Masters Degree Dissertations

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12504/114

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A study of the coefficient of thermal diffusivity of building bricks made from clay and local distillery waste mixture
(Kyambogo University (Unpublised work), 2023-11) Aguma, Patrick
The use of various wastes in clay for brick making has significantly gained research attention. This is because most of these wastes especially organic ones burn during firing leaving pores (voids) in the bricks thus lowering heat flow across such bricks. In this case, bricks can act as insulators in walls thus cutting energy costs in buildings. In this study, the coefficient of thermal diffusivity of bricks made from clay and local distillery waste mixture was investigated. Local distillery waste is the end waste obtained when the crude brew is made from cassava flour mixed with water, fermented, roasted, dried, fermented again, and distilled. The proportion of clay replaced by the local distillery waste in the mixture was 0, 4, 8, 12, 16, and 20 wt.%. The bricks were then fired from 600-1100 °C in steps of 100 for one hour in an electric furnace. The coefficient of thermal diffusivity was calculated from the experimental values of; thermal conductivity which was measured using quick thermal conductivity meter (QTM-500) with sensor probe PD-11, specific heat capacity which was measured by method of mixture and density obtained from measured values of mass and volume of the samples. The study results presented a general decrease in the values of the coefficient of thermal diffusivity as the content of local distillery wastes added to clay increased across all temperatures. The coefficient of thermal diffusivity was observed to steadily decrease from firing temperatures 600 °C through to lowest values at 900 °C. However, there was an increase in the coefficient of thermal diffusivity in a range of 1000 to 1100 °C. An optimal value of 2.36×10-7 m2s-1 at 900 °C was exhibited by samples with 16 wt.% local distillery waste. This value is below the accepted standard of 5.61×10-7 m2s-1. Therefore, local distillery waste is suitable for use in bricks as thermal insulating material
Activity levels of gamma ray emitting radionuclides in food crop samples in selected tobacco farming areas in Aura and Maracha districts
(Kyambogo University (unpublished work), 2017-12) Anguani, Epiphany Mike
The farming activities, especially Tobacco production in Terego East and Terego West in Arua district and Maracha East County in Maracha district employ fertilizers such as NPK, DAP, CAN, TSP and UREA to enhance soil fertility property and to increase Tobacco production. Fertilizers are known to contain radionuclides such as uranium, radium, potassium etc., that originate from phosphate rocks; that could accumulate in the soil over the years and these may be absorbed by food crops grown on such soils. Humans who feed on these food crops may then absorb such radionuclides. As Human cells absorb radiation energy, molecules in them get damaged resulting into malfunction of cells through genetic mutation and this can then be a health risk. in this study the specific activity levels of gamma ray emitting radionuclides in selected food crop samples (maize, rice, sorghum, cassava, ground nuts, beans and simsim), grown in soils contaminated by fertilizers was determined using Gamma ray spectroscopy technique, that uses Nal(Tl) detector. The samples were obtained from the six Sub Counties of Omugo, Aii-vu, Odupi, Oriama, Katrini and Bileafe in Arua District and three Sub Counties of Tara, Yivu and Nyadri in Maracha District. The sampling technique used was purposive and simple random. In summary, the mean specific activity levels of radium, thorium, uranium and potassium were 64.0 Bqkg·1 , 6.0Bqkg·1, 3.5 Bqkg·1 and 185.1 Bqkg·1 respectively, in the crop samples considered. The mean specific activity levels for potassium was the highest, followed by radium, thorium ·and the least level shown by uranium. The mean absorbed dose rate was 40.9 nGy/h and the mean annual effective dose rate was 0.1 mSv/yr., for all the crop samples considered. The mean annual effective dose rate for all crop samples determined in this study were within the range recommended by the International Atomic Energy Agency as having no observable effects in the human body. Therefore it is recommended that consumption of the food crops investigated should continue as it poses no potential radiation hazard. It is further recommended that investigation should be performed on other crops which are not investigated in this study.
Antecedents for improving physics teachers’ effectiveness in Uganda : a case of Kigezi sub-region
(Kyambogo University (Unpublished work), 2024-11) Tukamuhabwa, Evaristo
Science teachers were an important component of Uganda’s education system because they contributed to the realisation of policy goals of science, technology, engineering and mathematics. Despite that importance, the academic performance of students at UCE in Physics had been perennially poor for decades. To reverse this trend, the SESEMAT programme was introduced to improve the teaching of science subjects in Uganda and consequently, academic performance. The goal of the intervention was in response to several studies before then that had attributed the declining academic achievement in science subjects to ineffective teaching. However, even after the introduction of the SESEMAT programme, academic achievement in the science subjects had not improved either, Kigezi sub-region inclusive. For that reason, this study focused on assessing the aspect of teacher effectiveness since it determined the academic achievement. Thus, the purpose of the study was to assess the antecedents for improving Physics teachers’ effectiveness in Uganda: A case of Kigezi sub region. Specifically, the study aimed at: - establishing the relationship between pedagogical approach antecedents and Physics teachers’ effectiveness; finding out the relationship between school environment antecedents and the Physics teachers’ effectiveness; and, ascertaining if the school environment moderated the relationship between pedagogical approaches and Physics teachers’ effectiveness. The study was anchored on Social Constructivism Theory and Social Ecological Systems Theory. Then the Pragmatism paradigm informed the study, leading to the use of mixed-methods approach and embedded/nested in the mixed-methods research design. In addition, both government aided and private-owned schools were involved. The study involved 214 respondents comprising 194 teachers, 6 District Education Officers and 14 head teachers. In that case, quantitative data was collected from teachers using questionnaires while qualitative data from head teachers and District Education Officers was collected using interviews. More qualitative data was generated through classroom lesson observation and focus group discussions with Heads of Department. The data was analysed quantitatively, using descriptive and inferential statistics; and qualitatively, using content analysis. The results showed a significant positive influence of SESEMAT pedagogical approaches on teacher effectiveness (β=0.348, p<0.001); a positive significant influence of school environment and Physics teachers’ effectiveness (β=0.596, p<0.001); and, a positive significant moderating influence of school environment on the interplay between SESEMAT pedagogical approaches and the Physics teachers’ effectiveness (β=0.275, p<0.001). It was concluded that the SESEMAT pedagogical approaches influenced the teaching effectiveness; the school environment influenced the teaching effectiveness; and the school environment moderated the influence of pedagogical approaches on teaching effectiveness. The study recommended a need: for instructional supervision by the head teachers; for ensuring regular workshops and trainings of science teachers by the government for improved teaching; for school administrators to provide minimum teaching materials; for vestibule training opportunities for benchmarking and creation of teacher development schemes, among others. Above all, the study added value to the existing body of knowledge on curriculum interventions and school outcomes by exploring the moderating influence of school environment. This provided enriched information for informing educational policy-makers.
Assessment of indoor radon concentrations and exposure dose in selected occupational buildings and dwellings in Kampala Capital City Authority, Uganda
(Kyambogo University(Unpublished work), 2025-09) Ssikubwabo, Ivan
Radon exposure is recognised as a serious public health issue resulting from its pronounced effect association with lung cancer, especially in enclosed environments where its concentration can rise significantly. While much of the existing research has concentrated on radon levels in dwelling settings, there is a noticeable gap in studies examining radon exposure in workplaces particularly in fast-developing urban centres like Kampala Capital City Authority. This research aimed to bridge that gap by investigating radon dose levels and assessing the potential radiological risks faced by both employees and inhabitants in selected occupational and dwelling structures located within five administrative divisions of Kampala Capital City Authority. To achieve this, radon levels were monitored at 20 different sites comprising 10 workplaces and 10 dwellings using the Radon Sentinel Model 1030, a continuous radon monitoring instrument. ²²²Rn levels measured in occupational structures varied between 8.7 ± 1.5 to 95.8 ± 8.0 Bq/m³, with a mean concentration of 30.8 ± 4.5 Bq/m³. Significantly elevated readings were observed in storage zones with limited ventilation, where values exceeded the WHO’s recommended ceiling of 100 Bq/m³, reaching a maximum of 194.8 ± 21.2 Bq/m³. In residential buildings, 222 Rn levels spanned from 15.3 ± 2.3 to 188.2 ± 8.2 Bq/m³, with an average of 71.7 ± 17.5 Bq/m³. Several household measurements surpassed the WHO reference threshold. The corresponding annual ED estimates were 0.32 ± 0.05 mSv/year for occupational environments and 0.75 ± 0.18 mSv/year for dwelling settings—both remaining within the internationally endorsed public exposure limit of 1.0 mSv/year. Additional radiological parameters were analysed including the annual equivalent dose to lung tissue, the calculated excess lifetime risk of cancer, and the projected number of LCC attributable to 222 Rn exposure. Overall, the indoor 222 Rn concentrations recorded across the surveyed sites were relatively moderate and are not expected to present substantial health risks. Nevertheless, routine monitoring is advised to account for seasonal fluctuations and maintain long-term radiological safety for occupants of the building.
Characterisation of copper indium gallium diselenide solar module in the Ugandan climate
(Kyambogo University [unpublished work], 2014-01) Kisitu, Zawedde Sarah
The photovoltaic solar energy from copper indium gallium diselenide (CIGS) solar module is one of the most promising sources of solar energy for large scale production of clean energy at competitive prices. The focus of the study was to determine the performance of CIGS solar module in terms of its performance parameters in the tropical region. The goal of this dissertation was hence to characterise the performance of CIGS solar modules in the Ugandan climate. The performance of the CIGS module was assessed when put out doors by measuring the current-voltage (1-V) characteristic of the device. A variable resistor was connected to the CIGS module and was varied from minimum (0 Ω) to maximum (l00 Ω) and the corresponding current and voltage were measured. The electrical performance parameters such as short circuit current, open circuit voltage, maximum power, fill factor and efficiency were then obtained from 1-V characteristic curves. The short circuit current obtained was l.03A that is 1.9% lower than the rated value. The open circuit voltage obtained was 19.25V that is 35.8% lower than the rated value. The maximum current obtained was 0.7 lA that is 12.3% lower than the rated value. The maximum voltage obtained was 13.4V that is 37.9% lower than the rated value. The maximum power obtained was 9.5W that is 36.7% lower than the rated value. There was no change in the fill factor. The efficiency obtained was 6.1 % that is 24.7% lower than the rated value. The study shows that out of the seven parameters it was only the fill factor which had the same value with the rated value. The short circuit current was close to the rated value while other parameters were significantly lower than the rated value varying between 12.3% and 37.9%. Basing on the findings of this study, it is recommended that a further study should be done over a longer period of time for example a year in both dry and wet seasons to cross check the reliability of the findings of this study. The results of this study will be useful to compare the performance of this type of module with others in the market to find out if they would give similar values. Current-voltage (1-V) characteristics measurements under the dark should also be considered to determine the performance of the CIGS solar modules. This would determine other electrical parameters such as series resistance, shunt resistance and diode parameters (ideality factor and reverse saturation current).
Comparison of roki and sunflower oils as sensible heat storage materials for cooking applications
(Kyambogo University [unpublished work], 2022-07) Frank, Mndeme Sayuni
Sensible heat storage materials are cheaper than latent heat storage materials for small storage volumes. Static experiments to evaluate the thermal performances of two Ugandan locally available edible vegetable cooking oils for medium temperature thermal energy storage are presented. The two vegetable oils evaluated and compared are Sunflower oil and Roki oil (a blend of Palm oil and Sunflower oil). Temperature profiles are used to assess the thermal performances during heating cycles, cool-down cycles, energy, exergy, and heat utilization. The results show that Roki oil attains a higher maximum temperature (~ 170 ℃) compared to the Sunflower oil (~160 ℃) during low-temperature heating cycles. Roki oil shows higher temperatures during cooling compared to Sunflower oil, achieving a final temperature (~ 78 ℃) slightly higher than that of Sunflower oil (~ 76 ℃). Roki oil shows a maximum energy rate of 413 W compared to Sunflower oil showing a maximum energy rate of 387 W, this is possibly due to the low thermal mass (mc) of Roki oil compared to Sunflower oil. Roki oil also shows higher maximum exergy rate of ~ 129 W compared to that of Sunflower oil ~ 120 W. This occurs because of the lower thermal mass (mc) of the Roki oil which leads to a quick rise of temperature. The exergy factor of Roki oil (0.31 – 0.62) is slightly higher than Sunflower oil (0.27 – 0.59) within 1 hour and 40 minutes. This is possibly due to the higher difference in temperature of Roki oil compared to Sunflower oil. The heat utilization characteristics of the two heat storage materials are experimentally determined in water heating experiments using 1.0 kg to 3.0 kg water loads. Roki oil shows higher average heat utilization (151 – 350) kJ, and higher average heat utilization efficiency values (0.25 – 0.66) as compared to Sunflower oil (148 – 300) kJ and (0.25 – 0.60), respectively. The average heat utilization and average heat utilization efficiency values increase with the increase in the water load for both Sunflower oil and Roki oil. The best overall performance is shown by Roki oil compared to Sunflower oil. Preliminary results with parabolic dish solar cookers are also presented in this work. The results show that Roki oil performs better than Sunflower oil during heating, cooling/heat retention, and heat utilization.
Compressive strength of concrete produced using aggregates from selected types of rocks in Uganda
(Kyambogo university (Unpublished work), 2024-05) Kawiso, Micah
This study was on determining the compressive strength of concrete made of granite, quartzite and sandstone aggregates of three aggregate sizes of 6.3 mm, 10 mm, and 14 mm and using three cement, sand and aggregate mixture ratios of 1:3:6, 1:2:4, and 1:1:2. This was to find out the effects of mixture ratios, aggregate sizes and aggregate types on compressive strength of the concrete. The samples of concrete were cured for 14 days and then a compression test machine was used to determine the compressive strength of the samples. The average compressive strength of granite concrete of mixture ratios 1:3:6, 1:2:4 and 1:1:2 were 8.56, 19.10 and 32.59 MPa respectively. The mean compressive strength of quartzite concrete of mixture ratios 1:3:6, 1:2:4 and 1:1:2 were 8.78, 17.57 and 31.22 MPa respectively. The average compressive strength of sandstone concrete of mixture ratios 1:3:6, 1:2:4 and 1:1:2 were 9.71, 20.75 and 33.58 MPa respectively. The mean compressive strength of granite concrete of aggregate sizes 6.3, 10, and 14 mm were 18.77, 19.62, and 21.87 MPa respectively. The mean compressive strength of quartzite concrete of aggregate sizes 6.3, 10, and 14 mm were 17.93, 18.95, 20.71 MPa respectively. The mean compressive strength of sandstone concrete of aggregate sizes 6.3, 10, and 14 mm were 19.49, 21.01, 23.21 MPa respectively. The results have revealed that the compressive strength of granite, quartzite and sandstone concrete increased with increase in cement aggregate ratio. Mixture ratio 1:1:2 produced the highest compressive strength of concrete and mixture ratio 1:3:6 produced the lowest compressive strength of concrete. The results have further revealed that compressive strength of the three rock types increased with increase in size of aggregate. The difference in the compressive strength for the three different types of rocks was negligible. Therefore, mixture ratios and aggregate sizes affect concrete compressive strength but rock types used did not affect the compressive strength of concrete samples. Builders and engineers who wish to construct structures should mind most about the aggregate size and mixture ratio than the granite, quartzite or sandstone aggregates used.
Determination of radiological hazard levels in soil, mine tailings and rock samples from selected gold mines in Busia district, Uganda
(Kyambogo University(unpublished), 2018-11-15) Eling, Jimmy
This study was designed to determine radiological hazard levels in soil, mine tailings and rock samples from Agata, Okame, Busia 90 and Greenstone Resource Limited Gold mines in Busia District. The specific activity of the radionuclides were determined using Nal (Ti) scintillation detector and the values were then used to determine the radiological hazard parameters due to radionuclides in the samples from the mines under study. The specific activity of 238U in soil, mine tailings and the rock samples from the four gold mines ranged from 18.7 Bqkg-1 to 27.9 Bqkg-1 , 7.4 Bqkg-1 to 13.2 Bqkg-1 and 1.7 Bqkg-1 to 27.8 Bqkg-1 respectively. The specific activity of 232Th in soil, mine tailings and rock samples from the mines ranged from 60.8 Bqkg-1 to 98.8 Bqkg-1 , 25.1 Bqkg-1 to 32.7 Bqkg-1 and 2.3 Bqkg-1 to 66.6 Bqkg-1 respectively while that of4°K in soil, mine tailings and rock samples ranged from 53.6 Bqkg-1 to 211.8 Bqkg-1 , 5.7 Bqkg-1 to 217.3 Bqkg-1 and 2.1 Bqkg-1 to 120.1 Bqkg-1 respectively. The Specific activity values of 232Th in soil sample from each of the four gold mines were above the worldwide average value of 30 Bqkg-1 . It is only Greenstone mine tailings and Okame rocks that had higher activity for 232Th than the world wide average value. The Absorbed Dose rates in soil, rock and mine tailings samples ranged from 41.7 nGyh-1 to 76.3 nGyh-1 , 13.3 nGyh-1 to 32.7 nGyh-1 and 2.3 nGyh-1 to 58.0 nGyh-1 respectively. Only Okame had a higher value for soil than the world wide average value of 60 nGyh-1 • The Annual Effective Dose rates in soil, mine tailings and rock samples ranged from 0.051 mSvy-1 to 0.093 mSvy-1 , 0.024 mSvf1 to 0.050 mSvf1 and 0.011 mSvy-1 to 0.047 mSvf1 respectively which were lower than the ICRP recommended value of 20 mSvf1 • The internal hazard indices in soil, mine tailings and rock samples ranged from 0.30 to 0.56, 0.15 to 0.27 and 0.02 to 0.43 respectively. External hazard indices of the radionuclides in the soil, mine tailings and rock samples ranged from 0.27 to 0.47, 0.10 to 0.23 and 0.01 to 0.36 respectively. They were found to be below unity as per ICRP, 2007 maximum permissible limit. The Excess Lifetime Cancer Risk (ELCR) ranged from 6.90x10-5 to 1.93x104 was lower than the ICRP maximum permissible excess lifetime cancer risk limit of 5.60x10-2 . Despite the low radiological health risk, miners need protective gears particularly at Okame and Greenstone mines and further research need to be done to validate these findings.
Determination of radiological hazard levels of gammma rays from radionuclides in water from selected boreholes in Moroto district, Uganda
(Kyambogo University (Unpublished work), 2021-03) Okello, Sam
This study was designed to identify gamma ray emitting radionuclides using the GDM 20 NaI(Tl) detector and to determine and compare the activity concentrations, absorbed dose rates, annual effective dose equivalent and the internal and external radiological hazard levels of gamma rays from radionuclides in water from boreholes in four sub counties of Rupa, Katikekile, Nadunget and Northern Division of Moroto District. The radionuclides of 226Ra and 232Th were found in water samples from all the boreholes of the four sub counties. The radionuclide of 40K was only found in two boreholes, three boreholes and five boreholes of Rupa, Katikekile and Nadunget respectively. None was found in the boreholes from Northern Division. The activity concentration of 226Ra exceeded the world average value of 35 Bql-1 in three boreholes of Rupa and Northern Division; in four boreholes of Katikekile and in all the seven boreholes of Nadunget. The activity concentration of 232Th was found to be less than the world average of 30 Bql-1 in all the water samples from all the regions. The activity concentration of 40K was found to exceed the world average of 400 Bql-1 in all the water samples from all the regions. The absorbed dose rates was found to be greater than the world average of 84 nGyh-1 for water samples from two boreholes of Rupa and Northern Division; in five boreholes of Katikekile and in six boreholes of Nadunget. The annual effective dose equivalent was found to be lower than the world internal exposure limit of 0.41 mSvy-1 in all the water samples analyzed. The internal radiological hazard level was found to exceed the permissible value of 1.00 (unity) only in one borehole and three boreholes in Katikekile and Nadunget respectively. The external radiological hazard level was found to exceeded the permissible limit in one borehole from Nadunget; and equal to 1.00 the permissible limit in one borehole from Katikekile. However activity concentration of 226Ra and 40K exceeded the world average value in seventeen boreholes and ten boreholes respectively. While 232Th activity concentrations in all boreholes were below the world average value. It is recommended that a similar study should be carried out to check the results of this study and to find the excess life time cancer risk on the populace that use the water especially those that show high activity and hazard levels. The scope of the study for later studies should be extended to more boreholes.
Determination of the characteristics of solid fuel developed from a mixture of thermoplastic wastes and clay materials
(Kyambogo University(Unpublished work), 2021-03) Oballim, Terence
This study was driven by the fact that plenty of plastics which have potentials to be used as source of fuel are left as wastes in the environment without proper utilization. The study was directed toward the use of a particular type of plastics for making a plastic based solid fuel and to find its viability for use as source of energy. Polyethylene – terephthalate (PET) material obtained from waste mineral water bottles and ball clay were mixed to form PET – Clay Solid Fuel (PETCSF) product. Clay was mixed with plastics to avoid melt flowing or dropping of the fuel in the stove during combustion. The parameters of the developed PETCSF those were determined to find its viability as source of energy were Mass of melt drops, mass combustion rate, mass of ash and the calorific value. The following Clay Plastic Ratio (CPR) 1:2.43, 1:2.33 and 1:1.20 were found to be sufficient in stopping melt dropping behavior of the developed solid fuel in the stove during combustion. The calorific values of the PETCSF were found to be 14,335 J g-1, 14,170 J g-1 and 11,182 J g-1 for CPR = 1:2.43, 1:2.33 & 1:1.20 respectively. Calorific values of an equal mass of charcoal, paper and Benzoic acid tablet (used as reference solid fuel materials) were 7,316 J g-1, 12,475 J g-1 and 24,239 J g-1 respectively. The mass combustion rates for CPR = 1:2.43, 1:2.33 & 1:1.20 were found to be 2.45 g minute-1, 2.43 g minute-1 and 1.98 g minute-1 respectively. The mass of ash left after combustion for the above respective CPR values were 36.64 g, 37.37 g and 50.73 g respectively. When compared, the calorific value of the developed PETCSF was found to be about two times higher than for charcoal of an equal mass. Benzoic acid tablet had the highest calorific value. Thus, PETCSF is a viable source of fuel compared to charcoal in terms of the calorific value and moreover its combustion rate can be controlled by using a specific CPR of 1:2.43 as shown by the result of the study. The population should be encouraged by the findings in this study and to begin thinking of using plastic based solid fuel as an alternative to charcoal and firewood which currently are the only predominant sources of fuel for majority of the population. The used plastic based solid fuel in an oxygen rich environment (or sufficient air circulation) is strongly recommended as complete combustion is guaranteed. Insufficient air supply may lead to incomplete combustion of the fuel and possibly release of particles (soot/smoke) which if inhaled may be harmful to the user.
Determination of thermal diffusivity of fired clay bricks produced from cow pie mixed with selected Ugandan clays
(Kyambogo University [unpublished work], 2023-05) Kansiime, Evalyne Mary
This study was designed to determine the thermal diffusivity of fired clay samples produced by mixing cow pie with clays from selected districts in Uganda. The focus of the study was to find out the effect of clay particle sizes and the ratio of kaolin clay, ball clay and cow pie on thermal diffusivity. The clay particle sizes considered were 0-74, 75-89, 90-149, 150-299 and 300-349 μm, the cow pie particle sizes considered were 75-149 and 150-299 μm and the clay-cow pie ratios considered were 9:7:4, 9:6:5 and 9:7:0. The samples used in the study were compacted by using a compression machine International, England at a pressure of 50 MPa and were fired in a heating chamber (CARBOLITE, GERO, HTF 1700) up to a temperature of 950 0C at different firing rates of 1.2 0C/s, 1.3 0C/s, 1.5 0C/s and 0.5 0C/s. Thermal conductivity was measured by using a QTM-machine, density was obtained from mass per unit volume and specific heat capacity was obtained by using a simple calorimeter and applying the method of mixtures. The average values obtained for the thermal properties in the order of increasing particle sizes were as follows; for the kaolin: ball clay: cow pie ratio 9:7:4, thermal conductivity values were 0.2254, 0.2210, 0.2214, 0.2204 and 0.2195 Wm-1K-1, density values were 1.1800, 1.1535, 1.1537, 1.1433 and 1.1490 gcm-3, specific heat capacity values were 1.0670, 1.0510, 0.9810, 1.0490 and 1.0100 Jg-10C-1, the average calculated thermal diffusivity values were 0.1924 e -6, 0.2021 e-6, 0.1883 e-6, 0.2441 e-6, and 0.2039 e-6 m2s-1, for the kaolin: ball clay: cow pie ratio 9:6:5 thermal conductivity values were 0.2237, 0.2221, 0.2188, 0.2200 and 0.2178 Wm-1K-1, density values were 1.1866, 1.1661, 1.1945, 1.1789 and 1.2002 gcm-3, specific heat capacity values were 1.0490, 1.0810, 1.0630, 1.0450 and 1.0020 Jg-10C-1, the average calculated thermal diffusivity values were 0.1919 e-6, 0.2005e-6, 0.2046 e-6, 0.2080e-6, and 0.2031 e-6 m2s-1 and for the kaolin: ball clay: cow pie ratio 9:7:0, thermal conductivity values were 0.2871, 0.2781, 0.2771, 0.2654 and 0.2654 Wm-1K-1, density values were 1.1685, 1.1578, 1.1379, 1.1450 and 1.1280 gcm-3, specific heat capacity values were 1.0690, 1.0490, 1.0460, 1.0200 and 1.0510 Jg-10C-1, the average calculated thermal diffusivity values were 0.2546 e-6, 0.2439 e-6, 0.2427 e-6, 0.2466 e-6, and 0.2254 e-6 m2s-1. From the results, thermal diffusivity increased with the decrease in particle sizes of kaolin and ball clay; however, it was lower for the ratio 9:6:5. Thermal diffusivity values for the control experiment were very high and this implies that cow dung was a good pore former and should be incorporated into clay bricks to improve on their thermal insulation.
Gamma radiation exposure levels due to radionuclides in soils from selected gold mines in Karamoja
(Kyambogo University(unpublished work), 2016-01) Chelangat, Kadafi
The aim of this study was to determine radiation exposure levels due to gamma ray emitting radionuclides in soils from selected gold mines in Karamoja and the associated hazard indices. The people of Karamoja use poor methods of mining gold, therefore they are exposed to ionizing radiation of unknown concentrations. In this study, 60 samples from Rupa, Nakabaat, Morulem, Acerer, Nabulatuk and Morita were analysed using a Nal (TI) gamma-ray detector. The activity concentrations of natural radionuclides 226 Ra, 232 Th, 238 U and 4° K in soils were measured by gamma spectroscopy using sodium iodide detector. In addition, radiological assessment due to these radionuclides was also carried out. To ensure quality control, the samples collected from the sites were transferred to polythene bags, labeled and double-bagged. They were transported in boxes whose background radiation emissions were measured with an identifier. The average activity concentrations of 226 Ra, 232 Th, 238 U and 4° K were 49.26 ± 1.58, 44.29 ± 0.74, 16.57 ± 0.40 and 599.64 ± 7.33 Bqkg-1 respectively. The mean absorbed dose rate was 50.44 ± 1.48 nGhr-1 which is below the world average dose rate of 60 nGhr-1 • Radium equivalent values for the area studied ranged from 83 .83 ± 2.33 to 186.12 ± 3.52 Bqkg-1 with mean of 117.22 ± 2.30 Bqkg-1 which is below the world average of 370 Bqkg-1 • The mean external and internal hazard indices were both below unity. Therefore, though the results in the study indicated higher levels of natural radionuclides in soils of Karamoja region than the world average values, the mining activities pose no significant radiological hazard to the population and the soils from these areas can be safely used for construction purposes. The observed unprofessional practices such as lack of use of gas masks while working in the dust-filled mine caves could expose workers to possible risks from inhalation of respirable crystalline silica and radon gas; therefore miners must be educated and sensitized on the effects of exposure to radiation by the Atomic Energy Council of Uganda. These can be done by introducing Safety and Health awareness days. People of Nabulatuk and Acerer in Nakapiripirit district where concentrations of radionuclides are twice the world average levels must be advised to reduce on the time they spend in mines.
Gamma ray activity levels and radiological hazard indices of Radionuclides in mine tailings from selected mines in Southwestern Uganda.
(Kyambogo University [unpublished work], 2016-01) Turyahabwa, Evarist Rutahweire Silver
This study was designed to determine and compare the specific activity levels and the radiological hazard indices of gamma ray emitting radionuclides in mine tailings from three selected mines in Southwestern Uganda. This was achieved by analyzing 72 soil and rock mine tailing samples using the GDM 20 Nal(TI) detector. The specific activities of the principal primordial radionucides of 238U, 232Th and 4°K in the samples were measured. The values obtained were used to determine the absorbed dose rates, the annual effective dose rates, the radium equivalent activity, external and internal hazard index and the excess lifetime cancer risk. The mean specific activities of 238U, 232Th and 4°K in mine tailings at 90% confidence level ranged from 23±14 Bqkg-1 to 59±16 Bqkg-1 for 238U, 49±39 Bqkg-1 to 244±19 Bqkg-1 for 232Th, and 226±232 Bqkg-1 to 893±167 Bqkg-1 for 4°K. The mean outdoor and indoor absorbed dose rates in air for Mashonga, Kikagati and B utare were (181±36 nGyh-1 and 338±67 nGyh-1 ), (167±23 nGyh-1 and 310±47 nGyh-1 ) and (192±16 nGyh-1 and 355±32 nGyh-1 ) respectively for waste soil samples and (67±50 nGyh-1and 127±102 nGyh-1 ), (85±37 nGyh-1 and 159±80 nGyh-1 ) and (115±33 nGyh-1 and 215±66 nGyh-1 ) respectively for waste rock samples. The ratio of the mean indoor to outdoor absorbed dose rates in all the samples was 1.9 but this was 36% higher than the world average. The total annual effective dose rates, radium equivalent activities, external and internal hazard indices for waste soil samples were above the maximum permissible limits recommended for members of the public. Potential radiological hazards on miners and the people living in the neighborhood of the sites due to external irradiation are significant. There is need to improve waste management practices in the mining sites in order to prevent health hazards associated with the radionuclides in the mine tailings.
Green synthesis of copper oxide nanoparticles from pumpkin (Cucurbita maxima) dye extract: a platinum free counter electrode for dye sensitized solar cells
(Kyambogo University (Unpublished work), 2024-02) Tenywa, Stephen
Energy is a very critical requirement for all nations that boosts economic growth and development. Dye-sensitized solar cells (DSSCs), the 3rd generation photovoltaic technology which imitate the process of photosynthesis in green plants have of recent gained overwhelming attention in solar harnessing because of their simple structure, affordable cost, simple fabrication technique, little toxicity, and comparatively high efficiency of energy conversion. Currently, Platinum is used as a counter electrode for DSSCs. However, the scarcity and high cost of Pt is still a challenge. In this study, copper oxide (CuO) nanoparticles (NPs) were synthesized using Cucurbita maxima plant leaf dye extract and applied as an electrocatalytic CE in DSSCs. The CuO NPs were characterized using XRD, TEM, UV-Visible spectrophotometer and FTIR to obtain their crystal structure, surface morphology, optical properties and chemical bonds respectively. Three individual natural dyes from pumpkin leaves (P), sweet potato leaves (S) and hibiscus flowers (H), along with their composites, P:H and S:H in varying ratios were extracted, their optical properties studied and used as photosensitizers. The results indicate that the fabricated DSSC with P:H-1:3 composite dyes yielded the highest PCE of 8.7×10-4 %, a short circuit current density (Jsc) of 13.94 μA/cm2 and an open circuit voltage (Voc) of 0.29 V compared to S:H-1:3 composite and individual dyes under one-sun illumination from a solar simulator (AM1.5 100 mWcm-2).
Infra-red reflectance and transmittance by thin film coatings of some selected metals on glass substrate
(Kyambogo University(unpublished), 2018-11-14) Kamwasir Hellene
Reflection and transmission of light serve as key parameters in thin films coatings meant for temperature regulation in warm climates. In this study, the infrared reflectance and transmittance for three different thicknesses of thin films of palladium and platinum were determined. The thin films were made by thermally evaporating various masses of the platinum and palladium on glass substrates. A Shimadzu UV-VIS-NIR Spectrophotometer was used to determine the reflectance and transmittance of the samples from which the spectra were determined. Ex situ measurements, using Point wise Unconstrained Minimization Approach (PUMA) were made to determine the exact thicknesses of the films. Reflectance was found to vary with film thickness. The results showed that the 60 nm film of palladium had a maximum reflectance of 33%, 140 nm film, a maximum reflectance of 39% and 230 nm film, a maximum reflectance of 72%. For platinum, the 140 nm film had a maximum reflectance of 28%, 146 nm film a maximum of 35% and 395 nm film a maximum reflectance of 42%. In all the cases, the reflectance in the infrared part of the spectra (800-2500 nm) was higher than in the visible region which suggests that palladium and platinum thin films may be used as heat mirrors. The transmittances of palladium and platinum thin films were high (over 80%) an indication that the thin films probably had voids. The study also showed that for the same thickness of palladium and platinum films (Palladium film of 140 nm and platinum film of 140 nm), palladium has greater reflectance than platinum showing dependence of reflectance of thin film on material used for its fabrication.
Intensity of secondary scattered x-rays during x-ray diagnostic procedures in selected diagnostic centres in Uganda
(Kyambogo University[unpublished work], 2014-01) Byaruhanga, Bonaventure
The purpose of the study was to investigate the intensity of secondary scattered X-rays when different body regions; the chest, the abdomen and the lower limbs were exposed to X-rays during radiography. The study used experimental design where the secondary scattered X-ray dose from three diagnostic centres in South Western Uganda were measured us.ing TLDs that were worn at the back of the radiographer. The cards were then read monthly and the process repeated for a period of six months. The number of patients exposed to X-rays for each procedure for the same period was also noted. From the study, it was found that the limb exposures constituted the highest proportion of the patients X-rayed (42%), followed by the chest· (35%) and finally the abdomen (23%). In addition, it was found that the chest exposures generally lead to the highest intensity of secondary scattered X-rays to the radiographers which was 2,670 mSv, 2,756 mSv and 2,505 mSv for Mutolere Hospital, Goodwill Imaging Centre and Mbarara Diagnostic Centre respectively. The limbs contributed the second highest intensity of secondary scattered X-rays (2,442 mSv) at Mutolere Hospital, though generally the abdomen contributed the second highest secondary scattered X-rays (1,712 and 1,294 mSv for Goodwill and Mbarara Diagnostic Centre respectively). The limbs contributed the lowest intensity of secondary scattered X-rays in Goodwill and Mbarara Diagnostic Centre i.e 1,578 and 1,236 mSv respectively. In relation to the safety standards set by the International Atomic Energy Agency ( IAEA, 2002), the predicted cumulative annual dose to radiographers from Mutolere Hospital, Goodwill Imaging Centre and Mbarara Diagnostic Centre are 13,704, 11,964 and 10,692 mSv respectively. These values are below the annual dose limit of 20 mSv for radiation worker as recommended by IAEA (IAEA, 2002). This means that the radiographers from the three diagnostic centres are at a low risk of developing stochastic health effects. However, the annual dose from the diagnostic centres could be dangerous if radiographers are exposed over many years in a lifetime.
Investigation of mechanical properties of ceramic tiles developed from selected clay deposits in Uganda
(Kyambogo University [unpublished work], 2023-10) Mukwaya, George William
In this study the characteristics of Buwambo kaolin, Lunya feldspar, Ntawo ball clay and Liddo beach sand were determined. The Modulus of Rapture (MOR) and Compressive Strength (CS) of the tiles produced using kaolin:feldspar of different composition ratios were determined. The composition ratios of kaolin:feldspar used were 4:3, 3:4, 5:9 and 2:5 by mass. On the other hand, a fixed composition ratio was used for ball clay:sand of 5:1 by mass (Ochen et.al 2012). The samples were fired at 1100 0C for 8 hours. Using the scanning electron microscope (SEM), the Buwambo kaolin had a porous cellular structure of irregular-shaped particles of average size of 0.202 ± 0.131 μm. Liddo beach sand had porous particles with average particle size of 0.168 ± 0.198 μm, the Lunya feldspar had irregular confined particles with average particle size of 0.153 ± 0.105 μm and the Ntawo ball clay had fine grained uniform rounded particles of average size of 0.095 ± 0.055 μm. X-ray fluorescence (XRF) and Energy dispersive x-ray (EDX) spectroscopy were used to determine the elemental composition. The XRF on Liddo beach sand showed that it is mainly composed of 99.5 % SiO2 with trace amounts of Al2O3 and Fe2O3 each 0.2 %. The EDX revealed that Buwambo kaolin mainly had 11.15 % Aluminium and 10.83 % Silicon. The Lunya feldspar mainly had 19.53 % Silicon and 5.46 % Sodium. The Ntawo ball clay mainly had 12.91 % silicon and 4.52 % aluminium. X-ray diffraction (XRD) on Liddo beach sand showed a broad reflection peak at 2θ = 22.86 o indicating its amorphous nature. The Lunya feldspar showed major peaks at 20.69, 26.40 and 29.52 o which are within the acceptable range of sodium feldspar. The Ntawo ball clay showed major peaks at 2θ = 20.82, 26.53 and 27.35 o. For Buwambo kaolin, the major peaks were located at 2θ = 12.29 and 27.40 o. The MOR and CS were significantly dependent on composition ratios at significant levels α = 0.01 and α = 0.05 and therefore the null hypotheses that the CS and MOR of the tiles produced are not affected by the composition ratios of the clay mixture rejected at the two levels of significance. The sample with the highest kaolin-feldspar ratio of 4:3 had the highest MOR of 30.84 ± 2.67 MPa at α = 0.01 and 30.84 ± 1.60 MPa at α = 0.05. It also had the highest CS of 1.36 ± 0.06 MPa at α = 0.01 and 1.36 ± 0.04 MPa at α = 0.05. Similarly, the sample with the lowest kaolin-feldspar ratio of 2:5 had the least MOR of 18.58 ± 0.51 MPa at α = 0.01 and 18.58 ± 0.31 MPa at α = 0.05. It also had the least CS of 0.82 ± 0.03 MPa at α = 0.01 and 0.82 ± 0.02 at α = 0.05. Further investigation should be carried out using other clay deposits to find out how the variation in the amount of kaolin and feldspar in them would affect the CS and MOR of tile samples developed using these clays.
Investigation of mechanical properties of concrete developed from a binder composite of sugar cane bagasse ash and Portland cement
(Kyambogo University (Unpublished work), 2024-10) Nzugua, Michael Evans
Cement production has been growing over time. Statistics indicate more growth as the human population increases. However, cement production relies on natural resources such as limestone rocks. The mining of these minerals poses grave environmental hazards. Increased limestone mining and its use in cement production have led to, deforestation, soil and water contamination and greenhouse gas (GHG) emissions mostly carbon dioxide (CO2). This has led to global warming and the rising of sea levels. The East Africa Community (EAC) countries have immense sugarcane cane bagasse ash (SCBA) which remains unexploited as a supplementary-cementitious material (SCM). This study delved into using EAC SCBA as a pozzolan. SCBA investigated was collected from Kenya's coastal area. Raw SCBA, processed SCBA, Portland cement (PC) and the developed concrete were characterised by various techniques to determine the surface morphology, chemical composition, structural properties and mineralogical composition. The raw SCBA was calcinated at 600 oC to get processed SCBA (SCBA-600). SCBA-600 was then used to design the concrete mix. PC was replaced from 0 to 30 % in steps of 10 %. The flexural and compressive strengths were determined in the hardened state after twenty-eight days of concrete curing. The compressive and flexural strength of the mix containing 20 % SCBA was higher than the control mix by 9.65 and 6.51 %, respectively. The microstructural properties of the developed concrete revealed dense particle distribution, indicating good micro/nanofiller effects of the interfacial transition zone. The processed SCBA was found to meet class N and F of natural pozzolan as per ASTM –C 618. The samples were analysed using XRD, SEM, EDX, and XRF techniques. The concrete design was done following IS 10262-2009 and IS 456. The casting and curing were done as per ASTM C-192 and lastly, the mechanical strengths were done as per ASTM C-39 and ASTM C78-00 standards specifications. These positive results from the experimental investigation, technically portray the Kenya coastal SCBA as a potential SCM.
Investigation of power conversion efficiency of a dye-sensitized solar cell fabricated using green-synthesized zinc oxide nanoparticles as photo-anode
(Kyambogo University (Unpublised work), 2025-09) Balabye, Stephen
Green synthesis, a biological method for nanoparticle preparation, has been suggested as a possible eco-friendly alternative to chemical and physical methods. In this study, green synthesis of zinc oxide (ZnO) nanoparticles (NPs) from Erythrina abyssinica stem bark extract calcined under different temperatures (300-700 ℃) for application as a photo-anode in dye sensitized solar cells (DSSCs) was carried out. Synthesized ZnO Nps were subjected to characterization using X-Ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Visible (UV-Vis) Spectroscopy and photo luminescence (PL) analysis. The analysis revealed that highly crystalline hexagonal ZnO NPs were formed at 700 ℃, with the nanospheres agglomeration into non-uniform distinct NPs with a band gap energy of 3.12 eV. An efficient dye sensitized solar cell (DSSC) was fabricated with synthesized ZnO Nps as photo- anode materials. The fabricated DSSC showed an open circuit voltage (Voc) of 161 mV, short circuit current density(Jsc) of 56 μAcm-2, a Fill factor of 0.265 and a power conversion efficiency (PCE) of 2.4×10-2 % under one sun illumination. The low value of efficiency can be attributed to the limited light absorption in the visible spectrum by the ruthenium N719 dye adsorbed on the biosynthesized ZnO nanoparticles, and fast electron-hole recombination rate. Further research should be focused on improving the light absorption range of Ru N719 dye adsorbed on biosynthesized ZnO nanoparticles and minimizing the charge recombination rates through doping and heterostructuring.
Investigation of radon concentration and annual effective dose in selected caves in kakumiro and fort portal, western Uganda
(Kyambogo University (Unpublished work), 2024-02) Tusiimire, Anitah
This study was conducted to determine radon concentration and annual effective dose in Amabere Ga Nyinamwiru cave and Semwama hill cave in Western Uganda using continuous radon monitor (Radon Sentinel model 1030). The radon concentration levels in Amabere caves for morning period (7:00-10:00), mid-morning period (10:00-1:00) and afternoon period (1:00- 4:00) varied from 14.27 ± 4.01 Bqm-3 to 17.70 ± 01 Bqm-3 with mean value of 15.90 ± 2.76 Bqm-3. The radon concentration in Semwama hill cave for morning period (7:00-10:00), mid-morning period (10:00-1:00) and afternoon period (1:00- 4:00) was found to vary from 447.3 ± 30.64 Bqm-3 to 507.63 ± 30.64 Bqm-3 with a mean value of 480.56 ± 30.64 Bqm-3. The annual effective dose for Amabere caves varied from 0.36 ± 0.10 mSvyr-1 to 0.44 ± 0.08 mSvyr-1 with an average value of 0.40 ± 0.07 mSvyr-1. The annual effective doses for Semwama hill cave ranged from 11.27 ± 0.77 mSvy-1 to 12.27 ± 77 mSvy-1 with mean value of 12.11 ± 0.77 mSvy-1. The Semwama Hill Cave effective dose data show that there is evidence of radon health risk to the general public and workers, as most of the values of yearly effective doses determined are more than 1 mSvy-1 as advised by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), International Commission on Radiological Protection (ICRP), and World Health Organization (WHO). Semwama hill cave, which has limited ventilation, has higher radon concentrations than Amabere caves. Further studies should be carried out on Semwama hill cave to ascertain the exposure levels to 222Radon gas as compared with a broad baseline measurement and future research should also look at the seasonal variations in the cave's radon concentration, equilibrium factor, and aerosol state, as well as an analysis of the tour guides' time spent there.

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