Advances in Science and Technology Vol. 141

Abstract: The aim of this work is to synthesis nanoparticles from bamboo charcoal and identify the majority elements of the nanoparticles. The bamboo charcoal is made by pyrolysis process. The charcoal was manually pulverized before being sieved through a filter with a mesh size of 200. The synthesis of the nanoparticle was conducted by using a top-down approach of ball milling process. The charcoal powder that had passed through the filter and the milling balls of steel were then poured into a vial of glass. In the vial, the milling operation was carried out. The vial had a diameter of 71 mm and a length of 119 mm, while the ball's diameter was 0.25 inches. To have the balls collide and reduce the size of the charcoal particles, the vial was rotated. 5 million cycles at 500 revolutions per minutes were performed on the shaker machine. The empty space in the vial was one third of vial volume for the movement of the milling balls. The ball milling process was separated into two conditions, namely dry and wet. For the wet procedure, the particles are filtered to separate the particles based on their size. The particle morphology, size, and elements in the particle produced by the process were examined using a scanning electron microscope (SEM) and an Energy Dispersive X-ray (EDX). The results showed that the size of the particles of the dry procedure is un-uniform in the range of about 300 nm to 600 nm with irregular shape. The dominant element is carbon. The wet procedure produced a more uniform size in the range of 100 nm to 200 nm with also irregular shape. The most dominant element is also carbon.

Abstract: Protein-stabilized gold nanoclusters have been intensively studied due to their excellent fluorescent properties and potential biomedical applications. Human Serum Albumin is abundant in human blood. Here, we synthesized human serum albumin-stabilized gold nanoclusters. The gold nanoclusters were characterized and used for glucose sensing. It is found that the human serum albumin encapsulated gold nanoclusters emit bright red fluorescent with a long fluorescence lifetime in the range of microseconds. The fluorescence intensity for gold nanoclusters decreased as the concentration of added glucose increased. The fluorescence intensity decreases due to the by-product (H₂O₂) from the enzymatic reaction of glucose oxidase. The Au-S bond can be destroyed by Hydrogen Peroxidase (H₂O₂). The fluorescence lifetime value of gold nanoclusters is unchanged in the presence and absence of glucose. This unchanged fluorescence lifetime obeyed a simple static quenching mechanism and indicated the destruction in the structure of gold nanoclusters, leading to the quenching of fluorescence intensity. This work suggests that human serum albumin-encapsulated gold nanoclusters can be used for glucose detection with a detection limit of 0.5×10^-6 mol/L.

Abstract: A nickel laterite ore sample from the Obi Island of North Maluku, Indonesia was thermally treated using corncob charcoal as a reductant to determine the effect of corncob charcoal addition on the chemical change and phase transformation. Mineralogical analysis of raw ore sample and calcines was performed using optical microscopy and X-ray diffraction methods, whereas chemical composition was determined employing X-ray fluorescence (XRF) spectrometry. The ore was then calcined at 1.000°C for 1 hour with the mass variable of corncob charcoal as reductant was 5,10,15, and 20%. After calcination, the products were then weighed and analyzed using microscopic, XRD, and XRF methods. The results of material characterization showed that the ore sample is dominated by goethite. Antigorite, quartz, and hematite are also present in small quantities. The ore sample contains 1.53% Ni, 18.84% Fe, and an SM ratio of 2.46%. The experimental results showed that the optimum condition was achieved with the addition of 10% corncob reductant where the calcined product contains 1.88% Ni, 14.22% Fe, and SM ratio of 1.72. The increase of corncob charcoal addition >10% resulted in slight decrease of Ni reduction likely due to increase of Fe metallization.

Abstract: The article provides information about the initial elements in the waste and tailings of the copper processing plant of the Almalyk Mining and Metallurgical Combine and theoretical solutions for the extraction of metals. According to chemical data, the amount of iron in the waste is high (52.6%), and the most effective solution for extracting iron from the waste is the reduction process. An increase in the amount of iron to 88.9% was formed using coal and lime as reducing agents.

Abstract: The development of drag and lift balance aimed to modify and creating a measuring instrument that may be used in the field of aerodynamics or in testing aerodynamic properties. This measurement is in the form of wind speed on an object model such as airfoils, building models and automotive technology. This design uses an open circuit wind tunnel with a low turbulence subsonic type, with a maximum air speed of 30 m/s. The exsisting wind tunnel still uses an analogue measuring instrument which is then modify in a digital arduino-based for drag and lift balance measuring instrument with a drag and lift sensor maximum load of 1kg (v=30m/s) and maximum air speed of 50m/s. The Measuring instrument is calibrated using a 1kg weight test equipment for testing with the test object model (spherical, hemispherical, cylindrical, cube) and three types of airfoil models. The test results are in the form of drag coefficient (C_d) and lift coefficient (C_L). The coefficient of drag is greatest in the cube shape and lowest in the sphere, but will decrease in value at a speed of 20 m/s. In the airfoil, the values ​​of C_d and C_L have the same trend with the literature with an uncertainty value of less than 10%. The value of C_L / C_d will increase as the angle of attack increases, but can very significantly depending on the fluid, airfoil, and aircraft type.

Abstract: The sun is a heat and photonic energy source that can be used as a renewable and sustainable energy source. Solar panels have used thermoelectric generators in a hybrid solar cell system to increase the efficiency of solar energy utilization. The main objective of this study was to investigate the role of thermoelectric material on the increased power of the hybrid power system. The solar cell system was built using a fixed-axis panel. The tilt angle was selected to improve the received solar radiation on the photovoltaic panel. The measurement tools were attached to the panel, including the temperature and electrical output tools. The tool was calibrated using the tool standard to obtain a reliable result. Uncertainty analysis was conducted to predict the accuracy of the measured data. All measurements were recorded in real-time and stored in a data logger. The experiments were carried out from 05:00-18:00 Western Indonesia Time. The efficiency of photovoltaic and thermoelectric generators was calculated to know each contribution to the hybrid power system.

Abstract: The coal switch program carried out by Power Plant of Paiton Unit 8 has caused excessive slagging in the boiler area that is not installed sootblower, the formation of slagging and fouling causes problems and chain effects in boiler operations which result in a decrease in boiler efficiency. A 2019 boiler inspection revealed significant slagging located on the rear screen tube, vertical backpass tube, lower rear reheat tube banks, and the upper location between the final reheat and final superheater division panels. This study aims to directly observe the performance of the boiler, then a calculation analysis is carried out using the direct method, namely by making a direct comparison between the heat absorbed by the working fluid in the boiler with the heat produced by fuel before and after the addition of a sootblower in the superheater division panel boiler area of Power Plant of Paiton Unit 8. The observation results found that the addition of a sootblower increased boiler efficiency by 3,115%, reduced CO₂ gas emissions by 21,983,423 tons e CO₂ and saved coal consumption costs of USD 1,550,640.

Abstract: The wear failure is widely found in steel bars used for coal screener machines in the mining industries. The failed parts of such components require immediate replacement to lengthen the machine's service life. This work aimed to investigate the structure and properties of the worn bar of a screener machine after experiencing wear failure and analyze the wear mechanism. The work started by machining the sample from the original bar, then grinding and polishing. The microstructure of the worn samples was observed using SEM and XRD. The hardness distribution of the bar was measured from the periphery to the core. The results of this work would provide evidence of wear sources responsible for the wear failure.