Spektra: Jurnal Fisika dan Aplikasinya
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THE EFFECT OF VARIATION CONCENTRATION AND DEPOSITION PARAMETER TO THE OPTICAL CHARACTERISTICS AND THE CRYSTALLITE PROPERTIES OF ZINC OXIDE
Full text linkThe objective of the study was to obtain the ZnO thin films with variation concentration of zinc acetate dehydrate (ZAD), and variation of spin coater speed and rotation time. We observed the effect of the former parameters on the optical characteristics that comprised of the spectrum of absorption, transmittance, and ZnO crystallite size from UV-Vis spectrometer and XRD orderly. For the analysis of the effect of the variation of concentration, ZAD diluted into ethanol with the concentration 0.1M, 0.25M, 0.5M, 0.75M and 1M, with the addition of diethanolamine (DEA). Then it was deposited on the glass substrate with spin coater, continued by the heating on the hotplate with the number of layer's variation. For the analysis of deposition parameter effect on the transmittance and the size of ZnO crystal, we used 0.25M ZnO precursor solution with the addition of DEA, then deposited by speed and time of rotation of spin coater of 1230 rpm, 2500 rpm, and 3200 rpm for 10, 15 and 30 seconds of each. The smallest absorbance value 0.05 obtained for single layer 0.1M ZnO, while the maximum transmittance value obtained for three-layer 0.25M ZnO. Concentration variation did not affect the energy gap, whose value was approximately 3.2 eV for all samples. From the XRD result, we found that deposition time affected the number of diffraction lines, the size of the crystallite, and the transmittance
BIOFILTER MANUFACTURE OF AZADIRACHTA INDICA LEAF POWDER AND ITS EFFECTIVENESS IN CAPTURING FREE RADICALS OF CIGARETTE SMOKE
Full text linkFree radicals from cigarette smoke are a dangerous part that must be found to counteract. This research aims to make a composite biofilter made from Azadirachta Indica to ward off/capture free radicals from cigarette smoke. This biofilter is made with Azadirachta Indica leaf powder added to polyethylene glycol as the matrix. The biofilter was then seen for its physical characteristics; the density and porosity were tested using SEM. Furthermore, a biofilter membrane is used to filter cigarette smoke. Cigarette smoke that passes through the biofilter is then analyzed using ESR for its free radical content. The results showed that the biofilter made from Azadirachta Indica leaves could absorb several types of suspected free radicals in cigarette smoke. Biofilters using PEG as a matrix with a mass of 0.9 and 1gr were the most effective in absorbing the suspected types of free radicals. SEM test showed an average pore size of 2-3 µm for a mass of 1gr with PEG as the matrix
STUDY OF CRUSTAL STRUCTURE OF THE FLORES ISLAND USING RECEIVER FUNCTION METHOD
Full text linkFlores is an island located in the north of the East Nusa Tenggara region. Formed as a consequence of very complex tectonic setting that might cause relatively high level of seismic in the region. This study aims to characterize the crust structure based on the S wave velocity model, the Vp/Vs ratio, and crustal thickness beneath the station on Flores Island. This study was using receiver function analysis method of teleseismic earthquake data with magnitude criteria ≥ 6 and epicenter distance 30⁰-90⁰. Seismic signal recorded on broadband stations three components. This study was using LBFI station. Velocity model of S wave and Vp/Vs ratio determined by using the non-linear Neighbourhood Algorithm (NA) inversion. Furthermore, the velocity and Vp/Vs ratio models will be used to obtain the depth of the migration process of the amplitude of the receiver function to depth. From the results of processing the depth of the Moho layer on the island of Flores under the LBFI station was identified as 41 km. The existence of the slab can be identified quite well that is at depth about 110 to 140 km
CHARACTERIZATION OF (Mg0.6Zn0.4)TiO3 CERAMICS AS DIELECTRIC RESONATOR MATERIALS IN MICROWAVE FREQUENCIES
Full text linkCeramics based on magnesium titanate (MgTiO3) are dielectric materials that have the potential to be used in telecommunications systems at microwave frequencies, such as filters, antennas, and signal generators. This study aims to characterize the resonant frequency and output power of (Mg0.6Zn0.4)TiO3 ceramics (abbreviated MZT04) as a dielectric resonator (DR) material in a DRO circuit and relate it to the structure, microstructure, and bulk density data of the ceramics. The MZT04 ceramics were fabricated by compacting MZT04 powder at a pressure of 2.5 MPa using a cylindrical die press of 5 mm in diameter to become pellets with the same diameter. The pellets were sintered at 1300 ℃ by varying holding time for 6, 8, and 10 h to become ceramics. Data on the structure of the ceramics were obtained from the X-Ray Diffraction (XRD) pattern with Cu-Kα radiation which showed that the three ceramics contained MgTiO3 phase, each 87.02; 90.55; and 87.40 % molar, the rest % is MgO and TiO2 rutile phases. The increase in sinter holding time has increased the unit cell volume of the MgTiO3 phase from (307.94), (308.61), to (308.94) Å3; the size of the lattice parameters (a=b, c) also increased from (5.057, 13.903) Å, (5.058, 13.903) Å, to (5.061, 13.914) Å; like wise, the bulk density increased from 2.51, 2.82, and 3.04 g/cm3. As a DR material, the three ceramics exhibit a resonant frequency signal each at 5.20; 5.21; and 5.22 GHz with the output power of -19.70; -14.47; -15.70 dBm, and the FWHM of the signal is 59.3; 61.6; and 61.2 MHz. Therefore, MZT04 ceramics can be applied as the DR material in microwave frequencies, especially at ~5.20 GHz. The variations in sinter holding time is not significant effect on the position of the resonant frequency
IMPACT PROFILE OF ENSO AND DIPOLE MODE ON RAINFALL AS ANTICIPATION OF HYDROMETEOROLOGICAL DISASTERS IN THE PROVINCE OF SOUTH SUMATRA
Full text linkEl Niño Southern Oscillation (ENSO) is a weather phenomenon in the Pacific Ocean. At the same time, Dipole Mode (DM) is an ocean-atmosphere interaction phenomenon in the Indian Ocean. The area of South Sumatra Province, which is in the Monsunal area, makes the influence of ENSO and DM very instrumental in determining the length of the rainy season and throughout the year. The South Sumatra region is very vulnerable to forest and land fire disasters due to the condition of the area in the form of swamps and peatlands, which are very easy to burn if the dry season occurs in the South Sumatra area. In this study, an analysis of the effect of ENSO and DM on rainfall in the South Sumatra Region from 1981 to 2020 was carried out using a simple linear regression method and the correlation coefficient using Niño 3.4 index data and Dipole Mode with rainfall data and consecutive rainy days data. Consecutive Wet Day (CWD). The purpose of this study was to determine the effect of Enso and Dipole Mode on rainfall and CWD in the South Sumatra Region. The results show that the correlation between ENSO and rainfall is 0.0017-0.002573, DM and rainfall is 0.05972, and ENSO and CWD is -0.068. The correlation between DMI and CWD is 0.513. So it can be said that ENSO and DMI have no effect on rainfall in the South Sumatra Province. Still, the amount of CWD in South Sumatra Province is significantly determined by the Dipole Mode Index (DMI) at a moderate level. The number of consecutive rainy days in South Sumatra Province is influenced by the dynamics of the ocean and atmosphere of the Indian Ocean, which is characterized by the presence of positive IOD and negative IOD phenomena
FABRICATION OF PLASTIC SCINTILLATOR USING POLYSTYRENE MATRIX BASED
Full text linkExperiments on making a plastic scintillator with polystyrene as a base material mixed with fluorescent compounds (primary and secondary dopants) have been performed. Primary dopants (PTP) used to produce emission at wavelengths of visible light and secondary dopants (POPOP) to shift the visible wavelengths to wavelengths that could be detected by Photomultiplier Tube (PMT) ) were carried out. Experiments were performed on the melting points condition of these materials, which had previously been subjected to a thermo-mechanical analysis using a Thermogravimetric Analysis-Differential Scanning Calorimetry (TGA-DSC) machine, where the melting point was in the range of 200-240°C. Furthermore, the fabrication was carried out using the extrusion technique, where polystyrene pellets mixed with PTP (1.5% by weight) and POPOP (0.05% by weight) were fed into an extrusion machine which has four hot areas to obtain a thin plate plastic scintillator. The plates were then analyzed with a UV-Vis Spectrophotometer to determine the absorption spectrum and Fluorescence Spectrophotometer to determine the emission spectrum. From the results of the analysis, it was found that the samples that went through scintillation pellets and without the addition of antioxidants had absorption spectrum data of 330 nm and emission spectrum of 421 nm. These values are in accordance with the characteristics of plastic scintillators on the market. 
IDENTIFICATION OF SOIL CORROSION POTENTIAL FOR PLANNING IN THE GAS PIPELINE CATHODIC PROTECTION SYSTEM
Full text linkResearch has been carried out to map and identify the potential for soil corrosion for the planning of cathodic gas pipeline protection systems. The research location is located in Cimanggis - Bitung, West Java, which is located at coordinates 6o19'00 "- 6o28'00" South Latitude and 106o43'00 "- 106o 55'30" East Longitude. Measurement of soil resistivity using the Wenner method that refers to ASTM G37, with variations in the distance of 0,75m, 1,50m, 2,50m and 6,00m with the number of measuring points as many as 185 points. Based on the results of data processing and soil resistivity interpretation seen that there are several locations that have low to extreme corrosion levels. Therefore, for these locations, technical planning and calculation for the protection of the pipeline to be installed is necessary