Synthesis and photophysical properties of a novel zinc photosensitizer and its gold nanoparticle conjugate
- Moeno, Sharon, Antunes, Edith M, Nyokong, Tebello
- Authors: Moeno, Sharon , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247100 , vital:51546 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.07.007"
- Description: The peripherally tetra substituted zinc phthalocyanine with 1,6-hexanedithiol as substituent (THdTZnPc, 3) was synthesized and is reported for the first time in this work. The potential of this zinc complex as a suitable photosensitizer for use in photodynamic therapy was determined through the investigation of the photophysical and photochemical properties. In this work complex 3 is attached to gold nanoparticles through the terminal thiol groups of the phthalocyanine resulting in a 3-AuNP conjugate whose photophysicochemical properties are investigated. Fluorescence lifetimes were determined using time correlated single photon counting and they show an increase in the abundance of the monomeric species (τ2) for the Pc in the 3-AuNP conjugate: ∼1 and 0.71 (with respective lifetimes 2.69 ns and 2.86 ns) compared to the free complex 3 with abundances of 0.12 and 0.13 (with respective lifetimes 3.36 ns and 3.28 ns) in DMSO and DMF, respectively.
- Full Text:
- Date Issued: 2011
- Authors: Moeno, Sharon , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247100 , vital:51546 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.07.007"
- Description: The peripherally tetra substituted zinc phthalocyanine with 1,6-hexanedithiol as substituent (THdTZnPc, 3) was synthesized and is reported for the first time in this work. The potential of this zinc complex as a suitable photosensitizer for use in photodynamic therapy was determined through the investigation of the photophysical and photochemical properties. In this work complex 3 is attached to gold nanoparticles through the terminal thiol groups of the phthalocyanine resulting in a 3-AuNP conjugate whose photophysicochemical properties are investigated. Fluorescence lifetimes were determined using time correlated single photon counting and they show an increase in the abundance of the monomeric species (τ2) for the Pc in the 3-AuNP conjugate: ∼1 and 0.71 (with respective lifetimes 2.69 ns and 2.86 ns) compared to the free complex 3 with abundances of 0.12 and 0.13 (with respective lifetimes 3.36 ns and 3.28 ns) in DMSO and DMF, respectively.
- Full Text:
- Date Issued: 2011
Synthesis and photophysical studies of CdTe quantum dot-monosubstituted zinc phthalocyanine conjugates
- D'Souza, Sarah, Antunes, Edith M, Nyokong, Tebello
- Authors: D'Souza, Sarah , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247825 , vital:51621 , xlink:href="https://doi.org/10.1016/j.ica.2010.12.027"
- Description: The linkage of unsymmetrically monosubstituted 4-aminophenoxy zinc phthalocyanine (ZnAPPc, 5) to CdTe quantum dots capped with mercaptopropionic acid (MPA), L-cysteine (L-cys) or thioglycolic acid (TGA) has been achieved using the coupling agents ethyl-N(3-dimethylaminopropyl) carbodiimide and N-hydroxy succinimide, which facilitate formation of an amide bond to form the QD–ZnAPPc-linked conjugate. The formation of the amide bond was confirmed using Raman and IR spectroscopies. Atomic force microscopy (AFM) and UV–Vis spectroscopy were used further to characterise the conjugate. Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnAPPc in both the linked (QD–ZnAPPc-linked) and mixed (QD:ZnAPPc-mixed) conjugates. The linked L-cys and TGA QDs conjugates (QD–ZnAPPc-linked) gave the largest FRET efficiencies hence showing the advantages of covalent linking. Fluorescence quantum yields of QDs were decreased in QD:ZnAPPc-mixed and QD:ZnAPPc-linked.
- Full Text:
- Date Issued: 2011
- Authors: D'Souza, Sarah , Antunes, Edith M , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247825 , vital:51621 , xlink:href="https://doi.org/10.1016/j.ica.2010.12.027"
- Description: The linkage of unsymmetrically monosubstituted 4-aminophenoxy zinc phthalocyanine (ZnAPPc, 5) to CdTe quantum dots capped with mercaptopropionic acid (MPA), L-cysteine (L-cys) or thioglycolic acid (TGA) has been achieved using the coupling agents ethyl-N(3-dimethylaminopropyl) carbodiimide and N-hydroxy succinimide, which facilitate formation of an amide bond to form the QD–ZnAPPc-linked conjugate. The formation of the amide bond was confirmed using Raman and IR spectroscopies. Atomic force microscopy (AFM) and UV–Vis spectroscopy were used further to characterise the conjugate. Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnAPPc in both the linked (QD–ZnAPPc-linked) and mixed (QD:ZnAPPc-mixed) conjugates. The linked L-cys and TGA QDs conjugates (QD–ZnAPPc-linked) gave the largest FRET efficiencies hence showing the advantages of covalent linking. Fluorescence quantum yields of QDs were decreased in QD:ZnAPPc-mixed and QD:ZnAPPc-linked.
- Full Text:
- Date Issued: 2011
Synthesis and photophysical studies of monocarboxy phthalocyanines containing quaternizable groups
- Arslanoğlu, Yasin, Nyokong, Tebello
- Authors: Arslanoğlu, Yasin , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246992 , vital:51535 , xlink:href="https://doi.org/10.1016/j.poly.2011.08.009"
- Description: This work reports on the synthesis and photophysical properties of novel unsymmetrically substituted monocarboxy magnesium (MgPc, 3), aluminum (ClAlPc, 4) and unmetallated (H2Pc, 5) phthalocyanines. Magnesium phthalocyanine (3) was converted into water soluble quaternized derivative (QMgPc, 6) by reaction with methyl iodide. The synthesized phthalocyanines were characterized by IR, UV–Vis, NMR, mass spectrometry and elemental analyses. Photophysical and photochemical studies were carried out in order to determine the potential of the complexes as photosensitizers for use in photodynamic therapy. Triplet quantum yields ranged from 0.37 to 0.40 and triplet lifetimes from 110 to 140 μs in DMSO.
- Full Text:
- Date Issued: 2011
- Authors: Arslanoğlu, Yasin , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246992 , vital:51535 , xlink:href="https://doi.org/10.1016/j.poly.2011.08.009"
- Description: This work reports on the synthesis and photophysical properties of novel unsymmetrically substituted monocarboxy magnesium (MgPc, 3), aluminum (ClAlPc, 4) and unmetallated (H2Pc, 5) phthalocyanines. Magnesium phthalocyanine (3) was converted into water soluble quaternized derivative (QMgPc, 6) by reaction with methyl iodide. The synthesized phthalocyanines were characterized by IR, UV–Vis, NMR, mass spectrometry and elemental analyses. Photophysical and photochemical studies were carried out in order to determine the potential of the complexes as photosensitizers for use in photodynamic therapy. Triplet quantum yields ranged from 0.37 to 0.40 and triplet lifetimes from 110 to 140 μs in DMSO.
- Full Text:
- Date Issued: 2011
Synthesis and photophysical studies of phthalocyanine–gold nanoparticle conjugates
- Nombona, Nolwazi, Antunes, Edith M, Litwinski, Christian, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248438 , vital:51686 , xlink:href="https://doi.org/10.1039/C1DT11151E"
- Description: This work reports on the synthesis, characterization and photophysical studies of phthalocyanine–gold nanoparticle conjugates. The phthalocyanine complexes are: tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyanine (3), 2,9,17,23-tetrakis-[(1, 6-hexanedithiol) phthalocyaninato]zinc(II) (8) and [8,15,22-tris-(naptho)-2(amidoethanethiol) phthalocyanato] zinc(II)(10). The gold nanoparticles were characterized using transmission electron microscopy, X-ray diffraction, atomic force microscopy and UV-vis spectroscopy where the size was confirmed to be ∼5 nm. The phthalocyanine Au nanoparticle conjugates showed lower fluorescence quantum yield values with similar fluorescence lifetimes compared to the free phthalocyanines. The Au nanoparticle conjugates of 3 and 10 also showed higher triplet quantum yields of 0.69 to 0.71, respectively. A lower triplet quantum yield was obtained for the conjugate compared to free phthalocyanine for complex 8. The triplet lifetimes ranged from 70 to 92 μs for the conjugates and from 110 to 304 μs for unbound Pc complexes.
- Full Text:
- Date Issued: 2011
- Authors: Nombona, Nolwazi , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248438 , vital:51686 , xlink:href="https://doi.org/10.1039/C1DT11151E"
- Description: This work reports on the synthesis, characterization and photophysical studies of phthalocyanine–gold nanoparticle conjugates. The phthalocyanine complexes are: tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyanine (3), 2,9,17,23-tetrakis-[(1, 6-hexanedithiol) phthalocyaninato]zinc(II) (8) and [8,15,22-tris-(naptho)-2(amidoethanethiol) phthalocyanato] zinc(II)(10). The gold nanoparticles were characterized using transmission electron microscopy, X-ray diffraction, atomic force microscopy and UV-vis spectroscopy where the size was confirmed to be ∼5 nm. The phthalocyanine Au nanoparticle conjugates showed lower fluorescence quantum yield values with similar fluorescence lifetimes compared to the free phthalocyanines. The Au nanoparticle conjugates of 3 and 10 also showed higher triplet quantum yields of 0.69 to 0.71, respectively. A lower triplet quantum yield was obtained for the conjugate compared to free phthalocyanine for complex 8. The triplet lifetimes ranged from 70 to 92 μs for the conjugates and from 110 to 304 μs for unbound Pc complexes.
- Full Text:
- Date Issued: 2011
Synthesis of bromochloromethane using phase transfer catalysis
- Authors: Brooks, Lancelot L
- Date: 2011
- Subjects: Chemistry, Analytic , Fire extinguishing agents , Chemical systems , Physical science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10382 , http://hdl.handle.net/10948/d1008162 , Chemistry, Analytic , Fire extinguishing agents , Chemical systems , Physical science
- Description: The synthesis of bromochloromethane (BCM) in a batch reactor, using phase transfer catalysis, was investigated. During the synthetic procedure, sodium bromide (100.0g, 0.97mol) along with an excess amount of dichloromethane (265.0g, 3.12 mol) was charged to a reactor containing benzyl triethylammonium chloride (13 mmol), dissolved in 50 ml of water. The bench scale reactions were all carried out in a Parr 4520 bench top pressure reactor coupled to a Parr 4841 temperature controller. The method produced a 50.0 percent yield of the product BCM after a reaction time of 12 to 13 hours. The main objective for this investigation was to optimize the abovementioned reaction with respect to yield and reactor throughput. Quantitative analysis of BCM was performed on a Focus Gas Chromatograph, fitted with a flame ionization detector, and a BP20 column (30m × 0,32mm ID × 0,25 mm). Delta software, version 5.0, was applied for data collection and processing. The injector and detector port were set at 250°C and 280°C, respectively. The oven temperature was set and held at 40°C for a period of 2 minutes, then gradually increased at a rate of 10°C/min to 130°C, with the final hold time set for 1 minute. An analytical method for the quantitative analysis of BCM was developed, optimized and validated. Validation of the analytical method commenced over a period of three days, and focussed the following validation parameters: Accuracy, precision, and ruggedness. Statistical evaluation of the results obtained for precision showed that the error between individual injections is less than 2 percent for each component. However, ANOVA analysis showed a significant difference between the mean response factors obtained in the three day period (p-value < 0.05). Thus we could conclude that the response factors had to be determined on each day before quantitatively analyzing samples. The accuracy of the analytical method was assessed by using the percent recovery method. Results obtained showed that a mean percent recovery of 100.18 percent was obtained for BCM, with the absolute bias = 0.0004, and the percent bias = 0.18 percent. Hence the 95 confidence intervals for the percent recovery and percent bias are given by: (Lz, Uz) = (100.56 percent percent 102.15 percent), 13 (LPB, UPB) = (0.56 percent, 2.15 percent), respectively. Since the 95 percent confidence interval for the percent recovery contains 100, or equivalently, the 95 percent confidence interval for percent bias contains 0, the assay method is considered accurate and validated for BCM. In the same manner the accuracy and percent recovery for DCM and DBM was evaluated. The method was found to be accurate and validated for DBM, however, slightly biased in determining the recovered amount of DCM. With the analytical method validated, the batch production process could be evaluated. A total of six process variables, namely reaction time, water amount, temperature, volume of the two phases, stirring rate, and catalyst concentration, were selected for the study. The effects of the individual variables were determined in the classical manner, by varying only the one of interest while keeping all others constant. The experimental data generated was fit to a quadratic response surface model. The profile plots that were obtained from this model allowed a visual representation of the effect of the six variables. The experimental results obtained showed that the reaction follows pseudo zero-order kinetics and that the rate of the reaction is directly proportional to the concentration of the catalyst. The reaction obeys the Arrhenius equation, and the relatively high activation energy of 87kJ.mol -1 signifies that the rate constant is strongly dependent on the temperature of the reaction. The results also showed that the formation of BCM is favoured by an increase in the reaction temperature, catalyst concentration, and a high organic: aqueous phase ratio. Thus the synthesis of BCM using phase transfer catalyst could be optimised, to obtain a 100 percent yield BCM, by increasing both the reaction temperature to 105°C, and the concentration of the phase transfer catalyst -benzyl triethylammonium chloride - to 5.36 mol percent. The reaction time was also reduced to 6 hours.
- Full Text:
- Date Issued: 2011
- Authors: Brooks, Lancelot L
- Date: 2011
- Subjects: Chemistry, Analytic , Fire extinguishing agents , Chemical systems , Physical science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10382 , http://hdl.handle.net/10948/d1008162 , Chemistry, Analytic , Fire extinguishing agents , Chemical systems , Physical science
- Description: The synthesis of bromochloromethane (BCM) in a batch reactor, using phase transfer catalysis, was investigated. During the synthetic procedure, sodium bromide (100.0g, 0.97mol) along with an excess amount of dichloromethane (265.0g, 3.12 mol) was charged to a reactor containing benzyl triethylammonium chloride (13 mmol), dissolved in 50 ml of water. The bench scale reactions were all carried out in a Parr 4520 bench top pressure reactor coupled to a Parr 4841 temperature controller. The method produced a 50.0 percent yield of the product BCM after a reaction time of 12 to 13 hours. The main objective for this investigation was to optimize the abovementioned reaction with respect to yield and reactor throughput. Quantitative analysis of BCM was performed on a Focus Gas Chromatograph, fitted with a flame ionization detector, and a BP20 column (30m × 0,32mm ID × 0,25 mm). Delta software, version 5.0, was applied for data collection and processing. The injector and detector port were set at 250°C and 280°C, respectively. The oven temperature was set and held at 40°C for a period of 2 minutes, then gradually increased at a rate of 10°C/min to 130°C, with the final hold time set for 1 minute. An analytical method for the quantitative analysis of BCM was developed, optimized and validated. Validation of the analytical method commenced over a period of three days, and focussed the following validation parameters: Accuracy, precision, and ruggedness. Statistical evaluation of the results obtained for precision showed that the error between individual injections is less than 2 percent for each component. However, ANOVA analysis showed a significant difference between the mean response factors obtained in the three day period (p-value < 0.05). Thus we could conclude that the response factors had to be determined on each day before quantitatively analyzing samples. The accuracy of the analytical method was assessed by using the percent recovery method. Results obtained showed that a mean percent recovery of 100.18 percent was obtained for BCM, with the absolute bias = 0.0004, and the percent bias = 0.18 percent. Hence the 95 confidence intervals for the percent recovery and percent bias are given by: (Lz, Uz) = (100.56 percent percent 102.15 percent), 13 (LPB, UPB) = (0.56 percent, 2.15 percent), respectively. Since the 95 percent confidence interval for the percent recovery contains 100, or equivalently, the 95 percent confidence interval for percent bias contains 0, the assay method is considered accurate and validated for BCM. In the same manner the accuracy and percent recovery for DCM and DBM was evaluated. The method was found to be accurate and validated for DBM, however, slightly biased in determining the recovered amount of DCM. With the analytical method validated, the batch production process could be evaluated. A total of six process variables, namely reaction time, water amount, temperature, volume of the two phases, stirring rate, and catalyst concentration, were selected for the study. The effects of the individual variables were determined in the classical manner, by varying only the one of interest while keeping all others constant. The experimental data generated was fit to a quadratic response surface model. The profile plots that were obtained from this model allowed a visual representation of the effect of the six variables. The experimental results obtained showed that the reaction follows pseudo zero-order kinetics and that the rate of the reaction is directly proportional to the concentration of the catalyst. The reaction obeys the Arrhenius equation, and the relatively high activation energy of 87kJ.mol -1 signifies that the rate constant is strongly dependent on the temperature of the reaction. The results also showed that the formation of BCM is favoured by an increase in the reaction temperature, catalyst concentration, and a high organic: aqueous phase ratio. Thus the synthesis of BCM using phase transfer catalyst could be optimised, to obtain a 100 percent yield BCM, by increasing both the reaction temperature to 105°C, and the concentration of the phase transfer catalyst -benzyl triethylammonium chloride - to 5.36 mol percent. The reaction time was also reduced to 6 hours.
- Full Text:
- Date Issued: 2011
Synthesis of novel inhibitors of 1-Deoxy-D-xylulose-5-phosphate reductoisomerase as potential anti-malarial lead compounds
- Authors: Mutorwa, Marius Kudumo
- Date: 2011
- Subjects: Antimalarials -- Development Plasmodium falciparum Malaria -- Chemotherapy Drug development Lead compounds Phosphonates Phosphonic acids Ligands
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4372 , http://hdl.handle.net/10962/d1005037
- Description: This research has focused on the development of novel substrate mimics as potential DXR inhibitors of 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), an essential enzyme in the mevalonate-independent pathway for the biosynthesis of isoprenoids in Plasmodium falciparum. DXR mediates the isomerisation and reduction of 1-deoxy-D-xylulose-5-phosphate (DOXP) into 2C-methyl-D-erithrytol 4-phosphate (MEP) and has been validated as an attractive target for the development of novel anti-malarial chemotherapeutic agents. Reaction of various amines with specially prepared 4-phosphonated crotonic acid in the presence of the peptide coupling reagent, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), has afforded a series of amido-phosphonate esters in moderate to good yields (48% - 73%) which, using a RuCl₃/CeCl₃/NaIO₄ catalyst system, have been dihydroxylated to furnish the dihydroxy-amido phosphonate ester pro-drugs; subsequent hydrolysis under microwave irradiation has afforded the corresponding phosphonic acids. A second series of potential inhibitors viz., 3-substituted aniline-derived phosphonate esters, their corresponding phosphonic acids and mono-sodium salts, have also been successfully synthesised. In these compounds, the essential functional groups are separated by one, two, three or four methylene groups, Deprotonation of the 3-substituted aniline substrates, followed by reaction with the appropriate ω-chloroalkanoyl chloride produced the ω-chloroamide intermediates, which were subjected to the Michaelis-Arbuzov reaction to afford the diethyl phosphonate esters in moderate to good yields (48% - 74%). Microwave-assisted TMSBrmediated cleavage of the phosphonate esters furnished the phosphonic acids, neutralisation of which afforded the mono-sodium salts. Furan-derived phosphate esters and phosphonic acids have been prepared as conformationally-restricted DOXP analogues. Functionalization at C-5 of the trityl-protected furan was achieved using the Vilsmeier-Haack formylation and Friedel-Crafts acylation reactions and, following de-tritylation, phosphorylation and oximation, using hydroxylamine hydrochloride, the novel oxime derivatives have been isolated as a third series of potential DXR inhibitors in very good yields (87% - 96%). Finally, in order to exploit an additional binding pocket in the PƒDXR active site, a series of N-benzylated phosphoramidic derivatives were obtained in seven steps from the starting material, diethyl phosphoramidate. The known inhibitors, fosmidomycin and its acetyl derivative FR900098, were also successfully synthesised as standards for STD-NMR binding and inhibition assays. In all, over 200 compounds (136 novel) have been prepared and appropriately characterised using 1-and 2-D NMR and IR spectroscopic analysis and, where necessary, HRMS or combustion analysis. Saturation Transfer Difference (STD) protein-NMR experiments, undertaken using selected compounds, have revealed binding of most of the ligands examined to EcDXR. Computersimulated docking studies have also been used to explore the preferred ligand-binding conformations and interactions between the ligands and essential DXR active-site residues, while DXR-enzyme inhibition assays of selected synthesised ligands have revealed certain patterns of inhibitory activity.
- Full Text:
- Date Issued: 2011
- Authors: Mutorwa, Marius Kudumo
- Date: 2011
- Subjects: Antimalarials -- Development Plasmodium falciparum Malaria -- Chemotherapy Drug development Lead compounds Phosphonates Phosphonic acids Ligands
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4372 , http://hdl.handle.net/10962/d1005037
- Description: This research has focused on the development of novel substrate mimics as potential DXR inhibitors of 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), an essential enzyme in the mevalonate-independent pathway for the biosynthesis of isoprenoids in Plasmodium falciparum. DXR mediates the isomerisation and reduction of 1-deoxy-D-xylulose-5-phosphate (DOXP) into 2C-methyl-D-erithrytol 4-phosphate (MEP) and has been validated as an attractive target for the development of novel anti-malarial chemotherapeutic agents. Reaction of various amines with specially prepared 4-phosphonated crotonic acid in the presence of the peptide coupling reagent, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), has afforded a series of amido-phosphonate esters in moderate to good yields (48% - 73%) which, using a RuCl₃/CeCl₃/NaIO₄ catalyst system, have been dihydroxylated to furnish the dihydroxy-amido phosphonate ester pro-drugs; subsequent hydrolysis under microwave irradiation has afforded the corresponding phosphonic acids. A second series of potential inhibitors viz., 3-substituted aniline-derived phosphonate esters, their corresponding phosphonic acids and mono-sodium salts, have also been successfully synthesised. In these compounds, the essential functional groups are separated by one, two, three or four methylene groups, Deprotonation of the 3-substituted aniline substrates, followed by reaction with the appropriate ω-chloroalkanoyl chloride produced the ω-chloroamide intermediates, which were subjected to the Michaelis-Arbuzov reaction to afford the diethyl phosphonate esters in moderate to good yields (48% - 74%). Microwave-assisted TMSBrmediated cleavage of the phosphonate esters furnished the phosphonic acids, neutralisation of which afforded the mono-sodium salts. Furan-derived phosphate esters and phosphonic acids have been prepared as conformationally-restricted DOXP analogues. Functionalization at C-5 of the trityl-protected furan was achieved using the Vilsmeier-Haack formylation and Friedel-Crafts acylation reactions and, following de-tritylation, phosphorylation and oximation, using hydroxylamine hydrochloride, the novel oxime derivatives have been isolated as a third series of potential DXR inhibitors in very good yields (87% - 96%). Finally, in order to exploit an additional binding pocket in the PƒDXR active site, a series of N-benzylated phosphoramidic derivatives were obtained in seven steps from the starting material, diethyl phosphoramidate. The known inhibitors, fosmidomycin and its acetyl derivative FR900098, were also successfully synthesised as standards for STD-NMR binding and inhibition assays. In all, over 200 compounds (136 novel) have been prepared and appropriately characterised using 1-and 2-D NMR and IR spectroscopic analysis and, where necessary, HRMS or combustion analysis. Saturation Transfer Difference (STD) protein-NMR experiments, undertaken using selected compounds, have revealed binding of most of the ligands examined to EcDXR. Computersimulated docking studies have also been used to explore the preferred ligand-binding conformations and interactions between the ligands and essential DXR active-site residues, while DXR-enzyme inhibition assays of selected synthesised ligands have revealed certain patterns of inhibitory activity.
- Full Text:
- Date Issued: 2011
Synthesis, characterization and application of monocarboxy-phthalocyanine-single walled carbon nanotube conjugates in electrocatalysis
- Mugadza, Tawanda, Nyokong, Tebello
- Authors: Mugadza, Tawanda , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247399 , vital:51577 , xlink:href="https://doi.org/10.1016/j.poly.2011.04.020"
- Description: In this paper we report on the synthesis, characterization and use of monocarboxy-phthalocyanine-single walled carbon nanotube conjugates in the electrocatalysis of amitrole and diuron. UV–Vis, FTIR and XRD spectroscopies were used in the characterization of cobalt(II)-tris(benzyl-mercapto)-mono(carboxyphenoxy)-phthalocyanine conjugates (CoMCPc–PA-SWCNT(linked)), while AFM was used to show changes in surface morphologies of the modified electrodes. Cyclic voltammetry and chronoamperometry were used for the electrocatalytic oxidation of amitrole and diuron on the modified glassy carbon electrode. The catalytic rate constants for amitrole and diuron were found to be 1.83 × 106 and 1.99 × 106 M−1 s−1, respectively. The linear range for both was 1.0 × 10−5–2.0 × 10−4 M, with sensitivities of 5.10 and 3.70 A mol−1 L cm−2 for amitrole and diuron, respectively. The limits of detection were estimated to be 0.14 and 0.20 μM for amitrole and diuron, respectively, using the 3δ notation.
- Full Text:
- Date Issued: 2011
- Authors: Mugadza, Tawanda , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247399 , vital:51577 , xlink:href="https://doi.org/10.1016/j.poly.2011.04.020"
- Description: In this paper we report on the synthesis, characterization and use of monocarboxy-phthalocyanine-single walled carbon nanotube conjugates in the electrocatalysis of amitrole and diuron. UV–Vis, FTIR and XRD spectroscopies were used in the characterization of cobalt(II)-tris(benzyl-mercapto)-mono(carboxyphenoxy)-phthalocyanine conjugates (CoMCPc–PA-SWCNT(linked)), while AFM was used to show changes in surface morphologies of the modified electrodes. Cyclic voltammetry and chronoamperometry were used for the electrocatalytic oxidation of amitrole and diuron on the modified glassy carbon electrode. The catalytic rate constants for amitrole and diuron were found to be 1.83 × 106 and 1.99 × 106 M−1 s−1, respectively. The linear range for both was 1.0 × 10−5–2.0 × 10−4 M, with sensitivities of 5.10 and 3.70 A mol−1 L cm−2 for amitrole and diuron, respectively. The limits of detection were estimated to be 0.14 and 0.20 μM for amitrole and diuron, respectively, using the 3δ notation.
- Full Text:
- Date Issued: 2011
Synthesis, characterization, and photophysical properties of novel ball-type dinuclear and mononuclear containing four 1, 1′-binaphthyl-8, 8′-diol bridged metallophthalocyanines with long triplet state lifetimes
- Canlıca, Mevlude, Nyokong, Tebello
- Authors: Canlıca, Mevlude , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248406 , vital:51683 , xlink:href="https://doi.org/10.1039/C0DT01749C"
- Description: The syntheses of new ball-type dinuclear Si(IV)(CH3COO)2 and Ti(IV)O phthalocyanines and two different mononuclear Zn(II) and Ti(IV)O phthalocyanines containing four 1,1′-binaphthyl-8,8′-diol substituents on the peripheral positions are described. The structures of these compounds were characterized using the elemental analyzes, UV-Vis, FT-IR, 1H NMR and mass spectroscopies. The ΦF values are 0.14, 0.10, 0.04, 0.02, 0.07; ΦT values are 0.69, 0.71, 0.85, 0.33, 0.71 for 7–11, respectively. All complexes showed very long triplet lifetimes with τT 7510, 3190, 2880, 2370, 9470 μs for 7–11 in DMSO, respectively.
- Full Text:
- Date Issued: 2011
- Authors: Canlıca, Mevlude , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248406 , vital:51683 , xlink:href="https://doi.org/10.1039/C0DT01749C"
- Description: The syntheses of new ball-type dinuclear Si(IV)(CH3COO)2 and Ti(IV)O phthalocyanines and two different mononuclear Zn(II) and Ti(IV)O phthalocyanines containing four 1,1′-binaphthyl-8,8′-diol substituents on the peripheral positions are described. The structures of these compounds were characterized using the elemental analyzes, UV-Vis, FT-IR, 1H NMR and mass spectroscopies. The ΦF values are 0.14, 0.10, 0.04, 0.02, 0.07; ΦT values are 0.69, 0.71, 0.85, 0.33, 0.71 for 7–11, respectively. All complexes showed very long triplet lifetimes with τT 7510, 3190, 2880, 2370, 9470 μs for 7–11 in DMSO, respectively.
- Full Text:
- Date Issued: 2011
Systematics, morphology, phylogeny and historical biogeography of the Mayfly family Prosopistomatidae (Ephemeroptera: Insecta) of the world
- Barber-James, Helen Margaret
- Authors: Barber-James, Helen Margaret
- Date: 2011
- Subjects: Mayflies Mayflies -- Classification Mayflies -- Morphology Mayflies -- Phylogeny Mayflies -- Geographical distribution Ephemeridae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5785 , http://hdl.handle.net/10962/d1005473
- Description: The diversity, classification and historical biogeography of the mayfly family Prosopistomatidae are explored. First, the higher classification of the Ephemeroptera is reviewed, focussing on the phylogenetic placement of the Prosopistomatidae relative to other mayfly families. All relevant literature from 1762 to 2010 is synthesized. Baetiscidae are established as the probable sister lineage of Prosopistomatidae, the two constituting the superfamily Baetiscoidea. Next, qualitative morphological variation within the Prosopistomatidae is reviewed and revised, emphasizing nymphs because imaginal specimens are few. The labium and associated structures and the hypopharynx of nymphs, and the highly-derived wing venation of the imaginal stages, are re-interpreted. The structure of the male tarsal claws changes considerably between subimago and imago, which, together with deeply scalloped ridges on male imaginal forelegs and unusual pits on the female thorax, are interpreted as providing an unusual mating mechanism. These structures provide morphological characters for species definition and phylogenetic analyses. Two approaches to species delimitation are explored. First, morphometric variation is analysed using Principal Component Analysis, revealing groupings that can be interpreted as species, although there is some overlap between them. Discriminant Function Analysis shows that head width and carapace shape have the most value in identifying nymphs of different species. The carapace of Prosopistoma nymphs is shown to grow allometrically and gradually, in contrast with that of Baetisca, indicating a difference in early ontogeny. Second, an Artificial Neural Network algorithm applied to nymphal morphological characters accurately identified species. This computer-driven artificial intelligence method has power to provide future easy-to-use electronic identification aids. Phylogenetic analysis of nymphal morphology using the parsimony method shows two clades of Prosopistomatidae, one sharing characters with the type species, Prosopistoma variegatum and the other predominating in Africa, although also occurring in Asia; these clades are named the “P. variegatum” and “African” clades, respectively. Parsimony analysis of adult morphology supports these two clades, but supertree analysis obscures the relationships, nesting the “P. variegatum” lineage within the other clade. Preliminary molecular phylogenetic analysis of the 16S rRNA, (mitochondrial) 18S rRNA and Histone-3 genes using Bayesian Inference methods does not support the two clades shown by morphology. Instead, there is a strong relationship between the European species and one African species, with the single Asian representative being most distantly related. These results are limited by lack of fresh material, patchy taxon sampling, and problems with finding suitable primers. A molecular clock program, BEAST, calibrated using fossils, suggests divergence times for the oldest crown-group Prosopistoma clade, represented by the Asian P. wouterae, of about 131 Ma, with the youngest species, the African P. crassi, of 1.21 Ma. Stem-group relationships are analysed using parsimony analysis, focussing on wing characters of the Baetiscoidea, other extant mayfly lineages, and extinct stem-group lineages. This suggests that the Baetiscoidea diverged from main-line Ephemeroptera earlier than any other extant mayfly lineage. This approach expands upon ideas hinted at by earlier scientists. Finally, historical biogeographical analysis of the distribution of known Baetiscoidea s.s. stem-group fossils implies a once Pangean distribution of the lineage. Changing palaeo-climate, catastrophic extinction events and plate tectonic movements in relation to the distribution of crown-group species are reviewed. Other approaches to historical biogeography that build on both morphological and molecular phylogenies are used to interpret disperalist and vacarianist arguments. Distribution patterns of eight unrelated freshwater organisms which share a similar distribution pattern are compared, assuming that shared patterns indicate similar historic biogeographic processes. The distribution of recent Prosopistoma species is seen to be the product of evolution resulting from both vicariance and dispersal. In conclusion, this thesis encompasses a variety of disciplines. It successfully recognises new characters and distinguishes previously unknown species. It uses new approaches to delimiting species and known methods to determine phylogeny from several angles. The analysis of stem-group relationships offers an insight into possible early lineage splitting within Ephemeroptera. Interpretation of historical biogeography allows for both a Gondwanan origin of Prosopistomatidae, with rafting of species on the Deccan plate to Asia, and for subsequent dispersal from Asia down to Australia and across to Europe, and possibly back to Africa.
- Full Text:
- Date Issued: 2011
- Authors: Barber-James, Helen Margaret
- Date: 2011
- Subjects: Mayflies Mayflies -- Classification Mayflies -- Morphology Mayflies -- Phylogeny Mayflies -- Geographical distribution Ephemeridae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5785 , http://hdl.handle.net/10962/d1005473
- Description: The diversity, classification and historical biogeography of the mayfly family Prosopistomatidae are explored. First, the higher classification of the Ephemeroptera is reviewed, focussing on the phylogenetic placement of the Prosopistomatidae relative to other mayfly families. All relevant literature from 1762 to 2010 is synthesized. Baetiscidae are established as the probable sister lineage of Prosopistomatidae, the two constituting the superfamily Baetiscoidea. Next, qualitative morphological variation within the Prosopistomatidae is reviewed and revised, emphasizing nymphs because imaginal specimens are few. The labium and associated structures and the hypopharynx of nymphs, and the highly-derived wing venation of the imaginal stages, are re-interpreted. The structure of the male tarsal claws changes considerably between subimago and imago, which, together with deeply scalloped ridges on male imaginal forelegs and unusual pits on the female thorax, are interpreted as providing an unusual mating mechanism. These structures provide morphological characters for species definition and phylogenetic analyses. Two approaches to species delimitation are explored. First, morphometric variation is analysed using Principal Component Analysis, revealing groupings that can be interpreted as species, although there is some overlap between them. Discriminant Function Analysis shows that head width and carapace shape have the most value in identifying nymphs of different species. The carapace of Prosopistoma nymphs is shown to grow allometrically and gradually, in contrast with that of Baetisca, indicating a difference in early ontogeny. Second, an Artificial Neural Network algorithm applied to nymphal morphological characters accurately identified species. This computer-driven artificial intelligence method has power to provide future easy-to-use electronic identification aids. Phylogenetic analysis of nymphal morphology using the parsimony method shows two clades of Prosopistomatidae, one sharing characters with the type species, Prosopistoma variegatum and the other predominating in Africa, although also occurring in Asia; these clades are named the “P. variegatum” and “African” clades, respectively. Parsimony analysis of adult morphology supports these two clades, but supertree analysis obscures the relationships, nesting the “P. variegatum” lineage within the other clade. Preliminary molecular phylogenetic analysis of the 16S rRNA, (mitochondrial) 18S rRNA and Histone-3 genes using Bayesian Inference methods does not support the two clades shown by morphology. Instead, there is a strong relationship between the European species and one African species, with the single Asian representative being most distantly related. These results are limited by lack of fresh material, patchy taxon sampling, and problems with finding suitable primers. A molecular clock program, BEAST, calibrated using fossils, suggests divergence times for the oldest crown-group Prosopistoma clade, represented by the Asian P. wouterae, of about 131 Ma, with the youngest species, the African P. crassi, of 1.21 Ma. Stem-group relationships are analysed using parsimony analysis, focussing on wing characters of the Baetiscoidea, other extant mayfly lineages, and extinct stem-group lineages. This suggests that the Baetiscoidea diverged from main-line Ephemeroptera earlier than any other extant mayfly lineage. This approach expands upon ideas hinted at by earlier scientists. Finally, historical biogeographical analysis of the distribution of known Baetiscoidea s.s. stem-group fossils implies a once Pangean distribution of the lineage. Changing palaeo-climate, catastrophic extinction events and plate tectonic movements in relation to the distribution of crown-group species are reviewed. Other approaches to historical biogeography that build on both morphological and molecular phylogenies are used to interpret disperalist and vacarianist arguments. Distribution patterns of eight unrelated freshwater organisms which share a similar distribution pattern are compared, assuming that shared patterns indicate similar historic biogeographic processes. The distribution of recent Prosopistoma species is seen to be the product of evolution resulting from both vicariance and dispersal. In conclusion, this thesis encompasses a variety of disciplines. It successfully recognises new characters and distinguishes previously unknown species. It uses new approaches to delimiting species and known methods to determine phylogeny from several angles. The analysis of stem-group relationships offers an insight into possible early lineage splitting within Ephemeroptera. Interpretation of historical biogeography allows for both a Gondwanan origin of Prosopistomatidae, with rafting of species on the Deccan plate to Asia, and for subsequent dispersal from Asia down to Australia and across to Europe, and possibly back to Africa.
- Full Text:
- Date Issued: 2011
Tailoring a lean product development framework for the South African automotive industry
- Authors: Mund, Klaudia
- Date: 2011
- Subjects: Lean manufacturing , Automobile industry and trade -- South Africa , Production management -- South Africa , Globalization
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:8792 , http://hdl.handle.net/10948/d1015737
- Description: Globalization in the automotive industry exerts enormous pressure on automotive manufacturers and forces many global companies to expand into emerging markets, which results in adopting new ways to manage product design and development. Excellence in product design and development offers an opportunity to gain competitive advantage and can be achieved by implementing Toyota´s Lean Product Development System (LPDS). Although in the last three years Toyota has been severely challenged by the global economic crisis, by a series of recalls resulting in reputation damage and also by natural disasters such as the recent tsunamis - the world can still learn from Toyota´s successes embodied in the lean concept and practices, which are integral to Toyota´s ‘way of life’. The LPDS model (Morgan & Liker 2006) has captured the attention of academics worldwide (including this researcher) thanks to the following key characteristics: shorter development times, less engineering hours involved in development, lower manufacturing costs, higher customer satisfaction and fewer defects reported. In the academic world, lean product development (LPD) is a new field of exploration and thus relevant literature and numbers of studies available are limited. However, scientists are asking questions about successful adaptation and adoption of this model to other environments beyond Toyota. Similarly, the researcher aimed in this thesis to find answers to its main research question, namely: ‘What would be a suitable LPD model for the South African automotive industry?’ South Africa (SA) is a country with a strong manufacturing tradition and although the automotive sector is the third-largest segment in the South African economy and its vehicle market is the largest on the African continent in a global perspective SA´s contribution is relatively small as it produces only 0.61percent of the global motor vehicle volume (OICA 2011). While the country strives to secure sustainable development for the automotive industry and seeks to improve its global competitiveness, companies operating in SA are currently faced with several unique challenges and problems. Lean has been expanding slowly in SA and some companies in the local automotive industry have implemented the lean concept into production areas to improve their operational excellence and performance. However, it is a search for excellence in product development (PD) that could best contribute to improved sustainability for the automotive industry and also provide an important strategic spur towards global competitiveness. The primary intention of this research was to develop an integrated LPD framework tailored for SA´s automotive industry. Considering this, it was necessary to determine current PD capabilities at domestic and international companies operating in SA´s automotive industry so as to examine levels of adaptation of LPD practices. A questionnaire survey and personal interviews involving all seven locally operating Original Equipment Manufacturers (OEMs), including Toyota, as well as 36 local automotive suppliers provided an empirical base for this investigation. This study indicates that SA plays an important supportive role in the global PD context. In spite of a strong manufacturing focus and very limited PD capabilities, SA´s automotive companies have already achieved a high level of ‘leanness’ in product engineering processes. However, on the downside, it appears that industry leaders and senior managers are sceptical about current and future capabilities and opportunities for SA in the designing and developing of global products.
- Full Text:
- Date Issued: 2011
- Authors: Mund, Klaudia
- Date: 2011
- Subjects: Lean manufacturing , Automobile industry and trade -- South Africa , Production management -- South Africa , Globalization
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:8792 , http://hdl.handle.net/10948/d1015737
- Description: Globalization in the automotive industry exerts enormous pressure on automotive manufacturers and forces many global companies to expand into emerging markets, which results in adopting new ways to manage product design and development. Excellence in product design and development offers an opportunity to gain competitive advantage and can be achieved by implementing Toyota´s Lean Product Development System (LPDS). Although in the last three years Toyota has been severely challenged by the global economic crisis, by a series of recalls resulting in reputation damage and also by natural disasters such as the recent tsunamis - the world can still learn from Toyota´s successes embodied in the lean concept and practices, which are integral to Toyota´s ‘way of life’. The LPDS model (Morgan & Liker 2006) has captured the attention of academics worldwide (including this researcher) thanks to the following key characteristics: shorter development times, less engineering hours involved in development, lower manufacturing costs, higher customer satisfaction and fewer defects reported. In the academic world, lean product development (LPD) is a new field of exploration and thus relevant literature and numbers of studies available are limited. However, scientists are asking questions about successful adaptation and adoption of this model to other environments beyond Toyota. Similarly, the researcher aimed in this thesis to find answers to its main research question, namely: ‘What would be a suitable LPD model for the South African automotive industry?’ South Africa (SA) is a country with a strong manufacturing tradition and although the automotive sector is the third-largest segment in the South African economy and its vehicle market is the largest on the African continent in a global perspective SA´s contribution is relatively small as it produces only 0.61percent of the global motor vehicle volume (OICA 2011). While the country strives to secure sustainable development for the automotive industry and seeks to improve its global competitiveness, companies operating in SA are currently faced with several unique challenges and problems. Lean has been expanding slowly in SA and some companies in the local automotive industry have implemented the lean concept into production areas to improve their operational excellence and performance. However, it is a search for excellence in product development (PD) that could best contribute to improved sustainability for the automotive industry and also provide an important strategic spur towards global competitiveness. The primary intention of this research was to develop an integrated LPD framework tailored for SA´s automotive industry. Considering this, it was necessary to determine current PD capabilities at domestic and international companies operating in SA´s automotive industry so as to examine levels of adaptation of LPD practices. A questionnaire survey and personal interviews involving all seven locally operating Original Equipment Manufacturers (OEMs), including Toyota, as well as 36 local automotive suppliers provided an empirical base for this investigation. This study indicates that SA plays an important supportive role in the global PD context. In spite of a strong manufacturing focus and very limited PD capabilities, SA´s automotive companies have already achieved a high level of ‘leanness’ in product engineering processes. However, on the downside, it appears that industry leaders and senior managers are sceptical about current and future capabilities and opportunities for SA in the designing and developing of global products.
- Full Text:
- Date Issued: 2011
Tailoring a lean product development framework for the South African automotive industry
- Authors: Mund, Klaudia
- Date: 2011
- Subjects: Lean manufacturing , Automobile industry and trade -- South Africa , Production management -- South Africa , Globalization
- Language: English
- Type: Thesis , Doctoral , DTech (Operations Management)
- Identifier: vital:9605 , http://hdl.handle.net/10948/1660 , Lean manufacturing , Automobile industry and trade -- South Africa , Production management -- South Africa , Globalization
- Description: Globalization in the automotive industry exerts enormous pressure on automotive manufacturers and forces many global companies to expand into emerging markets, which results in adopting new ways to manage product design and development. Excellence in product design and development offers an opportunity to gain competitive advantage and can be achieved by implementing Toyota´s Lean Product Development System (LPDS). Although in the last three years Toyota has been severely challenged by the global economic crisis, by a series of recalls resulting in reputation damage and also by natural disasters such as the recent tsunamis - the world can still learn from Toyota´s successes embodied in the lean concept and practices, which are integral to Toyota´s ‘way of life’. The LPDS model (Morgan & Liker 2006) has captured the attention of academics worldwide (including this researcher) thanks to the following key characteristics: shorter development times, less engineering hours involved in development, lower manufacturing costs, higher customer satisfaction and fewer defects reported. In the academic world, lean product development (LPD) is a new field of exploration and thus relevant literature and numbers of studies available are limited. However, scientists are asking questions about successful adaptation and adoption of this model to other environments beyond Toyota. Similarly, the researcher aimed in this thesis to find answers to its main research question, namely: ‘What would be a suitable LPD model for the South African automotive industry?’ South Africa (SA) is a country with a strong manufacturing tradition and although the automotive sector is the third-largest segment in the South African economy and its vehicle market is the largest on the African continent in a global perspective SA´s contribution is relatively small as it produces only 0.61% of the global motor vehicle volume (OICA 2011). While the country strives to secure sustainable development for the automotive industry and seeks to improve its global competitiveness, companies operating in SA are currently faced with several unique challenges and problems. Lean has been expanding slowly in SA and some companies in the local automotive industry have implemented the lean concept into production areas to improve their operational excellence and performance. However, it is a search for excellence in product development (PD) that could best contribute to improved sustainability for the iv automotive industry and also provide an important strategic spur towards global competitiveness. The primary intention of this research was to develop an integrated LPD framework tailored for SA´s automotive industry. Considering this, it was necessary to determine current PD capabilities at domestic and international companies operating in SA´s automotive industry so as to examine levels of adaptation of LPD practices. A questionnaire survey and personal interviews involving all seven locally operating Original Equipment Manufacturers (OEMs), including Toyota, as well as 36 local automotive suppliers provided an empirical base for this investigation. This study indicates that SA plays an important supportive role in the global PD context. In spite of a strong manufacturing focus and very limited PD capabilities, SA´s automotive companies have already achieved a high level of ‘leanness’ in product engineering processes. However, on the downside, it appears that industry leaders and senior managers are sceptical about current and future capabilities and opportunities for SA in the designing and developing of global products.
- Full Text:
- Date Issued: 2011
- Authors: Mund, Klaudia
- Date: 2011
- Subjects: Lean manufacturing , Automobile industry and trade -- South Africa , Production management -- South Africa , Globalization
- Language: English
- Type: Thesis , Doctoral , DTech (Operations Management)
- Identifier: vital:9605 , http://hdl.handle.net/10948/1660 , Lean manufacturing , Automobile industry and trade -- South Africa , Production management -- South Africa , Globalization
- Description: Globalization in the automotive industry exerts enormous pressure on automotive manufacturers and forces many global companies to expand into emerging markets, which results in adopting new ways to manage product design and development. Excellence in product design and development offers an opportunity to gain competitive advantage and can be achieved by implementing Toyota´s Lean Product Development System (LPDS). Although in the last three years Toyota has been severely challenged by the global economic crisis, by a series of recalls resulting in reputation damage and also by natural disasters such as the recent tsunamis - the world can still learn from Toyota´s successes embodied in the lean concept and practices, which are integral to Toyota´s ‘way of life’. The LPDS model (Morgan & Liker 2006) has captured the attention of academics worldwide (including this researcher) thanks to the following key characteristics: shorter development times, less engineering hours involved in development, lower manufacturing costs, higher customer satisfaction and fewer defects reported. In the academic world, lean product development (LPD) is a new field of exploration and thus relevant literature and numbers of studies available are limited. However, scientists are asking questions about successful adaptation and adoption of this model to other environments beyond Toyota. Similarly, the researcher aimed in this thesis to find answers to its main research question, namely: ‘What would be a suitable LPD model for the South African automotive industry?’ South Africa (SA) is a country with a strong manufacturing tradition and although the automotive sector is the third-largest segment in the South African economy and its vehicle market is the largest on the African continent in a global perspective SA´s contribution is relatively small as it produces only 0.61% of the global motor vehicle volume (OICA 2011). While the country strives to secure sustainable development for the automotive industry and seeks to improve its global competitiveness, companies operating in SA are currently faced with several unique challenges and problems. Lean has been expanding slowly in SA and some companies in the local automotive industry have implemented the lean concept into production areas to improve their operational excellence and performance. However, it is a search for excellence in product development (PD) that could best contribute to improved sustainability for the iv automotive industry and also provide an important strategic spur towards global competitiveness. The primary intention of this research was to develop an integrated LPD framework tailored for SA´s automotive industry. Considering this, it was necessary to determine current PD capabilities at domestic and international companies operating in SA´s automotive industry so as to examine levels of adaptation of LPD practices. A questionnaire survey and personal interviews involving all seven locally operating Original Equipment Manufacturers (OEMs), including Toyota, as well as 36 local automotive suppliers provided an empirical base for this investigation. This study indicates that SA plays an important supportive role in the global PD context. In spite of a strong manufacturing focus and very limited PD capabilities, SA´s automotive companies have already achieved a high level of ‘leanness’ in product engineering processes. However, on the downside, it appears that industry leaders and senior managers are sceptical about current and future capabilities and opportunities for SA in the designing and developing of global products.
- Full Text:
- Date Issued: 2011
Talent management by the East London IDZ to lever the competitive edge
- Authors: Swana, Leonard Sandile
- Date: 2011
- Subjects: Investments, Foreign , Ability -- Economic aspects -- South Africa -- East London
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8795 , http://hdl.handle.net/10948/d1015982
- Description: Talent in the field of attraction of Foreign Direct Investment (FDI) is scarce in South Africa, especially in the Eastern Cape, due to the history of exclusion of South Africa from world economic participation, prior to 1994. In order for the ELIDZ to achieve its mandate of FDI attraction, job creation and economic growth, talent management has to be a key aspect in the boardroom discussions and strategic planning sessions. The purpose of this study is to investigate the effective use of talent management by the East London IDZ to leverage the competitive edge of the ELIDZ in the business of attracting Foreign Direct Investment into South Africa, and also of competing against the world’s Economic Processing Zones (EPZ’s) and Free Trade Zones (FTZ’s). According to Holbeche (2009:166), talent consists of those individuals who can make a difference to organisational performance, either through their immediate contribution, or, in the longer term, by demonstrating the highest level of potential. For the purpose of this study, talent management is defined as the systematic attraction, identification, development, engagement / retention and deployment of those individuals with high potential who are of particular value to an organisation. The literature reviewed pointed out very clearly that organisations that have properly developed, implemented and managed talent management strategies enjoy high levels of motivation, innovation and creativity, lesser levels of staff turn-over, high employee performance, superior productivity and mostly a competitive advantage in their league. The East London IDZ study response enjoyed a rate of 40 out of 54 employees who received questionnaires and returned them by the due date. The responses represented a total of 74.1 percent, and this level of response is attributed to the fact that by the end of May 2011, the ELIDZ had just undergone an Organisational Re-structuring. The current status quo of the ELIDZ, based on the views as reflected in this study ,is very compromising for an organisation that aims to compete in the global space for the attraction and retention of foreign direct investment (FDI’s), and the global competitiveness based on the talent available. The overall picture depicted by the empirical results suggests that there are critical gaps for which the ELIDZ Executive Management and Board need to craft solutions, if competitiveness is going to be taken seriously in the near and long-term future.
- Full Text:
- Date Issued: 2011
- Authors: Swana, Leonard Sandile
- Date: 2011
- Subjects: Investments, Foreign , Ability -- Economic aspects -- South Africa -- East London
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8795 , http://hdl.handle.net/10948/d1015982
- Description: Talent in the field of attraction of Foreign Direct Investment (FDI) is scarce in South Africa, especially in the Eastern Cape, due to the history of exclusion of South Africa from world economic participation, prior to 1994. In order for the ELIDZ to achieve its mandate of FDI attraction, job creation and economic growth, talent management has to be a key aspect in the boardroom discussions and strategic planning sessions. The purpose of this study is to investigate the effective use of talent management by the East London IDZ to leverage the competitive edge of the ELIDZ in the business of attracting Foreign Direct Investment into South Africa, and also of competing against the world’s Economic Processing Zones (EPZ’s) and Free Trade Zones (FTZ’s). According to Holbeche (2009:166), talent consists of those individuals who can make a difference to organisational performance, either through their immediate contribution, or, in the longer term, by demonstrating the highest level of potential. For the purpose of this study, talent management is defined as the systematic attraction, identification, development, engagement / retention and deployment of those individuals with high potential who are of particular value to an organisation. The literature reviewed pointed out very clearly that organisations that have properly developed, implemented and managed talent management strategies enjoy high levels of motivation, innovation and creativity, lesser levels of staff turn-over, high employee performance, superior productivity and mostly a competitive advantage in their league. The East London IDZ study response enjoyed a rate of 40 out of 54 employees who received questionnaires and returned them by the due date. The responses represented a total of 74.1 percent, and this level of response is attributed to the fact that by the end of May 2011, the ELIDZ had just undergone an Organisational Re-structuring. The current status quo of the ELIDZ, based on the views as reflected in this study ,is very compromising for an organisation that aims to compete in the global space for the attraction and retention of foreign direct investment (FDI’s), and the global competitiveness based on the talent available. The overall picture depicted by the empirical results suggests that there are critical gaps for which the ELIDZ Executive Management and Board need to craft solutions, if competitiveness is going to be taken seriously in the near and long-term future.
- Full Text:
- Date Issued: 2011
Tartarus: A honeypot based malware tracking and mitigation framework
- Hunter, Samuel O, Irwin, Barry V W
- Authors: Hunter, Samuel O , Irwin, Barry V W
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428629 , vital:72525 , https://d1wqtxts1xzle7.cloudfront.net/96055420/Hunter-libre.pdf?1671479103=andresponse-content-disposi-tion=inline%3B+filename%3DTartarus_A_honeypot_based_malware_tracki.pdfandExpires=1714722666andSignature=JtPpR-IoAXILqsIJSlmCEvn6yyytE17YLQBeFJRKD5aBug-EbLxFpEGDf4GtQXHbxHvR4~E-b5QtMs1H6ruSYDti9fIHenRbLeepZTx9jYj92to3qZjy7UloigYbQuw0Y6sN95jI7d4HX-Xkspbz0~DsnzwFmLGopg7j9RZSHqpSpI~fBvlml3QQ2rLCm4aB9u8tSW8du5u~FiJgiLHNgJaPzEOzy4~yfKkXBh--LTFdgeAVYxQbOESGGh9k5bc-LDJhQ6dD5HpXsM3wKJvYuVyU6m83vT2scogVgKHIr-t~XuiqL35PfI3hs2c~ZO0TH4hCqwiNMHQ8GCYsLvllsA__andKey-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: On a daily basis many of the hosts connected to the Internet experi-ence continuous probing and attack from malicious entities. Detection and defence from these malicious entities has primarily been the con-cern of Intrusion Detection Systems, Intrusion Prevention Systems and Anti-Virus software. These systems rely heavily on known signatures to detect nefarious traffic. Due to the reliance on known malicious signa-tures, these systems have been at a serious disadvantage when it comes to detecting new, never before seen malware. This paper will introduce Tartarus which is a malware tracking and mitigation frame-work that makes use of honeypot technology in order to detect mali-cious traffic. Tartarus implements a dynamic quarantine technique to mitigate the spread of self propagating malware on a production net-work. In order to better understand the spread and impact of internet worms Tartarus is used to construct a detailed demographic of poten-tially malicious hosts on the internet. This host demographic is in turn used as a blacklist for firewall rule creation. The sources of malicious traffic is then illustrated through the use of a geolocation based visuali-sation.
- Full Text:
- Date Issued: 2011
- Authors: Hunter, Samuel O , Irwin, Barry V W
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428629 , vital:72525 , https://d1wqtxts1xzle7.cloudfront.net/96055420/Hunter-libre.pdf?1671479103=andresponse-content-disposi-tion=inline%3B+filename%3DTartarus_A_honeypot_based_malware_tracki.pdfandExpires=1714722666andSignature=JtPpR-IoAXILqsIJSlmCEvn6yyytE17YLQBeFJRKD5aBug-EbLxFpEGDf4GtQXHbxHvR4~E-b5QtMs1H6ruSYDti9fIHenRbLeepZTx9jYj92to3qZjy7UloigYbQuw0Y6sN95jI7d4HX-Xkspbz0~DsnzwFmLGopg7j9RZSHqpSpI~fBvlml3QQ2rLCm4aB9u8tSW8du5u~FiJgiLHNgJaPzEOzy4~yfKkXBh--LTFdgeAVYxQbOESGGh9k5bc-LDJhQ6dD5HpXsM3wKJvYuVyU6m83vT2scogVgKHIr-t~XuiqL35PfI3hs2c~ZO0TH4hCqwiNMHQ8GCYsLvllsA__andKey-Pair-Id=APKAJLOHF5GGSLRBV4ZA
- Description: On a daily basis many of the hosts connected to the Internet experi-ence continuous probing and attack from malicious entities. Detection and defence from these malicious entities has primarily been the con-cern of Intrusion Detection Systems, Intrusion Prevention Systems and Anti-Virus software. These systems rely heavily on known signatures to detect nefarious traffic. Due to the reliance on known malicious signa-tures, these systems have been at a serious disadvantage when it comes to detecting new, never before seen malware. This paper will introduce Tartarus which is a malware tracking and mitigation frame-work that makes use of honeypot technology in order to detect mali-cious traffic. Tartarus implements a dynamic quarantine technique to mitigate the spread of self propagating malware on a production net-work. In order to better understand the spread and impact of internet worms Tartarus is used to construct a detailed demographic of poten-tially malicious hosts on the internet. This host demographic is in turn used as a blacklist for firewall rule creation. The sources of malicious traffic is then illustrated through the use of a geolocation based visuali-sation.
- Full Text:
- Date Issued: 2011
tea time
- Authors: Leff, Carol W
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , poem
- Identifier: http://hdl.handle.net/10962/462919 , vital:76347 , ISBN 0028-4459 , https://journals.co.za/doi/epdf/10.10520/EJC125847
- Description: New Coin is one of South Africa's most established and influential poetry journals. It publishes poetry, and poetry-related reviews, commentary and interviews. New Coin places a particular emphasis on evolving forms and experimental use of the English language in poetry in the South African context. In this sense it has traced the most exciting trends and currents in contemporary poetry in South Africa for a decade of more. The journal is published twice a year in June and December by the Institute for the Study of English in Africa (ISEA), Rhodes University.
- Full Text:
- Date Issued: 2011
- Authors: Leff, Carol W
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , poem
- Identifier: http://hdl.handle.net/10962/462919 , vital:76347 , ISBN 0028-4459 , https://journals.co.za/doi/epdf/10.10520/EJC125847
- Description: New Coin is one of South Africa's most established and influential poetry journals. It publishes poetry, and poetry-related reviews, commentary and interviews. New Coin places a particular emphasis on evolving forms and experimental use of the English language in poetry in the South African context. In this sense it has traced the most exciting trends and currents in contemporary poetry in South Africa for a decade of more. The journal is published twice a year in June and December by the Institute for the Study of English in Africa (ISEA), Rhodes University.
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- Date Issued: 2011
Teacher professional development with an Education for Sustainable Development focus in South Africa: Development of a network, curriculum framework and resources for teacher education
- Authors: Lotz-Sisitka, Heila
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128949 , vital:36193 , https://www.ajol.info/index.php/sajee/article/view/122242
- Description: This national case study reports on the development of a national network, curriculum framework and resources for teacher education, with specific focus on the inclusion of environment and sustainability, also known as education for sustainable development (ESD) in the South African teacher education system. It reviews and reports on the history of environment and sustainability education in teacher education, and from this, the national case study begins to conceptualise a new approach to environment and sustainability teacher education within a new curriculum policy environment, and a new teacher education and development policy environment.Action research case study methodology is used to document the first phase of the emergence of this network, and this report covers Phase 1 of the initiative, which covers formation of the network, review of previous practices, three conceptual development pilot studies undertaken in both in-service and pre-service teacher education environments and a piloting of a ‘Train the Trainers’ or ‘Educate the Teacher Educators’ programme, which complements and extends the actual teacher education and development (TED) programme under development.The study highlights critical insights of relevance to the shift to a content referenced curriculum in South Africa, and shows how the ‘knowledge mix’ which forms the foundation of the new Teacher Education Qualifications Framework can be engaged. It also highlights some features of the changing knowledge environment, and what dominant knowledge practices are in environment and sustainability-related teaching and teacher education practices, opening these up for further scrutiny. It raises concerns that dominant knowledge work, while integrating a range of forms of knowledge (as is expected of the teacher education system under the new policy), tends to be limited by content on problems and issues for raising awareness, and fails to develop deeper conceptual depth and understanding of environment and sustainability, as issues based knowledge dominates. Similarly, it fails to support social innovation as a response to environment and sustainability concerns, as awareness raising dominates in dominant knowledge work. The study provides a revised conceptual framework for the Teacher Development Network (TEDN) programme, with guidance on key elements necessary to take the programme forward in Phase 2.
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- Date Issued: 2011
- Authors: Lotz-Sisitka, Heila
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128949 , vital:36193 , https://www.ajol.info/index.php/sajee/article/view/122242
- Description: This national case study reports on the development of a national network, curriculum framework and resources for teacher education, with specific focus on the inclusion of environment and sustainability, also known as education for sustainable development (ESD) in the South African teacher education system. It reviews and reports on the history of environment and sustainability education in teacher education, and from this, the national case study begins to conceptualise a new approach to environment and sustainability teacher education within a new curriculum policy environment, and a new teacher education and development policy environment.Action research case study methodology is used to document the first phase of the emergence of this network, and this report covers Phase 1 of the initiative, which covers formation of the network, review of previous practices, three conceptual development pilot studies undertaken in both in-service and pre-service teacher education environments and a piloting of a ‘Train the Trainers’ or ‘Educate the Teacher Educators’ programme, which complements and extends the actual teacher education and development (TED) programme under development.The study highlights critical insights of relevance to the shift to a content referenced curriculum in South Africa, and shows how the ‘knowledge mix’ which forms the foundation of the new Teacher Education Qualifications Framework can be engaged. It also highlights some features of the changing knowledge environment, and what dominant knowledge practices are in environment and sustainability-related teaching and teacher education practices, opening these up for further scrutiny. It raises concerns that dominant knowledge work, while integrating a range of forms of knowledge (as is expected of the teacher education system under the new policy), tends to be limited by content on problems and issues for raising awareness, and fails to develop deeper conceptual depth and understanding of environment and sustainability, as issues based knowledge dominates. Similarly, it fails to support social innovation as a response to environment and sustainability concerns, as awareness raising dominates in dominant knowledge work. The study provides a revised conceptual framework for the Teacher Development Network (TEDN) programme, with guidance on key elements necessary to take the programme forward in Phase 2.
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- Date Issued: 2011
Teacher's attitudes towards inclusive education in junior secondary schools at Butterworth education district
- Authors: Kwababa, Masibulele Lennox
- Date: 2011
- Subjects: Inclusive education -- Education
- Language: English
- Type: Thesis , Masters , M Ed
- Identifier: vital:18426 , http://hdl.handle.net/11260/d1006963
- Description: The purpose of the study was to assess the attitudes of teachers towards inclusive education and also the factors that influence such attitudes in Junior Secondary Schools in the Butterworth Education District (BED) in the Eastern Cape Province. The study was mainly focused on circuit 7 in which most urban and rural schools existed. Quantitative research methods were used. Survey design was used to conduct the study. The population of teachers of circuit number 7 was three hundred and forty eight (348). Then thirty percent (30%) of that population was calculated to form the sample. The sample was constituted by 104 teachers. Stratified sample was used to select the sample. This means that there were 52 male teachers and also 52 female teachers in the sample. Questionnaires which were designed by the researcher were used to gather data from public Junior Secondary School teachers. The questionnaires had Likert scale of 4 points to allow participants to express their extent of agreement or disagreement with the statements. The questionnaires consisted of 3 sections, biographical information of the participants, 30 statements about inclusive education and the last section consisted of one open-ended question. The questionnaires were pilot tested using the sample which was constituted by 12 teachers, 6 were males and 6 were females. Distribution and collection of questionnaires to and from teachers took five weeks. The collected data were analyzed using Statistical Package for the Social Science (SPSS) version 17 for Microsoft word. The nominal and ordinal scales were used to code the data. The analyzed data were presented in the form of numbers in tables. The researcher interpreted the data. The findings of the study showed that the majority of teachers were positive about inclusive education although they cited lack of training, resources and facilities for inclusive education.
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- Date Issued: 2011
- Authors: Kwababa, Masibulele Lennox
- Date: 2011
- Subjects: Inclusive education -- Education
- Language: English
- Type: Thesis , Masters , M Ed
- Identifier: vital:18426 , http://hdl.handle.net/11260/d1006963
- Description: The purpose of the study was to assess the attitudes of teachers towards inclusive education and also the factors that influence such attitudes in Junior Secondary Schools in the Butterworth Education District (BED) in the Eastern Cape Province. The study was mainly focused on circuit 7 in which most urban and rural schools existed. Quantitative research methods were used. Survey design was used to conduct the study. The population of teachers of circuit number 7 was three hundred and forty eight (348). Then thirty percent (30%) of that population was calculated to form the sample. The sample was constituted by 104 teachers. Stratified sample was used to select the sample. This means that there were 52 male teachers and also 52 female teachers in the sample. Questionnaires which were designed by the researcher were used to gather data from public Junior Secondary School teachers. The questionnaires had Likert scale of 4 points to allow participants to express their extent of agreement or disagreement with the statements. The questionnaires consisted of 3 sections, biographical information of the participants, 30 statements about inclusive education and the last section consisted of one open-ended question. The questionnaires were pilot tested using the sample which was constituted by 12 teachers, 6 were males and 6 were females. Distribution and collection of questionnaires to and from teachers took five weeks. The collected data were analyzed using Statistical Package for the Social Science (SPSS) version 17 for Microsoft word. The nominal and ordinal scales were used to code the data. The analyzed data were presented in the form of numbers in tables. The researcher interpreted the data. The findings of the study showed that the majority of teachers were positive about inclusive education although they cited lack of training, resources and facilities for inclusive education.
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- Date Issued: 2011
Teaching reading in Rukwangali in four Grade 3 Namibian classrooms : a case study
- Authors: Siyave, Theresia Nerumbu
- Date: 2011
- Subjects: Reading (Elementary) -- Namibia Reading teachers -- Training of -- Namibia Kwangali language -- Study and teaching (Elementary) -- Namibia Literacy -- Study and teaching (Elementary) -- Namibia Native language and education -- Study and teaching (Elementary) -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1798 , http://hdl.handle.net/10962/d1003683
- Description: This study aims to explore four grade 3 teachers’ understanding of teaching reading in Rukwangali, a home language in Namibia in Kavango region and to observe the strategies they use as well as the activities they set for their learners. During my School Based Studies (SBS), I noticed that learners were not reading with understanding. My interest was also stimulated by a study carried out in Namibia that found that the literacy levels for Namibian learners were poor compared to those of other African countries. This is a qualitative case study carried out within an interpretive paradigm. It seeks to understand the meaning that people attached to human actions. I selected the participants purposefully and in terms of convenience, as all three schools selected are situated in Rundu, the town in which I work as a college lecturer. The research tools I employed were semi-structured interviews, document analysis, classroom observation, and stimulated recall discussions on the lessons I observed. I used a variety of methods to triangulate data and enhance validity. This study reveals that teachers use multiple methods to teach reading. These methods include phonics and syllabification to help struggling learners to decode difficult and long (polysyllabic) words and the look-and-say method for whole word recognition and meaning making at word and sentence level. In addition, they also use the thematic approach to teaching and learning to expand learners’ vocabulary and enhance their understanding of the texts they read and to make their lessons learnercentred. However, the problems of language, lack of reading books written in Rukwangali and large class sizes constrain the teachers from teaching in a more learner-centred way. Therefore, the study gives some tentative recommendations to remedy this situation.
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- Date Issued: 2011
- Authors: Siyave, Theresia Nerumbu
- Date: 2011
- Subjects: Reading (Elementary) -- Namibia Reading teachers -- Training of -- Namibia Kwangali language -- Study and teaching (Elementary) -- Namibia Literacy -- Study and teaching (Elementary) -- Namibia Native language and education -- Study and teaching (Elementary) -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1798 , http://hdl.handle.net/10962/d1003683
- Description: This study aims to explore four grade 3 teachers’ understanding of teaching reading in Rukwangali, a home language in Namibia in Kavango region and to observe the strategies they use as well as the activities they set for their learners. During my School Based Studies (SBS), I noticed that learners were not reading with understanding. My interest was also stimulated by a study carried out in Namibia that found that the literacy levels for Namibian learners were poor compared to those of other African countries. This is a qualitative case study carried out within an interpretive paradigm. It seeks to understand the meaning that people attached to human actions. I selected the participants purposefully and in terms of convenience, as all three schools selected are situated in Rundu, the town in which I work as a college lecturer. The research tools I employed were semi-structured interviews, document analysis, classroom observation, and stimulated recall discussions on the lessons I observed. I used a variety of methods to triangulate data and enhance validity. This study reveals that teachers use multiple methods to teach reading. These methods include phonics and syllabification to help struggling learners to decode difficult and long (polysyllabic) words and the look-and-say method for whole word recognition and meaning making at word and sentence level. In addition, they also use the thematic approach to teaching and learning to expand learners’ vocabulary and enhance their understanding of the texts they read and to make their lessons learnercentred. However, the problems of language, lack of reading books written in Rukwangali and large class sizes constrain the teachers from teaching in a more learner-centred way. Therefore, the study gives some tentative recommendations to remedy this situation.
- Full Text:
- Date Issued: 2011
Teaching struggling adolescent readers in Namibia : a case study
- Authors: Simanga, Elizabeth Miyaze
- Date: 2011
- Subjects: Reading (Secondary) -- Namibia Reading comprehension -- Study and teaching (Secondary) -- Namibia Reading -- Remedial teaching -- Namibia Reading teachers -- Training of -- Namibia Second language acquisition -- Namibia English language -- Study and teaching -- Foreign speakers -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1876 , http://hdl.handle.net/10962/d1005639
- Description: Though research has been conducted on many issues since Namibia's independence in 1990, none of these studies has investigated how English Second Language (ESL) teachers teach and support struggling adolescent readers (SARs) to read. Utilising qualitative research techniques such as classroom observations, semi-structured interviews and document analysis, this case study looked at strategies, methods, and resources used by five ESL secondary school teachers to teach SARs to read in two regions in Namibia, Caprivi and Otjozondjupa regions. Two of the five participants were male teachers. The presence of SARs in the classes observed was established by using informal methods such as the ESL teachers' experience (Caprivi region), while a sample of questions from PIRLS 2001 (Mullis, Martin, Gonzalez, & Kennedy (2003) was compiled to form a test used in the Otjozondjupa region. The findings show that despite undergoing initial teacher training and majoring in English, the five ESL secondary school teachers were not trained to teach SARs either how to read or how to support them. In addition, the study found that there was a shortage of reading materials in all five selected schools.
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- Date Issued: 2011
- Authors: Simanga, Elizabeth Miyaze
- Date: 2011
- Subjects: Reading (Secondary) -- Namibia Reading comprehension -- Study and teaching (Secondary) -- Namibia Reading -- Remedial teaching -- Namibia Reading teachers -- Training of -- Namibia Second language acquisition -- Namibia English language -- Study and teaching -- Foreign speakers -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1876 , http://hdl.handle.net/10962/d1005639
- Description: Though research has been conducted on many issues since Namibia's independence in 1990, none of these studies has investigated how English Second Language (ESL) teachers teach and support struggling adolescent readers (SARs) to read. Utilising qualitative research techniques such as classroom observations, semi-structured interviews and document analysis, this case study looked at strategies, methods, and resources used by five ESL secondary school teachers to teach SARs to read in two regions in Namibia, Caprivi and Otjozondjupa regions. Two of the five participants were male teachers. The presence of SARs in the classes observed was established by using informal methods such as the ESL teachers' experience (Caprivi region), while a sample of questions from PIRLS 2001 (Mullis, Martin, Gonzalez, & Kennedy (2003) was compiled to form a test used in the Otjozondjupa region. The findings show that despite undergoing initial teacher training and majoring in English, the five ESL secondary school teachers were not trained to teach SARs either how to read or how to support them. In addition, the study found that there was a shortage of reading materials in all five selected schools.
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- Date Issued: 2011
Tebello Nyokong "As chemists, we are designers"
- Authors: Nolan, Cathy
- Date: 2011
- Language: English
- Type: Article , text
- Identifier: vital:7201 , http://hdl.handle.net/10962/d1006385
- Description: What is the common thread running through denim jeans, cancer and pesticides? None springs to mind, yet when chemist Tebello Nyokong describes her fascinating research, a link begins to emerge: light. A specialist in nanochemistry, Nyokong is using laser in ways that could revolutionize not only the diagnosis and treatment of cancer but also water purification.
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- Date Issued: 2011
- Authors: Nolan, Cathy
- Date: 2011
- Language: English
- Type: Article , text
- Identifier: vital:7201 , http://hdl.handle.net/10962/d1006385
- Description: What is the common thread running through denim jeans, cancer and pesticides? None springs to mind, yet when chemist Tebello Nyokong describes her fascinating research, a link begins to emerge: light. A specialist in nanochemistry, Nyokong is using laser in ways that could revolutionize not only the diagnosis and treatment of cancer but also water purification.
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- Date Issued: 2011
Tebello Nyokong 'As chemists, we are designers'
- Authors: Nolan, Cathy
- Date: 2011
- Subjects: Nyokong, Tebello , L’Oreal–UNESCO Awards for Women in Science
- Language: English
- Type: Article , text
- Identifier: vital:7183 , http://hdl.handle.net/10962/d1006272 , Nyokong, Tebello , L’Oreal–UNESCO Awards for Women in Science
- Description: What is the common thread running through denim jeans, cancer and pesticides? None springs to mind, yet when chemist Tebello Nyokong describes her fascinating research, a link begins to emerge: light. A specialist in nanochemistry, Nyokong is using laser in ways that could revolutionize not only the diagnosis and treatment of cancer but also water purification. Born in Lesotho, Tebello Nyokong is Professor of Medicinal Chemistry and Nanotechnology at Rhodes University in South Africa and Director of the Nanotechnology Innovation Centre for Sensors (Mintek). In 2009, she was one of the five Laureates of the 2009 L’Oreal–UNESCO Awards for Women in Science.
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- Date Issued: 2011
- Authors: Nolan, Cathy
- Date: 2011
- Subjects: Nyokong, Tebello , L’Oreal–UNESCO Awards for Women in Science
- Language: English
- Type: Article , text
- Identifier: vital:7183 , http://hdl.handle.net/10962/d1006272 , Nyokong, Tebello , L’Oreal–UNESCO Awards for Women in Science
- Description: What is the common thread running through denim jeans, cancer and pesticides? None springs to mind, yet when chemist Tebello Nyokong describes her fascinating research, a link begins to emerge: light. A specialist in nanochemistry, Nyokong is using laser in ways that could revolutionize not only the diagnosis and treatment of cancer but also water purification. Born in Lesotho, Tebello Nyokong is Professor of Medicinal Chemistry and Nanotechnology at Rhodes University in South Africa and Director of the Nanotechnology Innovation Centre for Sensors (Mintek). In 2009, she was one of the five Laureates of the 2009 L’Oreal–UNESCO Awards for Women in Science.
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- Date Issued: 2011