School of Physical Sciences (Phys-Sciences)

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    A 3d basin modelling approach to the assessment of hydrocarbon potential of Lake Edward basin, western Uganda
    (Makerere University., 2023-09-06) Atwebembeire, Conscent
    Lake Edward basin is a rift basin located in the extreme south of the Ugandan portion of the western arm of the East African Rift System (EARS), popularly known as the Albertine Graben. 3D basin modelling approach was applied to Lake Edward basin with the objective of gaining an understanding of its hydrocarbon potential. The approach utilized 2D Seismic data, well data, geochemical data and well completion reports from Lake Edward basin. 2D seismic data were integrated with well log data to define stratigraphic framework of the basin, onto which heat flow and geochemical characterization was undertaken to establish the possible potential source rocks of the basin. The integrated 3D basin modelling revealed the burial history, including the development of potential entrapment and source rock maturation. The major structures responsible for the hydrocarbon migration and entrapment in the field as interpreted are fault structures especially tilted faults blocks and normal faults. PetroMod software (version 2018.2) produced hydrocarbon maturation and generation model of the Lake Edward basin. The model shows that the source rock, Lower Ngaji Formation is currently at temperatures between 50oC-80oC. According to the model, the source rock, Lower Ngaji with typical characteristics of a mixture of Type II and III kerogen is immature with respect to petroleum generation. The research has provided a better understanding of key controls on hydrocarbon potential of Lake Edward basin and has enhanced the understanding of the timing and extent of hydrocarbon generation in Lake Edward basin and so the petroleum exploration risk can be potentially reduced This is useful for the oil and gas industry in the country as the findings are helpful in setting the next drilling phase of future exploration activities.
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    Abundance and some aspects of breeding biology of African Catfish (Clariasgariepinus) in Kafu Riverine wetland
    (Kikonyogo, F.E. (2017). Abundance and some aspects of breeding biology of African Catfish (Clariasgariepinus) in Kafu Riverine wetland. Unpublished masters dissertation. Makerere University, Kampala, Uganda., 2017) Kikonyogo, Francis Exavier
    Various studies on the ecology and biology of Clarias gariepinus have been carried out elsewhere by different scholars but not specific to Kafu Riverine wetland, because of its intraspecific ecological variations, fisheries resource management decisions that have been taken have not helped to address the environmental and human induced problems in the river catchment areas, therefore information generated from this study will help to address the above problems. This riverine wetland has two habitat types (open pools of water and closed wetland) this support a variety of fish species including Clarias gariepinus which account for 82% of the fishery of river Kafu. In this study, fish samples were caught using various fishing gears such as basket traps gillnets and hooks. This was done once every fortnight and average catch per unit effort derived. The relations of fecundity to standard length (cm), total weight (g) and gonadal weight (g) were determined by regressionPearson‟s statistics.Results of this study revealed that, the abundance of Clarias gariepinusper day was significantly higher in the open than in the closed wetland type, the abundance was6.19±0.65and 3.0±0.65 fish in the open and closed wetlands respectively (P< 0.008). Within seasons, a significant difference in abundance of this species per day was 6.75±0.612and 2.43±0.612in the wet and dry seasons, respectively(P<0.042).Clarias gariepinus exhibited a weak positive linear relationship with total length and somatic weight. However, a strong positive linear relationship was found between fecundity and gonadal weight: y = 366.3x + 7982, (r2=0.721, N = 157, p< 0.01). Therefore, gonadal weight was the best indicator of fecundity accounting for 72% of the variation in fecundity of Clarias gariepinus in Kafu riverine wetland. Gonadal somatic index (GSI) values of both females and males were at their highest during the months of October and November respectively and eventually started declining in mid-November which indicated the spawning activity. Therefore, November was presumed to represent the spawning period of Clarias gariepinus in Kafu riverine wetland. Males matured earlier (L50=33.7cm) than females (50= 33.7cm). Despite of C.gariepinus enormous contribution to the livelihood of the people especially in its catchment area, it is being threatened by human activities such as over fishing and environmental fluctuations which have caused changes in the abundance and reproduction of this specie Therefore information from this study will help to update managers especially in the affected districts on the key aspects of ecology and reproduction that needs attention for sustainable management of the fisheries resources.
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    Adsorption behavior of acid-leached clays in bleaching of oil
    (Scientific Research Publishing, 2015) Mukasa-Tebandeke, I. Z. ; Ssebuwufu, P. J. M. ; Nyanzi, S. A. ; Nyakairu, G. W. ; Ntale, M. ; Lugolobi, F. ; Schumann, Andreas
    The available data have shown that acid-leached clays had sites for adsorption of impurities in oils. Data obtained on residual impurities in cotton and sunflower-seed oils bleached with the same clay materials produced linear Langmuir and Freundlich isotherms. The increase in constant, k with increase in both temperature of thermal activation and concentration of acid used to leach the clay, suggests that bleaching efficiency increased. The value of n decreased with increase in temperature of activation and concentration of acid used to leach the clay suggesting that bleaching capacity increased. The mineral compositions of the clays influenced their surface, structural and bleaching properties.
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    Advances in carbon dioxide and propylene oxide copolymerization to form poly(propylene carbonate) over heterogeneous catalysts
    (Elsevier, 2022) Mbabazi, Ruth ; Wendt, Ola F. ; Nyanzi, Steven Allan ; Naziriwo, Betty ; Tebandeke, Emmanuel
    Chemical conversion of carbon dioxide (CO2) into value-added products is an attractive industrial process because it offers several economic and environmental advantages. This review presents advances and challenges in the CO2 and propylene oxide (PO) co-polymerization using heterogeneous catalysts to form poly (propylene carbonate) (PPC), an environmentally friendly polymer with several applications. In the co-polymerization process, CO2 is employed as a green carbon source, an alternative to the toxic phosgene which has numerous negative environmental impacts. However, this route of polycarbonate production, is hindered by the chemical inertness of CO2, and to overcome this, various catalysts have been developed. A number of heterogeneous catalysts including carboxylates, double metal cyanides and composites, have achieved varying success in activating CO2 in the production of polycarbonates. The effect of different reaction conditions including pressure, temperature and solvent has been explored. The limitations faced by various heterogeneous catalysts and im- provements made over the past decades have been highlighted. Mechanistic insights for the production of PPC from CO2 and PO have been presented and the differences in both the regioselectivity and stereochemistry of the resultant polymers discussed.
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    Analysis of x-ray characteristics of narrow line Seyfert 1 Galaxies from nuclear spectroscopic telescope array data
    (Makerere University, 2022) Kamulali, Juma
    Narrow line Seyfert 1 (NLS1) galaxies are among the most variable active galactic nuclei (AGN) in the sky. Hard X-ray spectral and timing analysis of two of these galaxies, NGC 4051 and ARK 564, using NuSTAR data is presented. The data was processed using nupipeline task in HEASoft and spectral, light curve and response files were generated using nuproducts module. X-ray spectra of the two sources were fitted in XSPEC with a reflection model (Pexrav) plus a Gaussian component (Gauss), corrected for line-of-sight galactic absorption using photo-electric absorption component (Phabs). The intrinsic powerlaw continuum is of slope Γ > 1.59, which is slightly steeper than the typical Seyfert 1 galaxies. Strong emission lines (EW > 100 eV) were detected at ∼ 6.4 keV in the two X-ray sources. The X-ray spectra of these sources above 10 keV exhibit a Compton hump, produced by Compton backscattering of hard X-ray photons by reprocessing optically- thick accretion disc, and is prominent at high energies. The deduced 3-79 keV luminosity of the two studied X-ray sources differ by 2 orders of magnitude (∼ 6.12×1041 ergs-1 for NGC 4051 and ∼ 2.47×1043 erg s-1 for ARK 564), thus ARK 564 is brighter than NGC 4051 in hard X-ray energies. High-amplitude X-ray variability of NLS1 galaxies was analysed by means of cross power spectral density (CPSD) in this study since multiple instrument simultaneous observations were made by NuSTAR. The average CPSD for each of the two sources was generated using High Energy Data Reduction Interface from Command Shell and the fitting performed in XSPEC. The spectra were fitted quite well in the frequency range ∼ 10-3 to ∼ 0.2 Hz, using four broad Lorentzian models with ARK 564 revealing more variability power estimates (total rms = 63.59%) than NGC 4051 (total rms = 37.3%). The coherence of variablity (Q < 2) of the X-ray sources shows no evidence of quasi-periodic oscillations (QPOs) possibly owing to the short period NuSTAR observations. Only two NLS1 galaxies have been considered. Further analysis of a large sample of these objects and the typical Seyfert 1 galaxies needs to be done in order to draw meaningful deductions about evolution of their hard X-ray spectra and timing properties and to distinguish between the two classes.
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    Anti-bacterial activity and characterisation of compounds of leaf extracts of Erlangea tomentosa S. Moore
    (Makerere University, 2022-12-05) Ekyibetenga, Yeremiah
    Bacterial infections such as pneumonia, lower respiratory tract infections, gastrointestinal disorders and skin infections are health burden to mankind. In Uganda, several medicinal plants are locally used to treat various bacterial infections because of affordability and accessibility of herbal medicine. Erlangea tomentosa (ET) is one of the plants used to treat various bacterial infections such as gastrointestinal disorders, skin infections, diarrhea, syphilis and cough. However, compounds responsible for its activity are not known and this limits its wider use and development into drugs. Therefore, the purpose of the study was to characterise the compounds from leaf extract of ET that could be responsible for its antibacterial properties. The leaves were collected, ground into a course powder and extracted sequentially using n-hexane, dichloromethane, ethyl acetate and methanol. Antibacterial activity of the extracts against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Klebsiella pneumoniae (K. pneumoniae) and Salmonella typhi (S. typhi) was done to identify the more active extract. Isolation of compounds from ethyl acetate extract (ETE) and dichloromethane extract (ETD) was done by column chromatography and compounds characterised by spectroscopic techniques. ETE showed a highest zone of inhibition (17.3 ±0.6, 16±1.0, 11.7±0.6 and 13.7±0.6 mm) followed by methanol extract (ETM) (10.3±0.6, 15±1.0, 14.7±0.6 and 10±0.0 mm) for E. coli, S. aureus, K. pneumoniae and S. typhi, respectively and ETD (17.3±0.6 and 10±0.0 mm) for E. coli and S. typhi, respectively. Hexane extract showed no zone of inhibition. Eriodictyol-7-O-β-glucoside (1) and 5, 7, 3’, 4’-tetrahydroxy-7-O-[6"-O-(acetyl)-β-D-glucopyranosyloxy]-flavanone (2) were isolated from ETE while di-(2-ethylhexyl) phthalate (3) was isolated from ETD. This was the first time to identify these compounds from the plant species of genus Erlangea. Compound 3 has been reported to have a moderate activity against Bacillus subtilis, Staphylococcus aureus, Streptococcus equosemens, Escherichia coli and Pseudomonas aeruginosa. Therefore, the bioactivity of the leaf extracts and the presence of compound 3 that is reported to be very active against various bacterial strains support the use of the plant. Compounds from ETM should be isolated and characterised to obtain more bioactive compounds from ET.
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    Anti-bacterial activity and characterization of compounds from the leaf extract of Solenostemon Latifolius Hochst.ex benth.
    (Makerere University, 2021-03) Imalingat, Betty
    Infectious diseases have continuously been reported among the leading causes of death in the world. These include bacterial infections like tuberculosis and pneumonia. Several antibiotics have been used against these infections. However, bacteria are becoming resistant to a number of antibiotics, leading to increased mortality, morbidity and treatment costs. Therefore, there is need to discover more effective antibacterial drugs and plants have been sought as sources of antibiotics. The aim of this study was to isolate and identify antibacterial compounds from Solenostemon latifolius, a plant that is locally used to treat bacterial infections in Uganda. The plant sample was collected, dried and ground into a fine powder. The powder was extracted using distilled water and 1:1 DCM -methanol mixture. Phytochemical screening was done and both extracts and isolated compounds were subjected to antibacterial test using the agar well diffusion method. The organic extract was then partitioned and subjected to isolation using a column packed with silica gel. Structural elucidation of the isolated compounds was done using NMR, MS and UV spectroscopy. Phytochemical screening revealed presence of flavonoids, terpenoids and steroids among others. The zone of inhibition (ZOI) for the organic extract was 14 mm and 18 mm against Staphylococcus aureus and Escherichia coli. The aqueous extract had ZOI as 13 mm for E. coli. S. aureus was not susceptible to the aqueous extract. Isolated compounds were identified as Coleone U, β-sitosterol, stigmasterol and 3,4-dihydroxyphenyl caffeate. Coleone U (ZOI between 10-12 mm at a concentration of 40 mg/ml) had activity comparable to that of gentamicin standard used. Therefore, Solenostemon latifolius is a medicinal plant with several classes of phytochemicals responsible for its antibacterial activity. This supports its use as a medicinal plant against bacterial infections
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    Anti-plasmodial activity and phytochemical analysis of leaf extract of Chenopodium Opulifolium Schrad. EX W.D.J. Koch and Ziz used in Uganda
    (Makerere University, 2022-04-28) Juma, Saidi,
    Malaria is a life-threatening disease caused by Plasmodium species. It had one of the highest motality and morbidity rates globally. with 229 million cases and 409,000 malaria death in 2019. In Uganda. Malaria has an incidence rate of 26% and it kills 34 people per day. Malaria control has been more effective with antimalarial drugs commonly developed from natural products but are toxic and plasmodium species has evolved, developed resistance where control will greatly require new alternative effective, tolerable, and affordable antimalarial medicines. In this study, Chenopodium opulifolium was investigated for its antiplasmodial activity, phytochemical and antiplasmodial compounds present in its leaves. The plant was selected based on its widespread use in traditional herbal medicine. The plant leaves were collected from Mbirizi, Masaka District, Uganda in June 2019. Extraction was done seqentially with n-hexane, DCM, EtOAc, MeOH and water by means of maceration. The antiplasmodial activity of each extract and compound was tested against P. falciparum 3D7 strain and clinical field isolates KOM_234 and KDH_204 using a fluorescence based SYBR Green 1 assay technique. Separation and purification of the compounds in the most active methanol and DCM extracts was done using column and thin layer chromatography. The compounds were identified by one dimensional and two dimensional (1D and 2D) 1H and 13C NMR, FTIR, Mpt and GC-MS techniques. The antiplasmodial activity test against P. falciparum 3D7 strain, it showed that DCM extract obtained the highest activity with IC50 value of 0.1177 µg/mL followed by methanol extract (1.189 µg/mL), hexane extract (4.850 µg/mL), EtOAc extract (4.856 µg/mL) and aqueous extract (10.24 µg/mL). Methanol extract also demonstrated a promising antiplasmodial activity against P. falciparum clinical field isolate KOM_234 and KDH_204 with IC50 of 5.30 µg/mL ±1.10 and 5.06 µg/mL ±2.23 respectively. Isolation and purification resulted in the identification of two known compounds which are allantoin and decan-2-one. In addition, 19 compounds were identified in the volatile components of the plant using GC-MS analysis which were reported to have numerous bioactivities. Allantoin demonstrated a high antiplasmodial activity against the clinical field isolate KOM_234 with IC50 of 2.29 µg/mL ± 0.98 and a promising activity against clinical field isolate (KDH_204) with IC50 of 10.94 µg/mL ± 1.51. The findings show that the crude extracts, isolated pure and characterised compounds of C. opulifolium leaves have got antiplasmodial activity. This justifies the use of this plant in traditional medicine and indicates a promising potential for the development of medicinal agents.
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    Antiplasmodial activity, Toxicity and Phytochemistry of Selected Plant Species used by Rukararwe and Prometra Herbalists in Treatment of Malaria in Uganda
    (Makerere University, 2021-03-30) Adia, Madina Mohamed
    Resistance of malaria parasites to known antimalarial drugs necessitated to finding new drugs from natural products which are readily available to treat malaria. The study documented; medicinal plants used in malaria treatment by Traditional Herbalists of Prometra and Rukararwe, determined antiplasmodial activity and toxicity, and characterised isolated chemical structures of the compounds. The selected plant species were identified from ethnobotanical surveys. Micro Mark III test was used for in vitro antiplasmodial analysis of the extracts and some pure compounds. Acute and sub-chronic toxicity was done on Wister mice and Albino rats. A combination of chromatographic techniques were used to isolate pure compounds and their chemical structures were determined using spectroscopic techniques. 86 and 54 plant species were used in malaria treatment by Prometra and Rukararwe Herbalists respectively. Clerodendrum rotundifolium (leaves) and Zanthoxylum chalybeum (stem bark) were selected for further investigation. The most active extracts against Plasmodium falciparum from Z. chalybeum and C. rotundifolium had IC50 values of ≤ 0.03 µg/mL and the water extracts had very low toxicity values (LD50 20,216 mg/kg and 8,300mg/kg) respectively. A dose of 200 mg/kg of the water extract of C. rotundifolium was found to be safe for use. Fagaramide from Z. chalybeum, Verbascoside and Quercetin from C. rotundifolium were isolated and elucidated with IC50 values of 2.85 µg/ml, IC50 17.0 µg/ml and IC50 27.0 µg/ml respectively against P. falciparum. The findings indicate that the selected plants are efficacious and non-toxic which justifies their use in malaria treatment. The isolated compounds are potential antiplasmodial agents for the discovery of new natural antimalarial compounds. The compounds can also be used as markers in the formulation of antimalarial herbal remedies from these plants.
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    Assessing Enrofloxacin use practices and residue levels of Enrofloxacin/Ciprofloxacin in breast and liver tissues of broiler chicken sold in selected markets in Kampala Capital City-Uganda
    (Makerere University, 2022) Munanura, Edson Ireeta
    Human exposure to veterinary drugs like fluoroquinolones occurs due to the presence of their residues in foods from animal sources in varying concentrations. The existence of antibiotics residues in foodstuff can pose great public health problems to consumers. To limit the risks from such exposure, Maximum Residue Levels (MRLs) for specific drugs have been set by various continental regulatory bodies. Withdrawal time (WDT) allows tissue concentrations of the drugs to reduce to levels below the drug’s MRL but these are largely not adhered to by farmers. The purpose of this study was to assess enrofloxacin use patterns and assess residue levels of enrofloxacin/ciprofloxacin in breast muscle and liver tissues of broiler chickens sold for consumption in Kampala capital city. A total of 68 chicken breast tissues and liver tissues samples were collected from main markets over one month. Analysis was performed using HPLC coupled with a UV detector. For the enrofloxacin use patterns sub-study, 34 broiler farmers and 10 veterinary drug vendors were interviewed using a questionnaire. From the field survey, the most used antibiotics for the management of poultry diseases were enrofloxacin (100%), oxytetracycline (80%), and amprolium (30%). Enrofloxacin was prescribed majorly for the management of respiratory diseases (100%), and salmonella infections (40%), but also for disease prevention (60%). On average every week, over 15 farmers procured or got prescriptions of enrofloxacin to treat their chicken. The most used brands of enrofloxacin were Enrosol-s® (61.8%), Enrovet® (17.6%), and Enroveto-20® (14.7%). Most of the farmers interviewed had completed secondary and tertiary levels of education (76.5%). The veterinary drugs vendors included; one veterinary extension officer, 5 veterinary assistants, and 4 veterinary surgeons. Enrofloxacin/ciprofloxacin residues were identified in 35.3% (12/34) of the muscle and 38.2% (13/34) of the liver tissues analyzed. Furthermore, of those samples of muscle and liver that tested positive for enrofloxacin/ciprofloxacin, 25% (3/12) and 38.5% (5/13) respectively had drug concentrations higher than the recommended MRLs. The overall mean concentration of enrofloxacin/ciprofloxacin in the broiler chicken muscle and liver tissues was found to be 83.6 (±34.5) µg/kg and 171.5 (±75.9) µg/kg. More so, although over 76% of the farmers knew the WDT for enrofloxacin, none of them adhered to this. This could be attributed to the fact that the veterinary drug vendors do not always emphasize the importance of WDT. In this study, over 70% of the farmers reported that the veterinary drug vendors were not giving them WDT information.
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    Assessment of Geological Controls on Reservoir Heterogeneity in Kingfisher Oilfield Lake Albert Basin, Western Uganda
    (Makerere University, 2023-08-14) Kobusingye, Judith
    The Kingfisher oilfield is one of the key discovery fields found in the Albertine Graben located in the Lake Albert basin. The Kingfisher reservoir zones are characterized by variations in facies distribution, pressure regimes and fault uncertainty thus implying reservoir heterogeneity. An integrated approach, using seismic attributes and well data was adopted to assess the geological controls on reservoir heterogeneity in the Lake Albert basin. Faults were interpreted with the help of seismic attributes. Gamma-ray log signatures at different locations and three seismic attributes were used to determine reservoir architecture and geometry. Genetic inversion was used to estimate porosity distribution within the reservoir zones. Two fault trends, one oriented in NW-SE, and another set of faults oriented in NE-SW were observed. The interaction of these sets of faults resulted in the compartmentalization of the reservoir due to the alternating sand-shale lithology and high seismic activity in the area. Prominent channels trending in the northeast direction were dominant facies in the reservoir zones. The porosity of the study area ranges from 10%-30% with the sites of highest porosity (30%) observed to be along channels and some faulted zones in the north end. Porosity variation within the study mainly arose from the difference in sedimentary facies. The results confirm that faulting and facies distribution which link to the depositional environment are the two fundamental elements that defined the reservoir heterogeneity in Kingfisher reservoirs.
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    Assessment of mercury bioavailability in soils and potential uptake by food crops grown around selected artisanal and small-scale gold mining areas of Eastern Uganda
    (Makerere University, 2024) Kayeera, Derrick
    The unregulated use of elemental mercury (Hg) in artisanal and small-scale gold mining (ASGM) to extract gold from its ore results in metal pollution of various environmental systems. ASGM employs the mercury amalgamation method to obtain gold using locally-made technologies and tools such as hoes, pickaxes, and basins. The amalgamation method results into the emission of elemental mercury as vapor into the atmosphere and the discharge of wastewater as tailings, which drain along streams with a good percentage adsorbing onto the soils and sediments before final deposition in low altitude areas such as swamps, lakes, and rivers. Vaporized mercury is deposited on the vegetation and soil, which prompts vegetation absorption through the stomata during respiration. Direct uptake through the roots is the main absorption route of soil mercury to plants. Soils and plants are therefore of concern because man, who is at the top of the food chain, is exposed to elevated levels of mercury. This study aimed to assess mercury bioavailability in soils and its potential uptake by food crops grown around selected ASGM areas in Namayingo and Busia of Eastern Uganda. The acid digestion method was used for extraction and spectrometry used for analysis of mercury in soils and plants. All the soils from the three sites of Agata, Nakudi and Bukana were slightly acidic with mean pH values of 6.6, 6.9 and 6.5 and electric conductivity values were 176.3, 169.0 and 143.1 s/m, respectively. Agata site had least total organic matter content of 2.0%, Nakudi site with 2.1% whereas Bukana site had the highest total organic matter content of 3.5%. Total mercury concentrations of soils in the study sites was in the order; Agata > Nakudi > Bukana with mean values of 88.1, 51.2 and 44.0 mg/kg, respectively. It was observed that 2.3% of total mercury in soils was bioavailable for plant uptake, with 0.7% of total mercury in the methyl mercury form which is very mobile and toxic to plant and animal life. Hg was more bioavailable in the Agata ASGM site with a mean total mercury concentration in the mobile phase at 2.1 mg/kg followed by the Nakudi ASGM site with 1.1 mg/kg of total mercury whereas the Bukana site was observed with the least bioavailable mercury with a mean total mercury concentration in the mobile phase as 0.9 mg/kg. Total mercury concentrations in food crops were observed highest in leafy crops, moderate in tubers, and least in grains, with 87% of the studied food crops having total mercury concentrations above the acceptable maximum limit of 0.05mg/kg (FAO/WHO). Health risk assessment from consumption of studied crops using the Health Risk Index (HRI) was observed above the acceptable limit of 1 in 57% of the total food crops, which indicated high toxicity upon ingestion.
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    Assessment of organochlorine pesticide residues in blood and placenta tissues of mothers living in Kanungu District and Kampala Capital City
    (Makerere University, 2019-12) Omoding, Daniel
    This study determined the levels of organochlorine pesticides in blood and placenta tissues of mothers from Kanungu District (N=26) and Kampala Capital City (KCC) (N=26). Samples for Kanungu District were collected from Kambuga hospital while those for KCC were collected from Nsambya hospital. Extraction and clean- up was done using solid phase and florisil method, respectively. Analysis of extracts was done using the GC-ECD and GC-MS for confirmation. Samples were considered positive when their residue levels were greater than or equal to the limits of detection (LOD). The LOD (ng g-1) were: p,p′-DDT (0.06), p,p′-DDE (0.3), o,p′-DDE (0.05), p,p′-DDD (0.07), o,p′-DDD (0.09), aldrin (0.1), dieldrin (0.06), lindane (0.2), α-endosulfan (0.2) and β-endosulfan (0.05). The mean recoveries of the detected residues varied from 67.0 to 80.0 % and 75.0 to 88.0% in blood samples at spiking levels of 0.4 and 1.0 ng g-1, respectively, where as for placenta tissues it ranged from 69.0 to 78.3% at 0.4 ng g-1 and 77.3 to 87.0% at 1.0 ng g-1. Since most recoveries were above 60%, residue levels have not been corrected for recovery. The ΣOCPs was 425.46 and 65.28 ng g−1 l.w in blood samples from Kanungu District and KCC, respectively. The high levels of OCPs for Kanungu District could be attributed to their past use for agricultural and public health activities. o,p′-DDE was the most predominant metabolite of DDT in all the blood samples (contributed 36% to the ΣDDTs in Kanungu District and 40% in KCC). Levels of dieldrin and α-endosulfan were in the range n.d-5.10 ng g−1 l.w and 39.67-88.44 ng g−1 l.w, respectively in blood samples from Kanungu District where as those for Kampala Capital City were 1.73-4.25 ng g−1 l.w and n.d-11.30 ng g−1 l.w for dieldrin and α-endosulfan, respectively. Aldrin, lindane and β-endosulfan were not detected in all the blood samples analyzed. The presence of α-endosulfan and the absence of β-endosulfan in this study indicate recent input or lack of significant degradation of technical endosulfan. However, detection of epoxide analogue dieldrin and the absence of aldrin in the blood samples suggests past input of aldrin. In placenta tissues, DDTs were detected up to levels of 133.86 and 33.67ng g−1 l.w for Kanungu District and KCC, respectively. The ratio p,p′-DDE/p,p′-DDT for placenta tissues from Kanungu District was greater than 1, suggesting past input of technical DDT. Aldrin was detected in 69% of the samples from Kanungu District at a mean level of 4.50 ng g−1 l.w higher compared to dieldrin (4.29 ng g−1 l.w), indicating recent input of aldrin in the environment. The study also detected β-endosulfan however, no traces of α-endosulfan were detected in all the placenta tissues. This could be attributed to past input of technical endosulfan moreover endosulfan was banned for use in 2012. The demographic characteristics showed a positive and negative correlation of levels of OCPs with the age of mothers and increase in the number of births, respectively. It was concluded that higher levels of OCPs were in blood and placenta tissues of mothers who majorly consumed food of animal origin.
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    Assessment of organochlorine pesticide residues in cows’ fresh and pasteurized milk sold from Kampala markets, Uganda
    (Makerere University, 2010-05) Kampire, Edwige
    Concentrations of organochlorine pesticides (Lindane, Aldrin, Dieldrin, Endosulfan, p, p’- DDT, o, p’-DDT and p, p’-DDE) residues in cows’ fresh and pasteurized milk samples from Uganda were determined using a gas chromatograph with an electron capture detector and confirmed with a gas chromatograph equipped with a mass spectrometer [GC-MS]. 54 fresh milk samples and 47 pasteurized milk samples were analyzed for organochlorine pesticides. Five organochlorine pesticides were detected in the milk samples; namely Aldrin, Dieldrin, Endosulfan, DDT and its metabolites and Lindane. The average concentration of lindane was 26 ± 1.7 μg/kg in fresh milk samples (n=54) and 22 ± 1.5 μg/kg in pasteurized milk (n=47). Endosulfan concentration was 4 ± 0.3 μg/kg in the fresh milk samples and 3 ±1.0 μg/kg in the pasteurized milk samples. p,p’-DDE contained mean concentrations of 9.5 ± 2.0 μg/kg in fresh milk and 8 ±1.0 μg/kg in the pasteurized milk samples. p, p’-DDT recorded an average concentration of 33 ± 6.9 μg/kg in fresh milk samples and 25 ±5.0 μg/kg in pasteurized milk samples. The average concentration of o, p’-DDT in fresh milk was 9 ± 2.0 μg/kg and in pasteurized milk it was 7 ± 4.0 μg/kg. The mean concentration of aldrin was 9 ± 0.7 μg/kg kg in fresh milk samples and 6 ±1.0 μg/kg in pasteurized milk samples. Dieldrin was 7 ± 4μg/kg in the fresh milk samples and 5 ± 5 μg/kg in the pasteurized milk. The concentration of sum-DDT was 52 μg/kg and was found to range from 3 μg/kg to 33 μg/kg in the fresh milk and was 41 μg/kg in pasteurized milk with the range of 7 μg/kg to 25 μg/kg. Although, most of the organochlorine residues detected were below the maximum limits set by the FAO/WHO, bioaccumulation of these residues is likely to pose health problems in higher organisms like human beings.
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    Assessment of organochlorine pesticides in serum and urine of children from a community affected with nodding syndrome in Kitgum District
    (Makerere University, 2023-11-23) Odongo, Silver
    This study aimed at determining the concentrations of OCP residues in serum and urine of children from a community affected with nodding syndrome (NS) in Kitgum District, Northern Uganda. A total of 150 urine and 75 serum samples were collected from children aged 5 to 18 years from Tumangu village, Kitgum District, Northern Uganda. The samples were extracted using solid-phase extraction. The extracts were analysed for organochlorine pesticides (OCPs) using GC-MS/MS. The levels of ∑OCPs in all serum samples ranged from 12.78 to 30.56 ng/mL (mean 21.78 ±3.65 ng/mL). The levels of ∑OCPs in serum samples from nodding syndrome (NS) cases varied from 17.16 to 30.56 ng/mL (median 23.46 ng/mL). The concentrations in household controls (HC) and community controls (CC) were 14.44 to 29.72 ng/mL (median 20.35 ng/mL) and 12.78 to 27.19 ng/mL (median 20.71 ng/mL), respectively. Levels of ∑OCPs in all urine samples ranged from 0.26 to 7.69 ng/mL (mean 2.28 ± 1.21 ng/mL). Levels of ∑OCPs in urine samples from NS, HC, and CC varied from 0.26 to 6.15 ng/mL, 0.26 to 7.69 ng/mL, and 0.26 to 4.48 ng/mL, respectively. Correlation and linear regression analysis showed that potential markers for ∑HCHs, ∑CHLs, ∑endosulfan, and ∑DDTs accumulation in children were gamma-HCH, heptachlor-exo-epoxide, endosulfan-α and p,pʹ-DDD for NS, while those for the HC and CC were alpha-HCH, heptachlor, endosulfan-α and p,pʹ-DDE, respectively. However, more studies with larger datasets may be needed to confirm the observed trend. Furthermore, study results showed that there is no conclusive evidence to link NS onset in children to OCPs exposure.
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    Assessment of polycyclic aromatic hydrocarbons in the breast milk of mothers from Kampala capital city, Uganda
    (Makerere University, 2022) Ssepuya, Fred
    The aim of this study was to investigate levels of polycyclic aromatic hydrocarbons (PAHs) in breast milk samples from healthy mothers who have lived in Kampala capital city (urban and industrialized area) for more thancarcin five years. In this study, the rural areas of Nakaseke District were used as a control site for comparison purposes. A total of sixty samples (30 from Kampala and 30 from Nakaseke) were collected between February and October 2019. The samples were extracted using liquid-liquid extraction and clean-up was performed on silica column. Analysis of the samples was done using Gas chromatography triple quadrupole (GC-MS/MS). Total concentration of thirteen PAHs (∑13PAHs) in the samples was 283.74 and 29.63 ng g-1 lipid weight in Kampala and Nakaseke, respectively. The levels of PAHs in Kampala were significantly higher than those from Nakaseke (p<0.05, Mann-Whitney U test). Low molecular weight PAHs (LPAHs) were more predominant than high molecular weight PAHs (HPAHs). Naphthalene was the most abundant and frequently detected PAH (90.0%) followed by acenaphthene (81.7%), fluorene (81.7%) and fluoranthene (81.7%). In the present study, risk assessment for carcinogenicity and mutagenicity on contaminated breast milk was 7.7×10−4 and 6.3×10−4, respectively. This means that approximately 8 and 6 out of 10,000 infants breast fed in Kampala may have cancer and non-cancer related adverse diseases, respectively during their life time as a result of taking breast milk contaminated with PAHs, thus suggesting a negligible risk. Therefore, the breast milk of mothers from Kampala is safe for the infant.
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    Assessment of radioactivity levels and radiological risks of chemical fertilizers in Kampala City, Uganda
    (Makerere University, 2025-04-04) Atine, Joseph
    The agricultural sector relies heavily on fertilizers to boost crop productivity, driving global growth in the fertilizer industry. Phosphate fertilizers, used worldwide at a rate exceeding 30 million tons annually, enhance yields, and restore soil. In Uganda, agricultural households using fertilizers apply an average of 46.9 kg/acre in the first season and 36.3 kg/acre in the second season, with urea and diammonium phosphate (DAP) dominating the market while NPK and calcium ammonium nitrate (CAN) are actively traded. Although essential for agricultural productivity and food security, chemical fertilizers may contain radioactive elements like thorium, uranium, and their decay products, which may accumulate in soil, crops, and the food chain, posing health risks. This study assessed radioactivity levels and radiological risks of chemical fertilizers available in Kampala, Uganda, focusing on their impact on farmers, workers, and the public. Samples were analyzed using gamma spectrometry (NaI detector, MAESTRO software). High activity levels of Ra-226, Th-232, and K-40 were found in some DAP and NPK fertilizers. The highest mean levels were 67.02 Bq/kg (Ra-226) and 28.18 Bq/kg (Th-232) in DAP, and 589.26 Bq/kg (K-40) in NPK, with Ra-226 and K-40 exceeding global limits. The absorbed dose remained below the global limit of 59 nGy/h for each fertilizer brand, but the outdoor annual effective dose (AED) in some cases exceeded the limit of 0.07 mSv/y and varied from 0.01 to 0.09 mSv/y. The mean radium equivalent activity was below 370 Bq/kg for all the fertilizer brands, with internal and external hazard indices under unity. A strong correlation was observed between radiological parameters, with some fertilizers showing slightly elevated radionuclide levels and radiological risks. DAP with high Ra-226 and NPK with elevated K-40 require careful handling to minimize radiation exposure for farm workers, employees, and the public. A high-resolution detector, such as a high-purity germanium detector, is recommended for detecting low-activity radionuclides from fertilizers and for a more precise spectral analysis.
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    Atmospheric concentration of selected trace gases over Uganda
    (Makerere University, 2019) KATENDE, SAMUEL
    The atmospheric concentration of the trace gases of CO2, CH4, NO2 and SO2 over Uganda was obtained at the stations of Makerere, Mukono, Lira, Tororo and Kasese. Data used in this study was retrieved from the Ozone Monitoring Instrument (OMI) sensor aboard the Aura Satellite, the Atmospheric Infrared Sounder (AIRS) aboard the Aqua satellite and the Ground based instruments (Combo Diffusion tubes). During the study analysis, monthly and annual averages were obtained from which for example CO2 for Makerere/Mukono, Lira, Tororo and Kasese had annual averages of about (388.9 ± 8.2), (388.7 ± 8.5), (388.9 ± 8.3) and (388.8 ± 8.2) ppmv yet the SO2 concentration for the stations ofMakerere, Mukono, Lira, Tororo and Kasese were (0.65 ± 0.07), (0.63 ± 0.08), (0.61 ± 0.06), (0.69 ± 0.27) and (0.60 ± 0.08) DU respectively. From the developed averages, the highest and lowest concentrations were obtained and accounted for after which the respective concentration maps were as well generated. Seasonally, it was observed that the selected trace gases vary according to the weather season of the year as well like CH4 concentration increased in the months of February and November which are known to be sunny months with relatively high temperatures. Although all the obtained concentrations were still generally below the limits in the published papers, measures must be put to check on the steadily improving concentration levels. The comparison between the ground-based measurements and the satellite overpass data gave comparable results with a relatively small percentage difference. For example, the institute of public health - Mulago had an average ground based measurement of about 1.76 μg/m3 yet the satellite overpass average was about 1.26 μg/m3 which resulted into a percentage discrepancy of about 28.4%
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    An Automatic Electronic Photovoltaic Heating System for Charging Thermal Energy Storage Tank
    ( 2023-01-03) Ochola, Francis
    Power generated by Photovoltaic modules can be directly used for heating. However, due to the intermittent nature of solar irradiance, such a PV heating system requires a controller which can automatically select the appropriate heating element which matches the maximum power point. In this study an electronic circuit was constructed using an arduino 2560 mega board, a current sensor, a voltage sensor, a SD card module and a real time clock that automatically selects a heating element according to the variation in solar irradiance. Both the current and voltage from the solar panels were measured and recorded in the SD card. The performance of the electric circuit was tested in heating 7 litres of thermal energy storage oil on different days. The experimental results showed that the thermal energy storage oil was heated to 208 degree Celsius in about 4 hours on a day of 5 sunshine hours and 160 degree Celsius in about 6 hours on a day of 3 sunshine hours. The heating efficiencies were 19% for oil TES system and 26% for water TES system.
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    Bio-oil production from water hyacinth by hydrothermal liquefaction process using iron oxide-based nanocomposites as catalysts
    (Makerere University, 2023-01-09) Aturagaba, Godwin
    The iron oxide nanocatalyst and iron oxide/nickel oxide nanocomposite were synthesized by the co-precipitation method and used in the hydrothermal liquefaction (HTL) of water hyacinth. The composition and structural morphology of the synthesized catalysts were determined using atomic absorption spectroscopy (AAS), energy dispersive X-ray fluorescence (EDXRF) spectrometry, and scanning electron microscopy (SEM). The particle size distribution of the catalyst nanoparticles was determined by the Image J software and plotted using the Originlab software. Three reaction parameters were optimized through the central composite design of response surface methodology (RSM). These reaction parameters were: temperature, residence time, and catalyst dosage. A maximum bio-oil yield of 58 wt. % and 59.4 wt. % was obtained using iron oxide nanocatalyst and iron oxide/nickel oxide nanocomposite, respectively compared to 50.7 wt. % obtained in absence of the catalyst. The maximum bio-oil yield was obtained at a temperature of 320 °C, 1.5 g of catalyst dosage, and 60 min of residence time. The composition of bio-oil was analyzed using gas chromatography-mass spectroscopy (GC-MS) and elemental analysis. The GC-MS showed an increase of hydrocarbons from 58.3 % for uncatalyzed hydrothermal liquefaction to 83.09 % and 88.66 % using iron oxide nanocatalyst and iron oxide/nickel oxide nanocomposites respectively. Elemental analysis revealed an increase in the hydrogen and carbon content and a reduction in the nitrogen, oxygen and sulphur content of the bio-oil when HTL was done in presence of catalyst nanoparticles compared to HTL in absence of catalyst nanoparticles. The high heating value increased from 33.5 MJ/Kg for uncatalyzed hydrothermal liquefaction to 35.5 MJ/Kg and 38.6 MJ/Kg using iron oxide nanocatalyst and iron oxide/nickel oxide nanocomposite, respectively. The catalyst nanoparticles were recovered from the solid residue by sonication and magnetic separation and recycled. The recycled catalyst nanoparticles were still efficient as hydrothermal liquefaction (HTL) catalysts and were recycled four times. The application of iron oxide-based nanocomposites in the HTL of water hyacinth increases the yield of bio-oil and improves its quality by reducing hetero atoms thus increasing its energy performance as fuel. Iron oxide-based nanocomposites used in this study are cheaper, widely available and can be easily recovered magnetically and recycled. This will potentially lead to an economical, environmentally friendly and sustainable way of producing bio-oil from biomass.