Natural radionuclides

Oguta LGA is surrounded by 44 oil wells located around different communities. Preliminary investigations indicated that crude wastes were not properly managed and oil spillage occurred regularly in the LGA. Therefore, assessment of both radionuclide contents in yam matrix and health risks in Oguta was carried out to determine possible radiological health risks associated with improper management of crude wastes, and also evaluate haematological health profile in the LGA for future reference and research. A well calibrated NaI (Tl) detector was deployed for the radiological investigation, and about 5 ml of blood samples were collected from 190 participants each from Oguta and the control LGAs for haematological assessment. Mean activity concentrations due to 40K, 226Ra and 232Th in yam samples from Oguta LGA were 189.99 ± 59.14 Bqkg-1, 23.75 ± 5.69 Bqkg-1 and 30.99 ± 9.51 Bqkg-1, respectively while mean activity concentrations due to natural radionuclides in yam samples from control LGA were 110.40 ± 78.53 Bqkg-1, 10.12 ± 3.34 Bqkg-1 and 18.39 ± 8.74 Bqkg-1 for 40K, 226Ra and 232Th, respectively. Committed effective dose equivalent values in Oguta and the control LGAs were 704.95 ± 183.30 μSvy-1 and 403.65 ± 172.19 μSvy-1, respectively which are less than world average value of 1.1 mSvy-1. Crucially, one-way ANOVA at α0.05 has indicated that effects of radiological parameters due to natural radionuclides in yam from Oguta are significantly different from effects of radiological parameters due to natural radionuclides in yam from the control LGA. However, the percentage contributions of natural radiation exposures to incidence of cancer in Oguta and the control LGAs are just 1.7% and 1.4%, respectively, and haematological investigations have shown that overall health of the communities in the study LGAs has not been compromised due to environmental and human factors. Hence, natural radioactivity may have been elevated in Oguta but the concentration levels are not yet alarming. Radiological health risks could result from consistent exposure to those natural radionuclides in the long term.

The article describes the necessary conditions for the phenomenon of thermal energy release in a magnetic fluid placed in a high-frequency rotating magnetic field. The minimum amplitude of the magnetic field was calculated and the thermal power released (by the rotating spherical nanoparticles in the viscous medium) was estimated. The estimations were based on the assumption that the magnetic relaxation times (τN and τB) and the magnetic field rotation period (τrot) meet the condition: τN>>τrot>>τB. The principle of operation and construction of the device generating a high-frequency rotating magnetic field is described. Preliminary experimental studies were carried out using a magnetic fluid with magnetite nanoparticles that indicated magnetic relaxation as the cause of the released heat. The value of the absorption rate in the experiment and its dependence on the strength of the magnetic field were determined.