Volume 77, Issue 11-12

Microscopic lab-based X-ray computed tomography (XµCT) aided finite element (FE) modelling is a popular method with increasing nature within material science to predict local material properties of heterogeneous materials, e.g. elastic, hygroexpansion and diffusion. This method is relatively new to wood and lacks a clear methodology. Research intended to optimise the XµCT aided FE process often focuses on specific aspects within this process such as the XµCT scanning, segmentation or meshing, but not the entirety of the process. The compatibility and data transfer between aspects have not been investigated to the same extent, which creates errors that propagate and negatively impact the end results. In the current study, a methodology for the XµCT aided FE process of wood is suggested and its bottlenecks are identified based on a thorough literature review. Although the complexity of wood as a material makes it difficult to automate the XµCT aided FE process, the proposed methodology can assist in a more considered design and execution of this process. The main challenges that were identified include an automatic procedure to reconstruct the fibre orientation and to perform segmentation and meshing. A combined deep-learning segmentation method with geometry-based meshing can be suggested.

Accurate and rapid wood species identification is vital for wood utilization and trade. This goal is achievable with the fast development of deep learning (DL). Several studies have been published related to this topic; however, they were limited by their generalization performance in practical applications. Therefore, this study proposed a DL multimodal fusion framework to bridge this gap. The study utilized a state-of-the-art convolutional neural network (CNN) to simultaneously extract both short-wavelength near-infrared (NIR) spectra and RGB image feature, fully leveraging the advantages of both data types. Using portable devices for collecting spectra and image data enhances the feasibility of onsite rapid identification. In particular, a two-branch CNN framework was developed to extract spectra and image features. For NIR spectra feature extraction, 1 dimensional NIR (1D NIR) spectra were innovatively encoded as 2 dimensional (2D) images using the Gramian angular difference field (GADF) method. This representation enhances better data alignment with CNN operations, facilitating more robust discriminative feature extraction. Moreover, wood’s spectral and image features were fused at the full connection layer for species identification. In the experimental phase conducted on 16 difficult-to-distinguish wood samples from the Lauraceae family, all achieved identification metrics results exceed 99 %. The findings illustrate that the proposed multimodal fusion framework effectively extracts and fully integrates the wood’s features, thereby, improving wood species identification.

The article offers a perspective on how thermal-modification affects the impact bending strength of five different wood species, an aspect that has not received as much attention as the well-studied static load behavior of thermally-modified timber (TMT). Since the TMTs are mainly employed as outdoor materials, where they may encounter impact forces, a comparative investigation into the flexibility and strength of these materials under impact is useful. This article evaluates different aspects of the TMT, such as deflection, strain in the impact region, the maximum force needed to initiate cracks, and the energy required for rupture. Wood planks from ash, beech, larch, oak, and spruce were thermally modified at 180 and 220 °C. They were cut into test specimens, while a separate set of unmodified specimens from each wood species served as the reference group. The specimens were subjected to an impact 3-point bending test, and an ultra-high-speed camera meticulously recorded the results. The images were processed by the digital image correlation (DIC) method to determine the deflection and strain distribution of the beams during the impact test. The deflection, maximum force, maximum longitudinal strain, and required work for rupture of each group were determined. The results showed that thermal-modification decreases the wood deflection and maximum longitudinal strain by approximately 50 %. In addition, the impact bending strength decreased by nearly 60 %. However, the impact bending strength did not exhibit a statistically significant decrease at 180 °C; in some cases, it even increased.

With the growing risk of fungal degradation in timber-framed structures from significant moisture intrusion events due to climate change, it is increasingly critical to develop mechanistic relationships between fungal degradation mechanisms and the strength of untreated wood components. While extensive work has been performed characterizing wood decay, no study has yet addressed the effects of Meruliporia incrassata on untreated Southern Yellow Pine. This seeks to address this knowledge gap by evaluating the effects of the common brown rot fungus on an ubiquitous building material in the southeast United States – Southern Yellow Pine. Properties of Southern Yellow Pine were evaluated at seven decay stages over the course of 12 weeks of exposure to M. incrassata . Changes in physical properties – mass, density, and moisture content – were measured at each stage. Changes in stiffness were characterized via ultrasonic pulse velocity testing, and thermogravimetric analysis was utilized to assess compositional changes. The study found rapid and significant losses in stiffness at decay stages as early as four-weeks. Hemicellulose and cellulose degradation occurred steadily throughout the decay period. These results can be utilized to develop a stronger understanding of the mechanical behavior of timber-framed structures in the United States degraded by brown rot.

Understanding the durability of emerging plantation hardwood resources is important for optimising their production and use. This study compared timber density, extractives content and decay resistance in 12–13-year-old plantation and native forest regrowth Gympie messmate ( Eucalyptus cloeziana ) trees. Density increased from pith to bark for both plantation and native forest trees. Inner heartwood density of the plantation timber was significantly lower than that of the native forest regrowth timber. While the total extractives content of the outer heartwood was comparable in the plantation and native forest regrowth trees, the inner heartwood of the latter contained significantly greater extractives levels. Laboratory decay tests showed that all heartwood zones of plantation and native forest regrowth Gympie messmate were resistant to decay by the white rot Pycnoporus coccineus . The inner heartwood of the plantation timber was, however, susceptible to decay by the brown rot Fomitopsis ostreiformis . The results illustrate the potential variations in wood quality parameters to be considered when moving from native forest to plantation resources that are harvested at a younger age and managed for more rapid wood production.

This study involved analysing the carbon-13 isotope ratio (δ 13 C) of cellulose, lignin, and whole wood powder of Balanites aegyptiaca to determine the optimal substrate for future ecophysiological studies. From seven different trees (i.e., three from the Sudanian zone and four from the Chadian Sahelian zone), 21 samples were taken for this study. Identical variation trends were observed with cellulose, lignin, and whole wood powder, with δ 13 C values for cellulose always higher than for the other substrates, although the trees were located under different climatic conditions. The means obtained were −26.0 ‰, −28.7 ‰, and −27.1 ‰, for cellulose, lignin, and whole wood powder, respectively. Spearman’s correlation test, which was used to analyse relationships between the results, revealed a strong correlation ( r 2  = 0.93) between the δ 13 C cellulose values and those of whole wood powder from B . aegyptiaca , as well as between the δ 13 C cellulose values and those of lignin ( r 2  = 0.73). This strong correlation between cellulose and wood powder results, and between cellulose and lignin, suggests that the isolation of cellulose is not necessary for δ 13 C analysis of B . aegyptiaca wood.

The European Deforestation Regulation 2023/1115 (EUDR) prohibits trading of wood and wood products obtained from illegal logging on the EU market. While the identification of solid wood via anatomy, chemistry and genetics has already been established, there is a lack of identification methods for pulp and paper that complement anatomy. This publication presents a newly developed chemotaxonomic method for identifying mixed tropical hardwood (MTH) species in pulp and paper products based on their extractives analyzed with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). The measured data was processed and compared to identify marker substances and was then merged into a fingerprint database for identifying MTH species in paper of unknown composition. As database references, fully bleached kraft pulps were produced from 38 anatomically identified wood samples and then cryo-ball milled and extracted successively with n -hexane and acetone. The results show that the remaining wood extractives generated from bleached pulps are specific enough to find chemical relevant marker substances to detect MTH species. As chemical composition and anatomy are independent characteristics of wood, this paper makes a completely independent method available, which potentially improves the screening for Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) protected species.

This study was conducted to investigate the uptake of castor oil (CAO) in some wood specimens and the effect of CAO on the leaching ability, dimensional stability and fungal-decay resistance of the wood specimens. CAO was infused into the specimens using a pressure treatment. Uptakes of CAO penetrated in yellow poplar (YEP), Japanese cedar (JAC) and Douglas fir (DOF) blocks were higher than 100 %. The leaching ability of the CAO-based suspensions against saline water was the lowest in YEP, followed by Japanese larch (LAR), JAC and DOF. The retention values were 90 % or higher in most of the specimens. Radial and tangential swellings of CAO-treated strips submerged in saline water for 2 weeks were restrained compared to control specimens. No significant differences were found between bending strength and Janka hardness of CAO-treated and control strips. CAO treatment provided acceptable decay resistance to most wood specimens against Fomitopsis palustris and Trametes versicolor . Retention of CAO in the leached strips were identified through X-ray microscopic observation. Based on the results, CAO was determined to be an effective agent for improving the dimensional stability of wood. These results demonstrate the great potential of CAO as an environmentally friendly wood preservative and dimensional stabilizer, allowing CAO-permeated wood as raw materials for both indoor and outdoor use.

This study investigated the characteristics of radial cracks in Castanopsis hystrix wood and evaluated its dimensional stability after impregnation with low-molecular-weight polyacrylate (PA), melamine-urea-glyoxal (MUG), and melamine-urea-formaldehyde (MUF) resins. The physical properties were examined by dimensional stability measurements, dynamic vapor sorption (DVS) analysis, and scanning electron microscopy (SEM). The results showed that radial cracks were easily produced in the transverse section of untreated wood during drying. The surfaces of the radial cracks exhibited an even and clean structure without fluffs on the pair of surfaces, and cracks spanned 4–5 annual rings. The resin-impregnated wood showed no radial cracks on its transverse surface. C. hystrix wood modified with MUG and MUF exhibited a higher weight percentage gain (WPG) than wood modified with the same concentration of PA resin. The resin-impregnated C. hystrix wood also showed reduced anisotropy and improved dimensional stability. The SEM images of the modified wood showed that the wood pits and cells were filled with resin, while the cell wall surfaces were covered with a layer of resin.