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

Fetronela Rambu Bobu, Marselina Theresia Djue Tea , Pujianti Bejahida Donuata — 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.