CLASSICAL OPTIMIZATION OF BAGASSE ASH CONTENT IN CEMENT-STABILIZED LATERITIC SOIL

Optimization of construction materials with laboratory data is a very possible way of minimizing waste of resources (materials and cost). There had been several successful attempts of optimization of construction materials. However, optimization in soil stabilization for road-work has been very rare because of its complexities. Compaction, California bearing ratio, unconfined compressive strength and durability tests were carried out on cement-stabilized soil. Constant cement contents of 2%, 4%, 6% and 8% with variations of bagasse ash from 0% to 20% at 2% intervals and all percentages used were by the weight of dry soil.  The classical method was applied in this work to optimize the amount of bagasse ash content in cement-stabilized lateritic soil. Geometric models that govern the relationships of cost of bagasse ash content, cement content, optimum moisture content and strength characteristics of the stabilized-soil matrix were used to develop non-linear programming model. Then it was linearized and solved using the simplex method with sensitivity analysis. The optimal solution at the desired unconfined compressive strength and California bearing ratio for sub-base of road-work for bagasse ash content, cement content and optimum moisture content were found to be 14.03%, 4.52% and 22.46% respectively. Optimzation and the use of bagasse ash gave a cost benefit of 9.24% with a better mix. The classical optimization technique appears to be suitable in soil stabilization. http://dx.doi.org/10.4314/njt.v35i3.

Geometric models for lateritic soil stabilized with cement and bagasse ash

Agricultural and environmental demands for natural aggregates coupled with frequent increases in the price of cement and other binders have consequently escalated the cost of construction, rehabilitation and maintenance of road works. Soil stabilization emerges as an attractive option for providing low-cost roads. Bagasse-ash is an agricultural material obtained after squeezing out the sweet juice in sugarcane and incinerating the fibrous residue to ash. This residue that would have constituted an environmental problem during disposal and handling could be used as a supplement or partial replacement for cement in the cement-bound soil when converted to ash. Thus this study attempted to investigate into the effects of bagasse ash on compaction and strength characteristics of cement-stabilized lateritic soil and also to develop geometric models. The compaction, California bearing ratio, unconfined compressive strength and durability tests were carried out on the cement-stabilized soil. Constant cement contents of 2%, 4%, 6% and 8% with variations of bagasse ash from 0% to 20% at 2% intervals and all percentages used were by the weight of dry soil. The multiple regression and the least square approach was used to develop geometric equations which was made less rigorous with Minitab statistical software. The three geometric equations developed covered the relationships of cost of bagasse ash content, optimum moisture content, cement content, California bearing ratio and unconfined compressive strength at 7 days. It was observed that optimum moisture content increased progressively while maximum dry density reduced with increase in bagasse ash content. Also the increase in cement content increased both the optimum moisture content and maximum dry density. In addition, all the strength properties were increased with increase in bagasse ash content and chemistry responsible was also presented. Thus bagasse ash was confirmed to be a good admixture in soil stabilization for road-work. The models were calibrated and verified; and were found to be dependable. http://dx.doi.org/10.4314/njt.v35i4.1

Principal Component Regression Analysis of CO2 Emission

Principal component regression (PCR) model is developed, in this study, for predicting and forecasting the abundance of CO2 emission which is the most important greenhouse gas in the atmosphere that contributes to global warming. The model was compared with supervised principal component regression (SPCR) model and was found to have more predictive power than it using the values of Akaike information criterion (AIC) and Swartz information criterion (SIC) of the models.Keywords: Global warming, CO2, Principal component regression (PCR), Supervised principal component regression (SPCR), Akaike information criterion (AIC) and Swartz information criterion (SIC

Inter-Relationships Between Yield And Yield Attributes Of Potato Grown Under Supra-Optimal Ambient Temperatures

Forty eight potato genotypes were evaluated in Saminaka (Lat. 100 27’N and Long 40E, Mean Min. Temp 25oC, Mean Max Temp 31.5oC) during the rainy season of 1999 and 2000 to determine the inter-relationship between yield and some important agronomic traits in the potato grown under high ambient temperatures. The genotypes were laid out in a randomized complete block design with three replications. The genotypes exhibited highly significant variability (

Serum Levels of Pro-inflammatory Cytokines in relationship to outcomes in Children with P. falciparum malaria, in Nnewi-South east Nigeria

Background and Objective: In P. falciparum malaria (PFM) infestation there are marked changes in cytokine production as the body mounts an immune response to it. Hence we set out to study these changes.Methods: A total of 158 cases of PFM among children attending the paediatric unit of our hospital and 56 healthy controls were studied. Children with febrile illness were screened for malaria using 10% Giemsa stained blood smear. Patients with positive smears were recruited; co-infected patients – those infected by another organism in addition to plasmodium specie.- were excluded. Whole blood was collected, some into plain tubes for serum cytokine testing and some into EDTA bottles for complete blood count and parasite density (PD) determination. Controls with asymptomatic parasitaemia were excluded.Results: Using the World Health Organization criteria for defining severe malaria; we identified 15 cases of severe and 143 cases of uncomplicated PFM. Significantly elevated levels of interleukin-1 (IL-1), interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-α) were seen in the uncomplicated and severe forms of PFM. It was observed that the elevated cytokine values correlated with PD (in uncomplicated PFM but not in the severe forms). The difference between PD/absolute monocyte count (AMC) ratio was not significant (p=0.13); while PD/platelet count (PC) and PC/ AMC ratios were significant (p=0.01, and 0.03 respectively) when compared between uncomplicated and severe disease.Conclusion: Our data seems to suggest that subjects with an adequate immune response to the parasite density, in terms of pro-inflammatory cytokine levels, presented with uncomplicated disease; while those who have an inadequate response presented with severe disease. The ratios of (PD/PC) and (PC/AMC), in the positive and negative directions respectively, may be predictors of increased disease severity. These observations may have implications for predicting disease outcome and PFM therapy.Key Words: plasmodium falciparum malaria, pro-inflammatory cytokines, Parasite density/Platelet count ratio, Platelet count/Absolute monocyt

Plasma phosphorylated-tau181 as a predictive biomarker for Alzheimer’s amyloid, tau and FDG PET status

Plasma phosphorylated-tau181 (p-tau181) showed the potential for Alzheimer’s diagnosis and prognosis, but its role in detecting cerebral pathologies is unclear. We aimed to evaluate whether it could serve as a marker for Alzheimer’s pathology in the brain. A total of 1189 participants with plasma p-tau181 and PET data of amyloid, tau or FDG PET were included from ADNI. Cross-sectional relationships of plasma p-tau181 with PET biomarkers were tested. Longitudinally, we further investigated whether different p-tau181 levels at baseline predicted different progression of Alzheimer’s pathological changes in the brain. We found plasma p-tau181 significantly correlated with brain amyloid (Spearman ρ = 0.45, P 18.85 pg/ml) at baseline had a higher risk of pathological progression in brain amyloid (HR: 2.32, 95%CI 1.32–4.08) and FDG PET (3.21, 95%CI 2.06–5.01) status. Plasma p-tau181 may be a sensitive screening test for detecting brain pathologies, and serve as a predictive biomarker for Alzheimer’s pathophysiology

Perceptions and utilization of the anti-malarials artemether-lumefantrine and dihydroartemisinin-piperaquine in young children in the Chikhwawa District of Malawi: a mixed methods study

Background Adherence to anti-malarial dosing schedules is essential to ensure effective treatment. Measuring adherence is challenging due to recall issues and the participants’ awareness of the desired behaviour influencing their actions or responses. This study used qualitative methods, which allow for rapport building, to explore issues around anti-malarial utilization in young children, and used the results to guide the development of a context specific questionnaire on perceptions and adherence to artemether-lumefantrine (AL) and dihydroartemisinin-piperaquine (DHA-PPQ). Methods Qualitative data collection included 12 focus group discussions which explored community perceptions of anti-malarials and experiences of administering medications to children. Critical incidence interviews were conducted with 22 caregivers to explore experiences of administering the dispersible or original formulation of AL to young children during recent febrile episodes. A structured questionnaire was used to gather data on experience of recent treatment and adherence to anti-malarials during follow-up visits with 218 caregivers whose child was recently treated with either dispersible AL or DHA-PPQ. Discussion/Conclusion Caregivers experience great difficulty in administering medication to children. While the sweet taste of dispersible AL may have reduced conflict between the child and caregiver, sub-optimal dosing due to medication loss remained a problem and overall adherence was greater among those receiving DHA-PPQ, which requires fewer doses. Some caregivers were found to deliberately alter the dosing schedule according to whether they perceived the medication to be too weak or strong. They also developed theories for poor treatment outcomes, such as attributing this to lack of compatibility between the medication and the child. Health education messages should be strengthened to ensure a combination of clear pictorial and verbal instructions are used during dispensing, and consequences of under and over-dosing are explained alongside appropriate responses to possible adverse events. Further optimizing of anti-malarial adherence among children requires the development of anti-malarials with pharmacological properties that allow user-friendly administration and simplified dosing schedules