Indonesian Physical Review

ENHANCED THERMAL PERFORMANCE OF POLYETHYLENE GLYCOL-BASED PHASE CHANGE MATERIALS USING ZnO

Tue, 10 Jun 2025 00:00:00 +0100

Polyethylene Glycol (PEG), an organic Phase Change Material (PCM) known for its high latent heat capacity and biocompatibility, suffers from poor thermal conductivity. This research explored the addition of ZnO (at 8 and 12 wt.%) as an enhancer and SDBS as a surfactant, utilizing a two-step homogenization process at 80°C for 4 h. X-ray Diffraction (XRD) analysis confirmed that no chemical interactions or new phases occurred. Differential Scanning Calorimetry (DSC) findings revealed an enhancement in PEG's latent heat of PEG from 214 J/g to 238.3 J/g (with 8 wt.% ZnO) and 257.7 J/g (with 12 wt.% ZnO). The thermal conductivity improved by 28.2% and 30.3%, respectively, while Thermogravimetric Analysis (TGA) demonstrated increased thermal stability. The addition of ZnO can improve the conductivity and thermal stability, while the role of SDBS is significant in increasing the latent heat, making this composite a potential candidate for Thermal Energy Storage system (TES) applications.

SYNTHESIS OF SINGLE-PHASE HYDROXYAPATITE POWDER FROM EGGSHELL WASTE VIA CO-PRECIPITATION METHOD AND ITS STRUCTURAL CHARACTERIZATION

Tue, 17 Jun 2025 00:00:00 +0100

This study aims to synthesize a single-phase hydroxyapatite powder using waste chicken eggshells as a calcium source via the co-precipitation method. The process focuses on optimizing calcination time and temperature to achieve high-purity hydroxyapatite. The co-precipitation procedure involved controlled pH adjustment and aging time, contributing to the formation of homogeneous particles. Chicken eggshells, predominantly composed of calcium carbonate (CaCO₃), were calcined at 1000°C for 15 hours to produce calcium oxide (CaO). The resulting CaO was then reacted with phosphate ions in an aqueous solution, followed by a calcination at 900°C for varying holding times of 5 and 10 hours. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis were conducted to evaluate phase composition, crystal size, and texture properties. The optimum condition was found at 900 °C for 10 h calcination, resulting in single-phase hydroxyapatite, a crystallite size of 220 nm, an average pore radius of 6.78 nm, a total pore volume of 0.02 cc/g, a surface area of 6.38 m²/g, and an average particle radius of 213.89 nm. These findings highlight the potential of this method for producing bioceramics with desirable properties for use in bone grafts and other biomedical materials.

LANDSLIDE AREA MAPPING IN DAMPIT SUBDISTRICT, MALANG DISTRICT, EAST JAVA PROVINCE USING SATELLITE IMAGERY OF GRAVITY DATA FOR DISASTER MITIGATION

Tue, 17 Jun 2025 00:00:00 +0100

Research using satellite imagery of gravity data has been conducted in the Dampit District, Malang Regency, East Java Province. This research was conducted to identify areas vulnerable to landslides. The results of this research can serve as a basis for the government to develop effective landslide disaster mitigation policies, thereby minimizing the losses incurred. The data used is TOPEX satellite gravity data in the form of Free Air Correction data, and supported by landslide vulnerable areas data from the InaRisk satellite. The research area is 23 km x 16 km with 2 km spacing between points and 184 measurement points. Furthermore, the research area is divided into four areas: Area A1, Area A2, Area A3, and Area A4. The residual anomaly value in the study area is between 82.7 mGal to 142.4 mGal. The residual anomalies are more variable due to the local nature of the anomalies. The correlation between the residual anomaly value and InaRisk satellite image data shows that Area A4 is the most vulnerable to landslides, especially if there is a trigger such as an earthquake. This is because Area A4 has a low-density value, a large fault, and is the contact area between the Mandalika Formation and Wuni Formation.

IMPLEMENTATION OF AAPM TG-218 FOR PATIENT SPECIFIC QUALITY ASSURANCE (PSQA) IN THE CASE OF THORACIC TARGET REGION USING IMRT RADIOTHERAPY TECHNIQUE WITH EPID aSi-1200

Wed, 02 Jul 2025 00:00:00 +0100

The implementation of Patient-Specific Quality Assurance (PSQA) is crucial for ensuring the accuracy and safety of Intensity-Modulated Radiation Therapy (IMRT). This study evaluates the application of AAPM TG-218 recommendations in PSQA for thoracic region treatment using the IMRT technique. The study compares two PSQA methods, Perpendicular Composite (PC) and Perpendicular Field-by-Field (PFF), using Electronic Portal Imaging Device (EPID). Measurements were conducted on 10 IMRT patients using a Varian TrueBeam Linac and Eclipse TPS. The Gamma Index (GI) analysis with criteria 3%/3 mm, 3%/2 mm, and 2%/2 mm was used to assess dose distribution accuracy. The results indicate that the average Gamma Passing Rate (GPR) for 3%/2 mm criteria exceeded 95%, which is appropriate with AAPM TG-218 standards. However, stricter criteria (2%/2 mm) did not reach the minimum recommended values. The study suggests that PSQA using EPID with the PFF method under rotational gantry conditions is the most suitable approach for thoracic IMRT treatment verification. The local standardization recommendations from the results of this study can be used as a reference for determining methodological standards in cases of the thoracic region in the IMRT technique to increase efficiency in clinical applications with similar PSQA dosimetry.

CHARACTERIZATION OF GEOTHERMAL POTENTIAL USING 2D MAGNETOTELLURIC INVERSION AT TELAGA TUJUH WARNA, LEBONG REGENCY, BENGKULU PROVINCE, INDONESIA

Tue, 29 Jul 2025 00:00:00 +0100

The Telaga Tujuh Warna area in Lebong Regency exhibits geothermal manifestations such as hot water, mud craters, and fumaroles. This research aims to characterize the geothermal potential using 2D Magnetotelluric (MT) inversion. Measurements were conducted with the ADU-07e Magnetotelluric device, involving a 16-hour measurement period. Data collection followed the sounding principle with three frequency levels: high (4096 Hz), medium (1024 Hz), and low (128 Hz), spaced approximately 500 meters apart. Analysis confirms the consistency between 1D and 2D resistivity models, generating a resistivity distribution cross-section. Key findings include: (1) a low-resistivity cap layer (20–40 Ω-m) at approximately 1 km depth; (2) a medium-resistivity reservoir (40–160 Ω-m) at depths of 1–2 km; (3) a high-resistivity geothermal resource (>300 Ω-m) at depths of 1–2.5 km; and (4) a zone with very low resistivity values (2–16 Ω-m) at depths less than 1 km, potentially indicating a fumarole emitting hot water vapor and gas through rock fractures. These findings aim to advance geothermal exploration in Lebong Regency and support Indonesia's renewable energy objectives.

INTEGRATING HIGH-RESOLUTION GRAVITY GRADIENTS AND 3D INVERSION MODELING TO DELINEATE MINERAL RESOURCES IN THE LEWA DISTRICT, EAST SUMBA, INDONESIA

Aprianus Raja, Jehunias Tanesib, Laura A. S. Lapono, Richard Lewerissa — Fri, 01 Aug 2025 00:00:00 +0100

Research in Lewa District, East Sumba Regency, Indonesia, aimed to identify mineral potential and clarify subsurface geological structures through gravity gradient analysis and 3D inversion modeling. This approach addresses the limitations of field gravity data in the study area. The gravity gradient method was chosen to delineate geological structure boundaries (such as formation contacts and faults) compared to conventional gravity methods and for processing global satellite data (GGMplus and EGM2008 derivatives of ERTM 2160) with limited measured data. Gravity gradient analysis, including vertical, horizontal gradient, and tilt angle, was applied to Complete Bouguer Anomaly data using 2D Fourier transformation. Gravity field correction in Lewa showed positive anomalies from volcanic basement rocks. The gradient analysis sharpened boundaries of anomalies linked to geological structures. Zero contours of vertical gradient and tilt angle defined structural boundaries, while peaks of horizontal gradient and tilt angle indicated metallic mineral sources. 3D gravity inversion modeling (density 2.22–2.97 g/cm³) showed rock intrusions at 215 meters depth, interpreted as key to mineralization formation. The 2D sections (A-A', B-B', C-C') contain Masu Formation volcanic rocks, with fault zones filled by Waikabubak Formation sedimentary rocks and silicified rocks from magma intrusion alteration. Fault systems were identified through vertical gradient extremes, representing contact formation. Highly positive contour values on the tilt angle map confirm the influence of the volcanic basement rock. Metal mineralization is closely related to tectonic activity and alteration from massive igneous intrusion. The integration of gravity gradient analysis and 3D inversion modeling has proven to be effective in mapping geological structures and identifying mineral prospects using limited data. These findings provide insights into the subsurface geology of Lewa and provide a basis for further mineral exploration in East Sumba.

ASSESSING CISANTI LAKE SEDIMENTS AS ENVIRONMENTAL QUALITY INDICATORS IN THE UPSTREAM OF THE CITARUM RIVER

Wed, 13 Aug 2025 00:00:00 +0100

Environmental conditions in aquatic ecosystems could change due to the entry of additional materials, such as heavy metals and magnetic minerals. These materials, referred to as anthropogenic materials, could be derived from human activities. The presence of the materials could affect the magnetic properties and heavy metals content of river water and sediments. We have analyzed magnetic susceptibility and heavy metal concentration in sediments collected from Cisanti Lake. Cisanti Lake is known as “zero kilometers” of the Citarum River. Using the level of heavy metals in sediments, we calculated and evaluated pollution indices in the form of Contamination Factor (CF), Geoaccumulation Index (Igeo), and Pollution Load Index (PLI). The results showed that the magnetic susceptibility of sediments (𝜒_𝐿𝐹) was in the range of 317.2 - 2274.9 (× 10^-8) m³kg^-1, inferring the dominance of ferrimagnetic minerals in sediments. Based on bivariate analysis of 𝜒_𝐿𝐹 and the calculated frequency-dependent magnetic susceptibility or c_FD(%), domain states of magnetic minerals are clustered at stable single domain (SSD)/multidomain (MD). Pollution indices of CF and Igeo showed that all sample points were contaminated by Cu at a considerable level. Moderate to significant contamination occurred in the studied area according to the PLI analysis. The positive strong correlation between 𝜒_𝐿𝐹 and PLI suggests that magnetic susceptibility serves as a proxy indicator of contamination.