Assessment of Activity Concentration of Radionuclides in Soil and Cassava Food Crop from Solid Mineral Mining Site in Ishiagu, Ivo L.G.A of Ebonyi State, Nigeria

The assessment of activity of concentration of radionuclides in soil and food crops from solid mineral mining sites at Ishiagu, in Ivo L.G.A of Ebonyi State was carried out using the necessary measuring instruments. Samples of soil and cassava crop collected from around the mining sites. The samples were analysed using gamma ray spectrometry. The average activity concentration of 226Ra, 232Th and 40K in soil samples were 12.37,16.08, and 144.29 Bqkg-1 while those for cassava were 2.81, 16.80, and 205.41 Bqkg-1. The soil/plant radionuclide transfer ratio estimated are 0.62, 2.43 and 2.51 for 226Ra, 232Th and 40K, respectively. All the radiological risk parameters estimated are relatively low. The result of this work showed that the obtained results for all samples were lower than the international accepted limit. Hence, from radiological health standpoint, the obtained values of effective doses may not pose significant threat to both human and the environment.

Theoretical Study of Solvent Effects on the Electronic and Thermodynamic Properties of Tetrathiafulvalene (TTF) Molecule Based on DFT

Tetrathiafulvalene () is an organosulfur compound used in the production of molecular devices such as switches, sensors, nonlinear optical devices and rectifiers. In this work, a theoretical study on the effects of solvent on TTF molecule was investigated and reported based on Density Functional Theory (DFT) as implemented in Gaussian 03 package using B3LYP/6-31++G(d,p) basis set. Different solvents were introduced as a bridge to investigate their effects on the electronic structure. The HUMO, LUMO, energy gap, global chemical index, thermodynamic properties, NLO and DOS analysis of the TTF molecule in order to determine the reactivity and stability of the molecule were obtained. The results obtained showed that the solvents have effects on the electronic and non-linear-optical properties of the molecule. The optimized bond length revealed that the molecule has strong bond in gas phase with smallest bond length of about 1.0834Å than in the rest of the solvents. It was observed that the molecule is more stable in acetonitrile with HOMO-LUMO gap and chemical hardness of 3.6373eV and 1.8187eV respectively. This indicates that the energy gap and chemical hardness of TTF molecule increases with the increase in polarity and dielectric constant of the solvents. The computed results agreed with the results in the literature. The thermodynamics and NLO properties calculation also indicated that TTF molecule has highest value of specific heat capacity (Cv), total dipole moment () and first order hyperpolarizability () in acetonitrile, while acetone has the highest value of entropy and toluene has a slightly higher value of zero point vibrational energy (ZPVE) than the rest of the solvents. The results show that careful selection of the solvents and basis sets can tune the frontier molecular orbital energy gap of the molecule and can be used for molecular device applications.

Assessment of Outdoor Gamma Exposure Level of Some Swampy Agricultural Soils of Nasarawa West, Nigeria

In this study, assessment of outdoor background exposure levels in some selected swampy agricultural soil in Nasarawa West, Nigeria has been conducted. An in-situ measurement of outdoor background exposure rate (in mRhr-1) for a total of fifty farms (ten each from Keffi (KF), Kokona (KK), Karu (KR), Toto (TT), and Nasarawa (NS)) were done using a well calibrated portable halogen-quenched Geiger Muller (GM) detector (Inspector alert Nuclear radiation monitor SN:3544). A geographical positioning system (GPS) was used at an elevation of 1.0 m above ground level to obtain the geographical location. The radiological hazard parameters were evaluated using the measured outdoor background exposure rates. The values obtained were compared with recommended permissible limits to ascertain the radiological hazard status of the swampy agricultural farms. The mean values of the outdoor background exposure levels (0.23, 0.038, 0.028, 0.022, and 0.039 mRh-1), absorbed dose rates (458.49, 334.95, 188.79, 194.01, and 343.65 nGyh-1) and excess lifetime cancer risk (1.968, 1438, 0.810, 0.832, and 1.475) each for KF, KK, KR, TT, and NS respectively, are higher than the recommended safe limits of 0.013 mRh-1, 84.0 nGyh-1, 0.00029 respectively as recommended by UNSCEAR and ICRP. On the other hand, the mean annual effective dose equivalent (AEDE) values (0.563, 0.410, 0.232, 0.238, and 0.421 mSvy-1 for KF, KK, KR, TT, and NS respectively) are below the recommended permissible limits of 1.00 mSvy-1 for general public exposure. Generally, the study revealed that swampy agricultural soils in Nasarawa west are radiologically safe with little contamination which could be attributed to the geological formation and partly due to human activity in the area.

Holographic Dark Energy and Dark Matter Interaction in Anisotropic Bianchi Type-V Universe

In this study, we consider an holographic dark energy and dark matter interacting model in the Bianchi Type-V universe with a stretched exponential scale factor. We obtain the Hubble, shear, deceleration, and equation of state parameters based on the presented model and give the numerical solutions. We show that the anisotropy in the early universe plays an important role in the time evolution of the universe. Furthermore, we show that an interacting anisotropic model with stretched exponential scale factors can explain all epochs of the universe.

Estimation and Investigation of Mean and Most Probable Velocities of Tropospheric Gases over Ilorin, Nigeria

In this study, the monthly average minimum and maximum temperature meteorological data obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF) during the period of thirty eight years (1979 – 2016) were used to estimate the mean velocity and most probable velocity of atomic Oxygen and Hydrogen for Ilorin. The values of the mean velocity and most probable velocity for these atoms were compared to the value of escape velocity. The results revealed that the highest values of mean velocity and most probable velocity for atomic Oxygen were found to be in the month of March with and respectively and the highest values of mean velocity and most probable velocity for atomic Hydrogen were found to be in the month of March with and respectively. Based on the values of the mean velocity and most probable velocity for atomic Oxygen and Hydrogen obtained during the studied period suggests that these atoms cannot escape the gravitational field as their values are less than the escape velocity .

Numerical Simulation of One Step Block Method for Treatment of Second Order Forced Motions in Mass-Spring Systems

This paper discuss the numerical simulation of one step block method for treatment of second order forced motions in mass-spring systems of initial value problems. The one step block method has been developed with the introduction of off-mesh point at both grid and off- grid points using interpolation and collocation procedure to increase computational burden which may jeopardize the accuracy of the method in terms of error. The basic properties of the one step block method was established and numerical analysis shown that the one step block method was found to be consistent, convergent and zero-stable. The one step block method was simulated on three highly stiff mathematical problems to validate the accuracy of the block method without reduction, and obviously the results shown are more accurate over the existing method in literature.

Numerical Study of Transparent Conductive Oxide (TCO) Layer on the Performance of Methyl-Ammonium Tin Iodide (CH3NH3SnI3) Perovskite Solar Cells Using SCAPS

Substrates used in perovskite solar cells as front contact are usually transparent conductive oxide (TCO) to allow light to pass through the device. The dominating TCO employed in perovskite solar cells are indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO). However, it is imperative to investigate alternative TCOs due to the scarcity of indium metal, relatively low electrical conductivity and high leakage current in ITO and FTO. In this study, simulation has been carried out using Solar Capacitance Simulator (SCAPS) to investigate the efficiency of methyl-ammonium tin iodide (CH3NH3SnI3) based solar cells including various TCOs such as boron-doped zinc oxide (BZO), molybdenum trioxide (MoO3) and zinc oxide (ZnO). TCO parameters such as thickness, donor concentration and operating temperature were varied to study their influence on device performance. The best device performance was achieved using MoO3 with power conversion efficiency of 25.83 % and Jsc, Voc and FF of 32.44 mA/cm2, 0.979 V and 81.38 % respectively. The work shows the potential of fabricating an improved CH3NH3SnI3 perovskite solar cell with MoO3 as front contact.

Design Analysis and Implementation of Automatic Fire Extinguishing System Using ATmega16 Microcontroller as Control

Aim: The aim of this research is to design an automatic fire detection and control. Methodology: The system consists of two sensors, microcontroller, buzzer and a pump/sprinkler. An LM35 integrated chip has been used as temperature sensor while MQ-2 gas sensor has been used as smoke sensor. All sensors are connected to the microcontroller through an input/output port. The controlling software for the whole system was designed in C programming language. The popular high performance, low power 8-bit microcontroller from the AVR family microcontrollers has been used. The system was finally tested by introducing fire parameters (smoke and temperature) close to the smoke and temperature detectors respectively. When the parameters go above the set level in the detectors, audio alarm, light indicator and pump/sprinkler were activated. The measured temperature of the system was compared with the reference temperature. Results: The result showed that there was a mean deviation of 1.550C between the measured values and reference values which served as the control. Conclusion: The constructed system is compact and easy to install. The constructed fire control device is quite cheap and affordable to every category of person.

Design Analysis of 7.5KW Stand Alone Solar Photovoltaic Power System for an Intermediate Household

Aim: Design Analysis of 7.5KW Stand-alone Solar Photovoltaic Power System for an Intermediate Household. Methodology: A design analysis of standalone 7.5KW PV system was carried out using PV modeling equations based on load estimated. The analyzed data of the solar photovoltaic components was used to determine the estimated output power of 7.5KW. Therefore, a number of modeling equations and methodologies for designing a PV system based on application have been developed and simplified in order to ensure the optimum performance of the system. The analyzed solar powered 7.5KW system was achieved by designing 24 solar panels of 335W each, 16 deep cycle battery of 200A each, and a pulse width modulation (PWM) charge controller of 60A to monitor the output of the battery for safety operation. The battery will be connected to the inverter circuit (DC-AC) to generate 220V alternating current in its output via a step-up transformer. In this paper, design analysis of a standalone PV system enables of producing power to a household with approximate consumption of 7.5KW was conducted. Results: The standalone PV system along with the cost implications was analysed and designed. In this analysis a sequential design plan of an independent standalone solar powered photovoltaic structure was analysed and overviewed to supply continuous and uninterrupted power to a typical utility with maximum power consumption of 7500W (7.5KVA). The calculated/computed values of all the components yield a result that can serve the purpose. Based on the design analysis, the result implies that the estimate consumption of 7.5KW in a day requires 24 PV panels of 335 Watts each, 16 (12V, 200Ah) batteries, 10KW inverter, (12V, 60A) charge controller and copper wire of cross-sectional area (1.688mm2) for installation. Conclusion: In Nigeria, to generate a solar power of 7.5KVA requires almost $15,585.70 which is equivalent to N 5,965,426.66.

Effect of Radiation on Germanium Doped SiO2 Fibres

We report comparative effect of radiation on Germanium incapacitated Optical fibres and commercially available TLD-100. The experiments were carried out using Siemens linear accelerator (LINAC) Primus Multileaf Collimator (MLC) 3339 to deliver photon and electron beams. The Harshaw model 3500 TLD reader with WinREMS software were used in this experiment. Both media were irradiated with 6 x106 eV electrons and 6 x106 volts photons beam. We found a good linearity for TL dose in the range from 20 to 240 mGy. Comparative studies of these compounds indicate that the TL responses using photon and electron irradiation are similar and the average intensity is enhanced by about 1.30 times in electrons than those for photon irradiation. The information of the mini review report of this paper presents in valuable for clinical linear accelerators applications.