Integration of nanostructured metal sulfides into titanium (iv) oxide for high performance dye sensitized solar cell
- Adedoyin Mojeed Agoro https://orcid.org/0000-0002-0434-9635
- Authors: Adedoyin Mojeed Agoro https://orcid.org/0000-0002-0434-9635
- Date: 2020-01
- Subjects: Nanostructured materials , Sulfur compounds
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21523 , vital:48857
- Description: The work in this thesis describes synthesis, characterization and integration of nanostructured metal sulfides into titanium (IV) oxide for high performance dye sensitized solar cell. The synthesised single source precursors were evaluated using TGA, FTIR, , UV-Vis, PL,1H and 13CNMR, SEM, EDS, HRTEM, XRD, AFM, Raman, I-V, CV, Bode plot and EIS. TGA revealed the thermal degradation and quantified the mass percentage of metal sulphides as 33percent, 45percent and 27percent for CuS, PbS and SnS nanoparticles, respectively. FTIR analysis showed bands at 1580-1450 cm-1, and 1060-940 cm-1 tentatively assigned to C-N and C-S stretching frequencies correspondingly. The (M-S) stretching was observed at 577-406 cm-1 for the complexes using bis(N-di-isopropyl-N-octyldithiocarbamato) as primary ligands. IR spectra of bis(N-1,4-phenyl-N-(4-morpholinedithiocarbamato) as secondary ligands suggested the presence of (C-N) vibrations at 1508-1513 cm-1 for the complexes and 1507-1584 cm-1 for the ligands. The bands in the region of 973-1030 cm-1 were assigned to the complexes and 974- 983 cm-1 were attributed to the ligands, whereas vibration frequencies at 416-625 cm-1 were Nelson's Choice were included in these preliminary variety trials (PVTs) as checks. Twenty-five hybrids expressing high values for the Smith – Hazel selection index were identified across sites over years. Among those hybrids were two checks, namely Q16 (PAN5Q649R) and Q33 (Phb31MO7BR). The top five high – yielding hybrids selected based on the selection index were considered to be the most productive, stable and adaptable based on the GGE biplot and AMMI stability values. None of these single cross hybrids over yielded the best hybrid check (Q16) in the current study. A high potential environment, Centane, was the ideal environments for evaluating genotypes in the present study. The studies showed inbred lines L22, L23, L26, L28, L25, L29 and L31 to be low N stress tolerant at 0 kg N ha-1 based on the low N stress tolerance indices under glasshouse and the field conditions; they were also among the top ten grain-yielders under field conditions at 0 kg N ha-1. Also, in the NUE study, they were found to be among the top ten most N-efficient inbred lines under low N soils, under 30 kg N ha-1, and were among the top twenty-four inbred lines with high NUE values across the N levels in the study. Inbred lines L29 and L22 also produced testcross hybrids that were among the top twenty based on GY under 0 kg N ha-1. The testcross hybrids produced from these inbred lines were also among the top twenty-five with outstanding SCA effects for GY. These inbred lines were also parental lines of some of the top twenty- five best hybrids selected based on the Smith – Hazel selection index in the PVT study. Inbred lines L22, L23, L26, L28, L25, L29 and L31 can therefore further be evaluated and used as sources of N-tolerance genes in QPM breeding programs. tentatively assigned to M-S bond in the complexes. UV-Vis spectroscopy analysis for the complexes and from primary and secondary ligands are between within the range of 338 – 340 nm. PL studies of the primary ligands with metal complexes indicated emissions at 464 nm, 462 nm, 462 nm for Pb(II) and Sn(II), and Cu(II). The presence of secondary ligands was revealed by the absorption peaks at 455, 456 and 457 nm, exhibiting both the signals and chemical constituents of the respective ligands and their corresponding complexes. The electrochemistry in chapters 3 and 4 reveals that phase angle in the Bode plots changes with frequencies for Sn(II) complexes at 58, 57 and 8 respectively. Bode plots showed remarkable electronics of Cu(II) and Pb(II) complex interfaces. The CV curves exhibit two kinds of redox peaks indicating reduction at the negative potentials and oxidation at the positive potentials. The EIS, electrodes produced Rct for Pb(II), Cu(II) and Sn(II) electrodes in chapter 3. Moreover The EIS revealed that Sn(II) sensitizer displaced a stronger chemical capacitance and improved efficiency which could lead to better electron lifetime yield. The obtained CV exhibited anodic and cathodic peaks for Pb(II), connoting a reduction in Pb2+ and oxidation in Pb2-. Bode plot phase angle displayed Sn(II) and Pb(II) with maxima phase, indicating the presence of time constants of the electrode processes in Bis(N-1,4-Phenyl-N-Morhpo-dithiocarbamato bis(Mo/1,4-PHDTC) complexes. From the results in chapter 4, the XRD patterns exhibited good crystalline nature of CuS as a result of sharp and strong diffraction peaks obtained. There are eight peaks of 2θ angle between 26° and 79° relating to orthorhombic structure of SnS. While PbS has a cubic structure with polycrystalline nature, PbS/HDA and PbS both correspond to their crystalline planes of (200), (111), (220), (311), (222), (400), (331), (420) and (422) affirming to PbS QDs structure. SnS/HDA and SnS photosensitizers displayed eleven peaks between the values of 27.02° to 66.05° for SnS/HDA and 26.03° to 66.04° for SnS, in confirming the orthorhombic structure. SEM analysis revealed hexagonal structure for CuS, while PbS and SnS exhibited mesoporous nanostructures with spherical nanoparticles. HRTEM images indicated spherical nano-particles with particle sizes in the range of 3.14 - 44.39 nm. The outcome of HRTEM analysis revealed crystallite sizes varying as 10.90 – 11.57 nm, 3.14 – 5.95 nm and 14.96 – 44.39 nm for the CuS, PbS and SnS, originated from the primary ligands. HRTEM images originating from the Bis(N-1,4-Phenyl-N-Morhpo-dithiocarbamato bis(Mo/1,4-PHDTC) complexes indicated spherical nano-particles with particle sizes of 3.14 - 44.39 nm. Raman images in chapter 5 revealed the presence of Raman active modes of E2g 66 cm-1 and 304, cm-1 and E1g 627 cm-1 and 706 cm-1 for CuS, the active modes of TO 65 cm-1 and 2LO 626 cm-1 for PbS, active modes of B1g 69 cm-1 for SnS and 266 cm-1 for Ag. From the AFM results in chapter 5, CuS photosensitizer displayed a smooth surface and particle estimated to be 0.50 μm and height profile of 12percent. The PbS photosensitizer exhibited particle size of 1.82 μm and 0.654 μm for PbS/HDA, depicting a regular crystal growth rate. The size distribution of SnS nanoparticle at 357 nm connotes smooth surface and good compactness on the substrate. However, SnS/HDA at 122 nm displayed shape and size of non-symmetrical particles. AFM analysis in chapter 8 revealed good size roughness for CuS film. PbS exhibited particle size of 365 nm and size height of 18percent as the smoothest film, while PbS/HDA revealed 1.22 um size with 9percent size height. The evaluated particle sizes varied as 0.11- 1.18 um for SnS/HDA and 0.054 – 0.54 um for SnS films grown at 360 ℃ with size height of 16.8 and 8.4percent. The I-V efficiency obtained indicated that the CuS exhibited a much better efficiency in the QDSCs with higher Voc and the highest η being 2.85percent compared to CuS/HDA and Cu(II). High JSC of 11 mA/cm has been observed in the PbS/HDA QDSSCs, compared to the PbS and Pb(II) cells. The SnS/HDA exhibited a better performance compared to SnS and Sn(II) sensitizers due to the presence of HDA capping agent. , Thesis (MSc -- Faculty of Science and Agriculture, 2020
- Full Text:
- Date Issued: 2020-01
- Authors: Adedoyin Mojeed Agoro https://orcid.org/0000-0002-0434-9635
- Date: 2020-01
- Subjects: Nanostructured materials , Sulfur compounds
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21523 , vital:48857
- Description: The work in this thesis describes synthesis, characterization and integration of nanostructured metal sulfides into titanium (IV) oxide for high performance dye sensitized solar cell. The synthesised single source precursors were evaluated using TGA, FTIR, , UV-Vis, PL,1H and 13CNMR, SEM, EDS, HRTEM, XRD, AFM, Raman, I-V, CV, Bode plot and EIS. TGA revealed the thermal degradation and quantified the mass percentage of metal sulphides as 33percent, 45percent and 27percent for CuS, PbS and SnS nanoparticles, respectively. FTIR analysis showed bands at 1580-1450 cm-1, and 1060-940 cm-1 tentatively assigned to C-N and C-S stretching frequencies correspondingly. The (M-S) stretching was observed at 577-406 cm-1 for the complexes using bis(N-di-isopropyl-N-octyldithiocarbamato) as primary ligands. IR spectra of bis(N-1,4-phenyl-N-(4-morpholinedithiocarbamato) as secondary ligands suggested the presence of (C-N) vibrations at 1508-1513 cm-1 for the complexes and 1507-1584 cm-1 for the ligands. The bands in the region of 973-1030 cm-1 were assigned to the complexes and 974- 983 cm-1 were attributed to the ligands, whereas vibration frequencies at 416-625 cm-1 were Nelson's Choice were included in these preliminary variety trials (PVTs) as checks. Twenty-five hybrids expressing high values for the Smith – Hazel selection index were identified across sites over years. Among those hybrids were two checks, namely Q16 (PAN5Q649R) and Q33 (Phb31MO7BR). The top five high – yielding hybrids selected based on the selection index were considered to be the most productive, stable and adaptable based on the GGE biplot and AMMI stability values. None of these single cross hybrids over yielded the best hybrid check (Q16) in the current study. A high potential environment, Centane, was the ideal environments for evaluating genotypes in the present study. The studies showed inbred lines L22, L23, L26, L28, L25, L29 and L31 to be low N stress tolerant at 0 kg N ha-1 based on the low N stress tolerance indices under glasshouse and the field conditions; they were also among the top ten grain-yielders under field conditions at 0 kg N ha-1. Also, in the NUE study, they were found to be among the top ten most N-efficient inbred lines under low N soils, under 30 kg N ha-1, and were among the top twenty-four inbred lines with high NUE values across the N levels in the study. Inbred lines L29 and L22 also produced testcross hybrids that were among the top twenty based on GY under 0 kg N ha-1. The testcross hybrids produced from these inbred lines were also among the top twenty-five with outstanding SCA effects for GY. These inbred lines were also parental lines of some of the top twenty- five best hybrids selected based on the Smith – Hazel selection index in the PVT study. Inbred lines L22, L23, L26, L28, L25, L29 and L31 can therefore further be evaluated and used as sources of N-tolerance genes in QPM breeding programs. tentatively assigned to M-S bond in the complexes. UV-Vis spectroscopy analysis for the complexes and from primary and secondary ligands are between within the range of 338 – 340 nm. PL studies of the primary ligands with metal complexes indicated emissions at 464 nm, 462 nm, 462 nm for Pb(II) and Sn(II), and Cu(II). The presence of secondary ligands was revealed by the absorption peaks at 455, 456 and 457 nm, exhibiting both the signals and chemical constituents of the respective ligands and their corresponding complexes. The electrochemistry in chapters 3 and 4 reveals that phase angle in the Bode plots changes with frequencies for Sn(II) complexes at 58, 57 and 8 respectively. Bode plots showed remarkable electronics of Cu(II) and Pb(II) complex interfaces. The CV curves exhibit two kinds of redox peaks indicating reduction at the negative potentials and oxidation at the positive potentials. The EIS, electrodes produced Rct for Pb(II), Cu(II) and Sn(II) electrodes in chapter 3. Moreover The EIS revealed that Sn(II) sensitizer displaced a stronger chemical capacitance and improved efficiency which could lead to better electron lifetime yield. The obtained CV exhibited anodic and cathodic peaks for Pb(II), connoting a reduction in Pb2+ and oxidation in Pb2-. Bode plot phase angle displayed Sn(II) and Pb(II) with maxima phase, indicating the presence of time constants of the electrode processes in Bis(N-1,4-Phenyl-N-Morhpo-dithiocarbamato bis(Mo/1,4-PHDTC) complexes. From the results in chapter 4, the XRD patterns exhibited good crystalline nature of CuS as a result of sharp and strong diffraction peaks obtained. There are eight peaks of 2θ angle between 26° and 79° relating to orthorhombic structure of SnS. While PbS has a cubic structure with polycrystalline nature, PbS/HDA and PbS both correspond to their crystalline planes of (200), (111), (220), (311), (222), (400), (331), (420) and (422) affirming to PbS QDs structure. SnS/HDA and SnS photosensitizers displayed eleven peaks between the values of 27.02° to 66.05° for SnS/HDA and 26.03° to 66.04° for SnS, in confirming the orthorhombic structure. SEM analysis revealed hexagonal structure for CuS, while PbS and SnS exhibited mesoporous nanostructures with spherical nanoparticles. HRTEM images indicated spherical nano-particles with particle sizes in the range of 3.14 - 44.39 nm. The outcome of HRTEM analysis revealed crystallite sizes varying as 10.90 – 11.57 nm, 3.14 – 5.95 nm and 14.96 – 44.39 nm for the CuS, PbS and SnS, originated from the primary ligands. HRTEM images originating from the Bis(N-1,4-Phenyl-N-Morhpo-dithiocarbamato bis(Mo/1,4-PHDTC) complexes indicated spherical nano-particles with particle sizes of 3.14 - 44.39 nm. Raman images in chapter 5 revealed the presence of Raman active modes of E2g 66 cm-1 and 304, cm-1 and E1g 627 cm-1 and 706 cm-1 for CuS, the active modes of TO 65 cm-1 and 2LO 626 cm-1 for PbS, active modes of B1g 69 cm-1 for SnS and 266 cm-1 for Ag. From the AFM results in chapter 5, CuS photosensitizer displayed a smooth surface and particle estimated to be 0.50 μm and height profile of 12percent. The PbS photosensitizer exhibited particle size of 1.82 μm and 0.654 μm for PbS/HDA, depicting a regular crystal growth rate. The size distribution of SnS nanoparticle at 357 nm connotes smooth surface and good compactness on the substrate. However, SnS/HDA at 122 nm displayed shape and size of non-symmetrical particles. AFM analysis in chapter 8 revealed good size roughness for CuS film. PbS exhibited particle size of 365 nm and size height of 18percent as the smoothest film, while PbS/HDA revealed 1.22 um size with 9percent size height. The evaluated particle sizes varied as 0.11- 1.18 um for SnS/HDA and 0.054 – 0.54 um for SnS films grown at 360 ℃ with size height of 16.8 and 8.4percent. The I-V efficiency obtained indicated that the CuS exhibited a much better efficiency in the QDSCs with higher Voc and the highest η being 2.85percent compared to CuS/HDA and Cu(II). High JSC of 11 mA/cm has been observed in the PbS/HDA QDSSCs, compared to the PbS and Pb(II) cells. The SnS/HDA exhibited a better performance compared to SnS and Sn(II) sensitizers due to the presence of HDA capping agent. , Thesis (MSc -- Faculty of Science and Agriculture, 2020
- Full Text:
- Date Issued: 2020-01
Characterization of bioflocculants produced by consortia of three marine bacteria belonging to the genera bacillus and cobetia previously isolated from the bottom sediment of Algoa Bay in the Eastern Cape Province of South Africa
- Ugbenyen, Anthony Moses https://orcid.org/0000-0002-1381-3428
- Authors: Ugbenyen, Anthony Moses https://orcid.org/0000-0002-1381-3428
- Date: 2013
- Subjects: Water -- Purification -- Flocculation , Water quality management , Flocculation
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24454 , vital:62804
- Description: The bioflocculant-producing potentials of three marine bacteria isolated from the sediment samples of Algoa Bay in the Eastern Cape Province of South Africa were assessed. Analysis of the partial nucleotide sequence of the 16S rDNA of the bacteria revealed 99 percent, 99 percent, and 98 percent similarity to Cobetia sp. L222, Bacillus sp. A-5A, and Bacillus sp. HXG-C1 respectively and the sequence was deposited in GenBank as Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert (accession number JF799092, JF799093, and HQ537128 respectively). Cultivation condition studies for Cobetia sp. OAUIFE revealed that bioflocculant production was optimal with an inoculum size of 2 percent (v/v), initial pH of 6.0, Mn2+ as the metal ion, and glucose as the carbon source. Metal ions, including Na+, K+, Li+, Ca2+and Mg2+ stimulated bioflocculant production resulting in flocculating activity of above 90 percent. This crude bioflocculant is thermally stable, with about 78 percent of its flocculating activity remaining after heating at 100 oC for 25 min. Analysis of the purified bioflocculant revealed it to be an acidic extracellular polysaccharide. FTIR analysis revealed the presence of methoxyl, hydroxyl, and carboxyl - groups in the compound bioflocculant and SEM micrograph of the bioflocculant revealed a crystal-linear structure. On the other hand, bioflocculant production by Bacillus sp. MAYA was optimal when glucose (95.6 percent flocculating activity) and ammonium nitrate (83.3 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 2 percent (v/v); initial pH 6; and Ca2+ as coagulant aid. Chemical analysis of the purified bioflocculant shows that it is composed of uronic acid, neutral sugar and protein. FTIR analysis also revealed the presence of methoxyl, hydroxyl, carboxyl and amino- groups in this bioflocculant. The bioflocculant is thermostable with about 65.6 percent residual flocculating activity retained after heating the bioflocculant at 100 oC for 25 min. However bioflocculant production by Bacillus sp. Gilbert was optimal when sodium carbonate (95.2 percent flocculating activity) and potassium nitrate (76.6 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 3 percent (v/v); initial pH 9; and Al3+ as cation. The crude bioflocculant retained 44.2 percent residual flocculating activity after heating at 100 oC for 15 min. FTIR analysis reveals the presence of hydroxyl, carboxyl and methylene - groups in the compound bioflocculant. SEM micrograph of the bioflocculant revealed an amorphous compound. The consortia of these bacteria strains also produced bioflocculants with high flocculating activities which were highly efficient in removing turbidity and chemical oxygen demand (COD) from brewery wastewater, diary wastewater and river water. The bioflocculants from the consortia seemed better than traditional flocculants such as alum . The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE and Bacillus sp. MAYA showed that this extracellular bioflocculant, composed of 66percent uronic acid and 31percent protein and an optimum flocculation (90 percent) of kaolin suspension, when the dosage concentration was 0.8 mg/ml, under weak alkaline pH of 8, and Ca2+ as a coagulant aid. The bioflocculant is thermally stable, with a high residual flocculating activity of 86.7 percent, 89.3 percent and 87.0 percent after heating at 50 oC, 80 oC and 100 oC for 25 min respectively. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl functional groups. Scanning electron microscopy (SEM) image revealed a crystal-linear spongy-like bioflocculant structure and EDX analysis of the purified bioflocculant showed that the elemental composition in mass proportion of C,N,O,S and P was 6.67:6.23:37.55:0.38:4.42 (percent w/w). However, the characteristics of the bioflocculant produced by the consortium of Cobetia sp OAUIFE and Bacillus sp. Gilbert showed an optimum flocculation (90 percent) of kaolin suspension when the dosage concentration was 0.2 mg/ml, under neutral pH of 7, and Ca2+ as a coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl and carbonyl functional groups. Scanning electron microscopy (SEM) image revealed an amorphous morphology. On the other hand the bioflocculant produced by the consortium of Bacillus sp. MAYA and Bacillus sp. Gilbert showed similar characteristic with the bioflocculant from the consortium of Cobetia sp. OAUIFE and Bacillus sp. Gilbert except for Al3+ being the preferred coagulant aid. The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert showed an optimum flocculation (87 percent) of kaolin suspension when the dosage concentration was 1.0 mg/ml. Under strong alkaline pH of 12, flocculating activity reached (95 percent) when Al3+ was the coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl and phosphoryl functional groups. Scanning electron microscopy (SEM) image revealed a flaky amorphous morphological structure. Due to the excellent COD and turbidity removal efficiencies of the bioflocculants produced by the consortia, these make those attractive candidates for use in water and wastewater treatment. , Thesis (PhD) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
- Authors: Ugbenyen, Anthony Moses https://orcid.org/0000-0002-1381-3428
- Date: 2013
- Subjects: Water -- Purification -- Flocculation , Water quality management , Flocculation
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24454 , vital:62804
- Description: The bioflocculant-producing potentials of three marine bacteria isolated from the sediment samples of Algoa Bay in the Eastern Cape Province of South Africa were assessed. Analysis of the partial nucleotide sequence of the 16S rDNA of the bacteria revealed 99 percent, 99 percent, and 98 percent similarity to Cobetia sp. L222, Bacillus sp. A-5A, and Bacillus sp. HXG-C1 respectively and the sequence was deposited in GenBank as Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert (accession number JF799092, JF799093, and HQ537128 respectively). Cultivation condition studies for Cobetia sp. OAUIFE revealed that bioflocculant production was optimal with an inoculum size of 2 percent (v/v), initial pH of 6.0, Mn2+ as the metal ion, and glucose as the carbon source. Metal ions, including Na+, K+, Li+, Ca2+and Mg2+ stimulated bioflocculant production resulting in flocculating activity of above 90 percent. This crude bioflocculant is thermally stable, with about 78 percent of its flocculating activity remaining after heating at 100 oC for 25 min. Analysis of the purified bioflocculant revealed it to be an acidic extracellular polysaccharide. FTIR analysis revealed the presence of methoxyl, hydroxyl, and carboxyl - groups in the compound bioflocculant and SEM micrograph of the bioflocculant revealed a crystal-linear structure. On the other hand, bioflocculant production by Bacillus sp. MAYA was optimal when glucose (95.6 percent flocculating activity) and ammonium nitrate (83.3 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 2 percent (v/v); initial pH 6; and Ca2+ as coagulant aid. Chemical analysis of the purified bioflocculant shows that it is composed of uronic acid, neutral sugar and protein. FTIR analysis also revealed the presence of methoxyl, hydroxyl, carboxyl and amino- groups in this bioflocculant. The bioflocculant is thermostable with about 65.6 percent residual flocculating activity retained after heating the bioflocculant at 100 oC for 25 min. However bioflocculant production by Bacillus sp. Gilbert was optimal when sodium carbonate (95.2 percent flocculating activity) and potassium nitrate (76.6 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 3 percent (v/v); initial pH 9; and Al3+ as cation. The crude bioflocculant retained 44.2 percent residual flocculating activity after heating at 100 oC for 15 min. FTIR analysis reveals the presence of hydroxyl, carboxyl and methylene - groups in the compound bioflocculant. SEM micrograph of the bioflocculant revealed an amorphous compound. The consortia of these bacteria strains also produced bioflocculants with high flocculating activities which were highly efficient in removing turbidity and chemical oxygen demand (COD) from brewery wastewater, diary wastewater and river water. The bioflocculants from the consortia seemed better than traditional flocculants such as alum . The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE and Bacillus sp. MAYA showed that this extracellular bioflocculant, composed of 66percent uronic acid and 31percent protein and an optimum flocculation (90 percent) of kaolin suspension, when the dosage concentration was 0.8 mg/ml, under weak alkaline pH of 8, and Ca2+ as a coagulant aid. The bioflocculant is thermally stable, with a high residual flocculating activity of 86.7 percent, 89.3 percent and 87.0 percent after heating at 50 oC, 80 oC and 100 oC for 25 min respectively. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl functional groups. Scanning electron microscopy (SEM) image revealed a crystal-linear spongy-like bioflocculant structure and EDX analysis of the purified bioflocculant showed that the elemental composition in mass proportion of C,N,O,S and P was 6.67:6.23:37.55:0.38:4.42 (percent w/w). However, the characteristics of the bioflocculant produced by the consortium of Cobetia sp OAUIFE and Bacillus sp. Gilbert showed an optimum flocculation (90 percent) of kaolin suspension when the dosage concentration was 0.2 mg/ml, under neutral pH of 7, and Ca2+ as a coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl and carbonyl functional groups. Scanning electron microscopy (SEM) image revealed an amorphous morphology. On the other hand the bioflocculant produced by the consortium of Bacillus sp. MAYA and Bacillus sp. Gilbert showed similar characteristic with the bioflocculant from the consortium of Cobetia sp. OAUIFE and Bacillus sp. Gilbert except for Al3+ being the preferred coagulant aid. The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert showed an optimum flocculation (87 percent) of kaolin suspension when the dosage concentration was 1.0 mg/ml. Under strong alkaline pH of 12, flocculating activity reached (95 percent) when Al3+ was the coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl and phosphoryl functional groups. Scanning electron microscopy (SEM) image revealed a flaky amorphous morphological structure. Due to the excellent COD and turbidity removal efficiencies of the bioflocculants produced by the consortia, these make those attractive candidates for use in water and wastewater treatment. , Thesis (PhD) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
Aspects of the ecology of the estuarine round-herring Gilchristella aestuaria (Pisces: Clupeidae) and its small-scale fishery potential
- Zvavahera, Munetsi https://orcid.org/0000-0002-5337-1943
- Authors: Zvavahera, Munetsi https://orcid.org/0000-0002-5337-1943
- Date: 2021-05
- Subjects: Small-scale fisheries , Silversides
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22765 , vital:52752
- Description: In the past two decades, there has been increasing pressure for small-scale inland fisheries to play a central role in food and nutrient security for poor communities in South Africa. For decades, South African inland fisheries have focussed on the exploitation of large fish species and generally ignored the exploitation of inland small fish species (SFS). This research aimed to assess the ecology and small-scale fishery potential of the estuarine round-herring, Gilchristella aestuaria. To understand the ecology of G. aestuaria better, morphometric trait analysis and fish condition of populations in relation to environmental variables (salinity, pH, temperature, turbidity and chlorophyll-a) were done. Fish were supplemented with samples acquired from the SAIAB collection facility for 14 sites to cover all the three South African biogeographic regions, stretching from Lake Sibaya (KZN) to the Orange River estuary in the western parts of the country. The morphometric trait analysis showed that G. aestuaria populations can be distinguished based on the trait variation, however there were many overlaps for populations that are interconnected, with distant/ geographically separated populations showing clear differences. Morphometric traits of the G. aestuaria population were significantly different, however there was no strong directional relationship with environmental variables and variation in morphometric traits. However, fish condition as measured by Fulton’s condition (K) and relative weight (Wr) showed variation between populations found in different environments. These differences suggest that these populations must be managed differently if G. aestuaria is to be exploited in managed fisheries. To determine the potential nutrient value of G. aestuaria to the human diet, samples from two freshwater sites and five estuarine sites were analysed for essential macro and micronutrients. The nutrient content of G. aestuaria revealed there is potential for exploitation, as the species has a high macro (protein and fat) and micronutrient composition (calcium, iron and zinc). Mean ± SD of selected nutrients were protein (61.7±5.0 g/100g), fat (20.4±3.7g/ 100g), calcium (3507.5±314.0mg), iron (40.37±14.0mg/ 100g), zinc (22.47±5.6mg/ 100) and vitamin A (37.3±44.4 RAE/ 100g). The nutrient composition of fish collected from freshwater sites was comparable to those collected from estuarine environments. Using the recommended dietary allowances (RDA) from literature, the mass of fish and the number of fish that would provide a minimum amount for each nutrient were calculated. A child would require only 13.4g of dry G. aestuaria or approximately 74 dried fish to meet the daily requirements of zinc. Other minerals such as iron and calcium also showed a similar low weight or number of fish required to meet daily requirements for the different categories. A small number of G. aestuaria are needed to meet RDA for groups (children, adult men, adult women, pregnant women and lactating mothers). A comparison was done for the nutrient composition of G. aestuaria with reference species that are already harvested for human consumption in some African and Asian countries. The protein content of G. aestuaria was comparable to Chisense (Microthrissa moeruensis) and Kapenta Limnothrissa miodon), while the fat composition was more than twice Chisense and Kapenta. Comparing the mineral composition, G. aestuaria had more than three times higher calcium than Mola (Amblypharyngodon mola) and Puti (Puntius sophore). Zinc composition was four times higher than M. moeruensis and L. miodon. Further exploration of the ecology of G. aestuaria was studied using the Sundays River irrigations ponds as a case study that would represent small impoundments across South Africa. Species rank abundance curve and catch per unit effort (CPUE) on the Sundays Irrigation ponds revealed that G. aestuaria dominated numerically and biomass in the Sundays River irrigation ponds. To assess the potential of harvesting G. aestuaria harvesting experiments were conducted using depletion (removal) sampling. Catchweight (kg) ranged from 2.16 (1.03; 3.28) to 61.25 (44.40; 78.09) kg and the estimated biomass from the depletion model ranged from 1.05 to 40.19 kg/ha for September 2019. The depletion model revealed that small impoundments have high biomass per hectare of G. aestuaria ranging from which indicates that the species may not support a commercial fishery but small-scale fisheries. In conclusion, G. aestuaria could become a meaningful contribution to the food and nutrient security of poor communities where available as a food source through small-scale fishery exploitation. The extent of this contribution may depend on its production potential in various regions and environments. More research is however needed to determine the long-term sustainability of harvesting of G aestuaria by looking at how populations respond to harvesting. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-05
- Authors: Zvavahera, Munetsi https://orcid.org/0000-0002-5337-1943
- Date: 2021-05
- Subjects: Small-scale fisheries , Silversides
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22765 , vital:52752
- Description: In the past two decades, there has been increasing pressure for small-scale inland fisheries to play a central role in food and nutrient security for poor communities in South Africa. For decades, South African inland fisheries have focussed on the exploitation of large fish species and generally ignored the exploitation of inland small fish species (SFS). This research aimed to assess the ecology and small-scale fishery potential of the estuarine round-herring, Gilchristella aestuaria. To understand the ecology of G. aestuaria better, morphometric trait analysis and fish condition of populations in relation to environmental variables (salinity, pH, temperature, turbidity and chlorophyll-a) were done. Fish were supplemented with samples acquired from the SAIAB collection facility for 14 sites to cover all the three South African biogeographic regions, stretching from Lake Sibaya (KZN) to the Orange River estuary in the western parts of the country. The morphometric trait analysis showed that G. aestuaria populations can be distinguished based on the trait variation, however there were many overlaps for populations that are interconnected, with distant/ geographically separated populations showing clear differences. Morphometric traits of the G. aestuaria population were significantly different, however there was no strong directional relationship with environmental variables and variation in morphometric traits. However, fish condition as measured by Fulton’s condition (K) and relative weight (Wr) showed variation between populations found in different environments. These differences suggest that these populations must be managed differently if G. aestuaria is to be exploited in managed fisheries. To determine the potential nutrient value of G. aestuaria to the human diet, samples from two freshwater sites and five estuarine sites were analysed for essential macro and micronutrients. The nutrient content of G. aestuaria revealed there is potential for exploitation, as the species has a high macro (protein and fat) and micronutrient composition (calcium, iron and zinc). Mean ± SD of selected nutrients were protein (61.7±5.0 g/100g), fat (20.4±3.7g/ 100g), calcium (3507.5±314.0mg), iron (40.37±14.0mg/ 100g), zinc (22.47±5.6mg/ 100) and vitamin A (37.3±44.4 RAE/ 100g). The nutrient composition of fish collected from freshwater sites was comparable to those collected from estuarine environments. Using the recommended dietary allowances (RDA) from literature, the mass of fish and the number of fish that would provide a minimum amount for each nutrient were calculated. A child would require only 13.4g of dry G. aestuaria or approximately 74 dried fish to meet the daily requirements of zinc. Other minerals such as iron and calcium also showed a similar low weight or number of fish required to meet daily requirements for the different categories. A small number of G. aestuaria are needed to meet RDA for groups (children, adult men, adult women, pregnant women and lactating mothers). A comparison was done for the nutrient composition of G. aestuaria with reference species that are already harvested for human consumption in some African and Asian countries. The protein content of G. aestuaria was comparable to Chisense (Microthrissa moeruensis) and Kapenta Limnothrissa miodon), while the fat composition was more than twice Chisense and Kapenta. Comparing the mineral composition, G. aestuaria had more than three times higher calcium than Mola (Amblypharyngodon mola) and Puti (Puntius sophore). Zinc composition was four times higher than M. moeruensis and L. miodon. Further exploration of the ecology of G. aestuaria was studied using the Sundays River irrigations ponds as a case study that would represent small impoundments across South Africa. Species rank abundance curve and catch per unit effort (CPUE) on the Sundays Irrigation ponds revealed that G. aestuaria dominated numerically and biomass in the Sundays River irrigation ponds. To assess the potential of harvesting G. aestuaria harvesting experiments were conducted using depletion (removal) sampling. Catchweight (kg) ranged from 2.16 (1.03; 3.28) to 61.25 (44.40; 78.09) kg and the estimated biomass from the depletion model ranged from 1.05 to 40.19 kg/ha for September 2019. The depletion model revealed that small impoundments have high biomass per hectare of G. aestuaria ranging from which indicates that the species may not support a commercial fishery but small-scale fisheries. In conclusion, G. aestuaria could become a meaningful contribution to the food and nutrient security of poor communities where available as a food source through small-scale fishery exploitation. The extent of this contribution may depend on its production potential in various regions and environments. More research is however needed to determine the long-term sustainability of harvesting of G aestuaria by looking at how populations respond to harvesting. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-05
Medicinal properties of Moringa (Moringa Oleifera Lam) leaves and the effect of its use as a supplement on goat growth performance and meat characteristics
- Moyo, Busani https://orcid.org/0000-0001-7002-7266
- Authors: Moyo, Busani https://orcid.org/0000-0001-7002-7266
- Date: 2011-09
- Subjects: Moringa , Medicinal plants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24376 , vital:62662
- Description: The main objective of the study was to determine if feeding goats with Moringa oleifera leaves would lead to an increase in productivity and in value of the meat. The proximate, van Soet, atomic absorption spectrophotometric and soxhlet extraction methods were used to determine the nutritional value M. oleifera leaves of the South African. The in-vitro antimicrobial screening methods were used to determine antimicrobial activities M. oleifera extracts while in vitro and invivo models were used to determine the antioxidant activities of M. oleifera leaves. An evaluation of the potential of M. oleifera leaf meal as a feed supplement in terms of its effect on helminth load, goat growth performance, carcass characteristics, meat quality attributes, nutritional and consumer sensory characteristics of goat meat was done. A total of 24, eight month old goats were randomly allocated to dietary treatments of M. oleifera leaf meal (MOL), sunflower seed cake (SC) and GH (grass hay) which was the control. All the groups were fed on basal diet of grass hay ad libitum and 200g wheat bran per head per day. The MOL group was given an additional 200 g of dried M. oleifera leaves while the SC group was offered 170 g sunflower seed cake per head/day. The study showed that the dried leaves had crude protein levels of 30.3 percent, polyunsaturated fatty acids (52.21 percent), Saturated fatty acids (43.31), n-3 (44.57 percent), n-6 (7.64 percent), 19 amino acids, vitamin E (77 mg/100 g) and Beta-carotene (18.5 mg/100 g). The M. oleifera leaf extracts showed antibacterial activities against Escherichia coli, Enterobacter cloace, Proteus vulgaris, Staphylococcus aureus and Micrococcus kristinae. The supplementation of goats with MOL and SC resulted in decreased feacal larval count and lower Haemonchus contortus, Trichostrongylus colubriforms and Oesophagastum columbianum worm burdens than those in the non-supplemented goats. Goats supplemented with SC and MOL had higher average daily weight gain and heavier carcasses than those in the GH group. Higher pH1 scores were observed in chevon from GH diet than the supplemented ones. The MOL and SC supplemented goats had chevon with higher values for lightness (L*) 24 hr post-mortem than the one from the GH group. The redness (a*) values of chevon 24 hr post mortem was highest in MOL supplemented goats. Warner Bratzler shear force (WBSF) values of SC (30.1 N) and MOL (29.8 N) supplemented goats were lower than those from GH diet (32.6 N). Chevon from goats fed GH diet had significantly higher cooking losses (29.5 percent) than that from MOL (25.4 percent) and SC (25.6 percent) fed groups. It was observed that chevon from MOL and SC supplemented groups had higher crude protein (23.57 and 22.95 percent, respectively) than the one from the GH group (21.20 percent). Cholesterol levels were higher in chevon from SC (42.84) supplemented goats than those from MOL (38.76) and GH (35.63 mg). Chevon from GH and MOL group had higher (P < 0.05) proportions of PUFA, n-3, PUFA/SFA ratio and lower n-6/n-3 ratio. Mean consumer scores for first bite, aroma, flavour and juiceness were higher in the MOL group than in the GH group (P < 0.05). The acetone extract exhibited higher concentrations of total flavonoids, flavonols, phenolics. The acetone extracts depicted higher percentage inhibition against DPPH, ABTS and nitric oxide radicals which were comparable with reference antioxidant (vitamin C and BHT). The M. oleifera leaf meal increased the antioxidant activity of GSH, SOD and catalase. Moringa oleifera leaves also exhibited medicinal properties by having anthelmintic, antibacterial activities and showed antioxidant properties. It was also observed that protein supplementation improved the animal growth performance, the physico-chemical characteristics, nutritional and fatty acids composition of meat hence meeting the consumer needs. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-09
- Authors: Moyo, Busani https://orcid.org/0000-0001-7002-7266
- Date: 2011-09
- Subjects: Moringa , Medicinal plants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24376 , vital:62662
- Description: The main objective of the study was to determine if feeding goats with Moringa oleifera leaves would lead to an increase in productivity and in value of the meat. The proximate, van Soet, atomic absorption spectrophotometric and soxhlet extraction methods were used to determine the nutritional value M. oleifera leaves of the South African. The in-vitro antimicrobial screening methods were used to determine antimicrobial activities M. oleifera extracts while in vitro and invivo models were used to determine the antioxidant activities of M. oleifera leaves. An evaluation of the potential of M. oleifera leaf meal as a feed supplement in terms of its effect on helminth load, goat growth performance, carcass characteristics, meat quality attributes, nutritional and consumer sensory characteristics of goat meat was done. A total of 24, eight month old goats were randomly allocated to dietary treatments of M. oleifera leaf meal (MOL), sunflower seed cake (SC) and GH (grass hay) which was the control. All the groups were fed on basal diet of grass hay ad libitum and 200g wheat bran per head per day. The MOL group was given an additional 200 g of dried M. oleifera leaves while the SC group was offered 170 g sunflower seed cake per head/day. The study showed that the dried leaves had crude protein levels of 30.3 percent, polyunsaturated fatty acids (52.21 percent), Saturated fatty acids (43.31), n-3 (44.57 percent), n-6 (7.64 percent), 19 amino acids, vitamin E (77 mg/100 g) and Beta-carotene (18.5 mg/100 g). The M. oleifera leaf extracts showed antibacterial activities against Escherichia coli, Enterobacter cloace, Proteus vulgaris, Staphylococcus aureus and Micrococcus kristinae. The supplementation of goats with MOL and SC resulted in decreased feacal larval count and lower Haemonchus contortus, Trichostrongylus colubriforms and Oesophagastum columbianum worm burdens than those in the non-supplemented goats. Goats supplemented with SC and MOL had higher average daily weight gain and heavier carcasses than those in the GH group. Higher pH1 scores were observed in chevon from GH diet than the supplemented ones. The MOL and SC supplemented goats had chevon with higher values for lightness (L*) 24 hr post-mortem than the one from the GH group. The redness (a*) values of chevon 24 hr post mortem was highest in MOL supplemented goats. Warner Bratzler shear force (WBSF) values of SC (30.1 N) and MOL (29.8 N) supplemented goats were lower than those from GH diet (32.6 N). Chevon from goats fed GH diet had significantly higher cooking losses (29.5 percent) than that from MOL (25.4 percent) and SC (25.6 percent) fed groups. It was observed that chevon from MOL and SC supplemented groups had higher crude protein (23.57 and 22.95 percent, respectively) than the one from the GH group (21.20 percent). Cholesterol levels were higher in chevon from SC (42.84) supplemented goats than those from MOL (38.76) and GH (35.63 mg). Chevon from GH and MOL group had higher (P < 0.05) proportions of PUFA, n-3, PUFA/SFA ratio and lower n-6/n-3 ratio. Mean consumer scores for first bite, aroma, flavour and juiceness were higher in the MOL group than in the GH group (P < 0.05). The acetone extract exhibited higher concentrations of total flavonoids, flavonols, phenolics. The acetone extracts depicted higher percentage inhibition against DPPH, ABTS and nitric oxide radicals which were comparable with reference antioxidant (vitamin C and BHT). The M. oleifera leaf meal increased the antioxidant activity of GSH, SOD and catalase. Moringa oleifera leaves also exhibited medicinal properties by having anthelmintic, antibacterial activities and showed antioxidant properties. It was also observed that protein supplementation improved the animal growth performance, the physico-chemical characteristics, nutritional and fatty acids composition of meat hence meeting the consumer needs. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-09
Comparative performance of 3-kWp ranges Solar Photovoltaic Systems under varying meteorological conditions in Alice, Eastern Cape Province, South Africa
- Apeh, Oliver Okechukwu https://orcid.org/0000-0003-4076-0613
- Authors: Apeh, Oliver Okechukwu https://orcid.org/0000-0003-4076-0613
- Date: 2021-08
- Subjects: Photovoltaic power systems , Solar energy
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21567 , vital:48888
- Description: PVsystem has recently emerged in South Africa as a way to curb the country’s persistent shortage of electricity. A wide effort for the past few decades have targeted at study, testing and demonstration of PV power systems which was established all over the country as an appropriate measure to tackle transportation, agriculture, industry, commercial as well as domestic activities. In view of these drives, both off-grid and grid-connected PV systems are being applied. However, operating a building with an off-grid system is one of the means to providing the possibility of energy access to places far away from the national grid. As an off-grid choice, 50 W SHS is being distributed to customers in distant rustic parts of the country where grid option is difficult to access. But the SHS of the stated capacity can barely generate 0.3 to 0.4 kWh of electric energy per day, even at the optimal solar radiations. In view of this, more efforts are directed at expanding the off-grid systems to accommodate large rural households in South Africa. This thesis is dedicated to a study on the various configurations and components of PV power plant as a way to enhance electricity generations in South Africa. To this effect, different power plants were considered at SolarWatt park, University of Fort Hare with the aim to conduct a comparative analysis of the charge controllers with respect to the charge and discharge rates of their respective batteries. The grid-connected PV power generation was classified into hybrid PV and grid-assisted PV, while off-grid is a BIPV. These power plants generations were installed for the purpose of research level with a total capacity of 11.4 kW. The off-grid system is made up of HIT modules, FlexMax80 charge controller, Victron energy inverter and M-Molar battery bank. The hybrid and grid-assisted systems each consist of 15 polycrystalline modules and Microcare charge controllers. In addition, hybrid comprises SMA Sunny Island inverter and Trojan battery bank whereas grid-assisted consist of Microcare inverter and Hoppercke battery bank. The first part of the experimental work was monitored, and the meteorological parameters which are ambient temperature, solar radiation, relative humidity and wind speed, were measured and evaluated while electrical parameters includes PV current and voltage, MPPT current and voltage, battery current and voltage and inverter current and voltage were also measured and evaluated in the second part of the experiment. This lasted for a period of four years, starting from 1st January 2017 to 31st December 2020. Similarly, the second aspect was to monitor the electrical performance of the three systems and was performed for a period of six months, starting from January to June 2019. During the second experiment, hybrid and grid-assisted systems were reconfigured to function as off-grid systems. Moreover, a detailed data acquisition system designed to measure and record both meteorological and electrical parameters affecting the performance of the systems. The electrical parameters include PV current and voltage, MPPT current, battery current and voltage and inverter current and voltage. Other parameters in the measurements are; inverter efficiency, active and apparent power, while meteorological parameters include; solar irradiance, ambient temperature, relative humidity, wind speed and direction. The meteorological results show that the maximum and minimum mean amount of global solar radiation was 7.34 kWh/m2/day in December and 3.03 kWh/m2/day in June, respectively, while the average radiation and temperature for the typical year were 4.98 kWh/m2/day and 16.88 oC respectively. The solar radiations obtained are within the range in major places in South Africa. Similarly, an average wind speed of 2.5 m/s is experienced in Alice in a year and average solar radiation of 606.06 W/m2 in summer and 346.17 W/m2 in winter. The three lead-acid battery systems monitored under the electrical aspect are M-Molar, Trojan and Hoppecke battery systems. It was established that the charging current decreases gradually from 27.7 to 18.5 A for the M-Molar while Hoppecke and Trojan deceased respectively from 15 to 10 A and 23 to 13 A at the end of each phase by charging it at the maximum power point of the PV array. It was equally found that the M-Molar battery current has the highest rate of charging and quickest rate of discharging in comparison to the other two batteries. Finally, from the results gotten from this research, we may propose that the solar PV system contributes significantly to the satisfaction of the needed electricity in South Africa. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-08
- Authors: Apeh, Oliver Okechukwu https://orcid.org/0000-0003-4076-0613
- Date: 2021-08
- Subjects: Photovoltaic power systems , Solar energy
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21567 , vital:48888
- Description: PVsystem has recently emerged in South Africa as a way to curb the country’s persistent shortage of electricity. A wide effort for the past few decades have targeted at study, testing and demonstration of PV power systems which was established all over the country as an appropriate measure to tackle transportation, agriculture, industry, commercial as well as domestic activities. In view of these drives, both off-grid and grid-connected PV systems are being applied. However, operating a building with an off-grid system is one of the means to providing the possibility of energy access to places far away from the national grid. As an off-grid choice, 50 W SHS is being distributed to customers in distant rustic parts of the country where grid option is difficult to access. But the SHS of the stated capacity can barely generate 0.3 to 0.4 kWh of electric energy per day, even at the optimal solar radiations. In view of this, more efforts are directed at expanding the off-grid systems to accommodate large rural households in South Africa. This thesis is dedicated to a study on the various configurations and components of PV power plant as a way to enhance electricity generations in South Africa. To this effect, different power plants were considered at SolarWatt park, University of Fort Hare with the aim to conduct a comparative analysis of the charge controllers with respect to the charge and discharge rates of their respective batteries. The grid-connected PV power generation was classified into hybrid PV and grid-assisted PV, while off-grid is a BIPV. These power plants generations were installed for the purpose of research level with a total capacity of 11.4 kW. The off-grid system is made up of HIT modules, FlexMax80 charge controller, Victron energy inverter and M-Molar battery bank. The hybrid and grid-assisted systems each consist of 15 polycrystalline modules and Microcare charge controllers. In addition, hybrid comprises SMA Sunny Island inverter and Trojan battery bank whereas grid-assisted consist of Microcare inverter and Hoppercke battery bank. The first part of the experimental work was monitored, and the meteorological parameters which are ambient temperature, solar radiation, relative humidity and wind speed, were measured and evaluated while electrical parameters includes PV current and voltage, MPPT current and voltage, battery current and voltage and inverter current and voltage were also measured and evaluated in the second part of the experiment. This lasted for a period of four years, starting from 1st January 2017 to 31st December 2020. Similarly, the second aspect was to monitor the electrical performance of the three systems and was performed for a period of six months, starting from January to June 2019. During the second experiment, hybrid and grid-assisted systems were reconfigured to function as off-grid systems. Moreover, a detailed data acquisition system designed to measure and record both meteorological and electrical parameters affecting the performance of the systems. The electrical parameters include PV current and voltage, MPPT current, battery current and voltage and inverter current and voltage. Other parameters in the measurements are; inverter efficiency, active and apparent power, while meteorological parameters include; solar irradiance, ambient temperature, relative humidity, wind speed and direction. The meteorological results show that the maximum and minimum mean amount of global solar radiation was 7.34 kWh/m2/day in December and 3.03 kWh/m2/day in June, respectively, while the average radiation and temperature for the typical year were 4.98 kWh/m2/day and 16.88 oC respectively. The solar radiations obtained are within the range in major places in South Africa. Similarly, an average wind speed of 2.5 m/s is experienced in Alice in a year and average solar radiation of 606.06 W/m2 in summer and 346.17 W/m2 in winter. The three lead-acid battery systems monitored under the electrical aspect are M-Molar, Trojan and Hoppecke battery systems. It was established that the charging current decreases gradually from 27.7 to 18.5 A for the M-Molar while Hoppecke and Trojan deceased respectively from 15 to 10 A and 23 to 13 A at the end of each phase by charging it at the maximum power point of the PV array. It was equally found that the M-Molar battery current has the highest rate of charging and quickest rate of discharging in comparison to the other two batteries. Finally, from the results gotten from this research, we may propose that the solar PV system contributes significantly to the satisfaction of the needed electricity in South Africa. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-08
Synthesis and in vitro biological studies of ursolic acid-based hybrid compounds
- Authors: Khwaza, Vuyolwethu
- Date: 2022
- Subjects: Herbal medicine , Herbs -- Therapeutic use , Antineoplastic antibiotics
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27797 , vital:69689
- Description: Ursolic acid UA, a pentacyclic triterpenoid that is commonly found in many medicinal herbs and fruits, has been identified as a potential source of therapeutic agents because of its potent biological effects, which include its potential anticancer and antimicrobial activities. However, its limited solubility, rapid metabolism and poor bioavailability inhibit its clinical applications. Numerous UA derivatives have been prepared over the past years in an effort to mitigate the drawbacks associated with UA, as new chemical entities for the treatment of various infections. There is very little progress in the discovery of efficient UA derivatives. In this study, a class of ester and amide-linked ursolic acid-based hybrid compounds fused with selected pharmaceutical scaffolds were successfully synthesized using amidation and esterification reactions and tested for antibacterial and cytotoxicity activities. Hybridizing UA with other known pharmaceutical scaffolds has the potential of overcoming its drawbacks. FT-IR, Mass Spectroscopy, and 1H13C-NMR spectroscopy were used to confirm the structures of the synthesized hybrid compounds. Among the tested ester-linked hybrid compounds in Chapter three, compounds 3.14-3.19,3.21, 3.34, 3.31, and 3.30 demonstrated significant antibacterial activities against some tested bacteria, with MIC values of 15.625 μgml. Furthermore, the in vitro cytotoxicity of these hybrids was determined using the MTT assay against three human tumor cell lines MCF7, MDA-MB-231, and HeLa cells. Compounds 3.19 and 3.34 were found to have better cytotoxic activity when compared to ursolic acid, with IC50 values of 46.99 and 48.18 μg ml respectively. Both compounds revealed more promising docking results, presenting favourable binding interactions as well as better docking energy against the MCF 7 protein target compared to the parent compound ursolic acid. In Chapter Four, among the tested amide-linked hybrid compounds, Compounds 4.17 and 4.24 demonstrated significant antibacterial activity against the majority of bacterial strains with MIC values of 15.625 gml. Compound 4.24 exhibited a MIC value of 15.625gmL against BS, SA, PV, KO, PM, and EC. Compound 4.23 was more cytotoxic to HeLa cells than ursolic acid. Furthermore, molecular docking calculations revealed that compound 4.16 strongly binds to the protein epidermal growth factor receptor while e compounds 4.17 and 4.24 showed a strong binding affinity for the methionyl-tRNA synthetase. In both cases, the hybrid compounds showed better conformational fittings in the active site of the targeted proteins as compared to the parent ursolic acid. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Khwaza, Vuyolwethu
- Date: 2022
- Subjects: Herbal medicine , Herbs -- Therapeutic use , Antineoplastic antibiotics
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27797 , vital:69689
- Description: Ursolic acid UA, a pentacyclic triterpenoid that is commonly found in many medicinal herbs and fruits, has been identified as a potential source of therapeutic agents because of its potent biological effects, which include its potential anticancer and antimicrobial activities. However, its limited solubility, rapid metabolism and poor bioavailability inhibit its clinical applications. Numerous UA derivatives have been prepared over the past years in an effort to mitigate the drawbacks associated with UA, as new chemical entities for the treatment of various infections. There is very little progress in the discovery of efficient UA derivatives. In this study, a class of ester and amide-linked ursolic acid-based hybrid compounds fused with selected pharmaceutical scaffolds were successfully synthesized using amidation and esterification reactions and tested for antibacterial and cytotoxicity activities. Hybridizing UA with other known pharmaceutical scaffolds has the potential of overcoming its drawbacks. FT-IR, Mass Spectroscopy, and 1H13C-NMR spectroscopy were used to confirm the structures of the synthesized hybrid compounds. Among the tested ester-linked hybrid compounds in Chapter three, compounds 3.14-3.19,3.21, 3.34, 3.31, and 3.30 demonstrated significant antibacterial activities against some tested bacteria, with MIC values of 15.625 μgml. Furthermore, the in vitro cytotoxicity of these hybrids was determined using the MTT assay against three human tumor cell lines MCF7, MDA-MB-231, and HeLa cells. Compounds 3.19 and 3.34 were found to have better cytotoxic activity when compared to ursolic acid, with IC50 values of 46.99 and 48.18 μg ml respectively. Both compounds revealed more promising docking results, presenting favourable binding interactions as well as better docking energy against the MCF 7 protein target compared to the parent compound ursolic acid. In Chapter Four, among the tested amide-linked hybrid compounds, Compounds 4.17 and 4.24 demonstrated significant antibacterial activity against the majority of bacterial strains with MIC values of 15.625 gml. Compound 4.24 exhibited a MIC value of 15.625gmL against BS, SA, PV, KO, PM, and EC. Compound 4.23 was more cytotoxic to HeLa cells than ursolic acid. Furthermore, molecular docking calculations revealed that compound 4.16 strongly binds to the protein epidermal growth factor receptor while e compounds 4.17 and 4.24 showed a strong binding affinity for the methionyl-tRNA synthetase. In both cases, the hybrid compounds showed better conformational fittings in the active site of the targeted proteins as compared to the parent ursolic acid. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
Effect of pomegranate (Punica granatum L) peel powder meal on growth performance, gut integrity, haemato-biochemical indices, meat, and bone quality of broiler chickens
- Akuru, Eunice Amaka https://orcid.org/0000-0002-3093-0247
- Authors: Akuru, Eunice Amaka https://orcid.org/0000-0002-3093-0247
- Date: 2022-04
- Subjects: Broilers (Chickens) , Meat -- Quality
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23611 , vital:58218
- Description: The objective of the current study was to investigate the overall response of broiler birds to varying dietary levels of pomegranate (Punica granatum L) peel powder meal (PPPM). A total of 432-day-old Cobb 500 broiler chicks were randomly divided into six experimental groups of four replications with 18 birds per replicate in a completely randomized design (CRD). The birds were fed isonitrogenous and isocaloric experimental diets designated as: T1-control diet with 0percent additives (negative control; NEGCON); T2- control diet supplemented with α-tocopherol acetate at 200g per ton (positive control; POSCON): T3, T4, T5 and T6-control diet supplemented with 2, 4, 6 and 8g/kg PPPM (PPPM2, PPPM4, PPPM6, PPPM8). The phytochemical, nutritional and antioxidant properties of the pomegranate peel powder were determined. Results showed that the South African-grown pomegranate peel (“Wonderful” variety) had rich protein and trace mineral contents. Higher (p < 0.05) antioxidant and hepatic anti-lipid peroxidative activities were recorded in the ethanol and acetone extracts than the water extract, whereas the three extracts had no toxic effects on liver and kidney cells (p > 0.05). The dietary effects of PPPM supplementation on growth performance, digestibility, carcass, and organ weight indices of Cobb 500 birds were determined. The POSCON diet enhanced (p < 0.05) feed conversion ratio (FCR) at week 3. The average final body weight and average daily weight gain were highest (p < 0.05) in birds fed PPPM2 and PPPM4 diets, whereas birds fed PPPM2 diet had enhanced (p < 0.05) FCR and protein efficiency ratio when compared with birds on POSCON. Thigh and breast weights were highest (p < 0.05) in birds on PPPM4 and PPPM8 diets, whereas birds fed PPPM4 diet had enhanced (p < 0.05) nutrient digestibility compared with those on POSCON. The antioxidant status and breast meat quality of Cobb 500 broiler birds fed diets supplemented with PPPM were determined. Meat from birds fed PPPM8 diet had the highest (p < 0.05) thawing loss, while cooking loss was lowest (p < 0.05) in the PPPM2 group. The highest (p < 0.05) ability to scavenge ABTS [(2, 2-azinobis (3ethylbenzothiazoline-6 sulfonic acid))] radical cation (ABTS+) was recorded in the PPPM2 and PPPM4 meat while PPPM8 meat had increased (p < 0.05) catalase activity. The fatty acid composition, oxidative status, and drip loss in breast meat of Cobb 500 broiler birds fed graded levels of PPPM was determined. Meat from birds fed PPPM4 diet had the lowest (p < 0.05) margaric (C17:0) and arachidic (C20:0) acids, while meat from birds fed PPPM8 diet had higher (p < 0.05) levels of eicosadenoic (C20:2, n-6) and arachidonic (AA, 20:4) acids. The POSCON had higher (p < 0.05) ability to reduce TBARS levels in meat on day-1 and day-16 of storage than the NEGCON and PPPM diets, whereas TBARS levels were lowest (p < 0.05) in PPPM6 meat on day-16. The gut pH, histology, haematology, serum-biochemical indices, and bone quality parameters of Cobb 500 broiler birds fed diets supplemented with PPPM was determined. Birds fed POSCON, PPM2 and PPPM4 diets had the lowest (p < 0.05) pH in the duodenum, jejunum, and caecum, whereas duodenal pH values were lowest (p < 0.05) in birds fed PPPM2 and PPPM4 diets compared with birds on NEGCON. Birds fed PPPM4 diet had the highest (p < 0.01) duodenal, jejunal and ileal villi height (VH), and the highest (p < 0.01) VH to crypt depth (CD) ratio in the duodenum, jejunum, and ileum. The lowest (p < 0.05) CD in the duodenum, jejunum and ileum was also recorded in birds fed PPPM4 diet. Birds fed PPPM8 diet had higher (p < 0.05) values for white blood cell count, red blood cell count, haemoglobin concentration and packed cell volume, whereas the lowest (p < 0.05) concentration of serum aspartate transaminase was recorded in birds fed PPPM4 diet. Birds on PPM4 diet had longer (p < 0.05) bones. Bone weight and bone breaking strength were highest (p < 0.05) in birds fed PPPM8 diet. Tibia zinc and iron concentrations increased as the inclusion levels of pomegranate peel powder meal increased. It was concluded that broiler birds require 4 g/kg pomegranate peel powder for enhanced growth performance, nutrient digestibility, gut histology, quality, and antioxidant enzyme activity of meat, whereas 8 g/kg pomegranate peel powder meal supplementation is required for enhanced heamato-biochemical indices, bone quality, fatty acid composition and lipid peroxidative parameters in broiler birds. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Akuru, Eunice Amaka https://orcid.org/0000-0002-3093-0247
- Date: 2022-04
- Subjects: Broilers (Chickens) , Meat -- Quality
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23611 , vital:58218
- Description: The objective of the current study was to investigate the overall response of broiler birds to varying dietary levels of pomegranate (Punica granatum L) peel powder meal (PPPM). A total of 432-day-old Cobb 500 broiler chicks were randomly divided into six experimental groups of four replications with 18 birds per replicate in a completely randomized design (CRD). The birds were fed isonitrogenous and isocaloric experimental diets designated as: T1-control diet with 0percent additives (negative control; NEGCON); T2- control diet supplemented with α-tocopherol acetate at 200g per ton (positive control; POSCON): T3, T4, T5 and T6-control diet supplemented with 2, 4, 6 and 8g/kg PPPM (PPPM2, PPPM4, PPPM6, PPPM8). The phytochemical, nutritional and antioxidant properties of the pomegranate peel powder were determined. Results showed that the South African-grown pomegranate peel (“Wonderful” variety) had rich protein and trace mineral contents. Higher (p < 0.05) antioxidant and hepatic anti-lipid peroxidative activities were recorded in the ethanol and acetone extracts than the water extract, whereas the three extracts had no toxic effects on liver and kidney cells (p > 0.05). The dietary effects of PPPM supplementation on growth performance, digestibility, carcass, and organ weight indices of Cobb 500 birds were determined. The POSCON diet enhanced (p < 0.05) feed conversion ratio (FCR) at week 3. The average final body weight and average daily weight gain were highest (p < 0.05) in birds fed PPPM2 and PPPM4 diets, whereas birds fed PPPM2 diet had enhanced (p < 0.05) FCR and protein efficiency ratio when compared with birds on POSCON. Thigh and breast weights were highest (p < 0.05) in birds on PPPM4 and PPPM8 diets, whereas birds fed PPPM4 diet had enhanced (p < 0.05) nutrient digestibility compared with those on POSCON. The antioxidant status and breast meat quality of Cobb 500 broiler birds fed diets supplemented with PPPM were determined. Meat from birds fed PPPM8 diet had the highest (p < 0.05) thawing loss, while cooking loss was lowest (p < 0.05) in the PPPM2 group. The highest (p < 0.05) ability to scavenge ABTS [(2, 2-azinobis (3ethylbenzothiazoline-6 sulfonic acid))] radical cation (ABTS+) was recorded in the PPPM2 and PPPM4 meat while PPPM8 meat had increased (p < 0.05) catalase activity. The fatty acid composition, oxidative status, and drip loss in breast meat of Cobb 500 broiler birds fed graded levels of PPPM was determined. Meat from birds fed PPPM4 diet had the lowest (p < 0.05) margaric (C17:0) and arachidic (C20:0) acids, while meat from birds fed PPPM8 diet had higher (p < 0.05) levels of eicosadenoic (C20:2, n-6) and arachidonic (AA, 20:4) acids. The POSCON had higher (p < 0.05) ability to reduce TBARS levels in meat on day-1 and day-16 of storage than the NEGCON and PPPM diets, whereas TBARS levels were lowest (p < 0.05) in PPPM6 meat on day-16. The gut pH, histology, haematology, serum-biochemical indices, and bone quality parameters of Cobb 500 broiler birds fed diets supplemented with PPPM was determined. Birds fed POSCON, PPM2 and PPPM4 diets had the lowest (p < 0.05) pH in the duodenum, jejunum, and caecum, whereas duodenal pH values were lowest (p < 0.05) in birds fed PPPM2 and PPPM4 diets compared with birds on NEGCON. Birds fed PPPM4 diet had the highest (p < 0.01) duodenal, jejunal and ileal villi height (VH), and the highest (p < 0.01) VH to crypt depth (CD) ratio in the duodenum, jejunum, and ileum. The lowest (p < 0.05) CD in the duodenum, jejunum and ileum was also recorded in birds fed PPPM4 diet. Birds fed PPPM8 diet had higher (p < 0.05) values for white blood cell count, red blood cell count, haemoglobin concentration and packed cell volume, whereas the lowest (p < 0.05) concentration of serum aspartate transaminase was recorded in birds fed PPPM4 diet. Birds on PPM4 diet had longer (p < 0.05) bones. Bone weight and bone breaking strength were highest (p < 0.05) in birds fed PPPM8 diet. Tibia zinc and iron concentrations increased as the inclusion levels of pomegranate peel powder meal increased. It was concluded that broiler birds require 4 g/kg pomegranate peel powder for enhanced growth performance, nutrient digestibility, gut histology, quality, and antioxidant enzyme activity of meat, whereas 8 g/kg pomegranate peel powder meal supplementation is required for enhanced heamato-biochemical indices, bone quality, fatty acid composition and lipid peroxidative parameters in broiler birds. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-04
Agro-morphological characterisation, nitrogen use efficiency and combining ability of quality protein maize (zea mays l.) genotypes for low nitrogen tolerance
- AdeOluwa, Olusola Oluyinka https://orcid.org/ 0000-0003-2145-7141
- Authors: AdeOluwa, Olusola Oluyinka https://orcid.org/ 0000-0003-2145-7141
- Date: 2021-08
- Subjects: Corn -- Quality
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21501 , vital:48855 , http://id.loc.gov/authorities/subjects/sh85032715
- Description: Low nitrogen stress tolerant Quality Protein Maize (QPM) genotypes will be of great benefit to farmers for increasing productivity in nitrogen depleted soils in the Eastern Cape (EC) Province, South Africa (SA). The current study evaluated: (i) QPM inbred lines for tolerance to low soil nitrogen, (ii) the Nitrogen Use Efficiency (NUE) of different QPM inbred lines, (iii) the combining ability of QPM genotypes for tolerance to low nitrogen, grain yield, and other agro-morphological traits, and (iv) the agro-morphological characteristics and adaptation of QPM hybrids to environments of different production potential in the Eastern Cape, South Africa. Thirty-two white-seeded QPM inbred lines obtained from CIMMYT-Zimbabwe and Quality Seeds (PTY) LTD were evaluated for tolerance to low soil nitrogen stress using two nitrogen (N) treatment levels: 0 kg N ha-1 and 30 kg N ha-1 under both glasshouse and field conditions at the Crop Research farm, University of Fort Hare, in two planting seasons. The study aimed at assessing the response of QPM inbred lines to low N, with a view to identifying low N tolerant types under both glasshouse and field conditions. Shoot length stress tolerance index (SHL STI) indicated lines L23, L29, L27, L13, L16, L17, L31, L14, L18 and L22 to be low soil N tolerant from the glasshouse study. From the field study, low N Stress Tolerance Index (STI) identified inbred lines L23, L31, L26, L28, L25, L29, L32, L4, L6, L3 and L2 as low soil N tolerant. These inbred lines also had high grain yields (GY) in the field under 0 kg N ha-1 (all ranked within the top ten except L2). They also had the potential for stable yields across environments considering their high Yield Stability Index (YSI), Mean Productivity (MP), Geometric Mean Productivity (GMP) and Stress Susceptibility Index (SSI) values. Both the glasshouse and field studies revealed inbred lines L22, L23, L26, L28, L25, L29 and L31 were common to both the glasshouse and field studies as being low soil N tolerant. These thirty-two parental QPM inbred lines were evaluated in the field for their nitrogen use efficiency (NUE) under five different nitrogen levels: 0, 30, 60, 90 and 120 kg N ha-1. The inbred lines studied under 0 kg N ha-1 and 30 kg N ha-1 indicated that N level expressed highly significant differences (P ≤ 0.001) for total nitrogen in biomass (Bio Total N), total nitrogen in grain (G Total N), grain yield (GY), nitrogen use efficiency (NUE) and almost all the indices estimated. The top six nutrient use efficient genotypes were L9, L14, L23, L25, L29 and L32 across N levels. However, the best and highest NUE was obtained from the lowest fertilizer dose, 30 kg N ha-1. Highly significant and positive correlation coefficients were found between Nitrogen Use Efficiency (NUE) and yield (+0.9), NUE and NUtE (+0.9), NUE and HI (Harvest Index) (+0.5), NUtE and yield (+0.99), HI and yield (+0.5) and NUtE and HI (+0.5). Thus, NUE, HI and NUtE could be good predictors of yield potential under low N soil conditions. Sixty-four testcross hybrids were generated from crossing these 32 QPM inbred lines with two QPM open pollinated varieties (OPVs) as testers in a line x tester design and were evaluated under 0 kg N ha-1 and 30 kg N ha-1 in the field. The objectives of the experiment were to: (i) identify high yielding hybrids with tolerance to low soil N in the EC; (ii) determine the combining abilities and mode of gene action for various traits under low and high nitrogen conditions; and (iii) group the inbred lines into heterotic groups for future use in the breeding program. Results revealed that under 30 kg N ha-1 (30N) condition, both additive and non-additive gene effects were observed with less importance of non-additive gene action for grain yield. Based on specific combining ability (SCA) effects, hybrids LNC22, LNC31, LOB22, LNC30, LNC29, LOB11, LNC18, LOB30, LOB19 and LNC24 showed outstanding performance under 0 kg N ha-1 (0N) condition with relatively acceptable SCA under 30N for yield. Inbred lines L6 (1.63), L22 (1.74), L29 (1.83) and L30 (1.24) showed positive and significant GCAs for grain yield under 0N. They were identified as the best combiners for grain yield as they were among the top ten performers for GCA under 0N. They can be very useful sources of low N tolerance genes. Two heterotic groups were formed under 0 kg N ha-1 and 30 kg N ha-1 conditions, and they will be useful for future hybrid development in the breeding program. Furthermore, these thirty-two QPM inbred lines were utilised as parental lines to generate seventy-six single cross hybrids. These single cross hybrids were evaluated across three environments of varying production potential in the Eastern Cape (EC), during the 2016/17 and 2017/18 summer seasons. Non-QPM hybrids namely PAN5Q649R and Phb31MO7BR, as well as QPM OPVs OBATANPA and Nelson's Choice were included in these preliminary variety trials (PVTs) as checks. Twenty-five hybrids expressing high values for the Smith – Hazel selection index were identified across sites over years. Among those hybrids were two checks, namely Q16 (PAN5Q649R) and Q33 (Phb31MO7BR). The top five high – yielding hybrids selected based on the selection index were considered to be the most productive, stable and adaptable based on the GGE biplot and AMMI stability values. None of these single cross hybrids over yielded the best hybrid check (Q16) in the current study. A high potential environment, Centane, was the ideal environments for evaluating genotypes in the present study. The studies showed inbred lines L22, L23, L26, L28, L25, L29 and L31 to be low N stress tolerant at 0 kg N ha-1 based on the low N stress tolerance indices under glasshouse and the field conditions; they were also among the top ten grain-yielders under field conditions at 0 kg N ha-1. Also, in the NUE study, they were found to be among the top ten most N-efficient inbred lines under low N soils, under 30 kg N ha-1, and were among the top twenty-four inbred lines with high NUE values across the N levels in the study. Inbred lines L29 and L22 also produced testcross hybrids that were among the top twenty based on GY under 0 kg N ha-1. The testcross hybrids produced from these inbred lines were also among the top twenty-five with outstanding SCA effects for GY. These inbred lines were also parental lines of some of the top twenty- five best hybrids selected based on the Smith – Hazel selection index in the PVT study. Inbred lines L22, L23, L26, L28, L25, L29 and L31 can therefore further be evaluated and used as sources of N-tolerance genes in QPM breeding programs. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-08
- Authors: AdeOluwa, Olusola Oluyinka https://orcid.org/ 0000-0003-2145-7141
- Date: 2021-08
- Subjects: Corn -- Quality
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21501 , vital:48855 , http://id.loc.gov/authorities/subjects/sh85032715
- Description: Low nitrogen stress tolerant Quality Protein Maize (QPM) genotypes will be of great benefit to farmers for increasing productivity in nitrogen depleted soils in the Eastern Cape (EC) Province, South Africa (SA). The current study evaluated: (i) QPM inbred lines for tolerance to low soil nitrogen, (ii) the Nitrogen Use Efficiency (NUE) of different QPM inbred lines, (iii) the combining ability of QPM genotypes for tolerance to low nitrogen, grain yield, and other agro-morphological traits, and (iv) the agro-morphological characteristics and adaptation of QPM hybrids to environments of different production potential in the Eastern Cape, South Africa. Thirty-two white-seeded QPM inbred lines obtained from CIMMYT-Zimbabwe and Quality Seeds (PTY) LTD were evaluated for tolerance to low soil nitrogen stress using two nitrogen (N) treatment levels: 0 kg N ha-1 and 30 kg N ha-1 under both glasshouse and field conditions at the Crop Research farm, University of Fort Hare, in two planting seasons. The study aimed at assessing the response of QPM inbred lines to low N, with a view to identifying low N tolerant types under both glasshouse and field conditions. Shoot length stress tolerance index (SHL STI) indicated lines L23, L29, L27, L13, L16, L17, L31, L14, L18 and L22 to be low soil N tolerant from the glasshouse study. From the field study, low N Stress Tolerance Index (STI) identified inbred lines L23, L31, L26, L28, L25, L29, L32, L4, L6, L3 and L2 as low soil N tolerant. These inbred lines also had high grain yields (GY) in the field under 0 kg N ha-1 (all ranked within the top ten except L2). They also had the potential for stable yields across environments considering their high Yield Stability Index (YSI), Mean Productivity (MP), Geometric Mean Productivity (GMP) and Stress Susceptibility Index (SSI) values. Both the glasshouse and field studies revealed inbred lines L22, L23, L26, L28, L25, L29 and L31 were common to both the glasshouse and field studies as being low soil N tolerant. These thirty-two parental QPM inbred lines were evaluated in the field for their nitrogen use efficiency (NUE) under five different nitrogen levels: 0, 30, 60, 90 and 120 kg N ha-1. The inbred lines studied under 0 kg N ha-1 and 30 kg N ha-1 indicated that N level expressed highly significant differences (P ≤ 0.001) for total nitrogen in biomass (Bio Total N), total nitrogen in grain (G Total N), grain yield (GY), nitrogen use efficiency (NUE) and almost all the indices estimated. The top six nutrient use efficient genotypes were L9, L14, L23, L25, L29 and L32 across N levels. However, the best and highest NUE was obtained from the lowest fertilizer dose, 30 kg N ha-1. Highly significant and positive correlation coefficients were found between Nitrogen Use Efficiency (NUE) and yield (+0.9), NUE and NUtE (+0.9), NUE and HI (Harvest Index) (+0.5), NUtE and yield (+0.99), HI and yield (+0.5) and NUtE and HI (+0.5). Thus, NUE, HI and NUtE could be good predictors of yield potential under low N soil conditions. Sixty-four testcross hybrids were generated from crossing these 32 QPM inbred lines with two QPM open pollinated varieties (OPVs) as testers in a line x tester design and were evaluated under 0 kg N ha-1 and 30 kg N ha-1 in the field. The objectives of the experiment were to: (i) identify high yielding hybrids with tolerance to low soil N in the EC; (ii) determine the combining abilities and mode of gene action for various traits under low and high nitrogen conditions; and (iii) group the inbred lines into heterotic groups for future use in the breeding program. Results revealed that under 30 kg N ha-1 (30N) condition, both additive and non-additive gene effects were observed with less importance of non-additive gene action for grain yield. Based on specific combining ability (SCA) effects, hybrids LNC22, LNC31, LOB22, LNC30, LNC29, LOB11, LNC18, LOB30, LOB19 and LNC24 showed outstanding performance under 0 kg N ha-1 (0N) condition with relatively acceptable SCA under 30N for yield. Inbred lines L6 (1.63), L22 (1.74), L29 (1.83) and L30 (1.24) showed positive and significant GCAs for grain yield under 0N. They were identified as the best combiners for grain yield as they were among the top ten performers for GCA under 0N. They can be very useful sources of low N tolerance genes. Two heterotic groups were formed under 0 kg N ha-1 and 30 kg N ha-1 conditions, and they will be useful for future hybrid development in the breeding program. Furthermore, these thirty-two QPM inbred lines were utilised as parental lines to generate seventy-six single cross hybrids. These single cross hybrids were evaluated across three environments of varying production potential in the Eastern Cape (EC), during the 2016/17 and 2017/18 summer seasons. Non-QPM hybrids namely PAN5Q649R and Phb31MO7BR, as well as QPM OPVs OBATANPA and Nelson's Choice were included in these preliminary variety trials (PVTs) as checks. Twenty-five hybrids expressing high values for the Smith – Hazel selection index were identified across sites over years. Among those hybrids were two checks, namely Q16 (PAN5Q649R) and Q33 (Phb31MO7BR). The top five high – yielding hybrids selected based on the selection index were considered to be the most productive, stable and adaptable based on the GGE biplot and AMMI stability values. None of these single cross hybrids over yielded the best hybrid check (Q16) in the current study. A high potential environment, Centane, was the ideal environments for evaluating genotypes in the present study. The studies showed inbred lines L22, L23, L26, L28, L25, L29 and L31 to be low N stress tolerant at 0 kg N ha-1 based on the low N stress tolerance indices under glasshouse and the field conditions; they were also among the top ten grain-yielders under field conditions at 0 kg N ha-1. Also, in the NUE study, they were found to be among the top ten most N-efficient inbred lines under low N soils, under 30 kg N ha-1, and were among the top twenty-four inbred lines with high NUE values across the N levels in the study. Inbred lines L29 and L22 also produced testcross hybrids that were among the top twenty based on GY under 0 kg N ha-1. The testcross hybrids produced from these inbred lines were also among the top twenty-five with outstanding SCA effects for GY. These inbred lines were also parental lines of some of the top twenty- five best hybrids selected based on the Smith – Hazel selection index in the PVT study. Inbred lines L22, L23, L26, L28, L25, L29 and L31 can therefore further be evaluated and used as sources of N-tolerance genes in QPM breeding programs. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-08
Viability of government funded broiler production : lessons from Northern KwaZulu Natal, South Africa
- Mdletshe, Sifiso Themba Clement https://orcid.org/0000-0002-2668-0193
- Authors: Mdletshe, Sifiso Themba Clement https://orcid.org/0000-0002-2668-0193
- Date: 2023-04
- Subjects: Broilers (Chickens) -- Economic aspects , Broilers (Poultry) , Broilers (Chickens) -- Breeding
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27843 , vital:69947
- Description: Generally, rural areas continue to experience high poverty levels and low incomes, which seem to be occasioned by high unemployment rates, limited educational attainments, and devastating floods and droughts. This situation is further exacerbated by increase in crime rates, making livelihoods even more difficult. To mitigate such adverse situations, rural households employ diverse strategies, including maintaining community gardens, one-home-one-garden schemes, as well as livestock and poultry production. The most prevalent livelihood strategy in South Africa or KwaZulu-Natal is broiler production, since it needs less space and a short production cycle compared to other livestock or crop enterprises. At the same time, income is generated over a short period. Besides, the government of KwaZulu Natal has actively intervened in the sector as part of its broader poverty reduction strategy and farmer support programmes. In KwaZulu-Natal Province, the provincial government has been supporting broiler producers for many years. While substantial research work has been done in the province on livelihood strategies, including livestock production on a province-wide basis, there is no information about how successful the broiler production funded by the government has being. Broader concerns about production problems have not been assuaged based on systematic studies and evidence. It is this wise that this study was initiated. The objective is to assess the economic viability of government-funded small-scale broiler projects in the KwaZulu-Natal Province of South Africa and determine the implications for poverty reduction and food security. Data were collected from the government-funded small-scale broiler producers that are residing in Northern KwaZulu-Natal districts uThungulu, Zululand and uMkhanyakude. A total of 75 small-scale broiler projects 25 broiler projects in each district were selected by probability sampling procedure for the interviews. Questionnaires that combined both close-ended and open-ended questions were used to collect primary data, which include production and marketing, as well as the factors that influence the profitability of the small-scale broiler projects. After collection, data were captured and encoded on spreadsheets in Microsoft Excel and exported to Statistical Package for the Social Science (SPSS) software version 26 and STATA for analyses. Descriptive statistics applied include frequencies and means. In addition, a gross margin (GM) and gross profit margin (GPM) analysis were employed to assess the profitability of government-funded small-scale broiler projects. Both profitability and gross margin analyses were used as proxies for farmers’ motivation and incentives to participate in broiler production. Further analyses were conducted to determine the model that best explains the underlying relationships. Initially, the Multiple Linear Regression Model was applied to determine the factors influencing the profitability of government-funded small-scale broiler projects. The indication was that while positive profits were revealed, the system seemed to fall short of its potential. In light of that, it was decided to fit another model to estimate the technical efficiency of the system and gain an understanding of the causes of any inefficiency that might exist in the production system. In that regard, the one-step Stochastic Frontier Model was employed to show that the technical efficiency of broiler production systems in the project area was positively and significantly influenced by flock size, the quantity of feeds and labour costs, while medication played no role possibly because of weak extension coverage. An inefficiency model fitted as part of the one-step model suggested that age, gender and educational level were significant influencers of technical inefficiency, with the possibility that the older the farmers, the more technically inefficient the system possibly because of the strenuousness of commercial poultry production. In addition, it was found that the more educated the farmer, the less inefficient the farm, which conversely means that the system becomes more efficient as the farmer receives more education. The negative coefficient of the gender variable also implies that for farms managed by female farmers, the system was less inefficient, which is more technically efficient, and this can be explained by women’s propensity to be more gentle, caring and sensitive in managing the chickens than their male counterparts. Heteroskedasticity tests and corrections were conducted in the one-step estimation technique to show that variations in the inefficiency term (μ) and the stochastic error term were explained by age and educational level for the most part. Clearly, improvements in the broiler industry in KwaZulu-Natal will depend to a large extent on the knowledge and experience of the farmers and substantial enlargement of the flock size of adequately fed birds. Attention to these elements is expected to have important practical implications for sustainable broiler poultry development and food security in the project area, as well as locations possessing identical features and characteristics. , Thesis (MSci) -- Faculty of Science and Agriculture, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Mdletshe, Sifiso Themba Clement https://orcid.org/0000-0002-2668-0193
- Date: 2023-04
- Subjects: Broilers (Chickens) -- Economic aspects , Broilers (Poultry) , Broilers (Chickens) -- Breeding
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27843 , vital:69947
- Description: Generally, rural areas continue to experience high poverty levels and low incomes, which seem to be occasioned by high unemployment rates, limited educational attainments, and devastating floods and droughts. This situation is further exacerbated by increase in crime rates, making livelihoods even more difficult. To mitigate such adverse situations, rural households employ diverse strategies, including maintaining community gardens, one-home-one-garden schemes, as well as livestock and poultry production. The most prevalent livelihood strategy in South Africa or KwaZulu-Natal is broiler production, since it needs less space and a short production cycle compared to other livestock or crop enterprises. At the same time, income is generated over a short period. Besides, the government of KwaZulu Natal has actively intervened in the sector as part of its broader poverty reduction strategy and farmer support programmes. In KwaZulu-Natal Province, the provincial government has been supporting broiler producers for many years. While substantial research work has been done in the province on livelihood strategies, including livestock production on a province-wide basis, there is no information about how successful the broiler production funded by the government has being. Broader concerns about production problems have not been assuaged based on systematic studies and evidence. It is this wise that this study was initiated. The objective is to assess the economic viability of government-funded small-scale broiler projects in the KwaZulu-Natal Province of South Africa and determine the implications for poverty reduction and food security. Data were collected from the government-funded small-scale broiler producers that are residing in Northern KwaZulu-Natal districts uThungulu, Zululand and uMkhanyakude. A total of 75 small-scale broiler projects 25 broiler projects in each district were selected by probability sampling procedure for the interviews. Questionnaires that combined both close-ended and open-ended questions were used to collect primary data, which include production and marketing, as well as the factors that influence the profitability of the small-scale broiler projects. After collection, data were captured and encoded on spreadsheets in Microsoft Excel and exported to Statistical Package for the Social Science (SPSS) software version 26 and STATA for analyses. Descriptive statistics applied include frequencies and means. In addition, a gross margin (GM) and gross profit margin (GPM) analysis were employed to assess the profitability of government-funded small-scale broiler projects. Both profitability and gross margin analyses were used as proxies for farmers’ motivation and incentives to participate in broiler production. Further analyses were conducted to determine the model that best explains the underlying relationships. Initially, the Multiple Linear Regression Model was applied to determine the factors influencing the profitability of government-funded small-scale broiler projects. The indication was that while positive profits were revealed, the system seemed to fall short of its potential. In light of that, it was decided to fit another model to estimate the technical efficiency of the system and gain an understanding of the causes of any inefficiency that might exist in the production system. In that regard, the one-step Stochastic Frontier Model was employed to show that the technical efficiency of broiler production systems in the project area was positively and significantly influenced by flock size, the quantity of feeds and labour costs, while medication played no role possibly because of weak extension coverage. An inefficiency model fitted as part of the one-step model suggested that age, gender and educational level were significant influencers of technical inefficiency, with the possibility that the older the farmers, the more technically inefficient the system possibly because of the strenuousness of commercial poultry production. In addition, it was found that the more educated the farmer, the less inefficient the farm, which conversely means that the system becomes more efficient as the farmer receives more education. The negative coefficient of the gender variable also implies that for farms managed by female farmers, the system was less inefficient, which is more technically efficient, and this can be explained by women’s propensity to be more gentle, caring and sensitive in managing the chickens than their male counterparts. Heteroskedasticity tests and corrections were conducted in the one-step estimation technique to show that variations in the inefficiency term (μ) and the stochastic error term were explained by age and educational level for the most part. Clearly, improvements in the broiler industry in KwaZulu-Natal will depend to a large extent on the knowledge and experience of the farmers and substantial enlargement of the flock size of adequately fed birds. Attention to these elements is expected to have important practical implications for sustainable broiler poultry development and food security in the project area, as well as locations possessing identical features and characteristics. , Thesis (MSci) -- Faculty of Science and Agriculture, 2023
- Full Text:
- Date Issued: 2023-04
Assessment of the human health implications of climate variability in East London, Eastern Cape, South Africa
- Orimoloye, Israel Ropo https://orcid.org/0000-0001-5058-2799
- Authors: Orimoloye, Israel Ropo https://orcid.org/0000-0001-5058-2799
- Date: 2018
- Subjects: Climatic changes http://id.loc.gov/authorities/subjects/sh85027037
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/19715 , vital:43171
- Description: Impacts associated with climate variability and extreme heat are already obvious in varying degrees and expected to be disruptive in the near future across the globe especially in the urban regions. Urban areas have distinctive features that leave their residents and properties vulnerable to extreme climate events. Global temperatures continue to change, reaching new levels almost every year for the past two decades. However, even though the causes are debated it is evident that climate variability is real. Climate variability and disaster risk are threats to human health that adversely reinforce each other. Better knowledge on the association between climate change, variability and extreme weather-related illness is needed and can aid strategies to reduce vulnerabilities. The impacts of climate variability on the health of residents in East London (EL) area in the Eastern Cape Province, South Africa were explored through four interdependent research segments. The first section examined the climate variability and urban surface thermal characteristics implication on human health using Remote Sensing (RS) and Geographic Information System (GIS) techniques. Remote sensing was used to assess the Land Surface Temperature (LST) and estimated Radiation (R) of East London area from Landsat Thematic Mapper (TM) images for 1986, 1996, 2006 as well as from Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) for 2016 spanning a period of 30 years. Rapid urbanization and land cover changes in this area have contributed significantly to this drastic change in the natural land surface characteristics (increased land surface temperature and surface solar radiation). For instance, vegetation cover declined by about 358.812km2 while built-up areas increased by 175.473km2 during this period which correlates with the area thermal characteristics changes. Radiation levels also increased over the years with values exceeding the global solar radiation index. Exposure to increased surface radiation poses risks of heat stroke, skin cancer and heart disease to the local population. Consequently, this study provides pertinent information on human health sustainability and epidemiological case management. The second part explored past temperature and humidity trends (1986-2016) and projects future trends (2017-2030). The historical data of meteorological variables were obtained from the archives of the South African Weather Service and analyzed using the ordinary least square regression model in GRETL (GNU Regression Econometric and Time-series Library) statistical software. This study discovered a local consistency between models and the observations add to existing knowledge and this is crucial in knowing the shifts in climatic change as well as recognizing variability and its conflicting effects on human health, environment, agriculture, ecological sustainability and socioeconomic status in the region. The third segment assessed the potential impacts of climate variability on health using existing heat indices during the study period. The results demonstrated that in East London from 1986 to 2016 during summer and autumn (December to May) of various years exceeded high heat index values. It is obvious that summer and autumn months are more vulnerable to heat extreme and humidex. The humidex and Heat Index (HI) increased annually by 0.03 percent and 0.9 percent respectively throughout the study period. The increment in the various indices showed highly significant ill-health and environmental impacts on humans especially with prolonged exposure. The last segment appraised the association between climatic elements and epidemiological incidences of the study area between 2012 and 2016. The epidemiology incidences data were obtained from the archives of the Cecilia Makiwane Hospital in East London area and National Tertiary Service Grant (NTSG) database for the period. The results have showed that there exists significant effects of climate variability on the health of East London residents and these have been identified to have negative impacts on health of the people in the area. This study also revealed noticeable impacts of extreme heat on human health and a positive correlation between meteorological components (HI and temperature) and epidemiological cases (cardiovascular, skin cancer and diarrhea) during the study period. , Thesis (PhD) (Geography) -- University of Fort Hare, 2018
- Full Text:
- Date Issued: 2018
- Authors: Orimoloye, Israel Ropo https://orcid.org/0000-0001-5058-2799
- Date: 2018
- Subjects: Climatic changes http://id.loc.gov/authorities/subjects/sh85027037
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/19715 , vital:43171
- Description: Impacts associated with climate variability and extreme heat are already obvious in varying degrees and expected to be disruptive in the near future across the globe especially in the urban regions. Urban areas have distinctive features that leave their residents and properties vulnerable to extreme climate events. Global temperatures continue to change, reaching new levels almost every year for the past two decades. However, even though the causes are debated it is evident that climate variability is real. Climate variability and disaster risk are threats to human health that adversely reinforce each other. Better knowledge on the association between climate change, variability and extreme weather-related illness is needed and can aid strategies to reduce vulnerabilities. The impacts of climate variability on the health of residents in East London (EL) area in the Eastern Cape Province, South Africa were explored through four interdependent research segments. The first section examined the climate variability and urban surface thermal characteristics implication on human health using Remote Sensing (RS) and Geographic Information System (GIS) techniques. Remote sensing was used to assess the Land Surface Temperature (LST) and estimated Radiation (R) of East London area from Landsat Thematic Mapper (TM) images for 1986, 1996, 2006 as well as from Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) for 2016 spanning a period of 30 years. Rapid urbanization and land cover changes in this area have contributed significantly to this drastic change in the natural land surface characteristics (increased land surface temperature and surface solar radiation). For instance, vegetation cover declined by about 358.812km2 while built-up areas increased by 175.473km2 during this period which correlates with the area thermal characteristics changes. Radiation levels also increased over the years with values exceeding the global solar radiation index. Exposure to increased surface radiation poses risks of heat stroke, skin cancer and heart disease to the local population. Consequently, this study provides pertinent information on human health sustainability and epidemiological case management. The second part explored past temperature and humidity trends (1986-2016) and projects future trends (2017-2030). The historical data of meteorological variables were obtained from the archives of the South African Weather Service and analyzed using the ordinary least square regression model in GRETL (GNU Regression Econometric and Time-series Library) statistical software. This study discovered a local consistency between models and the observations add to existing knowledge and this is crucial in knowing the shifts in climatic change as well as recognizing variability and its conflicting effects on human health, environment, agriculture, ecological sustainability and socioeconomic status in the region. The third segment assessed the potential impacts of climate variability on health using existing heat indices during the study period. The results demonstrated that in East London from 1986 to 2016 during summer and autumn (December to May) of various years exceeded high heat index values. It is obvious that summer and autumn months are more vulnerable to heat extreme and humidex. The humidex and Heat Index (HI) increased annually by 0.03 percent and 0.9 percent respectively throughout the study period. The increment in the various indices showed highly significant ill-health and environmental impacts on humans especially with prolonged exposure. The last segment appraised the association between climatic elements and epidemiological incidences of the study area between 2012 and 2016. The epidemiology incidences data were obtained from the archives of the Cecilia Makiwane Hospital in East London area and National Tertiary Service Grant (NTSG) database for the period. The results have showed that there exists significant effects of climate variability on the health of East London residents and these have been identified to have negative impacts on health of the people in the area. This study also revealed noticeable impacts of extreme heat on human health and a positive correlation between meteorological components (HI and temperature) and epidemiological cases (cardiovascular, skin cancer and diarrhea) during the study period. , Thesis (PhD) (Geography) -- University of Fort Hare, 2018
- Full Text:
- Date Issued: 2018
Study of the biotransformations and microbiological properties of cymbopogon citratus
- Ajayi, Emmanuel Olusegun https://orcid.org/0000-0002-0838-4948
- Authors: Ajayi, Emmanuel Olusegun https://orcid.org/0000-0002-0838-4948
- Date: 2015
- Subjects: Lemongras , Essences and essential oils
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/19737 , vital:43197
- Description: Variations in the essential oil yield, chemical composition and kinetics of chemical transformation, antibacterial, and antioxidant properties of the Cymbopogon citratus cultivated in Alice, Eastern Cape of South Africa, over a period of 12 months using the solvent-free microwave extraction and the modified forms of conventional hydrodistillation methods have been evaluated. The modified forms involve variation in the pH medium to effect extraction and to obtain the whole leaf extracts of Cymbopogon citratus (lemongrass). The GC-MS analyses of the essential oils revealed the presence of 10, 11, 13, and 9 principal compounds in the microwave, extraction, hydrodistillation (water-distilled), hydrodistillation (aciddistilled and hydrodistillation (base-distilled), respectively with citral being the prominent compound in all the various extraction methods, with the water-distilled method having the highest cumulative citral content under the period specified. Each of the components of the oils varied in quantity and quality of yield at different points of the year. Different extraction methods produce different compounds. Increase in the amount of citral content was observed during the maturation stage of Cymbopogon citratus in all the extraction methods. Quantitative evaluation of antibacterial activity, minimum inhibitory concentration (MIC) values were determined on the oils and extracts of Cymbopogon citratus using agar dilution method. The essential oils obtained using all the methods of extraction showed activity against all the tested bacteria at a concentration of 10 mg mL-1. The minimum inhibitory concentrations for the acid-distilled varied between 1.25 and 5.0 mg mL-1, while those obtained by both water- and base-distilled showed equal activity on the microorganisms with the MIC ranging between 2.5 and 10 mg mL-1. The microwave extraction showed the least activity with the MIC of 10 mg mL-1. This however suggested that the oils obtained through acid-distillation showed the greatest activity than all other methods of extraction. Activity of the various extracts on bacteria showed that the ethanol extract had the highest activity on the tested organisms with MIC ranging between 0.625 and 1.25 mg mL-1. This was closely followed by the acid-extract (1.25 and 5.0 mg mL-1), methanol extract (1.25 and 10 mg mL-1), acetone extract (2.5 and 5.0 mg mL-1), and base extract (5.0 mg mL-1). Both cold water and hot water extracts showed the least activity of MIC, >10 mg mL-1. The antioxidant and free-radical scavenging activity of the obtained oils and extracts were tested by means of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH+) assay, [(2,2ˊ-azino bis-(3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS), nitric oxide and ferric reducing power assays. The oils and extracts showed DPPH radical scavenging ability, but not as high as the standard drugs. The base extract showed a higher reducing power than the standard drug, rutin. There were significant differences in the phytochemicals contents of the various leaf extracts. The acetone extract has the highest flavonol, proanthocyanidin, and alkaloid contents. The ethanol extract showed the highest amount of phenolic content with the acid extract, having the least. Thin layer chromatography (TLC) and column chromatography was employed to obtain different fractions of extracts using four eluent solvent systems of varying polarities: toluene, petroleum ether, hexane and ethyl acetate and sprayed with anisaldehyde. A single, visible spot of B-fraction was developed, collected and analyzed as 1-methyl-2,4,5- trinitroimidazole with renown valuable properties. , Thesis (PhD) -- Faculty of Science and Agriculture, 2015
- Full Text:
- Date Issued: 2015
- Authors: Ajayi, Emmanuel Olusegun https://orcid.org/0000-0002-0838-4948
- Date: 2015
- Subjects: Lemongras , Essences and essential oils
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/19737 , vital:43197
- Description: Variations in the essential oil yield, chemical composition and kinetics of chemical transformation, antibacterial, and antioxidant properties of the Cymbopogon citratus cultivated in Alice, Eastern Cape of South Africa, over a period of 12 months using the solvent-free microwave extraction and the modified forms of conventional hydrodistillation methods have been evaluated. The modified forms involve variation in the pH medium to effect extraction and to obtain the whole leaf extracts of Cymbopogon citratus (lemongrass). The GC-MS analyses of the essential oils revealed the presence of 10, 11, 13, and 9 principal compounds in the microwave, extraction, hydrodistillation (water-distilled), hydrodistillation (aciddistilled and hydrodistillation (base-distilled), respectively with citral being the prominent compound in all the various extraction methods, with the water-distilled method having the highest cumulative citral content under the period specified. Each of the components of the oils varied in quantity and quality of yield at different points of the year. Different extraction methods produce different compounds. Increase in the amount of citral content was observed during the maturation stage of Cymbopogon citratus in all the extraction methods. Quantitative evaluation of antibacterial activity, minimum inhibitory concentration (MIC) values were determined on the oils and extracts of Cymbopogon citratus using agar dilution method. The essential oils obtained using all the methods of extraction showed activity against all the tested bacteria at a concentration of 10 mg mL-1. The minimum inhibitory concentrations for the acid-distilled varied between 1.25 and 5.0 mg mL-1, while those obtained by both water- and base-distilled showed equal activity on the microorganisms with the MIC ranging between 2.5 and 10 mg mL-1. The microwave extraction showed the least activity with the MIC of 10 mg mL-1. This however suggested that the oils obtained through acid-distillation showed the greatest activity than all other methods of extraction. Activity of the various extracts on bacteria showed that the ethanol extract had the highest activity on the tested organisms with MIC ranging between 0.625 and 1.25 mg mL-1. This was closely followed by the acid-extract (1.25 and 5.0 mg mL-1), methanol extract (1.25 and 10 mg mL-1), acetone extract (2.5 and 5.0 mg mL-1), and base extract (5.0 mg mL-1). Both cold water and hot water extracts showed the least activity of MIC, >10 mg mL-1. The antioxidant and free-radical scavenging activity of the obtained oils and extracts were tested by means of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH+) assay, [(2,2ˊ-azino bis-(3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS), nitric oxide and ferric reducing power assays. The oils and extracts showed DPPH radical scavenging ability, but not as high as the standard drugs. The base extract showed a higher reducing power than the standard drug, rutin. There were significant differences in the phytochemicals contents of the various leaf extracts. The acetone extract has the highest flavonol, proanthocyanidin, and alkaloid contents. The ethanol extract showed the highest amount of phenolic content with the acid extract, having the least. Thin layer chromatography (TLC) and column chromatography was employed to obtain different fractions of extracts using four eluent solvent systems of varying polarities: toluene, petroleum ether, hexane and ethyl acetate and sprayed with anisaldehyde. A single, visible spot of B-fraction was developed, collected and analyzed as 1-methyl-2,4,5- trinitroimidazole with renown valuable properties. , Thesis (PhD) -- Faculty of Science and Agriculture, 2015
- Full Text:
- Date Issued: 2015
The classification of fuzzy subgroups of some finite non-cyclic abelian p- groups of rank 3, with emphasis on the number of distinct fuzzy subgroups
- Authors: Appiah, Isaac Kwadwo
- Date: 2021-03
- Subjects: Fuzzy sets , Commutative algebra
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/20783 , vital:46563
- Description: In [6] and [7] we classi_ed fuzzy subgroups of some rank-3 abelian groups of the form G = Zpn + Zp + Zp for any _xed prime integer p and any positive integer n, using the natural equivalence relation de_ned in [40]. In this thesis, we extend our classi_cation of fuzzy subgroups in [6] to the group G = Zpn + Zpm + Zp for any _xed prime integer p; m = 2 and any positive integer n using the same natural equivalence relation studied in [40]. We present and prove explicit polynomial formulae for the number of (i) subgroups, (ii) maximal chains of subgroups of G for any n;m _ 2 and (iii) distinct fuzzy subgroups for m = 2 and n _ 2. We have also developed user-friendly polynomial formulae for the number of (iv) subgroups, (v) maximal chains for the group G = Zpn + Zpm for any n;m _ 2; any _xed prime positive integer p and (vi) distinct fuzzy subgroups of Zpn + Zpm for m equal to 2 and 3, and n _ 2 and provided their proofs. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-03
- Authors: Appiah, Isaac Kwadwo
- Date: 2021-03
- Subjects: Fuzzy sets , Commutative algebra
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/20783 , vital:46563
- Description: In [6] and [7] we classi_ed fuzzy subgroups of some rank-3 abelian groups of the form G = Zpn + Zp + Zp for any _xed prime integer p and any positive integer n, using the natural equivalence relation de_ned in [40]. In this thesis, we extend our classi_cation of fuzzy subgroups in [6] to the group G = Zpn + Zpm + Zp for any _xed prime integer p; m = 2 and any positive integer n using the same natural equivalence relation studied in [40]. We present and prove explicit polynomial formulae for the number of (i) subgroups, (ii) maximal chains of subgroups of G for any n;m _ 2 and (iii) distinct fuzzy subgroups for m = 2 and n _ 2. We have also developed user-friendly polynomial formulae for the number of (iv) subgroups, (v) maximal chains for the group G = Zpn + Zpm for any n;m _ 2; any _xed prime positive integer p and (vi) distinct fuzzy subgroups of Zpn + Zpm for m equal to 2 and 3, and n _ 2 and provided their proofs. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-03
Insights into the drivers and impact of climate change and climate change adaptation in the Eastern Cape, South Africa: the case of Amathole District Municipality
- Authors: Gwala, Lindokuhle
- Date: 2022-11
- Subjects: Climatic changes , Climatic factors , Global environmental change
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27832 , vital:69945
- Description: Climate change is a threat to communal livestock production, causing increases in the rate and intensity of droughts, floods, pests and diseases, and thus subjecting communal livestock production to vulnerability. Communal farmers rely on rain-fed agriculture and are usually too poorly resourced to cope with the frequency of climate-related events that may be expected in the future. Response and adaptation is vital to ensure the sustainability of livestock production, particularly since it is the main source of survival in communal areas. The Eastern Cape Provincial Policy on Climate Change was introduced in 2010 to facilitate a coordinated approach that assists farmers to respond, adapt and mitigate climate change. The study examines the implementation of the policy to identify farmers’ perceptions of the response rate prior to, during and after climate change disasters. In addition, the study establishes the characteristics of livestock production in the study area, seeking to ascertain how communal livestock farmers CLFs are adapting their practices to ensure sustainable livestock production in the face of climate change. In order to make informed decisions on coping strategies, farmers require access to information on climate change. The study therefore examines the communication channels used by farmers to access such information. Since food security is under threat, the study also assesses the effects of climate change on food security among the CLFs. Multi stage sampling was used to select 388 communal livestock farmers in three local municipalities in Amathole District Municipality. A cross-sectional survey was carried out in five communities randomly selected in the three local municipalities, with data collected by means of a semi-structured questionnaire. Descriptive statistics, inferential statistics, principal component analysis and regression methods were used to analyse the data. The study reveals that communal livestock farmers perceive a poor response rate from extension services before, during and after disasters, and that they have poor access to support materials. All of the respondents practised uncontrolled breeding, attributed to a lack of infrastructure such as fencing. Most farmers kept cattle for income generation. The major constraints of cattle production were diseases and pests. CLFs employed dipping, rotational grazing, water tanks, veld burning and the sale of animals as the main strategies to cope with climate change. CLFs access climate change information through multiple channels. The main sources were other farmers and media such as radio and television, although language barriers hampered full understanding of information conveyed about climate chnage. Farmer-to-farmer contact was a central aspect of the CLFs’ lives that could be better employed in the dissemination of climate change information. The results suggest a positive relationship between diversity of species kept and food security. Assets, the social safety net (mainly grants) and adaptive capacity indicators positively and significantly impacted households’ resilience to food insecurity. The study recommends that the capacity of communal livestock farmers on effective mitigating strategies be improved, making use of mass media; that more work be done by extension services to prepare farmers for adverse events and that relief materials disseminated during periods of disaster be tagged “national emergency” to speed up distribution and use. There is an urgent need for adequate and timely provision of climate change information that will help CLFs to make more effective use of their resources in the face of climate change. Agricultural extension services should address challenges associated with breeding practices, disaster response and adult illiteracy to promote better adaptive capacity and ensure food security among this vulnerable cohort. , Thesis (MSci) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-11
- Authors: Gwala, Lindokuhle
- Date: 2022-11
- Subjects: Climatic changes , Climatic factors , Global environmental change
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27832 , vital:69945
- Description: Climate change is a threat to communal livestock production, causing increases in the rate and intensity of droughts, floods, pests and diseases, and thus subjecting communal livestock production to vulnerability. Communal farmers rely on rain-fed agriculture and are usually too poorly resourced to cope with the frequency of climate-related events that may be expected in the future. Response and adaptation is vital to ensure the sustainability of livestock production, particularly since it is the main source of survival in communal areas. The Eastern Cape Provincial Policy on Climate Change was introduced in 2010 to facilitate a coordinated approach that assists farmers to respond, adapt and mitigate climate change. The study examines the implementation of the policy to identify farmers’ perceptions of the response rate prior to, during and after climate change disasters. In addition, the study establishes the characteristics of livestock production in the study area, seeking to ascertain how communal livestock farmers CLFs are adapting their practices to ensure sustainable livestock production in the face of climate change. In order to make informed decisions on coping strategies, farmers require access to information on climate change. The study therefore examines the communication channels used by farmers to access such information. Since food security is under threat, the study also assesses the effects of climate change on food security among the CLFs. Multi stage sampling was used to select 388 communal livestock farmers in three local municipalities in Amathole District Municipality. A cross-sectional survey was carried out in five communities randomly selected in the three local municipalities, with data collected by means of a semi-structured questionnaire. Descriptive statistics, inferential statistics, principal component analysis and regression methods were used to analyse the data. The study reveals that communal livestock farmers perceive a poor response rate from extension services before, during and after disasters, and that they have poor access to support materials. All of the respondents practised uncontrolled breeding, attributed to a lack of infrastructure such as fencing. Most farmers kept cattle for income generation. The major constraints of cattle production were diseases and pests. CLFs employed dipping, rotational grazing, water tanks, veld burning and the sale of animals as the main strategies to cope with climate change. CLFs access climate change information through multiple channels. The main sources were other farmers and media such as radio and television, although language barriers hampered full understanding of information conveyed about climate chnage. Farmer-to-farmer contact was a central aspect of the CLFs’ lives that could be better employed in the dissemination of climate change information. The results suggest a positive relationship between diversity of species kept and food security. Assets, the social safety net (mainly grants) and adaptive capacity indicators positively and significantly impacted households’ resilience to food insecurity. The study recommends that the capacity of communal livestock farmers on effective mitigating strategies be improved, making use of mass media; that more work be done by extension services to prepare farmers for adverse events and that relief materials disseminated during periods of disaster be tagged “national emergency” to speed up distribution and use. There is an urgent need for adequate and timely provision of climate change information that will help CLFs to make more effective use of their resources in the face of climate change. Agricultural extension services should address challenges associated with breeding practices, disaster response and adult illiteracy to promote better adaptive capacity and ensure food security among this vulnerable cohort. , Thesis (MSci) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-11
Water restriction and vitamin c supplementation on Xhosa goats during summer: Effect on growth performance, blood biochemical profile, nutrient balance, carcass characteristics and meat quality
- Akinmoladun, Oluwakamisi Festus https://orcid.org/0000-0001-6462-374X
- Authors: Akinmoladun, Oluwakamisi Festus https://orcid.org/0000-0001-6462-374X
- Date: 2020-08
- Subjects: Goats -- Nutrition , Goats -- Feeding and feeds
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22710 , vital:52664
- Description: This study aimed to evaluate the effect of single and extra vitamin C (VC) supplementation on water-stressed Xhosa goats during the summer by evaluating their growth performance, blood biochemical profile, nutrient balance, carcass characteristics and meat qualities. The objectives were to assess the effect of water restriction and vitamin C supplementation by evaluating: firstly, growth performance, heat tolerance responses, and blood metabolites; secondly, intake, nutrient digestibility, nitrogen and mineral balance; thirdly, stress indices, carcass characteristics and meat qualities parameters and lastly, fatty acid profile, oxidative stability of lipids and sensory attributes were evaluated. To achieve these objectives, forty-two (42) goats were divided equally into seven treatments (75-day trial); without water restriction (W0, control); water restriction of 70percent of ad libitum water intake WI (W70); water restriction of 50percent ad libitum WI (W50); water restriction of 70percent of ad libitum WI plus 3g VC daily (W70+); water restriction 50percent of ad libitum WI plus 3g VC daily (W50+); water restriction of 70percent of ad libitumWI plus 3g VC and extra 5gVC given every eight-day (70++); water restriction of 50percent of ad libitum WI plus 3g VC and extra 5gVC given every eight-day (W50++). In the first objective, growth performance parameters, body condition scores, rectal temperature, respiratory rate, heat tolerance response parameters and blood metabolites were measured.Weight loss due to water restriction was reduced by VC supplementation in treated groups. The attenuation effect of VC was significant (P<0.05) in responses to respiratory rate (RR), Na+, K+, Mg2+, Cl-, Ca2+ and urea. Supplementation of VC (either single or multiple) did not (P>0.05) improve the effect of water restriction on body condition scores (BCs), FAMACHA©, glucose, globulin, alanine aminotransferase (ALT) and high-density lipoprotein (HDL). In the second objective, intake, nutrient digestibility, nitrogen and mineral balance were evaluated. The reduced nutrient intake was similar (P>0.05) irrespective of water restrictions and VC supplementations. Water-restriction levels did not affect nutrient intake/metabolic weight. Retained nitrogen increased with water-restriction levels but not influenced by VC. NH3-N decreased with the levels of water restriction while the pH was similar across the water restricted groups. Supplementation of VC had no effect (P>0.05) on apparent digestibility and digestible nutrients induced by water restriction levels. The amount of Ca, K, Mg retained increased (P<0.05) with water-restriction levels. In the third objective, stress indices, carcass characteristics and meat quality parameters were evaluated. The level of plasma cortisol concentration due to water stress was lessened (P<0.05) by VC. Follicle stimulating hormone (FSH), Luteinizing hormone (LH) and insulin were not affected (P>0.05) by levels of water restriction. The hot and carcass weights were lower (P<0.05) in W70+ and W50+ compared to W70 and W50 respectively. Vitamin C treated goats had higher redness (a*) compared to W70, W50 and W0. The shear force and cooking loss increased (P<0.05) with water restriction levels, while thaw loss, pH45min and pH24h were not affected by water restriction levels. In the final objective, the treatments did not affect (P>0.05) the oxidative stability of lipids (TBARS). The moisture and fat content in the water restricted groups were lower (P<0.05) than W0. The consumer meat sensory appearance decreased (P<0.05) with levels of water restrictions. Regardless of VC concentration and supplementation, vaccenic, and docosahexaenoic acid increased (P<0.05) while linolenic acid decreased as the water restriction levels increased. Nonetheless, treatment did not affect (P>0.05) the saturated and unsaturated fatty acids. These studies showed that suboptimal water intake negatively affects the growth performance and nutrient intake of Xhosa goats. However, the reduction in body weight loss and decreased plasma cortisol (chief stress hormone) concentration following vitamin C supplementation (especially at a daily single dose [3g/d]) may well reduce the effect of water stress in goats. , Thesis (PhD) -- Faculty of Science and Agriculture, 2020
- Full Text:
- Date Issued: 2020-08
- Authors: Akinmoladun, Oluwakamisi Festus https://orcid.org/0000-0001-6462-374X
- Date: 2020-08
- Subjects: Goats -- Nutrition , Goats -- Feeding and feeds
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22710 , vital:52664
- Description: This study aimed to evaluate the effect of single and extra vitamin C (VC) supplementation on water-stressed Xhosa goats during the summer by evaluating their growth performance, blood biochemical profile, nutrient balance, carcass characteristics and meat qualities. The objectives were to assess the effect of water restriction and vitamin C supplementation by evaluating: firstly, growth performance, heat tolerance responses, and blood metabolites; secondly, intake, nutrient digestibility, nitrogen and mineral balance; thirdly, stress indices, carcass characteristics and meat qualities parameters and lastly, fatty acid profile, oxidative stability of lipids and sensory attributes were evaluated. To achieve these objectives, forty-two (42) goats were divided equally into seven treatments (75-day trial); without water restriction (W0, control); water restriction of 70percent of ad libitum water intake WI (W70); water restriction of 50percent ad libitum WI (W50); water restriction of 70percent of ad libitum WI plus 3g VC daily (W70+); water restriction 50percent of ad libitum WI plus 3g VC daily (W50+); water restriction of 70percent of ad libitumWI plus 3g VC and extra 5gVC given every eight-day (70++); water restriction of 50percent of ad libitum WI plus 3g VC and extra 5gVC given every eight-day (W50++). In the first objective, growth performance parameters, body condition scores, rectal temperature, respiratory rate, heat tolerance response parameters and blood metabolites were measured.Weight loss due to water restriction was reduced by VC supplementation in treated groups. The attenuation effect of VC was significant (P<0.05) in responses to respiratory rate (RR), Na+, K+, Mg2+, Cl-, Ca2+ and urea. Supplementation of VC (either single or multiple) did not (P>0.05) improve the effect of water restriction on body condition scores (BCs), FAMACHA©, glucose, globulin, alanine aminotransferase (ALT) and high-density lipoprotein (HDL). In the second objective, intake, nutrient digestibility, nitrogen and mineral balance were evaluated. The reduced nutrient intake was similar (P>0.05) irrespective of water restrictions and VC supplementations. Water-restriction levels did not affect nutrient intake/metabolic weight. Retained nitrogen increased with water-restriction levels but not influenced by VC. NH3-N decreased with the levels of water restriction while the pH was similar across the water restricted groups. Supplementation of VC had no effect (P>0.05) on apparent digestibility and digestible nutrients induced by water restriction levels. The amount of Ca, K, Mg retained increased (P<0.05) with water-restriction levels. In the third objective, stress indices, carcass characteristics and meat quality parameters were evaluated. The level of plasma cortisol concentration due to water stress was lessened (P<0.05) by VC. Follicle stimulating hormone (FSH), Luteinizing hormone (LH) and insulin were not affected (P>0.05) by levels of water restriction. The hot and carcass weights were lower (P<0.05) in W70+ and W50+ compared to W70 and W50 respectively. Vitamin C treated goats had higher redness (a*) compared to W70, W50 and W0. The shear force and cooking loss increased (P<0.05) with water restriction levels, while thaw loss, pH45min and pH24h were not affected by water restriction levels. In the final objective, the treatments did not affect (P>0.05) the oxidative stability of lipids (TBARS). The moisture and fat content in the water restricted groups were lower (P<0.05) than W0. The consumer meat sensory appearance decreased (P<0.05) with levels of water restrictions. Regardless of VC concentration and supplementation, vaccenic, and docosahexaenoic acid increased (P<0.05) while linolenic acid decreased as the water restriction levels increased. Nonetheless, treatment did not affect (P>0.05) the saturated and unsaturated fatty acids. These studies showed that suboptimal water intake negatively affects the growth performance and nutrient intake of Xhosa goats. However, the reduction in body weight loss and decreased plasma cortisol (chief stress hormone) concentration following vitamin C supplementation (especially at a daily single dose [3g/d]) may well reduce the effect of water stress in goats. , Thesis (PhD) -- Faculty of Science and Agriculture, 2020
- Full Text:
- Date Issued: 2020-08
Production and biochemical characterization of new bioflocculants from bacteria isolated from freshwater and marine environments of the Eastern Cape in South Africa
- Mabinya, Leonard Vuyani https://orcid.org/0000-0002-0682-7282
- Authors: Mabinya, Leonard Vuyani https://orcid.org/0000-0002-0682-7282
- Date: 2013-01
- Subjects: Flocculation , Bacteria
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24228 , vital:62445
- Description: The production and characterization of bioflocculants produced by three bacteria belonging to Arthrobacter, Halomonas and Micrococcus genera and isolated from freshwater and marine environments were evaluated both as axenic cultures and as consortia. The influences of cultutre conditions such as carbon, nitrogen and metal ions sources, as well as initial pH on bioflocculant production by individual isolates were investigated. Both Arthrobacter sp. Raats and Halomonas sp. Okoh utilized urea as a nitrogen source of choice for optimal production of the bioflocculants with Micrococcus sp. Leo having a preference for peptone. All three strains differed in as far as the carbon source of choice was concerned with lactose, glucose and sucrose the preferred carbon sources respectively. Also, all three bacterial strains produced an extracellular bioflocculant aerobically but an intial pH 7.0 of the culture media was suitable for both Arthrobacter sp. Raats and Halomonas sp. Okoh with a slightly alkaline pH of 9.0 preferred by Micrococcus sp. Leo. The presence of Mg2+ cations stimulated bioflocculant production by both Arthrobacter sp. Raats and Micrococcus sp. Leo while Ca2+ resulted in more efficient bioflocculant production by Halomonas sp. Okoh. Chemical analyses revealed the bioflocculants produced by both Halomonas sp. Okoh and Micrococcus sp. Leo to be predominantly polysaccharides whereas Arthrobacter sp. Raats produced principally a glycoprotein composed of about 56percent protein and 25percent total carbohydrate. Response surface methodology (RSM) was used to optimize production medium for bioflocculant production by a consortium of Halomonas sp. Okoh and Micrococcus sp. Leo. Plackett-Burman experimental design showed that fructose, ammonium sulphate and MgCl2 were significant in the high yield of the bioflocculant. Furthermore, central composite design showed that optimal concentration of these critical nutritional sources were 16.14 g/L, 1.55 g/L and 1.88 g/L for fructose, ammonium sulphate and MgCl2 respectively. Quantification of the bioflocculant showed a yield of 6.43 g/L which was in close accord with the predicted value of 6.51 g/L. FTIR spectrometry of the bioflocculant indicated the presence of carboxyl, hydroxyl and amino groups, typical for heteropolysaccharide, while SEM imaging revealed a lattice-like structure. The efficiency of the nutrient optimization suggests suitability for industrial applicability. , Thesis (PhD) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013-01
- Authors: Mabinya, Leonard Vuyani https://orcid.org/0000-0002-0682-7282
- Date: 2013-01
- Subjects: Flocculation , Bacteria
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24228 , vital:62445
- Description: The production and characterization of bioflocculants produced by three bacteria belonging to Arthrobacter, Halomonas and Micrococcus genera and isolated from freshwater and marine environments were evaluated both as axenic cultures and as consortia. The influences of cultutre conditions such as carbon, nitrogen and metal ions sources, as well as initial pH on bioflocculant production by individual isolates were investigated. Both Arthrobacter sp. Raats and Halomonas sp. Okoh utilized urea as a nitrogen source of choice for optimal production of the bioflocculants with Micrococcus sp. Leo having a preference for peptone. All three strains differed in as far as the carbon source of choice was concerned with lactose, glucose and sucrose the preferred carbon sources respectively. Also, all three bacterial strains produced an extracellular bioflocculant aerobically but an intial pH 7.0 of the culture media was suitable for both Arthrobacter sp. Raats and Halomonas sp. Okoh with a slightly alkaline pH of 9.0 preferred by Micrococcus sp. Leo. The presence of Mg2+ cations stimulated bioflocculant production by both Arthrobacter sp. Raats and Micrococcus sp. Leo while Ca2+ resulted in more efficient bioflocculant production by Halomonas sp. Okoh. Chemical analyses revealed the bioflocculants produced by both Halomonas sp. Okoh and Micrococcus sp. Leo to be predominantly polysaccharides whereas Arthrobacter sp. Raats produced principally a glycoprotein composed of about 56percent protein and 25percent total carbohydrate. Response surface methodology (RSM) was used to optimize production medium for bioflocculant production by a consortium of Halomonas sp. Okoh and Micrococcus sp. Leo. Plackett-Burman experimental design showed that fructose, ammonium sulphate and MgCl2 were significant in the high yield of the bioflocculant. Furthermore, central composite design showed that optimal concentration of these critical nutritional sources were 16.14 g/L, 1.55 g/L and 1.88 g/L for fructose, ammonium sulphate and MgCl2 respectively. Quantification of the bioflocculant showed a yield of 6.43 g/L which was in close accord with the predicted value of 6.51 g/L. FTIR spectrometry of the bioflocculant indicated the presence of carboxyl, hydroxyl and amino groups, typical for heteropolysaccharide, while SEM imaging revealed a lattice-like structure. The efficiency of the nutrient optimization suggests suitability for industrial applicability. , Thesis (PhD) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013-01
Genetic diversity, resistance profile of HIV and risk assessment of mother-to-child transmission in pregnant women on anti-retroviral therapy in the Eastern Cape, South Africa
- Authors: Adeniyi, Oladele Vincent
- Date: 2018-12
- Subjects: Antiretroviral agents http://id.loc.gov/authorities/subjects/sh2003006231 , AIDS (Disease) in infants http://id.loc.gov/authorities/subjects/sh90004332
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/19817 , vital:43254
- Description: Despite the initiation of life-long ART in HIV-infected pregnant women, the rate and determinants of infant HIV transmission are not known, especially in the poor resource settings of the Eastern Cape, South Africa. Maternal anti-retroviral therapy (ART) is crucial for elimination of mother-to-child transmission (MTCT) of HIV. However, the inevitable risks of emergence of HIV drug resistance poses significant threat to achieving this goal of HIV-free generation and keeping mothers alive. Also, it is unclear if women with high viral load at delivery have acquired clinically relevant mutations, which could confer resistance to the ART, thus, further increasing the risks of motherto- child transmission of HIV-drug resistance strains. In addition to the gaps identified in the prevention of mother-to-child transmission (PMTCT) context, the understanding of regional epidemics is crucial to the broader epidemiological profiling of HIV infections in the country. Despite the rapid influx of foreign nationals to South African and Eastern Cape Province, there has not been any molecular epidemiological studies profiling the HIV diversity in the Eastern Cape. , Thesis (PhD) (Microbiology) -- University of Fort Hare, 2018
- Full Text:
- Date Issued: 2018-12
- Authors: Adeniyi, Oladele Vincent
- Date: 2018-12
- Subjects: Antiretroviral agents http://id.loc.gov/authorities/subjects/sh2003006231 , AIDS (Disease) in infants http://id.loc.gov/authorities/subjects/sh90004332
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/19817 , vital:43254
- Description: Despite the initiation of life-long ART in HIV-infected pregnant women, the rate and determinants of infant HIV transmission are not known, especially in the poor resource settings of the Eastern Cape, South Africa. Maternal anti-retroviral therapy (ART) is crucial for elimination of mother-to-child transmission (MTCT) of HIV. However, the inevitable risks of emergence of HIV drug resistance poses significant threat to achieving this goal of HIV-free generation and keeping mothers alive. Also, it is unclear if women with high viral load at delivery have acquired clinically relevant mutations, which could confer resistance to the ART, thus, further increasing the risks of motherto- child transmission of HIV-drug resistance strains. In addition to the gaps identified in the prevention of mother-to-child transmission (PMTCT) context, the understanding of regional epidemics is crucial to the broader epidemiological profiling of HIV infections in the country. Despite the rapid influx of foreign nationals to South African and Eastern Cape Province, there has not been any molecular epidemiological studies profiling the HIV diversity in the Eastern Cape. , Thesis (PhD) (Microbiology) -- University of Fort Hare, 2018
- Full Text:
- Date Issued: 2018-12
Compartmentalization of mineral elements, nutritional factors, biological potentials and phytochemical profiles in the fruits of Musa sinensis L.(Banana) and Musa paradisiaca L.(Plantain): A comparison among soft flesh, peel and boiled peel extract
- Oyeyinka, Barnabas Oluwatomide https://orcid.org/0000-0003-1191-9365
- Authors: Oyeyinka, Barnabas Oluwatomide https://orcid.org/0000-0003-1191-9365
- Date: 2021-09
- Subjects: Bananas , Plantain banana
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23655 , vital:58274
- Description: Fruits are key contributors to human nutrition and health. However, banana and plantain are typical examples of fruits that have nutritionally under-utilized peel by-products. This study was thus carried out to investigate the compartmental distribution (soft flesh, peel, and boiled peel extract) of mineral elements, nutritional factors, biological potentials, and phytochemical profiles in M. sinensis and M. paradisiaca fruits (ripening stage 4-5), with focus on the peels. Proximal and and antinutritive analyses were done with standard methods of the Association of Official Analytical Chemists (AOAC), while mineral element composition in the fruit components was analyzed with the inductively coupled plasma optical emission spectroscopy (ICP-OES). The pharmacological potential of M. sinensis and M. paradisiaca fruit components was investigated spectrophotometrically by evaluating the polyphenolic constituents (total phenol, proanthocyanidin, flavonoid) and in vitro radical scavenging activities of the aqueous, acetone and ethanol extracts, using DPPH, ABTS, and FRAP assay models. The correlational evaluation of the polyphenolics and antioxidant activity in the components of both fruits using Pearson’s correlational coefficient (r). The proximal assays revealed that moisture content, fiber content, and carbohydratecontent were substantially present in the flesh and peel of M. sinensis and M. paradisiaca, while lipid content was low. The antinutritive results revealed safe levels of alkaloid, oxalate, phytate, and saponin factors in the flesh and peel by-products. Mineral analysis results indicated substantial levels of the macroelements K, Mg, Ca, and P in the peels. Other results revealed that acetone extracts had the highest phenolic, proanthocyanidin and flavonoid constituents respectively, across the soft flesh components ofM. sinensis (119.05 ± 5.80 mgGAE/g; 337.48 ± 13.16 mgCE/g; 602.64 ± 3.65 mgQE/g), M. paradisiaca (114.80 ± 1.49 mgGAE/g; 436.09 ± 36.44 mgCE/g; 777.35 ± 150.95mgQE/g) and the peel component of M. paradisiaca (136.87 ± 5.69 mgGAE/g; 530.06 ± 53.51 mgCE/g; 750.87 ± 55.61 mgQE/g), with an exception of the phenolic content of M. sinensis peel, where it was highest in the ethanol extract (157.19 ± 4.76 mgGAE/g). The ABTS (0.03 mg/mL) and DPPH (0.03 mg/mL) activities were at their highest in the boiled peel extracts of M. sinensis and M. paradisiaca, while ferric reducing power was highest in ethanol extracts across M. sinensis soft flesh, peel, and M. paradisiaca flesh. Acetone extract of M. paradisiaca peel had the highest ferric reducing capacity at peak concentration (0.1 mg/mL). Correlational analysis revealed a negative correlation between respective phenolic, proanthocyanidin, and flavonoid content and the IC50DPPH antioxidant capacity in M. sinensis flesh, M. sinensis peel and M. paradisiaca flesh. Conversely, there was positive correlation between IC50 DPPH with proanthocyanidin and flavonoid in M. paradisiaca peel. Negative correlation was detected between the phenolic, proanthocyanidin and flavonoid contents and IC50ABTS in M. sinensis flesh. Positive correlation was observed between respective phenolic, proanthocyanidin and flavonoid contentwith IC50 ABTS in M. sinensis peel, M. paradisiaca flesh and M. paradisiaca peel. There was negative correlation between the respective phenolic, proanthocyanidin and flavonoid contents and IC50 FRAP in the flesh of M. sinensis, while positive correlation was observed in M. sinensis peel. M. paradisiaca flesh on the other hand, showed positive correlation between the IC50 FRAP and the respective phytochemical contents. However, the peel, there was negative correlation. The correlational evaluation in this study revealed general positive and negative correlational patterns, which implies that no polyphenolic constituent contributed exclusively to antioxidant activity, but rather in combination. Ultrastructure and elemental spectra of M. sinensis and M. paradisiaca exocarps were analysed with electron microscopy (SEM)and energy dispersive x-ray (EDX). Microstructures such as interlocked, polyhedral epidermal cells, ellipsoid-shaped stomata, guard cells, intercellular space, anticlinal-patterned walls, and subsidiary cells were observed. The elemental spectra revealed the presence of elements such as potassium, iron, carbon, oxygen, silicon, and gold, with consistently high to relatively high carbon and oxygen peaks in M. sinensis and M. paradisiaca exocarps. The relative similarity observed in the constituents of a number of the elemental spectra in M. sinensis and M. paradisiaca peels, reflects some degree of relatedness. These outcomes indicate that banana and plantain peel and boiled peel extracts are nutritive, medicinal and potential nutraceuticals, with food preservative, shelf-life and quality enhancement potentials. The instrumentation in this study also have potential relevance in industrial food product analysis. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Oyeyinka, Barnabas Oluwatomide https://orcid.org/0000-0003-1191-9365
- Date: 2021-09
- Subjects: Bananas , Plantain banana
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23655 , vital:58274
- Description: Fruits are key contributors to human nutrition and health. However, banana and plantain are typical examples of fruits that have nutritionally under-utilized peel by-products. This study was thus carried out to investigate the compartmental distribution (soft flesh, peel, and boiled peel extract) of mineral elements, nutritional factors, biological potentials, and phytochemical profiles in M. sinensis and M. paradisiaca fruits (ripening stage 4-5), with focus on the peels. Proximal and and antinutritive analyses were done with standard methods of the Association of Official Analytical Chemists (AOAC), while mineral element composition in the fruit components was analyzed with the inductively coupled plasma optical emission spectroscopy (ICP-OES). The pharmacological potential of M. sinensis and M. paradisiaca fruit components was investigated spectrophotometrically by evaluating the polyphenolic constituents (total phenol, proanthocyanidin, flavonoid) and in vitro radical scavenging activities of the aqueous, acetone and ethanol extracts, using DPPH, ABTS, and FRAP assay models. The correlational evaluation of the polyphenolics and antioxidant activity in the components of both fruits using Pearson’s correlational coefficient (r). The proximal assays revealed that moisture content, fiber content, and carbohydratecontent were substantially present in the flesh and peel of M. sinensis and M. paradisiaca, while lipid content was low. The antinutritive results revealed safe levels of alkaloid, oxalate, phytate, and saponin factors in the flesh and peel by-products. Mineral analysis results indicated substantial levels of the macroelements K, Mg, Ca, and P in the peels. Other results revealed that acetone extracts had the highest phenolic, proanthocyanidin and flavonoid constituents respectively, across the soft flesh components ofM. sinensis (119.05 ± 5.80 mgGAE/g; 337.48 ± 13.16 mgCE/g; 602.64 ± 3.65 mgQE/g), M. paradisiaca (114.80 ± 1.49 mgGAE/g; 436.09 ± 36.44 mgCE/g; 777.35 ± 150.95mgQE/g) and the peel component of M. paradisiaca (136.87 ± 5.69 mgGAE/g; 530.06 ± 53.51 mgCE/g; 750.87 ± 55.61 mgQE/g), with an exception of the phenolic content of M. sinensis peel, where it was highest in the ethanol extract (157.19 ± 4.76 mgGAE/g). The ABTS (0.03 mg/mL) and DPPH (0.03 mg/mL) activities were at their highest in the boiled peel extracts of M. sinensis and M. paradisiaca, while ferric reducing power was highest in ethanol extracts across M. sinensis soft flesh, peel, and M. paradisiaca flesh. Acetone extract of M. paradisiaca peel had the highest ferric reducing capacity at peak concentration (0.1 mg/mL). Correlational analysis revealed a negative correlation between respective phenolic, proanthocyanidin, and flavonoid content and the IC50DPPH antioxidant capacity in M. sinensis flesh, M. sinensis peel and M. paradisiaca flesh. Conversely, there was positive correlation between IC50 DPPH with proanthocyanidin and flavonoid in M. paradisiaca peel. Negative correlation was detected between the phenolic, proanthocyanidin and flavonoid contents and IC50ABTS in M. sinensis flesh. Positive correlation was observed between respective phenolic, proanthocyanidin and flavonoid contentwith IC50 ABTS in M. sinensis peel, M. paradisiaca flesh and M. paradisiaca peel. There was negative correlation between the respective phenolic, proanthocyanidin and flavonoid contents and IC50 FRAP in the flesh of M. sinensis, while positive correlation was observed in M. sinensis peel. M. paradisiaca flesh on the other hand, showed positive correlation between the IC50 FRAP and the respective phytochemical contents. However, the peel, there was negative correlation. The correlational evaluation in this study revealed general positive and negative correlational patterns, which implies that no polyphenolic constituent contributed exclusively to antioxidant activity, but rather in combination. Ultrastructure and elemental spectra of M. sinensis and M. paradisiaca exocarps were analysed with electron microscopy (SEM)and energy dispersive x-ray (EDX). Microstructures such as interlocked, polyhedral epidermal cells, ellipsoid-shaped stomata, guard cells, intercellular space, anticlinal-patterned walls, and subsidiary cells were observed. The elemental spectra revealed the presence of elements such as potassium, iron, carbon, oxygen, silicon, and gold, with consistently high to relatively high carbon and oxygen peaks in M. sinensis and M. paradisiaca exocarps. The relative similarity observed in the constituents of a number of the elemental spectra in M. sinensis and M. paradisiaca peels, reflects some degree of relatedness. These outcomes indicate that banana and plantain peel and boiled peel extracts are nutritive, medicinal and potential nutraceuticals, with food preservative, shelf-life and quality enhancement potentials. The instrumentation in this study also have potential relevance in industrial food product analysis. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
A study of the selected wild edible plants utilized by indigenous people of the Amathole District in the Eastern Cape Province of South Africa
- Kwinana-Mandindi, Thozama Ndileka
- Authors: Kwinana-Mandindi, Thozama Ndileka
- Date: 2012
- Subjects: Wild plants, Edible http://id.loc.gov/authorities/subjects/sh85146686
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/19598 , vital:43147
- Description: Wild edible plants are an indispensible part of diets in some of the poor resourced rural societies. In many less resourced households a main meal comprises of a starch staple which is accompanied by a supplement of vegetables that provide the other nutritional elements as well as flavour to the meals. The vegetable relish (isishebo) thus, becomes an important component of the diet. The sustenance of many such resource poor indigenous societies over many generations has been as a result of their reliance on a readily available supply of their nutritional requirements, where edible wild plants formed the major food source. Wild edible plants provided the most important source of nutritional supply even during times of drought and famine. However, lifestyle changes have caused a serious reduction of the gathering and use of the wild edible vegetables, knowledge about them and the local culture are also lost with them. Unfortunately, others have come to regard their traditional food resource base as primitive and inferior and have come to rely on new exotic food plant whose supply is unstable and narrow compared to the wide variety of wild edible plants. Even when drought challenges play destruction with food availability, resulting in food shortages due to the reliance on cultivated crops that are poorly adapted to local conditions, communities cannot go back to the unknown food plants. However, detailed scientific investigations are needed to understand and preserve wild food uses. This study was undertaken to add to that body of knowledge. It started with an ethnobotanic survey of the use of wild food plants in 10 selected rural villages and peri-urban dwellings in the Amathole District of the Eastern Cape. These rural areas were chosen because of the belief that there are still individuals who possess the wealth of traditional knowledge within those remote areas in addition to that the villages are surrounded by indigenous vegetation from which they could be harvesting some indigenous food plants. Furthermore, the relationship between people and plants are often clearer in indigenous/traditional societies since the link between production and consumption is more direct. Besides the survey, this research employed various methods including Inductively Coupled Argon (ICP) analyses of minerals and vitamins, determination of phytochemicals and antioxidant/bio-activity that of, higher performance liquid chromatography (HPLC) determination of other vitamins, assessment of proximate and anti-nutrient compositions of raw and cooked samples of plants, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDXS) to look into the micro-morphology of leaves for details that might have a bearing in the nutrient composition of the wild edible vegetables. This was done with the aim to explore and highlight the wild-food-plant base of indigenous people, to investigate the nutritional value of the selected frequently consumed wild vegetables and to recommend ways of educating people on the value of such plants and the need to promote their continued sustainable use as well as preservation of them for the benefit of people who cannot afford a continuous nutritious meal particularly among rural communities. Twenty-five (25) indigenous wild food plants which included leafy vegetables, nuts and fruits species were identified as being arbitrarily gathered and utilised as food, of which seven wild leafy vegetable species were often mentioned as common among the 15 dwellings surveyed and most frequently consumed by the respondents. Two additional plants were also frequently used as flavoring and in their raw state respectively. Wild edible vegetables were mainly eaten boiled as ‘laxa’, mixed with maize meal as ‘imifino’, fried as relish ‘isishebo’ or raw for both snacking purposes and medicinal functions. Wild edible plant species in the Amathole District of the Eastern Cape-South Africa were documented with respect to their uses and knowledge or identification. Four indigenous wild vegetables (Chenopodium album, Solanum nigrum/nodiflorum, Amaranthus dubius and Urtica lobulata) frequently consumed by the indigenous communities in the study region were selected. All the plant species had a remarkably high content of pro-anthocyanidins (between 58.42 and 65.18 mg/g) and also exhibited high radical scavenging activity in vitro. S. nigrum and C. album were found to be rich sources of ascorbic acid, having 1.05mg/100g and 1.01mg/100g, respectively. The entire wild, traditionally edible plants contain reasonably good concentrations of riboflavin while U. lobulata was found to contain maximum amount of thiamine. All plant species were rich sources of minerals and vitamins (both water soluble and fat soluble). Appropriate cooking methods are to be used to enhance the bio-availability of vitamins and nutrients in general. Cooking generally improved the nutritive value in certain wild vegetables. However, some nutrients were drained away. For example micro-nutrient and anti-nutrient component in the ash were reduced in cooking. The EDXS analysis has shown that the indigenous, wild vegetables in the Amathole District of South Africa are excellent sources of minerals, while the mineral crystals present at the level of the mesophyll of the indigenous wild vegetables were probably mixtures of calcium oxalate, calcium sulphate and silica. Saponin, tannins, oxalates, phytates and alkaloids are present in all the indigenous wild vegetables, but in minimal safe quantities. Nutritional analysis of some wild food plants demonstrates that in many cases the nutritional quality of the plants is comparable and in some cases even superior to domesticated exotic varieties. Knowledge about gathering and use of some wild food species is common among the rural dwellers. However, most uses are known by few elderly informants only. Education, awareness campaigns and revival of use of wild edible plants directed at the youth particularly is essential and this can be done through all forms of media. , Thesis (PhD) (Ethnobotany) -- University of Fort Hare, 2012
- Full Text:
- Date Issued: 2012
- Authors: Kwinana-Mandindi, Thozama Ndileka
- Date: 2012
- Subjects: Wild plants, Edible http://id.loc.gov/authorities/subjects/sh85146686
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/19598 , vital:43147
- Description: Wild edible plants are an indispensible part of diets in some of the poor resourced rural societies. In many less resourced households a main meal comprises of a starch staple which is accompanied by a supplement of vegetables that provide the other nutritional elements as well as flavour to the meals. The vegetable relish (isishebo) thus, becomes an important component of the diet. The sustenance of many such resource poor indigenous societies over many generations has been as a result of their reliance on a readily available supply of their nutritional requirements, where edible wild plants formed the major food source. Wild edible plants provided the most important source of nutritional supply even during times of drought and famine. However, lifestyle changes have caused a serious reduction of the gathering and use of the wild edible vegetables, knowledge about them and the local culture are also lost with them. Unfortunately, others have come to regard their traditional food resource base as primitive and inferior and have come to rely on new exotic food plant whose supply is unstable and narrow compared to the wide variety of wild edible plants. Even when drought challenges play destruction with food availability, resulting in food shortages due to the reliance on cultivated crops that are poorly adapted to local conditions, communities cannot go back to the unknown food plants. However, detailed scientific investigations are needed to understand and preserve wild food uses. This study was undertaken to add to that body of knowledge. It started with an ethnobotanic survey of the use of wild food plants in 10 selected rural villages and peri-urban dwellings in the Amathole District of the Eastern Cape. These rural areas were chosen because of the belief that there are still individuals who possess the wealth of traditional knowledge within those remote areas in addition to that the villages are surrounded by indigenous vegetation from which they could be harvesting some indigenous food plants. Furthermore, the relationship between people and plants are often clearer in indigenous/traditional societies since the link between production and consumption is more direct. Besides the survey, this research employed various methods including Inductively Coupled Argon (ICP) analyses of minerals and vitamins, determination of phytochemicals and antioxidant/bio-activity that of, higher performance liquid chromatography (HPLC) determination of other vitamins, assessment of proximate and anti-nutrient compositions of raw and cooked samples of plants, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDXS) to look into the micro-morphology of leaves for details that might have a bearing in the nutrient composition of the wild edible vegetables. This was done with the aim to explore and highlight the wild-food-plant base of indigenous people, to investigate the nutritional value of the selected frequently consumed wild vegetables and to recommend ways of educating people on the value of such plants and the need to promote their continued sustainable use as well as preservation of them for the benefit of people who cannot afford a continuous nutritious meal particularly among rural communities. Twenty-five (25) indigenous wild food plants which included leafy vegetables, nuts and fruits species were identified as being arbitrarily gathered and utilised as food, of which seven wild leafy vegetable species were often mentioned as common among the 15 dwellings surveyed and most frequently consumed by the respondents. Two additional plants were also frequently used as flavoring and in their raw state respectively. Wild edible vegetables were mainly eaten boiled as ‘laxa’, mixed with maize meal as ‘imifino’, fried as relish ‘isishebo’ or raw for both snacking purposes and medicinal functions. Wild edible plant species in the Amathole District of the Eastern Cape-South Africa were documented with respect to their uses and knowledge or identification. Four indigenous wild vegetables (Chenopodium album, Solanum nigrum/nodiflorum, Amaranthus dubius and Urtica lobulata) frequently consumed by the indigenous communities in the study region were selected. All the plant species had a remarkably high content of pro-anthocyanidins (between 58.42 and 65.18 mg/g) and also exhibited high radical scavenging activity in vitro. S. nigrum and C. album were found to be rich sources of ascorbic acid, having 1.05mg/100g and 1.01mg/100g, respectively. The entire wild, traditionally edible plants contain reasonably good concentrations of riboflavin while U. lobulata was found to contain maximum amount of thiamine. All plant species were rich sources of minerals and vitamins (both water soluble and fat soluble). Appropriate cooking methods are to be used to enhance the bio-availability of vitamins and nutrients in general. Cooking generally improved the nutritive value in certain wild vegetables. However, some nutrients were drained away. For example micro-nutrient and anti-nutrient component in the ash were reduced in cooking. The EDXS analysis has shown that the indigenous, wild vegetables in the Amathole District of South Africa are excellent sources of minerals, while the mineral crystals present at the level of the mesophyll of the indigenous wild vegetables were probably mixtures of calcium oxalate, calcium sulphate and silica. Saponin, tannins, oxalates, phytates and alkaloids are present in all the indigenous wild vegetables, but in minimal safe quantities. Nutritional analysis of some wild food plants demonstrates that in many cases the nutritional quality of the plants is comparable and in some cases even superior to domesticated exotic varieties. Knowledge about gathering and use of some wild food species is common among the rural dwellers. However, most uses are known by few elderly informants only. Education, awareness campaigns and revival of use of wild edible plants directed at the youth particularly is essential and this can be done through all forms of media. , Thesis (PhD) (Ethnobotany) -- University of Fort Hare, 2012
- Full Text:
- Date Issued: 2012
Reservoir rock preoperty and hydrocarbon potentieal in the offshore gamtoos and algoa basins, South Africa
- Authors: Mokoele, Salmina Phuti
- Date: 2022-07
- Subjects: Hydrocarbon reservoirs , South Africa -- Gamtoos River , Gamtoos Estuary (South Africa)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27981 , vital:71409
- Description: Various research methods were employed to evaluate reservoir rock properties and source rock maturity for hydrocarbon potential in the offshore Gamtoos and Algoa basins, including lithostratigraphy, facies analysis, petrography, geophysics, geochemistry and basin modelling. Sedimentary facies were identified in the Gamtoos Basin along with their inferred depositional systems, mainly from the synrift I and II successions. This was also supplemented by lithostratigraphic evaluation of 12 wells across the study area. Facies analysis was applied to describe different rock types with depositional signatures by using the following parameters: grain fabric/texture, primary sedimentary structures, and fossil contents. Different types of lithofacies and biofacies were recorded indicating variations in bioturbation from low to high intensities. The results revealed a total of 15 types of facies from five cores, which were further subdivided into 8 types of sandstones, 3 types of siltstones, 3 types of mudstones and 1 type of conglomerate. Furthermore, five facies associations FA1 to FA5 were recognized from core evaluation: hemipelagite facies association, fine-grained, thinly bedded heterolithic sandstone-mudstone facies association (low-density turbidity flows), medium to coarse grained massive sandstone facies association high-density turbidity flows, debrites hybrid facies association and coarse grained conglomerate facies association. In terms of lithostratigraphic sequence, they correspond with fine- to medium-grained massive sandstone units of the Ta division, horizontal laminated sandstone units of the Tb division, fine to medium grained wavy laminated sandstone units of the Tc division, parallel laminated siltstones intercalated with fine grained ripple and lenticular sandstones of the Tc to Td divisions and fine grained massive, bedded siltstone units of the Te division. Both the Gamtoos and Algoa offshore basins comprise wells with proven source rock presence. Results from geochemical evaluations have revealed the presence of significant quantities of Late Jurassic to Early Cretaceous (Kimmeridgian, Tithonian, Berriasian, Valanginian and Hauterivian) source rock intervals. The wells used for this research intersected a total of 25 source rocks across the various age groups with an average thickness of 70 m. Source rocks with hydrocarbon potentials were intersected at Kimmeridgian, Tithonian, Berriasian, Valanginian and Hauterivian successions. The source rocks indicate good to excellent quality of hydrocarbons with the potential to generate both oil to gas. For example, Tithonian source rock shows a tremendous petroleum generation potential with mostly type II (oil prone) and type II/III (oil to gas prone) kerogen. The data suggests that the Tithonian source rock was mainly deposited in marine depositional settings with planktons being the main source of kerogen. Some of the kerogen could have originated from limited quantities of algae (marine settings) and terrestrial plants. The source rock indicates a potential to generate variable hydrocarbons from oil, wet gas and dry gas. The Kimmeridgian and Tithonian source rocks range from main oil window to post gas mature zone. In the south-eastern part of the offshore Gamtoos Basin, deep marine shale source rocks were deposited between the Kimmeridgian and Tithonian age and these marine conditions continued throughout the synrift stage. The Algoa Basin indicates the deposition of deep-water shale source rocks resulting from a transgression period. The Berriasian source rock indicates a range in maturity from the early oil to gas windows in the Gamtoos graben between 126 Ma and present day. The source rock further shows a maximum transformation ratio of 100 percent at well Ha-D1 in the Gamtoos Basin. The Valanginian source rock indicates a range in maturity from early to late oil windows in the Algoa Basin with extremely low rates of transformation at a maximum of 24.67 percentage at well Hb-B1. The Hauterivian source rock dominantly plots within the early to main oil windows with vitrinite values between 0.6 and 0.8 percent. Results obtained from this research indicate the presence of moderate to good quality source rocks from the Kimmeridgian, Tithonian, Berriasian, Valanginian and Hauterivian. Majority of the source rocks have type III kerogen which is most likely to generate gas. The study area shows the presence of good quality source rocks with good petroleum generation potentials. The source rocks also show the ability to generate and expel hydrocarbons. The deeper sections of the grabens indicate high maturity levels with source rocks dominantly in the gas and late oil windows while the flanks are indicative of lower maturity stages between early and main oil windows. The best source rocks were mainly intersected and modelled from the synrift section while the upper transitional to drift sections indicate good quality reservoir rocks. The upper sections of the study area show a tremendous improvement in the quality of the reservoirs with porosity levels recorded to be up to 26 percent. The porosity levels increase up to 17 percent at well Ha-B2. This generally improved the potential for good reservoirs in the area from what has been intersected by the wells to the entire study area with the presence of effective traps and seals. The influence of hydrothermal alteration and chlorite cementation is quite low at these shallower sequences which further improved the quality of these reservoirs. Some of the sandstones intersected from the synrift sections range from very fine to coarse grained in texture with very low permeability and porosity due to extensive carbonate cementation, and also affected by hydrothermal alteration resulted from the extensive faulting in the area. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-07
- Authors: Mokoele, Salmina Phuti
- Date: 2022-07
- Subjects: Hydrocarbon reservoirs , South Africa -- Gamtoos River , Gamtoos Estuary (South Africa)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27981 , vital:71409
- Description: Various research methods were employed to evaluate reservoir rock properties and source rock maturity for hydrocarbon potential in the offshore Gamtoos and Algoa basins, including lithostratigraphy, facies analysis, petrography, geophysics, geochemistry and basin modelling. Sedimentary facies were identified in the Gamtoos Basin along with their inferred depositional systems, mainly from the synrift I and II successions. This was also supplemented by lithostratigraphic evaluation of 12 wells across the study area. Facies analysis was applied to describe different rock types with depositional signatures by using the following parameters: grain fabric/texture, primary sedimentary structures, and fossil contents. Different types of lithofacies and biofacies were recorded indicating variations in bioturbation from low to high intensities. The results revealed a total of 15 types of facies from five cores, which were further subdivided into 8 types of sandstones, 3 types of siltstones, 3 types of mudstones and 1 type of conglomerate. Furthermore, five facies associations FA1 to FA5 were recognized from core evaluation: hemipelagite facies association, fine-grained, thinly bedded heterolithic sandstone-mudstone facies association (low-density turbidity flows), medium to coarse grained massive sandstone facies association high-density turbidity flows, debrites hybrid facies association and coarse grained conglomerate facies association. In terms of lithostratigraphic sequence, they correspond with fine- to medium-grained massive sandstone units of the Ta division, horizontal laminated sandstone units of the Tb division, fine to medium grained wavy laminated sandstone units of the Tc division, parallel laminated siltstones intercalated with fine grained ripple and lenticular sandstones of the Tc to Td divisions and fine grained massive, bedded siltstone units of the Te division. Both the Gamtoos and Algoa offshore basins comprise wells with proven source rock presence. Results from geochemical evaluations have revealed the presence of significant quantities of Late Jurassic to Early Cretaceous (Kimmeridgian, Tithonian, Berriasian, Valanginian and Hauterivian) source rock intervals. The wells used for this research intersected a total of 25 source rocks across the various age groups with an average thickness of 70 m. Source rocks with hydrocarbon potentials were intersected at Kimmeridgian, Tithonian, Berriasian, Valanginian and Hauterivian successions. The source rocks indicate good to excellent quality of hydrocarbons with the potential to generate both oil to gas. For example, Tithonian source rock shows a tremendous petroleum generation potential with mostly type II (oil prone) and type II/III (oil to gas prone) kerogen. The data suggests that the Tithonian source rock was mainly deposited in marine depositional settings with planktons being the main source of kerogen. Some of the kerogen could have originated from limited quantities of algae (marine settings) and terrestrial plants. The source rock indicates a potential to generate variable hydrocarbons from oil, wet gas and dry gas. The Kimmeridgian and Tithonian source rocks range from main oil window to post gas mature zone. In the south-eastern part of the offshore Gamtoos Basin, deep marine shale source rocks were deposited between the Kimmeridgian and Tithonian age and these marine conditions continued throughout the synrift stage. The Algoa Basin indicates the deposition of deep-water shale source rocks resulting from a transgression period. The Berriasian source rock indicates a range in maturity from the early oil to gas windows in the Gamtoos graben between 126 Ma and present day. The source rock further shows a maximum transformation ratio of 100 percent at well Ha-D1 in the Gamtoos Basin. The Valanginian source rock indicates a range in maturity from early to late oil windows in the Algoa Basin with extremely low rates of transformation at a maximum of 24.67 percentage at well Hb-B1. The Hauterivian source rock dominantly plots within the early to main oil windows with vitrinite values between 0.6 and 0.8 percent. Results obtained from this research indicate the presence of moderate to good quality source rocks from the Kimmeridgian, Tithonian, Berriasian, Valanginian and Hauterivian. Majority of the source rocks have type III kerogen which is most likely to generate gas. The study area shows the presence of good quality source rocks with good petroleum generation potentials. The source rocks also show the ability to generate and expel hydrocarbons. The deeper sections of the grabens indicate high maturity levels with source rocks dominantly in the gas and late oil windows while the flanks are indicative of lower maturity stages between early and main oil windows. The best source rocks were mainly intersected and modelled from the synrift section while the upper transitional to drift sections indicate good quality reservoir rocks. The upper sections of the study area show a tremendous improvement in the quality of the reservoirs with porosity levels recorded to be up to 26 percent. The porosity levels increase up to 17 percent at well Ha-B2. This generally improved the potential for good reservoirs in the area from what has been intersected by the wells to the entire study area with the presence of effective traps and seals. The influence of hydrothermal alteration and chlorite cementation is quite low at these shallower sequences which further improved the quality of these reservoirs. Some of the sandstones intersected from the synrift sections range from very fine to coarse grained in texture with very low permeability and porosity due to extensive carbonate cementation, and also affected by hydrothermal alteration resulted from the extensive faulting in the area. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-07
Effects of social and ecological factors on cattle grazing strategies in semi-arid communal rangelands of the Eastern Cape Province, South Africa
- Moyo, Bethwell (https://orcid.org/0000-0001-7524-9028)
- Authors: Moyo, Bethwell (https://orcid.org/0000-0001-7524-9028)
- Date: 2009-09
- Subjects: Communal rangelands--South Africa--Eastern Cape , Grazing--South Africa--Eastern Cape , Range Management--South Africa--Eastern Cape South Africa Eastern Cape
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/25461 , vital:64279
- Description: Communal rangelands are the main source of livestock feed for resource poor communal farmers. They are characterized by heavy stocking and poor management which is perceived to be the cause of the prevalent degradation hence the incessant calls for introduction of rotational grazing. Rotational grazing has been associated with improved rangeland condition and animal performance in commercial farms, hence the call that it needs to be introduced in communal areas. Management of communal rangelands within the rotational grazing context requires some fundamental understanding of the relationship between current rangeland use, socio-economic and ecological factors determining the present use of these areas. The objective of this study was to assess how historic tenure and patterns of use have influenced grazing practices and institutional structures, and to identify institutional and ecological factors determining present grazing strategies. Focus group discussions and questionnaire surveys in 11 communities revealed that villagers consider fences and paddocks as the best intervention to improve range management. Furthermore, it was shown that lack of strong local-level institutions, little or no knowledge of veld management, absence of rules and lack of seasonal restrictions on rangeland resource use are additional constraints that need to be considered for any rotational grazing intervention to be embraced. Communal areas vary in household head profiles, and this affects the livestock ownership patterns, which indirectly influences rangeland management. The fact that most of the income for communal area people is from state grants, makes farming secondary and the attention put on rangeland management would therefore be minimal. At present the weak local level institutions would therefoe make any plans to introduce rotational grazing difficult. Communal area grazing strategies are further influenced by rangeland heterogeneity caused by different factors. To understand these factors, the relationship between vegetation parameters in different patches and associated soil parameters was examined. Heterogeneity due to seasonal variation in the biomass of herbaceous vegetation was observed at Magwiji‘s sweetveld, with frequently selected patches having a significantly (p < 0.05) higher biomass in autumn (791 kg ha-1) and winter (528 kg ha-1), while in summer and spring there was no significant (p > 0.05) difference in biomass between frequently selected and less selected patches. The present situation in which communal areas support large livestock populations under continuous grazing is due to the fact that cattle would adjust to changes in forage availability by seeking higher biomass patches in times of forage scarcity as observed in Magwiji. At the coastal forest thornveld of Mnyameni the Canonical Correspondence Analysis (CCA) showed that the first axis was significantly correlated with soil organic carbon (r = -1, p < 0.05). Furthermore, the species that were significantly correlated with the first axis were Cynodon dactylon and Pennisetum clandestinum. These species were mainly found in sites that were preferred in April and June. At the sourveld of Upper Mnxe the first axis was significantly correlated with soil pH (r = 0.9, p < 0.05). At this rangeland, sites selected in June were associated with alkaline soils; characterized by a history of human settlement and dominated by Eragrostis superba and Heteropogon contortus. Soil electrical conductivity (EC) separated species (r = 0.9; p < 0.05) along the first axis at Magwiji, with mountain top sites selected in April and June having low EC and dominated by Digitaria eriantha, Eragrostis superba and Andropogon appendiculatus. Rangeland heterogeneity is caused by various factors, ranging from human disturbance to topography. These factors have an effect on the soil properties, and therefore, vegetation and thus lead to the observed heterogeneity which shapes the utilization patterns of these rangelands, and hence their continued support of large populations of livestock. To understand the effects of seasonal and spatial variation in resource use pattern and implications on range management, differences in cattle activity patterns in relation to veld type, season, daytime, management type (kraaling) and forage quality were examined. Seasonal activity patterns were only significant at Upper Mnxe (p < 0.05), with percent of time spent grazing (77 percent), resting (35 percent) and walking (24 percent) being higher in April, November and June respectively. , Thesis (PHD) -- Faculty of Science and Agriculture, 2009
- Full Text:
- Date Issued: 2009-09
- Authors: Moyo, Bethwell (https://orcid.org/0000-0001-7524-9028)
- Date: 2009-09
- Subjects: Communal rangelands--South Africa--Eastern Cape , Grazing--South Africa--Eastern Cape , Range Management--South Africa--Eastern Cape South Africa Eastern Cape
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/25461 , vital:64279
- Description: Communal rangelands are the main source of livestock feed for resource poor communal farmers. They are characterized by heavy stocking and poor management which is perceived to be the cause of the prevalent degradation hence the incessant calls for introduction of rotational grazing. Rotational grazing has been associated with improved rangeland condition and animal performance in commercial farms, hence the call that it needs to be introduced in communal areas. Management of communal rangelands within the rotational grazing context requires some fundamental understanding of the relationship between current rangeland use, socio-economic and ecological factors determining the present use of these areas. The objective of this study was to assess how historic tenure and patterns of use have influenced grazing practices and institutional structures, and to identify institutional and ecological factors determining present grazing strategies. Focus group discussions and questionnaire surveys in 11 communities revealed that villagers consider fences and paddocks as the best intervention to improve range management. Furthermore, it was shown that lack of strong local-level institutions, little or no knowledge of veld management, absence of rules and lack of seasonal restrictions on rangeland resource use are additional constraints that need to be considered for any rotational grazing intervention to be embraced. Communal areas vary in household head profiles, and this affects the livestock ownership patterns, which indirectly influences rangeland management. The fact that most of the income for communal area people is from state grants, makes farming secondary and the attention put on rangeland management would therefore be minimal. At present the weak local level institutions would therefoe make any plans to introduce rotational grazing difficult. Communal area grazing strategies are further influenced by rangeland heterogeneity caused by different factors. To understand these factors, the relationship between vegetation parameters in different patches and associated soil parameters was examined. Heterogeneity due to seasonal variation in the biomass of herbaceous vegetation was observed at Magwiji‘s sweetveld, with frequently selected patches having a significantly (p < 0.05) higher biomass in autumn (791 kg ha-1) and winter (528 kg ha-1), while in summer and spring there was no significant (p > 0.05) difference in biomass between frequently selected and less selected patches. The present situation in which communal areas support large livestock populations under continuous grazing is due to the fact that cattle would adjust to changes in forage availability by seeking higher biomass patches in times of forage scarcity as observed in Magwiji. At the coastal forest thornveld of Mnyameni the Canonical Correspondence Analysis (CCA) showed that the first axis was significantly correlated with soil organic carbon (r = -1, p < 0.05). Furthermore, the species that were significantly correlated with the first axis were Cynodon dactylon and Pennisetum clandestinum. These species were mainly found in sites that were preferred in April and June. At the sourveld of Upper Mnxe the first axis was significantly correlated with soil pH (r = 0.9, p < 0.05). At this rangeland, sites selected in June were associated with alkaline soils; characterized by a history of human settlement and dominated by Eragrostis superba and Heteropogon contortus. Soil electrical conductivity (EC) separated species (r = 0.9; p < 0.05) along the first axis at Magwiji, with mountain top sites selected in April and June having low EC and dominated by Digitaria eriantha, Eragrostis superba and Andropogon appendiculatus. Rangeland heterogeneity is caused by various factors, ranging from human disturbance to topography. These factors have an effect on the soil properties, and therefore, vegetation and thus lead to the observed heterogeneity which shapes the utilization patterns of these rangelands, and hence their continued support of large populations of livestock. To understand the effects of seasonal and spatial variation in resource use pattern and implications on range management, differences in cattle activity patterns in relation to veld type, season, daytime, management type (kraaling) and forage quality were examined. Seasonal activity patterns were only significant at Upper Mnxe (p < 0.05), with percent of time spent grazing (77 percent), resting (35 percent) and walking (24 percent) being higher in April, November and June respectively. , Thesis (PHD) -- Faculty of Science and Agriculture, 2009
- Full Text:
- Date Issued: 2009-09