Comparative study of Ikirun and Osogbo Slag on concrete grade 20

This study examined the use of Prism Steel Slag (PSS) and Machine Iron Slag (MIS) as partial replacement of coarse aggregate in concrete. Coarse aggregates were partially replaced with PSS and MIS at 0%, 10%, 20%, 30%, 40% and 50% respectively. A total of 132 concrete cubes of sizes 150 mm x 150 mm x 150 mm were cast and cured in water for 7, 14, 21 and 28 days respectively. Mix ratio of 1:2:4 was adopted with w/c ratio of 0.45 and batching was done by weight. The slump result indicated that the fresh concrete becomes stiff as the percentages of PSS and MIS increases. However, the compressive strengths of concrete cubes increased as the curing ages increases. 50% PSS and 40% MIS can successfully be used as partial replacement of coarse aggregate in the production of concrete grade 20.Keywords: Concrete, Coarse Aggregate, Strength, Machine Iron Slag, Prism Steel Sla

Abrasive Wear Resistance, Mechanical Behaviour, Water Transport Phenomena and Biocorrosion of Epoxy/Femora Biocomposites

Of late, some biological wastes have proven to be reliable candidates in promoting the economic viability of developing polymeric composites. However, the field-proven reliability prediction of such materials during service life requires extensive characterization. In this research, the influence of 75 µm bovine femur ash subjected to two-step calcination process on spectroscopic, wear, mechanical, water absorbent and biocorrosive properties of epoxy/femur waste biocomposites was investigated. The test materials were developed via open mould casting and subjected to preferred characterizations apropos of the abovementioned properties. Elemental constituents of the biocomposites and the ash were determined by energy dispersive x-ray spectroscopy with scanning electron microscopy and x-ray fluorescence spectroscopy, respectively. The investigated properties were studied dependent on predetermined volume fractions of the ash in epoxy matrix. Observations from the experimental results revealed that properties’ enhancement was not specific to either low or high volume fraction of the ash in epoxy. Different properties were enhanced at different volume fractions of the ash. Nonetheless, one biocomposite approaching intermediate volume faction of the ash used, exhibited optimum combination of the investigated properties. This is a clear indication that bovine femur waste can be successfully exploited for engineering applications, especially in the areas of materials development

Kontext, utvärdering och användarupplevelse : En studie om kontextens påverkan på användarnas respons vid utvärdering av användarupplevelse

In this paper we explore the relations between context and feedback generated in three user-centered evaluations of a flash-based game. Whether it’s the social context, the physical context or the degree of intrusion from the evaluator, they all contribute to the quality of the feedback received. The selection of test subjects is a narrow process, which gives the above mentioned factors different meaning. Contextual factors have shown to influence the feedback given within both usability and user-experience. The difference in feedback given to user-experience however, was shown to be influenced mostly by the social context where the selection of test-subjects and degree of involvement from the evaluator are key factors to the subjects. The test-subjects might not express vital thoughts because they don’t want to criticize the designer or intrude on the design, nor do they want to appear stupid when something is not understood

Abnormal biochemical parameters among term neonates with perinatal asphyxia and their non-asphyxiated controls in Osogbo

Objective: This study aimed to determine the prevalence of abnormal biochemical parameters among neonates with perinatal asphyxia in comparison to their non-asphyxiated controls.Methodology: This is a prospective case - control study involving 54 asphyxiated term neonates and 54 non-asphyxiated term babies at LAUTECH teaching hospital, Osogbo. Serum levels of Sodium, Bicarbonate, Chloride, Calcium and Potassium were determined daily for 72 hours in both groups using standard methods. The results were compared.Results: The overall prevalence of abnormal biochemical parameters namely hyponatraemia, hypocalcaemia, metabolic acidosis, hypochloraemia and hypokalaemia among the asphyxiated versus non-asphyxiated babies in the first 72 hours of life were 30.9% vs 19.8% (p < 0.020); 28.4% vs 4.9% (p < 0.000); 30.9% vs 3.1% (p < 0.0001); 27.2% vs 25.9% (p < 0.200) and 24.7% vs 3.1% (p < 0.070) respectively.Conclusion: Babies with hypoxic ischaemic encephalopathy stage III significantly showed the worst biochemical parameters; early estimation of serum electrolytes in neonates with perinatal asphyxia may be appropriate for timely intervention. &nbsp

GPS derived TEC and foF2 variability at an equatorial station and the performance of IRI-model

The ionosphere induces a time delay in transionospheric radio signals such as the Global Positioning System (GPS) signal. The Total Electron Content (TEC) is a key parameter in the mitigation of ionospheric effects on transionospheric signals. The delay in GPS signal induced by the ionosphere is proportional to TEC along the path from the GPS satellite to a receiver. The diurnal monthly and seasonal variations of ionospheric electron content were studied during the year 2010, a year of extreme solar minimum (F10.7 = 81 solar flux unit), with data from the GPS receiver and the Digisonde Portable Sounder (DPS) collocated at Ilorin (Geog. Lat. 8.50�N, Long. 4.50�E, dip �7.9�). The diurnal monthly variation shows steady increases in TEC and F2-layer critical frequency (foF2) from pre-dawn minimum to afternoon maximum and then decreases after sunset. TEC show significant seasonal variation during the daytime between 0900 and 1900 UT (LT = UT + 1 h) with a maximum during the March equinox (about 35 TECU) and minimum during the June solstice (about 24 TECU). The GPS-TEC and foF2 values reveal a weak seasonal anomaly and equinoctial asymmetry during the daytime. The variations observed find their explanations in the amount of solar radiation and neutral gas composition. The measured TEC and foF2 values were compared with last two versions of the International Reference Ionosphere (IRI-2007 and IRI-2012) model predictions using the NeQuick and CCIR (International Radio Consultative Committee) options respectively in the model. In general, the two models give foF2 close to the experimental values, whereas significant discrepancies are found in the predictions of TEC from the models especially during the daytime. The error in height dependent thickness parameter, daytime underestimation of equatorial drift and contributions of electrons from altitudes above 2000 km have been suggested as the possible causes