Models for predicting compressive strength and water absorption of laterite-quarry dust cement block using mixture experiment

The use of laterite, quarry dust and recycle aggregates etc as replacement for sand in sandcrete block production is common trend in developing countries like Nigeria. Most resources and research efforts are committed towards conducting trial test with a view to coming up with mix production that will yield the desired property. This work presents a mathematical model for predicting the compressive strength and water absorption of laterite-quarry dust cement block using augmented Scheffe's simplex lattice design. The statistical models developed can predict the mix proportion that will yield the desired property. The models were tested for lack of fit and found to be adequate.Keywords: compressive strength, laterite, mixture experiment, quarry dust, water absorptio

Influence of Rock Mineralogy on Subsurface Water in Ado-Ekiti, Nigeria

Sudden geometric increase in population of Ado-Ekiti has lead to an increase in demand for water and harnessing of subsurface water reserve. This research investigated the possible infiltration of dissolved mineral from weathered rock into subsurface water in the area (basement complex rocks), and comparing the mineral level with the set standard for quality water by the World Health Organization Physical test were carried out on hardness, colour, odour, conductivity, pH, and turbidity. Chemical test for sodium (Na+) and potassium (K2+) was also done using experimental scientific set standard. The analysis of the sodium, potassium ions, and the conductivity of the water indicate that dissolved mineral from rocks have great influence on the underground water property. The level of the dissolved mineral is within the acceptable limit for water quality standard set by the W.H.O. Sourcing for underground water should not be based on hydro geological variable alone but possible chemical interference from the geology of the environment (rock type).African Research Review Vol. 2 (2) 2008 pp. 175-18

Abandoned projects-implication on the strength of exposed steel and concrete in the Southern region of Nigeria

This research is centered on the investigation of the implication of abandonment on the strength of exposed steel and concrete in an abandoned project; as most abandoned project are continued without due consideration to the current strength of the structural members, which may lead to eventual collapse, if the structural members have failed in strength. Six abandoned project sites were investigated: three in Port Harcourt, Rivers state and the other three in Lagos, Lagos state, Nigeria. Thus limiting the investigation to Southern region of Nigeria where the temperature ranges between 23°C and 32°C and precipitation/rainfall ranged between 36mm and 410mm.The Periods of the abandonment ranges from three to thirty-five years. All structural members were cast in-situ. Visual inspections were carried out on site, rebound hammer test was done, concrete samples were cored and steel reinforcement bars were cut from site. Laboratory test and analysis were carried on te cored samples as well as tensile test carried out on the steel samples. Data obtained from both field and laboratory analysis, were analyzed using Excel regression analysis and a model was obtained to help determine the estimated steel strength of exposed steel reinforcement bars after a period of abandonment in the region considered.Keywords: abandonment, concrete, steel, compressive strength, tensile strengt

Environmental Cost Accounting and Cost Allocation (a Study of Selected Manufacturing Companies in Nigeria)

The major objective of this paper is to determine the extent to which Nigerian firms have embraced environmental cost accounting in cost allocation.  This research adopted a research survey and the main research instrument is the questionnaire. 105 Accountants from twenty-five (25) quoted manufacturing companies were the respondents for this research. The mean, standard deviation and simple percentages were used to analyze the questions while the ANOVA was used to statistically analyze the differences between means. Findings show that majority of the firms have not embraced environmental cost accounting, they still lump all indirect costs under overhead and use mostly, one absorption method which may not have any relationship with the indirect costs to apportion these costs into the product costs. The identified commonest method of overhead allocation basis is the material use. Although the treatments given to environmental costs were conventional in nature, significant differences exist among firms on the method of allocating environmental costs to products/processes. Environmental accounting can be said to be in embryonic stage in the manufacturing firms in Nigeria. This paper offers a valuable insight into the environmental cost accounting practices of Nigerian manufacturing firms. This paper will help firms to understand what environmental cost accounting is all about and how to embrace it. Keywords: Environmental accounting, Environmental cost accounting, environmental costs, conventional system

Relationship Between the Standard of Living, Economic Situation, and Security Situation of Nigerians During The Covid-19 Pandemic. A Non-Parametric Analysis Approach

The Covid-19 pandemic has crippled the economic activities of so many nations across the globe since its outbreak in 2019. This study is focused on the resultant effect of the covid-19 pandemic in terms of standard of living, perception of economic and security situation of Nigerians. This study used a non-parametric approach involving Spearman rank correlation and Mann-Whitney U to analyze primary data acquired from NoiPolls’ online administration of questionnaires during the Covid-19. The result obtained from this study depicts that there is a significant relationship between the security situation and perception of the country’s economic situation. The standard of living of Nigerians was studied alongside their perception of the economic situation and we observed that there is a significant relationship between these two. This was also examined based on gender, the Mann-Whitney U test was used to check if there exists any form of difference between males and females based on the security situation, economic perception, and standard of living. The test result showed that there is no significant difference in the standard of living of both males and females but significant differences were observed in the economic perception and security situations. A bar chart was further used to visually assess these differences where it is seen that females feel more secure compared to males and females feel less satisfied with the country’s economic situation compared to the males

Mathematical Modelling of Compressive Strength of Recycled Ceramic Tile Aggregate Concrete Using Modified Regression Theory

At present, the large quantity of wastes generated by the ceramic industry is not reused in any significant quantity. Research has shown the feasibility of incorporating these wastes into concrete production. This will benefit both the ceramic and concrete industries. However, not much research data is available on the use of ceramic wastes as fine aggregate material compared to their use as coarse aggregate material. Moreover, there are presently no models for predicting the properties of ceramic waste aggregate concretes. In this study, a modified regression theory based on Taylor’s series was adopted to formulate mathematical model for predicting compressive strength of concrete into which Recycled Ceramic Tile (RCT) is incorporated as fine aggregate.  Preliminary tests on RCT indicate that it is a suitable fine aggregate material for concrete production. It has also been established that addition of RCT improves compressive strength of concrete and reduces concrete’s workability. The formulated model is a function of the mix proportions of its constituents and its predicted responses are in good agreement with experimentally observed data. The model has been tested using student’s t-test and analysis of variance and has been confirmed to be adequate and hence is validated

Mathematical model to predict split tensile strength of concretes in crude oil contaminated environments

Few concrete components used for constructions within the Niger Delta region of Nigeria are contaminated with crude oil to varying ranges. An investigation into the split tensile behaviour of concretes to crude oil when cured in 10% crude oil/water medium is carried out in this work. In this work, crude oil was used as a fifth ingredient of concrete mix which replaced 5% to 20% of the w/c. The four other components were cement, sand, granite, and water. A designed mix ratio of 1:2:4 with w/c of 0.5 was utilized as the initial component mix design. Scheffe’s simplex theory was used for the five mix ratios in a {5,2} experimental design. This gave rise to ten additional mix ratios and fifteen other additional mix ratios were generated for control purposes. These thirty concrete mix ratios were subjected to laboratory experiments to determine the 7 and 28 days split tensile strengths. The results of the first fifteen split tensile strengths were used for the calibration of the model constant coefficients, while the results from the second fifteen were used as control. A mathematical regression model was derived from the results, with which the split tensile strengths were developed. The derived model was subjected to a two-tailed t-test with 5% significance, which ascertained the model to be adequate with an R2 value of 0.9616 and 0.9227. The study revealed that crude oil presence in a concrete mix can be harmful as it reduces the split tensile strength of concretes

Solenostemon monostachyus Modulates Inducible Nitric Oxide Synthase and mRNA Expression in Hemolytic-Induced Rats

Background and Objective: The 2-Butoxyethanol (2BE) rat model of human hemolytic disorders has been used widely to evaluate hemolysis and thromboembolic manifestations of different organs associated with sickle cell disease and $-thalassemia, however, studies on nitric oxide metabolism are far more scarce. This study investigated the effects of Solenostemon monostachyus leaf extract supplementation on 2BE-induced changes of inducible nitric oxide synthase (iNOS) levels and mRNA expression in female rats. Materials and Methods: Young female rats were divided into seven groups (Group A-G). All groups, except for group A, were exposed to 2BE. The treatments assignments were as follows, group C: Caffeic acid, group D: Ciklavit (herbal formulation of Cajanus cajan (L.) Mill sp.), group E-G: S. monostachyus (150, 200 and 250 mg kgG1 b.wt.), respectively. Liver and plasma iNOS levels, as well as mRNA expression of liver arginase-1 and iNOS, were assessed. Histopathological evaluation of the liver was also performed. The results were statistically analyzed for significant effects at p<0.05 using one-way analysis of variance (ANOVA). Results: Liver and plasma iNOS were significantly reduced (p<0.05) in group G, whereas liver iNOS was significantly increased (p<0.05) in group D-F compared with group B, iNOS mRNA expression was reduced, while arginase-1 mRNA expression was increased in group E-G compared with group B. Conclusion: Administration of S. monostachyus (250 mg kgG1 b.wt.) in the 2BE hemolytic rat model modulated plasma and liver iNOS levels and iNOS mRNA expression

Pattern and Determinants of Antiretroviral Drug Adherence among Nigerian Pregnant Women

Background. The need for a high level of adherence to antiretroviral drugs has remained a major hurdle to achieving maximal benefit from its use in pregnancy. This study was designed to determine the level of adherence and identify factors that influence adherence during pregnancy. Method. This is a cross-sectional study utilizing a semistructured questionnaire. Bivariate and multiple logistic regression models were used to determine factors independently associated with good drug adherence during pregnancy. Result. 137 (80.6%) of the interviewed 170 women achieved adherence level of ≥95% using 3 day recall. The desire to protect the unborn child was the greatest motivation (51.8%) for good adherence. Fear of being identified as HIV positive (63.6%) was the most common reason for nonadherence. Marital status, disclosure of HIV status, good knowledge of ART, and having a treatment supporter were found to be significantly associated with good adherence at bivariate analysis. However, after controlling for confounders, only HIV status disclosure and having a treatment partner retained their association with good adherence. Conclusion. Disclosure of HIV status and having treatment support are associated with good adherence. Maternal desire to protect the child was the greatest motivator for adherence

Relationship Between the Standard of Living, Economic Situation, and Security Situation of Nigerians During The Covid-19 Pandemic. A Non-Parametric Analysis Approach

The Covid-19 pandemic has crippled the economic activities of so many nations across the globe since its outbreak in 2019. This study is focused on the resultant effect of the covid-19 pandemic in terms of standard of living, perception of economic and security situation of Nigerians. This study used a non-parametric approach involving Spearman rank correlation and Mann-Whitney U to analyze primary data acquired from NoiPolls’ online administration of questionnaires during the Covid-19. The result obtained from this study depicts that there is a significant relationship between the security situation and perception of the country’s economic situation. The standard of living of Nigerians was studied alongside their perception of the economic situation and we observed that there is a significant relationship between these two. This was also examined based on gender, the Mann-Whitney U test was used to check if there exists any form of difference between males and females based on the security situation, economic perception, and standard of living. The test result showed that there is no significant difference in the standard of living of both males and females but significant differences were observed in the economic perception and security situations. A bar chart was further used to visually assess these differences where it is seen that females feel more secure compared to males and females feel less satisfied with the country’s economic situation compared to the males