Research Articles

Effects of a boron-phenol-based flame retardant were evaluated relative to the combustion performance and mechanical properties of structural plywood manufactured from two domestic softwood species: larch (Larix kaempferi) and Korean pine (Pinus densiflora). The flame retardant was applied using a standardized vacuum-pressure impregnation process, and the retention level, combustion resistance, and structural integrity of the treated specimens were determined. The results showed that the treated specimens met the Korean standard (KS F 3113) requirements for bending strength, modulus of elasticity, and water-resistant tensile-shear strength. Larch plywood exhibited modest changes in combustion and mechanical performance, whereas Korean pine showed significant improvements in flame retardancy, including longer ignition time, lower peak heat release rate, and reduced char length and area owing to the higher flame-retardant retention achieved with Korean pine. Furthermore, flame retardant impregnation did not affect adhesive bonding in either species. This study demonstrates that boron–phenol-based flame retardants can effectively enhance fire resistance in structural plywood without compromising its mechanical performance, thus supporting their applicability in manufacturing flame-retardant wood-based construction materials.

As more people use chemical preservatives and antibiotics, there is a growing need for safe, natural alternatives. It was posited that black seed oil (Nigella sativa) (BSO) and its nanoemulsion (BSO-NE) might exhibit significant antibacterial efficacy against clinically pertinent pathogens. To verify this, BSO-NE was synthesized utilizing the emulsion inversion point (EIP) technique, yielding stable nanoscale oil-in-water droplets, which were validated by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). The antimicrobial activities of BSO and BSO-NE were tested against a group of Gram-positive and Gram-negative bacteria using CFU-reduction assays and agar well diffusion. BSO strongly inhibited the growth of Staphylococcus epidermidis (96.6% CFU reduction), while BSO-NE showed varying but still significant activity against the strains that were tested. To investigate the mechanism, molecular docking of thymoquinone and thymohydroquinone with ATPase demonstrated greater binding affinities compared to the reference ligand, corroborating the experimental results. These results show that BSO could be a natural antimicrobial agent and that improving NE formulations could make them work even better. The research highlights the potential of essential-oil-based nanostructures as scalable options for pharmaceutical, biomedical, and food preservation applications.

Fly ash can enhance soil structure, nutrient availability, and water retention, making it a promising soil conditioner for agricultural applications. The growth and yield performance of Napier grass (Pennisetum purpureum) cultivar Pak Chong 1 was evaluated under different soil treatments. The control treatment consisted of 313 kg/ha NPK (Nitrogen, Phosphorus, and Potassium), 1,563 kg/ha dolomite, and 6,250 kg/ha manure, while fly ash was applied at levels of 1,563, 3,125, 6,250, and 12,500 kg/ha. Growth parameters such as plant height, number of tillers per clump, leaf-to-stem ratio, dry-to-fresh weight ratio, and heavy metal accumulation were examined. The fly ash significantly increased plant height, tiller number, and biomass yield compared to the control in most cutting cycles. However, the control occasionally exhibited higher leaf-to-stem ratios, suggesting that fly ash promotes stem growth more than leaf expansion, indicating an advantage for biomass production. Notably, the 3,125 kg/ha fly ash treatment resulted in considerable lead accumulation in leaves; however, this Pb originated from the native soil, not the fly ash, which had non-detectable levels. Higher fly ash levels (e.g., 12,500 kg/ha) effectively reduced Pb uptake, indicating the need for dosage optimization to ensure heavy metal immobilization.

This study aimed to investigate the effects of an expanded polystyrene (EPS) layer and varying precast concrete thickness on the stiffness and acoustic performance of cross-laminated timber (CLT) slabs. Six different concrete thicknesses and EPS layers were applied to larch and pine CLT slabs for testing. Airborne sound transmission loss (D_w) was measured using speakers, light impact sound (L_nT,w) using a tapping machine, and heavy impact sound (L_iA,Fmax) using rubber balls, in accordance with KS F ISO717-2. The results indicated that the EPS layer significantly improved light impact sound insulation (by 8 dB) and airborne noise insulation (by 5 dB), but had a minimal effect on heavy impact sound (0.5 dB). Both stiffness and sound insulation increased with concrete thickness, although improvement plateaued beyond 100 mm for larch CLT and 150 mm for pine CLT. The flexural and impact stiffness of larch CLT slabs were 24.3% and 19.2% higher than those of pine CLT slabs, respectively. Moreover, impact stiffness demonstrated a stronger correlation with acoustic performance than the previously established relationship with area density.