Tasik Aman (TA) and Tasik Harapan (TH) are critical water bodies located within the campus of Universiti Sains Malaysia (USM) that serve both ecological and flood management functions. They provide aquatic habitats for diverse species, support biodiversity and contribute to campus recreation and environmental aesthetics. However, these lakes are increasingly impacted by nutrient accumulation, primarily from the Sungai Gambir inflow, leading to algal proliferation and potential eutrophication. This study assessed the current water quality of TA and TH through physiochemical and biochemical parameters, including pH, temperature, electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS), dissolved oxygen (DO), biological oxygen demand (BOD), nitrite-nitrogen (NO2-N), ammonium nitrogen (NH4-N), chlorophyll-a, orthophosphate and water transparency. Most parameters were within the Malaysian National Water Quality Standard (NWQS), except for TSS, DO and BOD, which fell under Class IIB. Significant spatial variations in temperature, EC, BOD, NH4-N and chlorophyll-a (p < 0.05). These findings highlight the ecological significance of these lakes and underscore the need for sustainable management strategies to maintain water quality, protect aquatic ecosystems and enhance the utility of campus water resources.
This study investigates electrical and optical losses in silicon heterojunction (SHJ) solar cells. It evaluates single-layer anti-reflective coatings (ARCs), including silicon dioxide (SiO₂), magnesium fluoride (MgF₂), magnesium oxide (MgO), titanium nitride (TiN) and aluminium oxide (Al₂O₃) to enhance light absorption and carrier generation. A one-dimensional PC1D simulation is used to model the device’s electrical and optical behaviour and to predict key parameters, including short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (FF) and power conversion efficiency (PCE). It is also used to evaluate external quantum efficiency (EQE) and reflectance while optimising ARC layer properties. Results reveal that MgO delivers the best performance, achieving a peak VOC of 656 mV, JSC of 15.39 mA/cm², EQE of 93.1% at 630 nm and a minimum reflectance of 6.80%. Al₂O₃ and TiN follow closely, with EQE values of 92.98% and 92.83%, respectively, and reflectance minima of 6.91% and 7.05%, respectively. Meanwhile, SiO₂ and MgF₂ exhibit lower efficiencies, with peak EQE values of 83.73% and 86.27%, respectively. Overall, MgO, Al₂O₃, and TiN emerge as the most effective ARCs for improving Si solar cell performance.
The objective of this study is to numerically and theoretically model the coupled heat and mass transfer in a porous, isotropic and saturated medium filled with a Casson nanofluid containing aluminium nanoparticles, taking into account the effects of radiation, chemical reactions, a magnetic field and the Soret and Dufour effects. The analysis is conducted for various parameters relevant to the model, including the chemical reaction parameter (ranging from 0–20), the radiation parameter (0–2), the Casson fluid parameter (0.1–1), the Soret and Dufour numbers (0–1), the conductivity ratio (1–3), the Hartmann number (0–100) and the thrust ratio (1–2). The horizontal boundaries of the cavity are maintained at constant temperature and concentration, while the vertical walls are assumed to be rigid, impermeable and adiabatic. The flow of the Casson nanofluid in the porous medium is governed by the extended Brinkman–Forchheimer–Darcy law. The system of equations is solved using the finite volume method. The findings reveal that the heat transfer rate increases with the chemical reaction parameter, geometric aspect ratio, Casson fluid parameter, thermal conductivity and thrust ratio. Conversely, the heat transfer rate decreases with higher Hartmann and Dufour numbers. Regarding mass transfer, it increases with higher thermal conductivity, thrust ratio and geometric aspect ratio, but decreases with higher Hartmann number, Soret effect and chemical reaction parameter.
This study presents a comprehensive theoretical investigation into how iron (III) oxide (Fe₂O₃) doping alters the structural, electronic, optical, magnetic and thermodynamic properties of graphene. A finite-size C52 graphene cluster was used to simulate localised doping effects using Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT). The introduction of Fe₂O₃ significantly reduced the bandgap to ~1.6 eV and introduced mid-gap states, indicating enhanced semiconducting behaviour and reactivity, as confirmed by highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO–LUMO) gap and density of states (DOS) analyses. Optical simulations revealed increased absorbance in the visible spectrum, with characteristic peaks at 310 nm and 395 nm linked to Fe-graphene hybrid orbitals. Magnetic property analysis revealed increased anisotropy and shielding near Fe and O atoms, indicating the formation of localised magnetic moments. Structurally, Fe–C and Fe–O bonds formed stably, with minimal lattice distortion. Vibrational and thermodynamic analyses confirmed increased thermal stability and lower formation enthalpy. The novelty of this work lies in employing a finite-cluster DFT/TD-DFT model that captures localised Fe–O–C interactions and anisotropic magnetic behaviour, which are often overlooked in periodic systems. This integrated approach simultaneously explains the structural, electronic, and optical coupling mechanisms in Fe₂O₃-doped graphene, providing molecular-level insights consistent with experimental observations but previously unquantified theoretically. These findings highlight the potential of Fe₂O₃-doped graphene in optoelectronic devices, photocatalysis, spintronics and energy-related applications.
Organic liquid scintillators, such as EJ-301 scintillation detector, are widely used for neutron detection owing to their excellent pulse shape discrimination (PSD) capabilities. In this work, an EJ-301 scintillation detector was characterised at the neutron source facility, the Fast Neutron Laboratory (FNL) of Tohoku University, Japan, using incident neutron energies between 2.34 MeV and 5.54 MeV. The novelty of this study lies in the systematic evaluation of neutron energies using transport of ions in matter (TRIM) simulations, which account for energy losses in the Havar foil and deuterium (D2) gas target. The measured pulse-height spectra were further validated against Monte Carlo N-Particle (MCNP) calculations that incorporated the light output function and detector resolution effects. By varying the fast component integration time, an optimal value of 26 ns was determined, yielding stable neutron–gamma ray separation with figure-of-merit values up to 1.4 at 2.5 MeVee. The results provide benchmark data on EJ-301 scintillation detector performance and practical guidance for detector characterisation, supporting applications in D–D neutron spectroscopy on the Large Helical Device (LHD), in future fusion devices for fast-ion studies and in broader areas requiring reliable neutron measurements.
