Water rockets provide a simple yet effective physics experiment integrating mechanics, fluid dynamics, and kinematics. Their performance is influenced by initial air pressure and water volume fraction, which can be quantitatively analyzed using numerical simulation. This study investigates the effects of varying pressure (300–500 kPa) and water volume fraction (f = 0.10–0.60) on thrust profiles and maximum altitude, with analysis covering four distinct phases. The method involves formulating nonlinear differential models for each phase, followed by numerical simulations using the fourth order Runge Kutta (RK4) method with an optimized time step (Δt = 0.001 s) to ensure convergence and computational efficiency. Results show that higher pressures increase peak thrust and maximum altitude, but shorten the duration of water thrust. An optimal water volume fraction of f ≈ 0.20–0.30 provides a balance between thrust intensity and duration to achieve maximum altitude. Further experiments with variations in bottle structure and aerodynamic parameters are recommended.

Abstract. This study aims to investigate the potential of durian husk fiber (Durio zibethinus) as the base material for environmentally friendly acoustic panels. The samples were prepared as composites with a fixed composition ratio of durian husk fiber and epoxy resin at 2:1, and with varying thicknesses of 1 cm, 2 cm, 3 cm, and 4 cm. The sound absorption coefficient was measured using the impedance tube method based on ISO 10534-2 in the frequency range of 200–1600 Hz. The results showed that all samples demonstrated good acoustic performance. The 3 cm thick sample provided the best performance with the highest absorption coefficient value of 0.98 at a frequency of 1600 Hz. Increasing the thickness to 4 cm reduced the material's acoustic performance, indicating an optimal thickness limit for sound absorption. This study indicates that durian husk fiber has high potential as an alternative acoustic material that is effective and sustainable, especially for absorbing noise in mid to high frequency ranges.

The horizontal gradient method is a widely used qualitative approach for enhancing the interpretation of gravity anomaly data. This method is particularly effective in delineating lithological boundaries between rock units with contrasting densities, especially where contacts are horizontally aligned. Horizontal gradient calculations are performed by partially differentiating gravity data with respect to its horizontal position. This method was applied to gravity data of Weh Island, the westernmost part of Indonesia, to delineate fault zones and lithological boundaries in the region. The results of the study show that this method can effectively identify rock formations on Weh Island, such as the boundary between coral reef limestone and pyroclastic flow units, as well as tuff sandstone areas and surrounding rocks, including volcanic kulam units and volcanic pumice rocks. Applying the horizontal gradient method to gravity data on Weh Island produced maps that clearly outline rock formations. Combining these with geological maps shows a northwest–southeast trend aligned with the main strike of the Seulimuem Fault, which crosses the island. The results from analyzing horizontal derivatives offer key insights for studies of lithology, faulting, and subsurface layers in complex geological regions like Weh Island.

MAPbI3 perovskite material is a leading candidate for third-generation solar cells because it has high absorbance and a suitable band gap. However, efficiency and stability remain major issues. In this study, phenethylammonium iodide (PEAI) doping will be performed on the optical properties and energy gap of MAPbI3 perovskite material. The Perovskit layers were fabricated by two-step spin coating method which is known to be effective in producing controlled and homogeneous thin layers. Characterization of the coating was carried out by UV-Vis spectroscopy to obtain absorbance spectrum data, and then analyzed using the Tauc Plot method to obtain the energy Gap value. The results show that the addition of PEAI can increase the intensity of absorption in the visible light region and cause a blue shift at the absorption edge. The energy Gap value increased after doping from 1.61 eV in the pure sample without doping to 1.68 eV for the highest doping concentration. This indicates that PEAI doping plays a role in modifying the energy band structure and improving the optical characteristics of Perovskit layers. This study shows that PEAI doping is a promising approach to improving the optical performance of perovskite layers in solar cell applications.

In molecular radiotherapy, dosimetry accuracy is highly dependent on the calculation of the Time-Integrated Activity Coefficient (TIAC), as recommended by the Medical Internal Radiation Dose (MIRD). The accuracy of the TIAC value is obtained using data fitting in the form of a mathematical function model. The fitting function represents the pharmacokinetic parameters of the radiopharmaceutical in the form of radiopharmaceutical activity, physical decay, and biological decay. The aim of this study is to estimate parameters of activity and biological decay rate constants based on biokinetic data (activity fraction) against time. Fitting of biokinetic data was performed using the sum of exponential (SoE) monoexponential function with a MATLAB® 2020b simulation to estimate the activity parameter (Ao) and the biological decay rate constant parameter (λ₀) of the population. A simplified linearity regression test was also performed to estimate the biological decay rate constant parameter (λ) individuallly for each patient. The results of the fitting obtained the values of Ao and λ₀ for each organ as follows:liver (Ao= 0.290 and λ₀= 0.02 h-1), right parotid (Ao= 0.05 and λ₀= 0.02 h-1), left parotid (Ao= 0.05 and λ₀= 0.02 h-1), right kidney (Ao= 0.45 and λ₀= 0.02 h-1), left kidney (Ao= 0.39 and λ₀= 0.02 h-1) and bladder (Ao= 0.09 and λ₀= 0.03 h-1). From the linear regression test, the λ values from the fastest to the latest decay range were obtained for the organs: right kidney (0.015-0.036 h-1), liver (0.009-0.032 h-1), left kidney (0.017-0.032 h-1), right parotid gland (0.014-0.035 h-1), left parotid gland (0.014-0.034 h-1) and bladder (0.010-0.047 h-1). Based on this result, it can be concluded that using a monoexponential function to fit and perform a simple linear regression test is effective in estimating parameters in both the population and individuals.

This article presents a comprehensive review of recent advancements in perovskite-based solar cells, focusing on material structures, optical properties, and electronic characteristics. The objective is to identify the potential and technical challenges affecting device performance and long-term stability. A systematic literature study was conducted using peer-reviewed articles published between 2021 and 2025, retrieved from international databased index. The review highlights that variations in perovskite composition, including all-inorganic and hybrid types, significantly affect optical absorption and photoluminescence, as well as device stability. Furthermore, fabrication methods such as spin coating, vapor deposition, and blade coating have a direct impact on power conversion efficiency (PCE), short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF). Blade coating yielded the highest reported PCE of 27.8% and Voc up to 1.9 V, while vapor deposition achieved Jsc up to 25.7 mA/cm² and FF of 76.8%. This review concludes that the advancement of perovskite solar cells should focus on integrated strategies in material design and deposition techniques to ensure high efficiency and long-term operational reliability.

Hydroxyapatite is one of the candidate medical materials as bone and tooth replacement (implant). In this study, the synthesis and characterisation of hydroxyapatite from clamshells (Anadara granosa) with variations in sintering resistance time were successfully carried out. The purpose of this research is to synthesise hydroxyapatite from clamshells and find out how the effect of variations in sintering resistance time on crystal size and degree of crystallinity of hydroxyapatite. The source of calcium oxide (CaO) used in the synthesis of hydroxyapatite comes from blood cockle shells powder (Anadara granosa), after first the blood cockle shells is calcined at 1000⁰C with a holding time of 5 hours. The hydroxyapatite synthesis process uses a solid state reaction method with a sintering temperature of 900⁰C with a variation of holding time of 2 hours, 4 hours and 6 hours to determine the formation of hydroxyapatite. This process has successfully formed calcium oxide (CaO) compounds based on characterisation with XRF (X-Ray Fluorosence) and XRD (X-Ray Diffractometer). Based on the XRD test results, it is known that hydroxyapatite has been successfully synthesized from clamshells. The characterisation results show that the variation of sintering resistance time affects the degree of crystallinity and crystal size of hydroxyapatite, which are 45.70% - 68.49% and 49.9nm - 55.37 nm, respectively.

Machine learning has rapidly emerged as an effective system in various fields, including materials science, due to its ability to efficiently uncover complex patterns from big data. This research aims to develop a machine learning-based semiconductor electrical conductivity prediction system integrated with solid state physics theory. In the context of electronic material technology development, the ability to predict the electrical properties of materials before the synthesis process is crucial for improving efficiency and accuracy in material design. This study employs a qualitative descriptive method to create a machine learning-based system and qualitatively describe the research results. The dataset is obtained from various literature and previous experiments, with physical parameters such as crystal structure, band gap, and density. The machine learning model used is the random forest algorithm. Evaluation results show that the system can classify materials based on their electrical conductivity properties with high accuracy. Materials such as GaAs, Ge, and Si are identified as potential candidates for electronic device design. The integration of solid-state physics theory into this system enhances the physical and statistical validity of predictions. This research demonstrates that a machine learning approach based on physical principles can be an effective solution for future semiconductor material engineering.

CT-Scan examination in medical diagnostics produces higher radiation compared to conventional X-Ray, especially for certain clinical conditions that require additional contrast media that contribute to higher radiation energy absorbed by the tissue. Contrast media are generally iodine-based which has a high density and absorbs more X-rays, thus increasing the HU value. This study aims to determine the effect of contrast media on Hounsfield Unit (HU), Computed Tomography Dose Index (CTDI), and Dose Length Product (DLP) values to support the determination of Typical Dose Value (NDT). This study uses an experimental quantitative approach by comparing CT-Scan examination data before and after administration of contrast media in a number of patients. HU values are measured in the main blood vessels, while CTDI and DLP were obtained directly from the CT Scanner console. The study sample consisted of 30 abdominal patients and 26 head patients for NDT analysis, including 10 abdominal patients and 10 head patients each used to detect changes in HU values. The results show that the administration of contrast media in CT examinations of the abdomen and head causes a significant increase in Hounsfield Unit (HU) values, namely from 43,53 to 290,58 for the abdomen and from 35,98 to 67,65 for the head. In addition, there is an increase in the Typical Dose Value (NDT) after the use of contrast. The recorded radiation dose parameters are of 5,05 mGy and DLP of 118,13 mGy cm for the abdomen, and of 49,35 mGy and DLP of 1108,30 mGy cm for the head, all of which remain below the Dose Reference Level (DRL) limit. These results confirm that contrast media not only improve image quality by increasing Hounsfield Units (HU), but also affect the amount of radiation dose received by patients. Therefore, optimal scanning parameter settings are needed to achieve a balance between diagnostic image quality and radiation safety.

This research aims to analyze the high level thinking abilities (HOTS) of class VII students on temperature and heat subject seen from the learning environment. The HOTS measured includes three aspects: analysis (C4), evaluation (C5), and creation (C6). This research also discusses how specific and general learning environments influence student understanding. This type of research is descriptive qualitative, involving 60 students of SMP Negeri 1 Lhokseumawe, consisting of 30 students from special learning environments and 30 students from general learning environments. Data was obtained through a HOTS-based 9-question written test, interviews and observations. The results show that students from special learning environments have better HOTS abilities, with the highest score on creation (C6) of 45.60%. The low ability of students from general learning environments is due to a lack of support, such as additional tutoring. Schools are advised to provide support programs to improve students' abilities