Health and ecological hazards due to natural radioactivity in soil from mining areas of Nasarawa State,Nigeria

Nasarawa State is located in north central Nigeria and it is known as Nigeria's home of solid minerals. It is endowed with barite, copper, zinc, tantalite and granite. Continuous releases of mining waste and tailings into the biosphere may result in a build-up of radionuclides in air, water and soil. This work therefore aims to measure the activity concentration levels of primordial radionuclides in the soil/sediment samples collected from selected mines of the mining areas of Nasarawa State. The paper also assesses the radiological and radio ecological impacts of mining activities on the residents of mining areas and their environment. The activity concentrations of primordial radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) in the surface soils/sediment samples were determined using sodium iodide-thallium gamma spectroscopy. Seven major mines were considered with 21 samples taken from each of the mines for radiochemistry analysis. The human health hazard assessment was conducted using regulatory methodologies set by the United Nations Scientific Committee on the Effects of Atomic Radiation, while the radio ecological impact assessment was conducted using the ERICA tool v. 1.2. The result shows that the activity concentrations of ⁴⁰K in the water ways of the Akiri copper and the Azara barite mines are 60 and 67?% higher than the world average value for ⁴⁰K, respectively. In all mines, the annual effective dose rates (mSv y^?1) were less than unity, and a maximum annual gonadal dose of 0.58 mSv y^?1 is received at the Akiri copper mine, which is almost twice the world average value for gonadal dose. The external hazard indices for all the mines were less than unity. Our results also show that mollusc-gastropod, insect larvae, mollusc-bivalve and zooplankton are the freshwater biotas with the highest dose rates ranging from 5 to 7 µGy h^?1. These higher dose rates could be associated with zinc and copper mining at Abuni and Akiri, respectively. The most exposed terrestrial reference organisms are lichen and bryophytes. In all cases, the radio ecological risks are not likely to be discernible. This paper presents a pioneer data for ecological risk from ionizing contaminants due to mining activity in Nasarawa State, Nigeria. Its methodology could be adopted for future work on radioecology of mining.     

Assessment of health hazard due to natural radioactivity in Kluang District,Johor, Malaysia

The radiation survey of the ambient environment was conducted using two gamma detectors, and the measurement results were used in the computation of the mean external radiation dose rate, mean-weighted dose rate and annual effective dose, which are 144 nGy h^?1, 0.891 mSv y^?1 and 178 μSv, respectively. A high-purity germanium detector was used to determine the activity concentrations of ²³²Th, ²²⁶Ra and ⁴⁰K in soil samples. The results of the gamma spectrometry of the soil samples show radioactivity concentration ranges from 19±1 to 405±13 Bq kg^?1 with a mean value of 137±5 Bq kg^?1 for ²³²Th, from 21±2 to 268±9 Bq kg^?1with a mean value of 78±3 Bq kg^?1 for ²²⁶Ra and from 23±9 to 1268±58 Bq kg^?1 with a mean value of 207±13 Bq kg^?1 for ⁴⁰K. Radium equivalent activity (Ra_eq) and external hazard index (H_ex) were 290 Bq kg^?1 and 0.784, respectively, which were safe for the population. The mean lifetime dose and lifetime cancer risk for each person living in the area with average lifetime (70 y) were 12.46 mSv and 7.25×10^?4 Sv year, respectively. The results were compared with values given in United Nations Scientific Committee on the Effects of Atomic Radiation 2000.     

Best proximity point theorems: resolution of an important non-linear programming problem

The purpose of this article is to resolve the non-linear programming problem of globally minimizing the real valued function ${x \longrightarrow d(x, Sx)}$ where S is a non-self-mapping in the setting of a metric space with the distance function ‘d’. An iterative algorithm is also furnished to find a solution of such global optimization problems. As a consequence, one can determine an optimal approximate solution to some equations of the form Sx = x.     

Plaquette percolation on frustrated lattices in two dimensions

We study the ±J quenched-random-bond Ising model in two dimensions. Critical concentrations for percolation of frustrated and normal plaquettes are calculated for the triangular and square lattices by computer simulation. Connection with T = 0 statistical properties is discussed.     

Travelling waves in an open cubic autocatalytic system

A continuous-flow, unstirred reactor (CFUR) is considered in which the reaction is purely cubic autocatalysis and in which the exchange of reactants between the reactor and its reservoir is modelled by linear diffusive interchange terms. The system is capable of supporting two, stable, spatially uniform stationary states. The possibilities of initiating travelling waves of permanent form (front waves), in which the concentrations vary monotonically between these two stationary states is, investigated. It is seen that the formation of front waves requires the dimensionless parameter D _A /D _B (D _A ,D _B being the diffusion coefficients of reactant and autocatalyst, respectively) to be such that 4, a result confirmed by numerical integrations of an initial-value problem. For values of larger than this, permanent-form waves are not initiated with a more complex structure evolving in the initial-value problem. Here the forward-propagating front leaves behind a region in which oscillations in the concentrations of both species are observed. These individual oscillations are spatially fixed with the region where this oscillatory response is observed propagating backwards into the region of spatially uniform concentration.     

Numerical investigation on bioconvection flow of Oldroyd-B nanofluid with nonlinear thermal radiation and motile microorganisms over rotating disk

Journal of Thermal Analysis and Calorimetry - In this paper, the mechanism of radiative Oldroyd-B nanofluid flow over a rotating disk with activation energy and motile microorganisms is examined....     

Heat transfer analysis of tangent hyperbolic nanofluid in a ciliated tube with entropy generation

In this paper, we analyze the effect of heat transfer on the flow of tangent hyperbolic nanofluid in a ciliated tube (fallopian tube where embryo in blood make the development). This study will be beneficial for the researchers and medical experts in the field of embryology. The nanoparticles are beneficial to remove the cysts from the fallopian tube where development of embryo takes place. To resolves the ciliary flow problems, medical doctors use nanoparticles (drug delivery) that may create a temperature gradient. The heat transfer helps to optimize the energy for which the entropy generation is reduced. Therefore, in this research we discuss the heat transfer effect on tangent hyperbolic nanofluid and entropy generation due to ciliary movement. The governing partial differential equations are solved by HPM and software MATHEMATICA?. Effect of viscoelastic parameter, nanoparticles, cilia length and Brinkman number on the velocity, temperature and entropy generation has been illustrated with the help of graphs. Graphical results show that thermal conductivity of fluid increases by adding nanoparticles. The entropy generation due to nanoparticles will decrease the viscosity near the tube wall and blood through tube will flow with normal pressure.

     

Synthesis,spectroscopic exploration,biocidal activities,and crystal structures of 3‐(3‐fluorophenyl)‐2‐phenylpropenoic acid and trimethyltin(IV) complex

The ligand, 3‐(3‐fluorophenyl)‐2‐phenylpropenoic acid, [C₁₅H₁₁FO₂] ( I ) was prepared by reacting equimolar amount of phenyl acetic acid with 3‐fluorobenzaldehyde (1:1) using Perkin condensation method. The trimethyltin(IV) carboxylate, [Me₃SnO₂FH₁₀C₁₅] ( II ) was synthesized by refluxing an equimolar (1:1) mixture of trimethyltin chloride and silver salt of the ligand acid, [C₁₅H₁₀FO₂Ag] ( Ia ). The ligand and complex both were characterized by elemental analysis, IR, mass, ¹H NMR, and X‐ray crystallographic data. On the basis of ¹H NMR data, (²J[^117/119Sn, ¹H] and C Sn C bond angle), it is concluded that the environment around the tin atom in solution is tetrahedral. The Infrared spectroscopic results showed that trimethyltin(IV) derivative has 5‐coordinated polymeric structure with bridging carboxylate groups in the solid state, which has been confirmed by the X‐ray crystallographic data. The crystal of ligand acid ( I ) is triclinic with space group Pbar1. However, the crystal of the complex ( II ) is monoclinic with space group C_2/c. The geometry around the tin atom is distorted trigonal bipyramid with O(1) and O(2) atoms in apical positions. The ligand ( I ) and complex ( II ) were also tested for their biocidal activities. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:398–406, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20032     

Heat transfer of a nanoliquid thin film over a stretching sheet with surface temperature and internal heat generation

Journal of Thermal Analysis and Calorimetry - In this paper, the heat transfer in thin film flow on unsteady stretch plate of nanofluids is studied. The nanoparticles of copper Cu, alumina Al2O3...     

Role of hybrid nanoparticles in thermal performance of peristaltic flow of Eyring–Powell fluid model

Journal of Thermal Analysis and Calorimetry - Nanoparticles have great potential to improve thermophysical properties and thermal execution. At different polymer fixations, hybridization of...