Browsing by Author "Yahaya, T."
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Item Assessment of deformation twinning in cold rolled austenitic stainless steels with electron back scatter diffraction(Faculty of Engineering and Technology, University of Ilorin, Nigeria, 2014) Ahmed, I. I.; Wright, D.; Adebisi, J. A.; Aremu, I. N.; Yahaya, T.; da Fonseca, J. Q.Deformation twinning has traditionally been studied with Transmission Electron Microscopy (TEM). In this study, an assessment of deformation twinning in Austenitic Stainless Steel (ASS), type 304L, cold rolled to 20% reduction was investigated using Scanning Electron Microscopy (SEM) and Electron Back Scatter Diffraction (EBSD) techniques rather than the conventional TEM. The study revealed the presence of deformation twins in the cold rolled grains of ASS. It emerged from the study that the deformation twins observed may facilitate localised heterogeneous deformation and development of internal stresses within the grain.Item Characterization, anti-inflammatory and antimicrobial potentials of a herbal preparation.(Nigerian Journal of Pharmaceutical Sciences. Published by Faculty of Pharmaceutical Sciences, Ahmadu Bello University, Zaria., 2019) Njinga, N.S.; Bakare-Odunola, M.T.; Mustapha, K.B.; Yahaya, T.; Shittu, A.O.; Bello, H. R.; Abdullahi, S.T.; Usman, S.O.; Ayanniyi, R.O.; Olufadi-Ahmed, H.Y.The stem bark of Lannea kerstingii Engl. & K. Krause was investigated for its phytochemistry, acute toxicity, antibacterial and anticonvulsant activit ies. Standard methods were used to evaluate phytochemistry while antibacterial activity was determined using agar diffusion and broth dilution method s on Staphylococcus aureus, Salmonella typhii, Pseudomonas aeruginosa, Klebsiella pneumonia, Proteus vulgaris, Escherichia coli and Bacillus subtilis. Maximal electroshock-induced seizures test in chicks and pentylenetetrazole-induced seizures test in mice were used to determine the anticonvulsant activity. Phytochemical studies revealed the presence of flavonoids, tannins, carbohydrates steroids and triterpenes. Ethyl acetate and methanol fractions of the stem bark were found to be active against S. aureus, S. typhi, P. aeruginosa, K. pneumoniae, Proteus sp, E. coli, Bacillus subtilis with zone of inhibition ranging from 20-27.5mm and MIC ranging from 6.25mg/mL to 100mg/mL and MBC from 50mg/mL and above. LD50 was found to be 2154.066 mg/kg. The crude methanol extract of the stem bark afforded dose (150, 300 and 600mg/kg) dependent protection to the laboratory animals against the hind limb tonic extension though not statistically significant (P<0.05) showing the inability of the extract to inhibit seizure discharge within the brainstem seizure substrate. Meanwhile the extract at doses of 300 and 600mg/kg significantly (P<0.05) prolonged the onset of seizure in pentylenetetrazole (PTZ) test showing the potential of this plant in raising seizure threshold in the brain therefore making it beneficial in the treatment of myoclonic and absence seizures. This justifies the use of the plant in treating convulsion.Item Characterization, anti-inflammatory and antimicrobial potentials of herbal preparation(Faculty of Pharmaceutical Sciences, A.B.U Zaria, 2019) Njinga N.S.; Bakare-Odunola, M.T.; Mustapha, K.B.; Yahaya, T.; Shittu A.O.; Bello, H.R.; Abdullahi, S.T.; Usman, S.O.; Ayanniyi, R.O.; Olufadi-Ahmed, H.Y.Herbal product (HP) (from Ricinus communis and honey) is used locally for the management of inflammatory and inflammation related disorders including asthma. The current study was carried out to determine the phytochemicals, total phenolic and flavonoid contents, chemical profile, elemental components, anti-inflammatory and antimicrobial activity of the HP used for treatment of asthma. Total phenolic and flavonoid contents were determined by the Folin-Ciocalteus reagent and AlCl3 colorimetric method respectively. The chemo-profiling was done using TLC. Elemental analysis was determined using Atomic Absorption Spectroscopy (AAS). Albumin-induced paw oedema model was used to determine the anti-inflammatory activity while agar well diffusion method was used to determine the antimicrobial activity of the HP at different concentrations. Flavonoids, saponins, alkaloid, cardiac glycoside, steroids and terpenoids were detected in the HP. Total phenolic and flavonoid contents obtained were 10.00 mg/g gallic acid equivalent and 336.60 mg/g quercetin equivalent respectively. The chemo-profiling showed one spot at 254 nm but none at 366 nm. AAS indicated the presence of K, Ca, Fe, Na, Zn, Cu and Pb (Cu and Pb were within WHO acceptable limit). The 100 % concentration produced sudden but transient significant reduction in oedema size at 30 minutes. However, at 60 minutes the effect produced at 25 % was comparable to that of Ibuprofen at 20 mg/kg body weight. At 100% concentration HP all the organisms tested were sensitive except for Pseudomonas aeruginosa. The presence of flavonoids may justify the anti-inflammatory and antimicrobial activities thus validating its use in local treatment of AsthmaItem Combustion characteristics of bio-degradable biomass briquettes(School of Engineering, Taylor’s University, Malaysia, 2018) Abdulkareem, S.; Hakeem, B. A.; Ahmed, I. I.; Ajiboye, T. K.; Adebisi, J. A.; Yahaya, T.This paper reports on the combustion characteristics of biodegradable biomass briquettes prepared from charcoal, sawdust and sugarcane bagasse. The three materials were mixed in respective ratio of 20:20:60, 20:30:50, 20:40:40, 20:50:30 and 20:60:20. The briquettes were produced using Budenberg dial gauge hydraulic compression machine with the formation of briquettes under 64 MPa pressure with 120 seconds dwell time. Combustion characteristics such as proximate analysis, fuel-burning rate, fuel ignition time and afterglow time of the produced briquettes were determined. Results show that briquette with sample composition of 20:50:30 has better calorific value of 24613.69 kJ/kg and sample with ratio 20:30:50 has lowest calorific value of 22500.3 kJ/kg, while sampling with ratio 20:30:50 has better physical properties with shatter resistance of 99.61% and porosity index value of 47.40%.Item Design, Fabrication and Performance Evaluation of Awning/Canopy for Thermal Comfortability(Journal of Engineering and Technology, 2017) Ajao, K.R.; Yahaya, T.; Kolawole, M.Y.; Aweda, J.O.This paper presents the design, fabrication and performance evaluation of retractable awning/canopy system for thermal comfortability. It consists of frame (mild steel bars), linear actuator, fabric (acrylic), adapter, roller pathways and photo sensor (for easiness of control). After fabrication and coupling of the whole components of the retractable awning and connecting to the adapter and power source for performance test evaluation, it was observed that, the actuator arm which was coupled to the fabric began projecting outward and once the photo sensor was shaded from sunlight using a dark material, the fabric retracted into the roller. Also it was noted that, shading the window provided a reduced solar heat gain factor of 28.16W as compared to the solar gain factor of 498.54 W before shading the window with a cooling load of 415.37 W achieved. This can be incorporated into a building plans especially those at the sun heating direction and temperature region to reduce inner temperature aid air-conditioner loading for longer life and efficient operation.Item Effect of welding variables on mechanical properties of low carbon steel welded joint(Production Engineering Institute (PEI), Faculty of Mechanical Engineering, University of Maribor, Slovania, 2014) Talabi, S. I.; Owolabi, O. B.; Adebisi, J. A.; Yahaya, T.This paper discussed the effect of welding variables on the mechanical prop-erties of welded 10 mm thick low carbon steel plate, welded using the Shield-ed Metal Arc Welding (SMAW) method. Welding current, arc voltage, welding speed and electrode diameter were the investigated welding parameters. The welded samples were cut and machined to standard configurations for tensile, impact toughness, and hardness tests. The results showed that the selected welding parameters had significant effects on the mechanical properties of the welded samples. Increases in the arc voltage and welding current resulted in increased hardness and decrease in yield strength, tensile strength and impact toughness. Increasing the welding speed from 40-66.67 mm/min caused an increase in the hardness characteristic of the welded samples. Initial decrease in tensile and yield strengths were observed which thereafter increased as the welding speed increased. An electrode diameter of 2.5 mm provided the best combination of mechanical properties when compared to the as received samples. This behaviour was attributed to the fact that in-creased current and voltage meant increased heat input which could create room for defect formation, thus the observed reduced mechanical properties.Item Effect of welding variables on mechanical properties of low carbon steel welded joint(Production Engineering Institute (PEI), Faculty of Mechanical Engineering, University of Maribor, Slovania, 2014) Talabi, S. I.; Owolabi, O. B.; Adebisi, J. A.; Yahaya, T.This paper discussed the effect of welding variables on the mechanical prop-erties of welded 10 mm thick low carbon steel plate, welded using the Shield-ed Metal Arc Welding (SMAW) method. Welding current, arc voltage, welding speed and electrode diameter were the investigated welding parameters. The welded samples were cut and machined to standard configurations for tensile, impact toughness, and hardness tests. The results showed that the selected welding parameters had significant effects on the mechanical properties of the welded samples. Increases in the arc voltage and welding current resulted in increased hardness and decrease in yield strength, tensile strength and impact toughness. Increasing the welding speed from 40-66.67 mm/min caused an increase in the hardness characteristic of the welded samples. Initial decrease in tensile and yield strengths were observed which thereafter increased as the welding speed increased. An electrode diameter of 2.5 mm provided the best combination of mechanical properties when compared to the as received samples. This behaviour was attributed to the fact that in-creased current and voltage meant increased heat input which could create room for defect formation, thus the observed reduced mechanical properties.Item Hardness and Tensile Properties of Prophylactic Knee Brace Produced from Cow bone and Periwinkle Shell Composites.(Published by Deer Hill Publications, B-19-06 PV8, Platinum Hill Condominium Jalan Melati Utama, 53100 Kuala Lumpur Malaysia., 2019-06-20) Abdulkareem, S.,; Adekaye, T. A.,; Abdulrahim, A. T.; Shuaib-Babata, Y. L.,; Ajiboye, T. K.,; Ahmed, I. I.,; Ibrahim, H. K.,; Adebisi, J. A.; Yahaya, T.Application of reinforced aluminium scrap for the production of prophylactic knee brace (Pkb) particularly with agrowaste materials is rarely available. In this work, hardness and tensile properties of aluminium alloy (Al 6063) straps reinforced with cow bone (Cb) and periwinkle shell (Ps) for the production of Pkb were investigated. The Cb and Ps sourced were cleaned and the Cb was sun-dried for 4 weeks before crushing with Denver laboratory Ball mill (Model: 48-D0500/Q). The Ps was also crushed, sun-dried for 7 days and treated in the oven (Model SDO/225) at 110 oC for 30 minutes to remove moisture. The particle size of 75 µm was used to cast six (6) each of aluminium/cowbone (Al/Cb) and aluminium/periwinkle shell (Al/Ps) composites. The cast aluminium composites of Pkb and original Pkb were investigated for density, hardness, and tensile properties. It was observed that addition of Cb and Ps in the cast Pkb gave a density of 2.68 g/cm3 and 2.60 g/cm3 respectively. The average values of hardness and tensile strength obtained were 41.18 BHN and 135.88 MPa respectively when Ps was added to the cast aluminium Pkb, while addition of Cb gave harness values of 40.45 BHN and tensile strength of 134.63 MPa.Item Microstructural correlation of hardness profile in martensitic stainless steel weldment(Springer, 2016) Ahmed, I. I.; Adebisi, J. A.; Yahaya, T.; Abdulkareem, S.; Sherry, A. H.The correlation between microstructures and hardness profiles in low carbon martensitic stainless steel girth weldment were investigated. Optical microscopy and a scanning electron microscope equipped with electron back scatter diffraction system were used for assessment of microstructural phases, grain sizes, and grain misorientation across the weldment. The hardness value fluctuated between the peak and lowest values in the heat-affected zone of the weldment. The hardness profile observed is consistent with microstructural evolution across the weldment. The low hardness value observed in the weld metal was attributed to the large proportion of ferrite introduced by the superduplex filler metal used for the fabrication and grain coarsening caused by prolonged cooling of the weld metal. The electron backscatter diffraction data showed that higher grain sizes occurred in the weld metal and this is consistent with the highest degree of misorientation and recrystallisation observed in the weld metal than parent and HAZ region of weldment.Item Physical and Mechanical Characteristics Of Charcoal, Sawdust and Sugarcane Bagasse as Solid Fuel Materials(Universiti Teknikal Malaysia Melaka (UTeM), 2017) Abdulkareem, S; Badejo, H. A.; Ahmed, I. I.; Adebisi, J. A.; Yahaya, T.; Ajiboye, T. K.; Abdulrahim, A. T.This paper reports on the physical and mechanical characteristics of briquettes produced from charcoal, sawdust and sugarcane bagasse using molasses with sodium silicate as binders. Charcoal, sawdust and sugarcane bagasse were mixed in a respective ratio of 20:20:60, 20:30:50, 20:40:40, 20:50:30 and 20:60:20. The briquettes were produced using Budenberg dial gauge compression machine, with a pressure of 64 MPa at 120 seconds dwell time. Physical properties (relaxation ratio, compaction ratio and shattering index) and mechanical property (compressive strength) of the produced briquettes were investigated. Results show that briquette with sample composition of 20:30:50 has better physical properties with a relaxation ratio of 1.562, a compaction ratio of 7.573 and shatter index of 99.6%, while sample with ratio 20:40:40 has the highest compressive strength of 55.43 kN/m2.Item Stress corrosion cracking of austenitic stainless steels in chloride environment(Faculty of Engineering, Ahmadu Bello University, Zaria, Nigeria, 2015) Ahmed, I. I.; Alabi, A. G. F.; Odusote, J. K.; Aremu, I. N.; Adebisi, J. A.; Yahaya, T.; Talabi, S. I.; Yahya, R. A.; Lyon, S. B.This study was carried out to assess the effect of applied potentials on Stress Corrosion Cracking (SCC) of Austenitic Stainless Steels (ASS), Type 304L in a potentiostatically controlled chloride environment at ambient temperature. The stress corrosion cracking tests were carried out on annealed ASS using a Slow Strain Rate Test (SSRT) technique in sodium chloride solution acidified with hydrochloric acid at ambient temperature. Analyses of failed specimens were carried out using optical microscope. The study showed that plastic elongation, ultimate tensile strength and time to failure decrease as the applied potential increases during the slow strain rate test. The study showed that immunity of ASS to chloride SCC was improved when the electrochemical potential was maintained in the primary passive potential range. Analysis of failed samples showed evidences of SCC.