Theses and Dissertations

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    Assessing drought impacts on riparian vegetation and local community adaptation: A case of Buffalo River Catchment, Eastern Cape province, South Africa
    (University of Fort Hare, 2023) Mpanyaro, Zolisanani; Kalumba, A.M.; Zhou, L.
    River catchments are vulnerable to drought events that significantly affect the ecosystem and the livelihoods of local communities, especially in water-scarce countries like South Africa. The significance of the Buffalo River catchment lies in its ecological value and the vital role it plays in supporting local communities. Despite the catchment's importance, there is a notable lack of documented evidence on drought effects in the area, underscoring the need for this research. Accordingly, the study assessed the impacts of drought on riparian vegetation and local communities’ adaptation strategies (1990 to 2020). To this end, the study utilised Landsat imagery, various indices (NDVI, TDVI, MNDWI), and the Standardized Precipitation Index (SPI), along with semi-structured questionnaires. The findings indicated that drought events resulted in precipitation variability (SPI 6 and 12 months), and a decline in river discharge (R² = 0.0235) with a moderately positive correlation (r = 0.77) between precipitation and water drainage. These results indicate adverse effects on riparian vegetation, leading to substantial challenges for local communities that rely on these resources. Local communities relying on riparian resources have faced significant disruptions, such as reduced agricultural productivity, limited water access, and various socio-economic challenges due to drought. As a result, the local community in the Buffalo River catchment has devised various adaptation strategies to drought impacts. The communities have experienced reduced agricultural productivity, limited water access, and other socio-economic difficulties due to drought. In response, they adopted several adaptation strategies, such as rainwater harvesting (65%), water reuse (36%), livelihood diversification (20%) conservation (12%), and alternative water sources (6%). The significance of this research lies in its potential to guide policymakers in developing community-based adaptation strategies, which could enhance the resilience and sustainability of river ecosystems in drought-prone areas.
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    Assessing the extent and impacts of illegal sand mining along the Wild Coast Zone of the Amathole District in the Eastern Cape province, South Africa
    (University of Fort Hare, 2024) Dandala, Mzikayise Colemand; Nel, W.; Kalumba, A.M.
    Sand mining is widespread, and its practice is increasing in developing and developed nations. However, the increased demand for sand has led some communities to mine sand illegally. Illegal sand mining brings irreversible environmental damage, and the physical and environmental effects of sand mining have developed into crises that often result in changes in land use dynamics. The Wild Coast zone of South Africa is recognised as an international biodiversity hotspot. Therefore, assessing the extent and impacts of illegal sand mining in this biodiversity hotspot is crucial for guiding environmental planning. However, traditional methods for monitoring illegal sand mining are time-consuming and costly. This study employed a monitoring and modelling spatiotemporal approach, which is non-destructive, costeffective, covers larger areas, and is a time-saving alternative to conventional methods. The research objectives were: (i) to evaluate the spatial and temporal trends of illegal sand mining (i.e., pit size) along the coastal zone from Kei River mouth to Lubanzi River mouth over the last 22 years (2000 – 2022) and (ii) to assess the impact of illegal sand mining activities on the landscape dynamics (i.e., land use change and vegetation cover change) in the study area. Aerial images and field surveys were used to assess the extent of illegal sand mining over the last few years. Additionally, 30-meter resolution images of Landsat from 2000 to 2022 were used to assess land cover and vegetation changes. The comprehensive analysis of illegal sand mining activities along the Eastern Cape coast from 2000 to 2022 has provided valuable insights into the escalating challenges of unauthorised extraction. The study identified a minimum of 24 illegal sand mining sites, with evidence indicating a significant growth in illegal sand mining activities over the observed period. The spatial extent of sand pits has expanded, reflecting the increasing demand for construction materials driven by rapid population growth. The physical damage caused by illegal sand mining was observed across most areas, with noticeable aftereffects such as the creation of sand pits and dumping. These findings underscore the urgency of addressing the drivers behind the growth of illegal sand mining, particularly the need for stronger legislation and law enforcement to curb unauthorised extraction. The assessment of the impact of illegal sand mining on landscape dynamics revealed significant changes in land use patterns, particularly in the conversion of vegetated lands to bare soil. The transition from other vegetation to bare soil highlights the early stages of environmental degradation resulting from sand mining activities. Additionally, the decline in forest and water areas underscores the loss of critical ecosystems along the coastal zone. This study highlights the pressing need for comprehensive regulatory measures and stakeholder collaboration to address the growing threat of illegal sand mining. By understanding sand mining activities' spatial and temporal trends and their impact on landscape dynamics, policymakers can develop targeted interventions to safeguard coastal ecosystems and promote sustainable development in the Eastern Cape region and beyond.
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    Biological evaluation and semi-synthesis of Isolated compounds from (Syzygium aromaticum (L.) Merr. & Perry) Buds
    (University of Fort Hare, 2014) Sibusiso, Rali; Oyedeji, O O; Nkeh-Chungag, B N
    Natural products play a fundamental role in modern drug discovery as they continue providing diverse bioactive lead compounds for new drug formulation. However, isolation of these valued compounds is problematic. On the other hand, the morbidity and mortality rates caused by non-communicable diseases are increasing with improved longevity. Thus, the study herein focused on the isolation of plant-derived compounds from Syzygium aromaticum and evaluated their biological properties. Syzygium aromaticum is a well-known plant which belongs to family Myrtaceae. Dried flower buds of S. aromaticum were subjected to sequential solvent extraction. The ethyl acetate extract (15.535 g) was subjected to column chromatography using a silica gel (0.063-0.200 mm) for isolation. This has led to the isolation of three distinct compounds that were identified as eugenol, maslinic acid (MA) and oleanolic acid (OA). The structural elucidation of these valued compounds was done using NMR, GC-MS, LC-MS, FT-IR and Mp. Further semi-synthesis of the oleanolic acid afforded acetate and ester OA-derived compounds with better solubility properties. All these compounds were evaluated for analgesic and anti-inflammatory properties. All tested compounds were administered at a dose of 40 mg/kg to both Wistar rats and Swiss mice. Significant (p<0.01) analgesic and anti-inflammatory properties are obtained for all compounds. The effects of eugenol in all experiment were better except in the thermal-induced pain or tail flick test. In the case of modified compounds, the formalin induced pain test disclosed that oleanane derived compounds confessed analgesic and anti-inflammatory effects better than OA, whereas, in tale flick test oleanolic acid proved superior analgesic effects compared to all its derivatives with the exception of the acetyl-derivative. Acute anti-inflammatory test showed that acetyl-derivatives were more active than other compounds. In conclusion, chromatographic techniques and semi-synthesise of oleanolic acid have resulted to several plant-derived compounds with analgesic and anti-inflammatory properties. The semi-synthesized compounds may serve as alternative drug candidates for new analgesic and anti-inflammatory drug formulation
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    Biological Evaluation and Semi-synthesis of Isolated Compounds from (Syzygium aromaticum (L.) Merr. & Perry) Buds.
    (University of Fort Hare, 2014) Rali, Sibusiso; Oyedeji, O.O.; Nkeh-Chungag, B.N.
    Natural products play a fundamental role in modern drug discovery as they continue providing diverse bioactive lead compounds for new drug formulation. However, isolation of these valued compounds is problematic. On the other hand, the morbidity and mortality rates caused by non-communicable diseases are increasing with improved longevity. Thus, the study herein focused on the isolation of plant-derived compounds from Syzygium aromaticum and evaluated their biological properties. Syzygium aromaticum is a well-known plant which belongs to family Myrtaceae. Dried flower buds of S. aromaticum were subjected to sequential solvent extraction. The ethyl acetate extract (15.535 g) was subjected to column chromatography using a silica gel (0.063-0.200 mm) for isolation. This has led to the isolation of three distinct compounds that were identified as eugenol, maslinic acid (MA) and oleanolic acid (OA). The structural elucidation of these valued compounds was done using NMR, GC-MS, LC-MS, FT-IR and Mp. Further semi-synthesis of the oleanolic acid afforded acetate and ester OA-derived compounds with better solubility properties. All these compounds were evaluated for analgesic and anti-inflammatory properties. All tested compounds were administered at a dose of 40 mg/kg to both Wistar rats and Swiss mice. Significant (p<0.01) analgesic and anti-inflammatory properties are obtained for all compounds. The effects of eugenol in all experiment were better except in the thermal-induced pain or tail flick test. In the case of modified compounds, the formalin induced pain test disclosed that oleanane derived compounds confessed analgesic and anti-inflammatory effects better than OA, whereas, in tale flick test oleanolic acid proved superior analgesic effects compared to all its derivatives with the exception of the acetyl- derivative. Acute anti-inflammatory test showed that acetyl-derivatives were more active than other compounds. In conclusion, chromatographic techniques and semi-synthesise of oleanolic acid have resulted to several plant-derived compounds with analgesic and anti-inflammatory properties. The semi-synthesized compounds may serve as alternative drug candidates for new analgesic and anti-inflammatory drug formulation derivative. Acute anti-inflammatory test showed that acetyl-derivatives were more active than other compounds. In conclusion, chromatographic techniques and semi-synthesise of oleanolic acid have resulted to several plant-derived compounds with analgesic and anti-inflammatory properties. The semi-synthesized compounds may serve as alternative drug candidates for new analgesic and anti-inflammatory drug formulation.
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    The characterization and electrochemistry of dye-sensitized solar cells
    (University of Fort Hare, 2013) Caga, Noloyiso; Meter, E L; Mamphweli, S N; Ajibade, P A
    In this study a presentation of the technology behind dye-sensitized solar cells, their design as well as the role of the different parts of the cell. The characterization of the cell is divided into four sections namely: the characterization of the paste required to make the TiO2 film and its optical properties using SEM-EDX and XRD analytical techniques; Analysis of the various absorptions of three Ru-based dyes using UV-Vis spectroscopy, Photoluminescence and Fourier Transform Infra-Red spectroscopy; the characterization and the analyses of the entire cell using Electrochemical Impedance Spectroscopy. The nine cells were prepared by examining RuL2(CN)2 , RuL2(NCS)2 or N3 dye and RuL2(NCS)2 TBA+ or N719 dye. [L = 2,2'-bipyridyl-4,4'-dicarboxylic acid ;TBA = tetra-butyl ammonium] were combined with three electrolytes namely: Z–150 , AN–50 and PN–50. The Iodolyte PN–50 is an iodide based low viscosity electrolyte with 50 mM of tri-iodide dissolved in a solvent called propionitrile (PN). The Iodolyte AN–50 is an iodide based low viscosity electrolyte with 50 mM of tri-iodide dissolved in a solvent called acetonitrile (AN). The Iodolyte Z–150 is an iodide based low viscosity electrolyte with 150 mM of tri-iodide dissolved in a solvent called 3-methoxypropionitrile (MPN) and with additives such an ionic liquid, malkylbenziimidazole and guanidine thiocyanate. A solar simulator was utilized with which the standard solar irradiation can be created in laboratory conditions. The fill factors as well as overall performance efficiencies of the these cells are quite low < 1.0%,.
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    Chemical constituents and biological studies of Tagetes minuta L. and Rauvolfia caffra sond
    (University of Fort Hare, 2015) Mlala, Sithenkosi
    Green plants synthesize and store a variety of biochemical compounds some of which are extractable as raw material and can be used for various scientific investigations. Different plant parts have different effects as they often contain different active chemical components. Consequently, specific parts or the whole plant can be used for various treatments. The aim of this study was to extract, isolate and characterize the biologically active volatile and non-volatile compounds from Tagetes minuta and Rauvolfia caffra respectively. Tagetes minuta plant was considered for extraction of essential oils using hydrodistillation method. Cis-β-ocimene (38.03 percent), caryophyllene oxide (18.04 percent), alloocimene (25.35 percent), isopropyl tetradecanoate (17.02 percent), cis-ocimene (38.14 percent) and trans-β-ocimene (37.03 percent) were the major components of essential oil analyzed from fresh stem, dried stem, fresh leaf, dried leaf, fresh flower and dried flower respectively. The volatile compounds were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography (GC). Essential oil of dried stem leaf and flower parts of T. minuta exhibit antioxidant activity as demonstrated by the DPPH and FRAP bioassays. Crude extracts were extracted from R. caffra stem bark using sequence of solvents namely n-hexane, dichloromethane, ethyl acetate, methanol and ethanol. A white powder, a β-sitosterol (non-volatile compound) was isolated by column chromatography from ethyl acetate fractions of R. caffra stem bark and identified on various spectroscopic techniques such as FTIR and (1D and 2D) NMR. Melting point was also determined to be a sharp 129-130 ºC. DCM, EA, MetOH and EtOH fractions as well as β-Sitosterol (compound SM/01), showed antioxidant activity when tested on DPPH, FRAP, total phenolic and flavonoid bioassays. This antioxidant activity might be due to the presence of hydroxyl groups in the compound and crude fractions. On the other hand, T. minuta’s essential oil showed high antioxidant activity when evaluated on the DPPH and FRAP bioassays, which can be attributed to the presence of oxygenated monoterpenes and sesquiterpenes known to act as free radical scavenging and reducing agents. The use of R. caffra stem bark extracts against hypertension and other diseases by traditional healers could be attributed to the presence of phytochemicals (polyphenols and flavonoids) with known health benefits. Thus, it is recommended that the plant should be exploited further using modern techniques involving separation and purification of compounds that can be used for drug formulation. This study supports the use of T. minuta and R. caffra as the potential natural antioxidant source to manage various diseases including hypertension.
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    Chemical constituents and biological studies of Tagetes minuta L. and Rauvolfia caffra Sond
    (University of Fort Hare, 2015) Mlala, Sithenkosi; Oyedeji, O O; Nkeh-Chungag, B N
    Consequently, specific parts or the whole plant can be used for various treatments. The aim of this study was to extract, isolate and characterize the biologically active volatile and non-volatile compounds from Tagetes minuta and Rauvolfia caffra respectively. Tagetes minuta plant was considered for extraction of essential oils using hydrodistillation method. Cis-β-ocimene (38.03%), caryophyllene oxide (18.04%), alloocimene (25.35 %), isopropyl tetradecanoate (17.02 %), cis-ocimene (38.14%) and trans-β-ocimene (37.03%) were the major components of essential oil analyzed from fresh stem, dried stem, fresh leaf, dried leaf, fresh flower and dried flower respectively. The volatile compounds were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography (GC). Essential oil of dried stem leaf and flower parts of T. minuta exhibit antioxidant activity as demonstrated by the DPPH and FRAP bioassays. Crude extracts were extracted from R. caffra stem bark using sequence of solvents namely n-hexane, dichloromethane, ethyl acetate, methanol and ethanol. A white powder, a β-sitosterol (non-volatile compound) was isolated by column chromatography from ethyl acetate fractions of R. caffra stem bark and identified on various spectroscopic techniques such as FTIR and (1D and 2D) NMR. Melting point was also determined to be a sharp 129-130 ºC. DCM, EA, MetOH and EtOH fractions as well as β-Sitosterol (compound SM/01), showed antioxidant activity when tested on DPPH, FRAP, total phenolic and flavonoid bioassays. This antioxidant activity might be due to the presence of hydroxyl groups in the compound and crude fractions. On the other hand, T. minuta’s essential oil showed high antioxidant activity when evaluated on the DPPH and FRAP bioassays, which can be attributed to the presence of oxygenated monoterpenes and sesquiterpenes known to act as free radical scavenging and reducing agents. The use of R. caffra stem bark extracts against hypertension and other diseases by traditional healers could be attributed to the presence of phytochemicals (polyphenols and flavonoids) with known health benefits. Thus, it is recommended that the plant should be exploited further using modern techniques involving separation and purification of compounds that can be used for drug formulation. This study supports the use of T. minuta and R. caffra as the potential natural antioxidant source to manage various diseases including hypertension.
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    Chemical Constituents and Biological Studies of Tagetes minuta L. and Rauvolfia caffra Sond.
    (University of Fort Hare, 2015) Mlala, Sithenkosi; Oyedeji, O.O.; Nkeh-Chungag, B.N.
    Green plants synthesize and store a variety of biochemical compounds some of which are extractable as raw material and can be used for various scientific investigations. Different plant parts have different effects as they often contain different active chemical components. Consequently, specific parts or the whole plant can be used for various treatments. The aim of this study was to extract, isolate and characterize the biologically active volatile and non-volatile compounds from Tagetes minuta and Rauvolfia caffra respectively. Tagetes minuta plant was considered for extraction of essential oils using hydrodistillation method. Cis-β-ocimene (38.03%), caryophyllene oxide (18.04%), alloocimene (25.35 %), isopropyl tetradecanoate (17.02 %), cis-ocimene (38.14%) and trans-β-ocimene (37.03%) were the major components of essential oil analyzed from fresh stem, dried stem, fresh leaf, dried leaf, fresh flower and dried flower respectively. The volatile compounds were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography (GC). Essential oil of dried stem leaf and flower parts of T. minuta exhibit antioxidant activity as demonstrated by the DPPH and FRAP bioassays. Crude extracts were extracted from R. caffra stem bark using sequence of solvents namely n-hexane, dichloromethane, ethyl acetate, methanol and ethanol. A white powder, a β-sitosterol (non-volatile compound) was isolated by column chromatography from ethyl acetate fractions of R. caffra stem bark and identified on various spectroscopic techniques such as FTIR and (1D and 2D) NMR. Melting point was also determined to be a sharp 129-130 ºC. DCM, EA, MetOH and EtOH fractions as well as β-Sitosterol (compound SM/01), showed antioxidant activity when tested on DPPH, FRAP, total phenolic and flavonoid bioassays. This antioxidant activity might be due to the presence of hydroxyl groups in the compound and crude fractions. On the other hand, T. minuta’s essential oil showed high antioxidant activity when evaluated on the DPPH and FRAP bioassays, which can be attributed to the presence of oxygenated monoterpenes and sesquiterpenes known to act as free radical scavenging and reducing agents. The use of R. caffra stem bark extracts against hypertension and other diseases by traditional healers could be attributed to the presence of phytochemicals (polyphenols and flavonoids) with known health benefits. Thus, it is recommended that the plant should be exploited further using modern techniques involving separation and purification of compounds that can be used for drug formulation. This study supports the use of T. minuta and R. caffra as the potential natural antioxidant source to manage various diseases including hypertension.
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    Chemical transformations and phytochemical studies of bioactive components from extracts of Rosmarinus officinalis L
    (University of Fort Hare, 2010) Okoh, Omobola Oluranti; Sadimenko, A P; Afolayan, A J
    Variations in the yield, chemical composition, antibacterial, and antioxidant properties of the essential oils of Rosmarinus officinalis L. cultivated in Alice, Eastern Cape of South Africa over a period of 12 months using the solvent-free microwave extraction and traditional hydrodistillation methods were evaluated. The GC-MS analyses of the essential oils revealed the presence of 33 compounds with 1,8-cineole, a-pinene, camphor, verbenone, bornyl acetate and camphene constituting about 80 percent of the oils throughout the period of investigation, with the solvent-free microwave extraction method generally yielding more of the major components than the hydrodistillation method. Each of the major components of the oils varied in quantity and quality of yield at different periods of the year. The method of extraction and time of harvest are of importance to the quantity and quality of essential oil of Rosmarinus officinalis. Higher amounts of oxygenated monoterpenes such as borneol, camphor, terpene- 4-ol, linalool, a-terpeneol were present in the oil of SFME in comparison with HD. However, HD oil contained more monoterpene hydrocarbons such as a-pinene, camphene, β-pinene, myrcene, a-phellanderene, 1,8-cineole, trans- β-ocimene, γ-teprinene, and cis-sabinene hydrate than SFME extracted oil. Accumulation of monoterpene alcohols and ketones was observed during maturation process of Rosmarinus leaves. Quantitative evaluation of antibacterial activity, minimum inhibitory concentration values were determined using a serial microplate dilution method. The essential oils obtained using both methods of extraction were active against all the bacteria tested at a concentration of 10 mg mL-1. The minimum inhibitory concentrations for the SFME extracted oils ranged between 0.23 and 1.88 mg mL-1, while those of the HD extracted oils varied between 0.94 and 7.5 mg mL-1, thus suggesting that the oil obtained by solvent free microwave extraction was more active against bacteria than the oil obtained through hydrodistillation. The antioxidant and free radical scavenging activity of the obtained oils were tested by means of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH+) assay and β- carotene bleaching test. In the DPPH+ assay, while the free radical scavenging activity of the oil obtained by SFME method showed percentage inhibitions of between 48.8 percent and 67 percent, the HD derived oil showed inhibitions of between 52.2 percent and 65.30 percent at concentrations of 0.33, 0.50 and 1.0 mg mL-1, respectively. In the β-carotene bleaching assay, the percentage inhibition increased with increasing concentration of both oils with a higher antioxidant activity of the oil obtained through the SFME than the HD method. Thin layer chromatography (TLC) was used to analyze the chemical composition of the extracts using three eluent solvent systems of varying polarities i. e. CEF, BEA and EMW and sprayed with vanillin-sulfuric acid. The chemical composition of the different extracts was similar with the exception of methanol and water extracts which had only one or two visible compounds after treating with vanillin-spray reagent. To evaluate the number of antibacterial compounds present in the fractions, bioautography was used against two most important nosocomial microorganisms. S. aureus (Gram positive) and E. coli (Gram negative). Nearly all the crude serial extraction fractions contained compounds that inhibited the growth of E. coli. The hexane extract had the most lines of inhibition followed by ethyl acetate. Bioassay-guided fractionation against E. coli was used to isolate antibacterial compounds. The largest number of antibacterial compounds occurred in the hexane fraction. Furthermore we tried to complete the characterization by extracting and studying other biologically important plant metabolites such as phenolic compounds to evaluate the antioxidant capacity of Rosmarinus extracts.
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    Chemical transformations and phytochemical studies of bioactive components from extracts of rosmarinus officinalis L.
    (University of Fort Hare, 2010) Okoh, Omobola Oluranti
    Variations in the yield, chemical composition, antibacterial, and antioxidant properties of the essential oils of Rosmarinus officinalis L. cultivated in Alice, Eastern Cape of South Africa over a period of 12 months using the solvent-free microwave extraction and traditional hydrodistillation methods were evaluated. The GC-MS analyses of the essential oils revealed the presence of 33 compounds with 1,8-cineole, a-pinene, camphor, verbenone, bornyl acetate and camphene constituting about 80% of the oils throughout the period of investigation, with the solvent-free microwave extraction method generally yielding more of the major components than the hydrodistillation method. Each of the major components of the oils varied in quantity and quality of yield at different periods of the year. The method of extraction and time of harvest are of importance to the quantity and quality of essential oil of Rosmarinus officinalis. Higher amounts of oxygenated monoterpenes such as borneol, camphor, terpene- 4-ol, linalool, a-terpeneol were present in the oil of SFME in comparison with HD. However, HD oil contained more monoterpene hydrocarbons such as a-pinene, camphene, β-pinene, myrcene, a-phellanderene, 1,8-cineole, trans- β-ocimene, γ-teprinene, and cis-sabinene hydrate than SFME extracted oil. Accumulation of monoterpene alcohols and ketones was observed during maturation process of Rosmarinus leaves. Quantitative evaluation of antibacterial activity, minimum inhibitory concentration values were determined using a serial microplate dilution method. The essential oils obtained using both methods of extraction were active against all the bacteria tested at a concentration of 10 mg mL-1. The minimum inhibitory concentrations for the SFME extracted oils ranged between 0.23 and 1.88 mg mL-1, while those of the HD extracted oils varied between 0.94 and 7.5 mg mL-1, thus suggesting that the oil obtained by solvent free microwave extraction was more active against bacteria than the oil obtained through hydrodistillation. The antioxidant and free radical scavenging activity of the obtained oils were tested by means of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH+) assay and β- carotene bleaching test. In the DPPH+ assay, while the free radical scavenging activity of the oil obtained by SFME method showed percentage inhibitions of between 48.8 % and 67 %, the HD derived oil showed inhibitions of between 52.2 % and 65.30 % at concentrations of 0.33, 0.50 and 1.0 mg mL-1, respectively. In the β-carotene bleaching assay, the percentage inhibition increased with increasing concentration of both oils with a higher antioxidant activity of the oil obtained through the SFME than the HD method. Thin layer chromatography (TLC) was used to analyze the chemical composition of the extracts using three eluent solvent systems of varying polarities i. e. CEF, BEA and EMW and sprayed with vanillin-sulfuric acid. The chemical composition of the different extracts was similar with the exception of methanol and water extracts which had only one or two visible compounds after treating with vanillin-spray reagent. To evaluate the number of antibacterial compounds present in the fractions, bioautography was used against two most important nos ocomial microorganisms. S. aureus (Gram positive) and E. coli (Gram negative). Nearly all the crude serial extraction fractions contained compounds that inhibited the growth of E. coli. The hexane extract had the most lines of inhibition followed by ethyl acetate. Bioassay-guided fractionation against E. coli was used to isolate antibacterial compounds. The largest number of antibacterial compounds occurred in the hexane fraction. Furthermore we tried to complete the characterization by extracting and studying other biologically important plant metabolites such as phenolic compounds to evaluate the antioxidant capacity of Rosmarinus extracts.
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    Computational studies, synthesis and characterization of ruthenium (ii) anticancer complexes
    (University of Fort Hare, 2014) Adeniyi, Adebayo Azeez; Ajibade, P A
    This thesis is centred on the application of Ru-based complexes as a promising alternative to cis-platin in cancer chemotherapy. Cis-platin is known to be the most prescribed chemotherapy which has more than 70% application in cancer cases especially the testicular cancer. An insight is provided in Chapter One and Two into the literatures reports on the application of Ru(II)-based complexes in cancer chemotherapy. In order to address some of the pressing challenges in rational design of Ru-based anticancer complexes, section 3.3 and 3.4 deal with efforts to elucidate the complication of their chemistry and instability while in section 3.5 efforts are made to find solution to the lack of proper knowledge of their targets using different theoretical approaches as presented in Chapter Three. In addition to the theoretical study, this thesis also comprises of the synthesis of the bis-pyrazole derivatives type of ligands and the derivatives of their Ru(II)-based complexes as provided in Chapter Four and Five respectively. Also the computational methods were used to elucidate the structural and spectroscopic properties of the synthesised ligands and their Ru(II)-based complexes. The geometrical and electronic properties are studied in relation to the stability and the reported anticancer activities of Ru(II)-based complexes in section 3.3. In subsection 3.3.1, several quantum properties including the natural energy decomposition analysis (NEDA) and quantum theory of atoms in a molecule (QTAIM) are computed on three models of RAPTA-C complexes using DFT with hybrid functional and basis set with ECP and without ECP. The higher stability of Carbo-RAPTA-C and Oxalo-RAPTA-C over RAPTA-C comes from the lower exchange repulsion and higher polarization contributions to their stability which gives insight into experimental observation. A similar study was carried out in subsection 3.3.2 on half-sandwich Ru(II)-based anticancer complexes with 6-toluene and 6-trifluorotoluene.
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    Computational studies, synthesis and characterization of Ruthenium(ii) anticancer complexes.
    (University of Fort Hare, 2014) Adeniyi, Adebayo Azeez
    As demand for water grows in South Africa, alternative sources are actively being sought to augment conventional water supply. While domestic rainwater harvesting has been put forward as one such an alternative water supply, little information is available on whether harvested rainwater is safe for human use or even how local communities feel about using the water from such an alternative source. The SU team tested the chemical and microbial quality of rainwater collected from the rainwater tanks of 29 houses over six months. In addition, 68 households were interviewed to investigate the acceptance and perception on the use of the domestic rainwater harvesting tanks. The results obtained for the chemical analysis indicated that the rainwater quality was within potable, chemical standards. Metals, cations and anions that were analysed for in the harvested rainwater samples were all below the recommended drinking water guidelines. However, the microbial analysis showed that the presence of the following group of indicator organisms exceeded the recommended drinking water guidelines: total coliforms, Eneterocci, faecal coliforms, and heterotrophic bacteria. The presence of several opportunistic pathogens, including E.coli, Cryptosporidium and Salmonella, were also detected. In short, the water from the rainwater harvesting tanks in Kleinmond is not fit for human consumption, and prior treatment is required before the water source can be used for drinking purposes. The main causes of contamination are dirt and faeces (from birds and small animals) on the roof surface, which fall into the tank. Other sources of rainwater contamination include leaf debris and organic material washed into the tank, animals or birds that fall into uncovered tanks as well as breeding mosquitoes. It was found that many of the households placed their garbage bags on top of the tanks to protect them from being ripped open by stray dogs. These garbage bags could easily contaminate the rainwater, especially if the tanks are leaking or broken and/or the lid is absent. This general lack of awareness of contamination hazards highlights the importance of training users in the proper use and maintenance of the technology. It has been recommended that some form of pre-treatment be installed to make the rainwater safe for drinking. As a follow up to this part of the project, the SU team is now investigating the use of solar water pasteurisation and filtration systems for the treatment of harvested rainwater. Interestingly, the SU user survey indicated that the majority of community members of the Kleinmond Housing Scheme instinctively steered clear of using the water from their rainwater harvesting tanks for drinking purposes. About two-thirds of the respondents do not use the water in the tank for drinking, while by far the majority of those who use it for drinking do so only sometimes (24%). The majority of respondents who do drink the water pre-treat it first. One mother reported that her baby developed a rash after rainwater was used to bath him, while others said that drinking the water was ‘bad for your stomach’. The majority of respondents indicated that they use the harvested rainwater for household chores instead, such as laundry, cleaning, and gardening. One respondent was even applying his rainwater to help run his small car wash business. This thesis is centred on the application of Ru-based complexes as a promising alternative to cis-platin in cancer chemotherapy. Cis-platin is known to be the most prescribed chemotherapy which has more than 70% application in cancer cases especially the testicular cancer. An insight is provided in Chapter One and Two into the literatures reports on the application of Ru(II)-based complexes in cancer chemotherapy. In order to address some of the pressing challenges in rational design of Ru-based anticancer complexes, section 3.3 and 3.4 deal with efforts to elucidate the complication of their chemistry and instability while in section 3.5 efforts are made to find solution to the lack of proper knowledge of their targets using different theoretical approaches as presented in Chapter Three. In addition to the theoretical study, this thesis also comprises of the synthesis of the bis-pyrazole derivatives type of ligands and the derivatives of their Ru(II)-based complexes as provided in Chapter Four and Five respectively. Also the computational methods were used to elucidate the structural and spectroscopic properties of the synthesised ligands and their Ru(II)-based complexes. The geometrical and electronic properties are studied in relation to the stability and the reported anticancer activities of Ru(II)-based complexes in section 3.3. In subsection 3.3.1, several quantum properties including the natural energy decomposition analysis (NEDA) and quantum theory of atoms in a molecule (QTAIM) are computed on three models of RAPTA-C complexes using DFT with hybrid functional and basis set with ECP and without ECP. The higher stability of Carbo-RAPTA-C and Oxalo-RAPTA-C over RAPTA-C comes from the lower exchange repulsion and higher polarization contributions to their stability which gives insight into experimental observation. A similar study was carried out in subsection 3.3.2 on half-sandwich Ru(II)-based anticancer complexes with 6-toluene and 6-trifluorotoluene. The trifluorotoluene and the hydrated models are characterised with higher charge transfer, polarizability, synergistic effect of ligand fragments, stronger and higher HB interactions that support their reported experimental anticancer activities and the mechanism of their activation by hydrolysis. Also in the subsection 3.3.3, the factors that determine the stability and the effects of non-covalent interaction on the two models of these half-sandwich 6-arene ruthenium anticancer complexes and their respective hydrated forms were investigated using DFT method. Lastly in section 3.3, the subsection 3.3.4 deals with the intramolecular properties of five sets of ruthenium based anticancer complexes using DFT method. The spectroscopic and the non-linear optical properties of selected Ru(II) anticancer complexes are shown in Section 3.4. In subsection 3.2.1, DFT method was applied to study the thermodynamic and spectroscopic properties of three Ru-based complexes in order to give possible reasons for the reported experimental stability of complexes 1 and 2 with bidentate chelating ligands than complex 3. A further study was carried out in Subsection 3.4.2 where computational method was used to gain insight into the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Lastly in this section, subsection 3.2.3 deals with application of different density functional methods (DFT) to optimize and study the chemistry of five potential anticancer complexes in terms of their electronic, conductive and spectroscopic properties. The carboxylic and pyrazole units are found to significantly enhance the polarizabilities and hyperpolarizabilities of the complexes while the chloride only improves the polarity of the complexes. The possible targets of Ru(II)-based anticancer complexes are predicted using docking methods as presented in section 3.5 of this thesis. In subsection 3.5.1, the interactions of selected Ru(II)-based complexes with different cancer receptors are carried out using computational docking. The study focuses more on finding alternative protein targets other DNA for some Ru(II)-based complexes using computational docking. A further study on addressing the problem of the improper knowledge of of the targets of Ru-based anticancer complexes was carried out in subsection 3.5.2. Some promising anticancer complexes of Ru(II) such as RAPTA based complexes formulated as [Ru(η6-p-cymene)L2(pta)] and those with unusual ligands are docked against receptors using Autodock, Glide and Gold. Lastly in section 3.5, docking packages Molegro and Autodock were applied in subsection 3.5.3 to predict the anticancer activities of selected Ru(II) complexes against twelve anticancer targets. Introducing the quantum calculated atomic charges of the optimized geometries is found to significantly improve the docking predictions of these anticancer metallocompounds. In section 4.3-4.6, the spectroscopic and the geometric properties of ligands with pyrazole, methylpyrazole, bipyridine and phenanthroline derivatives were studied at both experimental and computational levels. The computational results are perfectly in agreement with the experimental results especially in terms of the spectroscopic properties. The spectroscopic analyses as well as the computed properties were used to establish the successful synthesis of the ligands. Many of the functional groups in these ligands are found to be Raman active which also help in their spectroscopic elucidation. Lastly in chapter five, the method used for the synthesis of forty Ru(II)-based complexes were presented with their experimental spectroscopic features being elucidated using theoretical methods. A very high correlation was observed between experimental and theoretical characterisation of the complexes which is an indication of successful synthesis of the complexes.
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    Copper dithiocarbamate complexes and copper sulfide nanoparticles : synthesis, characterization and antifungal studies
    (University of Fort Hare, 2015) Botha, Nandipha Loveness
    Six dithiocarbamate ligands were synthesized from anisidine, aniline, ethyl aniline, butyl amine, morpholine and piperidine and used to synthesize homoleptic copper(II) dithiocarbamate complexes. The ligands and their corresponding complexes were characterized by conductivity measurement, FTIR and UV-Vis spectroscopy. The ligands were further characterized using NMR spectroscopy. The electronic spectra of the complexes showed that the coordination geometries around the Cu2+ ion is four coordinate square planar. FTIR spectroscopic studies indicated that the dithiocarbamate ligands are bidentately coordinated to the copper ion through the sulfur atoms with the C-S stretching frequencies changing from two peaks in the ligands to single sharp peaks in the corresponding metal complexes. The complexes were used as single source precursors to synthesize copper sulfide nanoparticles. All the six complexes were thermolysed at 180 oC to prepare copper sulfide nanoparticles and three of them were further thermolysed at 120 oC to study the effects of temperature on size and shape of the nanoparticles. All the nanoparticles were characterized with UV-Vis, PL, XRD, TEM, SEM and EDX. The optical properties of the as-prepared CuS nanoparticles showed that they are quantum confined with absorption band edges that are blue shifted compared to bulk CuS and all the as-prepared CuS nanoparticles showed narrow emission curves. The XRD diffraction patterns were indexed to the hexagonal covellite CuS crystalline phase with estimated particle sizes of 15.8-23.24 nm. These sizes are significantly different from the values, 3.02-98.94 nm obtained from TEM studies. The TEM images also showed nanoparticles with varied shapes with some agglomerations. SEM micrographs showed that the morphologies of the nanoparticles are mostly smooth surfaces and EDX spectra analyses confirmed the formation of the nanoparticles. Thermolysis of three of the complexes at 120 oC confirmed that temperature do affect the optical and structural properties of the CuS nanoparticles. Only three complexes soluble in DMSO were screened for their antimicrobial activity. Three complexes C1, C4 and C5 were screened against four fungi organisms, namely: Candida rugosa, Candida neoformans, Candida albicans and Trychophyton mucoides. All the compounds were promising as shown by the minimum inhibitory concentrations determined. C5 was the most active compound against all the organisms. They were also screened against four bacteria organisms and they were all active but not as they were against fungi organisms.
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    Design and characterization of sodium alginate-based scaffolds for the treatment of burn wounds
    (University of Fort Hare, 2024) Ndlovu, Sindi Prescila; Aderibigbe, B.A.; Motaung, S.
    Burn injuries have a considerable impact on mortality and morbidity rates due to the systemic immune changes and increased infection risks that they cause. These factors hinder the healing process and allow microbial invasion, leading to prolonged hospital stays and increased mortality rates. In this study, sodium alginate-based membranes, topical gel, and nanofibers were prepared and evaluated as potential wound dressings that are affordable and effective for treating burn wounds, suggesting that they can also be accessible to low income individuals. The topical gels were prepared from sodium alginate (SA), Carbopol, Carboxymethyl cellulose (CMC), and polyethylene glycol (PEG). The gels were loaded with Capparis sepiaria extract to enhance their antibacterial efficacy. Membranes were designed from SA/Gum acacia/PVA/PF127 and loaded with Capparis sepiaria, and nanofibers were developed from SA/PVA/PLGA and loaded with Capparis sepiaria. The topical gels, membranes, and nanofibers were evaluated using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), and X-ray diffraction (XRD), which confirmed the successful preparation of these three classes of wound dressings. The Water Vapor Transmission Rate (WVTR) values of the membranes and nanofibers were in a range of 1654.73 ± 0.74 and 319.24 ± 9.82 g/m2.24h, respectively, which is suitable for application on burn wounds, preventing moisture accumulation and reducing the risk of infection. The viscosity of the topical gels was in the range of 12 ± 0-7720 ± 152.83 and 20 ± 9.78-5256 ± 61.10 cP at 50 and 100 rPM, respectively, revealing a thixotropic/pseudoplastic behaviour, indicating that they can be easily applied on the wound bed. The membranes were biodegradable, with good swelling behaviour, showing their capability to absorb excess wound exudate. The membrane’s mechanical properties were studied, and their tensile strength was suitable for dermal application without causing discomfort upon removal from the wound bed. The topical gels, membranes, and nanofibers scaffolds displayed superior antibacterial efficacy against some gram-positive and gram-negative bacteria strains compared to the employed commercial wound dressing in this study that are responsible for the chronicity of burn wounds, such as Pseudomonas aeruginosa, Enterococcus faecalis, Mycobacterium smegmatis, Escherichia coli, Enterobacter cloacae, Proteus vulgaris, and Staphylococcus aureus. These three wound dressings showed a non-toxic effect on the immortalized human keratinocyte cells (HaCaT) cells, with a % cell viability of more than 85%. Furthermore, the wound dressings' capability to promote blood clotting was significant. The non-toxic nature of the wound dressings supported significant cell adhesion, migration, and proliferation than the commercial wound dressing used in the study. The three classes of SA-based wound dressings (i.e., topical gels, membranes, and nanofibers) displayed superior biological properties than commercial wound dressing, revealing their potential application as wound dressings on burn wounds.
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    Development and in vitro biological evaluation of hybrid wound dressings as potential therapeutics for the treatment of infected wounds
    (University of Fort Hare, 2024) Kula, Hlalisa; Aderibigbe, B.A.; Motaung, S.
    Infected wounds are challenging to treat and are identified as the leading causes of global mortality and morbidity. Improper management can result in amputations if not properly treated with appropriate wound dressings. The mental health of wound patients is great and some of them suffer from post-traumatic stress disorder (PTSD) due to prolonged hospitalisation. The problem associated with the treatment of infected wounds is that most commercially available wound dressings fail to cater for the wounds by not protecting the wounds from microbial invasion, non-compatibility, and inability to accelerate the wound healing process. Biopolymers such as polyvinyl alcohol (PVA), Hydroxypropylmethylcellulose (HPMC), Carboxymethylcellulose (CMC), and Sodium alginate (SA) were explored for preparation of hydrocolloids (single and double-layer) and cryogels loaded with Capparis sepiaria extract (cs-PE). The wound dressings were characterized by FTIR, SEM, and XRD. The mechanical properties such as tensile strength, thickness, and folding endurance were also evaluated. The tensile strength of the hydrocolloids ranged between 0.346 ± 0.13 to 5.590 ± 0.52 MPa and cryogels were between 0.094 ± 0.03 – 12.261 ± 0.56 Mpa. The surface pH of the dressings was in the range of 4.0-6.8 and the Water Vapour Transmission Rate (WVTR) ranged from 1032 ±2.79 to 9480 ±0.002 g/m2 .day-1 . The prepared biopolymer-based wound dressings incorporated with Capparis sepiaria exhibited good antimicrobial activity. XRD showed the amorphous nature of the wound dressings and the absence of free drugs, revealing their inability to trigger skin irritation. The antibacterial activity, cytotoxicity and wound scratch healing assay results showed that the prepared hydrocolloids and cryogels are effective against selected species of bacteria that are common in infected wounds, non-toxic, induce haemostatic effect, and have excellent capability to promote skin cell migration and proliferation. These features make them potential wound dressings for treating infected wounds.
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    Development of a bench scale single batch biomass to liquid fuel facility
    (2013) Zhang, Yusheng
    The research described in this dissertation was motivated by the global demand for energy that is not dependent on coal, oil, natural gas and other non-renewable fossil fuels. The technology used in this project is related to the use of biomass to produce a viable alternative to conventional sources of fuel. A bench scale biomass to liquid (BTL) facility was built and tested. This produced results confirming the feasibility of the BTL process. The findings of the pilot study outlined in this dissertation justified the conclusion that the next step will be to expand the capacity and productivity of the BTL pilot plant to an industrial scale. Biomass comes from a variety of renewable sources that are readily available. In this case, the material used in the fixed bed biomass gasification facility to generate wood gas was agricultural and forestry waste, such as straw and woodchips. The gasifier had the capacity to produce up to 10 cubic metres/hr of gas with a carbon monoxide and hydrogen content of between 20–40% by volume, when it was operated at ambient pressure and with air as the oxidizer. The gas, produced at a temperature above700ºC, was cooled in a quench/water scrubber in order to remove most of the mechanical impurities (tars and water-soluble inorganic particles), condensed and dried with corn cobs before being compressed in cylinders at over 100 bar(g)for use in the Fischer-Tropsch Synthesis (FTS). The syngas was subjected further to a series of refining processes which included removal of sulphur and oxygen. The sulphur removal technology chose entailed applying modified activated carbon to adsorb H2S with the help of hydrolysis in order to convert organic sulphur impurities into H2Swhich reduced the sulphur content of the gas to less than 5ppbv. Supported cobalt catalyst (100 grams), were loaded into single-tube fixed bed FT reactor with an inner diameter of 50 mm. The reactor was fitted with a heating jacket through which, heated oil ran to cool the reactor during a normal reaction occurring at <250 ºC, while nitrogen was used in the heating jacket during reduction, which occurred at temperatures up ~350 ºC. The FTS reaction was carried out at different pressures and temperatures. Liquid and wax products were produced from the facility. The properties of the liquid and solid hydrocarbons produced were found to be the same as FT products from other feed stocks, such as natural gas and coal.
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    Development of a visible light active, photo-catalytic and antimicrobial nanocomposite of titanium dioxide and silicon dioxide for water treatment
    (University of Fort Hare, 2012) Mungondori, Henry Heroe; Tichagwa, L
    The aim of this study was to prepare composite materials based on titanium dioxide (TiO2) and silicon dioxide (SiO2), and to evaluate their photo-catalytic and antimicrobial properties. Carbon and nitrogen doped TiO2nano-particles were prepared via a sol gel synthesis, which is a simple hydrolysis and condensation technique. In situ doping was carried out using glucose and urea as carbon and nitrogen sources respectively. Doping increased the spectral response of titanium dioxide photo-catalyst, allowing it to utilise the visible region which is much wider than the UV region (about 40 % of the solar spectrum), thus making it a more efficient photo-catalyst. The carbon and nitrogen doped TiO2-SiO2nano-particles were immobilized on glass support material to allow for easy separation of the spent photo-catalyst after the photo-degradation process. Tetraethyl orthosilicate (TEOS) was employed as both a binder and precursor for silicon dioxide. A mixture of TiO2 and TEOS in a 1:1 ratio was allowed to polymerize on a glass support which had been treated with hydrofluoric acid to introduce OH groups. The prepared photo-catalytic material was characterized by FT-IR, XRD, DRS, TEM, EDX, and BET analyses. Carbon was found to be more effective as a dopant than nitrogen. It brought about a band gap reduction of 0.30 eV and a BET surface area of 95.4 m2g-1 on the photo-catalyst as compared to a gap reduction of 0.2 eV and surface area of 52.2 m2g-1 for nitrogen doped TiO2. On the other hand, introduction of SiO2 allowed utilization of visible light by the TiO2-SiO2 nano-composite leading to an improved rate of photo-degradation of both methyl orange and phenol red. However, the immobilization of TiO2 on support material made it less effective towards inactivation of E. coli ATCC 25922 bacterial cells when compared to powdered TiO2 which was able to inactivate about 98 % of the bacterial cells within an hour of treatment.
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    Ethanol production from lignocellulosic sugarcane leaves and tops
    (2014) Dodo, Charlie
    Various methods for the production of bioethanol using different feedstocks have been researched on. In most work on bioethanol synthesis from sugar cane, tops and leaves have been regarded as waste and generally removed and thrown away. In this work, lignocellulosic sugarcane leaves and tops were not discarded but instead used as biomass to evaluate their hydrolyzate content. The leaves and tops were hydrolysed using different methods, namely concentrated acid, dilute acid pre-treatment with subsequent enzyme hydrolysis and compared with a combination of oxidative alkali pretreatment and enzyme hydrolysis. Subsequent fermentation of the hydrolyzates into bioethanol was done using the yeast saccharomyces cerevisae. Acid hydrolysis has the problem of producing inhibitors, which have to be removed and this was done using overliming with calcium hydroxide and compared to sodium hydroxide neutralization. Oxidative alkali pre-treatment with enzyme hydrolysis gave the highest yields of fermentable sugars of 38% (g/g) using 7% (v/v) peroxide pre-treated biomass than 36% (g/g) for 5% (v/v) with the least inhibitors. Concentrated and dilute acid hydrolysis each gave yields of25% (g/g) and 22% (g/g) yields respectively although for acid a neutralization step was necessary and resulted in dilution. Alkaline neutralization of acid hydrolyzates using sodium hydroxide resulted in less dilution and loss of fermentable sugars as compared to overliming. Higher yields of bioethanol, 13.7 (g/l) were obtained from enzyme hydrolyzates than 6.9 (g/l) bioethanol from dilute acid hydrolyzates. There was more bioethanol yield 13.7 (g/l) after 72h of fermentation with the yeast than 7.0 (g/l) bioethanol after 24h. However, the longer fermentation period diminishes the value of the increase in yield by lowering the efficiency of the process.
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    Ethanol production from lignocellulosic sugarcane leaves and tops
    (University of Fort Hare, 2014) Dodo, Charlie Marembu; Manene, N; Tichagwa, L
    Various methods for the production of bioethanol using different feedstocks have been researched on. In most work on bioethanol synthesis from sugar cane, tops and leaves have been regarded as waste and generally removed and thrown away. In this work, lignocellulosic sugarcane leaves and tops were not discarded but instead used as biomass to evaluate their hydrolyzate content. The leaves and tops were hydrolysed using different methods, namely concentrated acid, dilute acid pre-treatment with subsequent enzyme hydrolysis and compared with a combination of oxidative alkali pretreatment and enzyme hydrolysis. Subsequent fermentation of the hydrolyzates into bioethanol was done using the yeast saccharomyces cerevisae. Acid hydrolysis has the problem of producing inhibitors, which have to be removed and this was done using overliming with calcium hydroxide and compared to sodium hydroxide neutralization. Oxidative alkali pre-treatment with enzyme hydrolysis gave the highest yields of fermentable sugars of 38% (g/g) using 7% (v/v) peroxide pre-treated biomass than 36% (g/g) for 5% (v/v) with the least inhibitors. Concentrated and dilute acid hydrolysis each gave yields of25% (g/g) and 22% (g/g) yields respectively although for acid a neutralization step was necessary and resulted in dilution. Alkaline neutralization of acid hydrolyzates using sodium hydroxide resulted in less dilution and loss of fermentable sugars as compared to overliming. Higher yields of bioethanol, 13.7 (g/l) were obtained from enzyme hydrolyzates than 6.9 (g/l) bioethanol from dilute acid hydrolyzates. There was more bioethanol yield 13.7 (g/l) after 72h of fermentation with the yeast than 7.0 (g/l) bioethanol after 24h. However, the longer fermentation period diminishes the value of the increase in yield by lowering the efficiency of the process.
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    Flow unit determination of the upper shallow marine sandstone resevoirs in the Bredasdorp Basin, offshore South Africa
    (University of Fort Hare, 2024) Mudau, Ndamulelo; Magoba, M.; Opuwari, M.
    This study comprehensively analyses reservoir flow units and distribution in four wells (E-E1, E-S3, E-S5, and E-W1) of the lower Cretaceous upper shallow marine sandstone reservoirs in the Bredasdorp Basin, offshore South Africa. The study integrated multiple techniques, including the Stratigraphic Modified Lorenz Plot, Improved Stratigraphic Modified Lorenz Plot, Winland pore throat radius, Stratigraphic Flow Profile, and Flow Zone Indicator, to establish the spatial flow unit distribution of the upper shallow marine reservoirs. Analyses of 400 core plugs, 14 thin section slides, and 15 Scanning Electron Microscopy samples and core logging provided detailed insights into petrophysical properties and diagenetic minerals affecting the flow units within the reservoir. A comprehensive examination of gamma-ray logs and core samples identified a prominent glauconitic sandstone reservoir in the upper shallow marine formations. The conventional core analysis revealed substantial variability in porosity (0.3 % - 18 %, average 6.4 %) and permeability (0.008 - 170 mD, average 24.5 mD). Stratigraphic Modified Lorenz Plot Identified three flow units: barrier, baffle, and normal flow units, with storage capacity and flow capacity, ranging from 1.6 – 12.9 and 0.08 – 32.6, respectively. Improved Stratigraphic Lorenz Plot (ISMLP) results identified six flow unit types: barrier, semi-barrier, semi-conductor, conductor, superconductor, and fractured. Flow unit ranking indicated reservoir quality ranges from barrier/seal (0°- 15°) to fractured (75° - 85°). Pore throat radius (R35) results revealed diverse rock-type distributions from nanoporous to macroporous, ranging from 0.3 µm to 6.6 µm. These rock types indicated fair reservoir quality. Flow Zone Indicator (FZI) identified five distinct Hydraulic Flow Units (HFUs): HFU 1, HFU 2, HFU 3, HFU 4, and HFU 5, with values ranging from 0.19 µm to 28.7 µm, with an average value of 2.9 µm. Flow zone correlation revealed widespread low-flow zones and localized moderate-flow zones. Core logging analysis revealed distinct lithological characteristics among the reservoirs. Wells E-E1 and E-S3 comprise medium- to coarse-grained sandstones with rip-up clasts of claystone and siltstone, predominantly pyritic and glauconitic. In contrast, well E-S5 exhibits cross-bedded sandstones, fining upward with claystone clasts, pebble shaped lithic grains, and conglomerates formed from rounded gravel. E-W1 consists of fine- to medium-grained sandstones and conglomerates with scattered pebbles. Multiple facies were identified in each well's cored intervals, with well E-E1 containing five facies (A-E), wells E-S3 and E-S5 having four facies (A-D), and well E-W1 having three facies (A-C). Diagenetic minerals such as glauconite, pore-filling illite, smectite, and cementations (quartz overgrowth and calcite) significantly affected the baffle and barrier flow units. The results from this study will improve the understanding of flow unit distribution and reservoir heterogeneity in Bredasdorp Basin. It can also be used as input parameters for the 3D dynamic flow unit modeling of the upper shallow marine sandstones in this Basin.