Volume 77, Issue 4

A firm understanding of the early selection efficiency of ring width and wood quality traits is a prerequisite for breeding of higher growth rates and wood quality of slash pine ( Pinus elliottii Engelm.). To accomplish effective early selection for the studied traits, wood core samples were collected from 360 trees of 20 open-pollinated families from three slash pine rotation-aged (harvest age) genetic trials. Wood cores were measured by SilviScan, and the annual patterning, heritability, age-age genetic correlation and efficiency of early selection for ring width, modulus of elasticity (MOE), microfibril angle (MFA) and wood density for early to reference age (age 27) were investigated. The greatest annual ring width was observed at age 4, and this trait decreased gradually toward the bark. Different radial trends were found for MOE and MFA. Wood density was lowest near the pith and then increased steadily with age. Overall, heritability was moderate to high for all area-weighted wood quality traits. Very high age-age genetic correlation values were observed for all traits researched. Estimates of efficiency for early selection indicated that the optimal age of early selection for ring width was 9–12 years, while that for area-weighted MOE, MFA and wood density was 7–8 years.

Ginkgo biloba L. saplings were cultivated in an airtight growth chamber with 13 CO 2 for two months. The 13 C ratio of the newly developed xylem region was ca. 85%, evaluated by high lateral resolution secondary ion mass spectrometry and thioacidolysis/GC-MS. Quantitative solid-state 13 C direct polarisation/magic angle spinning (DP/MAS) NMR measurements with high-speed MAS of 70.0 kHz were conducted for cutting-milled wood (CMW), ball-milled wood (BMW), and enzymatically saccharified lignin (EL) samples. In addition, quantitative liquid-state 13 C NMR measurements were carried out for EL in DMSO- d 6 . Major lignin aromatic signals were classified into three groups of aromatic carbons of C–H, C–C, and C–O, and their area ratio was compared within these measurements. EL samples in solid- and liquid-state showed nearly the same results. However, the results for CMW and BMW in solid-state NMR suggest the structural alteration of lignin within the sample preparation procedure, including ball milling.

To address the low accuracy of non-destructive detection of moisture content (MC) of logs (especially in small diameters) by ground penetrating radar (GPR) signals, the MC of 10–15 cm diameter spruce, Manchurian ash, and white birch logs were predicted using the time-frequency parameters of the GPR signals and a back-propagation neural network (BPNN) model. B-scan signals were obtained using tree radar on the barks of discs selected from fresh green logs. Then, 31 time-frequency parameters from the B-scan signals were optimised using the least absolute shrinkage and selection operator (Lasso) and principal component analysis (PCA). Finally, the log MCs of the single and hybrid models was predicted using the BPNN. The accuracy of the least absolute shrinkage and selection operator and back-propagation neural network (Lasso-BP) were higher than those of the principal component analysis and back-propagation neural network (PCA-BP), and the BPNN. The individual species and hybrid models both have good predictive capability; when the log MC is below 20%, the maximum residual errors are relatively small, almost within 6% and 10%, respectively. These models significantly improve the accuracy of non-destructive detection of log MC and are beneficial for efficient wood processing.

This study aimed to clarify the effect of the interactions between the swelling liquid and wood constituents on the creep behavior during drying. Creep tests were conducted during drying of four sample groups (untreated, acetylated, delignified, and hemicellulose-extracted samples) that were swollen using water, one organic liquid, or water-organic mixtures. The largest creep deformation was measured for the hemicellulose-extracted samples, followed by delignified, untreated, and acetylated samples. Apart from the acetylated samples, all treated samples tended to have large creep deformation in water-organic mixtures. For the acetylated samples, the creep deformation was small, except in case of acetone. These differences in the creep deformation behavior are mainly due to the differences in the glass-transition temperature of lignin as a result of the interaction between the wood constituents and the swelling liquid. The considerable increase in creep deformation due to hemicellulose-extraction suggests that hemicellulose, which interacts with lignin and cellulose, reduces the fluidity of the wood due to liquid desorption during creep measurements.

The purpose of this study is to examine the effect of wood aging on the mechanical behavior at the cell-wall level. Synchrotron X-ray diffraction (XRD) measurements were performed to investigate the mechanical behavior of cellulose in the S 2 layer of aged wood from a 250-year-old attic cabin beam. XRD measurements under uniaxial loading were performed on the cellulose (004) plane; the results were compared with those of recent wood. The cellulose in aged wood exhibited a delayed response to both tensile and compressive loading compared with recent wood. Under compressive loading, cellulose showed an increase in maximum strain and a significant increase in the variation of cellulose orientation angle, indicating that it may exhibit buckling-like meandering behavior. These results could be explained based on the decrease in hemicellulose content in the cell wall due to wood aging. In other words, the results suggested that an amorphous material in the cell wall affected the mechanical behavior of wood at the cell-wall level.

Hygrothermal recovery (HTR) is an irreversible dimensional change that occurs when green wood is heated under wet conditions. Reaction wood presents a substantial dimensional change owing to HTR. In this study, the HTR of reaction wood was examined to understand the mechanisms of HTR. This study aimed to elucidate the HTR of tension wood, and particularly its temperature dependency. Two types of analyses were applied to the data measured, namely the two-phase exponential model and the time-temperature superposition analysis. The two-phase model was well fitted to the data and showed that the evolution of HTR could be divided into initial recovery and subsequent continuum contraction. The intensity of the initial recovery increased with increasing temperature. Continuum contraction was not well characterized in this study. Time–temperature superposition analysis provided an apparent activation energy of 326 kJ/mol, which suggests that HTR is a lignin-related phenomenon. A simulation based on the analysis also simulated HTR behavior at ambient temperature in a standing tree.

Wood in marine environments requires protection against xylophagous, and to increase the effectiveness of the preservatives, it is first necessary to know environmental conditions and species of wood borers present. The durability of treated Pinus taeda wood against the attack of marine borers in different environments was investigated, with (1) burnt oil, by the hot-cold bath method; (2) paraffin, by the Bethell method; (3) superficial burning of the wood with oil application, known as shou sugi ban technique; and (4) impermeable rubber, with and without the addition of silica, by immersion. The experiment was adapted from the standard EN 275 (1992) and carried out in three areas, one located in a river and two in estuarine coastal areas of the Paranaguá Bay (Brazil). Based on the percentage of lost wood area, the treatment with impermeable rubber with the addition of silica showed the best performance at the local 1 site (26.3%). At the local 2 site, treatments with impermeable rubber with and without the addition of silica had the lowest percentages of loss, with mean values of 13.95 and 12.65%, respectively. The other treatments had losses above 30%, being classified as severe damage, meaning they are not suitable for this use.

The high polymer and low wood content of current transparent wood has limitation in the mechanical strength and hence obstruct green sustainable transition of the building industry. In this study, a novel method for manufacturing transparent wood was reported by minimizing the usage of polyethylene glycol using partial impregnation followed by a densification approach. The delignified wood was firstly partially impregnated by polyethylene glycol, and subsequently compressed to eliminate pores for the compressed transparent wood, providing the strong hydrogen bonds and dense structures for transparent wood. The wood content of the novel compressed transparent wood was dramatically increased to 64%, compared with the uncompressed transparent wood of 25%. Additionally, the obtained compressed transparent wood demonstrated satisfactory optical transmittance, suitable thermal energy storage, and superior mechanical strengths owing to the formation of densely packed microstructures. This novel, sustainable, and low-cost transparent wood was easy to be manufactured while having increased mechanical and energy-saving characteristics compared to those available in the existing market.