Journal of Engineering and Technological Sciences
Not a member yet
888 research outputs found
Sort by
Microwave-assisted Synthesis of Functionalized Multiwalled Carbon Nanotube–Titanium Dioxide Hybrid Structure and Photodegradation
Get PDFDecoration of a functionalized multiwalled carbon nanotube (f-MWCNT) surface with titanium dioxide (TiO2) was designed to improve its photocatalytic degradation performance. Structural decoration was achieved by microwave heating at various mass ratios (1:2; 1:4; 1:8; 1:16 wt.%) of titanium (IV) isopropoxide as precursor. The hybrid structure of TiO2/f-MWCNT was characterized by scanning electron microscope and transmission electron microscope (TEM). The crystallite form of the TiO2 nanoparticles was further studied by X-ray diffraction (XRD) and HR–TEM. We report the conformation of high-density TiO2 coated on an f-MWCNT surface at a mass ratio of 1:16 wt.%. XRD analysis revealed a structural transformation from mixture phase (anatase–brookite) at mass ratios of 1:2 and 1:4 wt.% to fully anatase phase for mass ratios of 1:8 and 1:16 wt.%. The transformation was also confirmed by selected area electron diffraction (SAED) and HR–TEM analysis. Our results showed that anatase phase plays a significant role in photodegradation activity
Production of Carotenoids from Oil Palm Empty Fruit Bunches: Selection of Extraction Methods
Get PDFPublic awareness of the importance of natural food colorants is increasing. Carotenoids is one of the coloring agents which widely used for food applications to give yellow, orange, or red color in food products. Natural carotenoids can be produced by extraction from various sources, such as carrots and palm oil, or from algae and fungi. Oil Palm Empty Fruit Bunches (OPEFB) as the biomass waste of palm oil industry may still contain carotenoid residue and thereby extraction of OPEFB constitutes the crucial step in carotenoid production. The effects of solvent used for the extraction as well as the size of different parts of OPEFB on the obtained carotenoid were evaluated. The experiments were performed by soxhlet extractor using n-hexane, ethanol, and isopropyl alcohol solvents at the boiling points of each solvent. The ratio of OPEFB to the solvent is 1:60 (w/v) with the variations of the OPEFB size. The results showed that the optimum carotene concentration was obtained from extraction using n-hexane to 1 cm OPEFB spikelet
Distribution of Microplastics along Mai Khao Coastline, Phuket
Get PDFThe distribution of microplastics at Mai Khao beach, Phuket, Thailand was studied. A total of 12 samples from four sample sites with 0.5 m x 0.5 m quadrats were taken at the intertidal zone during March and July, 2020, and sorted into two size classes (>300 µm and 20 to 300 µm). The mean abundance of microplastics at Mai Khao beach ranged from 44.08 to 68.7 items kg-1 d.w. for >300 µm and from 90.6 to 106.1 items kg-1 d.w. for the 20 to 300 µm range. White (44.94%) and blue (23.60%) colors, and fiber shape (94.5%) were dominant in particle counts; and based on µFTIR analysis the dominant polymer type was polyethylene terephthalate (94.7% by number count), with considerable fractions of cotton and cellophane. The microplastic characteristics suggest anthropogenic activities as possible sources. Notably, the abundance of microplastic found in the study area was definitely higher than at other sites investigated along the west coast or Phuket. Significant differences in the abundances of the two microplastic size classes were observed (p < 0.05), indicating that the microplastics in Mai Khao beach can accumulate in the marine food chain and transfer up along the trophic levels. Therefore, urgent attention should be given to the contamination problem, with a proper management system and a public awareness campaign, to reduce the effects of microplastic on organisms and ecosystems
Effect of Alkaline Treatment on Physical and Tensile Properties of Areca Leaf Sheaths (ALSs) used for Biodegradable ALS Plate Production
Get PDFThis research evaluated the possibility of alkaline treatment to solve the problem of molding due to moisture during storage of areca leaf sheaths (ALSs) to be used for biodegradable ALS plate production. The effect of alkaline treatment on the properties of ALSs was studied. Sodium hydroxide (NaOH) and sodium bicarbonate (NaHCO3) were used as chemicals for surface treatment. The solution of NaOH and NaHCO3 was varied at 1%, 3%, and 5% w/v. Surface treatment with NaOH and NaHCO3 partially removed hemicellulose, cellulose, lignin, and impurities from the surface of the ALSs and increased the moisture resistance property of the ALSs. Treatment with NaOH made the ALSs’ surface rougher, whereas treatment with NaHCO3 had no effect on the surface of the ALSs. The decomposition temperature (Td2) of the NaOH-treated ALSs decreased by approximately 7.0 to 10.5%, while for the NaHCO3-treated ALSs it changed only slightly. The overall tensile properties of the NaOH-treated ALSs were better than those of the NaHCO3-treated ALSs. The surface treatment with 1% NaOH and 1% NaHCO3 increased the tensile modulus by 20.5% and 6.2%, respectively, as compared with the nontreated ALS. It was found that surface treatment with 1% NaOH and 1% NaHCO3 could create suitable conditions for ALS plate production. This work is a preliminary study; more research still needs to be done
Study of COVID-19 Health Protocol Standards in Construction Industry of Indonesia
Get PDFDue to the increase in GNI per capita, the Indonesian government has launched its national economic recovery program in response to the COVID-19 emergency crisis, known as the New Normal and ordered to partially resume on-hold infrastructure projects followed by the implementation of a new, integrated COVID-19 health protocol. This research presents a study of health protocol standard implementation in the construction industry with the aim of formulating recommendations for minimum criteria elements that can be used for construction services companies at all levels. The domain-taxonomy analysis approach was used as the research method: the ISO/PAS 45005:2020 and ILO standards were adapted to Ministerial Regulation of PUPR No. 10 Year 2020. A gap analysis was conducted with Singapore, Malaysia, and Australia. The analysis generated four segregated main groups of elements with level-2 sub criteria. The main groups of elements were: Planning, Prevention, Handling, and Control and Evaluation. These criteria were validated and implemented in a case study of state-owned construction enterprises, here called PT. X and PT. Y, with large, qualified construction companies. From the implementation analysis it was found that PT. X and PT. Y had implemented the minimum criteria of the COVID-19 health protocol for construction workers very well
Perspective and Prospects of Wire Electric Discharge Machining (WEDM)
Get PDFWire Electric Discharge Machining (WEDM) is a non-traditional machining method that is widely used in the manufacture of aerospace/aircraft and medical equipment for conductive materials. WEDM products are expected to have good dimensional accuracy, surface roughness, and geometry. Many researchers have done experiments on various materials to optimize the process, which has many parameters and response characteristics. This paper provides an overview of the WEDM process on alloy steels in order to understand the impact of input process variables on output responses and optimization techniques for selecting optimal process parameters. This paper also highlights WEDM process trends as well as workpiece materials, wire varieties, wire diameters, and optimization approaches. This work is expected to be useful in initiating further research on WEDM by documenting substantial research works confirming the latest scenario
Discretization Corrected Particle Strength Exchange for Steady State Linear Elasticity
Get PDFDiscretization corrected particle strength exchange (DC PSE) is a particle based spatial differential operator designed to solve meshless continuum mechanics problems. DC PSE is a spatial gradient operator that can discretize a computational domain with randomly distributed particles, provided that each particle has enough neighboring particles. In contrast, conventional methods such as the standard finite difference method require the computational domain to be discretized into a Cartesian grid. In linear elasticity simulations, especially steady state cases, this domain is mostly discretized using mesh-based methods such as finite element. However, while particle methods such as smoothed particle hydrodynamics (SPH) have been widely applied to solve dynamic elasticity problems, they have rarely been used in steady state simulations. In this study, a DC PSE operator was used to solve steady linear elasticity problems in a two-dimensional domain. The result of the DC PSE numerical simulation was compared to numerical results, empirical formula results, and results from conventional commercial finite element software, respectively