Strength Development in Lateritic Soil Stabilised with Coconut Shell Ash for Highway Pavement Construction

Lateritic soil has found wide usage in highway pavement construction in the tropics, however, there are instances that they are unsuitable because of their properties, hence the need for improvement through stabilisation. This research focussed on the utilisation of coconut shell ash for stabilising of lateritic soil for highway pavement construction. The lateritic soil was treated with 3 to 12% coconut shell ash (CSA) to assess its effect as a soil stabilising admixture on the geotechnical properties of the lateritic soil while the soil with 0% CSA is the control. The percentage passing sieve no. 200, liquid limit and plasticity index reduced with increase in the CSA content, this indicates that the susceptibility of the soil for water has been reduced. However, the maximum dry densities of the treated soil increased with increasing content of CSA but the strength index, California bearing ratio (CBR) decreased. Coconut shell ash though is a good pozzolan cannot therefore be used as a stand-alone stabilizer for treating lateritic soil however, the stabilized soil could be used as a subgrade foundation material in road pavement construction. Keywords: Coconut shell ash, Lateritic soil, Stabilization, Highway Pavement, Compaction, California bearing rati

Developmental Regulation of Genes Encoding Universal Stress Proteins in Schistosoma mansoni

The draft nuclear genome sequence of the snail-transmitted, dimorphic, parasitic, platyhelminth Schistosoma mansoni revealed eight genes encoding proteins that contain the Universal Stress Protein (USP) domain. Schistosoma mansoni is a causative agent of human schistosomiasis, a severe and debilitating Neglected Tropical Disease (NTD) of poverty, which is endemic in at least 76 countries. The availability of the genome sequences of Schistosoma species presents opportunities for bioinformatics and genomics analyses of associated gene families that could be targets for understanding schistosomiasis ecology, intervention, prevention and control. Proteins with the USP domain are known to provide bacteria, archaea, fungi, protists and plants with the ability to respond to diverse environmental stresses. In this research investigation, the functional annotations of the USP genes and predicted nucleotide and protein sequences were initially verified. Subsequently, sequence clusters and distinctive features of the sequences were determined. A total of twelve ligand binding sites were predicted based on alignment to the ATP-binding universal stress protein from Methanocaldococcus jannaschii. In addition, six USP sequences showed the presence of ATP-binding motif residues indicating that they may be regulated by ATP. Public domain gene expression data and RT-PCR assays confirmed that all the S. mansoni USP genes were transcribed in at least one of the developmental life cycle stages of the helminth. Six of these genes were up-regulated in the miracidium, a free-swimming stage that is critical for transmission to the snail intermediate host. It is possible that during the intra-snail stages, S. mansoni gene transcripts for universal stress proteins are low abundant and are induced to perform specialized functions triggered by environmental stressors such as oxidative stress due to hydrogen peroxide that is present in the snail hemocytes. This report serves to catalyze the formation of a network of researchers to understand the function and regulation of the universal stress proteins encoded in genomes of schistosomes and their snail intermediate hosts

Assessment of Water Quality Index and the Probable Human Health Implications of Consuming Packaged Groundwater from Abeokuta and Sagamu, Southwestern Nigeria

Background: Contamination of groundwater could result in serious and irreparable health problems for consumers. This study assessed the water quality and human health implications of metals in packaged groundwater from Abeokuta and Sagamu, southwestern Nigeria. Methods: One hundred and forty bags of the packaged groundwater were purchased and analyzed for physical and chemical parameters using standard procedures, while metals were determined using inductively coupled plasma optical emission spectrophotometry. Risk assessment of metals was estimated using hazard index (HI), hazard quotient (HQ), and cancer risk (CR). Water quality index (WQI) was also evaluated. Results: The observed physical and chemical parameters, except Mn and Fe, in the packaged groundwater samples were observed to be within the permissible limits of the World Health Organization. The WQI data indicated suitability for drinking purposes. The health risk data indicated high HQs > 1.0 for Ca (for adults and children at all the monitoring sites), Mn (children at all the sites, and adults at six sites), Mo (children at four sites, and adults at three sites), and Cu (children at three sites and adults at one site). Conclusion: The CRs of the packaged groundwater for Co and Ni at many sites revealed values > the acceptable limit of 1 × 10−4, indicating possible development of cancer by the consumers

Assessment of levels and health risk of Potentially Toxic Elements (PTEs) in selected sachet water packaged from groundwater resources in Ogun State, Nigeria

Background: Sachet water is a source of affordable drinking water for low-income socioeconomic class. However, contamination by potentially toxic elements (PTEs) could pose severe adverse health risk to consumers. Objective: The present study aimed at assessing the levels and health risk of PTEs in selected sachet water samples packaged from groundwater resources in Ogun State, Nigeria. Methods: A total of 140 bags of selected sachet water brands were purchased and analysed for eleven PTEs (some of which are rarely reported in Nigeria) using inductively coupled plasma - optical emission spectrophotometer. Recovery experiment was conducted to validate the performance of the used analytical instrument. Blank samples were also run to cancel the matrix effect of the analysing reagents, and to calculate the limit of detection. PTE data were evaluated for simple descriptive and inferential statistics using SPSS for Windows. Health risk assessment was conducted for hazard quotient (HQ), hazard index (HI) and cancer risk (CR). Results: Chromium (Cr) was the highest observed PTE in sachet water from Asero (707±1102 µg L−1), Isolu (363±374 µg L−1) and Makun-Shagamu (359±204 µg L−1) sites. The concentrations of Cr were higher than the permissible limit of the World Health Organization in 63% of the sachet water samples. Furthermore, the average contents of lead (Pb) and thallium (Tl) were observed at higher concentrations than the acceptable limits. The HQs exceeding the permissible threshold of 1.0 were observed for silver (Ag), aluminium (Al), arsenic (As), cadmium (Cd), Cr and Tl in 29% of the sachet water consumed by adults and children; indicating adverse health effects. The CRs of Cd and Cr at all the sampling locations, and As at few sites were higher than the acceptable limit of 1 × 10−4; suggesting possible development of cancer by the consumers. Conclusion: The high levels and health risk estimates of PTEs in the sachet water samples suggested unsafe for consumption. Periodic monitoring of PTEs in sachet water from the study area is recommended