Volume 79, Issue 8

Development of transgenic lignocellulosic biomass with increased cell wall accessibility could benefit development of resource efficient biorefinery concepts. Transgenic callose enriched aspen, reported to show an increased cell wall mesoporosity including increased cellulose-lignin distance and improved accessibility to enzymatic hydrolysis, has been assessed for its behaviour in industrially relevant decoupling processes: autohydrolysis mediated extraction and kraft pulping (not performed in sequence). Under mild autohydrolysis conditions (130 °C, initial 20 min of extraction) and during initial mild phase of kraft pulping (10–20 min) this modification indeed led to a modestly but consistently enhanced extractability of wood components of slightly higher molar mass. These results point out the potential of the callose enriched wood for new prospects of mild resource efficient biorefining.

The West Indian drywood termite, Cryptotermes brevis , causes large economic impacts by consuming wooden structures. The complexity of the lignocellulosic matrix presents many challenges to termites, who have evolved methods to tolerate recalcitrant components. Chemical variations among wood species and the ability of C. brevis to consume them remains understudied. This work compared the chemical composition of hoop pine ( Araucaria cunninghamii ) and shining gum ( Eucalyptus nitens ) before (whole wood) and after ingestion (frass) by C. brevis . Holocellulose content in hoop pine declined from 58.7 % of the original wood to 10.9 % in frass, while shining gum holocellulose content decreased from 55.7 % to 12.5 % in the frass. Reductions in hemicellulose were 62 % and 38 %, respectively, while >90 % reductions in α-cellulose were observed within either wood source. Klason lignin levels were similar in wood and frass for both diets. The total extractives did not differ between wood and frass, but specific compounds varied independently. The results suggest the C. brevis gut and/or its microbiome primarily utilised carbohydrate components while essentially disregarding lignin and extractives. The results improve the understanding of how wood sources affect termite activity and may advise future material choices for improved pest management.

Wood’s hygroscopicity causes it to shrink and swell in response to changes in ambient humidity, which impact its performance in service. This study aimed to elucidate the hygro-deformation behavior of wood by conducting a two-dimensional visualization analysis of intra-ring transverse shrinking and swelling of Chinese fir [ Cunninghamia lanceolata (Lamb.) Hook.]. By combining digital image correlation with Greenhill theory, off-axis deformations were measured and analyzed, demonstrating the method’s capacity to visualize intra-ring dimensional changes. The predicted radial and tangential deformations, derived from off-axis measurements, aligned closely with experimental values. The two-dimensional analysis revealed significant differences in hygro-deformation between earlywood and latewood: earlywood exhibited a “peanut shell” like strain distribution, with most shrinking and swelling occurring in the tangential direction, whereas latewood displayed a nearly circular strain distribution with reduced anisotropy. These findings provide a basis for understanding the deformation behavior of rift-sawn boards and offer valuable insights for optimizing wood processing, drying, and dimensional stability control.

The effectiveness of DMDHEU (1,3-dimethylol-4,5-dihydroxy ethylene urea) modification is influenced by factors such as pore size distribution. In this study, ultrasonic-assisted-alkali pretreatment combined with DMDHEU impregnation was used to enhance the hygroscopic dimensional stability of Ailanthus altissima wood. The weight percentage gain (WPG), absolute dry density, tangential swelling, resin distribution, and chemical functional groups were analyzed. The results showed a marked reduction in the tangential swelling of DMDHEU-ultrasonic-4 % NaOH-pretreated samples, decreasing from about 2.0 % and 4.9 % in untreated samples (without any pretreatment or DMDHEU impregnation) to 0.6 % and 3.2 % at approximately 11.3 % and 75.3 % RH, Respectively. Compared to untreated samples, DMDHEU-ultrasonic-pretreated samples exhibited increased WPG, Absolute dry density, and dimensional stability. Ultrasound-assisted pretreatment also influenced resin distribution within vessels, with raised-membranous resin formations observed in the DMDHEU-ultrasonic-4 % NaOH-pretreated samples, in contrast to the sporadic deposition in untreated samples. Furthermore, XPS and ATR-FTIR results indicated ultrasonic pretreatment facilitated deeper DMDHEU resin penetration into the wood cell wall, converting hydrophilic hydroxyl groups into hydrophobic ester and ether bonds. These findings underscore the significance of ultrasonic alkali pretreatment in enhancing the efficacy of DMDHEU modification for A. altissima , contributing to improved durability and expanding potential applications for this fast-growing timber species.

Pulp fiber lengths are important in the mechanical behavior of paper and paperboard materials. The length affects the total number of bond sites in fiber networks and thus indirectly the paper strengths. In a case study at Mölnbacka Sweden, fiber lengths of wood samples from 38-year-old trees of Norway spruce ( Picea abies ) with fast height growth were investigated. The fiber length of the samples was compared with literature values, and some reference example material. The hypothesis was that the sampled trees with fast height growth may have longer fibers, and thus provide longer pulp fibers, compared to lengths previously reported. The work highlights and critically examines the impact of different preparations, measurements, and analysis methods of fiber lengths. The results from this study show that the 21-year-old sampled wood had longer fibers than expected when compared to previous reports for Norway spruce wood grown in Sweden. The samples also showed to have skewed distributions with proportionally more long fibers than expected, also shown by higher mode values to describe central tendencies. About 75 % of the manually measured Mölnbacka fibers were longer than 3.1 mm with a mode value of 3.77 mm.