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<jats:title>Abstract</jats:title><jats:p>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.</jats:p>

<jats:title>Abstract</jats:title><jats:p>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 <jats:italic>L*</jats:italic> and chroma coordinate <jats:italic>b*</jats:italic> decrease with the increase of the forming temperature, while chroma coordinate <jats:italic>a*</jats:italic> 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.</jats:p>

<jats:title>Abstract</jats:title><jats:p>In order to promote the development of environmental protection, and the usage rate of green energy utilization, a progressive, innovative laser process method employing helium assisted is proposed, which optimizes the joint cutting process under the same energy consumption. This method provides a new idea for the wood process industry. The uniqueness of this paper establishes a mathematical model to address the diffusion of helium injection and the heat transfer of the laser beam on the processed surface. From the results, it can be exhibited that the oxygen concentration reduces when the helium is injected on the processed surface. The helium could destroy the combustion-supporting conditions and decrease the combustion zone of the processed joint cutting. Thus, the carbonized area of the processed surface is reduced, which could effectively enhance the processing quality of joint cutting. Notably, the helium with injection speed forms a sweeping effect on the processed surface, which could remove parts of the carbonized particles and residues on the processed surface, as well as improve the processing quality. Comparing the traditional laser process and helium-assisted laser process, the gas-assisted laser process owns higher process quality than that of traditional laser processing and cutting. In detail, it features the advantages of smaller joint cutting width, lower surface roughness and smoother surface. Eventually, a mathematical model based on the response surface method with the evaluation criteria of the kerf width, kerf depth, and surface roughness is established to analyze the interaction of laser power, cutting speed and inert gas pressure on the response factors. Comparing the error between the predicted and experimental measurement value, and the optimized process parameters could be acquired. In this paper, the helium-assisted laser process method proposed is meaningful and encouraging, which not only obtains better processing quality, but also provides a guide for developing green industry.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Wood attributes are important, because they directly affect the price persistence of wood products. Consumers consider the “aesthetic,” “traditionality,” “decay resistance,” and “scarcity” attributes important when evaluating wood. This study analyzed the impact of these four attributes on the price persistence of acoustic guitars. We obtained data from a Japanese internet auction platform and winning-bid data for two representative brands, Martin and Yamaha. We performed a quantitative analysis using the winning bid price as the dependent variable and the adoption of various wood attributes in each part of the guitar corresponding to the four attributes as explanatory variables. We found that rosewood, mahogany, palisander, and ebony have a significant impact on price persistence, and that all of them fit the four attributes of traditionality, decay resistance, scarcity, and aesthetics. We also found that traditionality was the key attribute among the four. Using wood in luxury brands without traditionality was not effective, even if other attributes were present. For mass-market brands, scarcity and decay resistance had positive effects on price persistence. The finding that scarcity and decay resistance were important only for mass-market brands can help companies understand market demand, determine product attributes, and achieve product–market fit.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Promoting wood utilization from fast-growing tree species is one solution to address supply and demand issues relating to wood resources while sequestering carbon dioxide in large quantities. Information on the quality of wood from fast-growing tree species and its relationship with changes in stem size is essential for promoting the establishment of plantations and wood utilization of fast-growing tree species. To explore the relationship between the xylem maturation process and radial growth increments of stems in fast-growing tree species, we examined radial variations in annual ring widths and wood properties in <jats:italic>Liriodendron tulipifera</jats:italic> in Japan. The cambial ages at which current annual increment and mean annual increment values were greatest were 4.9 years and 7.4 years, respectively. Based on radial variations evaluated by mixed-effects modeling of wood properties, all properties increased or decreased near the pith before becoming stable towards the cambium. Changing ratios of multiple wood properties at 1-year intervals became stable after a cambial age of 9 years. These results point to an ecological strategy in <jats:italic>L. tulipifera</jats:italic>, in which there is a tradeoff between radial growth increments and wood properties. As part of this strategy, in response to competition among individual trees within a stand, the tree produces a large volume of xylem with lower physical and mechanical properties, allowing it to increase its volume faster than that of the surrounding trees. Subsequently, it produces xylem that is more stable, with greater physical and mechanical properties. This wood forms at a slower growth rate compared to the xylem that forms at the time of initial tree growth. Based on the ecological strategy adopted by <jats:italic>L. tulipifera</jats:italic>, wood that forms before a cambial age of 9 years can be used for utility applications, and wood that forms after a cambial age of 9 years can be used for structural applications.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Exudates are involved in the defense mechanism of trees; they could work against insects or microorganisms through a physical or chemical system. The main components of exudates are terpenoids. This study identified the main compounds of exudates from 13 conifers of Taiwan using gas chromatogram–mass spectrometry (GC–MS) and spectroscopic analysis. The results revealed that the main volatiles were α-pinene, β-ocimene, β-pinene, sabinene, and caryophyllene. On the other hand, the main nonvolatile compounds were diterpenoids, which were classified into three skeletons (abietane-, labdane-, and pimarane-types). Among these, abietane-type presented in Pinaceae and in most of Cupressaceae; labdane-type presented in Pinaceae and in all of Cupressaceae and Araucariaceae; pimarane-type existed in both Pinaceae and Cupressaceae. Furthermore, the epigenetics of conifers analysis results by GC–MS and heteronuclear single quantum coherence (HSQC) of nuclear magnetic resonance (NMR) fingerprints were similar to traditional taxonomy classification; it indicated that exudates chemotaxonomy by using GC–MS and HSQC profiling is a useful technology to classify the conifers. Besides, the exudates of <jats:italic>Pinus elliottii</jats:italic>, <jats:italic>Pinus taiwanensis</jats:italic>, <jats:italic>Calocedrus macrolepis</jats:italic> and <jats:italic>Chamaecyparis formosensis</jats:italic> possessed the strong antifungal activity. For white-rot fungus, <jats:italic>Trametes versicolor</jats:italic>, <jats:italic>Pinus morrisonicola</jats:italic>, <jats:italic>Chamaecyparis obtusa,</jats:italic> and <jats:italic>Araucaria heterophylla</jats:italic> exhibited the higher antifungal index. For brown-rot fungus, <jats:italic>Laetiporus sulphureus, Pinus elliottii</jats:italic>, <jats:italic>Pinus morrisonicola</jats:italic>, and <jats:italic>Chamaecyparis formosensis</jats:italic> revealed a good antifungal activity.</jats:p>

<jats:title>Abstract</jats:title><jats:p>To establish a facile methodology for the elucidation of the lignin chain-growth mechanism, the preparation of monolignol that does not show NMR signals in the dehydrogenative polymer (DHP) was attempted. As a monolignol of which aliphatic moieties were deuterated, coniferyl alcohol-<jats:italic>d</jats:italic><jats:sub>7</jats:sub> was successfully synthesized from protocatechualdehyde and malonic acid via the modified Knoevenagel–Doebner reaction and the Luche reduction. The process achieved high to excellent deuteration efficiencies at the aimed positions (i.e., methoxy: &gt; 99%D, α: &gt; 99%D, β: 92%D, and γ: 98%D). DHP was prepared solely from coniferyl alcohol-<jats:italic>d</jats:italic><jats:sub>7</jats:sub>, and its NMR spectra were compared with those from coniferyl alcohol. The results indicated that: (1) the deuterium atoms at methoxy group, α- and β-positions were highly retained even in the DHP, and their signals were effectively suppressed; (2) a part of the deuterium at γ-position was replaced with H through the reaction; (3) meanwhile, the formation of γ-CH<jats:sub>2</jats:sub> was negligible. This study demonstrated that coniferyl alcohol-<jats:italic>d</jats:italic><jats:sub>7</jats:sub> could “silence” the majority of the signals even when converted to DHP. Highly deuterated monolignols can be a unique molecular tool that can differentiate the signals of interest from those derived from monolignols.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Water stress has a significant impact on tree growth. However, the effects of watering on cambial activity and its influence on tree growth in subtropical climates is poorly understood. The present study analyzed the cambial activity on the stem of evergreen hardwood <jats:italic>Samanea saman</jats:italic> in response to either high frequency or low frequency watering during the pre-monsoon season in subtropical Bangladesh. We used two groups of seedlings: one group of seedlings was watered daily (high frequency watering), while the second group of seedlings was watered at 4–5-day intervals (low frequency watering). Samples for sequential observations of cambial activity by microscopy were collected from the main stems of seedlings of both groups. At the start of the experiment on March 25, 2015, during the pre-monsoon season, the cambium was inactive with no evidence of cell division. After 10 days of high frequency watering, cambial cell division and xylem differentiation were initiated. New cell plates were formed in the phloem side of the cambium. However, the cambium was inactive when low frequency watering was supplied. Supplying water in high frequency reactivated the cambium with forming small to large vessels. In contrast, the cambium remained inactive when low frequency watering was supplied throughout the experiment. These results suggest that continuous supply of water to the soil is one of the most important factors for cambial reactivation during pre-monsoon season in subtropical trees. Furthermore, our findings of artificial watering treatments might help to better understand the response of cambium to changes in precipitation patterns under natural conditions, allowing us to learn more about how cambium of subtropical trees responds to climate change.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Japanese cedar, <jats:italic>Cryptomeria japonica,</jats:italic> is an evergreen conifer native to Japan and is often used as a building material. The humidity control properties of wood are known, but there have been few detailed analyses of its effects on living organisms. Therefore, we investigated the effects of cedar water-soluble components on human macrophages, which are essential for maintaining biological homeostasis and innate immunity. In this study, we prepared aqueous extracts from <jats:italic>Cryptomeria japonica</jats:italic> in Yoshino, Nara prefecture (called as Yoshino cedar). Yoshino cedar aqueous extracts stimulated macrophages toward the classically activated phenotype and inhibited the macrophage phenotype thought to mediate allergic responses. Next, we measured the lipopolysaccharide (LPS) concentration in the Yoshino cedar aqueous extract and found it was present at a high concentration. The major receptor of LPS is Toll-like receptor 4 (TLR4). To confirm whether LPS in Yoshino cedar aqueous extracts activate macrophages through the LPS/TLR4 pathway, we analyzed its effects on TLR4-deficient mouse embryonic fibroblasts (MEF) and wild-type (WT) MEF. TLR4-deficient MEF did not produce the proinflammatory cytokines seen in WT MEF. This result showed that LPS in the Yoshino cedar aqueous extracts activate macrophages via TLR4. This information will help us better understand the benefits of cedar for human health, including allergies.</jats:p>

<jats:title>Abstract</jats:title><jats:p>In this study, with data obtained from a particleboard factory, screw withdrawal strength (SWS) values of particleboards were estimated using artificial neural networks (ANNs). Predictive control charts were also created. A total of seven independent variables were used for the ANN model: modulus of elasticity (MoE), surface soundness (SS), internal bond strength (IBS), density, press time, press temperature, and press pressure. The results showed that the ANN-based individual moving range (I-MR) and cumulative sum (CUSUM) control charts created for SWS values detected out-of-control signal points close to those of the real-time control charts. Among the selected independent variables, IBS was the most important parameter affecting SWS. The most suitable press temperatures and times for high SWS values were determined as 198–201 °C and 165–175 s, respectively. Moreover, the boards with 2500–2800 N/mm<jats:sup>2</jats:sup> MoE and 0.55 N/mm<jats:sup>2</jats:sup> IBS values exhibited the best SWS.</jats:p>