Suitability of local binder compositional variation on silica sand for foundry core-making

The use of local oils, namely groundnut oil, cotton seed oil and palm oil with Nigeria local clay and silica sand for the production of foundry cores has been investigated on varying composition. Addition of cassava starch, local clay, oil and moisture to sand are used to produce strong and efficient core. These oils were tested and it was found that the three could be used to produce foundry cores. The best composition was found to be core comprising 2.5% starch, 2.5% clay, 8% oil, 8% moisture and 68% sand and baked at 150oC for 1 h 30min. The tensile strength of the core were as high as 600 KN/m2

Assessment of geomorphic and morphometry characteristics of parts of Shasha and Opa river basins in Obafemi Awolowo University Campus, Southwestern Nigeria

Geomorphic and morphometry characteristics of parts of Shasha and Opa Basins in Obafemi Awolowo University campus, Ile-Ife, southwestern Nigeria were assessed through the analysis of basin linear, areal and shape parameters with a view to quantitatively describe the hydrological characteristics of the area. The campus is drained by Rivers Shasha and Opa and their tributaries. Stream order, stream number, stream length, mean stream length, stream length ratio, length of over land flow, confluence factor, form factor, elongation ratio, stream segment density, drainage density, drainage texture and slope within the campus were determined through the evaluation of topographic, drainage, and land use and land cover maps. The campus is drained mostly by River Opa (4th order channel) and its tributaries while the remaining part (i.e. northeastern and northwestern parts of the campus) is drained by River Shasha (3rd order channel) and its tributaries. The mean 1st, 2nd and 3rd stream orders of River Shasha were 0.42, 0.54 and 1.03 km, respectively; while the mean stream length for the 1st , 2nd , 3rd and 4th stream orders of River Opa were 0.40, 0.64, 1.84 and 4.07 km, respectively. The average length of overland flow within the Shasha sub-basin was 0.25 km, while the average - length of overland flow within the Opa sub-basin was 0.15 km. Stream segment density increased from 0.16 km to 3.18 km in River Shasha and 0.08 km to 4.33 km in River Opa. Increased stream segment density from lower to higher stream order could have been influenced by increased fracture control of streams from lower to higher stream order. The predominant trend of the streams were NE-SW and NW-SE, suggesting the influence of differing lithologies or tectonic activities, where streams must have developed by taking advantage of the local relief for the varying stream flow directions

MATERIAL PERFORMANCE INVESTIGATION ON THE FAILURE OF AN AIRCRAFT (ABT-18) NOSE WHEEL STRUT

The study investigated the cause and mechanism of failure of the nose wheel strut of a trainer aircraft with respect to material selection.Various methods and tests ranging from visual examination via unaided eye and fractography, hardness tests, chemical analysis and microstructural examination were employed for the study. The results show chevrons on the fracture surface which indicates fatigue failure characteristic of brittle fracture. Also, thefractographshowsincidence of a ductile pull and high energy fracture.This is evident by the cone shape of the fractograph and the observed tear.Hardness tests results showed high discrepancy between the values of the failed and undamaged samples indicating loss of strength and ductility in the failed sample as a result of fatigue. The outcomeof chemical analysis revealed that the component is made from medium carbon steel of the tough grade instead of the required spring steel.Therefore, a major cause of the failurecan be linked to improper material specification for the nose wheel strut.The failure mechanism was further confirmed by microstructural examination which revealed fatigue cracks propagated from inclusions in the microstructure of the failed sampl

Influence of Plating Parameter and Surface Morphology on Mild Steel

The plating parameter effect of zinc deposition on mild steel substrates was investigated. The results showed an improved surface finished and homogeneous layer. The distance between the anode and the cathode on voltage, plating time and coating thickness were considered. The mild steel was deposited into solution of zinc bath for varying voltage between 0.5 v and 1.0v. It was discovered that the sample plated at 0.8v for 15 minutes gives the best plating deposition and appearance. The surface morphology of the plated sample was analyzed by Focused ion beam scanning electron microscopy (FIB-SEM), AFM and X-ray diffraction

Literal Level of Student's Comprehension in Nigeria: A Means for Growing a New Generation African Scholars

The concern of this study was to examine students’ attainment in literal level of reading comprehension under reading for exact meaning, for information and for gist in a text. Two research questions and two hypotheses were formulated to guide in the study. An expost-facto research design was also employed. The researcher used an adapted Literal Reading Comprehension Test (LRCAT) for data collection. Out of a population of 1,803 SS2 students in Uyo L.G.A, 109 students formed the sample by  a stratified and  a hart and draw simple random sampling technique. Data collected were analyzed using the mean, standard deviation and paired dependent t-test.The mean score of students in reading for exact meaning was higher than reading for information and gist. The major findings were that with a df of 108 there is significant difference in students’ mean attainment scores in reading for exact meaning and reading for information. Also, there is significant difference in students’ mean attainment scores of reading for exact meaning and reading for gist. Based on the findings, it was recommended among others that, learners should consciously be taught how to develop their literal reading comprehension in order to encourage the acquisition of other comprehension levels at the senior secondary level, if  comprehension must have been attained. Keywords: Literal Reading Comprehension, Reading for Gist, Reading for Informatio

Malocclusion and occlusal traits among orthodontic patients seen at the University of Benin Teaching Hospital, Nigeria

Objective: The aim of this study was to determine the prevalence and trend of malocclusion and occlusal traits among orthodontic patients in Benin City. Method: One hundred and thirty one patients, consisting of 71 females (54.2%) and 60 males (45.8%) aged 5 - 44 years (mean 17.9 ± 7.5 years) who presented for orthodontic treatment at the University of Benin Teaching Hospital Dental Centre were assessed for sagittal molar occlusion, overjet, overbite, crossbite, open bite, crowding, spacing, median diastema, midline shift, malformed and supernumerary teeth, displaced, unerupted and impacted teeth. Statistical gender differences in the occlusal traits were evaluated with the chi-square test. Result: The results revealed high prevalence of Angle\u27s class I malocclusion (71.8%), while 9.9% of the subjects had Angle\u27s Class II division 1, 7.6% had Angle\u27s Class II division 2 and 10.7% had Angle\u27s class III malocclusion. An increased overjet greater than 3.5mm was observed in 43% while increased overbite was observed in 25.2%. Anterior open bite was seen in 8.4% while 21.4% and 12.2% had anterior and posterior crossbites respectively. Midline shift was present in 29.8%, crowding of both upper and lower anterior segments was observed in 47.3%, spacing in the upper and lower anterior segments was present in 22.1%, and midline diastema was observed in 21.4%. No statistically significant gender differences were observed for any of the occlusal variables evaluated (P>0.05). Conclusion: This study revealed high prevalence of class I malocclusion, increased overjet and crowding among the orthodontic patients seen in Benin City, Nigeria

Degradation Evaluation of Zinc m 2 M Hydrochloric Acid m the Presence of Bambusa bambos

Failure evaluation of zinc sample in 2 M hydrochloric acid solution in the presence of Bambusa bambos extract was conducted using the gasometric method. Zinc coupons, each measuring 2.5 by 1.5 em were completely immersed in uninhibited and inhibited test solutions containing extract quantities of 60, 100 140 and 180 mL at a temperature of 298 K for 20 minutes. The volumes of hydrogen gas data obtained during the experiment were documented and analyzed. Results showed that maximum inhibitor efficiency and lowest corrosion rate were obtained at extract quantities of 140 and 100 mL, respectively while corrosion rate reduction did not follow any particular trend. Frumkin isotherm best explained the extract-metal surface interaction adsorption mechanism. Once quantity of the extract is known, an expression for estimating corrosion rate values was also obtained. In addition, the surface analysis indicated that the rate of deterioration of the metal reduced as extract quantity increased to some extent and changed thereafter

Regulatory mutations affecting the synthesis of cellulase in Pseudomonas fluorescens

Pseudomonas fluorescens, was cultured in basal medium containing carboxymethyl-cellulose (CMC) as inducer and glucose or glycerol as carbon and energy sources. Ethylmethanesulphonate (EMS) was used to mutagenize the wild-type organism to produce mutants. The isolated mutants were screened for the isolation of catabolite repression resistant mutants in the presence of 1% (w/v) glucose as carbon source. A total of fifty mutants were isolated. All the mutants produced cellulase in the presence of CMC as an inducer with specific activity of 0.057, 0.088 and 0.074 units/mg protein for the wild-type, catabolite repression resistant mutant4 (CRRmt4) and catabolite repression resistant mutant24 (CRRmt24), respectively. It was observed that addition of glucose or glycerol as carbon and energy sources to the culture medium resulted into considerable reduction in the cellulolytic activity. However, glycerol appeared to be a better carbon and energy source than glucose which inhibited enzyme expression in most of the strains used in this study. It was also observed that potent cellulase production occurred at the exponential growth phase of the organism. The isolated mutants were grouped into three classes based on their induction ratios namely; unimproved mutants, catabolite repression resistant mutants and mutants with highest induction ratio but sensitive to catabolite repression in the presence of high glucose concentration. The overall results obtained showed that cellulolytic activity in P. fluorescens was regulated by catabolite repression.Key words: Pseudomonas fluorescens, ethylmethanesulphonate, mutants, cellulose, catabolite repression, induction ratio.African Journal of Biotechnology Vol. 4 (8), pp. 838-84

Performance Evaluation and Multidoped Composite Conditioned of A5-type/10%Ti-Sn Alloy: Processing and Properties

The need to improve the mechanical and electrochemical performance of aluminum alloy for extended application is the motivation behind this present work which is the inoculation of TiO2/SnO2 composite particulates on A500 by stir casting route. The effect of Ti/Sn on A500 aluminum series on the properties and microstructure of the produced alloy were investigated. The TiO2/SnO2 was varied from 5 to 10 wt.%. The microstructural properties of these sequence alloys were investigated using scanning electron microscopy coupled with energy dispersive spectroscopy, and X-ray diffraction. The corrosion degradation properties in 3.65% NaCl solution were studied using linear potentiodynamic polarization technique. The wear and hardness of the composite-induced aluminum alloy were measured with dry abrasive MTR-300 testers and high diamond microhardness tester, respectively. The results showed that the average hardness value of 42.56 and 65.5 HV and wear loss of 1.5 and 0.5 g were obtained for the 0% and 10 wt.% TiO2/SnO2 in A500 series. Hence, the addition of TiO2�SnO2 led to the precipitation and modification of complex intermetallic particles like Al2SnTiO and AlSiSn which also indicate a fairly good interfacial interaction. This outcome has established that up to 10 wt.% particulate on A500 aluminum can be used in enhancing the tribology

Assessing the deterioration behaviour of mild steel in 2 M sulphuric acid using Bambusa glauscescens

The study investigated the deterioration of mild steel in 2 M sulphuric acid solution in the presence of Bambusa glauscescens extract using gasometric technique. Steel coupons measuring 4 cm by 1.5 cm were immersed in test solutions of uninhibited acid and also those containing extract concentrations of 60,100 and 140 cm3 at a temperature of 333K for 60 minutes. The volumes of hydrogen gas evolved from the reaction were documented and analyzed. The analysis showed that while extract concentration was increasing, H2 evolution and % I.E increased. There was also a corresponding reduction in corrosion rate as extract concentration increased. The decrease in corrosion rate was observed to follow in order of increasing extract concentration. Phytochemical-metal interaction mechanism was best described by Freundlich isotherm, with the 4 and 12 minutes curve becoming the best and worst contact time for the extract phytochemicals to suitably adsorb to metal surface for all concentrations used. An expression suitable for calculating corrosion rate values once concentration is known was also deduced. Furthermore, the microstructural studies revealed that increasing the extract concentration resulted in significant reduction in the dominant coarsening of the oxide of iron phase, while the pearlite and ferrite phases became finely disperse