Volume 3, Issue 2, 2015

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    Open Access
    Evaluation of Mechanical Properties of Cast Aluminum Connecting Rod for G-300 Honda Generator
    (University of Lagos Press, Akoka, 2015) Abdulkareem, S; Khan, R.H; Kolawole, M.Y
    This paper evaluated the mechanical properties of cast aluminum connecting rod, produced from recycled similar aluminum rod, in relation to imported rod. This was done via a permanent casting technique after which the tensile and hardness properties of the produced connecting rod was determine using universal tensometer with serial number UTM 10584 and Avery universal hardness testing machine (ASTM D789) respectively. Mechanical property characterizations show hardness value in the range 134 BHN – 139 BHN in the cast sample and 160 BHN – 162 BHN in the imported connecting rod. Tensile strength, percentage elongation, percentage reduction in area and yield strength in cast samples are 168 Nmm-2, 3.7 %, 7.8 % and 146 Nmm-2 respectively which are about 11 %, 34 %, 42 %, and 19 % respectively lower than those of the imported connecting rod. The difference in method of production of the two connecting rods was presumed to have been the major factor responsible for the mark difference in properties of the two rods. Though from these results, it is however presume that locally produced connecting rod through permanent casting can be made to improve in properties and compete favourably in strength with imported rod when further metallurgically heat treated via age-hardening, normalizing and solution heat treatment.
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    Open Access
    Water Quality Characteristics and Phytoplankton Diversity around a Domestic Waste Polluted Site in Lagos Lagoon
    (University of Lagos Press, Akoka, 2015) Onyema, I.C
    The water quality characteristics and phytoplankton at a domestic waste polluted site at Oworonsoki, Lagos Lagoon in relation to environmental factors were investigated for six months (October, 2012 – March, 2013). The water quality characteristics showed monthly variation linked to hydrological flow conditions, namely the rainfall pattern and tidal seawater inflow. Air temperature (28.3 – 32˚C), Water temperature (29 - 31˚C), Transparency (12.95 – 101.5cm), Total suspended solid (8 – 35mg/L), Total dissolved solid (553.0 – 20712.66mg/L), Conductivity (1069.0 – 31100.0µS/cm), Salinity (0.50 – 17.11 %), Acidity (4.9 – 6.3mg/L), Total hardness (102.0 – 3811.0 mg/L), Dissolved oxygen (4.8 – 5.2 mg/L), Chemical oxygen demand (14 – 23 mg/L) recorded higher values in the dry than in the wet season. High nutrients, especially nitrates and heavy metal levels between December and February points to the inflow of domestic wastes. The water quality characteristics reflected freshwaters situation in October and November (0.52 – 0.82 ‰) while December through March were increasingly brackish (9.42 – 17.11 %). The phytoplankton diversity (S) and abundance (N) were notably higher in the dry than the wet season. The phytoplankton spectrum (Bacillariophyta, Cyanophyta and Chlorophyta) were dominated by the Bacillariophyta (Diatoms) (93.47% - Centrales – 69.77 % and Pennales – 30.23%). Notable species of were Aulacoseira granulata var. angustissima, Odontella laevis, Coscinodiscus radiatus, Skeletonema coastasum, Chaetoceros convolutes, Bacillaria paxillifer, Gyrosigma balticum, Nitzschia sigmoidea, Synedra crystallina, Thalasiothrix fraunfeldii, Synedra ulna, Microcystis aeruginosa and Oscillatoria limnosa. The phytoplankton diversity at each time was reflective of the water chemistry situation. Comparatively, low phytoplankton diversity, and the occurrence of indicators of organic waste pollution are noteworthy.
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    Open Access
    Tool-chip Contact Length and Feed Influence on Cutting Force
    (University of Lagos Press, Akoka, 2015) Ojolo, S.J
    This paper investigates the influence of cutting process parameters such as feed, cutting speed, depth of cut and tool-chip contact length on resultant force during machining of mild steel and aluminium alloys. Forty experiments were carried out on aluminium and mild steel alloys based on cutting parameters (feed rate, cutting speed and depth of cut). Experimental procedure invovoles measuring the lengths of chips that slide on the tool face (tool-chip contact length) at various combinations of cutting parameters. Results indicate that as the resultant force increased from 583N to 2037N at constant depth of cut (0.10mm) and cutting speed (47m/min), the contact length increased from 0.08mm to 0.58mm for Aluminium alloys. At higher cutting speed of 71m/min and 0.20mm depth of cut, lower force of 594N to 1483N was recorded giving rise to increased contact length of 0.62mm to 0.86mm. Higher values of contact length (0.08mm to 0.74mm) are obtained for mild steel as the resultant force increased from 1079N to 3111N at the same cutting conditions for aluminium. At higher cutting speed of 71m/min and 0.20mm depth of cut, lower force of 854N to 2193N were obtained for mild steel with contact length increasing from 0.78mm to 0.95mm. Therefore, tool-chip contact length decreases as feed rate increases and mild steel gives higher cutting force in machining process than aluminium alloys under the same cutting conditions. Keywords: ; depth of cut; cutting speed; machining; contact length
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    Open Access
    The Inhibitory Influence of Artesunate on Myeloperoxidase Activity of the Polymorphonuclear Neutrophil
    (University of Lagos Press, Akoka, 2015) Minari, J.B; Oloyede, O.B; Odutuga, A.A
    Myeloperoxidase is the most abundant enzyme found in the polymorphonuclear neutrophil and is known to play a central role in the host defense system of the leukocyte. The enzyme has been reported to interact with some drugs to generate free radical which inhibits its activity. This study investigated the effects of artesunate on the activity of the enzyme. In investigating the effects of the drugs on myeloperoxidase, the influence of concentration, pH, partition ratio estimation and kinetics of inhibition were studied. This study showed that artesunate is concentration-dependent inhibitor of myeloperoxidase with an IC50 of 0.078 mM. Partition ratio estimation showed that 60 enzymatic turnover cycles are required for complete inhibition of myeloperoxidase in the presence of artesunate. The influence of pH on the effect of artesunate on the enzyme showed least activity of myeloperoxidase at physiological pH. The kinetic inhibition studies showed that artesunate competitively inhibited myeloperoxidase with an increase in the Km value from 0.12 mM to 0.26 mM and no effect on the Vmax value. The Ki value was estimated to be 2.5 mM. The results obtained from this study show that artesunate is a potent inhibitor of myeloperoxidase and it is capable of inactivating the enzyme. It is suggested that the inhibition of myeloperoxidase in the presence of artesunate as revealed in this study may partly explain the impairment of polymorphonuclear neutrophil and consequent reduction of the strength of the host defense system against secondary infections.
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    Open Access
    Reduction of Chemical Oxygen Demand and Potentially Toxic Metals in Leachates Generated from Isolo Dumpsite using Different Coagulants
    (University of Lagos Press, Akoka, 2015) Oluseyi, T.O; Hamed, M.O; Ibeh, K.I
    Leachate samples were collected from Isolo dumpsite within a seven month period, at eight different times after rainfall. The characterization of the leachate shows that they were sourced from an old landfill. The highest concentration of chemical oxygen demand (COD), biological oxygen demand (BOD) and total organic carbon (TOC) in the most polluted leachate samples were 392 mg/L, 203 mg/L and 5090 mg/L respectively. The levels of Fe, Pb, Cu and Zn were 19.7 mg/L, 2.06 mg/L, 2.18 mg/L and 3.50 mg/L respectively. Three different coagulants: ferric chloride, ferrous sulphate and aluminium sulphate were used to treat the most polluted leachate sample. Different pH and concentrations were investigated to obtain the optimal dosage for the most effective coagulant. The experimental results showed that at a neutral pH, 96% COD, 66.2% Fe, 94.3% Zn reductions were achieved at the lowest concentration of 1000 mg/L of Al2SO4.14H2O while FeCl3 and FeSO4 gave <96% reduction at a high concentration of 25,000 mg/L. The pH of 3, 5, 9 and 11 at optimal dosage of Al2SO4.14H2O gave 14%, 78%, 82%, 88% reduction of COD respectively. The result therefore indicates that Al2SO4.14H2O is the most effective of the three coagulants with optimal pH and dosage of 7 and 1000 mg/L respectively.