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PublicationEffect of different substrates and white Oyster mushroom loading on production of fungal foam(AIP Publishing, 2023)In this study, agricultural wastes including rice husks, banana leaves and teak leaves were used to produce fungal foam through the cultivation with Pleurotus ostreatus fungi. The fungi are inoculated using different substrates and inoculum loadings. The mechanical properties of the foam produced were analysed. The best substrate and inoculum loading were proposed. Among the three substrates used, banana leave produced the best fungal foam in term of mechanical properties at 10 % w/w inoculum loading. The fungal foam can withstand forces high up to 30458.52 gF and have the resilience and springiness of 0.381 and 0.771, respectively. In summary, banana leave fungal foam is suitable as an alternative to the commercial Styrofoam.
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PublicationFailure analysis on U-bend header tube of boiler economizer(IOP Publishing Ltd., 2020)A water tube boiler is a type of boiler in which water circulates in tubes heated externally by fire. It was found that the water tube economizers are often subject to the serious damage mainly because of the overheating and corrosion. Thus, the metallurgical investigation procedures starts with the visual inspection, stereomicroscopy, metallography and chemical analysis methods. It was identified that the failure of the u-bend tube was due to the cracking caused by bending forces during the procedures. This cracking causes a leak for the tube. The appearance of corrosion on the shell side is due to the presence of small content of sulphur under the boiler environment. Several welding imperfections were also detected, however, both corrosion and welding imperfections were not the primary caused of the tube failure. From the analysis, the use of SUS304 grade stainless steel was discovered to be the appropriate material selection for the tube boiler.
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PublicationStructural, electronic and thermoelectric properties of SrTiO₃ ceramic doped by lanthanum using first principles(IOP Publishing Ltd., 2020)The Sr₀.9₂La₀.₀₈TiO₃ model compound was studied by means of the first-principles method grounded on the full-potential linearized augmented plane wave with the local orbital method as implement in WIEN2k. The structures, electronic and thermoelectric properties of the model compound are examined. Geometry optimization of Sr₀.9₂La₀.₀₈TiO₃ compound structure reveals the lattice constant of 3.9451 Å, which is the same as un-doped SrTiO₃. The direct bandgap of 2.48 eV (Γ-Γ) was measured from computed electronic band structure and its displayed density of states for Sr₀.9₂La₀.₀₈TiO₃ sample. Transport properties were calculated using BoltzTraP code as implemented in the WIEN2k code. The results were analyzed as a function of the variable temperatures, the density of state and chemical potential. Temperature and density of state variation with transport properties are in the same trend. Chemical potential proves material as n-type via Seebeck coefficient. The thermoelectric performance ZT of 0.05 was obtained at room temperature, while maximum value of 3.79 was recorded at 1200 K.
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PublicationBotanical insecticide of chili and ginger extract on Nilaparvata lugens, brown planthopper(IOP Publishing Ltd., 2020)Invasion of Nilaparvata lugens or brown planthopper (BPH) in paddy fields has led to the use of excessive chemical insecticides due to its effectiveness. However, excessive applications has contributed several negative effects on the environment, farmers as well as non-targeting organisms. As an alternative, a mixture of a botanical insecticide containing mixture of chili and ginger extracts have been studied. Three parameters were studied namely the extract concentration, time of exposure and temperature of exposure. The results showed that 90% of BPH mortality was found at 40% extract concentration with 72 hr duration time of exposure at optimal temperature 30 C. HPLC analysis proved the presence of capsaicin and gingerol at peaks of 4.502 min and 11.046 min respectively. From repellency analysis, the BPH showed selective repel action against the treated paddy. This is due to the pungent odor contributed from compound of gingerol, shogaol and capsaicin presented in the mixture. Meanwhile, contact toxicity studies have successfully give 100% of mortality of BPH. Microscopic analysis have shown BPH deformities was increased by the extract concentration.
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PublicationBioengineering technologies used for the development and equipment of complex installations to obtain energy from three renewable sources. Complex installations for coastal areas(IOP Publishing Ltd, 2020)Considering that the production of energy from fossil sources causes environmental pollution, increasing health hazards or climate change, the research for new alternative energy sources and the development of high-performance renewable energy conversion systems are a basic concern nowadays. Thus, the development and the use of renewable energy sources can increase diversity in energy supply markets, help to ensure long-term sustainable energy resources, to reduce local and global air emissions, and provide commercial attractive options to meet the specific needs of energy services. This paper aims to improve the efficiency of a patented complex installation which was developed vertically to ensure high-energy efficiency in relation to the occupied area, that integrates three renewable energy sources (wind, solar and hydro), by applying bioengineering solutions. Improvements to the original installation consisted in modifying the initial characteristics of the off-shore system (number of slots, deflectors angle, width of slots and width of deflectors), modification of aerial module blades according to the bioengineering model of the thistle seed (Carduus nutans), and modification of the submerged module paddies according to the bioengineering model of a fish species swimmers. Following the tests performed on the modified complex installation, a major improvement of the energy efficiency compared to the (initial) control installation was observed.