Key Engineering Materials Vols. 594-595

Abstract: Materials research is often characterized as a pure scientific activity. However, such approach cannot be applied when materials researchers must deal with Appropriate Technology (AT) development. Science and engineering which focus on pure scientific background must be integrated with appropriateness of AT in engineering and technology levels. This study aims to discover such integration by investigating right positioning of materials research to AT development at the intersections between materials research and AT in Science, Engineering, and Technology research areas. Seven pillars of survivability which describe the tiers of appropriateness are also taken as the basis of exploration. They are coupled with the intersections to deliver complete overview of research positioning of materials research in AT development. This study concludes that materials researchers become the inventors (Science), innovators (Engineering), and constructors (Technology) of materials used in AT. They have to produce materials for AT that that must be able (Science), feasible (Engineering), and visible (Technology) to improve local activities through a technological solution. By looking at the discussion, this study contributes in several issues at once: AT, materials research, and research design, including all aspects considered as the fundamental principles of survivability, by taking these issues in the positioning of materials research in AT development.

Abstract: The purpose of this research is to design and to modify a monomer reactor tank in order to achieve higher output production of bio-monomer. The main aspect of this design is based on producing good quality and higher yielding of monomer. The design was started on lab scale process of 2L beaker into a 5L reactor. The most important point of the design is to produce larger amount of monomer as compared to lab scale equipment. Selecting material is vital on the process and cost for fabricating the reactor. It is to prevent chemical corrosion on the reactor and to produce higher yield of monomer with cost effective way. The optimization and analysis of the design and materials of a reactor were based on influence of heat and chemical resistance on the reactor. The design and analysis process were done using Solidworks and chemical resistance were based on the standard chemical chart for common materials used for a reactor. The best material for the reactor is Stainless Steel 316 based on chemical chart, heat resistance and cost effective. The yielding of monomer is more than 100% by lab scale method with predetermined controlled parameters of stirring speed and temperature. There were small differences between every samples. At 80°C, the yielding of monomer is the highest while the by product (water) is the lowest. Meanwhile, at 60°C the monomer yielding is the lowest with highest by-product.

Abstract: A laboratory-scale study was conducted using a combination of SSF and FWS constructed wetland planted with Limnocharis flava and Eichhornia crassipes to treat landfill leachate. The effects of hydraulic loading rate (HLR) on pollutant removal in landfill leachate as well as the difference in performance between the planted and control system were investigated. The HLR in the system was varied at 0.39 m/d and 0.55 m/d. The results showed that the SSF-FWS constructed wetland was successful in reducing the pH value, TSS and turbidity. The removal efficiency of TSS and turbidity were achieved 98.32% and 97.43%, respectively at 0.39 m/d HLR. The study concluded that different HLR and the presence of wetland plants have given significant effects on the constructed wetland performance.

Abstract: A low cost adsorbent for waste water treatment can be achieved by producing an activated carbon from agriculture waste. In this research work, the activated carbons were prepared from durian shell using the physical and chemical activation at different concentrations of hydrogen peroxide followed by carbonization at high temperature under the flow of nitrogen gas. The produced activated carbon was characterized to obtain the physical and chemical properties. The adsorption of methylene blue dye has been studied in this experiment and the results showed that the efficiency of dye removal was increased for the treated durian shell as compare to the untreated one. It is found that 99% of methylene blue has been removed using durian shell activated carbon (DShAC) that treated at the conditions 0.6M H₂O₂ at 700°C for 30 minutes.

Abstract: The price fluctuation and negative environmental effect of mineral oil-based lubricant are the main factors which instigate the research on high-oleic vegetable oil as its possible replacement. In this study, the factors involved in blending process of waste cooking oil (WCO) and Jatropha curcas oil (JCO) as biolubricant basestock were investigated using 2-level factorial design. The molar ratio of WCO to the JCO (WCO:JCO), stirring speed and blending times were the three factors studied. The WCO:JCO, stirring speed and the blending time were found to be significant to the increased of oleic acid content in the basestock. The highest percentage of oleic acid achieved was 53.31 % at molar ratio of WCO:JCO at 20:80, 350 rpm and time at 30 minutes. Thus this study exposed the potential of new blending oil which are comparable with other vegetable and mineral oils as base stock for bio-lubricant in term of fatty acid compositions.

Abstract: Enzymatic synthesis of kojic ester, a bio-based whitening agent, was successfully carried out via esterification reaction between oleic acid and kojic acid. Commercial immobilized lipases of Novozym 435 and Lipozyme RM IM were used in combination as biocatalyst in the reaction system. Various reaction parameters were chosen to optimize the reaction in order to obtain a high yield of kojic ester including the best ratio of lipases, reaction time and reaction temperature. The optimum conditions for the synthesis of kojic ester was achieved at reaction time of 12 hours, temperature of 60 ^οC and equal ratio of lipases to produce more than 70 % yield. Antimicrobial tests of synthesized kojic ester towards several types of bacteria via Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) analyses were also examined. The results obtained suggested that kojic ester exhibits a good bactericidal effect towards all bacteria tested such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium.

Abstract: Proteins levels produced by bacteria may be increased in stressful surroundings, such as in the presence of antibiotics. It appears that many antimicrobial agents or antibiotics, when used at low concentrations, have in common the ability to activate or repress gene transcription, which is distinct from their inhibitory effect. There have been comparatively few studies on the potential of antibiotics or natural compounds in nature as a specific chemical signal that can trigger a variety of biological functions. Therefore, this study was focusing on the effect of essential oil from Cymbopogon flexuosus in regulating proteins production by Bacillus subtilis ATCC21332. The Minimum Inhibition Concentration (MIC) of the C. flexuosus essential oil on B. subtilis was determined by using microdilution assay, resulting 1.76mg/ml. The bacteria cells were further exposed to the C. flexuosus essential oil at concentration of 0.01 MIC for 72 h. The proteins were then isolated and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Proteins profile showed that a band with approximate size of 30 kDa was appeared for the treated bacteria with C. flexuosus essential oil. Thus, B. subtilis ATCC21332 in stressful condition with the presence of C. flexuosus essential oils at low concentration could induce the protein production. The isolated protein also showed antimicrobial activity against selected Gram-positive and Gram-negative bacteria.

Abstract: Hybrid compounds of multiwalled carbon nanotubes-alumina (MWCNT-Al₂O₃) were grown by chemical vapour deposition (CVD) method of methane. The catalyst effect and growth of the synthesis of the multiwalled carbon nanotubes-alumina (MWCNT-Al₂O₃) hybrid compound in three different supported catalysts (Ni, Co and Fe nitrates) were being compared. X-Ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) were employed for the characterization of the hybrid compound. The results revealed that the Ni nitrates catalysts showed a better growth rate performance than Co Nitrates and Fe Nitrates. With respect to the diameter of the MWCNT-Al₂O_3, the Fe nitrate showed lengthens in diameter compared to Co Nitrates and Ni Nitrates catalyst. This indicated that the growths of these carbon structures can be controlled and manipulated by the supported catalyst.

Abstract: The effect of cement replacement materials on hydration of solidified waste in ordinary Portland cement has been investigated based on initial setting time. Five cement replacement materials namely, rice husk ash, condensed silica fume, activated carbon, fly ash and meta kaolin were selected for solidified organic waste in the cement. The initial setting time was conducted with incorporation of 5 to 15 percent cement replacement materials at water to cement ratio of 0.45. The initial set of cement involves mainly the development of ettringite fibers and portlandite. Additions of CSF, FA and AC have delayed the initial setting time. The governing factors contributed to the delayed in setting time are the cement replacement materials, particle size and composition, which significantly retard development of ettringite fibers. 5 % MK and RHA tend to accelerate the setting with 138 and 150 minutes, accordingly as these binders have larger particle size.

Abstract: This paper presented the load versus displacement curve for experimental work and validated with modeling results. A full-scale specimen which representing retrofitted precast RC beam-column exterior joint with corbels was tested in the laboratory under reversible lateral cyclic loading until ±1.75% interstorey drift. The specimen was rehabilitated by using Carbon Fiber Reinforced Polymer (CFRP) wrapping method. Modeling work was carried out using Ruaumoko Hysteres Program. A curve representing load versus displacement for beam-column exterior joint is generated using Pampanin Reinforced Concrete Beam-Column Joint Hysteresis rule with reloading slip factor. The modeling result was compared with the load versus displacement curve obtained from experimental work. It was found that the hysteresis loops exhibited good agreement between experimental and modeling results. The effective stiffness, displacement ductility and equivalent viscous damping for the specimen were also discussed and compared.