Vol. 57 No. 1 (2025)

Monsoon variability plays a pivotal role in Malaysia

Three radiation detection tools were employed to assess natural radiation levels in Mamuju Regency, West Sulawesi, Indonesia. These tools comprised the NaI(Tl) Scintillator, the Geiger Muller Counter (GMC), and the Electronic Personal Dosimeter (EPD). The NaI(Tl) Scintillator and GMC measured ambient dose equivalent (H*(10)), while the EPD exclusively gauged personal dose equivalent (Hp(10)). A total of 75 measuring points were designated for assessment. Results from H*(10) measurements indicated that the GMC recorded an average H*(10) 41% higher than that of the NaI(Tl) Scintillator, with…

This study demonstrates the application of response surface modeling within a Central Composite Design (CCD) to optimize the sorption processes of perfluorooctanesulfonic acid (PFOS) onto polyethylene microplastics (PE MPs), using simulation-based data from Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. The investigation intricately analyzes the complex interactions governing sorption phenomena (i.e. temperature and PFOS loading counts) with responses such as sorption energy, sorption density, and binding energy, employing RSM within a CCD framework. The…

It is well known that when two fluids with different specific densities are put adjacent to each other, there is an unbalanced horizontal density gradient that results in the adjustment process to achieve equilibrium, so that the less dense fluid finds its way atop the denser fluid. The purpose of this study is to employ light attenuation technique to obtain quantitative data in investigating the mentioned phenomenon. Specifically, the gravity current experiment models what is commonly found in estuaries, where there is an unbalanced density gradient due to the different densities of…

The Lembang Fault is one of the major faults in the province of West Java, approximately 10 km north of its capital, Bandung, a city inhabited by more than 2 million people. The fault exhibits distinct geometrical characteristics in its 29 km length, transitioning from normal, strike-slip, to vertical faulting mechanisms. Two studies have evidence of a normal fault with a dip direction to the north and a thrust fault with a dip direction to the south. Despite the lack of significant recorded earthquakes, the Lembang Fault is active and poses a high seismic hazard to the surrounding region.…

Alternative fuels play an important role in eco-friendly transport solutions. Wider adoption of alternative blended fuels in automobiles is dependent on a better understanding of the blended fuel engine characteristics. This paper presents an experimental investigation on the part load combustion characteristics of a multi cylinder spark ignition (SI) engine fueled by E0 and E10 ethanol blends. Full factorial Taguchi experimental design was employed to include multi-level engine speed (rpm) and load (throttle %) variations. High-speed data acquisition was used to record combustion parameters…

The search for new natural materials as reinforcement in concrete has increased as an economic and ecological alternative. The purpose of this work is to study the behavior of natural mango (mangifera indica) and palm fibers without treatment, incorporated into concrete to improve its mechanical properties. The physical properties of the coarse (gravel) and fine (sand) aggregates were analyzed, as well as the physical and mechanical characteristics of the fibers used in this research. Concrete mixtures were prepared incorporating 0.2% and 0.4% fiber content with respect to the weight of fine…

This study employed molecular dynamics simulations utilizing the ReaxFF force field to elucidate the mechanisms underlying methane decomposition and hydrogen generation on nickel clusters (Ni37, Ni55, and Ni80). The transformation of methane into valuable products, including carbon species and hydrogen molecules, is of considerable significance owing to the abundance of methane and its potential role as an atmospheric pollutant. The findings suggest that Ni37 clusters had the highest initial reactivity, although they deactivated swiftly; conversely, Ni55 and Ni80 exhibited more consistent…

Graphene, a two-dimensional carbon allotrope, has garnered significant interest due to its exceptional properties and diverse applications. This study investigates the optimization of graphene synthesis parameters using plasma-enhanced chemical vapor deposition (PECVD) to enhance film properties and broaden their application potentials. Using a comprehensive factorial design approach, factors including electric power (ranging from 60 to 100 W), the acetylene-to-hydrogen ratio (ranging from 30:70 to 50:50), and discharge time (ranging from 10 to 30 minutes) were systematically varied, and film…

This study looks into the influence of tacticity on the heat conduction through isotactic and syndiotactic polystyrene. The experimental work includes the collection of five different batches of polystyrene pellets with different tacticity. The molecular weight, isotacticity index and coefficient of thermal conductance were measured using gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) and thermal conductivity apparatus, respectively. The results have indicated that there are relationships between these parameters for certain conditions. The obtained data show that…