Lived bodies: women’s experience of sex and gender
- Authors: Lothian, Julie-Anne
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/69445 , vital:29538
- Description: This thesis will discuss the category of women, as a social group, through a phenomenological understanding of women’s subjective experiences. In arguing for the phenomenological perspective of the lived body, I show the ways in which other conceptions of women’s embodied subjectivity ultimately fail to provide comprehensive accounts of the lived experience of being a woman. I begin with an investigation into how biological determinists hypothesise women’s bodies as sexed. I then move to respond to Judith Butler’s poststructuralist feminist account of the gendered body. Finally, I argue that the embodied experience of being a woman is best explained as an ambiguous relationship between socially constructed expectations of femininity and biological materiality.
- Full Text:
- Date Issued: 2014
- Authors: Lothian, Julie-Anne
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/69445 , vital:29538
- Description: This thesis will discuss the category of women, as a social group, through a phenomenological understanding of women’s subjective experiences. In arguing for the phenomenological perspective of the lived body, I show the ways in which other conceptions of women’s embodied subjectivity ultimately fail to provide comprehensive accounts of the lived experience of being a woman. I begin with an investigation into how biological determinists hypothesise women’s bodies as sexed. I then move to respond to Judith Butler’s poststructuralist feminist account of the gendered body. Finally, I argue that the embodied experience of being a woman is best explained as an ambiguous relationship between socially constructed expectations of femininity and biological materiality.
- Full Text:
- Date Issued: 2014
Thaumatotibia leucotreta and the Navel orange: ovipositional preferences and host susceptibility
- Love, C N, Hill, Martin P, Moore, Sean D
- Authors: Love, C N , Hill, Martin P , Moore, Sean D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423811 , vital:72095 , xlink:href="https://doi.org/10.1111/jen.12126"
- Description: False codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), presents a significant threat to the South African citrus industry. To limit income loss due to direct larval damage or from fruit rejection due to the phytosanitary status of this pest, additional pre-harvest control techniques are required for Navel oranges, which are known to be susceptible to T.leucotreta damage. A number of Navel orange cultivars have been developed, and differences in female T. leucotretaovi positional preference and susceptibility of cultivars to larval penetration are known to exist. Navel orange cultivars were grouped according to time of maturity (early, mid- and late season). Female T.leucotreta were subjected to choice and no-choice tests with these cultivars, measured by oviposition. Host susceptibility was tested by allowing neonate T. leucotreta larvae to penetrate the different Navel cultivars. In the early maturing group, Fischer Navels were least preferred for oviposition and the least susceptible to larval penetration. The mid- and late season maturing groupings showed limited differences in oviposition preference, although host susceptibility did appear to be an important factor in assessing the vulnerability of fruit to T. leucotreta. Despite being widely planted in South Africa, the mid-season Palmer Navels were highly susceptible to larval penetration, while for the late season cultivars, Cambria and Glen Ora Late were the least susceptible to T. leucotreta. As a result of these laboratory trials, it is recommended that farmers increase cultivation of Fischer Navels as the principal early season cultivar, avoid Palmer Navels in favour of other mid-season maturing cultivars and give preference to the late maturing Cambria and Glen Ora Late cultivars, to limit T. Leucotreta damage.
- Full Text:
- Date Issued: 2014
- Authors: Love, C N , Hill, Martin P , Moore, Sean D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423811 , vital:72095 , xlink:href="https://doi.org/10.1111/jen.12126"
- Description: False codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), presents a significant threat to the South African citrus industry. To limit income loss due to direct larval damage or from fruit rejection due to the phytosanitary status of this pest, additional pre-harvest control techniques are required for Navel oranges, which are known to be susceptible to T.leucotreta damage. A number of Navel orange cultivars have been developed, and differences in female T. leucotretaovi positional preference and susceptibility of cultivars to larval penetration are known to exist. Navel orange cultivars were grouped according to time of maturity (early, mid- and late season). Female T.leucotreta were subjected to choice and no-choice tests with these cultivars, measured by oviposition. Host susceptibility was tested by allowing neonate T. leucotreta larvae to penetrate the different Navel cultivars. In the early maturing group, Fischer Navels were least preferred for oviposition and the least susceptible to larval penetration. The mid- and late season maturing groupings showed limited differences in oviposition preference, although host susceptibility did appear to be an important factor in assessing the vulnerability of fruit to T. leucotreta. Despite being widely planted in South Africa, the mid-season Palmer Navels were highly susceptible to larval penetration, while for the late season cultivars, Cambria and Glen Ora Late were the least susceptible to T. leucotreta. As a result of these laboratory trials, it is recommended that farmers increase cultivation of Fischer Navels as the principal early season cultivar, avoid Palmer Navels in favour of other mid-season maturing cultivars and give preference to the late maturing Cambria and Glen Ora Late cultivars, to limit T. Leucotreta damage.
- Full Text:
- Date Issued: 2014
How to establish a bioinformatics postgraduate degree programme—a case study from South Africa
- Machanick, Philip, Tastan Bishop, Özlem
- Authors: Machanick, Philip , Tastan Bishop, Özlem
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124641 , vital:35641 , https://doi.10.1093/bib/bbu014
- Description: The Research Unit in Bioinformatics at Rhodes University (RUBi), South Africa, offers a Masters of Science in Bioinformatics.Growing demand for bioinformatics qualifications results in applications from across Africa.Courses aim to bridge gaps in the diverse backgrounds of students who range from biologists with no prior computing exposure to computer scientists with no biology background. The programme is evenly split between coursework and research, with diverse modules from a range of departments coveringmathematics, statistics, computer science and biology, with emphasis on application to bioinformatics research. The early focus on research helps bring students up to speed with working as a researcher. We measure success of the programme by the high rate of subsequent entry to PhD study: 10 of 14 students who completed in the years 2011-2013.
- Full Text:
- Date Issued: 2014
- Authors: Machanick, Philip , Tastan Bishop, Özlem
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124641 , vital:35641 , https://doi.10.1093/bib/bbu014
- Description: The Research Unit in Bioinformatics at Rhodes University (RUBi), South Africa, offers a Masters of Science in Bioinformatics.Growing demand for bioinformatics qualifications results in applications from across Africa.Courses aim to bridge gaps in the diverse backgrounds of students who range from biologists with no prior computing exposure to computer scientists with no biology background. The programme is evenly split between coursework and research, with diverse modules from a range of departments coveringmathematics, statistics, computer science and biology, with emphasis on application to bioinformatics research. The early focus on research helps bring students up to speed with working as a researcher. We measure success of the programme by the high rate of subsequent entry to PhD study: 10 of 14 students who completed in the years 2011-2013.
- Full Text:
- Date Issued: 2014
Trends in the TD-DFT calculations of porphyrin and phthalocyanine analogs
- Mack, John, Stone, Justin, Nyokong, Tebello
- Authors: Mack, John , Stone, Justin , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193882 , vital:45402 , xlink:href="https://doi.org/10.1142/S108842461450045X"
- Description: In 2005, Kobayashi and coworkers reported trends in the TD-DFT spectra of 17 Zn (II) porphyrinoids [J. Am. Chem. Soc. 2005; 127: 17697] that were analyzed using Michl's perimeter model as part of a study of the anomalous magnetic circular dichroism (MCD) spectroscopy of zinc tetraphenyltetraacenaphthoporphyrin. In recent years, it has become increasingly clear that TD-DFT calculations with the commonly used hybrid B3LYP exchange-correlation functional of the Gaussian software package are problematic in the B-band region of porphyrinoid spectra, since the degree of configurational interaction between the B and higher energy ππ* state appears to be significantly overestimated. The CAM-B3LYP functional is now often preferred for analyzing the optical properties of porphyrinoids, since it includes a long-range correction of the exchange potential, which incorporates an increasing fraction of Hartree–Fock (HF) exchange as the interelectronic separation increases, making it better suited for studying compounds where there is significant charge transfer in the electronic excited states. The trends in the TD-DFT calculations are reexamined with a wider range porphyrinoid compounds including several with pyrazino moieties and are found to provide a closer agreement with the experimental in the B-band region for complexes such as zinc tetraphenylporphyrin and phthalocyanine.
- Full Text:
- Date Issued: 2014
- Authors: Mack, John , Stone, Justin , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193882 , vital:45402 , xlink:href="https://doi.org/10.1142/S108842461450045X"
- Description: In 2005, Kobayashi and coworkers reported trends in the TD-DFT spectra of 17 Zn (II) porphyrinoids [J. Am. Chem. Soc. 2005; 127: 17697] that were analyzed using Michl's perimeter model as part of a study of the anomalous magnetic circular dichroism (MCD) spectroscopy of zinc tetraphenyltetraacenaphthoporphyrin. In recent years, it has become increasingly clear that TD-DFT calculations with the commonly used hybrid B3LYP exchange-correlation functional of the Gaussian software package are problematic in the B-band region of porphyrinoid spectra, since the degree of configurational interaction between the B and higher energy ππ* state appears to be significantly overestimated. The CAM-B3LYP functional is now often preferred for analyzing the optical properties of porphyrinoids, since it includes a long-range correction of the exchange potential, which incorporates an increasing fraction of Hartree–Fock (HF) exchange as the interelectronic separation increases, making it better suited for studying compounds where there is significant charge transfer in the electronic excited states. The trends in the TD-DFT calculations are reexamined with a wider range porphyrinoid compounds including several with pyrazino moieties and are found to provide a closer agreement with the experimental in the B-band region for complexes such as zinc tetraphenylporphyrin and phthalocyanine.
- Full Text:
- Date Issued: 2014
Bacterial degradation of waste coal
- Authors: Madikiza, Lwazikazi
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54576 , vital:26590
- Description: As an energy source coal has one of the largest agglomerations in the world. Consequently mining of coal creates large volumes of waste in the form of low ranks coals. The complex structure of coal makes it difficult for the microorganisms to degrade and relatively few bacteria and fungi have been shown to break down coal. This study aimed to investigate bacteria not previously known to degrade coal. In this study bacteria were isolated from hydrocarbon contaminated sites and inoculated in coal medium where coal served as the only carbon source. Three strains produced a yellow – brown supernatant after 14 d of incubation at 30 °C. Bacteria generating a yellow – brown coloured supernatant were presumed to possess coal degrading capabilities and the best performing of these bacterial species was identified using 16s rDNA as Bacillus flexus. Scanning electron microscopy showed that there was a close association between the bacterium and substrate coal. The close association of bacteria to substrate suggested that these organisms were able to maximize solubilisation. FT-IR spectroscopic analysis demonstrated the addition of single bonded compounds COOH, OH, CN and CH that were absent prior to bacterial interaction. The increase in oxygen rich regions indicated degradation of the coal substrate. Elemental analysis showed that there was a decrease in carbon content from 47 % to 24 % during the 14 day incubation period. Reduction in coal carbon content was assumed to be due to bacterial utilization for metabolism and growth particularly as untreated coal substrate showed minimal loss of carbon. Analysis of the residual culture medium revealed that there was a linear increase in humic-like substance concentration for 8 d, coincident with increased coal biosolubilisation and colour change. Laccase activity was insignificant, and at 13 d enzyme activity was only 5×10-3 U/L suggesting that B. flexus may use a different mechanism to degrade coal. Residual culture medium remaining after bacterial action on the coal substrate appeared to possess plant growth promoting activity. This soluble biodegradation product with characteristics similar to humic acid-like substances was shown to impact growth of radish cotyledons. Expansion of isolated radish cotyledons was enhanced by 140% when incubated in coal biodegradation product. In conclusion, this study has yielded B. flexus and two other unidentified bacteria, isolated from polyaromatic hydrocarbon contaminated soils, and demonstrated the ability of these microorganisms to degrade waste coal. Further studies to elucidate the mechanism of coal breakdown by B. flexus, synergies with other coal degrading microorganisms, and incorporation of bacterium into Fungcoal bioprocess technology is imminent.
- Full Text:
- Date Issued: 2014
- Authors: Madikiza, Lwazikazi
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54576 , vital:26590
- Description: As an energy source coal has one of the largest agglomerations in the world. Consequently mining of coal creates large volumes of waste in the form of low ranks coals. The complex structure of coal makes it difficult for the microorganisms to degrade and relatively few bacteria and fungi have been shown to break down coal. This study aimed to investigate bacteria not previously known to degrade coal. In this study bacteria were isolated from hydrocarbon contaminated sites and inoculated in coal medium where coal served as the only carbon source. Three strains produced a yellow – brown supernatant after 14 d of incubation at 30 °C. Bacteria generating a yellow – brown coloured supernatant were presumed to possess coal degrading capabilities and the best performing of these bacterial species was identified using 16s rDNA as Bacillus flexus. Scanning electron microscopy showed that there was a close association between the bacterium and substrate coal. The close association of bacteria to substrate suggested that these organisms were able to maximize solubilisation. FT-IR spectroscopic analysis demonstrated the addition of single bonded compounds COOH, OH, CN and CH that were absent prior to bacterial interaction. The increase in oxygen rich regions indicated degradation of the coal substrate. Elemental analysis showed that there was a decrease in carbon content from 47 % to 24 % during the 14 day incubation period. Reduction in coal carbon content was assumed to be due to bacterial utilization for metabolism and growth particularly as untreated coal substrate showed minimal loss of carbon. Analysis of the residual culture medium revealed that there was a linear increase in humic-like substance concentration for 8 d, coincident with increased coal biosolubilisation and colour change. Laccase activity was insignificant, and at 13 d enzyme activity was only 5×10-3 U/L suggesting that B. flexus may use a different mechanism to degrade coal. Residual culture medium remaining after bacterial action on the coal substrate appeared to possess plant growth promoting activity. This soluble biodegradation product with characteristics similar to humic acid-like substances was shown to impact growth of radish cotyledons. Expansion of isolated radish cotyledons was enhanced by 140% when incubated in coal biodegradation product. In conclusion, this study has yielded B. flexus and two other unidentified bacteria, isolated from polyaromatic hydrocarbon contaminated soils, and demonstrated the ability of these microorganisms to degrade waste coal. Further studies to elucidate the mechanism of coal breakdown by B. flexus, synergies with other coal degrading microorganisms, and incorporation of bacterium into Fungcoal bioprocess technology is imminent.
- Full Text:
- Date Issued: 2014
Book Review: Community of insecurity
- Authors: Magadla, Siphokazi
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298606 , vital:57720 , xlink:href="https://doi.org/10.1080/02589001.2014.936174"
- Description: Laurie Nathan's Community of Insecurity is a thoughtful engagement with the ‘establishment, evolution and effectiveness of the regional security arrangements of the Southern African Development Community (SADC)’ (1). He argues that it is of ‘great significance and irony that many of the major disputes among member states have been around the orientation and strategies of peacemaking and regional security’. Nathan's empirical claims about the SADC security architecture are drawn from his ‘insider perspective’ due to his involvement in official efforts to design a common security regime in Southern Africa, which include his service as regional security advisor to the SADC Secretariat from 1992 to 1996, to the Foreign Minister of Mozambique Pascoal Mocumbi from 1994 to 1995, to the South African Minister of Defence Joe Modise and the Deputy Minister of Defence Ronnie Kasrils between 1994 and 1999 and to the Foreign Minister of Swaziland Albert Shabangu when he oversaw the SADC Organ on Politics, Defence and Security Cooperation in 1999–2000 (12–13). This ‘insider’ view has allowed him to make a compelling challenge to current theoretical debates about SADC's status as a security community, that is, a community with an affinity amongst member states that is ‘so strong that they enjoy dependable expectations of peaceful change and thus regard the prospect of war among them as inconceivable’(129). While other commentators see SADC as either a ‘nascent’, ‘embryonic’ or ‘emerging’ security community, Nathan argues forcefully that ‘this perspective is mistaken’ as SADC continues to be demonstrative of a what he describes as a ‘community of insecurity’.
- Full Text:
- Date Issued: 2014
- Authors: Magadla, Siphokazi
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298606 , vital:57720 , xlink:href="https://doi.org/10.1080/02589001.2014.936174"
- Description: Laurie Nathan's Community of Insecurity is a thoughtful engagement with the ‘establishment, evolution and effectiveness of the regional security arrangements of the Southern African Development Community (SADC)’ (1). He argues that it is of ‘great significance and irony that many of the major disputes among member states have been around the orientation and strategies of peacemaking and regional security’. Nathan's empirical claims about the SADC security architecture are drawn from his ‘insider perspective’ due to his involvement in official efforts to design a common security regime in Southern Africa, which include his service as regional security advisor to the SADC Secretariat from 1992 to 1996, to the Foreign Minister of Mozambique Pascoal Mocumbi from 1994 to 1995, to the South African Minister of Defence Joe Modise and the Deputy Minister of Defence Ronnie Kasrils between 1994 and 1999 and to the Foreign Minister of Swaziland Albert Shabangu when he oversaw the SADC Organ on Politics, Defence and Security Cooperation in 1999–2000 (12–13). This ‘insider’ view has allowed him to make a compelling challenge to current theoretical debates about SADC's status as a security community, that is, a community with an affinity amongst member states that is ‘so strong that they enjoy dependable expectations of peaceful change and thus regard the prospect of war among them as inconceivable’(129). While other commentators see SADC as either a ‘nascent’, ‘embryonic’ or ‘emerging’ security community, Nathan argues forcefully that ‘this perspective is mistaken’ as SADC continues to be demonstrative of a what he describes as a ‘community of insecurity’.
- Full Text:
- Date Issued: 2014
“Pragmatic yet principled”: an assessment of Botswana’s Foreign Policy record as a small state
- Authors: Mahupela, Kabelo Moganegi
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/65290 , vital:28722
- Description: Expected release date-July 2019
- Full Text:
- Date Issued: 2014
- Authors: Mahupela, Kabelo Moganegi
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/65290 , vital:28722
- Description: Expected release date-July 2019
- Full Text:
- Date Issued: 2014
Formulation, development and assessment of efavirenz-loaded lipid nanocarriers
- Authors: Makoni, Pedzisai Anotida
- Date: 2014
- Subjects: Nanomedicine , Drug delivery systems , Antiretroviral agents Psychotropic effects , AIDS dementia complex
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/209981 , vital:47448
- Description: The feasibility of incorporating efavirenz (EFV) into innovative solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) using the hot high-pressure homogenization (HHPH) technique was investigated in an attempt to address the shortcomings in therapy associated with the use of conventional dosage forms. The shortcomings include the unpalatable taste of API in solution, instability in the presence of light when in solution and psychiatric side effects of the API. In particular, sustained release approaches may reduce or limit the incidence of adverse psychiatric effects of EFV and alleviate Acquired Immune Deficiency Syndrome (AIDS)-related complications such as AIDS Dementia Complex (ADC) in patients, ultimately improving their quality of life. Prior to initiating pre-formulation, formulation development and optimization studies of EFV-loaded SLN and/or NLC, Response Surface Methodology (RSM) in conjunction with central composite design (CCD), was used to develop and validate suitable methods for the quantitative determination of EFV in pharmaceutical formulations and for monitoring EFV release from SLN and/or NLC in vitro. Simple, accurate, precise, sensitive and stabilityindicating reversed phase-high performance liquid chromatography (RP-HPLC) methods with UV and electrochemical (EC) detection were developed, validated and optimized for in vitro analysis of EFV in formulations. On the basis of risk-to-benefit ratio the RP-HPLC method with UV detection was selected as the most suitable for the quantitative determination of EFV in pharmaceutical formulations, and was applied to in vitro release studies of EFV from SLN and/or NLC. Pre-formulation studies were undertaken to investigate the thermal stability of EFV so as to facilitate the selection of lipid excipients for the manufacture of nanocarriers, and to establish their compatibility with EFV. It was found that EFV was thermostable up to a temperature of approximately 200°C, indicating that HHPH could be used for the manufacture of EFV-loaded SLN and/or NLC. Lipid screening revealed that EFV is highly soluble in solid and liquid lipids, with glyceryl monostearate and Transcutol® HP showing the best solubilizing potential for EFV. Glyceryl monostearate exists in a stable β-modification prior to exposure to heat, but exists in the α-polymorphic modification following exposure to heat. It was established that the addition of Transcutol® HP to glyceryl monostearate revealed the co-existence of the α- and β’-polymorphic modifications, thereby revealing the existence of the modifications in NLC produced from the optimum lipid combination. Furthermore, an investigation of binary mixtures of EFV/glyceryl monostearate and glyceryl monostearate/Transcutol® HP, in addition to eutectic mixtures of EFV, glyceryl monostearate and Transcutol® HP, revealed no interaction between EFV and the lipids selected for the production of the nanocarriers. Due to the significantly higher solubility of EFV in Transcutol® HP than in to glyceryl monostearate, NLC are most likely to have a higher LC and EE than SLN. In addition, the existence of both the α- and β’-polymorphic modifications in the binary mixture of the lipid implies that EFV expulsion on prolonged storage is unlikely to occur from NLC when compared to SLN. Consequently formulation development and optimization studies of SLN and NLC were performed to investigate the potential to deliver EFV from a novel technology with an appropriate LC and EE for EFV. Tween®80 was selected for use in these formulations as the use of this surfactant facilitates the targeting of nanocarriers to the CNS. RSM in conjunction with a Box-Behnken Design (BBD) was used to establish the effects of process variables, such as number of homogenization cycles and pressure, in addition to formulation variables such as amount of EFV and Tween®80 on the particle size (PS), polydispersity index (PDI), zeta potential (ZP), visual assessment (VA) and release rate (RR) of EFV after 24 hours. In addition the LC and EE, degree of crystallinity and lipid modification, shape and surface morphology of the optimized batches were investigated to ensure that EFV-loaded SLN and NLC of desirable quality were produced. On the day of manufacture the mean PS and PDI of EFV-loaded SLN was 59.00 ± 23.16 nm and 0.382 ± 0.054 respectively. The mean PS and PDI of EFV-loaded NLC was 34.73 ± 0.7709 nm and 0.394 ± 0.027 respectively. The formulations were in the nanometer range and exhibited a narrow particle size distribution, as indicated by the PDI values. The ZP values for optimized SLN and NLC generated on the day of manufacture using HPLC grade water as the dispersion medium were -32.5 ± 4.99 mV and -22.4 ± 3.72 mV respectively. In addition the optimized batches of SLN and NLC revealed a decrease in crystallinity in comparison to bulk lipid material. DSC, WAXS and FT-IR revealed that EFV was molecularly dispersed in the nanocarriers. In addition EFV-loaded SLN existed in a single α-polymorphic form, whereas EFV-loaded NLC exhibited the co-existence of α- and β’-polymorphic forms. Generally SLN and NLC were spherically shaped when viewed under transmission electron microscopy (TEM) and scanning electron microscopy (SEM). On the day of manufacture the EE and LC of EFVloaded SLN was found to be 96.77 ± 0.453 % and 9.68 ± 1.772 % respectively. The EE and LC of EFV-loaded NLC was 99.93 ± 0.413 and 9.995 ± 0.672 respectively. The release profiles for the optimized formulations of SLN and NLC exhibited an initial burst release over the first 0-3 hours of testing, after which the release was sustained for up to 24 hours. The cumulative % EFV released over 24 hours was higher from SLN (91.5±3.423 %) than that observed for NLC (73.6±4.34 %). Stability studies performed for 8 weeks on the optimized batches of the SLN and the NLC were also conducted so as to ensure product quality. The formulations were assessed in terms of parameters considered benchmarks of stability, and included ZP, PS, PDI, LC and EE. Generally these parameters remained unchanged following storage for 8 weeks at 25°C/60% RH but showed considerable changes following storage for 8 weeks at 40°C/75% RH. These studies reveal that SLN and NLC when stored at 25°C/60% RH have the potential to be used as colloidal delivery systems for EFV that have the potential to protect EFV from photodegradation and sustain release into brain tissue. The latter will ultimately reduce or limit the incidence of adverse psychiatric effects and potentially alleviate AIDS-related complications such as ADC in patients with HIV/AIDS, ultimately improving their quality of life. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2014
- Full Text:
- Date Issued: 2014
- Authors: Makoni, Pedzisai Anotida
- Date: 2014
- Subjects: Nanomedicine , Drug delivery systems , Antiretroviral agents Psychotropic effects , AIDS dementia complex
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/209981 , vital:47448
- Description: The feasibility of incorporating efavirenz (EFV) into innovative solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) using the hot high-pressure homogenization (HHPH) technique was investigated in an attempt to address the shortcomings in therapy associated with the use of conventional dosage forms. The shortcomings include the unpalatable taste of API in solution, instability in the presence of light when in solution and psychiatric side effects of the API. In particular, sustained release approaches may reduce or limit the incidence of adverse psychiatric effects of EFV and alleviate Acquired Immune Deficiency Syndrome (AIDS)-related complications such as AIDS Dementia Complex (ADC) in patients, ultimately improving their quality of life. Prior to initiating pre-formulation, formulation development and optimization studies of EFV-loaded SLN and/or NLC, Response Surface Methodology (RSM) in conjunction with central composite design (CCD), was used to develop and validate suitable methods for the quantitative determination of EFV in pharmaceutical formulations and for monitoring EFV release from SLN and/or NLC in vitro. Simple, accurate, precise, sensitive and stabilityindicating reversed phase-high performance liquid chromatography (RP-HPLC) methods with UV and electrochemical (EC) detection were developed, validated and optimized for in vitro analysis of EFV in formulations. On the basis of risk-to-benefit ratio the RP-HPLC method with UV detection was selected as the most suitable for the quantitative determination of EFV in pharmaceutical formulations, and was applied to in vitro release studies of EFV from SLN and/or NLC. Pre-formulation studies were undertaken to investigate the thermal stability of EFV so as to facilitate the selection of lipid excipients for the manufacture of nanocarriers, and to establish their compatibility with EFV. It was found that EFV was thermostable up to a temperature of approximately 200°C, indicating that HHPH could be used for the manufacture of EFV-loaded SLN and/or NLC. Lipid screening revealed that EFV is highly soluble in solid and liquid lipids, with glyceryl monostearate and Transcutol® HP showing the best solubilizing potential for EFV. Glyceryl monostearate exists in a stable β-modification prior to exposure to heat, but exists in the α-polymorphic modification following exposure to heat. It was established that the addition of Transcutol® HP to glyceryl monostearate revealed the co-existence of the α- and β’-polymorphic modifications, thereby revealing the existence of the modifications in NLC produced from the optimum lipid combination. Furthermore, an investigation of binary mixtures of EFV/glyceryl monostearate and glyceryl monostearate/Transcutol® HP, in addition to eutectic mixtures of EFV, glyceryl monostearate and Transcutol® HP, revealed no interaction between EFV and the lipids selected for the production of the nanocarriers. Due to the significantly higher solubility of EFV in Transcutol® HP than in to glyceryl monostearate, NLC are most likely to have a higher LC and EE than SLN. In addition, the existence of both the α- and β’-polymorphic modifications in the binary mixture of the lipid implies that EFV expulsion on prolonged storage is unlikely to occur from NLC when compared to SLN. Consequently formulation development and optimization studies of SLN and NLC were performed to investigate the potential to deliver EFV from a novel technology with an appropriate LC and EE for EFV. Tween®80 was selected for use in these formulations as the use of this surfactant facilitates the targeting of nanocarriers to the CNS. RSM in conjunction with a Box-Behnken Design (BBD) was used to establish the effects of process variables, such as number of homogenization cycles and pressure, in addition to formulation variables such as amount of EFV and Tween®80 on the particle size (PS), polydispersity index (PDI), zeta potential (ZP), visual assessment (VA) and release rate (RR) of EFV after 24 hours. In addition the LC and EE, degree of crystallinity and lipid modification, shape and surface morphology of the optimized batches were investigated to ensure that EFV-loaded SLN and NLC of desirable quality were produced. On the day of manufacture the mean PS and PDI of EFV-loaded SLN was 59.00 ± 23.16 nm and 0.382 ± 0.054 respectively. The mean PS and PDI of EFV-loaded NLC was 34.73 ± 0.7709 nm and 0.394 ± 0.027 respectively. The formulations were in the nanometer range and exhibited a narrow particle size distribution, as indicated by the PDI values. The ZP values for optimized SLN and NLC generated on the day of manufacture using HPLC grade water as the dispersion medium were -32.5 ± 4.99 mV and -22.4 ± 3.72 mV respectively. In addition the optimized batches of SLN and NLC revealed a decrease in crystallinity in comparison to bulk lipid material. DSC, WAXS and FT-IR revealed that EFV was molecularly dispersed in the nanocarriers. In addition EFV-loaded SLN existed in a single α-polymorphic form, whereas EFV-loaded NLC exhibited the co-existence of α- and β’-polymorphic forms. Generally SLN and NLC were spherically shaped when viewed under transmission electron microscopy (TEM) and scanning electron microscopy (SEM). On the day of manufacture the EE and LC of EFVloaded SLN was found to be 96.77 ± 0.453 % and 9.68 ± 1.772 % respectively. The EE and LC of EFV-loaded NLC was 99.93 ± 0.413 and 9.995 ± 0.672 respectively. The release profiles for the optimized formulations of SLN and NLC exhibited an initial burst release over the first 0-3 hours of testing, after which the release was sustained for up to 24 hours. The cumulative % EFV released over 24 hours was higher from SLN (91.5±3.423 %) than that observed for NLC (73.6±4.34 %). Stability studies performed for 8 weeks on the optimized batches of the SLN and the NLC were also conducted so as to ensure product quality. The formulations were assessed in terms of parameters considered benchmarks of stability, and included ZP, PS, PDI, LC and EE. Generally these parameters remained unchanged following storage for 8 weeks at 25°C/60% RH but showed considerable changes following storage for 8 weeks at 40°C/75% RH. These studies reveal that SLN and NLC when stored at 25°C/60% RH have the potential to be used as colloidal delivery systems for EFV that have the potential to protect EFV from photodegradation and sustain release into brain tissue. The latter will ultimately reduce or limit the incidence of adverse psychiatric effects and potentially alleviate AIDS-related complications such as ADC in patients with HIV/AIDS, ultimately improving their quality of life. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2014
- Full Text:
- Date Issued: 2014
Editors reflect on the state of journalism: the cha(lle)nging media space
- Authors: Malila, Vanessa
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158650 , vital:40218 , https://hdl.handle.net/10520/EJC159502
- Description: Trying to understand how journalists and editors in the South African media landscape think about the work they do and the environment in which they work is not easy. However, while many of us speculate about why things are reported on in one way or another, this article gets to the heart of the issue - or the mouth - by speaking to journalists and editors about the work they do and how things have changed in the last few years within this complex institution we call the media.
- Full Text:
- Date Issued: 2014
- Authors: Malila, Vanessa
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158650 , vital:40218 , https://hdl.handle.net/10520/EJC159502
- Description: Trying to understand how journalists and editors in the South African media landscape think about the work they do and the environment in which they work is not easy. However, while many of us speculate about why things are reported on in one way or another, this article gets to the heart of the issue - or the mouth - by speaking to journalists and editors about the work they do and how things have changed in the last few years within this complex institution we call the media.
- Full Text:
- Date Issued: 2014
Tracing the ANC’s criticism of South African media: 20 years of democracy
- Authors: Malila, Vanessa
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158661 , vital:40219 , https://hdl.handle.net/10520/EJC159512
- Description: We often forget the strides that have been made in the media industry in South Africa since the end of apartheid and the repressive conditions under which the media industry operated prior to 1994. In the current context of complaints by the ANC about the lack of transformation in the industry and the poor reporting by the mainstream commercial media, the gains in ownership changes and the massive growth of the community media sector in South Africa are sometimes overshadowed. Despite a positive early relationship between the media and the ANC government, things have become progressively more difficult between these two institutions and the criticism from the ANC more vociferous in recent years.
- Full Text:
- Date Issued: 2014
- Authors: Malila, Vanessa
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158661 , vital:40219 , https://hdl.handle.net/10520/EJC159512
- Description: We often forget the strides that have been made in the media industry in South Africa since the end of apartheid and the repressive conditions under which the media industry operated prior to 1994. In the current context of complaints by the ANC about the lack of transformation in the industry and the poor reporting by the mainstream commercial media, the gains in ownership changes and the massive growth of the community media sector in South Africa are sometimes overshadowed. Despite a positive early relationship between the media and the ANC government, things have become progressively more difficult between these two institutions and the criticism from the ANC more vociferous in recent years.
- Full Text:
- Date Issued: 2014
Photophysicochemical behavior and antimicrobial activity of dihydroxosilicon tris (diaquaplatinum) octacarboxyphthalocyanine
- Managa, Muthumuni, Idowu, Mopelola A, Antunes, Edith M, Nyokong, Tebello
- Authors: Managa, Muthumuni , Idowu, Mopelola A , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241527 , vital:50947 , xlink:href="https://doi.org/10.1016/j.saa.2014.01.087"
- Description: Platination of dihydroxosilicon octacarboxyphthalocyanine (OH)2SiOCPc was successfully carried out to give dihydroxosilicon tris(diaquaplatinum)octacarboxyphthalocyanine (OH)2SiOCPc(Pt)3 conjugate. Slight blue shifting of the absorption spectrum of (OH)2SiOCPc(Pt)3 was observed on conjugation with platinum. Comparative photophysicochemical behavior and antimicrobial photo-activities of (OH)2SiOCPc(Pt)3 conjugate with (OH)2SiOCPc or Pt nanoparticles revealed that the heavy atom, Pt on the periphery of the phthalocyanine significantly enhanced its singlet oxygen generation with a quantum yield of 0.56 obtained for the (OH)2SiOCPc(Pt)3 conjugate. The (OH)2SiOCPc(Pt)3 conjugate showed highest antimicrobial activity towards Candida albicans and Escherichia coli compared to (OH)2SiOCPc and Pt nanoparticles alone under illumination.
- Full Text:
- Date Issued: 2014
- Authors: Managa, Muthumuni , Idowu, Mopelola A , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241527 , vital:50947 , xlink:href="https://doi.org/10.1016/j.saa.2014.01.087"
- Description: Platination of dihydroxosilicon octacarboxyphthalocyanine (OH)2SiOCPc was successfully carried out to give dihydroxosilicon tris(diaquaplatinum)octacarboxyphthalocyanine (OH)2SiOCPc(Pt)3 conjugate. Slight blue shifting of the absorption spectrum of (OH)2SiOCPc(Pt)3 was observed on conjugation with platinum. Comparative photophysicochemical behavior and antimicrobial photo-activities of (OH)2SiOCPc(Pt)3 conjugate with (OH)2SiOCPc or Pt nanoparticles revealed that the heavy atom, Pt on the periphery of the phthalocyanine significantly enhanced its singlet oxygen generation with a quantum yield of 0.56 obtained for the (OH)2SiOCPc(Pt)3 conjugate. The (OH)2SiOCPc(Pt)3 conjugate showed highest antimicrobial activity towards Candida albicans and Escherichia coli compared to (OH)2SiOCPc and Pt nanoparticles alone under illumination.
- Full Text:
- Date Issued: 2014
Conjugates of platinum nanoparticles with gallium tetra–(4-Carboxyphenyl) porphyrin and their use in photodynamic antimicrobial chemotherapy when in solution or embedded in electrospun fiber
- Managa, Muthumuni, Antunes, Edith M, Nyokong, Tebello
- Authors: Managa, Muthumuni , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193791 , vital:45396 , xlink:href="https://doi.org/10.1016/j.poly.2014.03.050"
- Description: The conjugation of Pt nanoparticles with ClGa(III) 5,10,15,20-tetrakis-(4-carboxyphenyl) porphyrin (ClGaTCPP) showed greater antimicrobial activity against a gram positive and drug resistant bacteria Staphylococcus aureus, than when the porphyrin was used alone. ClGaTCPP and its conjugate with platinum nanoparticle was successfully electrospun into a polystyrene polymer where the diameter ranged from 10 to 22 μm. The conjugates within the fiber still showed activity towards S. aureus.
- Full Text:
- Date Issued: 2014
- Authors: Managa, Muthumuni , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193791 , vital:45396 , xlink:href="https://doi.org/10.1016/j.poly.2014.03.050"
- Description: The conjugation of Pt nanoparticles with ClGa(III) 5,10,15,20-tetrakis-(4-carboxyphenyl) porphyrin (ClGaTCPP) showed greater antimicrobial activity against a gram positive and drug resistant bacteria Staphylococcus aureus, than when the porphyrin was used alone. ClGaTCPP and its conjugate with platinum nanoparticle was successfully electrospun into a polystyrene polymer where the diameter ranged from 10 to 22 μm. The conjugates within the fiber still showed activity towards S. aureus.
- Full Text:
- Date Issued: 2014
Factors leading to the high failure rate of grade 12 learners in the Ngqeleni area: A case study of two schools in the Ngqeleni area of the Libode mega district, Eastern Cape.
- Authors: Maqokolo, Gideon Zitobile
- Date: 2014
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/3444 , vital:43390
- Description: The study investigated the factors that lead to the high failure rate of grade 12 learners of the two high schools in the Ngqeleni area of Libode Mega District of the Eastern Cape, South Africa. The study was qualitative in nature; therefore interviews were used as the method of collecting data. Seven SMT members, four parents and four learners were, randomly selected from the two schools in the Ngqeleni area of Libode Mega District. The researcher randomly selected the participants then interviewed them. The researcher used a video recoder as an instrument to record the responses from the participants. To analyse data, the researcher transcribed the interview responses and interpreted them. The main findings of the study showed that the high failure rate was caused by the following factors: over-croweded classes, shortage of teaching and learnin~ materials, lack of parental involvement, teachers' low morale, poor learner discipline, teachers experiencing problems in implementing government policies, work-load and as such teaching becoming stressful. The researcher in his study therefore recommends that the Department of Education plans more workshops for schools to capacitate them. There should be provision for more classrooms and incentives for teachers. , Thesis (MMED) -- Faculty of Educational Sciences, 2019
- Full Text:
- Date Issued: 2014
- Authors: Maqokolo, Gideon Zitobile
- Date: 2014
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/3444 , vital:43390
- Description: The study investigated the factors that lead to the high failure rate of grade 12 learners of the two high schools in the Ngqeleni area of Libode Mega District of the Eastern Cape, South Africa. The study was qualitative in nature; therefore interviews were used as the method of collecting data. Seven SMT members, four parents and four learners were, randomly selected from the two schools in the Ngqeleni area of Libode Mega District. The researcher randomly selected the participants then interviewed them. The researcher used a video recoder as an instrument to record the responses from the participants. To analyse data, the researcher transcribed the interview responses and interpreted them. The main findings of the study showed that the high failure rate was caused by the following factors: over-croweded classes, shortage of teaching and learnin~ materials, lack of parental involvement, teachers' low morale, poor learner discipline, teachers experiencing problems in implementing government policies, work-load and as such teaching becoming stressful. The researcher in his study therefore recommends that the Department of Education plans more workshops for schools to capacitate them. There should be provision for more classrooms and incentives for teachers. , Thesis (MMED) -- Faculty of Educational Sciences, 2019
- Full Text:
- Date Issued: 2014
An Interview with Ken Barris:
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144050 , vital:38306 , DOI: 10.4314/eia.v41i1.9
- Description: Ken Barris was born in Port Elizabeth and lives in Cape Town, where he works at the Cape Peninsula University of Technology. His writing includes two collections of poetry, a collection of short stories, and five novels, the most recent being What Kind of Child (2006) and Life Underwater (2012). His work has been translated into Turkish, Danish, German and Slovenian, and poetry and short fiction have appeared in various anthologies. More recently, he has turned to writing for academic journals. His research interests are postapartheid fiction and language education.
- Full Text:
- Date Issued: 2014
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144050 , vital:38306 , DOI: 10.4314/eia.v41i1.9
- Description: Ken Barris was born in Port Elizabeth and lives in Cape Town, where he works at the Cape Peninsula University of Technology. His writing includes two collections of poetry, a collection of short stories, and five novels, the most recent being What Kind of Child (2006) and Life Underwater (2012). His work has been translated into Turkish, Danish, German and Slovenian, and poetry and short fiction have appeared in various anthologies. More recently, he has turned to writing for academic journals. His research interests are postapartheid fiction and language education.
- Full Text:
- Date Issued: 2014
The incurious seeker: waiting, and the search for the stranger in the fiction of Samuel Beckett and JM Coetzee
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143971 , vital:38299 , https://mediatropes.com/index.php/Mediatropes/article/view/22380/18161
- Description: In J.M. Coetzee and the Novel: Writing and Politics after Beckett, Patrick Hayes argues that Coetzee, while influenced by Beckett’s prose style, assimilates it in such a way that his writing not only departs from the latter’s solipsism but also provides “an anti-foundational imagining of moral community” (71). While there is much merit to this argument, Hayes’s distinction between Beckett’s solipsism and Coetzee’s concern with community downplays the extent to which the human subject’s conception of herself depends on the differential process through which community establishes itself. In the first section of this paper I show that, already in Murphy, we find evidence in support of Ileana Marculescu’s argument that Beckett inscribes solipsism in his writing only to subvert it. Murphy’s attempts at solipsistic knowledge fail precisely because he has been estranged from himself by language and community. What appears to be solipsism is, in fact, a search for the self from which he has been divided by community. In Beckett’s writing, the self’s concern with its ability to know itself is always a concern with community.
- Full Text:
- Date Issued: 2014
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143971 , vital:38299 , https://mediatropes.com/index.php/Mediatropes/article/view/22380/18161
- Description: In J.M. Coetzee and the Novel: Writing and Politics after Beckett, Patrick Hayes argues that Coetzee, while influenced by Beckett’s prose style, assimilates it in such a way that his writing not only departs from the latter’s solipsism but also provides “an anti-foundational imagining of moral community” (71). While there is much merit to this argument, Hayes’s distinction between Beckett’s solipsism and Coetzee’s concern with community downplays the extent to which the human subject’s conception of herself depends on the differential process through which community establishes itself. In the first section of this paper I show that, already in Murphy, we find evidence in support of Ileana Marculescu’s argument that Beckett inscribes solipsism in his writing only to subvert it. Murphy’s attempts at solipsistic knowledge fail precisely because he has been estranged from himself by language and community. What appears to be solipsism is, in fact, a search for the self from which he has been divided by community. In Beckett’s writing, the self’s concern with its ability to know itself is always a concern with community.
- Full Text:
- Date Issued: 2014
Necrophiliac Narration and the Business of Friends: Damon Galgut’s The Good Doctor
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144159 , vital:38316 , DOI: 10.1080/17533171.2014.918406
- Description: Set in the period following South Africa’s first democratic elections, Damon Galgut’s The Good Doctor traces the friendship that develops between two doctors working at a rural hospital. While it does not deal overtly with the politics of the “new” South Africa, the novel’s treatment of friendship, which cuts across the distinction between the private and the public, reflects obliquely on the nature of the emerging democratic dispensation. In this paper, I explore the link that Galgut constructs between friendship and community, and argue that his portrayal of the former points to the possibility of a form of community that is premised on a “common strangeness.”
- Full Text:
- Date Issued: 2014
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144159 , vital:38316 , DOI: 10.1080/17533171.2014.918406
- Description: Set in the period following South Africa’s first democratic elections, Damon Galgut’s The Good Doctor traces the friendship that develops between two doctors working at a rural hospital. While it does not deal overtly with the politics of the “new” South Africa, the novel’s treatment of friendship, which cuts across the distinction between the private and the public, reflects obliquely on the nature of the emerging democratic dispensation. In this paper, I explore the link that Galgut constructs between friendship and community, and argue that his portrayal of the former points to the possibility of a form of community that is premised on a “common strangeness.”
- Full Text:
- Date Issued: 2014
Shame, divine cannibalism, and the spectacle of subaltern suffering in Ken Barris's What Kind of Child:
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144028 , vital:38304 , https://hdl.handle.net/10520/EJC171544
- Description: This essay examines the aesthetic and ethical dimensions of Ken Barns's portrayal of the life of a street child in What Kind of Child. Responses to literary representations of subaltem suffering are sharply divided. On the one hand, there is the commonsense view that such representations require one to imagine what the situation of other people may be like, and that, in doing so, one opens oneself to their experience of life. To the extent that representations of suffering inspire one to reflect on one's relations to others, they are salutary. On the other hand, though, such depictions, like poverty tourism, may be accused of providing a spectacle of distant suffering that one vicariously experiences from a position of privilege and then dircards.
- Full Text:
- Date Issued: 2014
- Authors: Marais, Mike
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144028 , vital:38304 , https://hdl.handle.net/10520/EJC171544
- Description: This essay examines the aesthetic and ethical dimensions of Ken Barns's portrayal of the life of a street child in What Kind of Child. Responses to literary representations of subaltem suffering are sharply divided. On the one hand, there is the commonsense view that such representations require one to imagine what the situation of other people may be like, and that, in doing so, one opens oneself to their experience of life. To the extent that representations of suffering inspire one to reflect on one's relations to others, they are salutary. On the other hand, though, such depictions, like poverty tourism, may be accused of providing a spectacle of distant suffering that one vicariously experiences from a position of privilege and then dircards.
- Full Text:
- Date Issued: 2014
Electrochemical behaviour of gold nanoparticles and Co tetraaminophthalocyanine on glassy carbon electrode
- Maringa, Audacity, Antunes, Edith M, Nyokong, Tebello
- Authors: Maringa, Audacity , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241573 , vital:50951 , xlink:href="https://doi.org/10.1016/j.electacta.2013.12.132"
- Description: We report on the electrodeposition of gold nanoparticles (AuNPs) onto the glassy carbon electrode (GCE) followed by polymerization of cobalt tetraamino phthalocyanine (CoPc(NH2)4) on top (represented as poly-CoPc(NH2)4-/AuNPs-GCE). The modified electrode where CoPc(NH2)4 is polymerized first followed by deposition of AuNPs is represented as AuNPs/poly-CoPc(NH2)4-GCE. In the absence of AuNPs, the electrode is represented as poly-CoPc(NH2)4-GCE or for AuNPs alone (AuNPs-GCE). The surface coverage was 1.5 × 10−9 mol cm−2 for AuNPs-GCE and 3.0 × 10−9 mol cm−2 for the rest of the modified electrodes. AuNPs/CoPc(NH2)4-GCE exhibited high electrocatalytic activity towards the oxidation of nitrite, with detection potential of 0.76 V. The catalytic rate constant of 3.96 × 107 cm3 mol−1 s−1 was obtained for nitrite oxidation.
- Full Text:
- Date Issued: 2014
- Authors: Maringa, Audacity , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241573 , vital:50951 , xlink:href="https://doi.org/10.1016/j.electacta.2013.12.132"
- Description: We report on the electrodeposition of gold nanoparticles (AuNPs) onto the glassy carbon electrode (GCE) followed by polymerization of cobalt tetraamino phthalocyanine (CoPc(NH2)4) on top (represented as poly-CoPc(NH2)4-/AuNPs-GCE). The modified electrode where CoPc(NH2)4 is polymerized first followed by deposition of AuNPs is represented as AuNPs/poly-CoPc(NH2)4-GCE. In the absence of AuNPs, the electrode is represented as poly-CoPc(NH2)4-GCE or for AuNPs alone (AuNPs-GCE). The surface coverage was 1.5 × 10−9 mol cm−2 for AuNPs-GCE and 3.0 × 10−9 mol cm−2 for the rest of the modified electrodes. AuNPs/CoPc(NH2)4-GCE exhibited high electrocatalytic activity towards the oxidation of nitrite, with detection potential of 0.76 V. The catalytic rate constant of 3.96 × 107 cm3 mol−1 s−1 was obtained for nitrite oxidation.
- Full Text:
- Date Issued: 2014
Behavior of palladium nanoparticles in the absence or presence of cobalt tetraaminophthalocyanine for the electrooxidation of hydrazine
- Maringa, Audacity, Nyokong, Tebello
- Authors: Maringa, Audacity , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189796 , vital:44932 , xlink:href="https://doi.org/10.1002/elan.201400028"
- Description: We report on the electrodeposition of palladium nanoparticles (PdNPs) on a glassy carbon electrode (GCE) and onto a poly-CoTAPc-GCE (CoTAPc=cobalt tetraamino phthalocyanine) surface. The electrodes are denoted as PdNPs-GCE and PdNPs/poly-CoTAPc-GCE, respectively. PdNPs/poly-CoTAPc-GCE showed the best activity for the oxidation of hydrazine at the lowest potential of −0.28 V and with the highest currents. The results were further supported by electrochemical impedance spectroscopy (EIS) which showed that there was less resistance to charge transfer for PdNPs/poly-CoTAPc-GCE compared to PdNPs-GCE. The catalytic rate constant for hydrazine oxidation was 6.12×108 cm3 mol−1 s−1 using PdNPs/poly-CoTAPc-GCE.
- Full Text:
- Date Issued: 2014
- Authors: Maringa, Audacity , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189796 , vital:44932 , xlink:href="https://doi.org/10.1002/elan.201400028"
- Description: We report on the electrodeposition of palladium nanoparticles (PdNPs) on a glassy carbon electrode (GCE) and onto a poly-CoTAPc-GCE (CoTAPc=cobalt tetraamino phthalocyanine) surface. The electrodes are denoted as PdNPs-GCE and PdNPs/poly-CoTAPc-GCE, respectively. PdNPs/poly-CoTAPc-GCE showed the best activity for the oxidation of hydrazine at the lowest potential of −0.28 V and with the highest currents. The results were further supported by electrochemical impedance spectroscopy (EIS) which showed that there was less resistance to charge transfer for PdNPs/poly-CoTAPc-GCE compared to PdNPs-GCE. The catalytic rate constant for hydrazine oxidation was 6.12×108 cm3 mol−1 s−1 using PdNPs/poly-CoTAPc-GCE.
- Full Text:
- Date Issued: 2014
Characterization of electrodes modified by one pot or step by step electro-click reaction and axial ligation of iron tetracarboxyphthalocyanine
- Maringa, Audacity, Mashazi, Philani N, Nyokong, Tebello
- Authors: Maringa, Audacity , Mashazi, Philani N , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193892 , vital:45403 , xlink:href="https://doi.org/10.1016/j.electacta.2014.09.011"
- Description: The modification of the glassy carbon electrode (GCE) was carried out using two methods. The first method is simultaneous electropolymerization and electro-click followed by immersion into a solution of dimethyl formamide (DMF) containing FeTCPc. The second method is step by step whereby electropolymerization is carried out first followed by electro-click and then immersion into a DMF solution containing FeTCPc. From the electrochemical characterization, it was observed that the second route (step by step method) was the best as indicated by the ferricyanide studies (cyclic voltammetry and scanning electrochemical microscopy). In the electrooxidation of hydrazine, we obtained a potential of 0.26 V. Of interest were the detection limit of 6.4 μM and the catalytic rate constant of 2.1 × 109 cm3 mol−1 s−1. This shows that the sensor can be used for the electrooxidation of hydrazine.
- Full Text:
- Date Issued: 2014
- Authors: Maringa, Audacity , Mashazi, Philani N , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193892 , vital:45403 , xlink:href="https://doi.org/10.1016/j.electacta.2014.09.011"
- Description: The modification of the glassy carbon electrode (GCE) was carried out using two methods. The first method is simultaneous electropolymerization and electro-click followed by immersion into a solution of dimethyl formamide (DMF) containing FeTCPc. The second method is step by step whereby electropolymerization is carried out first followed by electro-click and then immersion into a DMF solution containing FeTCPc. From the electrochemical characterization, it was observed that the second route (step by step method) was the best as indicated by the ferricyanide studies (cyclic voltammetry and scanning electrochemical microscopy). In the electrooxidation of hydrazine, we obtained a potential of 0.26 V. Of interest were the detection limit of 6.4 μM and the catalytic rate constant of 2.1 × 109 cm3 mol−1 s−1. This shows that the sensor can be used for the electrooxidation of hydrazine.
- Full Text:
- Date Issued: 2014