Graphene quantum dots (GQDs) derived from nanocellulose were prepared with and without sulfuric acid pre-treatment, and applied in dye-sensitized solar cells (DSSCs). Using nanocellulose, a renewable carbon precursor from wood pulp, supports the development of bio-based materials for bioenergy and solar-to-electric energy conversion. Although acid treatment enhanced −COOH functionalization, excessive oxidation introduced structural defects that increased charge recombination and reduced photovoltaic performance. Acid-free GQDs produced higher photocurrent density than acid-treated samples, indicating better structural preservation and charge transport. However, both systems underperformed relative to conventional N719-only cells due to limited visible-light absorption and energy-level misalignment. Overall, acid-free synthesis offers a more sustainable route to nanocellulose-derived GQDs for environmentally friendly bioenergy and solar cell applications.
This study investigates the spatial and temporal dynamics of dissolved organic carbon (DOC) and particulate organic carbon (POC) in the Terengganu River Estuary (TRE), Malaysia, under neap and spring tidal conditions. Surface water samples were collected during longitudinal surveys at 22 stations, including both freshwater and coastal sites, across diurnal cycles. These samples were analyzed to assess DOC and POC concentrations, to evaluate their conservative and non-conservative behavior, and to identify their potential sources. Results showed significantly higher DOC concentrations [(284 ± 103) µmol/L] and POC concentrations [(89 ± 38) µmol/L] during spring tides compared with neap tides [(218 ± 67) µmol/L] and [(53 ± 15) µmol/L], respectively, attributed to tidal turbulence resuspending organic-rich bottom sediments. Diurnal variations revealed DOC and POC followed tidal cycles at a freshwater station (Sta. S22), with peaks during flood phases. In contrast, a coastal station (Sta. S5) exhibited inverse trends due to seawater dilution and retention near a breakwater. Both DOC and POC displayed non-conservative behavior, dominated by net additions along the salinity gradient, indicating the estuary acts as a source. Percentage concentration of low molecular weight (LMW) [molecular weight cut-off (MWCO) < 10 kDa] DOC was more prevalent during spring tides (60
Cyanobacteria is an indicator for freshwater ecosystem health. This study aims to (a) simulate the spatial distribution of cyanobacteria dynamics; and (b) optimize machine learning (ML) models with explainable artificial intelligence for cyanobacteria prediction in tropical freshwater lake. The water quality parameters (e.g. cyanobacteria concentration (μg/L), chlorophyll concentration (μg/L), turbidity, and cell count) were analysed from eleven sampling stations in Tasik Kenyir. The cyanobacteria dynamics was modelled via GeoPhyton analysis. Linear Regression (LR), Artificial Neural Network (ANN), and Extreme Gradient Boosting (XGBoost), were optimized to assess predictive performance. Strong temporal variability observed major peak in August and October 2024. High predictive capabilities were obtained by LR (training R2 = 0.9435; testing R2 = 0.9902), ANN (training R2 = 0.9660; testing R2 = 0.9739), and XGBoost (training R2 = 1.000; testing R2 = 0.7468). Feature importance analysis using SHapley Additive exPlanations (SHAP) identified cell count and chlorophyll as the dominant predictors.
Housing is a set of houses that are established with different functions for the owner with equipped infrastructure that is equipped according to the owner wishes. In determining the location of housing in Pringsewu district, the criteria were needed in accordance with the consumer’s wish. This study will be explained on how to determine the location of housing in Pringsewu district using weighted product method. Because the weighted product method can help decision making in determining the location of housing, the calculation only resulted the greatest value that will be chosen as the best alternative.
This study focuses on a nonlinear viscoelastic wave equation involving logarithmic nonlinearity. It considers a nonlinear distributed delay influencing the boundary feedback, which is coupled with acoustic and fractional boundary conditions. Following the proof of global existence, we demonstrate the exponential growth and blow-up of solutions with positive initial energy under appropriate assumptions and for a general case of the kernel. This finding broadens and enhances earlier results.
