Effects of Annealing on the Structural and Optical Properties of Silver Thin Films

Silver thin films were prepared on glass substrates using chemical bath method. The thin films were annealed at different temperatures of 100 and 200oC for 1hour. The samples, as-prepared and annealed were  characterized using X-ray diffractometer (XRD) and Uv-Vis  spectrophotometer. XRD results revealed that silver films present a cubic phase with (111) preferred orientation. The XRD result and analysis also revealed that the intensity of the peaks and the crystallite size increase with increase in annealing temperature. All the films showed very low transmittance within the visible region with the 200oC annealed film having the highest at 1.4%. Reflectance was found to reduce from 65% for the as-deposited film to as low as 17% for the 200oC annealed film within the visible region of the wavelength. The reflectance reduces with increase in annealing temperature. The films also showed low percentage absorbance within the UV region of the wavelength with the 200oC annealed film having the highest absorbance of 2.79%.Keywords: Annealing, Thin films, XRD, Optical properties, Spectrophotometer, Silve

Geothermal Energy Potential of the Chad Basin, North-Eastern Nigeria

In this research paper, the sub-surface heat flow of a part of the Chad Basin, in North eastern Nigerian was estimated using spectral analysis. This was obtained from twenty (20) digitized High Resolution Aeromagnetic (HRAM) data sheet covering the study area. Regional-residual separation using first order polynomial fitting method with three coefficients was carried out on the data map before the application of statistical spectral analysis. Result shows that the centroid depth varies between 9.39 km and 18.31 km. The depth to the Curie temperature isotherm varies between 15.14 km and 33.46 km below the mean sea level. It was also found that the Curie temperature isotherm within the basin is not a horizontal level surface but an undulating surface with geothermal gradients and heat flow ranging between 15.77 and 38.31°C/Km, and 39.41 and 95.77 mWm-2 respectively. Thus, the calculated average geothermal gradient and heat flow for this area are 23.39°C/Km and 58.47 mWm-2 respectively. Since average heat flow in thermally normal continental region is 60 and the values in excess of 80 mWm-2 – 100 mWm-2 are associated with anomalous geothermal conditions, hence the study area can generally be considered as a thermally normal region. But, the northeastern part of the study area with values in excess of 80 mWm-2 is recommended for further investigationKeywords: Geothermal energy, Spectral Analysis, Chad Basin. Curie point dept

Determination of Magnetic susceptibility of hydrocarbon contaminated soils in Port Harcourt and Bonny Island, Rivers State, Nigeria

In this study, determination of magnetic susceptibility were carried out on 366 soil samples using MS2B magnetic susceptibility meter connected to a computer system using MULTISUS2 software. The soil samples were selected from six sites namely: Shell environment, Nigeria Liquefied Natural Gas environment, Port Harcourt Refining Company James Hart, New Jerusalem and Port Harcourt respectively. Three of the six sites; Shell, NLNG and Port-Harcourt Refining Company environments have their soils contaminated with hydrocarbon. One hundred and ninety two (192) soil samples were collected from these hydrocarbon contaminated sites and 174 from non-hydrocarbon contaminated soil (control samples). The magnetic susceptibility values obtained from Shell environment and for hydrocarbon samples showed higher (enhanced) magnetic susceptibility with average values of 117.54x10-8 m3kg-1 and 2016.39x10-8 m3kg-1 and a moderate magnetic susceptibility for with an average value of 20.83x10-8 m3kg-1 in comparison to magnetic susceptibility values obtained from the control samples whose average values were 2.39x10-8 m3kg-1, 12.42x10-8 m3kg-1 and 3.31x10-8 m3kg-1 for James Hart, New Jerusalem and Port Harcourt respectively. This means that the hydrocarbon sites are highly magnetic which could be indication of pollution. The results of the percentage frequency dependent susceptibility (χFD%) obtained in the hydrocarbon samples showed about 16% of the samples had percentage frequency dependent susceptibility (χFD%) values between 0-2%, 53% had values of χFD% between 2-10% and 31% had χFD% between 10-12% and above while about 21% of the control samples had χFD% values between 0-2%, 58% between 2-10% and 21% between 10-12% and above. The high magnetic susceptibility value in the hydrocarbon soil samples is an indication of pollution due to hydrocarbon deposit. The Government is therefore advised to monitor the location and activities of the oil companies and initiate quick mop up strategies should be put in place in the eventuality of oil spillage

Assessment of heavy metal pollution in drinking water due to mining and smelting activities in Ajaokuta, Nigeria

Mining and smelting activities are the main causes for the increasing pollution of heavy metals from water sources. The toxicity of these heavy metals from the mining, milling and smelting companies can cause harmful and even lethal effects on the human health. The objective of this study was to investigate the level of As, Cr, Zn, Mg, Fe, Pb, Cd, Cu, Ag and Mn in well and tap water and assess the degree of pollution in the study area. Atomic Absorption Spectrometry investigation was carried out on 60 samples of water (Well and Tap) collected within and outside the mining and smelting area of Ajaokuta to determine the extent of these heavy metals contamination in their drinking water. The data of heavy metal concentrations reveal that the area has been slightly contaminated with the heavy metals, with As and Cr having the highest level of contamination. Correlation analysis between the selected heavy metals was conducted to further investigate the relationship between the metals. The result shows that these selected metals have common pollution sources related to the mining and smelting activities in the area.Keywords: Heavy metals, atomic absorption spectrometry (AAS), smelting, pollution, well wate

Radiological Impacts of Natural Radioactivity in Locally Produced Tobacco Products in Ibadan, Oyo State, Nigeria

Radionuclides are found naturally in air, water and soil. They are even found in vegetation, consumer products and in human body. Everyone on the planet is exposed to some background level of ionizing radiation through external exposures that occurs as a result of irradiation, and internal exposures that occurs as a result of ingestion and inhalation. Studies have shown that tobacco contains minute quantities of radioisotopes from uranium and thorium-decay series which are radioactive and carcinogenic. Tobacco product increases both external and internal exposure due to these radioisotopes. In fact, tobacco products have been considered to be one of the most significant causes of lung cancer. Owing to the large-scale consumption of tobacco in Nigeria at the present time, locally produced tobacco products in Nigeria were collected from the market and the naturally-occurring 238U and 232Th decay series, as well as non-series decay 40K in these products were measured using γ-ray spectrometer. The radiological impacts of the radionuclides in these products were assessed from their specific activities. The average values of the absorbed dose rate were 19.72 and 17.59 nGy h-1 for snuff and cigarette products respectively. The average values of the effective doses due to daily inhalation of smoke by consumers from one wrap of snuff and one stick of cigarette products is 592.32 and 66.62 μSv yr-1 respectively. Similarly, the values of the radium equivalent activity index for snuff and cigarette samples were 40.95 and 38.95 Bq kg-1 respectively. Also the external radiation hazard index were 0.12 and 0.11 for snuff and cigarette samples respectively while the internal radiation hazard index were 0.17 and 0.15 for the two samples respectively. The average excess lifetime cancer risk (x 10-3) values for daily inhalation of smoke from one wrap of snuff and one (1) stick of cigarette were 2.07 and 0.23 x 10-3 respectively. The estimated values of some of these parameters were found to be lower than the recommended limit by UNSCEAR (2000). However, the effective dose poses a serious health risk to addicted consumers of the product when three (3) or more wraps of snuff and one (1) or more packs of cigarette products are consumed daily. The mean excess lifetime cancer risks values estimated were also much higher than the recommended limits by UNSCEAR (2000). This then makes the risk of suffering cancer and other radiation injuries to be high.Keywords: Radiological impacts, Tobacco, Cigarette, Snuff, Cancer, Radiation injury, Nigeria

Determination of selected heavy metals and human health risk assessment in fishes from Kiri Dam and River Gongola, Northeastern Nigeria

The concentrations of Pb, Cd, Cr, Fe and As in the Catfish and Tilapia from Kiri Dam and River Gongola, Northeastern Nigeria were analyzed using Atomic Absorption Spectrometer (AAS). The result reveals that these selected heavy metals are higher in Catfish than Tilapia irrespective of the location. Assessment of the health risks due to consumption of these fishes suggests that both fishermen and the general populace are not subjected to a significant potential health risk. The results of this study regarding metal contents in fishes from the study areas also suggest that theconsumption of catfish and tilapia from the study area is not free of risks. And that the complex THQ and TTHQ parameters used in health risk assessment of heavy metals provides a better image than using only a simple parameter like the content of the metals in the samples