Iodine-Doped Cobalt Phthalocyanine Supported on Multiwalled Carbon Nanotubes for Electrocatalysis of Oxygen Reduction Reaction
- Nyoni, Stephen, Mashazi, Philani N, Nyokong, Tebello
- Authors: Nyoni, Stephen , Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189434 , vital:44846 , xlink:href="https://doi.org/10.1002/elan.201400499"
- Description: 4-(4,6-Diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II) (CoPyPc) was iodine doped, and its electrocatalytic properties explored. Physical characterization techniques such as UV-vis, X-ray photoelectron, electron paramagnetic resonance and infra-red spectroscopy were used. Cyclic voltammetry, electrochemical impedance spectroscopy and rotating disk electrode were used for electrochemical characterization of electrodes modified with the prepared phthalocyanine and its nanocomposites. The electrocatalytic effect of a new iodine-doped cobalt phthalocyanine derivative supported on multiwalled carbon nanotubes was then investigated towards oxygen reduction reaction. The electrocatalytic activity of the iodine-doped cobalt phthalocyanine was found to be superior in terms of current over the undoped phthalocyanine nanocomposite.
- Full Text:
- Date Issued: 2015
- Authors: Nyoni, Stephen , Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189434 , vital:44846 , xlink:href="https://doi.org/10.1002/elan.201400499"
- Description: 4-(4,6-Diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II) (CoPyPc) was iodine doped, and its electrocatalytic properties explored. Physical characterization techniques such as UV-vis, X-ray photoelectron, electron paramagnetic resonance and infra-red spectroscopy were used. Cyclic voltammetry, electrochemical impedance spectroscopy and rotating disk electrode were used for electrochemical characterization of electrodes modified with the prepared phthalocyanine and its nanocomposites. The electrocatalytic effect of a new iodine-doped cobalt phthalocyanine derivative supported on multiwalled carbon nanotubes was then investigated towards oxygen reduction reaction. The electrocatalytic activity of the iodine-doped cobalt phthalocyanine was found to be superior in terms of current over the undoped phthalocyanine nanocomposite.
- Full Text:
- Date Issued: 2015
Comparative electrocatalytic studies of nanocomposites of mixed and covalently linked multiwalled carbon nanotubes and 4-(4, 6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt (II)
- Nyoni, Stephen, Nyokong, Tebello
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
- Full Text:
- Date Issued: 2015
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189285 , vital:44834 , xlink:href="https://doi.org/10.1016/j.poly.2015.05.038"
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite.
- Full Text:
- Date Issued: 2015
Comparative electrocatalytic studies of nanocomposites of mixed and covalently linked multiwalled carbon nanotubes and 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II)
- Nyoni, Stephen, Nyokong, Tebello
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7285 , http://hdl.handle.net/10962/d1020332
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards l-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2015.05.038
- Full Text: false
- Authors: Nyoni, Stephen , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7285 , http://hdl.handle.net/10962/d1020332
- Description: Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards l-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2015.05.038
- Full Text: false
Iodine-Doped Cobalt Phthalocyanine Supported on Multiwalled Carbon Nanotubes for Electrocatalysis of Oxygen Reduction Reaction
- Nyoni, Stephen, Mashazi, Philani N, Nyokong, Tebello
- Authors: Nyoni, Stephen , Mashazi, Philani N , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7242 , http://hdl.handle.net/10962/d1020246
- Description: 4-(4,6-Diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II) (CoPyPc) was iodine doped, and its electrocatalytic properties explored. Physical characterization techniques such as UV-vis, X-ray photoelectron, electron paramagnetic resonance and infra-red spectroscopy were used. Cyclic voltammetry, electrochemical impedance spectroscopy and rotating disk electrode were used for electrochemical characterization of electrodes modified with the prepared phthalocyanine and its nanocomposites. The electrocatalytic effect of a new iodine-doped cobalt phthalocyanine derivative supported on multiwalled carbon nanotubes was then investigated towards oxygen reduction reaction. The electrocatalytic activity of the iodine-doped cobalt phthalocyanine was found to be superior in terms of current over the undoped phthalocyanine nanocomposite. , Original publication is available at http://dx.doi.org/10.1002/elan.201400499
- Full Text: false
- Authors: Nyoni, Stephen , Mashazi, Philani N , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7242 , http://hdl.handle.net/10962/d1020246
- Description: 4-(4,6-Diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II) (CoPyPc) was iodine doped, and its electrocatalytic properties explored. Physical characterization techniques such as UV-vis, X-ray photoelectron, electron paramagnetic resonance and infra-red spectroscopy were used. Cyclic voltammetry, electrochemical impedance spectroscopy and rotating disk electrode were used for electrochemical characterization of electrodes modified with the prepared phthalocyanine and its nanocomposites. The electrocatalytic effect of a new iodine-doped cobalt phthalocyanine derivative supported on multiwalled carbon nanotubes was then investigated towards oxygen reduction reaction. The electrocatalytic activity of the iodine-doped cobalt phthalocyanine was found to be superior in terms of current over the undoped phthalocyanine nanocomposite. , Original publication is available at http://dx.doi.org/10.1002/elan.201400499
- Full Text: false
Electrode modification using nanocomposites of electropolymerised cobalt phthalocyanines supported on multiwalled carbon nanotubes
- Nyoni, Stephen, Mashazi, Philani N, Nyokong, Tebello
- Authors: Nyoni, Stephen , Mashazi, Philani N , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7293 , http://hdl.handle.net/10962/d1020356
- Description: A polymer of tetra(4)-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II) (CoPyPc) has been deposited over a multiwalled carbon nanotube (MWCNT) platform and its electrocatalytic properties investigated side by side with polymerized cobalt tetraamino phthalocyanine (CoTAPc). X-ray photoelectron spectroscopy, scanning electron microscopy and cyclic voltammetry studies were used for characterization of the prepared polymers of cobalt phthalocyanine derivatives and their nanocomposites. l-Cysteine was used as a test analyte for the electrocatalytic activity of the nanocomposites of polymerized cobalt phthalocyanines and multiwalled carbon nanotubes. The electrocatalytic activity of both polymerized cobalt phthalocyanines was found to be superior when polymerization was done on top of MWCNTs compared to bare glassy carbon electrode. A higher sensitivity for l-cysteine detection was obtained on CoTAPc compared to CoPyPc. , Original publication is available at http://dx.doi.org/10.1007/s10008-015-2985-6
- Full Text: false
- Authors: Nyoni, Stephen , Mashazi, Philani N , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7293 , http://hdl.handle.net/10962/d1020356
- Description: A polymer of tetra(4)-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II) (CoPyPc) has been deposited over a multiwalled carbon nanotube (MWCNT) platform and its electrocatalytic properties investigated side by side with polymerized cobalt tetraamino phthalocyanine (CoTAPc). X-ray photoelectron spectroscopy, scanning electron microscopy and cyclic voltammetry studies were used for characterization of the prepared polymers of cobalt phthalocyanine derivatives and their nanocomposites. l-Cysteine was used as a test analyte for the electrocatalytic activity of the nanocomposites of polymerized cobalt phthalocyanines and multiwalled carbon nanotubes. The electrocatalytic activity of both polymerized cobalt phthalocyanines was found to be superior when polymerization was done on top of MWCNTs compared to bare glassy carbon electrode. A higher sensitivity for l-cysteine detection was obtained on CoTAPc compared to CoPyPc. , Original publication is available at http://dx.doi.org/10.1007/s10008-015-2985-6
- Full Text: false
The development of biological tools to aid in the genetic investigation of the black (Diceros bicornis) and white (Ceratotherium simum) rhinoceros mitochondrial genomes
- Authors: Parsons, Michelle
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/56059 , vital:26769
- Description: The black (Diceros bicornis) and white (Ceratotherium simum) rhinoceros are found in South Africa. A decline in the populations of these species has resulted due to human activities such as habitat fragmentation and poaching. This has contributed to the loss of genetic diversity amongst the black and white rhinoceros. Conservation and anti-poaching efforts are needed to help maintain genetic diversity. These efforts could be improved through the development of non-invasive techniques to examine DNA from threatened animals. The aim of this research was to develop a molecular technique which would allow for the identification of the black and white rhinoceros and to develop a molecular technique which would allow for intraspecies genetic variation to be examined. DNA extractions were performed on matched faecal and tissue samples that were collected from two regions in South Africa. Polymerase chain reaction (PCR) primer sets were designed to investigate several regions of the rhinoceros mitochondrial genome. PCR optimisation was completed for the target regions. Sequencing was conducted on all final PCR products. The cytochrome c oxidase subunit 1 (COIi) gene allowed for the rhinoceros family to be identified. This region was digested with the HindIII restriction enzyme, which allowed for the specific identification of either the black or white rhinoceros. A subsequent region of the cytochrome c oxidase subunit 1 (COIii) as well as the D-loop, hypervariable regions (HV1 and HV2), cytochrome b (cytb) and 16s rRNA regions were investigated. These regions displayed potential for establishing geographic origin for black rhinoceros samples, whereas the D-loop and HV2 show potential for the white rhinoceros. The white rhinoceros displayed sequence variation in the HV2 and cytb region, while variation was observed in the COIi and HV1 for the black rhinoceros. All investigated target regions allowed for the rhinoceros family to be identified. The COI (COIi and COIii), HV2 and cytb regions allowed for the subspecies of rhinoceros to be identified, however the D-loop was not able to identify the white rhinoceros species. The 16s rRNA and HV1 regions allowed for the correct subspecies of rhinoceros to be identified, however as the primers were only compatible for the black rhinoceros therefore a subsequent investigation is required for the white rhinoceros. The establishment of this novel PCR based technique to identify white and black rhinoceros will allow for efficient species identification in wildlife forensic cases. A biological method was established to study intraspecies variation for the white and black rhinoceros; however the investigated target regions did not yield sufficient genetic variation. The core techniques developed in this study will be valuable for future studies that wish to investigate genetic variation in mammal species.
- Full Text:
- Date Issued: 2015
- Authors: Parsons, Michelle
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/56059 , vital:26769
- Description: The black (Diceros bicornis) and white (Ceratotherium simum) rhinoceros are found in South Africa. A decline in the populations of these species has resulted due to human activities such as habitat fragmentation and poaching. This has contributed to the loss of genetic diversity amongst the black and white rhinoceros. Conservation and anti-poaching efforts are needed to help maintain genetic diversity. These efforts could be improved through the development of non-invasive techniques to examine DNA from threatened animals. The aim of this research was to develop a molecular technique which would allow for the identification of the black and white rhinoceros and to develop a molecular technique which would allow for intraspecies genetic variation to be examined. DNA extractions were performed on matched faecal and tissue samples that were collected from two regions in South Africa. Polymerase chain reaction (PCR) primer sets were designed to investigate several regions of the rhinoceros mitochondrial genome. PCR optimisation was completed for the target regions. Sequencing was conducted on all final PCR products. The cytochrome c oxidase subunit 1 (COIi) gene allowed for the rhinoceros family to be identified. This region was digested with the HindIII restriction enzyme, which allowed for the specific identification of either the black or white rhinoceros. A subsequent region of the cytochrome c oxidase subunit 1 (COIii) as well as the D-loop, hypervariable regions (HV1 and HV2), cytochrome b (cytb) and 16s rRNA regions were investigated. These regions displayed potential for establishing geographic origin for black rhinoceros samples, whereas the D-loop and HV2 show potential for the white rhinoceros. The white rhinoceros displayed sequence variation in the HV2 and cytb region, while variation was observed in the COIi and HV1 for the black rhinoceros. All investigated target regions allowed for the rhinoceros family to be identified. The COI (COIi and COIii), HV2 and cytb regions allowed for the subspecies of rhinoceros to be identified, however the D-loop was not able to identify the white rhinoceros species. The 16s rRNA and HV1 regions allowed for the correct subspecies of rhinoceros to be identified, however as the primers were only compatible for the black rhinoceros therefore a subsequent investigation is required for the white rhinoceros. The establishment of this novel PCR based technique to identify white and black rhinoceros will allow for efficient species identification in wildlife forensic cases. A biological method was established to study intraspecies variation for the white and black rhinoceros; however the investigated target regions did not yield sufficient genetic variation. The core techniques developed in this study will be valuable for future studies that wish to investigate genetic variation in mammal species.
- Full Text:
- Date Issued: 2015
Rhodes University Research Report 2015
- Rhodes University, Gillitt, Tarryn, Goba, Busi, Macgregor, Jill, Roberts, Jaine, Dore, Sally
- Authors: Rhodes University , Gillitt, Tarryn , Goba, Busi , Macgregor, Jill , Roberts, Jaine , Dore, Sally
- Date: 2015
- Language: English
- Type: Text
- Identifier: http://hdl.handle.net/10962/59298 , vital:27546
- Description: From Foreword by Dr Sizwe Mabizela: A further feature of research at Rhodes University has long been international collaborations, many of them responsible for raising the international competitiveness and voice of scholarship involving Rhodes academics and students. In March 2015, Rhodes University became a founder member of the African Research Universities’ Alliance (ARUA), launched at the African Higher Education Summit in Senegal. Leading universities with strong programmes of research and Postgraduate training formed the network of 16 institutions, which aim to bring together intersecting and complementary strengths in the interest of building critical mass in the key development priorities of the African continent. , A publication of the Rhodes University Research Office, compiled and edited by Tarryn Gillitt, Busi Goba, Patricia Jacob, Jill Macgregor and Jaine Roberts. Design & Layout: Sally Dore.
- Full Text:
- Date Issued: 2015
- Authors: Rhodes University , Gillitt, Tarryn , Goba, Busi , Macgregor, Jill , Roberts, Jaine , Dore, Sally
- Date: 2015
- Language: English
- Type: Text
- Identifier: http://hdl.handle.net/10962/59298 , vital:27546
- Description: From Foreword by Dr Sizwe Mabizela: A further feature of research at Rhodes University has long been international collaborations, many of them responsible for raising the international competitiveness and voice of scholarship involving Rhodes academics and students. In March 2015, Rhodes University became a founder member of the African Research Universities’ Alliance (ARUA), launched at the African Higher Education Summit in Senegal. Leading universities with strong programmes of research and Postgraduate training formed the network of 16 institutions, which aim to bring together intersecting and complementary strengths in the interest of building critical mass in the key development priorities of the African continent. , A publication of the Rhodes University Research Office, compiled and edited by Tarryn Gillitt, Busi Goba, Patricia Jacob, Jill Macgregor and Jaine Roberts. Design & Layout: Sally Dore.
- Full Text:
- Date Issued: 2015
Effects of natural antioxidants and thermal treatment on quality of meat from Bonsmara and non-descripts cattle
- Authors: Falowo, Andrew Bamidele
- Date: 2015
- Subjects: Meat -- Preservation Antioxidants Meat -- Microbiology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2589 , vital:27906
- Description: The broad objective of this study was to determine the effects of natural antioxidants and thermal treatment on quality of meat from Bonsmara and non-descript cattle. A survey was conducted among 222 consumers in Alice (Fort Hare University community), Eastern Cape Province to determine the level of their awareness on application of antioxidants as preservatives in meat and meat products during storage. Representative samples of Muscularis longissimuss thoracis et lumborum and liver were collected from each carcass of Bonsmara (n=40) and non-descript (n=40) cattle reared on natural pasture to determine the effect of natural antioxidants and thermal treatment on their quality. The results from the survey revealed that 51.35 percent of the respondents had not heard about the use of antioxidant as preservatives in meat products. However, among the remaining respondents (48.65 percent) that were aware of antioxidant and its use as preservative, about 19 percent knew of natural antioxidants, 35 percent synthetic antioxidants while 46 percent had knowledge of both. The results further revealed that the majority of the respondents (82 percent) that had knowledge of natural antioxidants were concerned about the use of synthetic antioxidants in meat and meat products due to their health consequences. The in vitro antioxidant and antibacterial analyses of Bidens pilosa and Moringa oleifera leaf extracts revealed that they contain rich bioactive compounds. Furthermore, the addition of leaf extracts from Moringa oleifera (ML, 0.05 and 0.1 percent w/w) and Biden pilosa (BP, 0.05 and 0.1 percent w/w) to ground raw beef as a natural antioxidant were found to improve the physicochemical, oxidative stability and microbiological qualities of meat compared to the control (meat without extract) and BHT treatment (0.02 percent w/w) during 6 days storage at 40 C. Cattle breed did not have much effect on colour parameters. However, the overall pH of ground beef treated with extracts showed lower values than control and BHT treated beef. Also, ground beef samples containing extracts exhibited (P < 0.05) better colour stability, especially higher redness (a* values), than the control. The formation of TBARS in beef samples treated with extracts was significantly (P < 0.05) lower than the control and BHT treatment. The antibacterial assay of the extracts revealed an appreciable broad spectrum activity against the tested bacteria and microbial counts in ground beef samples compared to control and BHT group. Ground beef treated with plant extracts exhibited lower microbial and lactic acid bacterial counts (P < 0.05) at day 0 and 3 than control samples. Moreover, it was observed that application of sous vides thermal method did not significantly affect the fatty acids and mineral loss in beef and liver across the treatments. However, the total concentration of MUFA was lower in raw liver (20.11±2.38 - 21.08±1.23 percent) than in beef (40.22±1.90 - 42.53±1.29 percent), while total PUFA content were higher in liver (30.73±2.60 - 31.11±1.19 percent) than in beef samples (10.13±3.36 - 11.02±2.74 percent) (p < 0.05). The results also revealed that liver samples from Bonsmara and non-descript cattle had a higher percentage of intramuscular fat content of 4.67 ± 0.53 percent and 4.44 ± 0.53 percent respectively, and fat free dry matter of 27.51 ± 1.05 percent and 25.73 ± 1.05 percent, respectively, than the beef samples (p < 0.05). The concentrations of Mg (52.80±0.22 - 53.70±0.02mg/100g) and Zn (8.90±0.15 - 19.60±0.15mg/100g) were higher in beef than liver samples. The level of Ca (17.00±0.17 - 17.50 ± 0.17mg/100g) in liver was higher than that of beef samples. It was concluded that most consumers preferred the use of natural antioxidants in meat products than synthetic antioxidants due to their health risk. The effectiveness of M. oleifera and B. pilosa leaf extracts on meat quality also revealed that these plants are promising candidates as natural preservatives and their application should be considered in the meat industry. Lastly, findings from this study showed that application of the sous vide technique could protect meat products from nutritional loss during thermal treatment.
- Full Text:
- Date Issued: 2015
- Authors: Falowo, Andrew Bamidele
- Date: 2015
- Subjects: Meat -- Preservation Antioxidants Meat -- Microbiology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2589 , vital:27906
- Description: The broad objective of this study was to determine the effects of natural antioxidants and thermal treatment on quality of meat from Bonsmara and non-descript cattle. A survey was conducted among 222 consumers in Alice (Fort Hare University community), Eastern Cape Province to determine the level of their awareness on application of antioxidants as preservatives in meat and meat products during storage. Representative samples of Muscularis longissimuss thoracis et lumborum and liver were collected from each carcass of Bonsmara (n=40) and non-descript (n=40) cattle reared on natural pasture to determine the effect of natural antioxidants and thermal treatment on their quality. The results from the survey revealed that 51.35 percent of the respondents had not heard about the use of antioxidant as preservatives in meat products. However, among the remaining respondents (48.65 percent) that were aware of antioxidant and its use as preservative, about 19 percent knew of natural antioxidants, 35 percent synthetic antioxidants while 46 percent had knowledge of both. The results further revealed that the majority of the respondents (82 percent) that had knowledge of natural antioxidants were concerned about the use of synthetic antioxidants in meat and meat products due to their health consequences. The in vitro antioxidant and antibacterial analyses of Bidens pilosa and Moringa oleifera leaf extracts revealed that they contain rich bioactive compounds. Furthermore, the addition of leaf extracts from Moringa oleifera (ML, 0.05 and 0.1 percent w/w) and Biden pilosa (BP, 0.05 and 0.1 percent w/w) to ground raw beef as a natural antioxidant were found to improve the physicochemical, oxidative stability and microbiological qualities of meat compared to the control (meat without extract) and BHT treatment (0.02 percent w/w) during 6 days storage at 40 C. Cattle breed did not have much effect on colour parameters. However, the overall pH of ground beef treated with extracts showed lower values than control and BHT treated beef. Also, ground beef samples containing extracts exhibited (P < 0.05) better colour stability, especially higher redness (a* values), than the control. The formation of TBARS in beef samples treated with extracts was significantly (P < 0.05) lower than the control and BHT treatment. The antibacterial assay of the extracts revealed an appreciable broad spectrum activity against the tested bacteria and microbial counts in ground beef samples compared to control and BHT group. Ground beef treated with plant extracts exhibited lower microbial and lactic acid bacterial counts (P < 0.05) at day 0 and 3 than control samples. Moreover, it was observed that application of sous vides thermal method did not significantly affect the fatty acids and mineral loss in beef and liver across the treatments. However, the total concentration of MUFA was lower in raw liver (20.11±2.38 - 21.08±1.23 percent) than in beef (40.22±1.90 - 42.53±1.29 percent), while total PUFA content were higher in liver (30.73±2.60 - 31.11±1.19 percent) than in beef samples (10.13±3.36 - 11.02±2.74 percent) (p < 0.05). The results also revealed that liver samples from Bonsmara and non-descript cattle had a higher percentage of intramuscular fat content of 4.67 ± 0.53 percent and 4.44 ± 0.53 percent respectively, and fat free dry matter of 27.51 ± 1.05 percent and 25.73 ± 1.05 percent, respectively, than the beef samples (p < 0.05). The concentrations of Mg (52.80±0.22 - 53.70±0.02mg/100g) and Zn (8.90±0.15 - 19.60±0.15mg/100g) were higher in beef than liver samples. The level of Ca (17.00±0.17 - 17.50 ± 0.17mg/100g) in liver was higher than that of beef samples. It was concluded that most consumers preferred the use of natural antioxidants in meat products than synthetic antioxidants due to their health risk. The effectiveness of M. oleifera and B. pilosa leaf extracts on meat quality also revealed that these plants are promising candidates as natural preservatives and their application should be considered in the meat industry. Lastly, findings from this study showed that application of the sous vide technique could protect meat products from nutritional loss during thermal treatment.
- Full Text:
- Date Issued: 2015
The synthesis and analysis of (2R,3R)-1,1,4,4- tetraphenylbutane-1,2,3,4-tetraol (tetrol) and derivatives, and a study of their host potential
- Authors: Weitz, Selwyn Herbert
- Date: 2015
- Subjects: Chemistry, Organic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3735 , vital:20459
- Description: This investigation focussed on the inclusion and resolution ability of (2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL), studies on the stoichiometry of its derivatives and the formation of inclusion compounds for single crystal analysis. The guest compounds that featured in the main study were cyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone and 4-methylcyclohexanone. It was found that 3- and 4-methylcyclohexanone were trapped in their energetically unfavourable axial conformations in the inclusion crystal. Resolution experiments proved that (2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol can be used as a resolving agent for 2- and 3-methylcyclohexanone, with ee values of 13% and 22%, respectively (according to the method of Hiemstra), in favour of the R-enantiomer. Single crystal X-ray diffraction (SCXRD) studies, however, showed that 2-methylcyclohexanone was resolved with an ee of 30% in R. An ee of 56% in R was obtained for 3-methylcyclohexanone. Enantiomer enrichment of 2-methylcyclohexanone was achieved in basic medium (ee of 18% according to the method of Hiemstra) and showed that by using the host in either half or double the molar ratio of the guest, a higher ee was obtained than for a 1:1 ratio. The following TETROL derivatives were also synthesized and their stoichiometries with various guest compounds were determined: (2R,3R)-1,1,4,4-tetra(naphthalen-1-yl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(naphthalen-2-yl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(p-anisyl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(p-tolyl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(m-tolyl)butane-1,2,3,4-tetraol and; (2R,3R)-1,1,4,4-tetra(o-tolyl)butane-1,2,3,4-tetraol.
- Full Text:
- Date Issued: 2015
- Authors: Weitz, Selwyn Herbert
- Date: 2015
- Subjects: Chemistry, Organic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3735 , vital:20459
- Description: This investigation focussed on the inclusion and resolution ability of (2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL), studies on the stoichiometry of its derivatives and the formation of inclusion compounds for single crystal analysis. The guest compounds that featured in the main study were cyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone and 4-methylcyclohexanone. It was found that 3- and 4-methylcyclohexanone were trapped in their energetically unfavourable axial conformations in the inclusion crystal. Resolution experiments proved that (2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol can be used as a resolving agent for 2- and 3-methylcyclohexanone, with ee values of 13% and 22%, respectively (according to the method of Hiemstra), in favour of the R-enantiomer. Single crystal X-ray diffraction (SCXRD) studies, however, showed that 2-methylcyclohexanone was resolved with an ee of 30% in R. An ee of 56% in R was obtained for 3-methylcyclohexanone. Enantiomer enrichment of 2-methylcyclohexanone was achieved in basic medium (ee of 18% according to the method of Hiemstra) and showed that by using the host in either half or double the molar ratio of the guest, a higher ee was obtained than for a 1:1 ratio. The following TETROL derivatives were also synthesized and their stoichiometries with various guest compounds were determined: (2R,3R)-1,1,4,4-tetra(naphthalen-1-yl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(naphthalen-2-yl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(p-anisyl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(p-tolyl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(m-tolyl)butane-1,2,3,4-tetraol and; (2R,3R)-1,1,4,4-tetra(o-tolyl)butane-1,2,3,4-tetraol.
- Full Text:
- Date Issued: 2015
Chemical constituents and biological studies of Tagetes minuta L. and Rauvolfia caffra Sond
- Authors: Mlala, Sithenkosi
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc (Organic Chemistry)
- Identifier: vital:11358 , http://hdl.handle.net/10353/d1021325
- Description: Consequently, specific parts or the whole plant can be used for various treatments. The aim of this study was to extract, isolate and characterize the biologically active volatile and non-volatile compounds from Tagetes minuta and Rauvolfia caffra respectively. Tagetes minuta plant was considered for extraction of essential oils using hydrodistillation method. Cis-β-ocimene (38.03%), caryophyllene oxide (18.04%), alloocimene (25.35 %), isopropyl tetradecanoate (17.02 %), cis-ocimene (38.14%) and trans-β-ocimene (37.03%) were the major components of essential oil analyzed from fresh stem, dried stem, fresh leaf, dried leaf, fresh flower and dried flower respectively. The volatile compounds were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography (GC). Essential oil of dried stem leaf and flower parts of T. minuta exhibit antioxidant activity as demonstrated by the DPPH and FRAP bioassays. Crude extracts were extracted from R. caffra stem bark using sequence of solvents namely n-hexane, dichloromethane, ethyl acetate, methanol and ethanol. A white powder, a β-sitosterol (non-volatile compound) was isolated by column chromatography from ethyl acetate fractions of R. caffra stem bark and identified on various spectroscopic techniques such as FTIR and (1D and 2D) NMR. Melting point was also determined to be a sharp 129-130 ºC. DCM, EA, MetOH and EtOH fractions as well as β-Sitosterol (compound SM/01), showed antioxidant activity when tested on DPPH, FRAP, total phenolic and flavonoid bioassays. This antioxidant activity might be due to the presence of hydroxyl groups in the compound and crude fractions. On the other hand, T. minuta’s essential oil showed high antioxidant activity when evaluated on the DPPH and FRAP bioassays, which can be attributed to the presence of oxygenated monoterpenes and sesquiterpenes known to act as free radical scavenging and reducing agents. The use of R. caffra stem bark extracts against hypertension and other diseases by traditional healers could be attributed to the presence of phytochemicals (polyphenols and flavonoids) with known health benefits. Thus, it is recommended that the plant should be exploited further using modern techniques involving separation and purification of compounds that can be used for drug formulation. This study supports the use of T. minuta and R. caffra as the potential natural antioxidant source to manage various diseases including hypertension.
- Full Text:
- Date Issued: 2015
- Authors: Mlala, Sithenkosi
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc (Organic Chemistry)
- Identifier: vital:11358 , http://hdl.handle.net/10353/d1021325
- Description: Consequently, specific parts or the whole plant can be used for various treatments. The aim of this study was to extract, isolate and characterize the biologically active volatile and non-volatile compounds from Tagetes minuta and Rauvolfia caffra respectively. Tagetes minuta plant was considered for extraction of essential oils using hydrodistillation method. Cis-β-ocimene (38.03%), caryophyllene oxide (18.04%), alloocimene (25.35 %), isopropyl tetradecanoate (17.02 %), cis-ocimene (38.14%) and trans-β-ocimene (37.03%) were the major components of essential oil analyzed from fresh stem, dried stem, fresh leaf, dried leaf, fresh flower and dried flower respectively. The volatile compounds were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography (GC). Essential oil of dried stem leaf and flower parts of T. minuta exhibit antioxidant activity as demonstrated by the DPPH and FRAP bioassays. Crude extracts were extracted from R. caffra stem bark using sequence of solvents namely n-hexane, dichloromethane, ethyl acetate, methanol and ethanol. A white powder, a β-sitosterol (non-volatile compound) was isolated by column chromatography from ethyl acetate fractions of R. caffra stem bark and identified on various spectroscopic techniques such as FTIR and (1D and 2D) NMR. Melting point was also determined to be a sharp 129-130 ºC. DCM, EA, MetOH and EtOH fractions as well as β-Sitosterol (compound SM/01), showed antioxidant activity when tested on DPPH, FRAP, total phenolic and flavonoid bioassays. This antioxidant activity might be due to the presence of hydroxyl groups in the compound and crude fractions. On the other hand, T. minuta’s essential oil showed high antioxidant activity when evaluated on the DPPH and FRAP bioassays, which can be attributed to the presence of oxygenated monoterpenes and sesquiterpenes known to act as free radical scavenging and reducing agents. The use of R. caffra stem bark extracts against hypertension and other diseases by traditional healers could be attributed to the presence of phytochemicals (polyphenols and flavonoids) with known health benefits. Thus, it is recommended that the plant should be exploited further using modern techniques involving separation and purification of compounds that can be used for drug formulation. This study supports the use of T. minuta and R. caffra as the potential natural antioxidant source to manage various diseases including hypertension.
- Full Text:
- Date Issued: 2015
The impact of unemployment on grade R learners in Stephen Mazungula primary school in the Nelson Mandela Metropole
- Authors: Mbengashe, Nosipho Theodora
- Date: 2015
- Subjects: Children with social disabilities -- Education Poverty
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/12560 , vital:27094
- Description: The biggest problems facing South Africa is high rate of poverty. There are many reasons behind the high levels of poverty, and one of them is unemployment rate. Poverty is felt by particular groups, especially pro poor. Researchers brought to our attention that there is a link between poverty, children health and their school performance. According to the Millennium development goals, eradication of poverty, achieve primary education, empower women, and reduce mortality rate link together. For these goals to be achieved, full responsibility of women as life carriers should be taken into consideration as role players in upbringing children lives. Women health should be catered for better health as they are linked to the unborn and also born babies. In order to learn effectively and successfully one must be in good health. Children raised in poverty are subject to health problems, and at times suffer grave consequences because of some nutrients deficit in their bodies. The descriptive study investigated the impact of unemployment on Grade R learners in Stephen Mazungula Primary School in Nelson Mandela Bay Metropole. To understand the problems faced by learners and make recommendations. The study made use of sources like documents, government laws and policies, books, journals, newspaper articles and internet to promote the best interest of a child.
- Full Text:
- Date Issued: 2015
- Authors: Mbengashe, Nosipho Theodora
- Date: 2015
- Subjects: Children with social disabilities -- Education Poverty
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/12560 , vital:27094
- Description: The biggest problems facing South Africa is high rate of poverty. There are many reasons behind the high levels of poverty, and one of them is unemployment rate. Poverty is felt by particular groups, especially pro poor. Researchers brought to our attention that there is a link between poverty, children health and their school performance. According to the Millennium development goals, eradication of poverty, achieve primary education, empower women, and reduce mortality rate link together. For these goals to be achieved, full responsibility of women as life carriers should be taken into consideration as role players in upbringing children lives. Women health should be catered for better health as they are linked to the unborn and also born babies. In order to learn effectively and successfully one must be in good health. Children raised in poverty are subject to health problems, and at times suffer grave consequences because of some nutrients deficit in their bodies. The descriptive study investigated the impact of unemployment on Grade R learners in Stephen Mazungula Primary School in Nelson Mandela Bay Metropole. To understand the problems faced by learners and make recommendations. The study made use of sources like documents, government laws and policies, books, journals, newspaper articles and internet to promote the best interest of a child.
- Full Text:
- Date Issued: 2015
Invariant control systems and sub-Riemannian structures on lie groups: equivalence and isometries
- Authors: Biggs, Rory
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64815 , vital:28607
- Description: In this thesis we consider invariant optimal control problems and invariant sub-Riemannian structures on Lie groups. Primarily, we are concerned with the equivalence and classification of problems (resp. structures). In the first chapter, both the class of invariant optimal control problems and the class of invariant sub-Riemannian structures are organised as categories. The latter category is shown to be functorially equivalent to a subcategory of the former category. Via the Pontryagin Maximum Principle, we associate to each invariant optimal control problem (resp. invariant sub-Riemannian structure) a quadratic Hamilton-Poisson system on the associated Lie-Poisson space. These Hamiltonian systems are also organised as a category and hence the Pontryagin lift is realised as a contravariant functor. Basic properties of these categories are investigated. The rest of this thesis is concerned with the classification (and investigation) of certain subclasses of structures and systems. In the second chapter, the homogeneous positive semidefinite quadratic Hamilton-Poisson systems on three-dimensional Lie-Poisson spaces are classified up to compatibility with a linear isomorphism; a list of 23 normal forms is exhibited. In the third chapter, we classify the invariant sub-Riemannian structures in three dimensions and calculate the isometry group for each normal form. By comparing our results with known results, we show that most isometries (in three dimensions) are in fact the composition of a left translation and a Lie group isomorphism. In the fourth and last chapter of this thesis, we classify the sub-Riemannian and Riemannian structures on the (2n + 1)-dimensional Heisenberg groups. Furthermore, we find the isometry group and geodesics of each normal form.
- Full Text:
- Date Issued: 2015
- Authors: Biggs, Rory
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64815 , vital:28607
- Description: In this thesis we consider invariant optimal control problems and invariant sub-Riemannian structures on Lie groups. Primarily, we are concerned with the equivalence and classification of problems (resp. structures). In the first chapter, both the class of invariant optimal control problems and the class of invariant sub-Riemannian structures are organised as categories. The latter category is shown to be functorially equivalent to a subcategory of the former category. Via the Pontryagin Maximum Principle, we associate to each invariant optimal control problem (resp. invariant sub-Riemannian structure) a quadratic Hamilton-Poisson system on the associated Lie-Poisson space. These Hamiltonian systems are also organised as a category and hence the Pontryagin lift is realised as a contravariant functor. Basic properties of these categories are investigated. The rest of this thesis is concerned with the classification (and investigation) of certain subclasses of structures and systems. In the second chapter, the homogeneous positive semidefinite quadratic Hamilton-Poisson systems on three-dimensional Lie-Poisson spaces are classified up to compatibility with a linear isomorphism; a list of 23 normal forms is exhibited. In the third chapter, we classify the invariant sub-Riemannian structures in three dimensions and calculate the isometry group for each normal form. By comparing our results with known results, we show that most isometries (in three dimensions) are in fact the composition of a left translation and a Lie group isomorphism. In the fourth and last chapter of this thesis, we classify the sub-Riemannian and Riemannian structures on the (2n + 1)-dimensional Heisenberg groups. Furthermore, we find the isometry group and geodesics of each normal form.
- Full Text:
- Date Issued: 2015
Determination and validation of medicinal plants used by farmers to control internal and external parasites in goats in the Eastern Cape Province, South Africa
- Authors: Sanhokwe, Marcia
- Date: 2015
- Subjects: Medicinal plants -- South Africa -- Eastern Cape Goats -- Parasites -- Control
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2249 , vital:27718
- Description: The broad objective of the study was to determine and validate medicinal plants used by resource-limited farmers to control internal and external parasites in goats in the Eastern Cape Province, South Africa. A survey was conducted among 50 farmers and three herbalists to determine medicinal plants used to control parasites in goats. The survey revealed nine plant species belonging to eight families that were used. Among the identified plant species, Aloe ferox, Acokanthera oppositifolia and Elephantorrhiza elephantina were the plants having the highest Fidelity Level for their use, each scored 100.00 percent, followed by Albuca setosa (83.33 percent). These plants were then selected for validation studies. Gas-Chromatography-Mass-Spectrometry (GC-MS) revealed 7, 33, 26 and 32 bioactive phytochemicals in A. ferox, E. elephantina, A. oppositifolia and A. setosa, respectively. Terpenes and fatty acids were present, oxygenated terpenes being the most abundant hydrocarbons present in all the four plant species. The effect of acetone, methanol and ethanol extracts of leaves of Aloe ferox and Acokanthera oppositifolia on tick repellency and acaricidal activity were investigated on blood engorged Ambylomma hebraeum and Rhipicephalus decoloratus ticks at concentration 15, 30 and 50 percent. The 30 and 50 percent acetone extract of A. ferox and Dazzel dip had the highest acaricidal properties of 100 percent. The 50 percent methanol extract of A. oppositifolia and 50 percent acetone extract of A. ferox had the highest repellency activity of 89 percent and 85.33 percent, respectively. Results from this study revealed that the efficacy of medicinal plants used by farmers to control ticks vary with the type of solvent used for extracting the bioactive compounds. Furthermore, it revealed that Aloe ferox and A. opppositifolia plant extracts possess repellent and acaricidal activities. In a study to investigate the anthelminthic effect of crude extracts of Elephantorrhiza elephantina and Albuca setosa plants, significant anthelminthic effect on nematodes was observed in both plants. In this study, all E. elephantina and A. setosa extracts caused paralysis and mortality. Methanol was the most effective solvent in extracting bioactive compounds and methanol extract showed the best anthelminthic effects among the crude extracts investigated in both plants. The least time taken for the worms to be paralysed was 8.33 mins and 14.33mins in 100mg/ml methanol extracts of E. elephantina and A. setosa, resepectively. Methanol extract of E. elephantina and A. setosa (100mg/ml) had the highest anthelminthic activity and mortality was recorded after 18mins and 20mins, respectively. Results from this study revealed that these two plants possess anthelminthic activities. The study revealed that resource-limited farmers use medicinal plants to control internal and external parasites in goats. Gas-Chromatography-Mass-Spectrometry analysis showed that these plants contain bioactive compounds that have a potential in controlling parasites. Validation studies showed that A. ferox and A. oppositifolia possess repellent and acaricidal activities whereas A. setosa and E. elephantina possess anthelminthic activities.
- Full Text:
- Date Issued: 2015
- Authors: Sanhokwe, Marcia
- Date: 2015
- Subjects: Medicinal plants -- South Africa -- Eastern Cape Goats -- Parasites -- Control
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2249 , vital:27718
- Description: The broad objective of the study was to determine and validate medicinal plants used by resource-limited farmers to control internal and external parasites in goats in the Eastern Cape Province, South Africa. A survey was conducted among 50 farmers and three herbalists to determine medicinal plants used to control parasites in goats. The survey revealed nine plant species belonging to eight families that were used. Among the identified plant species, Aloe ferox, Acokanthera oppositifolia and Elephantorrhiza elephantina were the plants having the highest Fidelity Level for their use, each scored 100.00 percent, followed by Albuca setosa (83.33 percent). These plants were then selected for validation studies. Gas-Chromatography-Mass-Spectrometry (GC-MS) revealed 7, 33, 26 and 32 bioactive phytochemicals in A. ferox, E. elephantina, A. oppositifolia and A. setosa, respectively. Terpenes and fatty acids were present, oxygenated terpenes being the most abundant hydrocarbons present in all the four plant species. The effect of acetone, methanol and ethanol extracts of leaves of Aloe ferox and Acokanthera oppositifolia on tick repellency and acaricidal activity were investigated on blood engorged Ambylomma hebraeum and Rhipicephalus decoloratus ticks at concentration 15, 30 and 50 percent. The 30 and 50 percent acetone extract of A. ferox and Dazzel dip had the highest acaricidal properties of 100 percent. The 50 percent methanol extract of A. oppositifolia and 50 percent acetone extract of A. ferox had the highest repellency activity of 89 percent and 85.33 percent, respectively. Results from this study revealed that the efficacy of medicinal plants used by farmers to control ticks vary with the type of solvent used for extracting the bioactive compounds. Furthermore, it revealed that Aloe ferox and A. opppositifolia plant extracts possess repellent and acaricidal activities. In a study to investigate the anthelminthic effect of crude extracts of Elephantorrhiza elephantina and Albuca setosa plants, significant anthelminthic effect on nematodes was observed in both plants. In this study, all E. elephantina and A. setosa extracts caused paralysis and mortality. Methanol was the most effective solvent in extracting bioactive compounds and methanol extract showed the best anthelminthic effects among the crude extracts investigated in both plants. The least time taken for the worms to be paralysed was 8.33 mins and 14.33mins in 100mg/ml methanol extracts of E. elephantina and A. setosa, resepectively. Methanol extract of E. elephantina and A. setosa (100mg/ml) had the highest anthelminthic activity and mortality was recorded after 18mins and 20mins, respectively. Results from this study revealed that these two plants possess anthelminthic activities. The study revealed that resource-limited farmers use medicinal plants to control internal and external parasites in goats. Gas-Chromatography-Mass-Spectrometry analysis showed that these plants contain bioactive compounds that have a potential in controlling parasites. Validation studies showed that A. ferox and A. oppositifolia possess repellent and acaricidal activities whereas A. setosa and E. elephantina possess anthelminthic activities.
- Full Text:
- Date Issued: 2015
Preparation and use of maize tassels’ activated carbon for the adsorption of phenolic compounds in environmental waste water samples
- Olorundare, O F, Msagati, T A M, Okonkwo, J O, Krause, Rui W M, Mamba, Bhekie B
- Authors: Olorundare, O F , Msagati, T A M , Okonkwo, J O , Krause, Rui W M , Mamba, Bhekie B
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125331 , vital:35773 , https://doi.org/10.1007/s11356-014-3742-6
- Description: The determination and remediation of three phenolic compounds bisphenol A (BPA), ortho-nitrophenol (o-NTP), parachlorophenol (PCP) in wastewater is reported. The analysis of these molecules in wastewater was done using gas chromatography (GC) × GC time-of-flight mass spectrometry while activated carbon derived from maize tassel was used as an adsorbent. During the experimental procedures, the effect of various parameters such as initial concentration, pH of sample solution, eluent volume, and sample volume on the removal efficiency with respect to the three phenolic compounds was studied. The results showed that maize tassel produced activated carbon (MTAC) cartridge packed solid-phase extraction (SPE) system was able to remove the phenolic compounds effectively (90.84–98.49 %, 80.75–97.11 %, and 78.27–97.08 % for BPA, o-NTP, and PCP, respectively) . The MTAC cartridge packed SPE sorbent performance was compared to commercially produced C18 SPE cartridges and found to be comparable. All the parameters investigated were found to have a notable influence on the adsorption efficiency of the phenolic compounds from wastewaters at different magnitudes.
- Full Text:
- Date Issued: 2015
- Authors: Olorundare, O F , Msagati, T A M , Okonkwo, J O , Krause, Rui W M , Mamba, Bhekie B
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125331 , vital:35773 , https://doi.org/10.1007/s11356-014-3742-6
- Description: The determination and remediation of three phenolic compounds bisphenol A (BPA), ortho-nitrophenol (o-NTP), parachlorophenol (PCP) in wastewater is reported. The analysis of these molecules in wastewater was done using gas chromatography (GC) × GC time-of-flight mass spectrometry while activated carbon derived from maize tassel was used as an adsorbent. During the experimental procedures, the effect of various parameters such as initial concentration, pH of sample solution, eluent volume, and sample volume on the removal efficiency with respect to the three phenolic compounds was studied. The results showed that maize tassel produced activated carbon (MTAC) cartridge packed solid-phase extraction (SPE) system was able to remove the phenolic compounds effectively (90.84–98.49 %, 80.75–97.11 %, and 78.27–97.08 % for BPA, o-NTP, and PCP, respectively) . The MTAC cartridge packed SPE sorbent performance was compared to commercially produced C18 SPE cartridges and found to be comparable. All the parameters investigated were found to have a notable influence on the adsorption efficiency of the phenolic compounds from wastewaters at different magnitudes.
- Full Text:
- Date Issued: 2015
Application of Baylis-Hillman methodology in the synthesis of HIV-1 enzyme inhibitors
- Authors: Manyeruke, Meloddy Hlatini
- Date: 2015
- Subjects: HIV infections , Enzyme inhibitors , AZT (Drug) , Bioconjugates
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4540 , http://hdl.handle.net/10962/d1017920
- Description: The application of Baylis-Hillman methodology has afforded access to a range of β-hydroxypropionate ester-AZT conjugates as potential dual-action HIV-1 IN/RT inhibitors. Two families comprising a total of nine β-hydroxypropionate ester-AZT conjugates were synthesised. The first family was accessed using O-benzylated salicylaldehydes and methyl acrylate and the second from unprotected salicylaldehydes using tert-butyl acrylate as the activated alkene. Spectroscopic methods were employed to fully characterize the compounds. Propargylation of the respective Baylis-Hillman adducts was achieved via conjugate addition of propargylamine. The resulting products were then employed in Cu(I)-catalysed “click” reactions with azidothymidine (AZT) to yield the desired β-hydroxypropionate ester-AZT conjugates. Exploratory studies were also conducted to access 4-hydroxycoumarins from Baylis-Hillman derived adducts and to construct customized chiral Baylis-Hillman reaction sites. Many 4- hydroxycoumarins are known to exhibit a wide range of biological activities, and extending Baylis-Hillman methodology to access these systems is an important challenge. Two approaches were investigated. The first involved the formation of a 4-phthalimidocoumarin, aromatisation and hydrolysis of which was expected to lead to the 4-hydroxycoumarin target. The second, a variation of the first, involved the use of 4-(chrolomethyl)coumarin intermediates. Unfortunately, while various intermediates were prepared and characterised, neither approach led ultimately to the desired targets. N-substituted borneol-10-sulfonamides were constructed from camphor-10- sulfonyl chloride as chiral Baylis-Hillman reaction sites. In a preliminary study, however, none of the N-substituted borneol-10-sulfonamides exhibited Baylis-Hillman catalytic activity.
- Full Text:
- Date Issued: 2015
- Authors: Manyeruke, Meloddy Hlatini
- Date: 2015
- Subjects: HIV infections , Enzyme inhibitors , AZT (Drug) , Bioconjugates
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4540 , http://hdl.handle.net/10962/d1017920
- Description: The application of Baylis-Hillman methodology has afforded access to a range of β-hydroxypropionate ester-AZT conjugates as potential dual-action HIV-1 IN/RT inhibitors. Two families comprising a total of nine β-hydroxypropionate ester-AZT conjugates were synthesised. The first family was accessed using O-benzylated salicylaldehydes and methyl acrylate and the second from unprotected salicylaldehydes using tert-butyl acrylate as the activated alkene. Spectroscopic methods were employed to fully characterize the compounds. Propargylation of the respective Baylis-Hillman adducts was achieved via conjugate addition of propargylamine. The resulting products were then employed in Cu(I)-catalysed “click” reactions with azidothymidine (AZT) to yield the desired β-hydroxypropionate ester-AZT conjugates. Exploratory studies were also conducted to access 4-hydroxycoumarins from Baylis-Hillman derived adducts and to construct customized chiral Baylis-Hillman reaction sites. Many 4- hydroxycoumarins are known to exhibit a wide range of biological activities, and extending Baylis-Hillman methodology to access these systems is an important challenge. Two approaches were investigated. The first involved the formation of a 4-phthalimidocoumarin, aromatisation and hydrolysis of which was expected to lead to the 4-hydroxycoumarin target. The second, a variation of the first, involved the use of 4-(chrolomethyl)coumarin intermediates. Unfortunately, while various intermediates were prepared and characterised, neither approach led ultimately to the desired targets. N-substituted borneol-10-sulfonamides were constructed from camphor-10- sulfonyl chloride as chiral Baylis-Hillman reaction sites. In a preliminary study, however, none of the N-substituted borneol-10-sulfonamides exhibited Baylis-Hillman catalytic activity.
- Full Text:
- Date Issued: 2015
Photophysicochemical properties and in vitro photodynamic therapy activities of zinc phthalocyanine conjugates with biomolecules and single-walled carbon nanotubes
- Authors: Ogbodu, Racheal O
- Date: 2015
- Subjects: Photochemotherapy , Phthalocyanines , Biomolecules
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4544 , http://hdl.handle.net/10962/d1017924
- Description: The synthesis, photophysicochemcial properties, in vitro dark toxicity and photodynamic therapy (PDT) activities of different derivatives of zinc phthalocyanine (ZnPc) conjugates with biomolecules (folic acid, bovine serum albumin (BSA), ascorbic acid, uridine or spermine) and single-walled carbon nanotubes (SWCNTs) are presented in this work. The fluorescence quantum yields (ΦF) (Subscript F) of the ZnPc derivatives or ZnPc-biomolecule conjugates remained relatively the same as compared to the precursor Pcs. Slight increases were observed in the ΦF (Subscript F) values of conjugates containing substituents such as pyrene, folic acid or BSA with intrinsic fluorescence properties. The triplet quantum yield (ΦT ) (Subscript T) values for some ZnPc conjugates increases compared to the precursor ZnPcs due to extended π conjugation (for the conjugate with pyrene) and the presence of phenyl ring that support spin-orbit charge transfer intersystem crossing to triplet state. While some conjugates showed decreases in the ΦT (Subscript T) values compared to precursor ZnPcs due to the presence of substituents that could quench photo-excited state properties. The singlet oxygen quantum yield (ΦΔ ) values follow the trends of the triplet quantum yield values. The conjugates containing BSA also show increases in the ΦΔ values without corresponding increases in ΦT (Subscript T) values due to the ability of BSA to generate free radicals including singlet oxygen. The presence of SWCNTs decreases the photophysicochemcial properties of some ZnPc-SWCNT conjugates compared to the precursor ZnPcs due to photo-induced electron transfer from an excited Pc complex (electron donor) to SWCNTs (electron acceptor). However, increases were observed in some ZnPc-SWCNT conjugates as a result of fast charge recombination process due to highly short-lived radical ion pair produced. These phenomena affected the ΦF (Suscript F) values, ΦT (Suscript T) values, and the ΦΔ values. Increases or decreases in ΦT (Suscript T) values resulted in corresponding increases or decreases in ΦΔ values
- Full Text:
- Date Issued: 2015
- Authors: Ogbodu, Racheal O
- Date: 2015
- Subjects: Photochemotherapy , Phthalocyanines , Biomolecules
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4544 , http://hdl.handle.net/10962/d1017924
- Description: The synthesis, photophysicochemcial properties, in vitro dark toxicity and photodynamic therapy (PDT) activities of different derivatives of zinc phthalocyanine (ZnPc) conjugates with biomolecules (folic acid, bovine serum albumin (BSA), ascorbic acid, uridine or spermine) and single-walled carbon nanotubes (SWCNTs) are presented in this work. The fluorescence quantum yields (ΦF) (Subscript F) of the ZnPc derivatives or ZnPc-biomolecule conjugates remained relatively the same as compared to the precursor Pcs. Slight increases were observed in the ΦF (Subscript F) values of conjugates containing substituents such as pyrene, folic acid or BSA with intrinsic fluorescence properties. The triplet quantum yield (ΦT ) (Subscript T) values for some ZnPc conjugates increases compared to the precursor ZnPcs due to extended π conjugation (for the conjugate with pyrene) and the presence of phenyl ring that support spin-orbit charge transfer intersystem crossing to triplet state. While some conjugates showed decreases in the ΦT (Subscript T) values compared to precursor ZnPcs due to the presence of substituents that could quench photo-excited state properties. The singlet oxygen quantum yield (ΦΔ ) values follow the trends of the triplet quantum yield values. The conjugates containing BSA also show increases in the ΦΔ values without corresponding increases in ΦT (Subscript T) values due to the ability of BSA to generate free radicals including singlet oxygen. The presence of SWCNTs decreases the photophysicochemcial properties of some ZnPc-SWCNT conjugates compared to the precursor ZnPcs due to photo-induced electron transfer from an excited Pc complex (electron donor) to SWCNTs (electron acceptor). However, increases were observed in some ZnPc-SWCNT conjugates as a result of fast charge recombination process due to highly short-lived radical ion pair produced. These phenomena affected the ΦF (Suscript F) values, ΦT (Suscript T) values, and the ΦΔ values. Increases or decreases in ΦT (Suscript T) values resulted in corresponding increases or decreases in ΦΔ values
- Full Text:
- Date Issued: 2015
Investigating integrated catchment management using a simple water quantity and quality model : a case study of the Crocodile River Catchment, South Africa
- Retief, Daniel Christoffel Hugo
- Authors: Retief, Daniel Christoffel Hugo
- Date: 2015
- Subjects: Watersheds -- South Africa -- Krokodilrivier (Mpumalanga) , Integrated water development -- South Africa -- Krokodilrivier (Mpumalanga) , Water quality management -- South Africa -- Krokodilrivier (Mpumalanga) , Water-supply -- South Africa -- Krokodilrivier (Mpumalanga) , Water quality -- Measurement
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6050 , http://hdl.handle.net/10962/d1017875
- Description: Internationally, water resources are facing increasing pressure due to over-exploitation and pollution. Integrated Water Resource Management (IWRM) has been accepted internationally as a paradigm for integrative and sustainable management of water resources. However, in practice, the implementation and success of IWRM policies has been hampered by the lack of availability of integrative decision support tools, especially within the context of limited resources and observed data. This is true for the Crocodile River Catchment (CRC), located within the Mpumalanga Province of South Africa. The catchment has been experiencing a decline in water quality as a result of the point source input of a cocktail of pollutants, which are discharged from industrial and municipal wastewater treatment plants, as well as diffuse source runoff and return flows from the extensive areas of irrigated agriculture and mining sites. The decline in water quality has profound implications for a range of stakeholders across the catchment including increased treatment costs and reduced crop yields. The combination of deteriorating water quality and the lack of understanding of the relationships between water quantity and quality for determining compliance/non-compliance in the CRC have resulted in collaboration between stakeholders, willing to work in a participatory and transparent manner to create an Integrated Water Quality Management Plan (IWQMP). This project aimed to model water quality, (combined water quality and quantity), to facilitate the IWQMP aiding in the understanding of the relationship between water quantity and quality in the CRC. A relatively simple water quality model (WQSAM) was used that receives inputs from established water quantity systems models, and was designed to be a water quality decision support tool for South African catchments. The model was applied to the CRC, achieving acceptable simulations of total dissolved solids (used as a surrogate for salinity) and nutrients (including orthophosphates, nitrates +nitrites and ammonium) for historical conditions. Validation results revealed that there is little consistency within the catchment, attributed to the non-stationary nature of water quality at many of the sites in the CRC. The analyses of the results using a number of representations including, seasonal load distributions, load duration curves and load flow plots, confirmed that the WQSAM model was able to capture the variability of relationships between water quantity and quality, provided that simulated hydrology was sufficiently accurate. The outputs produced by WQSAM was seen as useful for the CRC, with the Inkomati-Usuthu Catchment Management Agency (IUCMA) planning to operationalise the model in 2015. The ability of WQSAM to simulate water quality in data scarce catchments, with constituents that are appropriate for the needs of water resource management within South Africa, is highly beneficial.
- Full Text:
- Date Issued: 2015
- Authors: Retief, Daniel Christoffel Hugo
- Date: 2015
- Subjects: Watersheds -- South Africa -- Krokodilrivier (Mpumalanga) , Integrated water development -- South Africa -- Krokodilrivier (Mpumalanga) , Water quality management -- South Africa -- Krokodilrivier (Mpumalanga) , Water-supply -- South Africa -- Krokodilrivier (Mpumalanga) , Water quality -- Measurement
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6050 , http://hdl.handle.net/10962/d1017875
- Description: Internationally, water resources are facing increasing pressure due to over-exploitation and pollution. Integrated Water Resource Management (IWRM) has been accepted internationally as a paradigm for integrative and sustainable management of water resources. However, in practice, the implementation and success of IWRM policies has been hampered by the lack of availability of integrative decision support tools, especially within the context of limited resources and observed data. This is true for the Crocodile River Catchment (CRC), located within the Mpumalanga Province of South Africa. The catchment has been experiencing a decline in water quality as a result of the point source input of a cocktail of pollutants, which are discharged from industrial and municipal wastewater treatment plants, as well as diffuse source runoff and return flows from the extensive areas of irrigated agriculture and mining sites. The decline in water quality has profound implications for a range of stakeholders across the catchment including increased treatment costs and reduced crop yields. The combination of deteriorating water quality and the lack of understanding of the relationships between water quantity and quality for determining compliance/non-compliance in the CRC have resulted in collaboration between stakeholders, willing to work in a participatory and transparent manner to create an Integrated Water Quality Management Plan (IWQMP). This project aimed to model water quality, (combined water quality and quantity), to facilitate the IWQMP aiding in the understanding of the relationship between water quantity and quality in the CRC. A relatively simple water quality model (WQSAM) was used that receives inputs from established water quantity systems models, and was designed to be a water quality decision support tool for South African catchments. The model was applied to the CRC, achieving acceptable simulations of total dissolved solids (used as a surrogate for salinity) and nutrients (including orthophosphates, nitrates +nitrites and ammonium) for historical conditions. Validation results revealed that there is little consistency within the catchment, attributed to the non-stationary nature of water quality at many of the sites in the CRC. The analyses of the results using a number of representations including, seasonal load distributions, load duration curves and load flow plots, confirmed that the WQSAM model was able to capture the variability of relationships between water quantity and quality, provided that simulated hydrology was sufficiently accurate. The outputs produced by WQSAM was seen as useful for the CRC, with the Inkomati-Usuthu Catchment Management Agency (IUCMA) planning to operationalise the model in 2015. The ability of WQSAM to simulate water quality in data scarce catchments, with constituents that are appropriate for the needs of water resource management within South Africa, is highly beneficial.
- Full Text:
- Date Issued: 2015
Contributions to the study of a class of optimal control problems on the orthogonal groups SO(3) and SO(4)
- Authors: Adams, Ross Montague
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64826 , vital:28608
- Description: In this thesis we investigate a class of invariant optimal control problems, and their associated quadratic Hamilton-Poisson systems, on the orthogonal groups SO(3) and SO(4). Specifically, we are concerned with the class of left-invariant control affine systems. We begin by classifying all cost-extended systems on SO(3) under cost equivalence. (Cost-extended systems are closely related to optimal control problems.) A classification of all quadratic Hamilton-Poisson systems on the (minus) Lie-Poisson space so(3)*, under affine equivalence, is also obtained. For the normal forms obtained in our classification (of Hamilton-Poisson systems) we investigate the (Lyapunov) stability nature of the equilibria using spectral and energy-Casimir methods. For a subclass of these systems, we obtain analytic expressions for the integral curves of the associated Hamiltonian vector fields in terms of (basic) Jacobi elliptic functions. The explicit relationship between the classification of cost-extended systems on SO(3) and the classification of quadratic Hamilton- Poisson systems on so(3)* is provided. On SO(4), a classification of all left-invariant control affine systems under L-equivalence is obtained. We then determine which of these representatives are controllable, thus obtaining a classification under detached feedback equivalence. We also obtain a partial classification of quadratic Hamilton-Poisson systems on the Lie-Poisson space so(4)*. An investigation of the stability nature of the equilibria for a subclass of these systems is also done. Several illustrative examples of optimal control problems on the orthogonal group SO(3) are provided. More specifically, we consider an optimal control problem corresponding to a representative of our classification (of cost-extended system) for each possible number of control inputs. For each of these problems, we obtain explicit expressions for the extremal trajectories on the homogeneous space S2 by projecting the extremal trajectories on the group SO(3). The examples provided show how our classifications of cost-extended systems and Hamilton-Poisson systems can be used to obtain the optimal controls and the extremal trajectories corresponding to a large class of optimal control problems on SO(3). An example of a four-input optimal control problem on SO(4) is also provided. This example is provided to show how the solutions of certain problems on SO(4) can be related to the solutions of certain optimal control problems on SO(3).
- Full Text:
- Date Issued: 2015
- Authors: Adams, Ross Montague
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64826 , vital:28608
- Description: In this thesis we investigate a class of invariant optimal control problems, and their associated quadratic Hamilton-Poisson systems, on the orthogonal groups SO(3) and SO(4). Specifically, we are concerned with the class of left-invariant control affine systems. We begin by classifying all cost-extended systems on SO(3) under cost equivalence. (Cost-extended systems are closely related to optimal control problems.) A classification of all quadratic Hamilton-Poisson systems on the (minus) Lie-Poisson space so(3)*, under affine equivalence, is also obtained. For the normal forms obtained in our classification (of Hamilton-Poisson systems) we investigate the (Lyapunov) stability nature of the equilibria using spectral and energy-Casimir methods. For a subclass of these systems, we obtain analytic expressions for the integral curves of the associated Hamiltonian vector fields in terms of (basic) Jacobi elliptic functions. The explicit relationship between the classification of cost-extended systems on SO(3) and the classification of quadratic Hamilton- Poisson systems on so(3)* is provided. On SO(4), a classification of all left-invariant control affine systems under L-equivalence is obtained. We then determine which of these representatives are controllable, thus obtaining a classification under detached feedback equivalence. We also obtain a partial classification of quadratic Hamilton-Poisson systems on the Lie-Poisson space so(4)*. An investigation of the stability nature of the equilibria for a subclass of these systems is also done. Several illustrative examples of optimal control problems on the orthogonal group SO(3) are provided. More specifically, we consider an optimal control problem corresponding to a representative of our classification (of cost-extended system) for each possible number of control inputs. For each of these problems, we obtain explicit expressions for the extremal trajectories on the homogeneous space S2 by projecting the extremal trajectories on the group SO(3). The examples provided show how our classifications of cost-extended systems and Hamilton-Poisson systems can be used to obtain the optimal controls and the extremal trajectories corresponding to a large class of optimal control problems on SO(3). An example of a four-input optimal control problem on SO(4) is also provided. This example is provided to show how the solutions of certain problems on SO(4) can be related to the solutions of certain optimal control problems on SO(3).
- Full Text:
- Date Issued: 2015
Characterisation of the HSP70-HSP90 organising protein gene and its link to cancer
- Authors: Weeks, Stacey
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/56006 , vital:26764
- Description: HOP (Heat shock protein 70/ Heat shock protein 90 organising protein) is a co-chaperone essential for client protein transfer from HSP70 to HSP90 within the HSP90 chaperone machine and has been found to be up-regulated in various cancers. However, minimal in vitro information can be found on the regulation of HOP expression. The aim of this study was to analyse the HOP gene structure across known orthologues, identify and characterise the HOP promoter, and identify the regulatory mechanisms influencing the expression of HOP in cancer. We hypothesized that the expression of HOP in cancer cells is likely regulated by oncogenic signalling pathways linked to cis-elements within the HOP promoter. An initial study of the evolution of the HOP gene speciation was performed across identified orthologues using Mega5.2. The evolutionary pathway of the HOP gene was traced from the unicellular organisms to fish, to amphibian and then to land mammal. The synteny across the orthologues was identified and the co-expression profile of HOP analysed. We identified the putative promoter region for HOP in silico and in vitro. Luciferase reporter assays were utilized to demonstrate promoter activity of the upstream region in vitro. Bioinformatic analysis of the active promoter region identified a large CpG island and a range of putative cis-elements. Many of the cis-elements interact with transcription factors which are activated by oncogenic pathways. We therefore tested the regulation of HOP levels by rat sarcoma viral oncogene homologue (RAS). Cancer cell lines were transfected with mutated RAS to observe the effect of constitutively active RAS expression on the production of HOP using qRT-PCR and Western Blot analyses. Additionally, inhibitors of the RAS signalling pathway were utilised to confirm the regulatory effect of mutated RAS on HOP expression. In cancer cell lines containing mutated RAS (Hs578T), HOP was up-regulated via a mechanism involving the MAPK signalling pathway and the ETS-1 and C/EBPβ cis-elements within the HOP promoter. These findings suggest for the first time that Hop expression in cancer may be regulated by RAS activation of the HOP promoter. Additionally, this study allowed us to determine the murine system to be the most suited genetic model organism with which to study the function of human HOP.
- Full Text:
- Date Issued: 2015
- Authors: Weeks, Stacey
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/56006 , vital:26764
- Description: HOP (Heat shock protein 70/ Heat shock protein 90 organising protein) is a co-chaperone essential for client protein transfer from HSP70 to HSP90 within the HSP90 chaperone machine and has been found to be up-regulated in various cancers. However, minimal in vitro information can be found on the regulation of HOP expression. The aim of this study was to analyse the HOP gene structure across known orthologues, identify and characterise the HOP promoter, and identify the regulatory mechanisms influencing the expression of HOP in cancer. We hypothesized that the expression of HOP in cancer cells is likely regulated by oncogenic signalling pathways linked to cis-elements within the HOP promoter. An initial study of the evolution of the HOP gene speciation was performed across identified orthologues using Mega5.2. The evolutionary pathway of the HOP gene was traced from the unicellular organisms to fish, to amphibian and then to land mammal. The synteny across the orthologues was identified and the co-expression profile of HOP analysed. We identified the putative promoter region for HOP in silico and in vitro. Luciferase reporter assays were utilized to demonstrate promoter activity of the upstream region in vitro. Bioinformatic analysis of the active promoter region identified a large CpG island and a range of putative cis-elements. Many of the cis-elements interact with transcription factors which are activated by oncogenic pathways. We therefore tested the regulation of HOP levels by rat sarcoma viral oncogene homologue (RAS). Cancer cell lines were transfected with mutated RAS to observe the effect of constitutively active RAS expression on the production of HOP using qRT-PCR and Western Blot analyses. Additionally, inhibitors of the RAS signalling pathway were utilised to confirm the regulatory effect of mutated RAS on HOP expression. In cancer cell lines containing mutated RAS (Hs578T), HOP was up-regulated via a mechanism involving the MAPK signalling pathway and the ETS-1 and C/EBPβ cis-elements within the HOP promoter. These findings suggest for the first time that Hop expression in cancer may be regulated by RAS activation of the HOP promoter. Additionally, this study allowed us to determine the murine system to be the most suited genetic model organism with which to study the function of human HOP.
- Full Text:
- Date Issued: 2015
Investigation into the characteristics and possible applications of biomass gasification by-products from a downdraft gasifier system
- Authors: Melapi, Aviwe
- Date: 2015
- Subjects: Biomass gasification -- South Africa -- Eastern Cape , Renewable energy sources -- South Africa -- Eastern Cape , Biomass energy -- South Africa -- Eastern Cape , Crop residue management -- South Africa -- Eastern Cape , Coal gasification -- South Africa -- Eastern Cape , Lignocellulose -- Biodegradation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11348 , http://hdl.handle.net/10353/d1020174 , Biomass gasification -- South Africa -- Eastern Cape , Renewable energy sources -- South Africa -- Eastern Cape , Biomass energy -- South Africa -- Eastern Cape , Crop residue management -- South Africa -- Eastern Cape , Coal gasification -- South Africa -- Eastern Cape , Lignocellulose -- Biodegradation -- South Africa -- Eastern Cape
- Description: Biomass gasification has attracted the interest of researchers because it produces zero carbon to the atmosphere. This technology does not only produce syngas but also the byproducts which can be used for various application depending on quality.The study conducted at Melani village in Alice in the Eastern Cape of South Africa was aimed at investigating the possible applications of the gasification byproducts instead of being thrown away. Pine wood was employed as the parent feedstock material for the gasifier. Biomass gasification by-products were then collected for further analysis. The studied by-products included tar(condensate), char, soot and resin. These materials were also blended to produce strong materials.The essence of the blending was to generate ideal material that is strong but light at the same time.The elemental analysis of the samples performed by CHNS analyser revealed that carbon element is in large quantities in all samples. The FTIR spectra showed almost similar results for all the studied samples, since the samples are end products of lignocellulosegasification. SEM gave the sticky images of resin as well as porous char structures. Char showed a higher heating value of 35.37MJ/Kg when compared to other by-products samples.
- Full Text:
- Date Issued: 2015
- Authors: Melapi, Aviwe
- Date: 2015
- Subjects: Biomass gasification -- South Africa -- Eastern Cape , Renewable energy sources -- South Africa -- Eastern Cape , Biomass energy -- South Africa -- Eastern Cape , Crop residue management -- South Africa -- Eastern Cape , Coal gasification -- South Africa -- Eastern Cape , Lignocellulose -- Biodegradation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11348 , http://hdl.handle.net/10353/d1020174 , Biomass gasification -- South Africa -- Eastern Cape , Renewable energy sources -- South Africa -- Eastern Cape , Biomass energy -- South Africa -- Eastern Cape , Crop residue management -- South Africa -- Eastern Cape , Coal gasification -- South Africa -- Eastern Cape , Lignocellulose -- Biodegradation -- South Africa -- Eastern Cape
- Description: Biomass gasification has attracted the interest of researchers because it produces zero carbon to the atmosphere. This technology does not only produce syngas but also the byproducts which can be used for various application depending on quality.The study conducted at Melani village in Alice in the Eastern Cape of South Africa was aimed at investigating the possible applications of the gasification byproducts instead of being thrown away. Pine wood was employed as the parent feedstock material for the gasifier. Biomass gasification by-products were then collected for further analysis. The studied by-products included tar(condensate), char, soot and resin. These materials were also blended to produce strong materials.The essence of the blending was to generate ideal material that is strong but light at the same time.The elemental analysis of the samples performed by CHNS analyser revealed that carbon element is in large quantities in all samples. The FTIR spectra showed almost similar results for all the studied samples, since the samples are end products of lignocellulosegasification. SEM gave the sticky images of resin as well as porous char structures. Char showed a higher heating value of 35.37MJ/Kg when compared to other by-products samples.
- Full Text:
- Date Issued: 2015