Properties of groundnut shell (Arachis hypogaea) ash blended portland cement

The study of the properties of groundnut shell ash (GSA) obtained at 500oC revealed that the ash is a pozzolanic material. Its pozzolanicity was studied by Chemical analysis test conducted with the aid of Minipal 4 Energy Dispensing X-ray Fluorescence Spectrometer (EDXRF) as well other physical tests conducted on the material. Hydration behavior of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14% and 16% by weight of GSA blended ordinary Portland cement (OPC) was studied through workability measurement, setting time measurement and compressive strength measurement; it was found that at 28 days of hydration the compressive strength value for 12 wt% GSA blended cement concrete was quite comparable to that of concrete made from OPC. However, the highest compressive strength was obtained at 4 wt% GSA replacement with OPC. Chloride Ion penetration of OPC, OPC with 4% GSA and OPC with 12% GSA were then determined using Rapid Migration test. The result showed that application of 12% GSA blended OPC cement in concrete increases the resistance of such concrete to chloride ion penetration.Keywords: Groundnut shell ash, Rapid migration test, chloride ion penetration, compressive strengt

Crystal and microstructure analysis of Pozzolanic properties of bamboo leaf ash and locust beans pod ash blended cement concrete

Pozzolans have been discovered recently to be of various benefits to the  construction industries and various researches are on the high gear to further discover, proof and established their suitability as substitute to cement. This research work has therefore work on the effectiveness of bamboo leaf ash (BLA) and locust beans pod ash (LPBA) as pozzolans with reference to crystal and microstructure of its hydrated paste. Ordinary Portland cement was partially  replaced with BLA and LPBA at different percentages, concrete pastes were made and cured at 7 and 28 days for the tests. The research work has been carried out using compressive strength test, X-ray fluorescence spectrometer, X-ray diffraction analysis as well as scanning electron microscopy to discover, present and analyze the quality and quantity of composition and hydration behavior of the different paste. The tests established BLA and LBPA as capable of successfully replacing cement in concrete production with added advantages in the properties of such concrete in term of mineral composition and microstructure  interlocking.Keywords: Concrete, pozzolans, microstructure, crystal, hydration, silica ©JASE

Surface composites and functionalisation : enhancement of aluminium alloy 7075-T651 via friction stir processing

Abstract: This research work is aimed at modifying and enhancing the properties of aluminium alloy 7075- T651 through the friction stir processing (FSP) technique, in order to improve the mechanical, electrochemical, structural, tribological as well as the metallurgical properties which include micro- and macro- structural analysis through XRD and Image processing of grain size and grain flow patterns determination, by reinforcing the parent metal. The surface modification of the parent metal has been made possible in the past via different techniques,such as laser surfacing, electronbeam welding and thermal spraying; but in recent years, the friction stir processing (FSP) technology has been adopted to cater for the complex methods of surface enhancement. FSP is well-renowned for its short route of fabrication, densification, grain refinement, homogenization of the precipitates of composite substances, nugget zone homogeneity. These have led to the efficient surface enhancement, significant and remarkable improvement in hardness, ductility, strength, increased fatigue life, as well as formability within which the bulk properties are still intact. The use of FSP in the fabrication of metal matrix composites (MMCs), especially aluminium matrix composites (AMCs) and aluminium hybrid composites (AHCs) were dealt with in this study...Ph.D. (Mechanical Engineering

Molecular Approaches in the Diagnosis of Diarrhoeal Disease in Children from Rural Gambia

Enteroaggregative Escherichia coli (EAEC) is a genetically diverse enteric pathogen that causes growth faltering among children, acute and chronic diarrhoea among children and adults living in both industrialised and low income countries. The German outbreak of EAEC-Shiga-toxin-E. coli in 2011 resulted in over 4000 confirmed cases of diarrhoea with over 54 fatalities in 14 European countries as well as United State of America and Canada. Several studies conducted in sub-Sahara Africa (SSA), Latin America and Asia countries have identified EAEC more frequently than any other bacterial pathogens. In SSA, case fatality due to EAEC is not well documented but the morbidity rate particularly among younger children is huge. Studies conducted in Senegal, Central-Africa-Republic and Tanzania showed that EAEC were endemic among HIV-positive patients with diarrhoea. Few studies from SSA have reported distribution of antimicrobial resistance pattern of EAEC. The Global Enteric Multisite Study (GEMS), a three-year case-control study conducted in seven African and Asia countries, showed that the prevalence of EAEC was higher among children with no diarrhoea (463/741, 62.5%) compared to children with diarrhoea (278/741, 37.5%). The aim of this retrospective analytical study nested to GEMS is to explore other molecular approaches that identify infectious EAEC and to show the genetic diversity and antimicrobial resistant pattern of EAEC. Study design of the first approach involves unmatched case-control 428 (157 cases and 271 controls) EAEC isolates that were examined by polymerase chain reaction (PCR) for the presence of 21 common EAEC virulence genes. This investigation implicated plasmid-encoded toxin (pet), AAF/1 fimbrial subunit (aggA) and hexosyltransferase homolog (capU) to be associated with diarrhoea in infants. In addition, two other virulence genes; Shigella exracellular protease A (sepA) and EAEC-heat-stable enterotoxin 1 (EAST1) were implicated in the EAEC that cause diarrhoea among children under 5 years old. The second approach utilised qualitative PCR (TaqMan-qPCR) method to assess the use of bacterial load diagnostic tool to diagnose infectious EAEC on selected matched case-control 160 (80 cases and 80 controls) EAEC isolates. Two biomarker genes, aatA and aaiC were the target in this study and both resulted in higher rate of higher bacterial load in controls (58/80 [72.5%]) compared to cases 48/80 [60%]), p – value 0.096. The third approach explored bacterial biofilm formation to diagnose infectious EAEC on 400 unmatched cases (150) and controls (250) EAEC isolates. Infectious EAEC produces biofilm to consolidate its colonisation in the host and damage to the tissue. The result of this study showed higher proportion of biofilm-producing EAEC in controls (61%) compared to cases (39%). However, biofilm-producing EAEC isolates that has aggR gene combined with one or all of the following virulence genes aatA, Aap, Orf3 and Orf61 revealed strong association with diarrhoea. Investigation into the antimicrobial resistant EAEC on the same 400 unmatched EAEC isolates revealed multi-drug resistant (MDR) EAEC infection as a significant problem among infants in the Gambia. MDR EAEC strains are almost equally distributed among cases and controls, and high (>71%) rate of resistant to Ampicillin, Sulphamethoxazole-trimethoprim and Tetracycline, and moderate (25%) rate of resistant to Chloramphenicol among study children. However, over ninety-four percent of the Gambia EAEC strains are susceptible to Cefotaxime, Ceftazidime, Ceftriaxone, Ciprofloxacin, Gentamicin and Amoxicillin-clavulanic acid. Additionally, result of whole genome sequencing (WGS) on 50 randomly selected EAEC isolates showed average 94% concordance of resistance genes with phenotypic disc diffusion method. This thesis provides detailed initial description and exploration of virulence genes associated with EAEC strains circulating in the rural Gambia and has revealed the likely biomarker genes to target in the diagnosis of infectious EAEC that cause diarrhoea in infant

Experimental and numerical prediction of extrusion load at different lubricating conditions of aluminium 6063 alloy in backward cup extrusion

In the present research work using a backward cup extrusion (BCE) die profile, different lubricating conditions on aluminum alloy AA6063 have been experimentally and numerically investigated to predict the extrusion load. It was obvious that due to an increase in applications of the extrusion process, many researchers have worked on the extrusion process using different methods to achieve their aims. This experiment was conducted with three different lubricants namely: Castor oil, Palm Oil and tropical coconut oil; as well as without lubricants. Different lubricating conditions were employed of varying strain rates ranges from 1.5×10-3s-1, 2.0×10-3s-1, 2.5×10-3s-1, and 3.0×10-3s-1; Numerical analysis and simulation for dry and lubricated conditions during extrusion load were also performed using DEFORM 3D software. The results show that prediction extrusion load increases with increasing strain rates. The maximum extrusion load was found to be higher for extrusion without lubricants. In all cases of strain rate, palm oil showed a lower extrusion load compared to the other lubricants. Castor oil indicated the highest extrusion load when the experiment was carried out using lubrication. There was a consistent agreement between the result gotten from the experiment and simulation results of the extrusion load-strike curve.Peer reviewedFinal Published versio

Compressive Strength and Thermogravimetric Analysis of Metakaolin Blended Cement

Cement concrete is the most extensively used construction materials across the world. The environmental unfriendliness attached to the production of cement which is one of the major constituents of concrete demands persistent attention and the wide use of pozzolanic material as partial replacement of cement in concrete looks to be a promising supplement for cement in concrete production.  Based on past research works, metakaolin was selected and its compressive strength and thermal resistance as well as other properties were determined. The replacement percentage of metakaolin employed was 5%, 10%, 15% and 20% by weight of cement with a mix ratio of cement to sand to granite of 1:2:4 cured at 7 days, 14 days, 28 days and 56 days . The output of this research work shows that with respect to compressive strength and thermal resistance, the metakaolin blended cement examined here is not suitable as supplementary materials for cement in construction industry

EXPERIMENTAL AND THEORETICAL INVESTIGATION OF TENSILE STRESS DISTRIBUTION DURING ALUMINIUM WIRE DRAWING

Wire drawing, has received a wide range of applications in the production. A wide number of cable applications demand that the cable survive high tensile loading. This works entails experimental and theoretical investigation of tensile stress distribution during aluminium wire drawing. The initial Aluminium rod used in this work was, 9.50mm with density of 2700kg/m3 , young’s modulus of (7x1010 Pa), Poisson’s ratio (0.33), Yield stress in simple tension (21.7 × 106Pa), which was later drawn to different diameter as required and tensile testing was carried out on each required diameter. In this work, tensile stress distribution in the drawing process is determined via experimental and analytical method. A free body equilibrium method is used to obtain the equations that dictate the drawing phenomenon. The result obtained by experiment is compared with improved model and also with other solutions found in the literature about these themes, particularly, with Rogas solutions in slab method case. There is high degree of similarity between the result obtained experimentally and the simulation of improved model but there is a wide gap when compared experimental result with simulation of classical slab method. Thus, the result of the study will be of great benefit to industries that make use of aluminium wire as electrical wiring, cables, spokes for wheels, stringed musical instruments, paper clips and tension-loaded structural components and also automotive sector. This will help them determining the extent of tensile loading that the aluminium wires their working on can withstand before failure can occur

Review on thermal, thermo-mechanical and thermal stress distribution during friction stir welding

Abstract: Thermal has significant effects on the metal structure during welding process; it plays vital roles in rearranging molecular structure of the metal being welded. It is of great importance to have the knowledge of thermal, temperature, thermo-mechanical and heat distribution on the workpiece in friction stir welding as this will help in designing process and the model parameters for welding application in the following welded joints, edge butt, lap, square butt, T lap, fillet, multiple lap etc. The physics of heat generation must be explored in order to understand the workability of friction stir welding (FSW). The FSW process begun with initial friction of mechanical that took place between the tool and the welded surface resulting in the generation of heat. Since the discovery of Friction Stir Welding (FSW) in 1991, many researchers have done tremendous investigations into the process and many experimental, theoretical, numerical, empirical, computational and analytical methods have been carried out in order to analyse and optimize FSW and to understand the complex mechanism in friction stir welding at the same time to deal with effects of various parameters relating to thermal profile during the process of FSW

Piezoelectric effects on bone modeling for enhanced sustainability

© 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)Bone tissue possesses piezoelectric properties, allowing mechanical forces to be converted into electrical potentials. Piezoelectricity has been demonstrated to play a crucial role in bone remodelling and adaptability. Bone remodelling models that consider strain adaptation, both with and without piezoelectric effects, were simulated and validated in this study. This simulation help to better comprehend the interplay between mechanical and electrical stimulations during these processes. This study aimed to optimise the modelling of piezoelectric effects in bone modelling analysis. The connection between mechanical loads applied to bones and the resulting electrical charges generated by the piezoelectric effect was examined. Furthermore, mathematical modelling and simulation techniques were employed to enhance the piezoelectric effect and promote bone tissue growth and repair. The findings from this research have substantial implications for developing novel therapies for bone-related diseases and injuries. It was observed that electrically stimulated bone surfaces increased bone deposition. In some instances of physical disability or osteoporosis, therapeutic electrical stimulation can supplement the mechanical stresses of regular exercise to prevent bone loss. Consequently, the bone remodelling method on the software platform enables easy application and repetition of finite element analysis. This study significantly benefits bone tissue/biomedical engineering, particularly in bone remodelling, healing, and repair.Peer reviewe

Improvement of ASTM A53 Steel Durability Using Agrowastes as Carburizing Agent

 The importance of steel in manufacturing and construction over the past century cannot be over-emphasized and easy accessibility couple with excellent mechanical properties make it preferable over others. However, the problem of durability has posed a serious concern as majority of steel application are meant for long term use. Several attempts have been made to improve the durability of steel in the past and increase of carbon content in low carbon steel was found to be a suitable agent. Although getting carbon is not the challenge rather obtaining it from a sustainable source that has zero environment impact. This research identified two separate agro-waste that has high carbon content the issue of sustainability brought about the development of carburizing agent from agro-waste that are easily accessible namely palm kernel and eggshell which is employed in this research. The use of agro-waste was found to be effective as there was notable increase in grain structure of the carburized steel when compared to the control sample without carburized agent in it