Physics

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Physics

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Start date: 2011End date: 2019

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    Effect of Natural Dye Co-Sensitization on the Performance of Dye-Sensitized Solar Cells (DSSCS) Based on Anthocyanin and Betalain Pigments Sensitisation
    (European Journal of Applied Sciences 9 (3): 140-146, 2017 ISSN 2079-2077, 2017-01-01) YUSUF Abubakar Sadiq; K.U. Isah; B.J. Jolayemi
    Dye-sensitized solar cells (DSSCs) were prepared using natural pigments containing anthocyanin and betalain extracted from Flame tree and Bougainvillea glabra flowers respectively as sensitizers. The dyes were used as lone sensitizers exploring anthocyanin and betalain separately and as co-sensitizers exploring the combined anthocyanin and betalain (water extract) and combined anthocyanin and betalain (ethanol extract) separately. The effects of the sensitizers on the performance of the DSSCs were investigated, the study reveals that all the cells possess comparable values of V of about 0.55 0.1 V. However, of the two lone sensitisers,oc betalain based device gave a better efficiency of 0.21% while anthocynin based device achieved 0.17 %, this is attributed to their different anchoring functional groups. The, combined anthocyanin and betalain dyes (water extract) had the highest conversion efficiency of 0.26 % suggesting dye synergic absorption effect as a result of co-sensitisation, the lower efficiency of 0.24 %) achieved by combined anthocyanin and betalain (ethanol extract) is attributed to the contributory effect of the extraction solvents
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    Diurnal and annual cycles of surface refractivity and related parameters in Minna, Central Nigeria
    (The Nigerian Journal of Space Research, 2011) O. D. Oyedum, J. A. Ezenwora, K. C. Igwe, J. O. Eichie and A. S. Moses
    Radio refractivity N exerts considerable influence on radio signals at VHF and higher frequency bands. In particular, surface refractivity correlates positively with radio field strengths, and knowledge of its temporal variability is important in predicting performance of terrestrial radio networks, especially at VHF and microwave frequencies. Knowledge of the variability of the atmospheric parameters from which N derives is also important for radio propagation and other applications such as Agriculture and Tourism. Measurement of atmospheric parameters is also necessary to update past records, especially in the light of climate change. Surface refractivity values derived from values of air pressure P, temperature T and relative humidity H measured for two consecutive years (2008-2009) in Minna (09037N, 06032E),Central Nigeria are statistically analysed to explore their diurnal and seasonal cycles, as well as their inter-relationships. The results reveal that surface refractivity and the related weather variables show clear diurnal and seasonal trends with discernible relationships. In particular, diurnal N values have high correlation with diurnal P values, while monthly averages of N and H are also highly correlated; and the hot weather generally experienced in the month of April in Minna may be attributed to a combination of high humidity and high temperature at surface level.
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    Assessment of shielding potentials and radiological safety indices of Nigerian granite rocks.
    (NJTR FUTMINNA, 2019) OLARINOYE, OYELEKE; ALABI AA; SURAJ K
    The activity concentration of primordial radioisotopes (238U, 232Th and 40K) in granite rock samples from Minna, North central Nigeria were measured using a sensitive HPGe detector for gamma spectrometric measurement. Five granite rock samples were collected from Maikunkele, Bosso, Maitumbi, Chanchaga and Paiko areas of the town. The average activity concentrations for the radionuclides in the rocks were: 27 ± 4 Bq/kg; 48 ± 7 Bq/kg and 874 ± 86 Bq/kg for 238U, 232Th and 40K respectively. The average absorbed dose rate, effective dose; radium equivalent (Req) and internal hazard index (Hin) were 65 ± 10 nG/h; 0.32 ± 0.05 mSv/y; 140 ± 21 Bq/kg and 0.45 ± 0.07 respectively. All the rock samples had Req less than the recommended safety value of 370 Bq/kg. All evaluated radiological safety indices fell within the recommended safety limits and world average values. The analysis of radionuclide content of the granite rocks showed that they do not pose environmental radiation risk to humans when used as structural shielding materials. Mass attenuation coefficients of the granite samples evaluated via the WinXcom computer code suggested that the granite rocks considered have good shielding capacity comparable to that of ordinary concrete.
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    EXABCal: A program for calculating photon exposure and energy absorption buildup factors
    (ELSEVIER, 2019) OLARINOYE, OYELEKE; ODIAGA RAMOND; SILAS PAUL
    This research presents a new Windows compatible program (EXABCal) for photon exposure and energy absorp tion buildup factors for standard energy grid from 0.015- 15 MeV for elements, mixtures and compound. This program was written using Python programming language and the calculation of buildup factors was based on the well-known Geometric Progression (GP) fitting procedure. The equivalent atomic numbers and GP fitting pa rameters of mixtures and compounds can also be evaluated using this program. The program has been used to evaluate the photon exposure and energy absorption buildup factors for standard energy grid from 0.015- 15 MeV for water, air and concrete, compared with values from the American Nuclear Society (ANS) standard reference data (ANSI-6.4.3) and found to be of high accurate with minimal errors. The program is fast and easy to use and will be of valuable interest to medical Physicist, radiation Physicists, Radiation shielding design engineers, stu dents, teachers and researchers and other experts working in areas where nuclear radiation is applied.
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    Photon Absorption Buildup Factors for Different Concrete Types.
    (2019) OLARINOYE, OYELEKE; MOHAMMED BELLO
    Concrete is one of the most widely used materials for structural radiation shielding application. However, the shielding capacity of a concrete has been argued to depend largely on its constituent materials and sometimes its mass density. Hence concretes with different composite materials are expected to perform differently when used for shielding purpose. This research reports the estimation of the equivalent atomic numbers and photon Energy Absorption Buildup Factors (EABF) for eleven different species of concrete. The relationship between equivalent atomic number, density and EABF was also investigated. The concretes considered were categorized into light and heavy concretes based on their mass density. The EABF were calculated using the well-known geometric progression fitting procedure for photon energies from 0.015 MeV to 15 MeV and for penetration depth up to 40 mfp. An appreciable variation in the EABF was observed at different depth, energy and for each concrete type. The EABF were found to be high in the low and high energy regions and maximum in the intermediate energy section. The variation of EABF with energy and depth was attributed to the photoelectric, Compton scattering and pair production interaction modes. Although most high density concretes show lower buildup factor irrespective of depth and energy, an indication of good photon shielding coefficient. However, based on this study, it is the equivalent atomic number that can be best used to accurately compare the buildup factors amongst concrete rather than density.
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    Comparative assessment of natural radionuclide content of cement brands used within Nigeria and some countries in the world
    (ELSEVIER, 2014) E.O. Agbalagba; R.O.A. Osakwe; OLARINOYE, OYELEKE
    The gamma spectrometric analysis of different brands of cement used as building and construction material in Nigeria has been carried out in this study. Samples of 12 brands of gray Ordinary Portland Cement (OPC) and 5 brands of white cement of six samples each were collected and analyzed for their radiological content using gamma spectrometry method. The average value of 226Ra, 232Th, and 40K for OPC is 30.2 ± 10.4 Bq kg−1, 24.6 ± 7.1 Bq kg−1, and 251.3 ± 27.6 Bq kg−1 respectively and the average value for the white cement is 41.9 ± 16.7 Bq kg−1, 30.1 ± 9.4 Bq kg−1 and 340.2 ± 37.7 Bq kg−1 respectively. The total average content of 226Ra, 232Th, and 40K for all the cement brand samples are 36.1 ± 13.6 Bq kg−1, 27.4 ± 8.3 Bq kg−1, and 295.8 ± 32.7 Bq kg−1 respectively. These values obtained are lower when compared to the world average values(226Ra-50 Bq kg−1,232Th-50 Bq kg−1and40K-500 Bq kg−1)forbuildingmaterials.Theestimatedradium equivalent activities (Raeq), representative index (Iγ), average absorbed γ-dose rate (D), the annual effective dose rate (AEDE), annual gonadal dose equivalent (AGDE) external and internal hazard indices and the Excess life cancerrisk (ELCR)werelowerthantherecommendedsafelimitandarecomparablewithresultsfromsimilar studies conducted in othercountries. The evaluated mean gonadal dose equivalents of three cement brandsam ples were found to be higher than the world average for building material while others are less than the world average. A comparison of the average activity values obtained in Nigeria cement and other countries of the world show that those countries with history of high radionuclide solid minerals have activity concentration far above that of Nigerian cement, while these values agreed with those obtained in other countries.
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    ASSESSMENT OF NATURAL RADIOACTIVITY LEVELS AND RADIATION HAZARDS IN THE TERTIARY INSTITUTIONS IN MINNA, NIGER STATE, NIGERIA.
    (2012-01-15) Kolo, M. T.,; Baba-Kutigi, A. N.,; OLARINOYE, OYELEKE; Sharifat, I.
    Activity concentrations of natural radionuclides in 30 surface soil samples collected across the three campuses of the two tertiary institutions in Minna, Niger State, Nigeria, were studied and evaluated. This survey was carried out using gamma spectrometric technique which employs NaI(Tl) gamma detector at the Center for Energy Research and Training (CERT), Ahmadu Bello University, Zaria, Nigeria. The mean values for the activity of 226Ra, 232Th and 40K were found to be 7.8±1.3Bqkg-1, 29.4±0.9Bqkg-1 and 229.4±1.8Bqkg-1 respectively. The activity profile of the primordial radionuclides in the soil samples investigated showed the existence of low level activity across the three campuses. The mean value of the annual effective dose equivalent obtained from this study is 0.04mSvyr-1, with mean external hazard index of 0.2. These average values fall within the internationally provided safety range for outdoor radiation exposure. The values obtained from this investigation for all the radiation parameters for the studied soil samples showed that none of the campuses investigated pose any significant radiological threat to the public.
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    NATURAL RADIOACTIVITY IN BOREHOLE WATER OF SOME WARDS IN MINNA, NIGER STATE
    (2011-01-11) Kolo, M. T.,; Baba-Kutigi A. N.,; OLARINOYE, OYELEKE; Ibrahim. S.
    28 samples o~ borehole water used for drinking and domestic purposes were sampled from three wards namely Bosso ward (A), Matkunkele ward (B), and Maitumbi ward (C) in Minna city, Niger State. The water samples were analyzed at the Center for Energy Research and Training, CERT, Ahmadu Beilo University Zaria, for their natural radioactivity content, using the Eurisis system-eight-:-channel-gas-filled proportional counter. The results obtained show that none of the samples from the three wards has gross alpha activity higher than the recommended guidelines by World Health Organization (WHO). The beta activity of two samples from ward B and four from ward C, however, shows a little elevation above the recommended screening level for potable water. The elevations notwithstanding, however, the overall results generally show that water from boreholes in the three wards is safe for drinking and other domestic purposes.
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    Variation of Effective Atomic Numbers of some Thermoluminescence and Phantom Materials with Photon Energies
    (2011-05-15) OLARINOYE, OYELEKE
    Effective atomic numbers (Zeff) of 15 materials (CaSO4, nylon, methyl but-3-enoate, mylar, C2F4, Al2O3, SiO2, stearate, CH4, CaF2, water, Iron sulphate, polystyrene, polyvinyl, and potassium calcium sulphate) used in dosimetry and substitute materials were calculated using standard formula based on their mass attenuation coefficients (µm). The µm of the materials were obtained for photon energies of 0.01 KeV to 20 MeV using WinXCOM. Generally, Zeff for each of the substances considered is not a constant but varies with photon energy. Zeff varies from11-17 for CaSO4, 3-6 for nylon, 6-7 for methyl but-3-enoate, 4-7 for mylar, 8-9 for C2F4, 10-12 for Al2O3, 10-12 for SiO2, 3-6 for stearate, 2-5 for CH4, 13-18 for CaF2, 3-8 for water, 12-23 for Iron sulphate, 4-6 for polystyrene, 5-16 for polyvinyl, and 1217 for potassium calcium sulphate. The variations of Zeff with photon energy for all the 15 substances follow similar pattern. The variations were dictated by photon interaction processes. The highest value of Zeff for all the materials was obtained at the lowest energy, while the lowest value was obtained between 0.1 and 1.5 MeV. The mean atomic number of each compound was also found to be equal to the Zeff obtained at intermediate energies of the energy spectrum considered (0.1 MeV -1.5 MeV). The upper and lower limit of Zeff for each of the considered materials was found to be dictated by the atomic numbers of the constituent elements of the materials