Surface radio refractive gradient and k-factor are very imperative in observing propagation conditions, designing and planning of microwave communication links in the lower part of the atmospheric boundary layer. The measurement of weather variables (air temperature, atmospheric pressure, relative humidity and wind speed) were conducted in this study at the School of Science, Emmanuel Alayande College of Education, Oyo (7.83°N, 3.95°E), Oyo State, Nigeria. The research was carried out for a period of one year (January to December, 2020) using self-designed cost effective portable weather monitoring systems. The systems were sited from the ground to a height of 200 m on a 220 m Nigeria Television Authority (NTA) UHF channel 37 tower at Oke-Apitipiti in Oyo Town of Oyo State. The calculated daily and monthly averages data are employed to investigate the vertical surface radio refractivity and its refractivity gradient. The highest value of -1.093E+26 N-units/km was recorded in January, while the month of July experienced the least of about -9.305E+19 N-units/km. The months of January–July verified sub-refractive conditions with propagation conditions having varying degree of occurrence. On the other hand, super-refraction and ducting were recorded mostly between August–December from the study. The results also find applicability in radio engineering for refining VHF/UHF terrestrial links based on clear-air considerations which will support operational planning of terrestrial radio networks in Oyo, South Western Nigeria Keywords: Microwave; k-factor; refractivity gradient; sub-refractive; super-refraction

This study aims to investigate the influence of SILAR cycle on the energy bandgap of Iron Copper Sulphide (FeCuS) thin films deposited on soda-lime glass substrate (SLG). A Successive Ionic Layer Adsorption and Reaction (SILAR) method is one of the chemical methods for making uniform and large area thin films, which is based on immersion of substrates into separately placed cationic and anionic precursors. The technological importance of chemically deposited iron copper sulphide (FeCuS) using SILAR technique vis-à-vis the effect of SILAR cycle on the energy band gap of the deposited thin films has not been unraveled. Thin films of Iron Copper Sulphide were grown on soda-lime glass substrate (SLG) by a simple solution based Successive Ionic Layer Adsorption and Reaction (SILAR) technique at room temperature (300 K) with EDTA, TEA and NH 4 OH as complexing agents at different SILAR cycles (20, 30 and 40 cycles) of deposition. The thin films grown were characterized using Avantes UV-VIS spectrophotometer (Avalight-DH-S-BAL) in the wavelength range 200-1000nm and Four Point Probe machine (Keithley 4ZA4 2400 Sourcemeter, manufactured by Tektronix Company). The optical properties considered revealed high absorbance and reflectance but low transmittance in the UV region; low values of absorbance and reflectance accompanied with high transmittance in the VIS region. Moreover, the resistivity of the grown thin film varied from 9.480 x 10 6 Ωm to 4.366 x 10 7 Ωm in order of increasing SILAR cycle, direct band gap of 3.76e V, 3.51e V and 3.42e V were obtained. These properties suggest that the films are suitable for solar cell and optoelectronic applications.

This study reported the investigation of the Radio Frequency (RF) signal propagation of Global System for Mobile Communications (GSM) coverage in Emmanuel Alayande College of Education (EACOED), Oyo, Oyo State, Nigeria. The study aims at amplifying the quality of service and augment end users' sensitivity of the wireless services operation. The drive test method is adopted with estimation of coverage level and received signal strength. The Network Cell Info Lite application installed in three INFINIX GSM mobile phones was employed to take the measurement of the signal strength received from the transmitting stations of different mobile networks. The results of the study revealed that MTN has the maximum signal strength with a mean value of - 68.33 dBm, directly followed by Globacom (-80.41 dBm) and Airtel with -83.13 dBm. The Airtel signal has a conspicuously invariable poor performance with coverage level of 41.66 %. Conversely, the MTN and Globacom signal reception are observed to surpass the Airtel network within the college premises with 83.33 % and 60.41 % coverage level respectively. This implies that the signal quality for MTN and Globacom networks were comparatively disseminated within the college with inconsequential fluctuations in quality while Airtel signal is subsided and weaken. The poor performance in some areas was due to the presence of physical impediments and far distances location of base station antennas in the promulgation locations. This study therefore suggested that Airtel and Globacom Base Transceiver Stations (BTS) should be positioned within the college to improve good network reportage level.

Natural radionuclides such as 40K, 226Ra and 228Ra are found naturally in water and sediments of rivers, likewise in soils. They are transferred to aquatic animals through ingestion. Radioactivity concentrations and dose rates of 40K, 226Ra and 228Ra in crayfish species from Ode Omi River in coastal region, Ogun State Southwest of Nigeria were determined by gamma spectrometry using NaI (TI) detector coupled with a pre-amplifier base to a multiple channel analyzer (MCA). 15 samples of crayfish were collected. Cherax tenuimanus had the highest mean concentration and dose rate of values 106.87 ± 9.11 Bq kg–1 and 0.00960 mGy hr–1 respectively for 40K. Moreso, for 226Ra, Cherax quadricarinatus had the highest mean concentration and dose rate of values 2.57 ± 0.82 Bq kg–1 and 4.50 x 10–7 mGy hr–1 respectively. Concerning228Ra, Astacopsis gouldi had the highest mean concentration and dose rate of values 5.23 ± 0.46 Bq kg–1 and 5.86 x 10–13 mGy hr–1, respectively. The average dose rate of the radionuclides in all the crayfish was calculated to be 4.62 x 10 ̶ 3 mGy hr–1 which was below the 0.4 mGy hr–1 limit recommended. The average annual committed effective dose and average excess lifetime cancer risk of all the radionuclides to the consumers were 0.0807 mSv yr–1 and 0.589 x 10–4, respectively, which were below global limits of 1.0 mSv yr–1 and 0.29 x 10–3, respectively, therefore, the ingestion of these natural radionuclides could not pose any radiological health hazards to the aquatic animals, likewise man the consumers. Keywords: Radionuclide concentration, Dose rate, Cancer Risk.

No abstract