodies. Moreover, sexuality is often not discussed in the construction of so-called African traditions and this has contributed to rendering African-ness as an exclusive identity. Tensions within and between categories of African-ness are compounded by constituted regulations. For example, Hlobo investigates the obligation of circumcision which seems to contrast the lifestyle and contexts in which he works and resides, and Muholi represents the existence of homosexual and transgender relations, even within conservative categories. The visual imagery of these two artists investigates the boundaries set by different social constructs. These set boundaries have also affected crimes against bisexual, transgender and homosexual individuals, which are reaching an alarming rate. Hlobo questions the validity of structures that marginalise homosexual individuals through drawing attention to the ambivalence of certain statutes. Muholi seeks to publicise the injustices imposed upon homosexual individuals in order to demonstrate the weight of that crisis. Although the South African legal system condones liberated expressions of sexual identity, due to social prejudices homosexual individuals are still treated as if they are not entitled to basic human rights. As a result, hate-crimes are not reported, and when they are they are not taken seriously. Hlobo and Muholi not only bring these issues to light, but also point out the dilemma inscribed in the social and political history of (South) Africa with regards to collective and individual identities. This thesis seeks to provide an analysis of the visual language used by Hlobo and Muholi to subvert the notion that homosexuality is “un-African” and to complicate concepts of gender, sexuality and identity.
- Full Text:
- Date Issued: 2008
The African Peer Review Mechanism : towards Africa's governance audit
- Authors: Molete, Nathan Teboho
- Date: 2008
- Subjects: African Peer Review Mechanism New Partnership for Africa's Development Peer review -- Africa Auditing -- Africa Africa -- Politics and government -- 1960-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2867 , http://hdl.handle.net/10962/d1007681
- Description: The concept of accountability has grown to become an integral part of a broader political and socio-economic transformation. Closely associated to it is the concept of "auditing" which has established itself as a main driving force of accountability and a core means of delivering it. The extent of the rise and expansion of "auditing" has subsequently come to influence every aspect of modern life and this has led to a situation in which practices have had to adapt to the principles of "auditing" processes. Auditing has become prevalent in both the public and private spheres and this impact has far reaching consequences. The concept of "auditing" is evident in the African Peer Review Mechanism (APRM) and is central to its review process. This thesis focuses on the concept of "auditing" in order to illustrate how the APRM has borrowed and applied insights from other disciplinary practices so as to enhance an understanding of accountability and transparency as features of "good governance" and to explicate how these concepts are conceived within the framework of the New Partnership for Africa's Development (NEPAD). It also clarifies the relationship that exists between "peer review" and "auditing" and argues that rather than being considered as two poles marked by distance from each other "auditing" and "peer review" are closely related and mutually constitutive.
- Full Text:
- Date Issued: 2008
- Authors: Molete, Nathan Teboho
- Date: 2008
- Subjects: African Peer Review Mechanism New Partnership for Africa's Development Peer review -- Africa Auditing -- Africa Africa -- Politics and government -- 1960-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2867 , http://hdl.handle.net/10962/d1007681
- Description: The concept of accountability has grown to become an integral part of a broader political and socio-economic transformation. Closely associated to it is the concept of "auditing" which has established itself as a main driving force of accountability and a core means of delivering it. The extent of the rise and expansion of "auditing" has subsequently come to influence every aspect of modern life and this has led to a situation in which practices have had to adapt to the principles of "auditing" processes. Auditing has become prevalent in both the public and private spheres and this impact has far reaching consequences. The concept of "auditing" is evident in the African Peer Review Mechanism (APRM) and is central to its review process. This thesis focuses on the concept of "auditing" in order to illustrate how the APRM has borrowed and applied insights from other disciplinary practices so as to enhance an understanding of accountability and transparency as features of "good governance" and to explicate how these concepts are conceived within the framework of the New Partnership for Africa's Development (NEPAD). It also clarifies the relationship that exists between "peer review" and "auditing" and argues that rather than being considered as two poles marked by distance from each other "auditing" and "peer review" are closely related and mutually constitutive.
- Full Text:
- Date Issued: 2008
The antecedents of customer satisfaction in a financial institution : a qualitative study
- Authors: Bleske, Adrian
- Date: 2008
- Subjects: Standard Bank Properties , Banks and banking -- South Africa , Banks and banking -- Customer services -- South Africa , Financial services industry -- South Africa , Bank management -- South Africa , Banks and banking -- Customer services -- Effect of marketing on
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:840 , http://hdl.handle.net/10962/d1015482
- Description: The following is a case study report on the Cape Town business unit of Standard Bank Properties. The research project falls within the ambit of services marketing which introduces several unique management challenges for service businesses that sell services as a core offering. The principal aim of the case study is to gain an understanding of why customers bank at the business unit and to discover what aspects are critical to customer satisfaction. A further goal of the research is to examine how the business unit could improve customer satisfaction and to highlight any impediments to further improving customer satisfaction at the business unit. It is generally regarded that quality customer service is essential to building customer relationships and hence the research project emphasis on services marketing and customer satisfaction within a financial services context. The paper commences with an overview of the South African Banking Sector and its unique challenges such as the Financial Service Charter and newly introduced legislation such as Financial Intelligence Centre Act. The case study will specifically investigate the property finance industry and a detailed analysis of the business unit's operations and process flow will also be undertaken. The reason for this background information is to assist the reader to understand how the business unit operates. The research project will investigate four unique differences between goods marketing and services marketing whereafter three theoretical propositions are introduced, namely the dyadic interaction and service encounter, the Service Profit Chain and finally Relationship Marketing. Evidence in the form of a narrative will be led from insights obtained from interviews conducted with customers and staff at the business unit against these propositions with support (or otherwise) from independent surveys and documents from the business unit. The result of this analysis is the identification of several areas of concern specifically: New employees and the service encounter, Problems with FICA, Lack of a customer complaint handling system, Empowerment issues, Turnaround times, Reliance on key staff These insights together with the evidence from the literature review will be analysed and several recommendations made to improve customer service and ultimately customer satisfaction at the business unit. Several recommendations for further research are offered as well as the identification of limitations including but not limited to the specificity of the case study report.
- Full Text:
- Date Issued: 2008
- Authors: Bleske, Adrian
- Date: 2008
- Subjects: Standard Bank Properties , Banks and banking -- South Africa , Banks and banking -- Customer services -- South Africa , Financial services industry -- South Africa , Bank management -- South Africa , Banks and banking -- Customer services -- Effect of marketing on
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:840 , http://hdl.handle.net/10962/d1015482
- Description: The following is a case study report on the Cape Town business unit of Standard Bank Properties. The research project falls within the ambit of services marketing which introduces several unique management challenges for service businesses that sell services as a core offering. The principal aim of the case study is to gain an understanding of why customers bank at the business unit and to discover what aspects are critical to customer satisfaction. A further goal of the research is to examine how the business unit could improve customer satisfaction and to highlight any impediments to further improving customer satisfaction at the business unit. It is generally regarded that quality customer service is essential to building customer relationships and hence the research project emphasis on services marketing and customer satisfaction within a financial services context. The paper commences with an overview of the South African Banking Sector and its unique challenges such as the Financial Service Charter and newly introduced legislation such as Financial Intelligence Centre Act. The case study will specifically investigate the property finance industry and a detailed analysis of the business unit's operations and process flow will also be undertaken. The reason for this background information is to assist the reader to understand how the business unit operates. The research project will investigate four unique differences between goods marketing and services marketing whereafter three theoretical propositions are introduced, namely the dyadic interaction and service encounter, the Service Profit Chain and finally Relationship Marketing. Evidence in the form of a narrative will be led from insights obtained from interviews conducted with customers and staff at the business unit against these propositions with support (or otherwise) from independent surveys and documents from the business unit. The result of this analysis is the identification of several areas of concern specifically: New employees and the service encounter, Problems with FICA, Lack of a customer complaint handling system, Empowerment issues, Turnaround times, Reliance on key staff These insights together with the evidence from the literature review will be analysed and several recommendations made to improve customer service and ultimately customer satisfaction at the business unit. Several recommendations for further research are offered as well as the identification of limitations including but not limited to the specificity of the case study report.
- Full Text:
- Date Issued: 2008
The attitudes of isiXhosa-speaking students toward various languages of learning and teaching (LOLT) issues at Rhodes University
- Authors: Aziakpono, Philomina
- Date: 2008
- Subjects: Rhodes University -- Students -- Attitudes Language and education -- South Africa Xhosa language -- Study and teaching (Higher) -- South Africa English language -- Study and teaching (Higher) -- South Africa Education, Bilingual -- South Africa Language policy -- South Africa Language planning -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2339 , http://hdl.handle.net/10962/d1002621
- Description: This study aims at eliciting opinions and beliefs of isiXhosa-speaking students to revealtheir attitudes toward various languages of learning and teaching (LOLT) issues at RhodesUniversity, and to determine the influence of a number of variables (such as age, gender,schooling background, level of study and field of study) on these attitudes. Another aim of the study is to compare the findings of this research to the recent findings on isiXhosaspeaking students’ language attitudes at the University of the Western Cape (Dyers 1999) and the University of Fort Hare (Dalvit 2004). Qualitative and quantitative methods were used: data was gathered using a survey that employed a questionnaire and interviews (individual and focus group). The questionnaire data is analysed through using percentage scores as well as mean values coupled with Chi-square tests, while the interviews are analysed qualitatively to further confirm the results of the quantitative analysis. Results are also compared with other recent surveys at South African universities. The results reveal that respondents had a generally positive attitude toward English as LOLT, based mainly on instrumental motivations. More importantly, there was a positive attitude toward the use of isiXhosa alongside English. The motivations for the use of isiXhosa were both instrumental and integrative in nature. The majority of respondents who supported a bilingual arrangement did not, however, believe that a fully-fledged bilingual policy would be practical, mainly because of the multilingual nature of Rhodes University. They felt, however, that providing English and isiXhosa exam question-papers, bilingual tutor support and isiXhosa definitions of discipline-specific technical terms would facilitate learning. Most of the variables mentioned above had an influence on the relevant language attitudes, often confirming the findings of other studies. For instance, schooling background greatly influenced the language attitudes of respondents. Those from previously advantaged English-only schools showed very positive attitudes toward an English-only policy, while most respondents from formerly disadvantaged DET bilingual schools were favourably disposed toward a bilingual policy of English and isiXhosa at Rhodes University. A comparison of the findings of this study with those of recent findings on isiXhosa students’ language attitudes at other universities reveals that respondents at the University of Fort Hare were most favourable toward a bilingual policy, those at the University of the Western Cape were to some extent favourable toward a bilingual arrangement, while respondents at Rhodes University were least favourable toward a bilingual policy.
- Full Text:
- Date Issued: 2008
- Authors: Aziakpono, Philomina
- Date: 2008
- Subjects: Rhodes University -- Students -- Attitudes Language and education -- South Africa Xhosa language -- Study and teaching (Higher) -- South Africa English language -- Study and teaching (Higher) -- South Africa Education, Bilingual -- South Africa Language policy -- South Africa Language planning -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2339 , http://hdl.handle.net/10962/d1002621
- Description: This study aims at eliciting opinions and beliefs of isiXhosa-speaking students to revealtheir attitudes toward various languages of learning and teaching (LOLT) issues at RhodesUniversity, and to determine the influence of a number of variables (such as age, gender,schooling background, level of study and field of study) on these attitudes. Another aim of the study is to compare the findings of this research to the recent findings on isiXhosaspeaking students’ language attitudes at the University of the Western Cape (Dyers 1999) and the University of Fort Hare (Dalvit 2004). Qualitative and quantitative methods were used: data was gathered using a survey that employed a questionnaire and interviews (individual and focus group). The questionnaire data is analysed through using percentage scores as well as mean values coupled with Chi-square tests, while the interviews are analysed qualitatively to further confirm the results of the quantitative analysis. Results are also compared with other recent surveys at South African universities. The results reveal that respondents had a generally positive attitude toward English as LOLT, based mainly on instrumental motivations. More importantly, there was a positive attitude toward the use of isiXhosa alongside English. The motivations for the use of isiXhosa were both instrumental and integrative in nature. The majority of respondents who supported a bilingual arrangement did not, however, believe that a fully-fledged bilingual policy would be practical, mainly because of the multilingual nature of Rhodes University. They felt, however, that providing English and isiXhosa exam question-papers, bilingual tutor support and isiXhosa definitions of discipline-specific technical terms would facilitate learning. Most of the variables mentioned above had an influence on the relevant language attitudes, often confirming the findings of other studies. For instance, schooling background greatly influenced the language attitudes of respondents. Those from previously advantaged English-only schools showed very positive attitudes toward an English-only policy, while most respondents from formerly disadvantaged DET bilingual schools were favourably disposed toward a bilingual policy of English and isiXhosa at Rhodes University. A comparison of the findings of this study with those of recent findings on isiXhosa students’ language attitudes at other universities reveals that respondents at the University of Fort Hare were most favourable toward a bilingual policy, those at the University of the Western Cape were to some extent favourable toward a bilingual arrangement, while respondents at Rhodes University were least favourable toward a bilingual policy.
- Full Text:
- Date Issued: 2008
The cryopreservation potential and ultrastructure of Agulhas sole Austroglossus pectoralis spermatozoa
- Authors: Markovina, Michael Zeljan
- Date: 2008
- Subjects: Spermatozoa , Spermatozoa -- Cryopreservation , Aquaculture , Fishes -- Breeding , Soleidae , Flatfishes , Agulhas Current (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5251 , http://hdl.handle.net/10962/d1005094 , Spermatozoa , Spermatozoa -- Cryopreservation , Aquaculture , Fishes -- Breeding , Soleidae , Flatfishes , Agulhas Current (South Africa)
- Description: As the estimated market demand for the Agulhas sole Austroglossus pectoralis exceeds the annual catch from trawlers, this species is a potential aquaculture candidate. Broodstock conditioning and gamete preservation is part of research and development aiming at establishing a breeding protocol for a new aquaculture species. Based on a literature review of the morphology of pleuronectiform spermatozoa, this study was designed firstly, to contribute to the field of spermatozoan morphology by describing the ultrastructure of A. pectoralis spermatozoa. This was followed by an experiment to cryopreserve mature spermatozoa to provide baseline data for future studies on this and related species. The testis of A. pectoralis was a paired structure encased in a membrane, the tunica albuginea. The primary testis was located on the dorsal surface of the rib cage and the secondary testis on the ventral side. The testis was of an unrestricted spermatogonial type, based upon observations of spermatogonia along the entire length of the lobule. Mature spermatozoa of A. pectoralis had an acrosome-free ovoid head 1.68 ± 1.6μm in length and 1.7 ± 1.6μm in diameter, a short mid-piece of 0.5 ± 0.1μm in length, containing 7 irregularly shaped mitochondria forming a ring-like structure at the base of the nucleus. The flagellae were 47.4 ± 4.8μm in length, most with two plasma membrane lateral fin-like projections. However, some flagellae had either zero or three lateral fin projections. Cross-sections of the flagellae showed an axenome with a 9+2 microtubule configuration. The proximal and distal centriols were coaxal, situated deep within the nuclear fossa. The structure of A. pectoralis spermatozoa conformed to the type 1 ect-aquasperm, also found in externally fertilizing species. This type has been suggested to be the plesiomorphic form in Neopterigians. Finally, this study contributed to a cryopreservation protocol for A. pectoralis spermatozoa by testing the two cryoprotectants dimethyl sulphoxide (DMSO) and glycerol. Glycerol, at a concentration of 10%, offered better cryoprotection than DMSO. This was established using flow cytometry analysis of post-thaw nuclear membrane integrity after 64 days of storage in liquid nitrogen. The toxicity of DMSO to isolated cellular proteins may have resulted in DMSO-treated sperm having the highest percent (35.2% ± 3.2%) of non-viable cells compared with 23.0% ± 2.5% and 27.8% ± 3.4% for glycerol and the control, respectively. The presence of sucrose in the Modified Mounib Medium extender solution may explain why 45.5% ± 5% of the sperm cells were potentially viable in the control treatment. Initially, the white margined sole Dagatichthys marginatus (Soleidae) was selected as the most suitable candidate for flatfish aquaculture in South Africa. Thus, the aim of this study was to investigate the cryogenic potential and ultrastructure of D. marginatus spermatozoa. However, due to a skewed sex ratio, there were not enough males available to study this species. A skewed sex ratio is common amongst soleids, thus, the need to develop effective cryopreservation methods and to develop an understanding of sperm morphology so that the best time for cryopreservation can be chosen. In conclusion, this first description of spermatozan morphology of A. pectoralis contributed to our understanding of soleid sperm ultrastructure. In addition, a comparison of testis appearance between fish sampled just prior to spawning season and fish with mature sperm provided information on the spawning season of this species. The findings from the cryopreservation experiment suggested that glycerol was a feasible cryoprotectant for this species when sperm was prepared under field conditions.
- Full Text:
- Date Issued: 2008
- Authors: Markovina, Michael Zeljan
- Date: 2008
- Subjects: Spermatozoa , Spermatozoa -- Cryopreservation , Aquaculture , Fishes -- Breeding , Soleidae , Flatfishes , Agulhas Current (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5251 , http://hdl.handle.net/10962/d1005094 , Spermatozoa , Spermatozoa -- Cryopreservation , Aquaculture , Fishes -- Breeding , Soleidae , Flatfishes , Agulhas Current (South Africa)
- Description: As the estimated market demand for the Agulhas sole Austroglossus pectoralis exceeds the annual catch from trawlers, this species is a potential aquaculture candidate. Broodstock conditioning and gamete preservation is part of research and development aiming at establishing a breeding protocol for a new aquaculture species. Based on a literature review of the morphology of pleuronectiform spermatozoa, this study was designed firstly, to contribute to the field of spermatozoan morphology by describing the ultrastructure of A. pectoralis spermatozoa. This was followed by an experiment to cryopreserve mature spermatozoa to provide baseline data for future studies on this and related species. The testis of A. pectoralis was a paired structure encased in a membrane, the tunica albuginea. The primary testis was located on the dorsal surface of the rib cage and the secondary testis on the ventral side. The testis was of an unrestricted spermatogonial type, based upon observations of spermatogonia along the entire length of the lobule. Mature spermatozoa of A. pectoralis had an acrosome-free ovoid head 1.68 ± 1.6μm in length and 1.7 ± 1.6μm in diameter, a short mid-piece of 0.5 ± 0.1μm in length, containing 7 irregularly shaped mitochondria forming a ring-like structure at the base of the nucleus. The flagellae were 47.4 ± 4.8μm in length, most with two plasma membrane lateral fin-like projections. However, some flagellae had either zero or three lateral fin projections. Cross-sections of the flagellae showed an axenome with a 9+2 microtubule configuration. The proximal and distal centriols were coaxal, situated deep within the nuclear fossa. The structure of A. pectoralis spermatozoa conformed to the type 1 ect-aquasperm, also found in externally fertilizing species. This type has been suggested to be the plesiomorphic form in Neopterigians. Finally, this study contributed to a cryopreservation protocol for A. pectoralis spermatozoa by testing the two cryoprotectants dimethyl sulphoxide (DMSO) and glycerol. Glycerol, at a concentration of 10%, offered better cryoprotection than DMSO. This was established using flow cytometry analysis of post-thaw nuclear membrane integrity after 64 days of storage in liquid nitrogen. The toxicity of DMSO to isolated cellular proteins may have resulted in DMSO-treated sperm having the highest percent (35.2% ± 3.2%) of non-viable cells compared with 23.0% ± 2.5% and 27.8% ± 3.4% for glycerol and the control, respectively. The presence of sucrose in the Modified Mounib Medium extender solution may explain why 45.5% ± 5% of the sperm cells were potentially viable in the control treatment. Initially, the white margined sole Dagatichthys marginatus (Soleidae) was selected as the most suitable candidate for flatfish aquaculture in South Africa. Thus, the aim of this study was to investigate the cryogenic potential and ultrastructure of D. marginatus spermatozoa. However, due to a skewed sex ratio, there were not enough males available to study this species. A skewed sex ratio is common amongst soleids, thus, the need to develop effective cryopreservation methods and to develop an understanding of sperm morphology so that the best time for cryopreservation can be chosen. In conclusion, this first description of spermatozan morphology of A. pectoralis contributed to our understanding of soleid sperm ultrastructure. In addition, a comparison of testis appearance between fish sampled just prior to spawning season and fish with mature sperm provided information on the spawning season of this species. The findings from the cryopreservation experiment suggested that glycerol was a feasible cryoprotectant for this species when sperm was prepared under field conditions.
- Full Text:
- Date Issued: 2008
The development and evaluation of a cohesion-building programme for a South African male collegiate basketball team
- Authors: Razafimbola, Sandimampita
- Date: 2008
- Subjects: Teamwork (Sports) Basketball teams College sports Sports -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3040 , http://hdl.handle.net/10962/d1002549
- Description: There is a general consensus among sport coaches and practitioners that it is better to work with a cohesive team. Research on cohesion has provided positive links between cohesion and performance as well as the overall well-being of the team and its members. The purpose of this study is to develop and evaluate a cohesion-building programme under an Action Research paradigm. The Group Environment Questionnaire, in parallel with focus group discussions were used to assist in the development and evaluation of a cohesion-building programme tailored to the specific needs of the Rhodes University men’s basketball 1st team. The team is known to be a good team but it was missing something that made it become great. Fostering higher cohesiveness was deemed to be the missing link to the chain of success. Various changes were brought to the 1) team structure, 2) team processes, 3) team environment to enhance the team’s cohesiveness levels. It was found that the programme was positive and powerful in that it accelerated the process of cohesion building within the team. It was also found that the programme had the power to transcend demographical barriers and unite people from diverse backgrounds. Finally, the programme increased the team’s performance level and enabled it to achieve objectives that were never achieved by any other men’s basketball team at Rhodes University before. Naturally there are going to be some ups and downs, especially if you have individuals trying to achieve at a high level. But when we stepped in between the lines, we knew what we were capable of doing. When a pressure situation presented itself, we were plugged into one another like a cohesive unit. That’s why we were able to come back so often and win so many close games. And that’s why we were able to beat more talented team. - Michael Jordan (former Chicago Bulls; NBA Hall of Famer).
- Full Text:
- Date Issued: 2008
- Authors: Razafimbola, Sandimampita
- Date: 2008
- Subjects: Teamwork (Sports) Basketball teams College sports Sports -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3040 , http://hdl.handle.net/10962/d1002549
- Description: There is a general consensus among sport coaches and practitioners that it is better to work with a cohesive team. Research on cohesion has provided positive links between cohesion and performance as well as the overall well-being of the team and its members. The purpose of this study is to develop and evaluate a cohesion-building programme under an Action Research paradigm. The Group Environment Questionnaire, in parallel with focus group discussions were used to assist in the development and evaluation of a cohesion-building programme tailored to the specific needs of the Rhodes University men’s basketball 1st team. The team is known to be a good team but it was missing something that made it become great. Fostering higher cohesiveness was deemed to be the missing link to the chain of success. Various changes were brought to the 1) team structure, 2) team processes, 3) team environment to enhance the team’s cohesiveness levels. It was found that the programme was positive and powerful in that it accelerated the process of cohesion building within the team. It was also found that the programme had the power to transcend demographical barriers and unite people from diverse backgrounds. Finally, the programme increased the team’s performance level and enabled it to achieve objectives that were never achieved by any other men’s basketball team at Rhodes University before. Naturally there are going to be some ups and downs, especially if you have individuals trying to achieve at a high level. But when we stepped in between the lines, we knew what we were capable of doing. When a pressure situation presented itself, we were plugged into one another like a cohesive unit. That’s why we were able to come back so often and win so many close games. And that’s why we were able to beat more talented team. - Michael Jordan (former Chicago Bulls; NBA Hall of Famer).
- Full Text:
- Date Issued: 2008
The development and evaluation of a custom-built synchronous online learning environment for tertiary education in South Africa
- Authors: Halse, Michelle Louise
- Date: 2008 , 2008-02-23
- Subjects: Education, Higher -- South Africa -- Computer-assisted instruction , Universities and colleges -- Computer networks -- South Africa , Internet in higher education -- South Africa , Distance education -- South Africa -- Computer-assisted instruction , Computer-assisted instruction -- South Africa , Computer science -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4636 , http://hdl.handle.net/10962/d1006545 , Education, Higher -- South Africa -- Computer-assisted instruction , Universities and colleges -- Computer networks -- South Africa , Internet in higher education -- South Africa , Distance education -- South Africa -- Computer-assisted instruction , Computer-assisted instruction -- South Africa , Computer science -- Study and teaching (Higher) -- South Africa
- Description: The Departments of Computer Science and Information Systems at Rhodes University currently share certain honours-level (fourth year) course modules with students from the corresponding departments at the previously disadvantaged University of Fort Hare. These lectures are currently delivered using video-conferencing. This was found to present a number of problems including challenges in terms of implementing desired pedagogical approaches, inequitable learning experiences, student disengagement at the remote venue, and inflexibility of the video-conferencing system. In order to address these problems, various e-learning modes were investigated and synchronous e-learning were found to offer a number of advantages over asynchronous e-learning. Live Virtual Classrooms (LVCs) were identified as synchronous e-learning tools that support the pedagogical principles important to the two universities and to the broader context of South African tertiary education, and commercial LVC applications were investigated and evaluated. Informed by the results of this investigation a small, simple LVC was designed, developed and customised for use in a predominantly academic sphere and deployment in a South African tertiary educational context. Testing and evaluation of this solution was carried out and the results analysed in terms of the LVC’s technical merits and the pedagogical value of the solution as experienced by students and lecturers/facilitators. An evaluation of this solution indicated that the LVC solves a number of the identified problems with video-conferencing and also provides a flexible/customisable/extensible solution that supports highly interactive, collaborative, learner-centred education. The custom LVC solution could be easily adapted to the specific needs of any tertiary educational institute in the country, and results may benefit other tertiary educational institutions involved in or dependant on distance learning.
- Full Text:
- Date Issued: 2008
- Authors: Halse, Michelle Louise
- Date: 2008 , 2008-02-23
- Subjects: Education, Higher -- South Africa -- Computer-assisted instruction , Universities and colleges -- Computer networks -- South Africa , Internet in higher education -- South Africa , Distance education -- South Africa -- Computer-assisted instruction , Computer-assisted instruction -- South Africa , Computer science -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4636 , http://hdl.handle.net/10962/d1006545 , Education, Higher -- South Africa -- Computer-assisted instruction , Universities and colleges -- Computer networks -- South Africa , Internet in higher education -- South Africa , Distance education -- South Africa -- Computer-assisted instruction , Computer-assisted instruction -- South Africa , Computer science -- Study and teaching (Higher) -- South Africa
- Description: The Departments of Computer Science and Information Systems at Rhodes University currently share certain honours-level (fourth year) course modules with students from the corresponding departments at the previously disadvantaged University of Fort Hare. These lectures are currently delivered using video-conferencing. This was found to present a number of problems including challenges in terms of implementing desired pedagogical approaches, inequitable learning experiences, student disengagement at the remote venue, and inflexibility of the video-conferencing system. In order to address these problems, various e-learning modes were investigated and synchronous e-learning were found to offer a number of advantages over asynchronous e-learning. Live Virtual Classrooms (LVCs) were identified as synchronous e-learning tools that support the pedagogical principles important to the two universities and to the broader context of South African tertiary education, and commercial LVC applications were investigated and evaluated. Informed by the results of this investigation a small, simple LVC was designed, developed and customised for use in a predominantly academic sphere and deployment in a South African tertiary educational context. Testing and evaluation of this solution was carried out and the results analysed in terms of the LVC’s technical merits and the pedagogical value of the solution as experienced by students and lecturers/facilitators. An evaluation of this solution indicated that the LVC solves a number of the identified problems with video-conferencing and also provides a flexible/customisable/extensible solution that supports highly interactive, collaborative, learner-centred education. The custom LVC solution could be easily adapted to the specific needs of any tertiary educational institute in the country, and results may benefit other tertiary educational institutions involved in or dependant on distance learning.
- Full Text:
- Date Issued: 2008
The development of a putative microbial product for use in crop production
- Authors: Gumede, Halalisani
- Date: 2008
- Subjects: Agricultural productivity , Agriculture -- Economic aspects , Microbial products , Bacterial diseases of plants , Biological pest control agents , Lettuce -- Diseases and pests , Crops -- Nutrition , Bacillus (Bacteria) , Phytopathogenic microorganisms -- Control
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3945 , http://hdl.handle.net/10962/d1004004 , Agricultural productivity , Agriculture -- Economic aspects , Microbial products , Bacterial diseases of plants , Biological pest control agents , Lettuce -- Diseases and pests , Crops -- Nutrition , Bacillus (Bacteria) , Phytopathogenic microorganisms -- Control
- Description: The challenges faced by the agricultural sector especially around improving production yields using environmentally friendly solutions have received market attention. Biological intervention can range from application of biological products to enhance the nutritional value of crops or to control plant pathogens. Biostart, a biological product that demonstrated growth enhancement when applied in lettuce crops is currently in the market. The product is comprised of a consortium of bacterial isolates (Bacillus licheniformis, Brevibacillus laterosporus and Bacillus laterosporus) but the contribution of the individual isolates to growth enhancement had not been elucidated. Green house experiments on lettuce seedlings with individual and mixed treatments were commissioned to determine such contribution. There was either no or marginal growth enhancement observed in the experiments. The results showed that the product was effective as a consortium and not as individual isolates. Further isolation and screening for potential Bacilli with antifungal properties was undertaken. An isolate identified as Bacillus subtilis that demonstrated inhibition against a wide spectrum of fungi, and especially the phytopathogenic Verticillium dahliae and Fusarium oxysporum, was successfully identified. The isolate was cryo-preserved and cultivated to significant levels at bench scale. A characterized comparison of different putative products with known systematic fungicide showed potential application even of heat treated products. The product showed control V. dahliae when tested in green houses with potatoes and tomatoes as test crops. This isolate has been targeted for further development as a biological control product.
- Full Text:
- Date Issued: 2008
- Authors: Gumede, Halalisani
- Date: 2008
- Subjects: Agricultural productivity , Agriculture -- Economic aspects , Microbial products , Bacterial diseases of plants , Biological pest control agents , Lettuce -- Diseases and pests , Crops -- Nutrition , Bacillus (Bacteria) , Phytopathogenic microorganisms -- Control
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3945 , http://hdl.handle.net/10962/d1004004 , Agricultural productivity , Agriculture -- Economic aspects , Microbial products , Bacterial diseases of plants , Biological pest control agents , Lettuce -- Diseases and pests , Crops -- Nutrition , Bacillus (Bacteria) , Phytopathogenic microorganisms -- Control
- Description: The challenges faced by the agricultural sector especially around improving production yields using environmentally friendly solutions have received market attention. Biological intervention can range from application of biological products to enhance the nutritional value of crops or to control plant pathogens. Biostart, a biological product that demonstrated growth enhancement when applied in lettuce crops is currently in the market. The product is comprised of a consortium of bacterial isolates (Bacillus licheniformis, Brevibacillus laterosporus and Bacillus laterosporus) but the contribution of the individual isolates to growth enhancement had not been elucidated. Green house experiments on lettuce seedlings with individual and mixed treatments were commissioned to determine such contribution. There was either no or marginal growth enhancement observed in the experiments. The results showed that the product was effective as a consortium and not as individual isolates. Further isolation and screening for potential Bacilli with antifungal properties was undertaken. An isolate identified as Bacillus subtilis that demonstrated inhibition against a wide spectrum of fungi, and especially the phytopathogenic Verticillium dahliae and Fusarium oxysporum, was successfully identified. The isolate was cryo-preserved and cultivated to significant levels at bench scale. A characterized comparison of different putative products with known systematic fungicide showed potential application even of heat treated products. The product showed control V. dahliae when tested in green houses with potatoes and tomatoes as test crops. This isolate has been targeted for further development as a biological control product.
- Full Text:
- Date Issued: 2008
The devil in disguise a comparative study of Thomas Mann's "Doktor Faustus" (1947) and Klaus Mann's "Mephisto" (1936), focussing on the role of art as an allegory of the rise and fall of Nazi Germany
- Authors: French, Rebecca S C
- Date: 2008
- Subjects: Mann, Thomas, 1875-1955 Doktor Faustus Mann, Klaus, 1906-1949 Mephisto Arts, German -- 20th Century Art, Germany -- 20th Century National socialism in art National socialism in literature
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3582 , http://hdl.handle.net/10962/d1002157
- Description: This thesis compares the novels Doktor Faustus: das Leben des deutschen Tonsetzers Adrian Leverkühn, erzählt von einem Freunde (Thomas Mann) and Mephisto: Roman einer Karriere (Klaus Mann), insofar as they are portrayals of the situation in Germany during the Third Reich. Essentially a comparative study, I explore similarities and differences – thematic and conceptual – by situating both novels in their socio-historical moment (Chapter 1), exploring their conceptions of German national identity (Chapter 2), tracing intertextual connections to other works (Chapter 3), and, finally, examining their understanding of and reliance on art as insofar as it provides the allegorical framework for their respective portrayals of Nazi Germany (Chapter 4).
- Full Text:
- Date Issued: 2008
- Authors: French, Rebecca S C
- Date: 2008
- Subjects: Mann, Thomas, 1875-1955 Doktor Faustus Mann, Klaus, 1906-1949 Mephisto Arts, German -- 20th Century Art, Germany -- 20th Century National socialism in art National socialism in literature
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3582 , http://hdl.handle.net/10962/d1002157
- Description: This thesis compares the novels Doktor Faustus: das Leben des deutschen Tonsetzers Adrian Leverkühn, erzählt von einem Freunde (Thomas Mann) and Mephisto: Roman einer Karriere (Klaus Mann), insofar as they are portrayals of the situation in Germany during the Third Reich. Essentially a comparative study, I explore similarities and differences – thematic and conceptual – by situating both novels in their socio-historical moment (Chapter 1), exploring their conceptions of German national identity (Chapter 2), tracing intertextual connections to other works (Chapter 3), and, finally, examining their understanding of and reliance on art as insofar as it provides the allegorical framework for their respective portrayals of Nazi Germany (Chapter 4).
- Full Text:
- Date Issued: 2008
The difficulty of living well: effort and failure in the good life
- Authors: Moore, Jesse Alexander
- Date: 2008
- Subjects: Conduct of life Ethics Happiness Values Failure (Psychology) Success Struggle
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2715 , http://hdl.handle.net/10962/d1002845
- Description: We all want to live good lives, but due to the difficulty involved, few of us ever succeed. We usually either fail in our attempts to live well or remain with our safer, and less worthwhile, options. In spite of this, there has been little, if any, investigation of the role that difficulty plays in our attempts to live well, and thus in our conceptions of the good life. Within the field of the good life, philosophers tend to acknowledge the fact that good lives are difficult to live, and leave it at that. Since we must all face the difficulty of living well, the lack of analysis of the implications of difficulty seems a glaring oversight. In order to redress this, I explore the role that difficulty plays in two requirements for living well, namely achievement and reflection. Firstly, I examine the relationship between effort and achievement. I argue that difficulty just is the requirement of effort, and that it is required in order for our achievements to be meaningful and for us to value them. Secondly, I look at the relationship between failure and reflection. I argue that reflection on our failures can lead us to knowledge that helps us to live well and that we would not usually come to if we did not fail. Finally, I look at the roles of effort and failure in some accounts of the good life and I draw on psychological research and theory to provide support for my conclusions about the positive effects of effort. I conclude by examining the implications of reducing difficulty for the future of humankind.
- Full Text:
- Date Issued: 2008
- Authors: Moore, Jesse Alexander
- Date: 2008
- Subjects: Conduct of life Ethics Happiness Values Failure (Psychology) Success Struggle
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2715 , http://hdl.handle.net/10962/d1002845
- Description: We all want to live good lives, but due to the difficulty involved, few of us ever succeed. We usually either fail in our attempts to live well or remain with our safer, and less worthwhile, options. In spite of this, there has been little, if any, investigation of the role that difficulty plays in our attempts to live well, and thus in our conceptions of the good life. Within the field of the good life, philosophers tend to acknowledge the fact that good lives are difficult to live, and leave it at that. Since we must all face the difficulty of living well, the lack of analysis of the implications of difficulty seems a glaring oversight. In order to redress this, I explore the role that difficulty plays in two requirements for living well, namely achievement and reflection. Firstly, I examine the relationship between effort and achievement. I argue that difficulty just is the requirement of effort, and that it is required in order for our achievements to be meaningful and for us to value them. Secondly, I look at the relationship between failure and reflection. I argue that reflection on our failures can lead us to knowledge that helps us to live well and that we would not usually come to if we did not fail. Finally, I look at the roles of effort and failure in some accounts of the good life and I draw on psychological research and theory to provide support for my conclusions about the positive effects of effort. I conclude by examining the implications of reducing difficulty for the future of humankind.
- Full Text:
- Date Issued: 2008