http://ir.library.ui.edu.ng/handle/123456789/421 Theses Fri, 03 Apr 2026 19:54:42 GMT 2026-04-03T19:54:42Z http://ir.library.ui.edu.ng/handle/123456789/4759 Title: SOME ASPECTS OF THE ATMOSPHERIC ELECTRIC CLIMATE AT IBADAN Authors: ADEWOLU, D. O. Abstract: The diurnal variations of the atmospheric electric Parameters and meteorological Parameters for the harmattan season of November 1978 to March 1979 are presented. The percentage variations of temperature are mirror images of those of vapour pressure which show pronounced depressions around noon when the little available moisture in the air near the ground is distributed over greater and greater heights by convection. The diurnal patterns of dust concentration, measured for the first time in this locality, is single periodic with minimum between 0400 hrs and 0800 hrs L.T. and maximum around 20 hrs L.T. This pattern is closely related to that of windspeed, and is explained in terms of the copious amount of dust transported southwards from the Sahara desert. The diurnal curves of the electric elements. I, H and p show pronounced “austausch” depressions around noon and marked peaks at 08.00 hrs which are attributable to the sunrise effect. An average value of the total nuclei concentration during the Harmattan months is computed to be about 2.8x10(10) particles per m(3) for this Station. This value is based on the measurements of the polar conductivities made for the first time in Ibadan. Description: A THESIS IN THE DEPARTMENT OF PHYSICS SUBMITTED TO THE FACULTY OF SCIENCE IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHILOSOPHY OF THE UNIVERSITY OF IBADAN Tue, 01 Jul 1980 00:00:00 GMT http://ir.library.ui.edu.ng/handle/123456789/4759 1980-07-01T00:00:00Z http://ir.library.ui.edu.ng/handle/123456789/3841 Title: Luminescence Sensitisation of Natural Quartz Using Pre-Exposure Dose and Thermal Activation Techniques Authors: Oniya, E. O. Abstract: Luminescence sensitisation is an important stage in the application of quartz in pre-dose retrospective dosimetry and dating. The existing techniques for sensitisation in quartz are Pre-Exposure Dose (PED) and Thermal Activation (TA). Previous works were centred on combined actions of PED and TA with less attention given to the separate contributions of these techniques in pre-dose sensitisation of quartz. This work was undertaken to determine the separate contributions of PED and TA in sensitisations of 110oC Thermoluminescence (TL) peak and Room Temperature Linearly Modulated Optically Stimulated Luminescence (RT-LMOSL) of quartz. Two sets of quartz samples, one from Oro in Kwara State (S2) and the other from Ijero-Ekiti, Ekiti State (S4) with high sensitisation signals were used. Each of the two sets was divided into two parts; the first was unannealed while the second part was annealed, following standard procedures. Each of the unannealed and annealed samples was further divided into 38 aliquots required for the protocol. Fourteen aliquots each of unannealed and annealed samples were given PED and another set of 14 aliquots were without PED. The TL and RT-LMOSL measurements were carried out on each aliquot using an automated (model-TL/OSL–DA–15). Sensitisation reproducibility of repeated TL measurements on 10 different aliquots of each of the unannealed and annealed samples was quantified using Coefficient of Variation (CV). Data were analysed using descriptive statistics. reader TL/OSL RISØThe sensitisation signals of the aliquots of unannealed samples without PED was higher than that of the aliquots with PED by factor of 76.0 % and 79.0 % for TL and RT-LMOSL respectively for S2 while the corresponding factors obtained for S4 were 45.0 % for TL and 14.0 % for RT-LMOSL. In annealed samples, the sensitisation signal of the aliquots with PED was rather higher than that of the aliquots without PED, by factor of 224.0 % for TL and 201.0 % for RT-LMOSL for S2 and for S4, it was by factor of 245.0 % for TL and 217.0 % for RT-LMOSL. The sensitisations reproducibility of aliquots of unannealed samples were found to be poor with CV of 33.5 % for S2 and 52.0 % for S4. This improved significantly in the annealed samples to CV 6.3 % for S2 and 9.0 % for S4. Luminescence sensitisation by pre-exposure dose was dominant in annealed quartz samples. Therefore, only annealed quartz samples are recommended for pre-dose retrospective dosimetry and dating. The use of 110oC thermoluminescence peak signal in sensitisation corrections of unannealed quartz is not advisable. Description: A thesis in the Department of Physics Submitted to the Faculty of Science in partial fulfillment of the requirements for the Degree of Doctor of Philosophy of the University of Ibadan Wed, 01 Jan 2014 00:00:00 GMT http://ir.library.ui.edu.ng/handle/123456789/3841 2014-01-01T00:00:00Z http://ir.library.ui.edu.ng/handle/123456789/3840 Title: Radiation Dose Audit of Common X-Ray Diagnostic Procedures of Patients and Implications for Cancer Incidence in Southwestern Nigeria Authors: Olowookere, J. C. Abstract: One of the objectives of x-ray examination is high quality images; however administered radiation doses may be harmful to patients‟ health. Data on radiation dose to patients are scarce, and thus hinder the determination of local and national reference dose levels specific to a country owing to the differences in patient anatomy and radiological practice among nationals of different countries. This study was therefore, designed to determine the patient doses, local reference dose levels and estimate cancer risk based on administered dose at selected radiodiagnostic centres in Southwestern Nigeria. Twelve radiodiagnostic centres were purposely selected across Lagos (3); Ogun (2); Oyo (1); Osun (4) and Ekiti (2) for this study. Exposure parameters including: peak voltage; tube load (mAs); focus-to-skin distance were obtained from x-ray machines during radiographic procedures. Quality control (QC) tests were performed using standard calibration method. Anthropometric data from 689 consented subjects were obtained for chest (353) Postero-Anterior (PA) and Antero-Posterior (AP) for abdomen (20), pelvis (35), skull (56), lumbar spine (87), thigh (12), leg (46), knee (17) and hand (63) examinations. Measurement of Entrance Surface Dose (ESD) was carried out with thermoluminescent dosimeters and converted to Dose-Area Product (DAP). Organ Dose (OD) and Effective Dose (ED) were determined using appropriate software. Organ doses were used to estimate the expected number of cancer incidences resulting from the examinations. Preliminary Local Reference Dose Levels (PLRDLs) were determined, and Patient Parametric-Exposure Estimation (PPEE) models which served as guides in the choice of appropriate exposure parameters for dose optimisation were developed. Data were analysed using descriptive statistics and compared with National Radiological Protection Board levels. The QC results showed that 66.7% of the x-ray machines fall within the internationally acceptable tolerance limit of ±5.0% of exposure parameters reproducibility. The ESD (mGy) for chest PA, abdomen AP, pelvis AP, lumbar spine AP, skull AP, leg AP, knee AP, hand AP and thigh AP were 2.32 ± 0.19, 11.72 ± 2.62, 4.05 ± 0.54, 4.74 ± 0.72, 7.07 ± 0.67, 1.27 ± 0.19, 1.59 ± 0.34 ± 0.19,0.50 ± 0.05; and the DAP (Gy cm2) were 3.06 ± 0.30,17.16 ± 4.96, 3.28 ± 0.47, 2.72 ± 0.44,4.53 ± 0.05,1.15,1.53 ± 0.23,0.92 ± 0.13,0.18 ± 0.02 for chest PA, abdomen AP, pelvis AP, lumbar AP, skull AP, leg AP, knee AP, hand AP and hand AP projections respectively The ED ranged from. The ranges of cancer incidences expected per annum for patients undergoing chest PA examinations for different organs were: lung (227-452), breast (28-207), easophagus (8-26), stomach (28-78) and liver (14-95). The proposed PLDRLs for ESD (mGy) and the corresponding DAP (Gy cm2) were;2.95(3.14), 22.31(28.59), 6.63(4.77), 5.87(3.20), 9.04(5.06), 1.51(2.04), 2.78(2.09), 2.39(1.44), 0.69(0.25) chest PA, abdomen, pelvis, lumbar spine, skull, leg, knee, hand and thigh (AP projections) respectively. The determined PLDRLs were higher than the National Radiological Protection Board reference levels by factors ranging from 1.70-19.70 and 2.20-31.40 for ESD and DAP, respectively. The developed models for estimating patient thickness from weight () were: for standard male and female adults respectively. Patients undergoing selected diagnostic x-ray procedures in Southwestern Nigeria received high doses and have increased risk of cancer. The established local reference levels could help in dose optimisation for radiological practices in Southwestern Nigeria. Description: A Thesis in the Department of Physics Submitted to the Faculty of Science in Partial Fulfilment of the Requirements for the Degree of Doctor of Philosophy (PhD) of the University of Ibadan Fri, 01 Jan 2016 00:00:00 GMT http://ir.library.ui.edu.ng/handle/123456789/3840 2016-01-01T00:00:00Z http://ir.library.ui.edu.ng/handle/123456789/3839 Title: Fabrication and Characterisation of Superstrate Copper Zinc Tin Sulphide (Cu2znsns4) Thin Films Solar Cells Authors: Olopade, M. A. Abstract: Greenhouse gases emitted from burnt fossil fuels are major contributors to global warming which currently threatens existence of life. Hence, the global campaign for the replacement of fossil fuels with solar energy. The Cu2ZnSnS4 (CZTS) thin film has emerged as a promising material for photovoltaic absorption layer in the fabrication of solar cells. Various methods of deposition have been used to fabricate superstrate CZTS thin film solar cells. However, there is limited information on the use of sol-gel method which is known to perfectly control chemical composition for the fabrication of this type of solar cells. In this study, a superstrate structured CZTS thin film solar cell was fabricated using the sol-gel method and thereafter characterised. The possibility of using paper tape during the fabrication process instead of photomask which is not always readily available was also investigated. Superstrate structured CZTS thin film solar cells were fabricated using atmospheric pressure chemical vapour to deposit SnO2:F thin film (as window layer). Also, spin coating method was used to deposit CdS thin film (as buffer layer) from the sol-gel of cadmium acetate, 2-methoxy ethanol, thiourea and polyethylene glycol. Sol-gel sulphurising method was used to deposit Cu2ZnSnS4 thin film (as absorber layer) from CuCl2, ZnCl, SnCl2 and thiourea (as sulphur source). Layers of the film were masked using paper tape, optimised and characterised following standard procedures before being used in the fabrication of (SLG)/FTO (SnO2:F)/Ag/CdS/CZTS/Al solar cell. The deposited films were characterised using scanning electron microscope for surface morphology, Jandel universal four point probe for sheet resistance, MD-10 X-ray Diffractometer for crystallography and AvaSpec-2048 UV-VIS spectrophotometer for optical properties. The CZTS thin film solar cells of active area 2.25cm2 were examined for their efficiencies using the Newport solar simulator under irradiation of 100 mW/cm2. The mean of the efficiencies of CZTS solar cells from sol-gel method were compared with previous work on screen printing and doctor-blade methods. The SnO2:F thin film obtained had a transmittance of 80% in the UV-Visible region of the electromagnetic spectrum and a sheet resistance of 15 Ω/sq which is within acceptable values for a window layer. The calculated energy band gap of the CdS and CZTS films from the transmittance and reflectance data were 2.40 eV and 1.51 eV respectively. This value for CZTS is closest to near-optimal direct band gap value (1.50eV) when compared with those obtained via screen printing (1.40eV) and doctor blade (1.41eV) methods. The X-ray diffraction pattern of the CdS film exhibit hexagonal structure with (002) orientation while CZTS film had kesterite structure with (112) orientation. The absorption co-efficient of CZTS film in the visible region was 104 cm-1. The X-ray diffraction pattern showed sharp peaks whereas broadened peaks were observed in the X-ray diffraction pattern obtained via doctor blade method. The fabricated solar cells with buffer layer thicknesses of 40 nm and 60 nm had efficiencies of 0.28 0.01% and 0.13 0.01% respectively when compared with screen printing (0.53%) and doctor-blade (0.55%). Superstrate Cu2ZnSnS4 solar cells have been successfully fabricated using sol-gel spin coating method and paper tape in lieu of photomask Description: A Thesis in the Department of Physics Submitted to the Faculty of Science in partial fulfillment of the requirements for the Degree of Doctor of Philosophy of the University of Ibadan Tue, 01 Jan 2013 00:00:00 GMT http://ir.library.ui.edu.ng/handle/123456789/3839 2013-01-01T00:00:00Z