https://www.ajol.info/index.php/sa/issue/feed Scientia Africana 2021-03-09T11:12:44+00:00 Gabriel O. Agu gabriel.agu@uniport.edu.ng Open Journal Systems <!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning /> <w:ValidateAgainstSchemas /> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables /> <w:SnapToGridInCell /> <w:WrapTextWithPunct /> <w:UseAsianBreakRules /> <w:DontGrowAutofit /> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0pt; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> <!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0pt 5.4pt 0pt 5.4pt; mso-para-margin:0pt; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--><span style="font-size: 10pt; font-family: Arial;" lang="EN-GB"><em>Scientia Africana</em> seeks to encourage communication among scientists all over the world through regular publication of their research findings. The journal publishes results of original research in all aspects of biological, chemical, earth, mathematical, physical and applied sciences including basic medical and engineering sciences. It also publishes review articles, book reviews, research notes and other short communications on all aspects of pure and applied sciences and accepts advertisements in related fields.</span> https://www.ajol.info/index.php/sa/article/view/204163 Editorial 2021-02-23T13:31:49+00:00 G. O. Avwiri gregory.avwiri@uniport.edu.ng <p>No Abstract.</p> 2021-02-23T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204164 Application of electrical and magnetic geophysical methods in depth estimation of potential mineral depositat Olabisi Onabanjo University, Ago Iwoye, Southwestern Nigeria 2021-02-23T14:16:09+00:00 J.O Coker coker.joseph@oouagoiwoye.edu.ng A.E. Akinmoladun coker.joseph@oouagoiwoye.edu.ng A.J. Agbelemoge coker.joseph@oouagoiwoye.edu.ng S.O. Ariyo coker.joseph@oouagoiwoye.edu.ng O.O. Bayewu coker.joseph@oouagoiwoye.edu.ng G.O Mosuro coker.joseph@oouagoiwoye.edu.ng A.O. Alaka coker.joseph@oouagoiwoye.edu.ng <p>Geophysical techniques are powerful tools in depth estimation of minerals deposits. This survey was carried out to evaluate the nature and&nbsp; depth of mineral deposits near the Sports complex of Olabisi Onabanjo University (OOU), Ago-Iwoye.’. A total of five (5) Vertical Electrical Soundings (VES) points were investigated using Pasi Terrameter. The spread across the area using the Schlumberger&nbsp; configuration was with a maximum current electrode separation of 100m. The results obtained were interpreted quantitatively and&nbsp; qualitatively using partial curve matching and computer iteration programs known as WINRESIST and SURFER 11. Also, forty one (41) survey profiles were taken at a station interval of 5m using the GEM Magnetometer to acquire the Total Magnetic Intensity reading. The Guassian filter-Oasis Montaj was used for the computation of regional field from the observed TMI readings of the area. The geologic and<br>structural map reveals a few visible fractured zones imbedded in the migmatite-gneiss deposits which spread from the northwest to the southern and eastern part of the study area and the granite gneiss was seen around the Southwestern and Northern parts. The delineated fractures could potentially serve as geologic traps for mineral localization. The 2D radial average power spectrum indicates that, the northeast part of the mapped area has a depth of 4.5mand a depth of 13m at the eastern part. It can be seen that the depth are shallow and there are visible outcrops at the study area.The approximate depth to the mineral deposit was determined using the standard Euler solution to be around 13 m and the elevation range obtained varies between 37 m – 50 m. The correlation of the electrical and magnetic techniques shows that both methods are able to give the estimated depth of shallow mineral deposit which range between 13 m – 18m.</p> <p><strong>Keywords</strong>: Euler solution, Geophysical Techniques, Lithology, Total Magnetic Intensity, Vertical Electrical Sounding.</p> 2021-02-23T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204169 Valuation of hydraulic fracturing potentials of organic-rich shales from the Anambra basin using rock mechanical properties from wireline logs 2021-02-24T07:24:21+00:00 Homa Viola Akaha-Tse gabriel.agu@uniport.edu.ng Michael Oti gabriel.agu@uniport.edu.ng Selegha Abrakasa gabriel.agu@uniport.edu.ng Charles Ugwu Ugwueze gabriel.agu@uniport.edu.ng <p>This study was carried out to determine the rock mechanical properties relevant for hydrocarbon exploration and production by hydraulic&nbsp; fracturing of organic rich shale formations in Anambra basin. Shale samples and wireline logs were analysed to determine the petrophysical, elastic, strength and in-situ properties necessary for the design of a hydraulic fracturing programme for the exploitation of the shales. The results obtained indicated shale failure in shear and barreling under triaxial test conditions. The average effective porosity of 0.06 and permeability of the order of 10<sup>-1</sup> to 10<sup>1</sup> millidarcies showed the imperative for induced fracturing to assure fluid flow. Average Young’s modulus and Poisson’s ratio of about 2.06 and 0.20 respectively imply that the rocks are favourable for the formation and propagation of fractures during hydraulic fracking. The minimum horizontal stress, which determines the direction of formation and growth of artificially induced hydraulic fractures varies from wellto-well, averaging between 6802.62 to 32790.58 psi. The order of variation of the in-situ stresses is maximum horizontal stress&gt;vertical stress&gt;minimum horizontal stress which implies a reverse fault fracture regime. The study predicts that the sweet spots for the exploration and development of the shale-gas are those sections of the shale formations that exhibit high Young’s modulus, low Poisson’s ratio, and high brittleness. The in-situ stresses required for artificially induced fractures which provide pore space for shale gas accumulation and expulsion are adequate. The shales possess suitable mechanical properties to fracture during hydraulic fracturing. Application of these results will enhance the potentials of the onshore Anambra basin as a reliable component in increasing Nigeria’s gas reserves, for the improvement of the nation’s economy and energy security.</p> <p><strong>Key Words</strong>: Hydraulic Fracturing, Organic-rich Shales, Rock Mechanical Properties, Petrophysical Properties, Anambra Basin</p> 2021-02-24T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204170 Heavy metal levels in cassava flour sold in Okura, Ejule and Ojapata of kogi state, Nigeria 2021-02-24T07:35:03+00:00 Olubiyo Gloria Taiye glotaiye2016@gmail.com Yakubu Anita Ohunene glotaiye2016@gmail.com Olubiyo Comfort Kehinde glotaiye2016@gmail.com <p>Cassava (Manihot esculenta) is a major source of carbohydrate and a staple food cultivated in Nigeria especially in Kogi&nbsp; State. Determination of heavy metals in cassava flour from major markets:(Okura ,Ejule and Ojapata) in Kogi East was done to ascertain the quality of cassava flour and its human exposure path.Lead, cadmium, iron and zinc contents were determined using Atomic Absorption Spectrophotometer (AAS).The results were analysed using Analysis of Variance (ANOVA), Duncan Multiple Range Test (DMRT) and&nbsp; Independent Sample t-test. Zn concentration in Ejule (Control) was as low as 0.002±0.000a . Pd,Cd,Fe, and Zn screened were far below the WHO guideline values or permissible limit of metal in food.This implies that the metal toxicants present in the cassava flour is in such low concentrations that render the food non-toxic and edible.</p> <p><strong>Keywords</strong>: Heavy metals; pollution; cassava flour; human exposure. </p> 2021-02-24T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204171 Effects of <i>Alchornea cordifolia</i> leaf extract on the mechanical properties of mild steel in acidic medium 2021-02-24T07:48:30+00:00 E. Oparaku oparaku35@gmail.com E. Osarolube oparaku35@gmail.com <p>The effect of <em>Alchornea Cordifolia</em> leaf extract on the mechanical properties of mild steel in acidic medium was studied using weight loss method. The first sample was not introduced to any medium. It served as the control<sup>1</sup> sample. The second sample was introduced to a medium containing 0.2M Sulphuric acid solution in the absence of the <em>Alchornea Cordifolia</em> leaves extract for 21 days, while the third sample was immersed in a vessel containing 0.2M sulphuric<sup>2</sup> acid and 0.5g/L of <em>Alchornea Cordifolia</em> leaves extract as an inhibitor for 21 days. Results obtained showed a substantial improvement on the mechanical properties of mild steel exposed to the medium with the inhibitor.</p> <p><strong>Keywords</strong>: Mechanical Properties, Corrosion, Inhibition, <em>Alchornea Cordifolia,</em> Sulphuric acid</p> 2021-02-24T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204172 Detailed quantitative sequence stratigraphic interpretation for the characterization of Amangi field using seismic data and well logs 2021-02-24T08:21:25+00:00 S. Inichinbia sonny.inichinbia@yahoo.com Halidu Hamza sonny.inichinbia@yahoo.com <p>The sequence stratigraphy of Amangi field of the Niger Delta was studied using seismic data and well logs. The field is a structurally&nbsp; complex one and presents serious challenges to hydrocarbon exploration and production. The main objective of these analyses is to&nbsp; identify sand intervals using the available data. Well log data were used as additional tools to constrain the seismic correlations in order to solve the correlation problem. The well logs were evaluated for the field’s petrophysical properties by combining the gamma ray and resistivity logs to determine reservoir zones with considerable hydrocarbon saturation. Also, the relationship between some basic rock properties/attributes and litho-types were determined for the study area. Next, well-to-seismic ties were produced and two horizons were picked. Acoustic impedance inversion was also performed which revealed “hard sands” due to mixed lithologies (heterolithics). This made it difficult to discriminate the sands from shales in the P-impedance domain alone. So, progress was made to determine the net-to-gross of the field. The analysis revealed that these reservoirs have shaly sand with shale content of 10%, porosity averaging 21%, and hydrocarbon saturation of 90%. The result established a vertical stack of a series of reservoirs in an anticlinal structure of which the H1000 and H4000 stand out for their huge volumes of rich gas condensate accumulation. This discovery provoked the drive for the first phase of development of this field.</p> <p><strong>Keywords</strong>: stratigraphy, facies, net-to-gross, horizon, lithology, well-to-seismic tie, impedance </p> 2021-02-24T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204174 Evidence of terrestrial organic carbon inputs on Niger Delta Sea Shelf 2021-02-24T08:26:31+00:00 M.U. Uzoegbu uche.uzoegbu@uniport.edu.ng <p>The objective of this research is to determine the actual source of organic matter in the Niger Delta Sea Shelf (NDSS). Organic carbon (OC) and n-alkanes were investigated in the suspended matter (SM) and surfcial sediments of the Niger and Imo Rivers and the opposite Niger Delta Sea Shelf. Organic nitrogen and carbon isotope (δ13C) values were determined as additional parameters in the sediments. OC and n-alkane concentrations were highly variable. This variability was interpreted as the result of sources of materials from the inland basins and a complex sedimentation pattern involving the discharges of these two rivers. Using the constant ratio of high molecular weight odd n-alkanes to OC in both rivers, the estimated value of more than 70% of the OC preserved in shelf sediments were terrestrially-derived. This result was substantiated by the overall dominance of land-derived n-alkanes. A second approach using δ13C values and assuming binary dilution of riverine and marine OC led to the determined source of organic matter.</p> <p><strong>Keywords</strong>: Organic carbon; δ13C; n-Alkanes; Niger River; Imo River; Niger Delta Sea Shelf.&nbsp; </p> 2021-02-24T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204175 A methodology for e-banking risk assessment using fuzzy logic and Bayesian network 2021-02-24T08:52:57+00:00 Ako Rita Erhovwo ochukorita2@gmail.com Okpako Abugor Ejaita ochukorita2@gmail.com Duke Oghorodi ochukorita2@gmail.com <p>Risk assessment methodology in general has been around for quite a while, its prominence in the E-banking field is a fairly recent phenomenon. We are at the point where risk assessments are critical to the overall function of banks. Banks are required to assess the processes underlying their operations against potential threats, vulnerabilities, and their potential impact, which helps in revealing the risk exposure level, and the residual risks. Identifying clearly a risk assessment methodology is often the first step of assessing and evaluating risk associated with an organization operation. This paper presents a risk assessment methodology for Ebanking Operational Risk. The proposed risk assessment methodology consists of four major steps: a risk model, assessment approach, analysis approach and a risk assessment process. The main tool of the proposed risk assessment methodology is the risk assessment process. The assessment process gives detailed explanation with respect to which models or techniques may be applied and how they are expressed. In this paper the risk assessment technique is built upon fuzzy logic (FL) concept and Bayesian network (BN). In fuzzy logic, an element is included with a degree of membership. Bayesian network is an inference classifier that is capable of representing conditional independencies. The Bayesian and fuzzy logic–based risk assessment process gives good predictions for risk learning and inference in the E-banking systems.</p> <p><strong>Keywords:</strong> Fuzzy logic, Bayesian network, risk assessment methodology, operational risk, Ebanking </p> 2021-02-24T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204177 Seismic-to-well tie of a field of the Nigerian Delta 2021-02-24T09:06:56+00:00 S. Inichinbia Sonny.inichinbia@yahoo.com A.L. Ahmed Sonny.inichinbia@yahoo.com <p>This paper presents a rigorous but pragmatic and data driven approach to the science of making seismic-to-well ties. This pragmatic&nbsp; approach is consistent with the interpreter’s desire to correlate geology to seismic information by the use of the convolution model,&nbsp; together with least squares matching techniques and statistical measures of fit and accuracy to match the seismic data to the well data. Three wells available on the field provided a chance to estimate the wavelet (both in terms of shape and timing) directly from the seismic and also to ascertain the level of confidence that should be placed in the wavelet. The reflections were interpreted clearly as hard sand at H1000 and soft sand at H4000. A synthetic seismogram was constructed and matched to a real seismic trace and features from the well are correlated to the seismic data. The prime concept in constructing the synthetic is the convolution model, which represents a seismic reflection signal as a sequence of interfering reflection pulses of different amplitudes and polarity but all of the same shape. This pulse shape is the seismic wavelet which is formally, the reflection waveform returned by an isolated reflector of unit strength at the target&nbsp; depth. The wavelets are near zero phase. The goal and the idea behind these seismic-to-well ties was to obtain information on the sediments, calibration of seismic processing parameters, correlation of formation tops and seismic reflectors, and the derivation of a&nbsp; wavelet for seismic inversion among others. Three seismic-to-well ties were done using three partial angle stacks and basically two formation tops were correlated.</p> <p><strong>Keywords</strong>: seismic, well logs, tie, synthetics, angle stacks, correlation, </p> 2021-02-24T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204178 Computational analyses of heat flux of wall Y<sup>+</sup> in supercritical fluid using star – Ccm+ Cfd code 2021-02-24T09:15:34+00:00 Omamoke O. E. Enaroseha enarosehaomamoke@gmail.com Ernest Ogheneruona Ojegu enarosehaomamoke@gmail.com <p>Theoretical modeling techniques on resolving turbulent heat flows in a nondimensionalcircular tube mounted obstacle using the wall Y+ as guidance in selecting the appropriate grid configuration and corresponding turbulence models are investigated using CFD Code. The results obtained shows that the heat fluxes of 20, 23, 30 and 40 kW/m<sup>2</sup>, increases as the Y<sup>+</sup>wall profile moves away from the near – wall region, this is due to the effect of viscosity, buoyance, acceleration and the friction of the turbulence modification.The results also indicates that the low Y<sup>+</sup>wall treatment is suitable only for low Reynolds turbulence models in which it is assumed that the viscous sub-layer is&nbsp; properly resolved. The simulated results obtained in this research are in good agreements with the experimental results in the literature,<br>even though they over predicted the observed heat transfer deterioration both quantitatively and qualitatively.</p> <p><strong>Keywords</strong>: Wall Y<sup>+</sup> , Turbulence, Supercritical fluid, Heat flux </p> 2021-02-24T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204179 Assessment of ionizing radiation exposure levels and associated health risk in some selected solid mineral mining sites Edo-North, Nigeria 2021-02-24T12:55:09+00:00 A.O. Eshiemomoh alsiv2002@yahoo.com G.O. Avwiri alsiv2002@yahoo.com C.P. Ononugbo alsiv2002@yahoo.com <p>Ionizing radiation exposure rate and its associated health risks were assessed using Digilert 200 and Rados Radiation Monitoring Meter, integrated with Geographical Positioning System (Garmin GPSMAP 76S) of some selected solid mineral mining sites across Edo-North Nigeria. The mean exposure rates show some characteristic range of 0.010±0.005 𝑚𝑅ℎ𝑟<sup>−1</sup> to 0.027 𝑚𝑅ℎ𝑟<sup> −1</sup> across the entire study. The obtained mean exposures rates at all the mining pits were higher than the ICRP standard limit of 0.013 𝑚𝑅ℎ𝑟 <sup>−1 </sup>, except at freedom limestonesmining pit where we recorded 0.010 mRh<sup>-1</sup>. It was also observed that limestones mining sites exhibited low exposure rate while granite mining sites exhibited high exposure rate. The computed equivalent dose rate ranges from 1.049 mSvy<sup>-1 </sup>to 2.287 mSvy<sup>-1 </sup>, which is well above the recommended permissible limit of 1.0 mSvy<sup>-1</sup> for the general public. 91.7% of the mining sites recorded higher absorbed dose rate but the mean AEDE recorded across the entire study area are below the ICRP standard. The average excess lifetime cancer risk shows variation from 0.472 x 10<sup>-3 </sup>to 1.27 x 10<sup>-3 </sup>. . By this result, the probability of contacting cancer due to radiation exposure is higher in places like Cinoma pit, Cetraco pit, Niger-Cat pit, Jigom pit, Oaries pit and Petra-Quarries pit.</p> <p><strong>Keywords</strong>: Assessment, Mining pits, Background, Exposure, lifetime cancer risk</p> 2021-02-24T00:00:00+00:00 Copyright (c) https://www.ajol.info/index.php/sa/article/view/204189 Structural, electronic, mechanical and thermodynamic properties of half-metallic rh2fez (z = ga, in) full heusler compounds from first principles 2021-02-24T13:15:12+00:00 O.E. Osafile osafile.omosede@fupre.edu.ng J.O. Umukoro osafile.omosede@fupre.edu.ng <p>We report on the structural, electronic, mechanical, and thermodynamic properties of Rh2FeGa and Rh2FeIn full Heusler alloys from first principles. Results for the structural analysis establishes structural stability with a negative formation energy of -0.2175 eV and -0.2082 eV<br>for Rh2FeGa and Rh2FeIn, respectively. The lattice constants and electronic properties compare favorably with reports from existing&nbsp; literature. The compounds are both anisotropic and mechanically stable, having checked out with the Born and Huang criteria. Rh2FeIn alloy is more ductile, yet, harder, and stiffer compared to its Rh2FeGa counterpart. The Debye temperatures of 400.124 K and 267. 738 K recorded for Rh2FeGa and Rh2FeIn, respectively, is consistent with the expectation that the main group element's atomic size has an inverse relationship with the Debye temperature. Therefore, indium with the larger atomic size has a lesser Debye temperature. Both compounds obey the Dulong-Petit limit at temperatures between 400 K and 500 K. The specific heat capacity at constant volume 𝐶𝜐 of 96.5 𝐽 𝑚𝑜𝑙<sup>−1</sup>𝐾<sup>−1</sup> and 98 𝐽 𝑚𝑜𝑙<sup>−1</sup>𝐾 <sup>−1</sup> for Rh2FeIn and Rh2FeGa alloys suggests thermodynamic stability of the compounds at moderate&nbsp; temperatures.</p> <p><strong>Keywords</strong>: Density functional theory; Density functional perturbation theory; Half-Heusler compounds; Mechanical Properties;&nbsp; Thermodynamic properties.</p> 2021-02-24T00:00:00+00:00 Copyright (c)