Background: Measurement of the radia on dose distribu on is important in assessing the health risk a popula on and serve as reference in documen ng changes to environmental radioac vity in soil due to man-made ac vi es. Materials and Methods: The ac vity concentra on of 238 U, 232 Th and 40 K in soil samples obtained from different loca ons in Ajaokuta Local Government area was measured using Hyper Pure germanium Detec on System (HPGe). Results: The calculated average concentra on of the radionuclides ranged from 12 ± 1 Bqkg-1 to 59 ± 2 Bqkg-1 for 238 U, 14 ± 1 Bqkg-1 to 78 ± 5 Bqkg-1 for 232 Th and 49 ± 2 Bqkg-1 to 1272 ± 23 Bqkg-1 for 40 K. In order to evaluate the radiological hazards due to natural radionuclides within Ajaokuta, the absorbed dose rate, gamma index, radium equivalent and excess life me cancer risk were es mated. According to measured data from the top soil (0-10 cm), the es mated radium equivalent (Ra eq) ranges from 55.7 Bqkg-1 at Steel Complex to 253.3 Bqkg-1 obtained from Forest samples. Conclusion: The mean absorbed dose rate, annual effec ve dose and gamma radia on index evaluated were 66.2 nGyh-1 , 81.2 µSvy-1 and 1.05 respec vely which are higher than the recommended limit for normal background radia on. Thus, we conclude that people living in these loca ons may be exposed to higher radia on.

No abstract

A theoretical study of the donor-related absorption coefficient in spherical CdS quantum dots (QD) in the presence of a uniform magnetic field is performed. The wave functions and the eigenvalues of the initial and final states are obtained in the effective-mass approximation by using a variational method and a perturbation method, respectively. The results obtained show that the absorption coefficient presents essentially two peaks; one associated with on-center donors and another related to transitions involving donors at the QD edge. The dependences of the absorption coefficient on sample dimensions, the magnetic field strength and the light polarization are discussed.

Dye-sensitised solar cells (DSSCs) are 3rd generation photovoltaic device that imitate photosynthesis in plants. The fundamental concept of a DSSCs is that the photoanode is covered by the dye as a sensitiser. Natural dyes from plant-based extracts have gained attention as alternatives to toxic and expensive commercial dye sensitisers. Various studies have been conducted on the use of natural plant dye extracts for DSSCs . However, more fundamental studies on their adsorption on TiO2 photoanode nanoparticles are still not well understood. In this study, we investigated the crystal structure, optical absorption, and photoluminescence properties of TiO2, Cucurbita maxima, and Cucurbita maxima dyes adsorbed on TiO2 nanoparticles as potential materials for DSSCs. Raman spectra confirmed the anatase phase of the TiO2 nanoparticles. The particle size of 12 ± 2 nm was confirmed through the transmission electron microscope. The optical absorption properties of Cucurbita maxima show two distinct absorption bands: blue visible (450–500 nm) and red visible (635–674 nm). The photoluminescence spectra of the dye extract and its adsorption onto the TiO2 nanoparticles showed two prominent peaks in the blue and red regions of the electromagnetic spectrum. No significant peak is observed in the green region of the electromagnetic spectrum. These studies shed more light on the fundamental properties of chlorophyll adsorption on TiO2 nanoparticles and their optical and photoluminescence properties for applications as sensitisers in DSSCs.