Research Articles

The appropriate use of forest biomass can support the transition to a society with clean and renewable energy. In this context, the research aimed to evaluate the waste biomass from Tectona grandis L.f. for energy purposes. Seven teak wood waste types were used, accessible from the harvesting stage to wood processing. Physical attributes (moisture and basic density) and proximate analysis (volatile materials, ashes, and fixed carbon content) were evaluated, which were used to estimate the energy attributes (higher, lower, and net heating value and energy density). It was found that most waste components had moisture content averages below 30% and did not differentiate statistically. For the basic density, values varied between 366 and 519 kg.m^-3. Proximate analysis and energetic attributes of the teak wastes support its feasibility for bioenergy use, focused on trimmings and thin logs. It was concluded that teak waste has the potential for energy purposes if its specific characteristics are considered and appropriate ways of use and conversion are chosen.

The influences of nano-chitosan and cationic polyacrylamide (cPAM) on the optical and mechanical properties of paper made from chemi-mechanical pulp (CMP) were investigated. Bleached chemi-mechanical pulp (CMP) was selected as the control sample. The cPAM was considered at four levels (0%, 0.25%, 0.5%, and 0.75%), while chitosan was added to the CMP suspension at three levels (0%, 1%, and 2%). Paper test specimens were prepared according to TAPPI standards with a basis weight of 60 g/m², and their optical and mechanical properties were measured. The results indicated that the opacity, greenness, tear strength, burst strength, and Gurley seconds were increased, whereas brightness, water absorption, and a* factor were decreased by increasing the amount of cPAM. Adding chitosan to CMP increased the a* factor, tear strength, breaking length, burst strength, Gurley seconds, water absorption, and greenness in the resulting paper. When polyacrylamide and nano-chitosan were added simultaneously to CMP, the brightness, water absorption, and greenness of the resulting paper decreased, but opacity, burst strength, tear strength, and air resistance had an appropriate increase. In all treatments, the best results were found at 1% chitosan and 0.5% cPAM due to favorable optical and mechanical properties.

To study the seismic performance of wood frame structures filled with light wood shear walls, three full-size single-layer single span wooden frame structures with infill walls were designed and manufactured. The beams and columns were connected by mortise-tenon joints, and quasi-static tests were conducted on the specimens under reversed cyclic load. The failure modes and load-displacement hysteresis performance of structures with door opening infill wall, window opening infill wall, and solid infill wall were investigated. The seismic performance was analyzed using indicators such as strength, ductility, and equivalent viscous damping ratio. The failure modes of light wood frame filling walls were the tearing of sheathing panel and the failure of nail connections. The filled wall with the opening initially exhibited inclined cracks at the corner of the opening, and then they extended to the periphery. Compared with the solid filled wall, the positive and negative bearing capacity of the structure with door opening decreased, and that of the structure with window opening decreased also. Because the specimens with opening in the filled wall were more conducive to the deformation of the structure when the bearing capacity was not significantly reduced, the ductility of the specimen with door opening was the highest.

Species belonging to the genus Citrus are produced and traded in large amounts around the world. In addition to the consumption of citrus fruits as food due to their high vitamin C content, their use in many areas has become widespread with the development of the plant-based products industry. In this study, the amount and structure of volatile components of leaves and flowers of 5 different citrus species (Citrus aurantium, Citrus limon, Citrus paradisi, Citrus reticulata, and Citrus sinensis) were determined using the solid phase micro extraction. Monoterpene hydrocarbons and their oxygenated derivatives were identified as the most abundant chemical component groups. Limonene was the dominant compound in Citrus limon flowers (36.5%), leaves (22.5%) and Citrus paradisi flowers (22.4%). Linalool, and sabinene were the other major components. Linalool was determined at 50.5% in flowers and 73.3% in leaves of Citrus aurantium. Moreover, sabinene had a high amount in Citrus sinensis flowers (19.7%), leaves (24.7%), and in Citrus paradisi (27.4%) leaves. Apart from these dominant components, γ-terpinene (13.9%) and p-cymene (25.4%) were detected in Citrus reticulata flowers and leaves in an important amount. It was seen that the leaves and flowers of Citrus species gathered from Hatay province were an important source of limonene and linalool compounds.

The catalytic conversion of biomass into high-value chemicals, such as furan derivatives, from 5-hydroxymethylfurfural (HMF) holds significant importance. In this study, a bifunctional catalyst prepared from phosphomolybdic acid (PMA) and chitosan was developed for the one-pot synthesis of 2,5-diformylfuran (DFF) from fructose. This approach offered the advantage of bypassing the solvent consumption and cost associated with HMF separation and purification for DFF production. The catalytic activity of the prepared catalyst primarily originated from the loaded PMA. Under optimized reaction conditions, the catalyst achieved a DFF yield of approximately 60% after a 6-h reaction at 150 °C or a 1-h reaction at 170 °C. Moreover, the catalyst exhibited good stability and reusability. These results highlight the potential of the bifunctional catalyst for efficient and cost-effective conversion of fructose into DFF, enabling practical applications in the production of valuable chemicals from bioresources.

Mechanical behavior properties were investigated for cabinet-type cabinet doors in kitchen furniture and drawer bottoms and joints used as storage areas under load in accordance with relevant standards (BS EN 16122). In the first stage, values physical and mechanical for particle board (PB) and medium-density fiberboard (MDF) were determined. According to the test results in the second stage, it was determined that the doors assembled using a torque of 1.3 N/m in the door tests were less deformed than those assembled with 0.63 N/m. According to the finite element analysis and real test results carried out in the final stage, it has been determined that the vertical loading analysis applied on the doors coincides with the real experiments by 85%, horizontal loading by 84%, and slam shut by 50%. The doors didn’t pass the final stage durability test in real experiments, and the analysis results revealed that the deformation areas were the same as for real experiment. In the drawers; strength 85%, displacement 84%, and slam shut 94% overlap are represented. The drawers completed the durability test in real experiments, and in the analysis, it was determined that the deformation that occurred under high stresses was in the same areas.

The limits of the pulp screening operation can be defined as the maximum throughput before the apertures start to plug permanently. This two-part article sought insights into the limits of screening operation. In part two, the operational window of the screen was characterized by performing a series of screening trials with different pulp furnishes, where the plugging point was conventionally measured with the pressure signal. The limits of operation, given by a slot velocity and rotor speed contour, showed a robust linear relationship at the point of plugging, which depended on the ratio of the fibre length to aperture size. For size ratios less than 1.5, the screen did not plug under the conditions tested. In addition, the plugging detection tool was conceptualized in part one based on the kurtosis of the distribution of fluctuation peaks, and it was employed here. Effectively, deviations from the Gaussian distribution of the pressure fluctuation peaks signal the onset of screen plugging. Thus, the utility of this tool was confirmed for detecting plugs using readily available pressure fluctuation data in pilot-scale screening operations.

Laboratory and field experiments were performed to examine the feasibility of using Time Domain Reflectometry (TDR) to monitor moisture content (MC) of wood and standing trees. The TDR was used to detect the electromagnetic wave propagation time of four tree species (Betula platyphylla, Tilia tuan, Picea asperata, and Fraxinus mandshurica) at different MCs. During the TDR test, effects of probe insertion depths on MC predictive accuracy were considered. The best results were obtained at an insertion depth of 8 cm. At the selective 8 cm insertion depth, a species-specific MC prediction model (0.94 ≤ R² ≤ 0.98), a generalized model for the four species (R² = 0.65), and a hybrid model for the species with similar densities (0.80 ≤ R² ≤ 0.96) were constructed, respectively. Overall, the species-specific MC prediction model showed good predictive ability for both tree and wood disc samples, including that TDR can be used to detect wood and standing tree MC. If possible, the hybrid model can be used for species with similar density.

Digital image correlation (DIC) was used to examine the strain distribution of heat-treated beech and Uludag fir woods in mechanical testing. It also evaluated the effects of the heat treatment process on the properties of the wood samples. The physical (mass/density loss, dimensional stability, color change, and surface roughness), mechanical (flexure test and compressive strength), morphological, thermal, and structural properties of the heat-treated wood were examined. It was determined that the heat treatment parameters can be optimized using the DIC method. The test results showed that although heat treatment can provide improved physical and thermal properties, it caused micro-crack formations and collapses in the wood cells. As a consequence, the mechanical properties of the heat-treated wood materials decreased with the heat treatment process. There were slight differences in the curves of the samples according to Fourier infrared and X-ray diffraction analyses. Morphological characterization showed that the heat treatment triggered large cracks in the cell wall and lumens and the morphological structure of heat-treated wood was affected at large percentages.

To establish the constitutive model of original bamboo, the tensile and compressive tests along the grain of original bamboo were investigated. The original bamboo was graded according to the elastic modulus, and a stress-strain constitutive model of original bamboo was proposed. The results of the study show that the tensile failure mode of original bamboo along the grain is brittle failure, and the compression along the grain is ductile failure. The bamboo was divided into three grades I, II, and III, and the proportion of II and II was more than 80%. A linear constitutive model was used for tension along the grain of original bamboo, a “three-fold” model was used for simplified constitutive model for compression along the grain, and the Sargin model was used for accurate constitutive model. The classification method proposed in this paper can result in the efficient utilization of bamboo resources, and the proposed constitutive model can promote the analysis and engineering application of original bamboo architecture.