Indonesian Physical Review

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

Ahmad Dhuha Habibullah — 2025-02-02

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

Uvia Ardina Zahira — 2025-02-06

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

Nur Afifah Zen — 2025-03-12

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

Harsano Jayadi — 2025-03-19

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.