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Now showing 1 - 5 of 253
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    Effectiveness of biosilica nanoparticles from eichhornia crassipes in the control of acanthoscelides obtectus
    (Makerere University, 2026) Babirye, Prudence Mary
    The widespread use of synthetic pesticides in post-harvest pest management has raised significant environmental and human health concerns due to their persistence, toxicity, and the development of resistant pest populations. These challenges have increased the need for sustainable pest control alternatives. Eichhornia crassipes, a silica-rich invasive aquatic plant from Lake Victoria, is a promising source of biosilica for biopesticide production. This study evaluated the effectiveness of biosilica nanoparticles synthesized from E. crassipes in the control of Acanthoscelides obtectus, a major post-harvest pest of common beans. Prior to biosilica synthesis, the moisture content, dry matter, ash content, and biosilica yield of the plant material were determined. The synthesized biosilica was characterized using UV–Visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM–EDX), X-ray Diffraction (XRD), and ImageJ particle size analysis. Bioassays were conducted on three bean varieties (Narobean 3, Kanyebwa, and Nambale) using biosilica concentrations ranging from 1.25 to 50 mg per 10 g of beans over a 15-day period. Leaves produced the highest biosilica yield (5.14 ± 0.04 g per 100 g dry biomass), followed by roots (4.42 ± 0.04 g) and stems (3.48 ± 0.04 g), with significant differences among plant parts (p < 0.05). FTIR confirmed the presence of characteristic Si–O–Si and Si–OH functional groups, while XRD showed broad diffraction humps around 2θ ≈ 19.94 –22.06°, indicating predominantly amorphous silica. SEM revealed irregular, porous, quasi-spherical particles, and EDX confirmed silicon and oxygen as the dominant elements. ImageJ analysis showed mean particle diameters of approximately 99.44 ± 20.90 nm (leaves), 100.02 ± 15.10 nm (stems), and 100.05 ± 16.83 nm (roots), confirming successful nanoscale synthesis. Bioassay results showed similar final mortality rates for biosilica derived from leaves (50.6 ± 2.5%), stems (50.6 ± 2.0%), and roots (49.8 ± 1.0%). One-way ANOVA indicated that neither the biosilica source nor bean variety significantly influenced final insect mortality (p > 0.05). The study demonstrates that E. crassipes is a viable renewable source of amorphous biosilica nanoparticles with potential application as an environmentally friendly biopesticides for post-harvest pest management.
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    Assessment of the effectiveness of biosilica nanoparticles from wheatstraw in the removal of Per- and Polyfluoroalkyl substances from wastewater.
    (Makerere University, 2026) Nabuuma, Josephine
    Conventional wastewater treatment processes are ineffective for the complete removal of per- and polyfluoroalkyl substances (PFASs), particularly short-chain compounds, necessitating the development of sustainable and efficient adsorbents. Wheat straw, an abundant but underutilised agricultural by-product, is a rich source of silica and offers potential for value-added production of biosilica adsorbents. In this study, cetyltrimethylammonium bromide (CTAB) templated silica (CTS) was synthesized from wheat straw and evaluated for the removal of PFASs from wastewater. Biosilica synthesis involved controlled ash generation, acid leaching, alkaline extraction, and sol-gel processing. Powder X-ray diffraction analysis showed a broad diffraction peak at 22° 2θ, indicating an amorphous structure. SEM analysis revealed irregular, agglomerated particles with rough and non-uniform surfaces, while EDX confirmed silicon and oxygen as the dominant elements, with minor carbon from residual surfactant fragments. FTIR analysis exhibited a prominent band at 1039 cm⁻¹, characteristic of Si–O–Si stretching in the siloxane network. Batch adsorption experiments were carried out to determine the effects of pH, adsorbent dosage, contact time, and initial PFAS concentration. Optimal conditions were pH 4, adsorbent dosages of 40 mg/L for PFOS and 50 mg/L for PFBA, PFBS, and PFOA, an initial PFAS concentration of 25 ng/L, and a contact time of 30 min. PFBA fitted both Langmuir (R² = 0.9916) and Freundlich (R² = 0.9914) models, while PFBS, PFOA, and PFOS followed the Freundlich model (R² = 0.9921–0.9986), suggesting multilayer adsorption. Adsorption efficiency increased with PFAS chain length and functional group strength with sulfonates showing higher removal than carboxylates, and the long chain PFASs were adsorbed more effectively than short chain analogues. All PFASs followed pseudo-second-order kinetics (R² = 0.9888–0.9977), indicating that chemisorption dominated the removal. Application to wastewater samples showed 78–92 % removal efficiency of the individual PFASs. These results showed that CTS from wheat straw can remove PFASs from wastewater and has potential for future water treatment application.
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    Delineation of petroleum plays in the offshore Lamu Basin, Southeast Kenya
    (Makerere University, 2026) Kennedy, Alpha
    Despite having evidence of a working petroleum system, the offshore Lamu Basin of Southeastern Kenya remains a frontier hydrocarbon province. This study employed a play-based exploration approach to delineate petroleum plays in the offshore Lamu Basin using integrated interpretation of gravity data, 2D seismic data, and selected well information. Traps/prospects and plays were interpreted using seismic facies analysis, reflector terminations, seismic attributes and sequence stratigraphic (system tract) relationships. Due to the limitation of 2D seismic data, seismic attributebased delineation of stratigraphic traps was not extensively applied. The study aimed at delineating petroleum plays of offshore Lamu Basin by identifying the structural and stratigraphic traps in the area and grouping them into petroleum plays. Regional gravity analysis reveals a structurally complex basin architecture characterized by deep depocenters and basement highs that strongly influence sediment distribution and hydrocarbon migration pathways. Based on shared source rocks, common tectonic settings, and similar trap types, twelve (12) distinct petroleum plays were delineated. The structural plays include Upper Cretaceous anticlinal play, Oligocene anticlinal play, Miocene faulted anticlinal play, Oligocene faulted anticlinal play, Upper Cretaceous rollover anticline play, Oligocene flower structure play, Oligocene-Miocene positive flower structure play, a multi-interval volcanic edifice play intruding from the Upper Cretaceous through the Oligocene-Miocene succession, and a Miocene tilted fault blocks play. The stratigraphic plays of the offshore Lamu Basin comprise Upper Cretaceous and Paleocene pinch-out plays, dominated by pinch-out traps, as well as a Miocene channel play characterized by channelized reservoir traps. Hydrocarbon charge for the delineated plays is inferred to originate primarily from Upper Cretaceous (Campanian) and Eocene marine source rocks, with migration facilitated by faultcontrolled pathways and carrier beds. Structural plays are the most prominent and well-defined on the available data, while stratigraphic plays provide additional exploration potential but with higher uncertainty. The results demonstrate that the offshore Lamu Basin hosts a diverse portfolio of viable petroleum plays, controlled by the interaction of tectonic evolution and stratigraphic architecture. This study has provided a coherent geological framework to guide future exploration efforts and highlights the need for basin modelling to further reduce exploration risk and refine prospect evaluation.
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    A mathematical model for COVID-19 transmission dynamics in a population with treated and untreated type 2 diabetes
    (Makerere University, 2026) Ampiire, Sheena
    The COVID-19 disease posed critical challenges to global health, particularly among individuals with pre-existing conditions such as Type 2 diabetes. While evidence suggested that Type 2 diabetes worsened COVID-19 outcomes, the e ect of Type 2 diabetes treatment on the disease dynamics remained unclear. This study formulates and analyzes a deterministic SEIR mathematical model of COVID-19 transmission in a population with and without Type 2 diabetes, subdividing diabetics into untreated and treated groups. The study derives the basic reproduction number (R), assesses equilibrium stability, and conducts sensitivity analysis to identify key parameters that in uence infection dynamics. Numerical simulations indicate that treatment of Type 2 diabetes reduces the infectious diabetic population, increases recovery, and lowers the basic reproduction number under appropriate parameter values.
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    Hydrogeological characterization of the groundwater resources in Lwengo District, Central Uganda.
    (Makerere University, 2026) Nakiyimba, Milly.
    This study presents a hydrogeological characterization of groundwater resources in Lwengo District, Central Uganda, focusing on aquifer properties, groundwater flow dynamics, hydrochemical composition and the factors influencing groundwater recharge using secondary datasets from the Directorate of Water Resources Management (DWRM/MWE), including borehole logs, aquifer test reports, topographical information and hydrochemical datasets. Aquifer parameters were estimated from four long-duration pumping tests using the Theis (1935) and Cooper-Jacob (1946) methods, while hydrochemical analyses were used to classify groundwater types and identify controlling geochemical processes. Results indicate that groundwater occurs mainly within weathered and fractured crystalline basement rocks under confined to semi-confined conditions. Water bearing zones occur at depths of 22–50 m below ground level, with static water levels ranging from 8–20 m. Aquifer parameters indicate low to moderate productivity, with transmissivity values of 0.3–5.5 m²/day, hydraulic conductivity of 0.02–0.2 m/day and storativity ranging from 2 × 10⁻⁵ to 1 × 10⁻⁴. Groundwater recharge is influenced by rainfall, topography, land use and the weathered and fractured basement geology, resulting in spatial variability across the district. Groundwater is predominantly characterized by Ca-Mg-HCO₃ and Ca-Mg-SO₄-Cl facies, controlled mainly by rock–water interaction and silicate weathering. Moderate mineralization was observed, while elevated nitrate and phosphate concentrations in some boreholes suggest localized agricultural and sanitation impacts. The findings demonstrate that groundwater occurrence in Lwengo District is structurally controlled and spatially heterogeneous, highlighting the importance of integrating geological, structural, geophysical, recharge and water quality assessments for sustainable groundwater resource development and management.