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ItemStructural elucidation, antimicrobial, antioxidant, and toxicity of compounds from selected Ugandan medicinal plants used in treating bacterial skin infections(Makerere University, 2025)Many Ugandans rely heavily on medicinal plants for the treatment of bacterial skin infections. However, the efficacy of these medicinal plants for their pharmacological and phytochemical action are not known. The study aimed at evaluating the antibacterial, antioxidant, toxicity, and phytochemical composition of the extracts of Spermacoce princeae (K. Schum), Dolichopentas decora (S. Moore) and Rytigynia kigeziensis (De wild). The plant samples collected from Western region of Uganda and extracted by maceration sequentially using hexane, ethyl acetate, methanol, and distilled water. Antibacterial and antifungal activity of each extract and compound was carried out using an agar well diffusion and potato dextrose assay respectively against Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and, Klebsiella pneumonie. The toxicity of the extracts was assessed using healthy albino rats according to OCED guidelines 402 and 410. Antioxidant activity of extracts was carried out using 2,2-diphenyl-1-picryl-hydrazyl radical scavenging assay. Compounds were isolated using a combination of chromatographic techniques and their structures were elucidated using a combination of spectroscopic techniques. Phytochemical analysis of S. princeae extracts led to the isolation and identification of 11 compounds which included; quercetin (1), kaempferol-3-O-rutinoside (2), rutin (3), myo-Inositol (4), asperulosidic acid (5), hexadecanoic acid (6), β-sitosterol (7), stigmasterol (8), campesterol (9), ursolic acid (10), β-sitosterol glucoside (11). Two novel compounds (a benzophenone 18 and cyano-compound 20) were isolated and identified from extracts from D. decora in addition to squalene (13) and protocatechuic acid (19). Phytochemical analysis of R. kigeziensis extracts led to the isolation and identification 12 known compound that included; pomolic acid (23), 23- hydroxyursolic acid (24), rotundic acid (25), heptyl coumarate (31), vomifoliol (34) and five novel triterpenoids (27, 28, 29, 30 and 33). Compounds 10 and 2 showed antibacterial and antifungal activity against S. aureus, P. aeruginosa, C. albicans, and A. flavu with ZOI ≥ 10.0 ± 0.1 mm. Kaempferol-3-O-rutinoside (2) showed good antioxidant activity (IC50 = 64.81µg/ml) and good sun protection factor (SPF = 26.83). The aqueous extract of S. princeae was not toxic at 8000 and 10,000 mg/Kg. The selected medicinal plants possessed good antibacterial, antioxidant, and sun protection agents. The aqueous extract of S. princeae was generally nontoxic. The novel compounds may present a vital template in pursuit of alternative antibacterial, antioxidant and sun protection agents.
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ItemDeveloping experimental control method and simulation model for solar cookers with heat storage(Makerere University, 2025)The use of wood and fossils for cooking among others has led to global warming and deforestation. This necessitates the use of renewable energy sources. Solar energy is the only renewable energy source that is clean and freely available all over the earth's surface during sunny hours of the day. Due to its intermittent nature, its thermal energy has to be stored in thermal energy in Thermal Energy Storage (TES) systems for indirect solar cookers. The developed TES systems have some shortcomings like thermal stratification and low efficiency that need to be addressed. Thermal stratification is guaranteed in a TES system when thermally charged at a constant temperature. A mechanical thermostat has been developed to charge oil in a TES system at a constant temperature. This thermostat was composed of: a slider-valve, pneumatic cylinder, heating chamber and expansion system. This thermostat was tested by charging a 3-tank TES system. The 3-tank TES system was composed of a cold oil reservoir tank, a hot oil storage tank, a drainage tank and a cooking unit. A simulation model for charging an oil-based TES system with a forced thermal strati-_cation was developed and validated using experimental data. The results showed that the thermostat charging temperatures had oscillations which were reduced by lowering the ow rate by partially opening the valve along the oil pipe from the cold-oil reservoir to the thermostat. The 3-tank TES system was charged at an efficiency of 51.3% using the thermostat and later discharged through a cooking unit by boiling 0.5 liters of water at discharge efficiencies of 14.1%, 32.5% and 19.7% for the ow rates of 2.1, 2.8 and 6.5 g/s, respectively. These results also showed that 1 kg of rice that required 0.032 kWh could be cooked using 0.82-1.92 liters of oil at 200 _C. The developed 1D model had a mean absolute percentage error in the range 4.9%-8.2% and could study the effect of insulation and ow rate on the system thermal profiles.
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ItemFluvial geomorphology of the Turaco prospect, Semliki basin, south-western Uganda(Makerere university, 2025-08-14)Turaco Prospect was identified in the Semliki Basin located south of Lake Albert. Turaco-1, 2 and 3 wells were drilled by Heritage Oil and Gas Limited (HOGL) in 2002, 2004 and 2005 respectively and the location selected on the basis of a 2-D seismic dataset. Although the three (3) wells were largely unsuccessful, the Turaco-3 well which was drilled to a Total depth (TD) of 2960m encountered hydrocarbon bearing Formations. A 3-D seismic data was later acquired in 2005 over the Turaco Prospect area but was not significantly utilized to better understand the Prospect. This research utilized attributes derived from the 3-D seismic and well data that exists over the Turaco Prospect, RGB blending and geobody extraction to study the fluvial geomorphology of the area. The four (4) 3-D seismic attributes, namely; RMS amplitude, Sweetness, Variance and Envelope have been evaluated and used in the analysis of facies and depositional environment in the basin together with Gamma Ray well logs. Four seismic events or horizons were picked and interpreted. The choice of the seismic events was based on the quality of the seismic-well ties along with interpretive judgment on the reservoir targets that have been well defined bythe Turaco-1, 2 and 3 wells. The Formation s interpreted were the Nyaburogo, Oluka, Kakara and Kisegi. The seismic attribute maps for the different Formation s were generated using different extraction methods in petrel software; this was followed by RGB blending and geobody extractions to create maps for interpretation and analysis to identify seismic facies, depositional environment and their lateral variation. Eight (8) primary facies associations have been identified and interpreted. These are Crevasse Channels, Distributary Channels, Mouth Bars, Bifurcation Bars and Point Bars which are associated with Fluvial Environment as per the grouping and interpretation from Gamma Ray log interpretation, and Delta Front, Lower Delta Plain and Upper Delta Plain which are associated with the Delta and Lacustrine Environments also as per the grouping and interpretation from Gamma Ray log interpretation. The mapping and inference of facies from seismic attribute maps was entirely based on the variation in attribute values which is depicted by colors after RGB color blending. From the attribute maps, three sediment lithologies have been interpreted that is: sands, silts and clays
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ItemPhoto-catalytic degradation of microplastics in wastewater using Metal Modified Titanium (IV) oxide catalysts(Makerere University, 2025-06)Microplastics (MPs) are increasingly recognized as emerging environmental pollutants due to their ubiquitous distribution, persistence, and potential impacts on ecosystems and human health. These particles, resulting from the breakdown of larger plastic materials, are small enough to be ingested by organisms, often being mistaken for food. In addition to their physical presence, MPs act as vectors for other pollutants such as heavy metals and persistent organic pollutants, which can bioaccumulate and transfer through the food chain. Although wastewater treatment plants (WWTPs) serve as barriers to MPs entering aquatic ecosystems, they are not specifically designed for MP removal and can therefore serve as point sources of MP pollution in receiving water bodies. This study assessed a novel approach to MP remediation by employing metal-modified Titanium (IV) oxide (TiO₂) nanophotocatalysts activated under visible light. High-density polyethylene (HDPE) and polyethylene terephthalate (PET) microplastics were used as model polymers to optimize degradation conditions, which were subsequently applied to environmental MP samples. The photocatalysts were synthesized using the sol-gel method with vanadium (V), cobalt (Co), and molybdenum (Mo) as modifying metal ions, a combination not extensively studied in MP degradation research. Characterization of the materials was performed using X-ray diffraction (XRD) for crystal structure, scanning electron microscopy (SEM) for morphology, and UV- Vis spectrophotometry for optical properties. Metal modification with V, Co, and Mo resulted in complete transformation of TiO₂ to the anatase phase and narrowing of the band gap from 3.2 eV to 2.7 eV, enhancing its activity under visible light. Degradation was found to be pH-dependent: acidic conditions favored HDPE degradation, while neutral to alkaline conditions enhanced PET breakdown. Fourier-transform infrared spectroscopy (FTIR) revealed formation of carbonyl (C=O) and hydroxyl (OH) groups, indicating oxidative degradation. Visual observations under an optical microscope showed yellowing, cracking, and surface deformation of the MPs. An increase in chemical oxygen demand (COD) to 230.0 mg/L in treated samples confirmed the disintegration of MPs into smaller organic compounds. Significant mass reductions were observed after 200 hours of exposure, with environmental MP samples showing 83.0 to 91.7% degradation depending on the photocatalyst used. These results demonstrate the novel potential of visible-light-driven, metal-modified TiO₂ photocatalysis as an effective method for MP degradation in wastewater. The findings suggest that this method could be incorporated into existing WWTPs as an additional treatment step to enhance the removal of MPs from wastewater.
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ItemDevelopment of Zeolite/ BI2O3 nanocomposite for removal of Rhodamine B dye from wastewater(Makerere University, 2024)This study focused on the synthesis of a zeolite/bismuth oxide nanocomposite for the removal of Rhodamine B dye from wastewater. The synthesis of the nanocomposite was achieved through the sol-gel method, followed by thorough characterization using various techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy/energy dispersive X-ray spectrometry (SEM-EDS), X-ray diffraction (XRD), dynamic light scattering (DLS), point of zero charge determination, and surface resonance analysis. The optimization conducted through a batch process involved a comprehensive investigation into various parameters to assess their influence on Rhodamine B dye removal efficiency. The results revealed that the optimum conditions for maximum removal efficiency (100%) were achieved at pH 4, an initial dye concentration of 0.5 mg/L, an adsorbent dose of 0.55 g, a contact time of 10 minutes, and a temperature of 25 °C. The isotherm study revealed that the adsorption behaviour of Rhodamine B dye onto the zeolite/Bi2O3 nanocomposite followed the Freundlich Isotherm Model with a correlation coefficient (R2) value of 0.9953, suggesting a favourable adsorption process. Additionally, the kinetic model analysis indicated that the pseudo-second-order model best described the adsorption kinetics, implying a chemisorption mechanism. Furthermore, the thermodynamic analysis provided valuable insights into the spontaneous and endothermic nature of the adsorption process. The negative values of ΔG° indicated the feasibility and spontaneity of the adsorption, while the positive ΔH° indicated an endothermic nature. The negative value of ΔS° indicated a decrease in the randomness at the solid-liquid interface during the adsorption process. The zeolite/Bi2O3 nanocomposite was then used to test its efficiency in removing Rhodamine B dye from real wastewater samples. The percentage of Rhodamine B dye removed by zeolite/Bi2O3 nanocomposite was 98.12% of wastewater sample. This study, therefore, suggests that zeolite/Bi2O3 nanocomposite is a promising absorbent for the removal of Rhodamine B dye from aqueous solutions and wastewater samples.