Volume 79, Issue 1

Pterocarpus santalinus L.f. ( P. santalinus ), protected under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), is a high-priced, slow-growing, and scarce wood primarily used in crafting high-end furniture. The international timber trade currently faces issues of counterfeit P. santalinus , with commonly used substitutes including Dalbergia louvelii R.Viguier, Pterocarpus tinctorius Welw., Gluta renghas L. and Baphia nitida Lodd. This study aims to develop a P. santalinus authenticity identification model based on near-infrared spectroscopy (NIRS) technology. The NIR spectral pretreatment involved the use of four methods, either individually or in combination: multiplicative scatter correction (MSC), moving average smoothing (MAS), Savitzky-Golay (S-G), autoscaling (AUTO) and standard normal variate (SNV). An authenticity identification model for P. santalinus based on long short-term memory (LSTM) was established and compared with commonly used support vector machines (SVM) and random forest (RF) models. The results indicate that the accuracy of the MSC-LSTM model is 97.1 %, with precision, recall, and F1 score all exceeding 0.85. In identifying P. santalinus in the test set, the MSC-LSTM model has an error rate of only 4.8 %. LSTM performs outstandingly across multiple indicators, demonstrating its ability to identify P. santalinus authenticity. The developed MSC-LSTM P. santalinus authenticity identification model shows enhanced accuracy compared to SVM and RF, significantly reducing misidentification of P. santalinus .

This study explores the application of chemotaxonomic methods to trace the geographic origin of wood used in paper production. Utilizing thermal desorption gas chromatography-mass spectrometry (TD-GC-MS) and principal component analysis (PCA), distinct chemical profiles were identified in both hydrophobic and hydrophilic extracts. Residual wood extractives, that are capable of origin differentiation, were found in acetone extracts of the CITES-protected genus ramin ( Gonystylus Teijsm. et Binn. spp.), petroleum ether extracts of red meranti ( Rubroshorea (Meijer) P.S.Ashton et J.Heck. spp.) and n-hexane extracts of teak ( Tectona grandis L.f.) pulp. The PCA results demonstrate the potential of these chemical fingerprints to serve as reliable indicators of wood provenance, which could potentially be crucial for the practical execution of the European Deforestation Regulation (EUDR) and the US Lacey Act in the paper industry. Despite the promising findings for ramin and teak, the effectiveness of the method to distinguish the origin of red meranti pulps was limited in some cases.

Functional traits like hydraulic conductivity and vulnerability to cavitation are increasingly important due to climate change. In conifers, water is transported through lumina of tracheids connected via bordered pits, which severely limit xylem conductivity by causing large pressure drops related to their number, dimensions and structure. According to literature, numbers and dimensions of pits correlate positively with tracheid and lumen dimensions. This reflects variations from earlywood to latewood and between rings formed under different grow conditions, contributing to major conductivity variations. The wider aim of the work is to estimate such conductivity variations in trunkwood from measurement data on radial and axial variations of tracheid dimensions. This requires several integrated models, including models estimating numbers and dimensions of pits. The article presents such models developed on data from 27 Norway spruce trees representing different sites, clones and growth rates. Measured and estimated variations of tracheid, lumen and pit properties within and between rings are illustrated, indicating on average about one third smaller and fewer pits in latewood than in earlywood tracheids, and variations in numbers and areas of pits per unit volume of xylem which may be interesting also in fields like wood drying and impregnation.

Hydraulic conductivity of conifer sapwood varies greatly between and within annual rings due to varying dimensions and numbers of tracheids, lumina and bordered pits, complex relationships and non-linearities. Existing laboratory methods are too tedious and expensive for large scale studies for instance of genetics, tree improvement and silvicultural practices, and their spatial resolution is not enough for information on seasonal weather effects which may reflect vulnerability to drought. The article presents a set of integrated models estimating radial variations in hydraulic conductivity at the tracheid level, at 25 µm resolution. A rationalised model was designed for the organisation of tracheids and the water transport through lumina and bordered pits. Within this, pressure drops at flow along lumina and at passages of pits are estimated and integrated to provide local estimates of lumen and xylem conductivities with same radial resolution. The estimated lumen conductivities varied from maximum 0.030 m 2 /(s·MPa) in earlywood to minimum 0.001 m 2 /(s·MPa) in latewood. Estimated pressure drops on pit passages reduce these values with about 80 and 90 % into xylem conductivities of 0.006 and 0.0001 m 2 /(s·MPa) in same earlywood and latewood. Sample means of modelled trunk xylem conductivities were correlated with data from laboratory analyses, resulting in R 2  > 0.50.

Hemicellulose-rich extracts obtained by pressurised hot water extraction of wood residues show promise as emulsion stabilisers. However, pressurised hot water extracts (PHWEs) from wood also contain lower molecular weight extractive components that may influence emulsion performance. This study investigated the effect of extractives on emulsion stability using PHWEs obtained from spruce and birch sawdust with or without solvent pre-extraction. The results indicated that extractives negatively affect the physical stability of emulsions in both spruce and birch and influence oxidative stability in spruce after prolonged storage. However, the roles of different extractives in emulsion performance require further investigation.

The hazards of dust are receiving increasing attention with the application of bamboo industrialization. This study focuses on the morphological characteristics and formation mechanisms of milling dust from raw bamboo, dried bamboo, and thermally modified bamboo treated at varying temperatures. The particle size distribution, area-equivalent diameter, minimum Feret diameter, aspect ratio, roundness, and convexity were investigated. A new method combining sieving and image scanning analysis was applied to identify the size and morphology of the dust. The study has found that thermal modification significantly affects particle size and distribution, impacting dust convexity and surface characteristics. Particle size has a greater impact on dust morphology compared to heat treatment temperature. Thermal treatment is shown to degrade hemicellulose, reducing bamboo’s transverse mechanical properties and thereby altering the generated dust. The three-step cutting process is established, including bamboo milling deformation and dust formation by finite element simulation. This study offers a reference for optimizing dust removal ports and enabling real-time adjustments to dust removal system power based on dust morphology.

Solid dispersion materials of abietic acid (ABA) were prepared with methylcellulose (MC), hydroxypropyl methylcellulose (HPMC), and sodium carboxymethylcellulose (CMC-Na) using a conventional solvent evaporation method. In these materials, ABA was incorporated in an amorphous form. During dissolution tests, ABA from ABA/MC and ABA/HPMC solid dispersion materials initially rapidly dissolved, followed by a decrease in the dissolution rate before eventually plateauing. The dissolution of ABA from ABA/CMC-Na solid dispersion materials was similar, although it increased slightly with an increased shaking time over a long period. ABA from ABA/MC solid dispersion materials exhibited a higher dissolution rate compared with ABA from both ABA/HPMC and ABA/CMC-Na solid dispersion materials. The amount of undissolved material from ABA/cellulose derivative solid dispersion materials was lower compared with ABA/cellulose nanofiber and ABA/TEMPO-oxidized cellulose nanofiber solid dispersion materials. In addition, both ABA/MC and ABA/HPMC solid dispersion materials exhibited good growth-inhibitive effects against Trametes versicolor , a representative of white-rot fungus, compared with ABA/CMC-Na, ABA/cellulose nanofiber and ABA/TEMPO-oxidized cellulose nanofiber solid dispersion materials. Consequently, MC proved to be the most effective water-soluble carrier for ABA in water among the cellulose derivatives tested.