Volume 21 Issue 4

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.

Bamboo has gained increasing recognition as a sustainable structural material; however, the development of reliable connection systems remains a critical challenge for its broader application in construction. This study investigated a tensile connection for bamboo culms based on the principles of internal expansion and lateral friction while addressing the material’s inherent dimensional heterogeneity. The system was designed to facilitate installation, reduce costs, and require only minimal skilled labor, thereby improving the technical and practical feasibility of bamboo construction. An experimental program was conducted to evaluate the structural performance of the connection under tensile loading. The results demonstrated consistent mechanical behavior and significant load-bearing capacity, confirming the effectiveness of the internal expansion mechanism in accommodating geometric variability along the culm. Three main groups were tested, differing in the additives incorporated into the wood expander: sandpaper and polyurethane resin. The configuration incorporating polyurethane resin achieved the highest average ultimate tensile load (4.47 kN). The findings indicate that the proposed connection has strong structural potential and may contribute to the development of more reliable, scalable, and sustainable bamboo construction systems.

Although much is known about the properties of fiberboard and its constituents as a composite material, their dependency on morphological properties of the fibers within remains relatively unstudied. Regardless of the exact defibration method used on wood, a certain range of fiber aspect ratios are produced. The influence of aspect ratio distribution on fiberboard performance has been studied in conjunction with its dependence on hardwood/softwood content. Fiber samples with a range of hardwood content were imaged using a digital microscope and measured using image analysis. Thin fiberboard made from the sampled wood fiber was subjected to a variety of performance tests. Testing of fiberboard was done according to ASTM Standard D1037-12 (2020). No significant difference in flexural performance was found between the samples, with strain at break being the only exception. It is concluded that while longer, softwood fibers may have more favorable properties in standard applications of fiberboard, shorter, hardwood fibers have comparable mechanical properties when made into thin fiberboard while exhibiting significantly higher performance in internal bonding and water resistance.

An amphoteric modification strategy was proposed to enhance the adsorption performance of biomass-based magnetic aerogels. Using sugarcane bagasse as the precursor, bagasse cellulose (BC) was extracted using a deep eutectic solvent at ambient temperature. Magnetic aerogels were fabricated by sequential cationization with 3-chloro-2-hydroxypropyltrimethylammonium chloride and anionization with 2-acrylamido-2-methylpropanesulfonic acid and amphiprotic BC/TiO₂ (AP-BC/TiO₂). These aerogels combined TiO₂ (a photocatalytic component) and Fe₃O₄ (a magnetic component) through an energy-efficient atmospheric pressure foaming process. The adsorption capacity for methylene blue (MB) was optimized using response surface methodology, with the mass concentrations of Fe₃O₄, AP-BC, and TiO₂ and initial concentration of MB as independent variables and the MB adsorption capacity as the response. A quadratic regression model was used to determine the optimal conditions. The AP-BC/TiO₂ magnetic aerogels exhibited an exceptional MB adsorption capacity of 1070 mg⋅g⁻¹. Adsorption kinetics and isotherms were modeled, and the structural/ physicochemical properties of the magnetic aerogels were characterized. The results confirmed the formation of a three-dimensional interconnected porous structure with uniform Fe₃O₄/TiO₂ loading and a saturation magnetization of 17.2 emu⋅g⁻¹. This enabled rapid magnetic separation and confirmed the potential application of amphiprotic biomass-based magnetic aerogels as eco-friendly and cost-effective adsorbents for MB.

The unique imidazole group of histidine endows materials containing it with pH responsiveness, metal-coordination capability, and π–π stacking interactions. However, the development of fully bio-based nanostructured supports that enable efficient histidine immobilization while maintaining abundant accessible surface functional groups remains largely unexplored. In this study, regenerated cellulose nanospheres (RCNs) with an average particle size of 88.8 ± 2.1 nm were prepared through a dissolution–regeneration process and subsequently oxidized to introduce reactive aldehyde groups. Histidine was then covalently grafted onto the RCN surface via a Schiff base reaction, yielding fully bio-based histidine/regenerated cellulose composite nanospheres (His-RCNs) with an average particle size of 39.3 ± 1.1 nm. The reduced particle size after grafting is expected to provide greater accessible surface area for interfacial interactions and subsequent functionalization. Morphological, structural, and thermal analyses confirmed the successful grafting of histidine while preserving the regenerated cellulose framework and spherical morphology. Quantitative analysis revealed that regenerated cellulose and grafted histidine accounted for 79.2 wt% and 20.8 wt% of the final product, respectively. By integrating the renewable regenerated cellulose nanosphere platform with multifunctional imidazole groups, this work provides a fully bio-based strategy for constructing histidine-functionalized cellulose nanomaterials.

Advances in microtechnology have progressively improved cultivation methods, providing significant benefit through hydrogel immobilization, which enables more controlled nutrient delivery and a conducive environment.  In this work, Chlorella vulgaris, a microalgal species, was used to investigate the cell cultivation and optimal growth conditions within cellulose-based bioinks composed of cellulose nanofibrils (CNF) and carboxymethyl cellulose (CMC). C. vulgaris immobilization serves as a bioprinted living cell model focused on a plant-based system, enhancing the understanding of a modern and simplified cultivation techniques. The growth rates of C. vulgaris cells in CNF/CMC hydrogels were evaluated using colorimetric analysis with different cell cultivation techniques. The morphological structure was analyzed within the CNF/CMC hydrogel, C. vulgaris culture, and the immobilized C. vulgaris in the hydrogel. The optimal conditions at room temperature for C. vulgaris growth were established by preparing the hydrogels with varying CNF and CMC concentration ratios for subsequent 3D bioprinting processes. Remarkably, the 3D-bioprinted hydrogel with a concentration ratio of 5 wt% CNF and 5 wt% CMC demonstrated superior structural integrity, with capability for 3D printing and exceptional C. vulgaris cell growth rates. A green and comprehensive method of nanocellulose-based bioinks showed great properties for the application of other cells’ culture with 3D bioprinting.