Indonesian Physical Review https://ipr.unram.ac.id/index.php/ipr <p><span id="result_box" lang="en"><strong>Acredited SINTA 2</strong></span></p> <p><span id="result_box" lang="en">Indonesian Physical Review is a peer review journal which is managed and published by Physics Departement, Faculty of Mathematics and Natural Sciences, Universitas Mataram. This journal is published periodically three times a year, in <strong>January, May and September</strong>.</span></p> en-US <p>Authors who publish with Indonesian Physical Review Journal, agree to the following terms:<br /><br /></p><ol><li>Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a <a href="https://creativecommons.org/licenses/by-sa/4.0/">Creative Commons Attribution-ShareAlike 4.0 International Licence (CC BY SA-4.0)</a>. This license allows authors to use all articles, data sets, graphics, and appendices in data mining applications, search engines, web sites, blogs, and other platforms by providing an appropriate reference. The journal allows the author(s) to hold the copyright without restrictions and will retain publishing rights without restrictions.</li><li>Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgment of its initial publication in <a href="/index.php/ipr">Indonesian Physical Review Journal</a>.</li><li>Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See <a href="http://opcit.eprints.org/oacitation-biblio.html">The Effect of Open Access</a>).</li></ol> [email protected] (Lily Maysari Angraini) [email protected] (I Gusti Ngurah Yudi Handayana) Sun, 02 Feb 2025 11:38:23 +0000 OJS 3.2.1.4 http://blogs.law.harvard.edu/tech/rss 60 LEVERAGING THE UBIQUITOUS GPS SENSOR ON THE SMARTPHONES FOR ACCESSIBLE LAND SURVEYING https://ipr.unram.ac.id/index.php/ipr/article/view/361 <h3><em>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.</em></h3> Ahmad Dhuha Habibullah, Elfi Yuliza, Ismail Fahmy Almadi, Yazid Ismi Intara, Riska Ekawita Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/361 Sun, 02 Feb 2025 00:00:00 +0000 IMPACT OF ZN-DOPPED ON SNEDDS/ZNXFE3-XO4 FORMULATION ON THEIR CRYSTAL STRUCTURE AND ANTIOXIDANT PERFORMANCE https://ipr.unram.ac.id/index.php/ipr/article/view/428 <p><em>Self-Nano-Emulsifying Drug Delivery System </em><em>(SNEDDS)/Zn<sub>x</sub>Fe<sub>3-x</sub>O<sub>4</sub></em><em> has been successfully formulated through the synthesis of </em><em>Zn<sub>x</sub>Fe<sub>3-x</sub>O<sub>4</sub> </em><em>by the coprecipitation method and </em><em>SNEDDS/Zn<sub>x</sub>Fe<sub>3-x</sub>O<sub>4</sub></em><em> by the sonication method. This study is focused on the effect of Zn doping on the crystal structure and antioxidant performance of</em> <em>Zn<sub>x</sub>Fe<sub>3-x</sub>O<sub>4</sub></em><em> nanoparticles. </em><em>Zn<sub>x</sub>Fe<sub>3-x</sub>O<sub>4</sub></em><em> samples were characterized using FTIR and XRD to determine the functional groups and structure of the sample, respectively. </em><em>SNEDDS/Zn<sub>x</sub>Fe<sub>3-x</sub>O<sub>4 </sub></em><em>samples 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 </em><em>Zn<sub>x</sub>Fe<sub>3-x</sub>O<sub>4 </sub></em><em>sample showed the emergence of Zn-O and Fe-O functional groups in the wave number range of 825-869 cm<sup>-1</sup> and 560-594 cm<sup>-1</sup>, respectively. This indicates that Zn<sup>2+</sup> doping was successfully synthesized and shifted the Fe<sup>3+</sup> ion. The IR spectrum also shows that the higher the concentration of Zn<sup>2+</sup> ions, the more significant the change in absorption intensity, indicating that more molecules absorb light at wave numbers of 825-869 cm<sup>-1</sup>. The XRD characterization results show that the </em><em>Zn<sub>x</sub>Fe<sub>3-x</sub>O<sub>4 </sub></em><em>nanoparticle structure is an inverse cubic spinel occupying the Fd3m crystal group. Based on the analysis of XRD data, the higher the concentration of Zn<sup>2+</sup> doping, the smaller the size of the </em><em>Zn<sub>x</sub>Fe<sub>3-x</sub>O<sub>4 </sub></em><em>nanoparticles produced. The diffraction peak of the sample on the 311 plane shifts towards a smaller angle due to the effectiveness of Zn<sup>2+</sup> ion doping, shifting the Fe<sup>3+</sup> ion because the radius of the Zn<sup>2+</sup> ion is larger than the Fe<sup>3+</sup> one. The antioxidant performance analysis of SNEDDS/ZnxFe3-xO4 showed inhibition potential ranging from 11% to 15%, increasing with higher Zn²</em><em>⁺</em><em> concentrations.</em></p> Uvia Ardina Zahira, Nadiya Miftachul Chusna, Ahmad Taufiq, Sunaryono Sunaryono Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/428 Thu, 06 Feb 2025 00:00:00 +0000 UTILIZATION OF ULTRASONIC WAVE IN THE PRODUCTION OF REDUCED GRAPHENE OXIDE FROM COCONUT SHELL BIOMASS: ECO-FRIENDLY AND SUSTAINABLE APPROACH https://ipr.unram.ac.id/index.php/ipr/article/view/434 <p><em>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.</em></p> Nur Afifah Zen, Indah Permatasari, Irmayatul Hikmah, Prasetyo Yuliantoro, Dina Rahmawati Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/434 Wed, 12 Mar 2025 00:00:00 +0000 A NON-LINEAR HYPOCENTER LOCALIZATION ALONG THE ACTIVE PALU-KORO FAULT: A CASE STUDY CENTRAL SULAWESI https://ipr.unram.ac.id/index.php/ipr/article/view/418 <p><em>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.</em></p> Harsano Jayadi, Moh. Dahlan Th. Musa, Gazali Rachman, Icha Untari Meidji, Muhammad Fawzy Ismullah Massinai, Dwa Desa Warnana Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/418 Wed, 19 Mar 2025 00:00:00 +0000 CORROSION RESISTANCE OF PANI/POLYMORPHIC-ZRO2 MODIFIED EPOXY PAINT IN HIGH SALINITY ENVIRONMENT https://ipr.unram.ac.id/index.php/ipr/article/view/446 <p><em>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/ZrO<sub>2</sub>) to 0.3988 mpy (with PANI/m-ZrO<sub>2</sub>), 0.0364 mpy (with PANI/t-ZrO<sub>2</sub>) and 0.0212 mpy (with PANI/tm-ZrO<sub>2</sub>). 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.</em></p> Munaji Munaji, Rizki Dwi Ardika, Nanang Sufiadi Ahmad, Albet Eka Pratama, Ahmad Rifai, Alfandy Kurnia Azam, Triwikantoro Triwikantoro Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/446 Tue, 29 Apr 2025 00:00:00 +0100 DEVELOPMENT OF LOW-COST OPTICAL SENSOR-BASED DEVICE FOR REAL-TIME MICROALGAE CONCENTRATION MEASUREMENT https://ipr.unram.ac.id/index.php/ipr/article/view/473 <h3><em>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.</em></h3> Heriyanto Syafutra, Erus Rustami, Stephanie Claudia, Safrina Dyah Hardiningtyas, Supriyanto Supriyanto, Mahfuddin Zuhri Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/473 Tue, 06 May 2025 00:00:00 +0100 ANALYSIS OF LINES FORMATION PRODUCED BY ELECTROHYDRODYNAMIC JET PRINTING FOR TERAHERTZ (THZ) METAMATERIALS FABRICATION https://ipr.unram.ac.id/index.php/ipr/article/view/433 <p><em>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.</em></p> Ayodya Pradhipta Tenggara, Hadi Teguh Yudistira, Brian Godwin Mtei, Doyoung Byun Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/433 Tue, 06 May 2025 00:00:00 +0100 SYNTHESIS OF ZINC OXIDE/CHITOSAN/CHITRONELLA ESSENTIAL OIL HYBRID NANOPARTICLES USING SOL-GEL METHOD: STRUCTURAL AND OPTICAL PROPERTIES https://ipr.unram.ac.id/index.php/ipr/article/view/419 <p><em>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.</em></p> Budi Astuti, Nur 'Ainiyyah Hasni, Ari Sulistiyo Rini, Dimas Mohamad Ayubi, Agus Yulianto, Masturi Masturi, Teguh Darsono, Putut Marwoto, Sugianto Sugianto, Suriani Abu Bakar, Fatiatun Fatiatun Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/419 Thu, 08 May 2025 00:00:00 +0100 THE POTENTIAL OF FALOAK BARK (STERCULIA QUADRIFIDA R.BR.) as an ACTIVATED CARBON PRODUCT THROUGH PHYSICAL-CHEMICAL ACTIVATION METHOD https://ipr.unram.ac.id/index.php/ipr/article/view/448 <h3><em>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 </em><em> (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.</em></h3> Fetronela Rambu Bobu, Marselina Theresia Djue Tea , Pujianti Bejahida Donuata, Matius Stefanus Batu Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/448 Thu, 08 May 2025 00:00:00 +0100 DELINEATING RESISTIVITY VALUES OF POTENTIAL GEOTHERMAL AREAS ALONG THE BOGOR FAULT USING 2D MAGNETOTELLURIC INVERSION https://ipr.unram.ac.id/index.php/ipr/article/view/431 <p><em>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.</em></p> Debi Hardiansa, M Farid, Arif Ismul Hadi, Andre Rahmat Al-Ansory, Hana Raihana, Nurul 'Ilmi Rahmawati Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/431 Thu, 08 May 2025 00:00:00 +0100 LABORATORY MODEL LANDSLIDE MONITORING SYSTEM USING INTERNET OF THINGS (IOT) TECHNOLOGY https://ipr.unram.ac.id/index.php/ipr/article/view/479 <p><em>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 (R<sup>2</sup> = 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 m<sup>3</sup>/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.</em></p> Fredrik Manuhutu, Matheus Souisa, Sisca M. Sapulete Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/479 Wed, 21 May 2025 00:00:00 +0100 IDENTIFICATION OF SEAWATER INTRUSION DISTRIBUTION PATTERNS USING 2D ELECTRICAL RESISTIVITY TOMOGRAPHY (ERT) DATA IN SEMARANG, INDONESIA https://ipr.unram.ac.id/index.php/ipr/article/view/461 <p><em>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 &lt; 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.</em></p> Eko Minarto, Amanda Rizky Utami, Lina Handayani, Yayat Sudrajat Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/461 Wed, 21 May 2025 00:00:00 +0100 ECO FRIENDLY CITRIC ACID-ASSISTED SOL-GEL SYNTHESIS OF HIGH-PURITY NANO SILICA FROM DIENG GEOTHERMAL SLAG: CHARACTERIZATION AND OPTIMIZATION METHOD https://ipr.unram.ac.id/index.php/ipr/article/view/486 <p><em>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.</em></p> David C Birawidha, Azwar Manaf, Widi Astuti, Amru Daulay, Tri Haryono, Yuliana Sari, Suprihatin Suprihatin Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/486 Fri, 23 May 2025 00:00:00 +0100 REFORMULATION OF GEOMETRIC OPTICS WITHIN THE FRAMEWORK OF ABELIAN U(1) GAUGE THEORY: A NOVEL APPROACH TO UNDERSTANDING LIGHT PROPAGATION https://ipr.unram.ac.id/index.php/ipr/article/view/464 <p><em>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.</em></p> Adrianus Inu Natalisanto, Sri Purwaningsih Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/464 Sat, 24 May 2025 00:00:00 +0100 HAWKING TEMPERATURE IN SCHWARZSCHILD BLACK HOLES WITH QUINTESSENCE DARK ENERGY https://ipr.unram.ac.id/index.php/ipr/article/view/454 <h3><em>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.</em></h3> Agustina Widiyani, Ana Novita Sari, Ikah Ning Prasetiowati Permanasari, Eko Satria, Azrul Sulaiman Karim Pohan, Weni Ayu Puja Kesuma, Indra Pardede, Agus Suroso Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/454 Sun, 25 May 2025 00:00:00 +0100 ANALYSIS OF AGRICULTURAL SOIL CONDITIONS 20 YEARS POST-TSUNAMI USING RESISTIVITY AND SOIL PH METHODS https://ipr.unram.ac.id/index.php/ipr/article/view/463 <p><em>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.</em></p> Rahiel Adiannur, Amsir Amsir, Zakia Masrurah, Marwan Marwan, Mustapha Adejo Mohammed Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/463 Wed, 28 May 2025 00:00:00 +0100 MAPPING LEACHATE CONTAMINATION USING RESISTIVITY GEOELECTRIC METHOD AT TPA KEBON KONGOK, WEST LOMBOK REGENCY, WEST NUSA TENGGARA PROVINCE https://ipr.unram.ac.id/index.php/ipr/article/view/447 <p><em>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. </em></p> Muhammad Hisyam Ramadhan Ramadhan, Mochamad Arief Budihardjo, Kasiyati Kasiyati Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/447 Thu, 29 May 2025 00:00:00 +0100 EVALUATING SURFACE TEMPERATURE VARIABILITIES AND CLIMATE EXTREMES IN THE DIENG PLATEAU OVER THREE DECADES https://ipr.unram.ac.id/index.php/ipr/article/view/493 <h3><em>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 &lt; 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.</em></h3> Imma Redha Nugraheni, Rista Hernandi Virgianto, Aries Kristianto, Deni Septiadi, Hapsoro Agung Nugroho, Ita Soegiarto, Fachri Radjab Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/493 Thu, 29 May 2025 00:00:00 +0100 INFLUENCE OF COMPOSITION AND LYOPHILIZATION TIME ON PHYSICAL PROPERTIES OF HA/Cs/Coll/ HYDROXYPROPYL METHYLCELLULOSE BIOCOMPOSITES FOR BONE SCAFFOLDS https://ipr.unram.ac.id/index.php/ipr/article/view/474 <p><em>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. </em></p> Dyah Purnaning, Hurnah Hurnah, Ahmad Taufik S, Susi Rahayu, Dian W. Kurniawidi, Kasnawi Al Hadi Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/474 Fri, 30 May 2025 00:00:00 +0100 ANALYSIS OF LANDSLIDE DISASTER POTENTIAL IN MEULABOH AREA, WEST ACEH REGENCY, ACEH USING RESISTIVITY AND GEOSPATIAL METHODS https://ipr.unram.ac.id/index.php/ipr/article/view/469 <p><em>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</em><em> 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.</em></p> Lasin Agnia, Amsir Amsir, Marwan Marwan, Zakia Masrurah, Agus Hari Pramana Copyright (c) 2025 https://creativecommons.org/licenses/by-nc-sa/4.0 https://ipr.unram.ac.id/index.php/ipr/article/view/469 Fri, 30 May 2025 00:00:00 +0100