Research Articles

Subterranean termites are major biological agents causing wood deterioration in tropical regions. Laboratory bioassays commonly use susceptible reference materials as controls to ensure termite feeding activity; however, information on the long-term variability of such materials remains limited. This study evaluated the variability and repeatability of Hevea brasiliensis (rubberwood) as a control material in laboratory tests involving Coptotermes curvignathus. Data from 27 independent trials conducted between 2016 and 2025 were analysed, with five replicates per trial exposed for four weeks using a standardized Forest Research Institute Malaysia in-house method. The mean density ranged from 0.584 to 0.701 g/cm³, while mean weight loss varied from 3.97% to 17.34%. The coefficients of variation for density, weight loss, and visual rating were 6.40%, 39.73%, and 13.11%, respectively. Weak correlations were observed between density and weight loss (r = 0.108), density and visual rating (r = −0.091), and weight loss and visual rating (r = −0.281). The results indicate that variability in feeding damage was primarily influenced by biological differences among termite colonies rather than wood density. Hevea brasiliensis was confirmed as a consistent and suitable control material for laboratory termite bioassays.

Poplar wood specimens were fabricated via surface swelling pretreatment with NaOH solution combined with a hot-pressing process. The three factors NaOH concentration, hot-pressing temperature, and hot-pressing time were considered relative to shear strength. The optimal process parameters for poplar adhesive-free bonding were surface swelling with 5% NaOH solution, a hot-pressing temperature of 140 ºC, and a hot-pressing time of 60 min. Under these parameters, the shear strength of the prepared specimens’ bonding interface reached 4.87 MPa. Analysis of variance showed that hot-pressing temperature exerted a highly significant effect on shear strength and that temperature was the dominant factor influencing adhesive-free bonding performance. Scanning electron microscopy observations indicated that NaOH solution surface swelling had a notable impact on the adhesive boundary, facilitating the formation of a dense adhesive layer in this area. Furthermore, a distinct phenomenon of molten lignin encapsulating fibers was observed at the bonding interface. As a natural bonding medium, molten lignin effectively enhances the bonding between fibers, thereby improving the adhesive-free bonding strength of poplar wood. Hemicellulose underwent substantial degradation, while no significant degradation was observed in the skeletal structure of lignin. This study provides a theoretical foundation and technical reference for optimizing the poplar wood adhesive-free bonding process.

Expanded polystyrene (EPS), widely used in plastic packaging, poses recycling challenges and contributes to environmental pollution due to its persistence. As an alternative, biopackaging materials were developed using mycelium from Ganoderma lucidum and agave bagasse (Agave tequilana Weber var. azul), a common agro-industrial residue in Jalisco, Mexico. The resulting materials showed a uniform, lightweight structure. SEM analysis confirmed full colonization of agave fibers by mycelium, indicating good cohesion. FTIR spectroscopy suggested intermolecular interactions between the fungal matrix and the lignocellulosic substrate. The material also exhibited hydrophobic behavior, as evidenced by its high water contact angle, indicating a surface with low wettability. In fire tests, the biopackaging burned slowly, emitted white smoke, and exhibited self-extinguishing behavior. Mechanical testing showed that the composites reached maximum force values in the same order of magnitude as EPS. Although flexural strength was slightly lower, the material tolerated greater deformation under comparable loads, indicating improved strain accommodation and resistance to abrupt fracture. Using the LIDS (Life Cycle Design Strategy Wheel), these materials were compared to conventional plastics, demonstrating advantages such as reduced reliance on petroleum-based polymers, valorization of agave waste, and alignment with circular production strategies in the tequila sector.

The techno-economic and environmental performance was assessed for the composting of oil palm empty fruit bunches (EFB) through an aerated bunker composting (ABC) system. The process flowsheet was developed using SuperPro Designer, with process data and operating parameters sourced from prior experimental and industrial studies. Simulation results exhibited agreement with literature data, demonstrating the reliability of the model. The process is potentially able to achieve a 79% reduction in carbon dioxide equivalent (CO₂e) emissions relative to landfilling, underscoring considerable climate mitigation potential. Economic evaluation estimated capital expenditure (CAPEX) at MYR 43.8 million and OPEX at MYR 15.7 million/year, with enriched compost contributing to 73.3% of revenues. The base case yielded a net present value (NPV) of MYR 58.4 million, return on investment (ROI) of 30.5%, and payback of 3.28 years, demonstrating strong feasibility. Scenario analysis revealed that increasing the portion of enriched compost substantially improves profitability, while carbon credit and CAPEX incentives further enhance investment appeal. Sensitivity results highlighted the enriched compost price, annual operating time, and CAPEX as the main determinants of financial performance. Overall, the system provides both substantial environmental benefits and compelling economic viability, offering a scalable pathway for sustainable EFB management.

Heat treatment of Paulownia tomentosa wood was studied relative to the physical and mechanical properties, with a view to expanding the potential fields of use of this species. Several physical properties (density, water absorption after 2 and 24 h, thickness swelling) and mechanical ones (strength and modulus of elasticity in static bending, tensile strength parallel to the gran and Brinell hardness) were evaluated. Most physical and mechanical properties of Paulownia wood were superior in the radial direction, with the exception of tensile strength, regardless of whether the samples were subjected to torrefaction treatment or not. In addition, the water affinity of heat-treated wood decreased significantly, with water absorption after 2 h of immersion reduced by 21% and tangential thickness swelling after 2 h of immersion reduced by 36.6%. The static flexural modulus of elasticity decreased by 12.1% at temperature of 160 ºC treatment, by 39.9% for the 180 ºC treatment and by 52.8% for the at temperature of 20 ºC treatment.

Accurate prediction of wood-drying rates is essential for enhancing drying efficiency and product quality; however, reliable models remain scarce, particularly for solar drying systems. In this study, poplar wood was dried in a solar kiln, and moisture content was determined through periodic mass measurements. The drying rate was calculated from the moisture content reduction over time, while kiln temperature and relative humidity were continuously monitored using calibrated sensors. Experimental results showed that poplar wood with an initial moisture content of 73.2% required approximately 130 h to reach a final moisture content of 7.5% under solar drying conditions. Based on an analysis of key physical factors affecting the drying process, kiln temperature, relative humidity, and wood moisture content were selected as input variables, with the drying rate as the output variable. Several optimization algorithms were evaluated, and a particle swarm optimization–support vector regression (PSO-SVR) model demonstrated the best performance. The optimized model achieved a mean squared error of 0.00105 and a mean absolute error of 0.039, indicating high prediction accuracy. In addition, the training time was reduced to 0.275 s, reflecting excellent computational efficiency. These results confirm that the PSO-optimized SVR model can be both accurate and efficient, i.e., practical industrial wood-drying applications.

Bamboo-fiber-reinforced polylactic acid (B-PLA) composites have emerged as promising materials for sustainable engineering applications due to their biodegradability, favorable mechanical properties, and renewability. This work systematically evaluated the thermal behavior and tribological performance of B-PLA composites using methods such as Vicat softening temperature measurement (VST), thermogravimetric analysis (TGA), and abrasive wear testing under varying loads, distances, and abrasive types. The results demonstrated that bamboo fiber reinforcement significantly increased the Vicat softening temperature compared with neat PLA, indicating enhanced thermal resistance. Thermogravimetric analysis revealed that the maximum degradation temperatures of the composites (303 to 317 °C) were comparable to neat PLA, confirming good thermal stability without phase separation. Tribological evaluation showed that specimens fabricated at a nozzle temperature of 245 °C exhibited approximately 37.5% lower wear mass loss than those fabricated at 195 °C, owing to improved interfacial bonding and higher surface hardness. Furthermore, Al₂O₃ abrasives produced the highest wear because of their greater hardness and density, while SEM observations confirmed reduced abrasive embedding and improved fiber-matrix adhesion in high-temperature processed composites. These findings demonstrate that optimized FDM processing significantly enhanced the thermal and wear performance of sustainable bamboo/PLA composites.

The kiruncong is a traditional bamboo idiophone of the Bidayuh community in Sarawak, Malaysia, whose acoustic characteristics have received limited scientific investigation. This study examined the frequency spectra, pitch characteristics, and rhythmic function of a single Kiruncong instrument set using Fast Fourier Transform (FFT) and time-frequency analysis (TFA). The six bamboo tubes produced fundamental frequencies of 199, 396, 391, 408, 463, and 507 Hz, corresponding approximately to G3, G4, G4, A♭4, B♭4, and B4. For Tubes 2 to 6, the measured fundamental frequencies were consistent with the perceived pitches. However, Tube 1 exhibited an anomalous pitch perception, with listeners identifying C4 despite a measured fundamental of G3. Since the measured partials did not form the harmonic series required for the classical missing fundamental phenomenon, the perceived pitch is likely influenced by psychoacoustic factors such as inharmonic partials, resonance, transient characteristics, and spectral properties. The results show that the Kiruncong produces complex inharmonic spectra in which the fundamental frequency, partials, dominant spectral peaks, and perceived pitch are distinct acoustic attributes. Rhythmic analysis also revealed interlocking performance patterns characteristic of Southeast Asian traditional music. These findings provide baseline acoustic data that support future ethnomusicological research and the preservation of Bidayuh musical heritage.

Wood pellets represent one of the most important solid biofuels produced from renewable lignocellulosic biomass, yet the thermal behaviour of pellets containing alternative additives such as digestate from biogas plants remains insufficiently characterised. This study provides a dataset from simultaneous differential scanning calorimetry and thermogravimetric analysis for four wood pellet samples: three commercial Norway spruce pellets of different geographical origin and quality classes, and one experimental sample prepared as a one-to-one mass mixture of spruce sawdust and solid digestate from an agricultural biogas plant. Measurements were performed in an oxidative atmosphere from 30 to 700 degrees Celsius at a heating rate of 20 degrees Celsius per minute. The three commercial pellets exhibited consistent thermal behaviour, with decomposition onset temperatures falling within narrow ranges. The experimental sample showed substantially different behaviour, including a downward shift in the decomposition onset temperatures of hemicellulose and cellulose by 23 and 41 degrees Celsius, respectively, an elevated endothermic peak temperature consistent with stronger moisture binding, and a residual mass of 10 percent, which was six to ten times higher than that of the commercial pellets. These findings document that incorporating digestate fundamentally alters the thermal behaviour of wood pellets.

Microfibrillated cellulose (MFC) is a sustainable, bio-based material with remarkable mechanical properties and a large specific surface area. However, its inherent hydrophilicity limits its application in hydrophobic composite systems. In this study, hydrophobized MFC powders were prepared by treating MFC suspensions with alkyl ketene dimer (AKD) and then spray-drying. The MFC suspensions were treated with varying AKD dosages (1 to 3%, based on oven-dried MFC) and spray-dried at different inlet temperatures to determine the best hydrophobization conditions. Contact angle measurements indicated that hydrophobicity increased with rising AKD dosage, and the maximum contact angle was obtained at an inlet temperature of 120 °C. Fourier transform infrared analysis supported the retention of AKD-derived hydrophobic alkyl groups in the spray-dried MFC powders. Field-emission scanning electron microscopy images further revealed morphological changes from fibrillated structures to compact particulate morphologies after AKD treatment and spray drying. Notably, high hydrophobicity was achieved without an additional curing process, indicating that spray drying provided sufficient thermal energy for AKD-mediated hydrophobization. These results demonstrate that spray drying combined with AKD treatment can effectively produce hydrophobic MFC powders potentially suitable for composite applications.