JournalTOCs

Journal of Wood Science
Journal Prestige (SJR): 0.536

Citation Impact (citeScore): 1
Number of Followers: 3

This is an Open Access Journal

Open Access journal
ISSN (Print) 1611-4663 - ISSN (Online) 1435-0211
Published by SpringerOpen

[228 journals]

Studies on pre-treatment by compression for wood impregnation III: effects
of the solid content of low-molecular-weight phenol formaldehyde resin on
the impregnation
- Abstract: Abstract There is increasing interests in the significant improvement of impregnation amount and efficiency in wood by the pre-treatment of compression. Thus, attention is paid to pre-treatment by compression for harder impregnation with resin because of the large viscosity and relatively large molecular weight of the resin. Low-molecular-weight phenol formaldehyde (PF) resin of solid content of 10–48% were impregnated by pre-treatment of compression at a compression ratio of 60% and 40% for poplar and Chinese fir, respectively, to systematically study the effects of solid content on the impregnation amount, weight gain percentage (WGP). In addition, the distribution of resin in wood was analyzed by profile density and was observed by confocal laser scanning microscope (CLSM), and the change of crystallinity index (CrI) of resin-impregnated wood was investigated by X-ray diffractometer. The results showed: (1) compared with immersion impregnation without compression, the impregnation by pre-treatment of compression, was much larger in amount and higher in efficiency for resins in all solid contents. In a solid content range of 10–48% and at a molecular weight of about 517, there was no significant difference of impregnation amount by compression among the resins at different solid content. (2) The WGP of poplar and Chinese fir increased with the increase of resin solid content. When the resin solid content increased from 10 to 48%, the WGP increased from 8.9 to 44.2% and from 5.2 to 24.9% for poplar and Chinese fir, respectively. (3) Resin is mainly distributed in vessels and tracheids despite a few being distributed in the fiber near the longitudinal end of the poplar specimens. With the increase of solid content, the resin distribution gradually changed from diffusing on the wall to depositing in the vessel or tracheid, while the resin distribution evenness along the longitudinal direction decreased. There was more resin deposited near the longitudinal end of Chinese fir at deeper depth than that of poplar. (4) The resin can be impregnated into the amorphous area of wood without causing any change in the crystallization area. The CrI decreases with the increase of resin solid content. After all, it is concluded that the pre-treatment by compression for wood impregnation with low-molecular-weight PF resin is effective for all the solid contents for both poplar and Chinese fir. The WGP increased with the increase of resin solid content, despite the decrease of evenness of resin distribution at high solid content.
  PubDate: 2022-05-13
Marker-free genome editing in the edible mushroom, Pleurotus ostreatus,
using transient expression of genes required for CRISPR/Cas9 and for
selection
- Abstract: Abstract In a previous study, we reported a transient transformation system using repeated screening for hygromycin B (Hyg) resistance in the basidiomycete Ceriporiopsis subvermispora. In the present study, by combining this technique with CRISPR/Cas9, we demonstrated successful marker-free genome editing in Pleurotus ostreatus, which is one of the most economically important cultivated mushrooms as well as a model white-rot fungus. At first, transformant selection mediated by the transient expression of marker genes was demonstrated using a plasmid harboring the Hyg resistance gene (hph) in P. ostreatus. Then, genome editing of fcy1, which confers 5-fluorocytosine (5-FC) resistance to the host cell, was performed by the transient expression of Cas9, gRNA, and hph and strains with 5-FC resistance and Hyg sensitivity were isolated. Additionally, genome editing of fcy1 in these strains was confirmed by Sanger sequencing. To our knowledge, this is the first report of marker-free genome editing through the transient expression of Cas9, gRNA, and hph in agaricomycetes, which opens the door for repeated genome editing in these fungi.
  PubDate: 2022-05-12
Estimation of carbon stocks in harvested wood products of buildings in
Japan: flux-data method and direct inventory method
- Abstract: Abstract In this study, carbon stocks in harvested wood products (HWPs) of buildings in Japan were estimated using the direct inventory method, which is highly accurate, and the flux-data method, which was proposed by the Intergovernmental Panel on Climate Change (IPCC) and is commonly used worldwide. We analyzed the differences between the estimated results and the respective reasons. The results indicate that the flux-data method greatly underestimated the carbon stocks in HWPs of buildings in Japan. In 2019, the values estimated by the flux-data method were only approximately 64% of those estimated by the direct inventory method. The half-lives of HWPs and the estimated continuous rate of change in industrial roundwood consumption proposed by the IPCC were likely the main causes of this difference. As for the decay function, the first-order decay, which is a default function proposed by the IPCC, was considered reliable for the estimations, because the decay function was not the main cause of the obtained difference.
  PubDate: 2022-05-09
Effect of temperature on color changes and mechanical properties of
poplar/bismuth oxide wood alloy during warm-press forming
- Abstract: Abstract Binderless poplar/bismuth oxide wood alloy is prepared using the warm-press forming technology. The effect of the forming temperatures on color changes and mechanical properties of the poplar/bismuth oxide wood alloy is studied. The results show that the surface color of the specimen gradually darkened as the forming temperature increased. There is the most obvious change from 140 to 160 °C. The CIE lightness color coordinate L* and chroma coordinate b* decrease with the increase of the forming temperature, while chroma coordinate a* decreases initially, but later increases with treatment severity. The static bending strength (MOR), the elastic modulus (MOE) and the surface hardness (HV) increase first and then decrease with the increase of the forming temperature. The X-ray diffraction (XRD) analysis shows that the wood underwent carbonization at 180 °C, resulting in a decrease in the density and mechanical properties of poplar/bismuth oxide wood alloy, and a deepening of the surface color. The Fourier transform infrared spectroscopy (FTIR) analysis reveals that the pyrolysis of cellulose and hemicellulose, as well as the pyrolysis and condensation of lignin led to the color of poplar/bismuth oxide wood alloy deepening. The hydroxyl groups between the cellulose molecular chains are reduced and hydrogen bonds are formed at 140 °C, which improve the mechanical properties of poplar/bismuth oxide wood alloy. However, the massive degradation of hemicellulose weakens binding strength with cellulose and lignin at 160 °C above. It greatly reduces the mechanical properties of specimen.
  PubDate: 2022-05-03
Radial variations of broad-sense heritability in wood properties and
classification of load–deflection curves in static bending for six
half-sib families of Chamaecyparis obtusa
- Abstract: Abstract Wood properties (annual ring width, tracheid length, microfibril angle [MFA], basic density, and air-dry density) and mechanical properties (modulus of elasticity [MOE], modulus of rupture [MOR], bending work, and compressive strength) in 34-year-old Chamaecyparis obtusa trees of six half-sib families were measured from pith to bark to clarify radial variations in inheritance of these traits and the relationships between wood properties and mechanical properties. In addition, within-tree and among-family differences in the load–deflection curves were discussed. Radial variations of all wood properties were fitted to linear or nonlinear mixed-effects models with random effects of families. The MFA was correlated with MOE in all radial positions, whereas air-dry density correlated with all mechanical properties in mature wood. Radial variations in broad-sense heritability differed between wood properties. A relatively higher broad-sense heritability was recognized in almost all wood properties for mature wood. Based on the results, it was concluded that mechanical properties in mature wood can be effectively improved using MFA and air-dry density as criteria. In addition, the types of load–deflection curve in mature wood differed from those in juvenile wood, suggesting that not only elastic properties, but also plastic properties in C. obtusa are affected by genetic controls, especially in mature wood.
  PubDate: 2022-04-28
Possibility of using the tips obtained from the “Uradome” of moso
bamboo (Phyllostachys pubescens) as a food source
- Abstract: Abstract In the cultivation of bamboo shoots in snow-covered areas, uradome is known to prevent snow damage. Although tips can be obtained by uradome, these are currently considered unutilized. Like bamboo shoots, uradome has the potential to be a source of food. Therefore, to explore the possibility of using uradome tips as food, we evaluated their egumi and umami taste, investigated the free amino acid content, and compared these parameters with those of bamboo shoots. The results showed that the egumi taste of uradome tips was weaker than that of bamboo shoots. The umami taste at first taste was weaker than that of bamboo shoots, while the umami and richness that remained after swallowing was stronger than that of bamboo shoots. The presence of a total of 18 free amino acids was evaluated in the uradome tips and bamboo shoots, and 17 free amino acids were detected in the samples, with cystine being the exception. Eleven of these free amino acids were found to be more abundant in the uradome tips. In addition, eight of the nine essential amino acids (excluding tryptophan) were found in the uradome tips and were in approximately the same amounts as in the bamboo shoots. Furthermore, leucine, a commonly known branched-chain amino acid, was present only in the uradome tips. Overall, the results suggest that uradome tips could be used as a food source.
  PubDate: 2022-04-18
Microwave complex permittivity and anisotropy of conifer wood chips vs
moisture content: experiments and modeling
- Abstract: Abstract The complex microwave permittivity—including anisotropy- of wood chips of softwood has been measured for different moisture contents in the band 0.75 to 2.5 GHz using an ultra-wide band radio transmission technique. The real and imaginary parts increase monotonically with moisture content. The wood chips are oriented by gravity, which gives anisotropic permittivity. The anisotropy ratio of the real part increases from 1.1 to 1.6 with moisture content from 0 to 120%. The anisotropy ratio of the imaginary part is around 2.5 at all moisture contents. Effective medium models were used to model the permittivity. The Bruggeman, and two versions of the Maxwell Garnett model gave good results at low moisture content (below the fiber saturation point). Above the fiber saturation point only the Bruggeman model gave results in agreement with experiments. The difference in model performance suggests that the free water does not follow the wood chips geometry.
  PubDate: 2022-04-14
Optimization of production parameters of particle gluing on internal
bonding strength of particleboards using machine learning technology
- Abstract: Abstract The particleboard (PB) production is an extremely complex process, many operating parameters affecting panel quality. It is a big challenge to optimize the PB production parameters. The production parameters of particle gluing have an important influence on the internal bond (IB) strength of PB. In this study, using grey relation analysis (GRA) and support vector regression (SVR) algorithm, a prediction model was developed to accurately predict IB of PB through particle gluing processing parameters in a PB production line. GRA was used to analyze the grey relational grade between the particle gluing processing parameters and IB of PB, and the variables were screened. The SVR algorithm was used to train 724 groups of particle gluing sample data between six particle gluing processing parameters and IB. The SVR model was tested with 181 sets of experimental data. The SVR model was verified by 181 sets of experimental data, and the values of mean absolute error (MAE), mean relative error (MRE), root mean square error (RMSE), and Theil’s inequality coefficient (TIC) of the model were 0.008, 0.017, 0.013, and 0.014, respectively. The results showed that the prediction performance of the nonlinear regression prediction model based on GRA–SVR is superior, and the GRA–SVR prediction model can be used to real-time predict the IB in the PB production line.
  PubDate: 2022-04-09
Densification of timber: a review on the process, material properties, and
application
- Abstract: Abstract Timber densification is a process that has been around since the early 1900s and is predominantly used to enhance the structural properties of timber. The process of densification provides the timber with a greater mechanical strength, hardness, abrasion resistance, and dimensional stability in comparison to its virgin counterparts. It alters the cellular structure of the timber through compression, chemical impregnation, or the combination of the two. This in turn closes the voids of the timber or fills the porosity of the cell wall structure, increasing the density of the timber and, therefore, changing its properties. Several processes are reported in literature which produce densified timber, considering the effect of various parameters, such as the compression ratio, and the temperature on the mechanical properties of the densified timber. This paper presents an overview of the current processes of timber densification and its corresponding effects. The material properties of densified timber, applications, and possible future directions are also explored, as the potential of this innovative material is still not fully realised.
  PubDate: 2022-03-30
Sequent periderm formation and changes in the cellular contents of phloem
parenchyma during rhytidome development in Cryptomeria japonica
- Abstract: Abstract The outer bark that includes sequent periderms is referred to as rhytidome. The defense and physiological functions of rhytidome are maintained by the continuous formation of sequent periderms. To understand the mechanisms of rhytidome growth, we examined the development of sequent periderms and the corresponding changes in the cellular contents of phloem parenchyma cells in Cryptomeria japonica. New layers of rhytidome were formed in the studied trees during the two-year course of the study. Our records showed that a new layer of periderm forms annually, and therefore, rhytidome development in C. japonica can be studied by sequential sample collection in any given year. Formation of new periderm and initiation of nuclei disappearance in phloem parenchyma in the outer layers of the developing outer bark occurred simultaneously. The early disappearance of nuclei indicates that some parenchyma cells might have been in a stage of preparation for cell death before the formation of new periderm. Four developmental stages of annual rhytidome growth were identified by structural and physiological changes of the outer layers of phloem parenchyma and the growth of the new periderm.
  PubDate: 2022-03-27
Minor cutting edge force contribution in wood bandsawing
- Abstract: Abstract As the sawmill industry is moving towards thinner bandsaws for higher yields, it is important to study the cutting force in more detail. The cutting force can be split into two zones. Zone I concerns the force on the major cutting edge as well as the friction force on the major first flank. Zone II considers the forces on the minor cutting edges as well as the friction forces on the minor first flanks. Zone II cutting can significantly affect the cutting force and has not been studied in great detail. Frozen, non-frozen and dry heartwood of Norway spruce and Scots pine were cut using different tooth geometries and the cutting force was measured. The major cutting edge, clearance, band thickness, minor cutting edge angle and minor cutting edge clearance angle were investigated. The y-intercept of the cutting force–width graph was used as the Zone II force (at this point the Zone I forces are assumed to be zero). The Zone II force contribution to the cutting force was studied. The results show that frozen wood has less elastic spring-back and therefore less Zone II cutting. Dried wood showed a significantly higher degree of Zone II cutting (55−75% contribution to the cutting force). Changing the major cutting edge from 2.87 mm to 1.6 mm resulted in 10–15% higher Zone II force contributions.
  PubDate: 2022-03-19
Spatial distribution characteristics of the dust emitted at different
cutting speeds during MDF milling by image analysis
- Abstract: Abstract Wood dust produced in medium-density fiberboard (MDF) processing is a major occupational hazard in wood industry and may damage processing equipment. In many wood processing factories, dust collecting systems need to be optimized for the distributional and morphological characteristics of dust in the workshop so that economical and efficient dust control can be achieved. In this study, weighting, image analysis and scanning electron microscopy (SEM) were applied to explore the effects of different cutting speeds on the distribution and morphology of dust generated in MDF milling. The results showed that most dust particles were less than 100 μm and that the aspect ratios (AR) were between 0.6 and 0.7. There was significant difference in particle number size distribution (PNSD) between the dust at different sampling positions. Less amount of dust was located close to cutting center, and fine dust was more likely to appear far away from cutting center. Cutting speed was associated with PNSD, but had little effect on AR. The findings provide spatial distribution characteristics of MDF dust during milling, which can be helpful for optimizing cutting parameters and locating dust collecting hoods to minimize dust exposure.
  PubDate: 2022-03-17
Cellular-level in planta analysis of radial movement of minerals in a
konara oak (Quercus serrata Murray) trunk
- Abstract: Abstract After the Fukushima Daiichi Nuclear Power Plant accident, radiocesium, one of the main radioactive materials, has been accumulated inside konara oak trunks. Radiocesium has been thought to move radially through the trunk, but it has not been scientifically vindicated because the mechanism of the radial movement of minerals has not yet been experimentally determined. In this study, mineral radial movement was investigated in konara oak trunks of standing trees. A stable isotope cesium (Cs) solution was injected as a tracer into the outer sapwood of standing konara oak tree trunks. A trunk part was subsequently freeze-fixed with liquid nitrogen and subjected to Cs distribution analysis using cryo-scanning electron microscopy/energy-dispersive X-ray spectroscopy. By comparing normal samples that included living cells and freeze–thaw treated samples that contained no living cells, it was concluded that the injected Cs has been moving through the sapwood by the combination of rapid symplasmic movement by virtue of the living xylem parenchyma cells and slow apoplastic diffusion. Conversely, the Cs solution did not diffuse from the sapwood to the heartwood, implying that Cs is exuded from the living parenchyma cells to the apoplast, i.e., cell walls or adjoined dead parenchyma cells in the layer at the sapwood–heartwood boundary, and then diffused into the heartwood. By integrating the results of this study and our previous results obtained on Japanese cedar, we conclude that the mechanism of the radial movement of minerals through the sapwood seems to be a universal characteristic of tree species. In contrast, since mineral concentrations varied among tree species, the movement mechanism across the sapwood–heartwood boundary can differ among tree species.
  PubDate: 2022-03-14
Flexural vibration properties of particle board using acrylic emulsion
adhesives with differential glass transition temperature
- Abstract: Abstract Vibration characteristics of wood-based materials are essential parameters in considering the indoor environment of a building. This study investigates the effect of the physical properties of water-based adhesives on vibration characteristics of wood-based materials. Adhesive films and particle boards (PB) were prepared from acrylic emulsion adhesives (AE) with differential glass transition (Tg), and loss tangent of dynamic viscoelasticity (tanδD) and flexural vibration property (tanδF) were compared. The tanδD master curve and tanδF showed a similar tendency regarding frequency dependence. The apparent activation energy (ΔH) calculated from the shift factor of the master curve tends to be different depending on the Tg of AE and was especially high for AE with Tg = 13 °C along with blended AE. The dynamic Young’s modulus (EF) calculated from the flexural vibration tests showed higher values for AE at Tg = 13 °C, 41 °C, and 90 °C than that of urea–formaldehyde adhesive (UF).
  PubDate: 2022-03-12
Physiological and psychological responses to olfactory simulation by
Taiwania (Taiwania cryptomerioides) essential oil and the influence of
cognitive bias
- Abstract: Abstract Taiwania (Taiwania cryptomerioides) is a valuable raw material in the wood products industry in Taiwan. An empirical study of the physiological and psychological effects of smelling Taiwania contributes to an understanding of the properties of interior wood that could potentially promote the use of wood materials in a healthy living environment. Prior studies have indicated that pre-knowledge of odors can cause cognitive bias and different responses in subjects. Designed to disclose the therapeutic effects of Taiwania’s scent and its extension to environmental health promotions, this study aimed to (1) investigate its effects on human health responses by stimulating olfaction, and (2) explore the role of cognitive bias in exposure to the scent of Taiwania. The results showed Taiwania’s volatiles had a relaxation effect in reducing the heart rates of participants. Some negative mood states, such as confusion, fatigue, and depression were suppressed. Regarding sensory perceptions, participants reported Taiwania’s scent induced greater affective scores of stimulation, excitement, firmness, distinctiveness, activity, and denseness, but a lower feeling of pleasantness. There were significant effects of positive cognitive bias on reducing the anger-hostility feeling of participants, but no effects on physiological responses. Moreover, the positive information bias alleviated the unpleasantness toward the smell.
  PubDate: 2022-03-03
Alkali-activation of cellulose nanofibrils to facilitate surface chemical
modification under aqueous conditions
- Abstract: Abstract In this study, we developed a surface-activation technique for cellulose nanofibrils (CNFs) using mild-alkali and aqueous conditions. CNFs were initially processed using the aqueous counter collision (ACC) method to produce Janus-type amphiphilic CNFs with both hydrophilic and hydrophobic faces on the surface of a single nanofibril (ACC-CNF). Selective functionalization of the hydroxy groups on the hydrophilic faces creates an opportunity to develop novel nano-building blocks that introduce heterogeneous and tailored surface characteristics into the design of nanomaterials. In this study, alkaline conditions were used to activate the hydroxy groups on the surface of ACC-CNFs as a pre-treatment for the partial crystalline transformation from cellulose I to cellulose II. We found that alkali treatment with sodium hydroxide (NaOH) solutions (concentration range 1–7 wt%) did not fully transform the structure of ACC-CNFs into cellulose II, nor change the morphology of nanofibrils, as seen from their wide-angle X-ray diffraction patterns and atomic force microscopy images. We also found that the hydroxy groups at the surface region of the ACC-CNFs were sufficiently reactive under the moderate alkali and aqueous conditions to undergo subsequent carboxymethylation. Therefore, alkali treatment of ACC-CNFs with a 1–7 wt% NaOH solution rendered the surface of the ACC-CNFs as sufficiently reactive for chemical modification without morphological changes. This simple method for surface activation of CNFs can be useful in the development of future sustainable and novel materials for a variety of applications.
  PubDate: 2022-03-03
Wood identification of Japanese and Chinese wooden statues owned by the
Museum of Fine Arts, Boston, USA
- Abstract: Abstract Precious cultural assets of East Asia are found worldwide and hold many important art-historical meanings, for example Buddhist statues. In this study, we conducted wood identification of Japanese and Chinese statues owned by the Museum of Fine Arts, Boston, USA. From the eight Japanese wood sculptures and one Chinese sculpture, 15 samples were collected. The anatomical features of these 15 samples were scrutinized using synchrotron X-ray microtomography or conventional optical microscopy. The results showed that the eight Japanese statues were made from Chamaecyparis obtusa, except for the base of one Japanese statue that was made from Cryptomeria japonica. Both species are important conifers in Japan. In contrast, the Chinese statue was made from hardwood, Paulownia sp.
  PubDate: 2022-03-03
Characterization of mercerized cellulose nanofibrils prepared by aqueous
counter collision process
- Abstract: Abstract Cellulose nanofibrils (CNFs) obtained by aqueous counter collision (ACC) methods have amphiphilic Janus-type properties, which appear markedly for ACC–CNFs prepared from bacterial nanocellulose (BNC) pellicles. The amphiphilic Janus-type surface is exposed because of the mechanism involved in ACC pulverizing of cellulose materials, in which the predominant interactions of the (2 0 0) lattice plane of the cellulose I crystal structure are weak interplanar van der Waals interactions. Such selective cleavage is more likely to occur for highly crystalline BNC. This study focused on alkali-mercerized cellulose samples, which are of lower crystallinity than BNC. The mercerized raw materials were subjected to ACC treatments and their fiber morphologies, crystallinities, and surface properties were compared to those of ACC–CNFs from native samples. In particular, the Wide-angle X-ray diffraction (WAXD) results suggested that the cleavage was most likely to occur at the (1 1 0) plane in nanofibrils derived from cellulose II, unlike (2 0 0) lattice plane for the case of cellulose I. Accordingly, the entire results indicate that the properties of the ACC-treated mercerized CNFs differ greatly from those of conventional ACC–CNFs composed of cellulose I crystalline structure. This is presumably because ACC nanopulverization proceeds depending on the surface structure and crystalline morphology of the raw material.
  PubDate: 2022-03-03
Structural basis of lignocellulose deconstruction by the wood-feeding
anobiid beetle Nicobium hirtum
- Abstract: Abstract The details of the lignocellulose deconstruction processes in the digestive systems of wood-feeding insects remain elusive. This study aimed to examine the biochemical conversion of lignocellulose in the digestive system of a wood-feeding anobiid beetle, Nicobium hirtum, one of the most important pests of wooden products in Japan. To this end, N. hirtum larvae were fed with Japanese red pine (softwood) and Japanese beech (hardwood) sapwood diets, as well as an artificial diet containing Shorea wood (hardwood) sapwood sawdust. The structural differences between the original and digested (feces) lignocellulose samples were examined using wet-chemical and two-dimensional (2D) nuclear magnetic resonance (NMR) methods. Cellulose and hemicelluloses, especially mannan in the softwood diet, were preferentially degraded over lignin in the larval digestive system. As a result, lignin was enriched in the digested lignocellulose residues. Lignin compositional analyses based on thioacidolysis and 2D NMR determined that the proportions of oxidized lignin aromatic units were notably increased after digestion. Further, the 2D NMR analyses revealed the accumulation of aldehyde and hydroxypropiovanillone/syringone end-unit structures in lignin, indicating that oxidative and/or reductive modifications of lignin polymers occur in the larval digestive system. Such structural alterations of lignin may facilitate the dissociation of the lignin barrier, thereby liberating polysaccharides for subsequent enzymatic conversion for assimilation and energy.
  PubDate: 2022-02-21
Embedment properties of Japanese cedar (Cryptomeria japonica) treated with
resin impregnation
- Abstract: Abstract To strengthen the embedment properties of wood, this study applied the resin impregnation technique, which fills the resin into wood cells. The urethane prepolymer and acrylic monomer were selected in this study. A mechanical test by a round steel bar loaded to the wood specimen was conducted. The characteristics showed higher values in the resin-impregnated groups than in the control specimen group, especially in the stiffness. The urethane- and acryl-impregnated group showed 3.78 and 2.27 times the stiffness values of the control groups in the parallel-loaded condition, and 1.94 and 1.24 times those of the control group in the perpendicularly loaded condition, respectively. Although the stiffness was significantly increased, there was a lack of ductility, which seems to be a serious problem for construction application.
  PubDate: 2022-02-20