Indonesian Physical Review

IDENTIFICATION OF AQUIFERS BASED ON THE VERTICAL ELECTRICAL SOUNDING (VES) METHOD SCHLUMBERGER CONFIGURATION CASE STUDY: PULAU BAAI KAMPUNG MELAYU SUB-DISTRICT, BENGKULU CITY, INDONESIA

Tegar Al Rafly — 2024-10-01

Investigation of the groundwater potential in the Pulau Baai area, Kampung Melayu Sub-district, Bengkulu City, must be carried out in such a way that the activities and needs of the people in the area can be fulfilled and the needs of the population in the area can be met. This study aims to determine the status of groundwater using the Schlumberger configuration geoelectric method. Measurements were made using a resistivity meter, and the results for each configuration depended on changes in resistivity. Measurements for each configuration depend on changes in resistivity at depth, the vertical direction (sounding), and the lateral direction (mapping), so hydrogeological analysis in this activity aims to get the maximum use of groundwater / underground water in aquifers for raw water needs. The dominant rock structures in the study area are clay, alluvium, siltstone, and sandstone, as well as some rocks with suitable porosity and permeability as water carriers, such as sand and gravel. However, what appears to have considerable potential is that groundwater is found at depths of 4-53 meters in VES 1, VES 2, VES 3, VES 5, and VES 10. The results of the analysis show that the location of the Pulau Baai, Kampung Melayu Sub-district, Bengkulu City Priority Utilization Area is within the groundwater storage area, so it can be used to meet the raw water needs of the study area.

PHOTOINACTIVATION OF CANDIDA ALBICANS BIOFILM WITH GREEN LASER MEDIATED BY THE PAPAYA LEAF EXTRACT CHLOROPHYLL

Rismayani Abdullah — 2024-10-21

This study aims to activate the effectiveness of Photodynamic Inactivation (PDI) as an antibacterial agent by using a green laser and papaya leaf chlorophyll extract to prevent Candida albicans cell death. Papaya leaf extract chlorophyll is known to have potential as a photosensitizer (PS) through its antimicrobial properties and ability to absorb optimal light photons at a wavelength range of 405–680 nm. Activation of chlorophyll molecules with appropriate light produces Reactive Oxygen Species (ROS), which are toxic to pathogenic microbes such as Candida albicans. The research method involves using PDI with a green laser light source and chlorophyll extract on Candida albicans biofilms. Four main treatment groups were applied, negative control (C-), positive controls with 10% (C1+) and 15% chlorophyll (C2+), irradiation for 60, 120, 180, 240, and 300 seconds (L1–L5), and combinations of irradiation with chlorophyll (L1F1–L5F2, where F1 for 10% chlorophyll and F2 for 15% chlorophyll), with measurements performed three times for each treatment. Living Candida albicans cells were detected using the XTT assay staining method. The results showed a significant decrease in activity in all treatment groups. Maximum activity was achieved in the L5F1 and L5F2 treatment groups with inactivation of 80% (p<0.05) and 83% (p<0.05), respectively. This study concludes that high papaya leaf extract chlorophyll concentrations combined with a green laser effectively inhibit Candida albicans biofilm.

DESIGN AND SELECTION OF PADDLE MATERIALS FOR HIGH-LEVEL ROWING COMPETITION APPLICATIONS USING MULTI-CRITERIA DECISION ANALYSIS

Aditya Eka Nurfitrah — 2024-11-11

The study evaluated a variety of material alternatives including wood, bamboo, carbon fiber reinforced polymer (CFRP), and ceramics for use in high-performance paddleboard. The selection process considers factors such as strength, density, cost, and durability with a focus on the most relevant material criteria for the product. The weighted addition method is used to evaluate and rank several alternative materials that have been selected based on these criteria. Wood and bamboo are chosen for their sustainability, CFRP for their superior strength-to-weight ratio, and ceramics for their resistance to extreme conditions. The study found that CFRP had the highest score of around 85.40 due to its superior strength and lightweight. The framework proposed in this study could provide tools for rowing teams to optimize paddle materials so that they offer the potential for increased speed and performance in the competition.

DESIGN AND BUILD A MICROCONTROLLER BASED DIP COATER TOOL WITH AN AUTOMATIC CALIBRATION SYSTEM

Nizar Rizki Rahman — 2024-11-11

Dip-coating is essential for coating materials evenly, as imperfections like macropores can impact material properties. This project presents a digitally controlled dip-coating tool that manages withdrawal speed, immersion time, and speed via a microcontroller with an automatic calibration system. Employing a stepper motor and mathematical formula approach, the tool achieves high precision by automatically adjusting dipping parameters, with key metrics including resolution-dependent V_l, calibration speed V_pc and calibration targets t_pc,and S_c.The system reaches stable calibration at V_ms= V_pc. ensuring rapid, accurate calibration and minimizing errors to 0-2% across 20 to 650 steps. Additionally, the tool’s energy-efficient design consumes less power than other dip-coating systems, providing both durability and accuracy.

SYNTHESIS AND CHARACTERIZATION OF ZEOLITES FROM COAL FLY ASH WASTE

Mitra Fitriani — 2024-11-14

South Sumatra had coal production through PT Bukit Asam Tbk, which had coal production since 1950. Tanjung Enim Steam Power Plant (PLTU) is the largest coal ash producer because coal is the primary fuel. Coal combustion by-products include coal fly ash (CFA) and coal bottom ash (CBA). The current utilization of the CFA Tanjung Enim Steam Power Plant is for a cement mixture of PT Semen Baturaja and planting media. This work attempts to optimize zeolite synthesis from CFA by examining the effects of hydrothermal duration on reducing coal waste. This research studies the effect of hydrothermal time with time variations of 5, 12, and 24 on the morphology and phase of zeolite obtained. CFA from the Tanjung Enim Steam Power Plant contains SiO₂ and Al₂O₃, which account for 47.7% and 28.7% of the total composition, respectively. The SEM characterization result shows that the synthesized zeolite forms aggregates with a particle size of about 8-15 μm. Based on XRD characterization of CFA hydrothermal time of 5 hours, the dominant phase is the gibbsite phase, but there is a sodalite phase. The 12-hour hydrothermal time showed the formation of quartz, gibbsite, and sodalite phases. The 24-hour hydrothermal time shows that the dominant phase is sodalite, but there are gibbsite and quartz phases. The peak of the quartz phase decreases the longer the hydrothermal time. In this study, the duration of the hydrothermal process affects the formation of the zeolite phase.

DESIGN OF A PORTABLE PHOTOTHERAPY UNIT FOR HYPERBILIRUBINEMIA USING SURFACE MOUNTING DEVICE LIGHT EMITTING DIODES

Sri Herwiningsih — 2024-11-14

Hyperbilirubinemia is a condition of a high bilirubin level in newborns causing a yellowish color on newborns’ skin and sclera. One of the treatment methods commonly used for hyperbilirubinemia is phototherapy in which newborns are exposed to visible light, especially within the green-blue spectrum. This study aimed to design a prototype of a portable phototherapy unit for newborns with hyperbilirubinemia. The phototherapy unit was designed by using a Surface Mounting Device Light Emitting Diode (SMD LED) with a wavelength of 400-520 nm as a light source which was attached to a fabric inside a box made of acrylic. The SMD LED strips were arranged with a spacing of 5 cm between the SMD LED arrays. The system was equipped with a monitoring system using SHT11 as a temperature and humidity sensor as well as a timer to adjust the duration of exposure and the LCD. The prototype was tested by irradiating various concentrations of artificial bilirubin solutions with a blue light produced by the phototherapy unit. The results show that the system can reduce the concentration of artificial bilirubin solution with an average reduction of 30.8%. The system shows the potential to be used as a portable phototherapy unit, further improvement on the efficacy, safety and comfort of the unit is required.

GREEN SYNTHESIS OF TIO2 USING ALOE VERA FOR PHOTODEGRADATION IN SASIRANGAN WASTE

Noor Asyiah — 2024-11-20

Green synthesis of TiO₂ has been successfully carried out using aloe vera. Aloe vera extract was mixed with TiCl₄ while heated to obtain TiO₂ powder. The FTIR spectrum showed a peak at 487.67 cm-¹ corresponding to the Ti-O-Ti functional group, which indicates the formation of TiO₂ particles. The XRD results showed that the TiO₂ crystals were in the anatase phase. SEM images show that the particles tend to be spherical in shape as in the anatase phase. With the Scherer equation, the size of the TiO₂ crystal yielded was around 2.3 nm in diameter. The UV-vis spectrophotometer results showed the blue shift of absorption peak at 368 nm or band gap energy of 3.37 eV. A thin layer of TiO₂ was made by using the slip casting method. These thin films were applied to methylene blue and sasirangan waste samples for photodegradation tests. The exposure times used were 15, 30, 45, 60, and 75 minutes. The results showed photodegradation of 38.9 % and 4.5 %, respectively, for methylene blue and sasirangan waste.

ABRASION INVESTIGATION USING SHEAR WAVE VELOCITY AND POISSON’S RATIO APPROACHES IN URAI VILLAGE NORTH BENGKULU REGENCY

Tiara Sesilia — 2024-11-21

The coastal areas of North Bengkulu Regency, particularly Urai Village, have been severely impacted by widespread abrasion, posing a high risk of coastal erosion within Bengkulu Province. This study aims to assess the extent of coastal degradation and support disaster mitigation efforts by investigating the properties and structure of rocks using geophysical methods, specifically the Multichannel Analysis of Surface Waves (MASW). The research focuses on determining shear wave velocity (Vs) to model the rock layers and produce a stratigraphic profile with a minimal misfit value. The obtained Vs30 values, ranging from 146 m/s to 603 m/s, indicate that the coastal region primarily comprises soft soils, which are highly susceptible to deformation, including abrasion. These findings provide essential data for understanding the underlying causes of coastal erosion and contribute to future disaster mitigation strategies.

OPTIMIZING THE CARBONIZATION TEMPERATURE OF WATER HYACINTH BIOCHAR BY PROXIMATE ANALYSIS USING RESPONSE SURFACE METHODOLOGY

Wenny Maulina — 2024-11-22

Water hyacinth is a locally available biomass with the potential to be converted into biochar, serving as a renewable energy source. In this report, response surface methodology (RSM) was employed to optimize the carbonization temperature during the preparation of water hyacinth biochar. Water hyacinth was carbonized in a furnace at varied temperatures (400 °C, 500 °C, 600 °C) for 90 minutes. Characterization of the biochar derived from water hyacinth by proximate analysis was determined, including moisture content, ash content, volatile matter, fixed carbon, and calorific value. The results of the biochar before optimization indicated that moisture content and volatile matter decreased with increasing carbonization temperature, while ash content, fixed carbon, and calorific value increased. After optimization, the proximate analysis of the biochar was determined, with the optimal carbonization temperature found to be 533.54 °C. At this temperature, the optimal moisture content was 6.50%, ash content was 25.53%, volatile matter was 24.80%, and fixed carbon was 43,16%. These findings demonstrate the feasibility of using RSM to optimize the preparation conditions of water hyacinth biochar.

DIAGENETIC STUDY BASED ON PETROGRAPHY: IMPLICATIONS FOR SANDSTONE POROSITY OF THE PEUNASU FORMATION, PULAU NASI, ACEH

Dina Gunarsih — 2024-12-03

Diagenetic studies observe the process of changing sedimentary deposits into sedimentary rocks. This study is critical because it relates to the quality of rock porosity, which can be filled by fluid. The analysis of the Peunasu Formation is interesting because previous researchers considered that the Tertiary sedimentary rocks in the Northwest Aceh Basin are equivalent to rock units in the petroleum system in the North Sumatra Basin and Mergui Basin. Meanwhile, studies on the Peunasu Formation, a tertiary sedimentary rock, still need to be completed. Therefore, this study was carried out to determine the characteristics and diagenetic processes in the sandstone of the Peunasu Formation. The method used is petrographic observation, which identifies the composition of rocks along with textures such as grain size, roundness, sorting, grain contact, and porosity. The results are that the Peunasu Formation sandstone is classified as sublitharenite, lithic greywacke, and litharenite. The diagenetic regime is mesogenesis. In the mesogenesis stage, the sandstone of the Peunasu Formation experiences compaction, cementation, and dissolution. The porosity of the Peunasu Formation sandstone, as determined by the percentage of pores, exhibits a range of 0.5% to 16.8%, categorizing it as ranging from negligible to moderate. Compaction reduces the intergranular porosity, while the dissolution of grains contributes to the formation of secondary porosity.

DESIGN OF AN AUTOMATIC PENDULUM VELOCITY MEASURING DEVICE USING LIGHT SENSORS

Rima Fitria Adiati — 2024-12-09

The instantaneous velocity of an object is the rate of change of its position over an infinitesimally small-time interval, making direct measurement with tools like stopwatches impractical. Using two LDR sensors paired with an Arduino, it is possible to measure such small-time intervals effectively. Understanding the maximum velocity of a mathematical pendulum is critical for distinguishing between harmonic and non-harmonic oscillations. To validate the accuracy of the sensor-Arduino system, several experiments were conducted, including comparisons between Arduino measurements and those obtained from a movie tracker, as well as variations in sensor separation distances, initial oscillation angles, and pendulum rope lengths. Results showed a high level of agreement between Arduino and movie tracker measurements for pendulum crossing times. Additionally, the sensor-Arduino system successfully differentiated the effects of varying each parameter while holding others constant. The system demonstrated an accuracy of 97.86% for velocity measurements at a release angle of 5°, with an average recorded velocity of 23.350 m/s. These findings confirm the sensor-Arduino system's capability to reliably measure the velocity of a mathematical pendulum.

MODELING INFLUENCE OF URBAN SPRAWL ON URBAN HEAT ISLAND (UHI) ACTIVITY IN KOLAKA REGENCY

Satriawan Nadhrotal Atsidiqi — 2024-12-13

The expansion of urban areas into rural regions, known as Urban Sprawl, contributes to the Urban Heat Island (UHI) phenomenon, where urban areas exhibit higher temperatures than their rural counterparts. Kolaka Regency is an area with significant potential for Urban Sprawl and subsequent UHI activity. Therefore, it is essential to investigate the impact of Urban Sprawl on UHI in the Kolaka region. This study simulates these changes using the Weather Research and Forecasting (WRF) model, incorporating land cover data from the Geospatial Information Agency (BIG) with four urban schemes: SLUCM, BEM, and the default non-UCM/land cover. The simulation also includes the Kolaka 2042 development map for Urban Sprawl projections. Simulations were conducted over 48 non-rainfall events across 12 months. The results indicated that the WRF BIG-BEM model demonstrated the highest verification accuracy and the lowest errors, with a MAPE of 4.70%, CRMSE of 1.06°C, and a correlation coefficient of 87.62%. Including BIG land cover and the BEM urban scheme enhanced the model's performance, with a MAPE of 17.92%, CRMSE of 10.11%, and a correlation improvement of 3.18%. The UHI effect predominantly ranged from -2.0 to 2.5°C, with the highest values observed in the Pomalaa mining area and central Kolaka Regency. The UHI effect was most pronounced from evening to morning, peaking during the night and early morning hours, with increased intensity during the dry season from July to September. Regression analysis revealed a trend of increasing UHI following Urban Sprawl activity, with a trend rate of 0.91°C. The R-squared value of 96.69% indicates that Urban Sprawl activity accounted for 96.69% of the UHI intensity in Kolaka, while other unexamined variables influenced 3.31%.

COMPARATIVE BEHAVIOR OF MAGNETIC IRON OXIDE NANOPARTICLES (MIONS) VIA MECHANICAL AND CHEMICAL ROUTES

Ilham Dias Fajariman — 2024-12-17

This study successfully synthesized Magnetic Iron Oxide Nanoparticles (MIONs) through two different processes, namely mechanical synthesis (MIONs – M) and chemical synthesis (MIONs – N). The synthesized samples were characterized using X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Vibrating Sample Magnetometer (VSM) to determine the elemental composition, morphology, structure, and magnetization of the samples. XRF analysis revealed that iron (Fe) dominated both samples, with concentrations reaching 93.91% for MIONs – M and 89.91% for MIONs – N. SEM morphological analysis showed that the MIONs tended to be spherical and experienced agglomeration, with particle size distribution around 120 nm for MIONs – M and 30 nm for MIONs – N. XRD data indicated that both samples exhibited a cubic spinel Fe₃O₄ phase, consistent with the AMCSD 0000945 model data. Using the refinement method and Debye-Scherrer equation, the crystallite size and density of MIONs – M were found to be larger than MIONs – N. This correlates with VSM data analysis, where the saturation magnetization of MIONs – M (49.51 emu/g) was greater than that of MIONs – N (26.54 emu/g). These results provide important insights into the characteristics of MIONs and their implications for technological and industrial applications.