Band 78, Heft 7

Scots pine knotwood contains valuable amount of stilbenoids such as pinosylvin (Ps) and pinosylvin monomethyl ether (PsMME). The stilbenoids have numerous biological activities. Traditional methods of extracting stilbenoids often yield low quantities and involve complex processes. In the present study, a simple and high-yield method was proposed for the extraction of stilbenoids from fresh Scots pine knotwood using ethanol taking a total of three days. In addition, the impact of drying process, extraction time, extraction solvents (acetone and ethanol) and storage time were evaluated on the yield of the stilbenoids. The increased yield and improved extraction efficiency make this method a promising advancement for promoting the utilization of stilbenoids for their valuable bioactive properties.

Using pyrolysis–gas chromatography–mass spectrometry, the lignin composition was analysed in normal and reaction wood samples grown at three stem inclination angles in Gardenia jasminoides , which forms compression wood-like reaction wood. Lignin content among the samples was not significantly different. However, the reaction wood samples with larger stem inclination angles showed a lower syringyl/guaiacyl ratio. In conclusion, the degree of inclination affected the lignin composition in G. jasminoides reaction wood, and qualitative changes in lignin might be necessary to mechanically support the stems in this species.

Beech wood, renowned for its diverse applications spanning construction, flooring, furniture, veneer, and plywood, holds a paramount position among industrial wood species. Nevertheless, the myriad of beech species worldwide, coupled with the dynamic impact of climate change, have produced structural variations within beech trees. Extensive research has scrutinized the physical and mechanical attributes of beech wood species across the globe. Findings reveal distinguishable mechanical strength, yet increased density leads to notable rates of shrinkage and swelling, somewhat constraining its utility in select domains. Identifying research gaps can create new efforts aimed at exploiting the potential of these wood resources. This paper outperforms a mere exploration of beech wood properties over the past two decades; it delves into the ramifications of climatic fluctuations, temperature shifts, wind dynamics, and soil composition. Given the lack of a comprehensive compendium documenting the full range of physical, mechanical, and microscopic attributes of the Fagus genus, this paper aims to compile information that integrates this multifaceted information.

The magnitudes of the color changes in heat-treated wood are closely related to the chemical composition of the wood, and changes in the chemical composition are the essential reasons for changes in the mechanical properties of heat-treated wood. The response relationships among the color parameters of heat-treated wood and the chemical composition were constructed to provide a scientific basis for regulating the mechanical properties with the color. The effects and linear correlations of the lightness indicators (L * ) for poplar ( Populus tomentosa Carr.) and spruce ( Picea asperata Mast.) after heat treatment were related to the chemical compositions of the heat-treated woods by constructing relationships between the L * values. The relative content of cellulose in the heat-treated poplar downward trend and was significantly positively correlated with the L * value; however, the correlation with the L * value for the heat-treated spruce was insignificant. The L * value of the heat-treated wood was significantly positively correlated with the relative contents of hemicellulose, and was significantly negatively correlated with lignin. The L * value of the heat-treated wood had a superior response relationship with the crystallite sizes. Therefore, the constructed response relationship provides a theoretical basis for accurate and nondestructive testing of the mechanical properties of heat-treated wood by using the color parameters as rapid detection indicators.

This study aimed to investigate the elastic deformation of rotational wood-dowel welding joints by using the variational method, as there was no efficient tool to access the deformation behavior of welding joints perpendicular to axis orientation so far. Based on the variational method, the displacement control equation of axially-loaded dowel-welded wood joints was derived. By incorporating the boundary conditions and using an iterative approach, the parameters required in the control equation were determined. The analytical expression ϕ ( r ) for the deformation function of the wood substrate under elastic conditions was proposed, thereby determining the displacement and axial force of the single wood-dowel. The elasticity modulus was the primary influence parameter on the function ϕ ( r ). However, the welding depth had a more critical impact, and reasonable combination of parameters could lead to a better interaction between the wood dowel and substrate. The comparison between calculated results and test trials collected from the previous studies indicated that the elastic solution method could accurately estimate the pull-out ultimate bearing capacity and deformation characteristics of the welding joints. This work can provide unique perspective to understand the technology of rotational wood-dowel welding joints, and a good reference suggestion for the manufacture of multi-dowel welding joints.

The increasing recognition of the need for economically viable carbon materials in supercapacitors has resulted in a notable emphasis on utilizing recycled biomass waste as a precursor for activated carbon (AC). This study investigates the production of highly porous AC through vertically aligned graphene nanosheet arrays (VAGNAs) derived from bamboo parenchyma cells, a type of biomass waste. The focus lies in manipulating the ratio of alkali to carbon during the activation process. Elevating the alkali-carbon ratio augments the specific surface area of the AC while concurrently reducing the presence of VAGNAs. Surprisingly, AC generated with an alkali-carbon ratio of four exhibits a remarkable specific capacitance of 215 F g −1 when subjected to a current density of 0.2 A g −1 . When integrated into a supercapacitor apparatus, this AC material demonstrates a notable energy density of 11.2 W-hours per kilogram (Wh kg −1 ) at a power density of 50 W per kilogram (W kg −1 ). Moreover, it displays exceptional cycling stability, maintaining 89.4 % of its capacitance after undergoing 10,000 cycles in a 6 M potassium hydroxide electrolyte. The findings of this investigation underscore the potential of utilizing waste bamboo parenchyma cells for sustainable energy storage applications.