Indonesian Physical Review

LEVERAGING THE UBIQUITOUS GPS SENSOR ON THE SMARTPHONES FOR ACCESSIBLE LAND SURVEYING

Sun, 02 Feb 2025 00:00:00 +0000

The Global Positioning System (GPS) is an essential tool in land surveying. GPS has become an alternative method of surveying that requires less manpower and less time. However, GPS devices are still expensive to buy, especially for students. On the other hand, almost every student has a smartphone with a built-in GPS sensor, so this GPS is certainly accessible to everyone with a smartphone. This study used a smartphone's GPS to conduct land surveying at the campus of Bengkulu University. This smartphone’s GPS was used to track various parameters such as coordinates, elevation, and distance between two or more points to calculate the area within the study area. The innovative method of using the built-in GPS sensor in smartphones will provide convenience for users and introduce simplified open-source software for the land measurement process. The measurement was calibrated using a conventional roll meter to verify the linear error by comparing the two measurements between the smartphone’s GPS and roll meter. The smartphone’s GPS reading was logged using GPS Waypoints and My Tracks, free Android applications on the Google Play store. This study's average error in measurements obtained using GPS on smartphones was 3.02%. This value is sufficient for the initial stage of low-cost land surveys and falls within ideal conditions for GPS measurements. Therefore, this article emphasizes the potential of smartphone GPS to optimize techniques in education and scientific investigations.

IMPACT OF ZN-DOPPED ON SNEDDS/ZNXFE3-XO4 FORMULATION ON THEIR CRYSTAL STRUCTURE AND ANTIOXIDANT PERFORMANCE

Thu, 06 Feb 2025 00:00:00 +0000

Self-Nano-Emulsifying Drug Delivery System (SNEDDS)/Zn_xFe_3-xO₄ has been successfully formulated through the synthesis of Zn_xFe_3-xO₄ by the coprecipitation method and SNEDDS/Zn_xFe_3-xO₄ by the sonication method. This study is focused on the effect of Zn doping on the crystal structure and antioxidant performance of Zn_xFe_3-xO₄ nanoparticles. Zn_xFe_3-xO₄ samples were characterized using FTIR and XRD to determine the functional groups and structure of the sample, respectively. SNEDDS/Zn_xFe_3-xO₄samples were characterized using FTIR and Antioxidants with the DPPH method to determine the functional groups and antioxidants in the sample, respectively. The FTIR characterization results of the Zn_xFe_3-xO₄sample showed the emergence of Zn-O and Fe-O functional groups in the wave number range of 825-869 cm^-1 and 560-594 cm^-1, respectively. This indicates that Zn²⁺ doping was successfully synthesized and shifted the Fe³⁺ ion. The IR spectrum also shows that the higher the concentration of Zn²⁺ ions, the more significant the change in absorption intensity, indicating that more molecules absorb light at wave numbers of 825-869 cm^-1. The XRD characterization results show that the Zn_xFe_3-xO₄nanoparticle structure is an inverse cubic spinel occupying the Fd3m crystal group. Based on the analysis of XRD data, the higher the concentration of Zn²⁺ doping, the smaller the size of the Zn_xFe_3-xO₄nanoparticles produced. The diffraction peak of the sample on the 311 plane shifts towards a smaller angle due to the effectiveness of Zn²⁺ ion doping, shifting the Fe³⁺ ion because the radius of the Zn²⁺ ion is larger than the Fe³⁺ one. The antioxidant performance analysis of SNEDDS/ZnxFe3-xO4 showed inhibition potential ranging from 11% to 15%, increasing with higher Zn²⁺ concentrations.

UTILIZATION OF ULTRASONIC WAVE IN THE PRODUCTION OF REDUCED GRAPHENE OXIDE FROM COCONUT SHELL BIOMASS: ECO-FRIENDLY AND SUSTAINABLE APPROACH

Wed, 12 Mar 2025 00:00:00 +0000

The production of reduced graphene oxide (rGO) using environmentally friendly methods remains a challenge in the development of sustainable energy storage materials. This study explores the utilization of ultrasonic waves in the production of rGO from coconut shell biomass as a green and cost-effective approach. Ultrasonic treatment for 30 minutes (UB-30) resulted in a graphene sheet morphology, enhanced carbon content, and reduced oxygen functional groups on rGO. Electrochemical characterization showed that the specific capacitance of the ultrasonically treated rGO (UB-30) reached 789 F/g at a scan rate of 10 mV/s, demonstrating competitive electrochemical performance for supercapacitor applications. The use of coconut shell biomass as a precursor offers an eco-friendly solution, while the application of ultrasonication enables higher production efficiency with lower energy consumption. These findings contribute significantly to the development of electrode materials for supercapacitors and sustainable energy storage systems.

A NON-LINEAR HYPOCENTER LOCALIZATION ALONG THE ACTIVE PALU-KORO FAULT: A CASE STUDY CENTRAL SULAWESI

Wed, 19 Mar 2025 00:00:00 +0000

The Central Sulawesi region is prone to earthquakes, as evidenced by its complex geological structure. Several plates and active fault movements in the vicinity cause this situation. One of the active faults that often causes earthquakes is the Palu-Koro active fault. The city of Palu is one of the areas passing through the Palu-Koro fault. The danger of this earthquake occurrence can be ascertained and assessed using a suitable earthquake location. Within the scope of our investigation, we used a non-linear approach to predict the hypocenter site in the vicinity of the Palu-Koro fault that is active. This Method use oct-tree importance sampling algorithm to generate spatial hypocenter locations. Using the AK135 minimal seismic velocity model, we manually re-picked the arrival times of wave P-waves and S-waves arrival timings of 3,852 and 3,690, respectively, collected by 24 BMKG observation sites from January 2011 to December 2015, utilizing the minimal 1D seismic velocity model from AK135. We employed criteria to ascertain the event's location, including a minimum of four stations exhibiting a distinct beginning of P and S wave arrivals, with a magnitude of at least 3Mw and an average depth ranging from 10 to 20 km. The outcomes of seismic event location identification exhibit improved clustering with inversion, revealing a zero-centered Gaussian distribution, where more time discrepancies, both positive and negative, correspond to increased estimating mistakes. According to this research, the Palu-Koro active fault line's primary shallow seismic zone is the most prominent feature in the area and confirms the existence of active land faults that cause earthquake events by conducting a process of determining a locally updated 1D velocity model that will be used to determine a more precise relocation of the hypocenter used to interpret the subsurface model of the research area.

CORROSION RESISTANCE OF PANI/POLYMORPHIC-ZRO2 MODIFIED EPOXY PAINT IN HIGH SALINITY ENVIRONMENT

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

Corrosion in high-salinity environments remains a major concern in maintaining the durability and performance of metallic infrastructure. The use of conductive polymers and ceramic nanoparticles, such as polyaniline (PANI) and zirconia (ZrO₂), has emerged as a promising strategy to improve the corrosion resistance of protective coatings. This study aims to evaluate the effect of ZrO₂ polymorphic phases—tetragonal (t-ZrO₂), monoclinic (m-ZrO₂), and a mixture of tetragonal–monoclinic (tm-ZrO₂)—on the corrosion protection performance of PANI/ZrO₂-modified epoxy coatings applied on ST42 steel. The coatings were applied using spray coating. Compositions of ZrO₂ were varied at 2.5%, 5%, 7.5%, and 10% by weight. To simulate a marine environment, corrosion resistance was assessed using Tafel plot measurements in a 3.5% NaCl solution at room temperature. The results revealed that coatings containing t-ZrO₂ and tm-ZrO₂ phases exhibited significantly lower corrosion rates than those with m-ZrO₂. At 7.5% composition, the addition of ZrO₂ reduced the corrosion rate from 0.6710 mpy (without PANI/ZrO₂) to 0.3988 mpy (with PANI/m-ZrO₂), 0.0364 mpy (with PANI/t-ZrO₂) and 0.0212 mpy (with PANI/tm-ZrO₂). These findings highlight the critical role of ZrO₂ phase composition in improving coating performance. Incorporating t-ZrO₂ and tm-ZrO₂ into epoxy coatings presents a promising pathway to enhance corrosion resistance, offering valuable potential for applications in aggressive saline environments.

DEVELOPMENT OF LOW-COST OPTICAL SENSOR-BASED DEVICE FOR REAL-TIME MICROALGAE CONCENTRATION MEASUREMENT

Tue, 06 May 2025 00:00:00 +0100

Conventional methods for measuring microalgae concentration in water require several steps and must be carried out in the laboratory. These measurements are usually performed by counting microalgae filaments under an optical microscope using the Sedgewick Rafter Counting (SRC) method or by spectroscopy, utilizing light absorption by microalgae's chlorophyll. In this study, we propose an innovative and portable spectroscopic device for real-time measurement of microalgae concentration by integrating a light-dependent resistor (LDR) sensor and a microcontroller-based processing unit. The microalgae used in this study were Spirulina, a filamentous microalga from the class Cyanophyceae. The SRC method was used as a reference for measuring Spirulina concentration. UV-Vis spectroscopy data showed that the absorption of chlorophyll a and b was in the range of 400 - 450 nm. The absorption coefficients obtained from the UV-Vis absorbance vs. concentration relationship were in good agreement with those obtained from the logarithmic light intensity vs. concentration relationship across all tested predictive models. We confirmed that the emission spectrum of the LED used was aligned with the dominant absorption of Spirulina chlorophyll, ensuring accurate optical detection of microalgae concentration. The developed device demonstrated rapid estimation of microalgae concentration, with an average accuracy of more than 75%. This study showed that a portable and low-cost microalgae concentration measurement system can be developed using optical sensors and microcontrollers as an alternative to laboratory-based measurements. In addition, the designed device can be integrated with Internet of Things (IoT) platforms, enabling real-time monitoring of environmental conditions for applications such as water quality assessment, aquaculture, and biofuel production.

ANALYSIS OF LINES FORMATION PRODUCED BY ELECTROHYDRODYNAMIC JET PRINTING FOR TERAHERTZ (THZ) METAMATERIALS FABRICATION

Ayodya Pradhipta Tenggara, Hadi Teguh Yudistira, Brian Godwin Mtei, Doyoung Byun — Tue, 06 May 2025 00:00:00 +0100

Electrohydrodynamic (EHD) jet printing has revolutionized semiconductor manufacturing technologies to fabricate high resolution materials pattens (metal, dielectric, or semiconductors) in small size. This technology can reduce excessive materials usage in conventional semiconductor lithographic technologies, such as photolithography or electron beam lithography, so that it can be categorized as a green manufacturing technology. EHD jet printing has a capability to fabricate resonant terahertz metamaterial. Resonant terahertz metamaterial contains metal structures in micrometer sizes patterned on dielectric substrate. The metal structures are arranged periodically to generate resonances in specific frequencies, which are beneficial for several applications, such as biosensing, chemical sensing, and terahertz optical modulators for future communication devices. To make a high resolution and repeatable structures, EHD jet printing faces two main problems, i.e. the drop coalescence problem and the charge problem. The charging problem can be solved by removal of substrate charges using ionizer. However, the drop coalescence problem is a type of complex problem that needs to be studied and optimized systematically to produce repeatable and reliable terahertz resonant metamaterial structures, which is electric split ring resonator (ESRR). The objective of this research is to investigate to the formation stability of dots and lines produced by the EHD jet printing. We used EHD jet printing through the Drop on Demand (DoD) method to deposit droplets from metal nanoparticle ink with various volumes on dielectric substrates with different thickness. Several parameters were investigated, i.e. the droplet volume, the droplet spacing, and the substrate thickness. The results showed that by increasing the deposited droplet volumes and decreasing the substrate thickness, the stability of line formation was improved. Moreover, the stability analysis of line formation revealed that by using the bigger volume, the minimum printing speed to make uniform line was decreased, because the bigger droplet volume gave smaller contact angle. The results also showed that the uniformity of metamaterials patterns could be improved by using the smaller width.

SYNTHESIS OF ZINC OXIDE/CHITOSAN/CHITRONELLA ESSENTIAL OIL HYBRID NANOPARTICLES USING SOL-GEL METHOD: STRUCTURAL AND OPTICAL PROPERTIES

Thu, 08 May 2025 00:00:00 +0100

Due to their properties, ZnO nanoparticles have recently been used as an additive material in active food packaging. ZnO has a wide band gap of about 3.37 eV, making it effectively used under UV light. However, ZnO nanoparticles are not effectively used under visible light. This study successfully synthesized ZnO-Chitosan-Citronella Essential Oil hybrid nanoparticles using sol-gel methods. Adding chitosan and citronella essential oil will affect nanoparticles' structural and optical properties. The structural, morphological, and optical properties of characterized hybrid nanoparticles were studied using X-ray diffraction (XRD) and FTIR, scanning electron microscope (SEM), energy dispersive X-ray (EDX), and UV-Vis spectroscopy. From XRD, it was obtained that the ZnO nanoparticles produced have a hexagonal wurtzite crystal structure with angles of 2q = 31.76°, 34.48°, 36.30° which are crystal planes with orientations (100), (002), and (101), as well as several other peaks for planes (102), (110), (103), (200) and (112) with a crystallinity index value of 86.5390%, and crystallite size of 8.87nm and 7.5335 nm. From FTIR Characterization, Zn=O functional groups were also obtained at wave numbers 657 and 475 cm-1. The morphology of ZnO nanoparticles from SEM spectroscopy shows a spherical shape with agglomeration, and the composition of the components Zn, O, and N elements is found, which come from chitosan materials. Furthermore, from the UV-Vis spectroscopy characterization, it was obtained that the absorption occurred in the 380-600 nm region with a band gap energy of 3.25 eV (using the tauc plot method), which was slightly different from the empirical results of 3.30 eV. The results show potential future studies of hybrid nanoparticles, such as additive materials in active food packaging.

THE POTENTIAL OF FALOAK BARK (STERCULIA QUADRIFIDA R.BR.) as an ACTIVATED CARBON PRODUCT THROUGH PHYSICAL-CHEMICAL ACTIVATION METHOD

Thu, 08 May 2025 00:00:00 +0100

Faloak is a plant species native to the East Nusa Tenggara region and Australia, widely used by the local community in NTT as an herbal medicine, particularly in treating liver disease, digestive disorders, and fatigue. However, this study presents a new application by analyzing its physical-chemical properties and evaluating its effectiveness in the synthesis of activated carbon. This study aims to explore and analyze the potential of Faloak bark as a source of activated carbon, which has not been examined in previous research. This research uses a quantitative approach by conducting controlled laboratory experiments to measure and analyze the variation in activator concentration on the water and ash content of activated carbon. The research applied the physical-chemical activation method. The physical activation process involved heating at temperatures ranging from 250°C to 450°C, while chemical activation was conducted using ZnCl₂ and NaOH at concentrations of 1 N, 2 N, and 3 N. This method was selected to determine the optimal conditions for converting Faloak bark into activated carbon, focusing on temperature and chemical activators. The findings indicate that the optimum temperature for activated carbon formation is 300°C. Additionally, tests using chemical activators showed that Faloak bark performs best with a 2 N NaOH solution, as evidenced by ash and water contents of 0.03% and 0.65%, respectively. Functional group analysis through FTIR testing identified the presence of (hydroxyl), aromatic C=C, and carbonyl C=O groups, further supporting the potential of Faloak bark as a viable material for activated carbon production. The findings suggest that Faloak bark has significant potential to be developed into an activated carbon product.

DELINEATING RESISTIVITY VALUES OF POTENTIAL GEOTHERMAL AREAS ALONG THE BOGOR FAULT USING 2D MAGNETOTELLURIC INVERSION

Thu, 08 May 2025 00:00:00 +0100

Kepahiang Regency, located in an active fault zone, has great geothermal potential with an estimated capacity of up to 154 MW(e), making it a strategic renewable energy source to be developed. This research discusses the geothermal potential in the Kabawetan area, Kepahiang, Bengkulu. The main objective of this research is to evaluate the potential of geothermal resources around the Bogor segment by analyzing the subsurface structure using the Magnetotelluric inversion method and 2D resistivity modeling, in order to identify prospective geothermal reservoir zones. It can evaluate the potential of geothermal reservoirs in Kepahiang. The method used is the Magnetotelluric method, which utilizes the Earth's natural electromagnetic field to determine the distribution of resistivity in the subsurface. The results of 2D modeling with the MT method show potential zones associated with variations in subsurface thermal conditions and the presence of conductive clay minerals with resistivity values between 0.14-1 Ωm. These minerals are thought to be associated with the overburden (reservoir) of the geothermal system that has a depth of 2-4 km. The subsurface layer containing hot water and steam originating from heat emitted from the earth's core with a resistivity value of 2.5-45 Ωm at a depth of 1-4 km is thought to be caprock in the geothermal system, a resistivity value of 120-800 Ωm is thought to be hot rock with a depth between 1.5-10 km. It is estimated that there is a type of andesite rock that has been fractured as a reservoir of geothermal fluid. The findings of this research are expected to contribute to renewable energy as an alternative energy in the future, not only for energy needs but also for regional economic development through tourism and to support sustainable governance.

LABORATORY MODEL LANDSLIDE MONITORING SYSTEM USING INTERNET OF THINGS (IOT) TECHNOLOGY

Fredrik Manuhutu, Matheus Souisa, Sisca M. Sapulete — Wed, 21 May 2025 00:00:00 +0100

A landslide disaster is one of the natural disasters that has a detrimental impact on society. This impact can be avoided if the community knows the signs of landslides and gets a warning that a landslide will occur. Therefore, this study aims to design an laboratory landslide warning monitoring system based on Internet of Things (IoT) technology. Landslide monitoring using a tilt sensor connected to a web communication network. Before data testing, IoT sensor calibration was carried out. The calibration results showed a coefficient of determination (R² = 0.9967), so that this sensor system can be used as a smart sensor in monitoring landslides. In the data acquisition process, the IoT system sends data in real time which is received by the computer via the internet network. The web communication network displays the results in the form of a 2D profile in real time, namely a graph of the slope angle against time. To confirm the web monitoring data, a computer programming language is used to display a 3D profile of the slip plane. The study results show that IoT technology can monitor landslides and the presence of artificial rain in real time with a reading of the soil displacement sensor of 32.4°. At this angle, a landslide occurs until it deposits under the foot of the slope, with a landslide mass deposition rate of 0.0012 m³/s. The designed IoT system is portable and permanent and can monitor landslides. This system can be developed more widely in areas prone to landslides for smart communities and can be used as a disaster prevention and mitigation movement in arranging spatial planning based on disaster mitigation. This research can advance our understanding of landslide monitoring dynamics using web-based IoT systems, providing important insights for mitigation strategies and future research.

IDENTIFICATION OF SEAWATER INTRUSION DISTRIBUTION PATTERNS USING 2D ELECTRICAL RESISTIVITY TOMOGRAPHY (ERT) DATA IN SEMARANG, INDONESIA

Eko Minarto, Amanda Rizky Utami, Lina Handayani, Yayat Sudrajat — Wed, 21 May 2025 00:00:00 +0100

Various environmental problems exist in the northern coast area of Semarang, Indonesia, including land subsidence, tidal flooding, increased chloride content in several monitoring wells, and salinity in resident wells. These issues indicate a decrease in groundwater quality caused by seawater intrusion. Sanitary and health issues have a significant impact on many environmental issues, including decreased soil fertility and building damage. The problem of seawater intrusion can be identified by the geoelectric resistivity method (multi-electrode dipole-dipole configuration). The aim of this research is to detect the presence of seawater intrusion in groundwater zones and determine the extent of its distribution to the mainland. Data collection was carried out along the western canal flood. The data obtained distribution of subsurface apparent resistivity values. Interpretation of the 2D cross-sectional model identified as a seawater intrusion zone with low resistivity (𝜌 < 3 Ω m) ranging from 0-2.600 m. Thick in the northward with a depth of 30-60 m and becomes thin in the south at 2.600 m. At a trajectory 2.600-7.000 m low resistivity is still found in a local spot. The result of the 2D cross-section model inversion shows very good result. Predicted data is quite close to the observed data shown by an average small RMS 2.37% - 4.11%. And shown by a fast convergence curve. The coastal area of Semarang is also found to be made up of five layers: alluvial soft clay, silt clay, sandy clay, granule sand, and coarse sand. These results fit with the well log data around the research area. Estimates of the distribution of seawater intrusion in more detail to the mainland need to be further investigated using other geophysical methods and testing of monitoring wells or resident wells around the research area for more accurate results.

ECO FRIENDLY CITRIC ACID-ASSISTED SOL-GEL SYNTHESIS OF HIGH-PURITY NANO SILICA FROM DIENG GEOTHERMAL SLAG: CHARACTERIZATION AND OPTIMIZATION METHOD

Fri, 23 May 2025 00:00:00 +0100

Geothermal slag is a by-product of the geothermal power generation process, but its added value is minimal. With a silica content of up to 70%, geothermal slag has potential as a secondary silicon source for battery silicon anode precursors. Usually, the synthesis of nano-silica was carried out through the sol-gel method, in which HCl is usually used as a modifier to regulate the physical and chemical properties of the material. But in this study chose citric acid for modifier agent because it is more environmentally friendly. The challenge of using citric acid is the formation of carbon-based salts that can cause silica blackening if not washed well. Therefore, optimization was done by adjusting the pH to produce high-purity nano-silica. The sol-gel process was carried out by adding 10% NaOH and 5N Citric Acid, with varying pH base conditions from 8 to 11. XRF analysis results showed the highest purity at pH 8. Impurities were still visible based on XRD data, and the formation of nanoparticles was confirmed through morphological analysis using FESEM and TEM where the average particle size formed is between 55 nm.

REFORMULATION OF GEOMETRIC OPTICS WITHIN THE FRAMEWORK OF ABELIAN U(1) GAUGE THEORY: A NOVEL APPROACH TO UNDERSTANDING LIGHT PROPAGATION

Adrianus Inu Natalisanto, Sri Purwaningsih — Sat, 24 May 2025 00:00:00 +0100

This study introduces a reformulation of geometrical optics through the framework of Abelian U(1) gauge theory. By leveraging this novel approach, phase equations are derived, serving as the cornerstone for determining the trajectories of light rays. The proposed formulation is validated through simulations of light propagation in diverse scenarios, including homogeneous refractive index media, vacuum, anisotropic materials, and optical metamaterials. These results underscore the versatility and predictive power of this gauge-theoretic approach, opening new avenues for exploring and modeling complex optical phenomena.

HAWKING TEMPERATURE IN SCHWARZSCHILD BLACK HOLES WITH QUINTESSENCE DARK ENERGY

Sun, 25 May 2025 00:00:00 +0100

Black holes are thermodynamic objects that emit Hawking radiation near the event horizon of a black hole according to the theory of quantum gravity in curved space-time. This radiation is manifested as the temperature of a black hole, known as the Hawking temperature. According to black hole thermodynamics, the black hole horizon area corresponds to the entropy. The increase in the horizon area is predicted due to the influence of dark energy, which can push the horizon of the black hole away from its center, thus significantly affecting the radiation of the black hole. Here, we investigate the Hawking temperature of the Schwarzschild black hole under the effect of quintessence dark energy. The results show that the increase in quintessence reduces the horizon radius of the black hole and lowers its Hawking temperature, highlighting the direct relationship between dark energy and black hole dynamics.

ANALYSIS OF AGRICULTURAL SOIL CONDITIONS 20 YEARS POST-TSUNAMI USING RESISTIVITY AND SOIL PH METHODS

Wed, 28 May 2025 00:00:00 +0100

The tsunami that struck Aceh in 2004 caused significant damage to agricultural land, altering soil properties and affecting productivity. Mon Ikeun Village was one of the most affected areas in the Lhoknga Subdistrict of Aceh Besar Regency. As an agricultural area vulnerable to soil salinization, it faced reduced soil quality, fertility, and nutrient availability risks, which could significantly decrease crop productivity. Therefore, assessing the current condition of agricultural soils is essential to determine whether recovery has occurred or if contamination persists. This research investigates the condition of agricultural soils two decades after the tsunami by analyzing resistivity and soil pH measurements. The resistivity data were collected using a SuperSting R8 device with a Wenner configuration and subsequently processed with IPI2WIN. The pH was determined with a Hanna HI 991001 pH Meter. The results reveal that the affected soils present resistivity values between 9.06 Ωm and 131 Ωm, indicating compositions of sandy clay and sand layers. Soil pH ranges from 4.9 to 6.2, indicating slightly acidic to near-neutral conditions, suitable for agriculture. These results indicate a substantial recovery in soil conditions, especially when compared to a control site in a non-affected area with similar land characteristics. This reinforces the interpretation that the tsunami’s impact has diminished over time. This recovery is likely influenced by natural processes such as leaching of contaminants through rainfall. This integrated approach effectively evaluates long-term changes in agricultural soil affected by the tsunami. However, to obtain a clearer understanding of the soil recovery process, future studies could include additional measurements such as soil nutrient analysis, electrical conductivity, or salinity levels to offer more detailed insights.

MAPPING LEACHATE CONTAMINATION USING RESISTIVITY GEOELECTRIC METHOD AT TPA KEBON KONGOK, WEST LOMBOK REGENCY, WEST NUSA TENGGARA PROVINCE

Muhammad Hisyam Ramadhan Ramadhan, Mochamad Arief Budihardjo, Kasiyati Kasiyati — Thu, 29 May 2025 00:00:00 +0100

TPA Kebon Kongok is one of the Final Processing Sites in Indonesia that uses a sanitary landfill system. The limited availability of land and the increasing height of the waste pile that has been dumped during the TPA operation period and the discovery of leachate puddles at several points in the TPA area are problems that need to be addressed immediately so as not to disturb the environmental ecosystem and society. The purpose of this research is to determine the depth of leachate pollution in the subsurface and map the leachate distribution pattern around the TPA Kebon Kongok area. This research was conducted using the resistivity geoelectric method with a 2-D Wenner configuration in 10 lines and the Self Potential (SP) method with an area 132,732 m² and 138 data point. Based on data analysis, it is found that the layer indicated as leachate has a resistivity value of 0.143-4.71 Ωm. Based on the results of the SP analysis, it is known that the accumulated leachate streams are interpreted to have relatively lower self-potential values with anomalous values of -100 mV to -40 mV. Low potential values were found in the northwest to southeast of the study site, while relatively high potential values were found in the southern part of the study site. The direction of leachate distribution in various directions is due to the fact that the study area has different elevations and the subsurface layer is composed of layers that easily drain liquids, which are indicated as sand layers. This research is expected to be a consideration for the management of TPA Kebon Kongok in taking mitigation steps from leachate pollution.

EVALUATING SURFACE TEMPERATURE VARIABILITIES AND CLIMATE EXTREMES IN THE DIENG PLATEAU OVER THREE DECADES

Thu, 29 May 2025 00:00:00 +0100

This study examines long-term surface temperature variability and climate extremes in the Dieng Plateau, Central Java, from 1991 to 2022. Despite its tropical location, the region’s unique high-altitude microclimate, with frequent frost events, has raised concerns for local agriculture, particularly potato farming. However, limited observational data has constrained in-depth assessments. To address this, we used bias-corrected ERA5 reanalysis data, calibrated using hourly observations from an Automatic Weather Station (AWS) installed in 2021. The analysis focused on climatological trends and temperature-related extreme indices following the Expert Team on Climate Change Detection and Indices (ETCCDI) framework. Our findings indicate seasonal patterns in diurnal temperatures, with JJA (June–August) exhibiting the greatest variability and the lowest night time temperatures, conditions favorable to frost formation. Among the extreme indices, warmest night temperatures (TNx) increased significantly at a rate of 0.017°C/year (p < 0.01), while coldest night temperatures (TNn) showed a slight but significant decline. The frequency of warm nights (TN90p) rose by 0.242 days/month, while cold nights (TN10p) decreased by 0.161 days/month. Meanwhile, trends for warm days (TX90p), cold days (TX10p), and cold spell duration (CSDI) were statistically insignificant. These results highlight the plateau’s sensitivity to night time warming and the potential risk of climate-driven shifts in frost occurrence. The combination of high-resolution reanalysis data and extreme indices offers valuable insight into microclimate behavior in tropical highlands, with direct implications for frost risk management and climate adaptation strategies in vulnerable agricultural zones.

INFLUENCE OF COMPOSITION AND LYOPHILIZATION TIME ON PHYSICAL PROPERTIES OF HA/Cs/Coll/ HYDROXYPROPYL METHYLCELLULOSE BIOCOMPOSITES FOR BONE SCAFFOLDS

Fri, 30 May 2025 00:00:00 +0100

Biomaterial implants are one of the alternatives to replace damaged organs in the body system temporarily (scaffolding) or permanently. Bone biomaterial implants can be obtained through the manufacture of HA/Cs/Coll (HA/Cs/Coll) biocompositeses with the addition of Hydroxypropyl Methylcellulose (HPMC) matrix. The objective is to evaluate how variations in material composition and lyophilization time affect the physical properties of the biocomposites, including density, compressive strength, Young’s modulus, and surface morphology. The manufacture of biocomposites uses the mechanical thermal method for mixing materials and the freeze drying method for the biocomposites drying process. Composition ratios of HA:Cs/Coll were varied at 3:7, 5:5, and 7:3, while lyophilization durations were set at 24, 48, and 72 hours. Characterizations were performed through density measurements, mechanical testing using a Tensilon machine, and surface morphology analysis using a digital microscope. The results showed that the comparison of biocomposites with a ratio of 7:3 had the highest density of 0.150 gr/cm³, compressive strength of 0.046 MPa, and young modulus of 0.3 MPa. Meanwhile, the biocomposites that was lyophilized for 48 hours showed the best balance between a density of 0.145 gr/cm³, a compressive strength of 0.08 MPa, and a young modulus of 0.17 MPa. Morphological analysis revealed improved porosity and surface uniformity with longer freeze-drying times. Based on this, the resulting HA/Cs/Coll biocompositese has potential as an implant material but further research is needed to improve its mechanical properties by increasing the concentration of the binder, namely HPMC.

ANALYSIS OF LANDSLIDE DISASTER POTENTIAL IN MEULABOH AREA, WEST ACEH REGENCY, ACEH USING RESISTIVITY AND GEOSPATIAL METHODS

Lasin Agnia, Amsir Amsir, Marwan Marwan, Zakia Masrurah, Agus Hari Pramana — Fri, 30 May 2025 00:00:00 +0100

Meulaboh, in West Aceh Regency, is one of the areas with potential for landslides. The goal of this research is to identify soil conditions that could lead to landslides based on resistivity data, as well as to analyze the distribution of landslide potential using geospatial data. This research provides benefits to various stakeholders, including the government. It contributes to improved disaster mitigation planning, reduced risk of losses, and the selection of appropriate materials to construct more disaster-resilient infrastructure. The research methods used are 2D resistivity and geospatial methods with weighted overlay analysis. Based on the processing results of 2D resistivity data from profiles 1 and 2, the study area is characterized by silt, sand, and sandstone. The resistivity values of the material in profile 1, identified for silt, range between 1 and 119 Ω.m at depths of 2-59 meters. For sand, the resistivity values range between 120-225 Ω.m at 2-61 meters depths. Sandstone has resistivity values that range between 226-500 Ω.m at depths of 3-62 meters. The resistivity values of the material in profile 2, identified for silt, range between 1-119 Ω.m at depths of 1.5-60 meters. For sand, the resistivity values range between 120-225 Ω.m at 9-59 meters depths. Sandstone has resistivity values that range between 226-500 Ω.m at depths of 15-39.4 meters. The presence of silt (1-119 Ω.m) increases the potential for landslides due to its cohesive nature. Based on the weighted overlay analysis processing results, the study area has a moderate potential for landslides. The study area has characteristics such as a gentle to steep slope (8-45%), a high rainfall rate (2500-3000 mm/yr), a lithology consisting of rocks from the Tutut Formation, including silt, sand, and a small amount of conglomerate, and land that is used for plantations and rice fields.