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Aiming at the problems of low milling efficiency, low machining precision and high manual labor intensity of the outer frame of passive European-style wood windows, a double end milling machining center for passive European-style wood windows was designed and used for high-efficiency and high-precision milling of the outer frame of passive European-style wood windows. Through the analysis of the milling process of wood windows, the detailed design of the machining center structure was carried out using computer-aided design methods. Solidworks software was used for three-dimensional modeling of the machining center, and finite element analysis software was used to analyze the strength and stiffness of the key support parts. Virtual experimental methods was used to verify the machining efficiency of the machining center. The results showed that the theoretical machining efficiency of the machining center was about 400 fans/ day, compared with the manual machining efficiency of 350 fans/ day, the efficiency was improved by 14. 28%, and the maximum stress of the key support parts was far less than the permissible stress of the material, which met the requirements for use. [ABSTRACT FROM AUTHOR]

In order to explore the effect of heat treatment of vegetable oil wax on the physical properties and dimensional stability of wood of different tree species, Abies nephrolepis Maxim., Larix gmelinii and Diospyros celebica were taken as the research objects, and the independently prepared vegetable oil wax solution was used as the heating medium. The wood was heat treated at different temperatures (140, 170, 200 ℃ ) for 4 hours, and then the vegetable oil wax was fully cooled to ensure that it entered the interior of the wood. The internal structure was observed by scanning electron microscope. The results showed that the room temperature cooling stage was the key of wood oil wax heat treatment. At this stage, a large amount of vegetable oil wax entered the interior of wood, which was mainly reflected in the change of wood specimen weight percentage gain (WPG). The maximum color change (ΔE ∗ ) of three kinds of wood after combined heat treatment with vegetable oil and wax were 48. 24, 40. 67, 5. 95. The surface hydrophobicity was improved steadily, and the water contact angle (WCA) was increased to about 70°. The tangential and radial moisture expansion rates and volume expansion rates of different tree species were reduced to varying degrees, and the anti swelling efficiency (ASE) was effectively improved, with the maximum increase of 49. 64%, 48. 24% and 38. 86% for the three kinds of wood, indicating that vegetable oil wax heat treatment can improve the dimensional stability of wood. [ABSTRACT FROM AUTHOR]

In order to explore the effect of heat treatment of vegetable oil wax on the physical properties and dimensional stability of wood of different tree species, Abies nephrolepis Maxim., Larix gmelinii and Diospyros celebica were taken as the research objects, and the independently prepared vegetable oil wax solution was used as the heating medium. The wood was heat treated at different temperatures (140, 170, 200 ℃ ) for 4 hours, and then the vegetable oil wax was fully cooled to ensure that it entered the interior of the wood. The internal structure was observed by scanning electron microscope. The results showed that the room temperature cooling stage was the key of wood oil wax heat treatment. At this stage, a large amount of vegetable oil wax entered the interior of wood, which was mainly reflected in the change of wood specimen weight percentage gain (WPG). The maximum color change (ΔE*) of three kinds of wood after combined heat treatment with vegetable oil and wax were 48. 24, 40. 67, 5. 95. The surface hydrophobicity was improved steadily, and the water contact angle (WCA) was increased to about 70°. The tangential and radial moisture expansion rates and volume expansion rates of different tree species were reduced to varying degrees, and the anti swelling efficiency (ASE) was effectively improved, with the maximum increase of 49. 64%, 48. 24% and 38. 86% for the three kinds of wood, indicating that vegetable oil wax heat treatment can improve the dimensional stability of wood. [ABSTRACT FROM AUTHOR]

In order to solve the problem of the influence of fiber dissociation strain rate on the dynamic properties of wood, the ring -porous Fraxinus mandshurica and diffuse-porous birch were used as test materials, with the strain rates of 0. 001, 400, 700, and 1 000 s -1, under fully saturated conditions and with loading directions of radial, tangential, and axial directions. The dynamic mechanical properties of the two test materials were tested, and the effect of strain rate on the dynamic characteristics of wood was analyzed. The research results showed that there was a positive correlation between strain rate and wood dissociation degree. After dissociation, Fraxinus mandshurica of ring-porous wood appeared slender while birch of diffuse-porous wood appeared short and thick. Radial direction in Fraxinus mandshurica of ring-porous wood was most easily dissociated, while tangential direction in birch of diffuse-porous wood was most susceptible. Under high strain rate loading, both Fraxinus mandshurica of ring-porous and birch of diffuse-porous woods' stress-strain curves were divided into the elastic stage and the stage of weak linear strengthening after yielding, with the non-uniformity of internal structure greater in Fraxinus mandshurica of ring-porous wood than in birch of diffuse-porous wood. The compressive strength of the two specimens increased with the increase of strain rate. The results found that the dynamic properties of Fraxinus mandshurica of ring-porous wood and birch of diffuse-porous wood had strong strain rate sensitivity, and they were both strain rate sensitive materials. [ABSTRACT FROM AUTHOR]

:To solve the problem that practical applications of devices in the field of moisture generation are limited by complex preparation processes and high material costs, we developed an environmentally friendly, low-cost wood-based moisture generator (W -MEG) by a simple modified process. Firstly, the wood was delignified using a 2. 5% sodium chlorite (NaClO2 ) solution to keep its natural water transport channels open. Secondly, we prepared sodium alginate / reduced graphene oxide (SA/ rGO) hydrogels with excellent moisture absorption and ion diffusion ability and coated them onto the wood surface. Finally, to further improve the power generation performance of the prepared W-MEG, the degree of hydrogel immersion into the internal channels of the wood was controlled by adjusting the time of the reduced pressure impregnation process to form an asymmetric structure with more top and less bottom, which further expanded the ion concentration distribution. Based on this asymmetrical structure, taking advantage of wood's natural directional water transport properties and ion diffusion effects, our W-MEG can generate an open-circuit voltage of 220 mV and a short-circuit current of 0. 28 μA at 80% relative humidity (RH), with a power output in the RH range of 35%-95%. In addition, by integrating multiple W-MEG units, it can be used as an efficient power source to drive miniature commercial devices such as LEDs, which has the potential for practical applications. This study provides new insights into simple, inexpensive and efficient moisture energy harvesting devices and enables novel technologies for the utilization of wood. [ABSTRACT FROM AUTHOR]

As an environmentally friendly physical modification of wood, wood heat treatment technology can effectively improve wood color, dimensional stability and biological durability of wood, so it is widely used in the functional improvement of wood. In this study, Castanopsis hystrix wood was used as the research object, water vapor was used as the heating medium and the wood was heat treated for 1. 5-4. 5 h under the temperature of 150-210 ℃ . The color changes of Castanopsis hystrix wood under different hear treatment conditions were studied, and the correlation between color and dimensional stability, mechanical properties and biological durability was also discussed. The results showed that the lightness index L ∗ decreased, the red green index a ∗ and the yellow blue index b ∗ increased slowly, and the lightness difference ΔL ∗ and the total color difference ΔE ∗ increased gradually, indicating that the color of heat treated Castanopsis hystrix wood gradually changed from primary color to dark color. The maximum reduction of dry shrinkage rate and wet expansion rate was 55. 7% and 69. 7%, respectively, indicating the dimensional stability was obviously improved. The flexural strength and elastic modulus were decreased by 3. 1%-30. 2% and 3. 7%-20. 7%, respectively. The termite resistance and rot resistance grade were not improved. In the temperature and time range involved in this experiment, there was a second-order parabolic relationship between the color change of heat-treated wood and the weight loss rate of termite-eaten wood, the survival rate of termite, and the weight loss rate of brown rot wood and white rot wood. However, the correlation between the color change of heat-treated Castanopsis hystrix wood and dimensional stability and bending resistance was unclear. Therefore, it is feasible to predict and evaluate the anti -biological durability of heat treated Castanopsis hystrix wood by color change. [ABSTRACT FROM AUTHOR]

The macroscopical and microscopical structures of Dalbergia latifolia wood were observed by means of biological digital microscope and continuous ploidy microscope. The morphological characteristics of various cells were determined and analyzed. The surface contact angle was measured by static drop contact angle measuring instrument. The results showed that D. latifolia wood was a loose pore wood. The main conduit cells were single and diameter multiple conduit holes. The cylindrical conduit cells were the most, accounting for 50. 08% of the conduit cells, and the length to width ratio was 1. 17. Most of the wood fibers were spindly and tough fibers with a length-width ratio of 38. 28. Wood ray cells were common recumbent ray cells with a length-width ratio of 5. 74. The axial parenchyma was abundant, pterygoid, clustered pterygoid, intermittent narrow band, ring bundle, containing a few compartmentalized crystalline cells, cell length to width ratio of 4. 43. The maximum cell tissue ratio was 71. 10% of wood fiber. The minimum was 0. 11% of compartmentalized crystalline cell, and the order from large to small was: wood fiber cells, xylem ray cells, vessel cells, axial parenchyma cells and crystal cells. The surface contact angle of D. latifolia in 40 s changed 18. 02°, decreased by 30. 83%. The analysis of the anatomical structure and surface contact angle of D. latifolia wood can provide reference for its identification and utilization. [ABSTRACT FROM AUTHOR]

In the detection of log volume, the accuracy and stability of the intelligent detection system are easily affected by the factors such as end cutting marks, cracks, shadows and so on. For a long time, the end face recognition and positioning is a difficult problem. For this reason, through the principle analysis and experimental verification of multiple YOLO version models, this paper has fused the advantages of multiple YOLO version models. On the basis of the yolo3 backbone network, using data enhancement, feature fusion, loss function and other optimization methods, an end-to-end depth learning model YOLO-Raw Wood (YOLO-RW) is constructed, which is more suitable for log detection and is used for accurate recognition and localization of log volume images. In order to test the performance of the YOLO-RW model, this paper has designed several sets of data experiments. The experimental results show that the YOLO-RW model has higher end face recognition accuracy and robustness than the benchmark model, and is 6. 95% and 2. 38% higher than the benchmark model in terms of preparation rate and recall rate. Therefore, the YOLO-RW model has a good application value in the field of log volume detection, and can also provide a reference for the research of related target recognition fields. [ABSTRACT FROM AUTHOR]

Woody biomaterials are widely available, renewable, and environmentally friendly. The wood adsorbents are classified into five categories: woody biomass, woody activated carbon, wood ceramics, wood aerogel, and woody activated carbon fiber, according to their preparation process methods and physical properties, and according to economic costs, physical properties, and other process characteristics. Investigate the modification of wood adsorbents and their coupling with other treatment methods for removing pollutants from water and enhancing the adsorption of specific pollutants by imparting new properties to the wood adsorbents for specific pollutants. The adsorption isotherm and kinetic models are presented, focusing on the theory of model assumptions and model characteristics. Thereby, the microscopic adsorption mechanism is macroscopically represented through the fitting of adsorption data and points out the problems of some wood adsorbents in removing pollutants from water. [ABSTRACT FROM AUTHOR]

(1) Background--With the implementation of the natural forests total stop-logging policy, the wood raw materials provided by the state-owned forest areas in Northeast China are not enough to support the normal production of wood processing enterprises. The concentration of log and sawn timber import market in the state-owned forest area of Northeast China is too high, and the import market is mainly Russia, the United States, Canada and New Zealand. With the intensification of international trade conflicts in timber forest products, Russia, Turkey, India and other countries have restricted the export of timber resources through tariff and non-tariff measures. Different types of wood processing enterprises, especially the state-owned wood processing enterprises are facing many difficulties and need to explore the transformation strategy. (2) Methods--In this paper, private wood processing enterprises and some forestry bureaus in the stateowned forest areas of Northeast China were used as research objects and 76 valid questionnaires and 20 audio interviews were obtained by using cross-cycle and multi-level investigation methods. Firstly, the audio was converted into text data, and Nvivo12. 0 software was used for word cloud analysis based on the rooted coding theory. In this study, only concepts related to the subject of constraints on the imported timber resources were proposed. Finally, the transformation strategies of wood processing enterprises in the state-owned forest areas of Northeast China was studied and analyzed by using the modeling logic diagram formed by the above data. (3) Results--First, three core categories of resource constraints, cost control and transformation strategies are extracted from the interview records according to the coding results. Resource constraints are the core factor that affect enterprise transformation. Solving resource constraints is conducive to cost control, thus promoting enterprise transformation from different angles. Second, the restrictions on wood imports in international laws and bans and the continuous improvement of domestic ecological sustainable development and construction have led to the gradual deepening of the constraint degree of wood resources on wood processing enterprises. Third, due to the scarcity of resources, the increase in production costs such as procurement costs, storage costs and financing costs of wood raw materials brought about by enterprise production reduces the market price advantage of products and increases the operating pressure and risk of enterprises. Fourth, after the implementation of the natural forests stop-logging policy, the resource constraints in the state-owned forest areas of Northeast China is still at a higher level on the whole, although it is lower than the two crisis periods. (4) Conclusions and Discussions--The transformation paths of enterprises are analyzed from three aspects: diversified development, digital development and marketization development. Several policy recommendations are put forward for different types of wood processing enterprises: First, the wood processing enterprises that rely heavily on wood imports should actively carry out the construction of transportation networks to save transportation costs. Second, the state-owned wood processing enterprises should drive the main business with diversified management and guide the intervention of non-forestry capital to stimulate innovation. Third, small and medium-sized, primary wood processing enterprises should pay attention to improving the degree of agglomeration, in order to play the advantages of cluster. Fourth, wood-based panel processing enterprises and wood products processing enterprises should adopt digital means and integrate intelligent manufacturing in order to improve product quality on the basis of sustainable development. Fifth, the private wood processing enterprises should find the right market positioning based on public demands, in order to improve added value of products and market competitiveness and promote the steady development of enterprises. [ABSTRACT FROM AUTHOR]

Wood is a common renewable resource. Different kinds of wood have different uses and commercial values. The traditional wood classification work mainly depends on manual work, and the work efficiency is low. In order to improve the efficiency of wood recognition, a wood recognition method based on improved EfficientNet is proposed. In this method, EfficientNet is used as the benchmark model, and the large kernel attention module is used to replace part of squeeze-and-excitation networks (SENet) in Mobile Inverted Bottleneck Convolution (MBconv), and combines the two attention mechanisms to enable the network to extract wood fine grain information more effectively. Progressive learning strategy is introduced in the training process, and images of different sizes and Dropout layers with different discarding probabilities are used for training, which further improves the training speed and recognition accuracy of the model. The experimental results show that the recognition accuracy of the improved EfficientNet model can reach 99. 83%, which is 0. 49% higher than that of the unimproved EfficientNet model, and the model parameters are only 6. 16 MB. The proposed model can identify wood species well, and can provide reference for the deployment of wood species identification model in mobile terminal. [ABSTRACT FROM AUTHOR]

The artificially regenerated 2 years Tilia amurensis seedlings under the canopy of the secondary forest were taken as the research object, and two kinds of light (high light (HL, gap) and low light (LL, canopy)) were set, and four treatments excluding underground competition (fertilization (F), root cutting (T), root cutting plus fertilization (T+F), and control (CK)) were used to determine the morphological characteristics and biomass allocation of Tilia amurensis, and to explore the influence of light and underground competition on artificial regeneration of Tilia amurensis. The results showed that, 1) root cutting and fertilization significantly promoted the seedling height and ground diameter growth of Tilia amurensis, among which T and T+F treatments significantly increased the seedling height and ground diameter growth, while light had no significant effect on the seedling height and ground diameter growth. 2) Biomass and specific leaf weight of Tilia amurensis were significantly affected by the interaction of light and measures to exclude underground competition. Among the 8 treatment combinations, T and T+F treatments under HL significantly promoted the biomass accumulation and specific leaf weight of Tilia amurensis seedlings. The seedling biomass and specific leaf weight of T+F treatment under HL were at the maximum values, followed by T treatment under HL. The seedling biomass of CK treatment under LL was higher than that of CK treatment under HL. 3) T+F and T treatments significantly increased the root length, root surface area and root volume of Tilia amurensis seedlings, and T+F treatment increased more significantly than T treatment. Light had no significant effect on the fine root morphology of Tilia amurensis seedlings. In conclusion, artificially regenerated Tilia amurensis under forest canopy, a moderately shaded light environment under canopy was more suitable for the growth and regeneration of Tilia amurensis. When artificially regenerated Tilia amurensis was carried out in the strong light environment such as forest gap, root cutting or root cutting plus fertilization should be supplemented to reduce the competition of upper layer wood roots for soil resources and promote seedling growth. [ABSTRACT FROM AUTHOR]

The biochemical transformation of lignocellulosic biomass is one of the important methods for producing environmentally friendly bioenergy from agricultural and forestry wastes. Among them, lignocellulose is the most important form of biomass energy, and it is one of the important ways of biorefinery to convert lignocellulosic into fermentable sugar by means of biochemical transformation, and further conversion into fuel ethanol and chemicals, which has received extensive attention and research from various countries. In this study, Poplar wood was added to 60% ethanol aqueous solution with a solid-liquid ratio of 1:10 (w/v) with 0.025 mol/L of metal salts (FeCl3, CrCl3, CuCl2, FeCl2, ZnCl2, MnCl2, MgCl2, CaCl2, NaCl and LiCl) at a speed of 300 r/min, and the reaction continued for 10 min at 200 ℃ in a high-pressure reactor. The influence of different metal-salts catalyzed ethanol pretreatment of poplar on the chemical composition, sugar composition, microstructure and enzymatic glucose yield of poplar were studied. Furthermore, the additives (Tween 80, tea saponin, BSA, and xylanase) were added to the enzymatic hydrolysis, the effects of different metal-salts catalyzed ethanol pretreatment and additives on enzymatic hydrolysis of poplar were explored by comparing the glucose yield, resulting in the optimal combination of metalsalt and additive for poplar enzymatic hydrolysis. Through the pretreatment of poplar wood with different metal salts catalyzed ethanol pretreatment, it was found that the degradation of hemicellulose and lignin by trivalent and divalent metal salts was obvious. Through XRD, the crystallinity (CrI) of poplar raw material was 64.14%, and its CrI increased to 78.63%, 78.65%, 78.92%, 77.26%, 75.79% and 70.33% after pretreatment with FeCl3, CrCl3, FeCl2, MgCl2, NaCl and LiCl- catalyzed ethanol. This is because the relative crystallinity of crystalline cellulose in pretreated poplar is increased due to the removal of amorphous hemicellulose and lignin during the ethanol pretreatment process catalyzed by metal salts. It has been found that all metal salt-catalyzed ethanol pretreatment has the effect of promoting enzymatic hydrolysis efficiency. Among them, the trivalent metal salt is better than the trivalent metal salt and the monovalent metal salt as a whole. Through XRD and SEM, it could be seen that the dense structure formed by poplar fiber was destroyed, and the increase of cellulose content led to an increase in its relative crystallinity and exposed more accessible sites, thereby improving its enzymatic hydrolysis efficiency. By analyzing the effects of the addition of four additives on the yield and growth rate of enzymatic hydrolysis of poplar in the pretreatment of metal salt- catalyzed ethanol, it was found that the addition of additive could increase the enzymatic hydrolysis speed, shorten the enzymatic hydrolysis time and increase the enzymatic hydrolysis efficiency. Among them, Tween 80 has the widest application range and better effect on poplar pretreated with metal salt catalyzed ethanol. The addition of Tween 80 to the enzymatic hydrolysis of poplar after pretreatment with FeCl3 -catalyzed ethanol yielded the highest glucose yield of 93.44%. [ABSTRACT FROM AUTHOR]

Biomass pelletizing treatment can enhance the energy density and decrease the transportation and storage cost of the resulted fuel. In the study, wood sawdust (WS) pretreated by hydrothermal and hydrothermal oxidation process at 170～260 ℃ was used to prepare biomass pellet. The effects of the hydrothermal and hydrothermal oxidation pretreatment on the mechanical property and combustion performance of the wood pellet were investigated using Van Soest method, X-ray diffraction (XRD), thermogravimetric analysis (DTG), industrial analysis and oxygen bomb calorimeter. The results showed that the hemicellulose and amorphous cellulose decomposed rapidly at 170～230 ℃, the crystalline cellulose began to decompose at 260 ℃ and the relative mass fraction of lignin gradually increased with an increase of temperature because of the decomposition of hemicellulose and cellulose after hydrothermal pretreatment. While the hemicellulose was completely decomposed before 230 ℃ and the temperature of crystal cellulose decomposition was advanced to 230 ℃ after hydrothermal oxidation pretreatment. Compared with hydrothermal pretreatment, the relative mass fraction of lignin increased more obviously. The pyrolysis characteristics of wood sawdust pretreated by hydrothermal and hydrothermal oxidation were analyzed. It was found that the samples after hydrothermal pretreatment, the height of hemicellulose pyrolysis peak gradually decreased and completely disappeared at 230 ℃. The pyrolysis peak of cellulose first increased and then decreased with the increase of pretreatment temperature, and the peak of lignin was positively correlated with the increase of pretreatment temperature. Compared with hydrothermal pretreatment, with the increase of hydrothermal oxidation temperature, the pyrolysis peak of hemicellulose disappeared obviously； the pyrolysis peak of cellulose showed a downward trend and the peak was significantly advanced while the pyrolysis peak of lignin continued to rise. The hydrothermal and hydrothermal oxidation pretreatments can greatly enhance the mechanical properties of the resulted biomass pellets compared with that of the unpretreated WS pellets. After hydrothermal pretreatment, the apparent density increased from 1 110.2 to 1 381.6 kg/m3 and the compressive strength increased from 16.2 to 38.9 MPa at 230 ℃, which increased by 24.4% and 140.1%, respectively. The apparent density increased to 1 429.2 kg/m³, and the compressive strength increased to 41.1 MPa at 200 ℃ after hydrothermal oxidation pretreatment, which increased by 28.7% and 153.7%, respectively. Compared with hydrothermal pretreatment, hydrothermal oxidation pretreatment can promote the degradation of the hemicellulose and cellulose contained in WS and enhance its mechanical property, thus, the pretreatment intensity can be alleviated. In the process of hydrothermal and hydrothermal oxidation pretreatment, the crystallinity of samples increased first and then decreased with the increase of pretreatment temperature. After hydrothermal pretreatment, the crystallinity of cellulose increased from 41.4% to 50.7% at 230 ℃. The crystallinity of cellulose reached the maximum value at 200 ℃ after hydrothermal oxidation pretreatment which was higher than the maximum value of hydrothermal pretreatment. When the temperature of hydrothermal oxidation pretreatment rose to 260 ℃, the crystallinity finally decreased to none. The mechanical property of the pellets is found to be positively correlated with the change trend of the cellulose crystallinity and the crystalline cellulose is the key component for the biomass pelletizing process. The hydrothermal and hydrothermal oxidation pretreatments can significantly enhance the heating value, the comprehensive combustion characteristic index and combustion stability index of the resulted WS pellets. Compared with hydrothermal pretreatment, the hydrothermal oxidation pretreatment can promote the carbonization degree of the resulted samples. In sum, the quality and combustion performance of the fuel pellet can be improved by the pretreatment. These results can supply some support for the production of good quality WS pellets. [ABSTRACT FROM AUTHOR]

In order to solve the problem of lack of steam source in the humidification process of wood air energy assisted solar drying equipment, this study adopted the process of ‘stuffy kiln drying' (closing the inlet and exhaust channels in the drying equipment, and relying on the evaporated moisture in the wood to increase the humidity of the medium). In order to realize the humidity adjustment in the drying process and ensure the drying quality of poplar. The drying rate, stratified moisture content, elastic strain variation trend and drying quality of poplar sawn wood in the process of ‘conventional drying' (CD) with air energy assisted solar heating and ‘stuffy kiln drying’ (SKD) with air energy assisted solar heating were analyzed by using the method of stratified slice and image analysis. The results showed that the SKD process can improve the humidity of the drying medium in a certain stage during the air energy assisted solar heating drying process. In the range of moisture content from 10% to 120%, the drying rate of SKD was 81.25% of CD, and the drying time was only 22 h longer than 104 h of CD. At the same time, the deviation of moisture content in wood thickness was reduced by 12.05%, which improved the overall drying uniformity of the wood pile degree and dry quality of the wood. [ABSTRACT FROM AUTHOR]

To explore the surface visual characteristics, the influence of microcellular structure on the surface total color difference (ΔE* ) of common softwood in Yunnan, the surface visual physical magnitudes of 50 species of softwood in Yunnan were measured and calculated. Cluster analysis, correlation analysis, and other methods were used to study the distribution characteristics of the surface visual physical magnitudes of 50 species of softwood, the correlation between various visual physical magnitudes, the significance of the influence of microcellular structure on ΔE*, and the processing and utilization properties of wood with different color types. The results showed that the distribution of lightness (L* ) of 50 species of softwood in Yunnan ranged from 42. 02 to 77. 55, the red-green chromaticity index (a* ) ranged from 7. 34 to 18. 18, the yellow-blue chromaticity index (b* ) ranged from 19. 70 to 32. 82, the color saturation (C* ) ranged from 23. 30 to 34. 25, and the hue angle ( h°) ranged from 55. 66 to 73. 48. The a* value was generally low and belonged to the yellow tone range, except for the Taxus which tended to be in the dark reddish-brown tone range. According to the furthest neighbor clustering algorithm, 50 species of softwood were mainly divided into 4 categories. Class I includes Cupressus, Fokienia, Juniperus, Platycladus, Pseudotaxus, Cunninghamia, Metasequoia, and some Pine species. Class Ⅱ includes Taiwania, Picea, and some Pine species. Class Ⅲ includes Taiwania and some Pine species. Class Ⅳ includes Taxus, Juniperus, and Larix from the Larix speciosa. There was a significant negative correlation between L* and a*, h° and a* . There was a significant positive correlation between L* and h°, C* and b* . As for color difference parameters, Δa* and Δb* were significantly positively correlated with ΔC* respectively. Δa* was significantly negatively correlated with Δh°. The influence of the axial parenchyma on ΔE* was significant, and the interaction between the average tracheid length and ray tracheids was significant. [ABSTRACT FROM AUTHOR]

Fusarium oxysporum isolated from natural discolored rubber wood was used to infect rubber wood flakes for 60 d at 28 ℃.It was found that Fusarium oxysporum could discolor rubber wood flakes.Thin slices of discolored rubber wood were studied by infrared spectroscopy, X-ray diffraction analysis and polarized light and fluorescence microscopy.The results showed that infrared spectroscopy and X-ray diffraction analysis revealed varying degrees of change in the chemical composition of Fusarium oxysporum-infested rubber wood flakes, with trace degradation of cellulose, hemicellulose and lignin.Polarizing and fluorescence microscopy showed that the basic anatomical structure of rubber wood flakes infected by Fusarium oxysporum did not change significantly, and only a small amount of cellulose and lignin degradation existed in the pigment and mycelium. [ABSTRACT FROM AUTHOR]

Red soil is one of the most widely distributed soil types in Yunnan Province of China. Red soil is characterized by high plasticity, high void ratio, heavy viscosity, slightly acidic soil, as well as low water and fertility retention. Among them, alternate wetting and drying can be caused by rainfall, irrigation, high-temperature evaporation, and disturbances in production and construction projects, leading to the shrinkage, cracking, and swelling of red soil during drought. Soil water characteristics change dramatically, which is essential to carry out soil improvement in red soil regions. Soil reconstruction has been widely used in the practice of red soil improvement. Most research focuses mainly on the hydraulic properties of the natural red soil, rather than the reconstructed one. Furthermore, the wood fiber can be expected to serve as an ecological soil conditioner, in order to improve the ecological restoration, of the soil, and water conservation in the mining areas. However, it is still lacking on the effects of wood fiber additions on the physical properties of red soil in the combination of dry and wet alternation and wood fiber. In this study, a novel mechanism was proposed to clarify the impact of wood fiber reconstruction on the hydraulic properties of red soil during dry and wet alternation. The red soil was collected in Kunming City of Yunnan Province in China. Four types of wood fiber additions (0, 0.5%, 2.5%, and 5.0%) were used to improve the red soil. The matric suction of wood fiber composite soil was measured using filtering, and the soil-water characteristic curve (SWCC) was fitted using the Logistic model. The results showed that there was a gradually slow hysteresis in the dry-wet alternation on the decrease in the soil matric suction and SWCC of red soil, as the addition of wood fiber increased. Specifically, 2.5% wood fiber composite soil was the optimal ratio to improve soil water holding. The addition of wood fiber increased the intake and residual value of red soil. The residual value changed greatly under dry and wet alternations, whereas, there was a gradual decrease in the residual value, as the number of dry and wet alternations increased. The slope of 2.5% wood fiber composite soil was less affected by the dry and wet alternations, with the best capacity of water holding, while the volumetric water content decreased. The determination coefficients of soil-water characteristic curves were all above 0.97 after wood fiber addition, indicating that the Logistic model was suitable for the SWCC fitting of red soil that was modified with the wood fiber. The finding can provide a strong reference for soil reconstruction and ecological restoration during land consolidation in the red soil regions. A series of experiments were also carried out to determine the different amounts of wood fiber during dry and wet alternation. The relationship was also established between the impact of wood fiber improvement on the hydraulic properties of red soil. Since the specific impact can be depended on the physical indicators of the soil mass, further research can be expected to focus on the soil pore structure, aggregates, and permeability in the red soil. [ABSTRACT FROM AUTHOR]

The experiment was to compare the content of 4-methoxy-5-hydroxycanthin-6-one and 4, 5- dinethoxycanthin-6-one and total alkaloids in different parts of Picrasma quassioides. The content of 4-methoxy-5- hydroxycanthin-6-one and 4,5-dinethoxycanthin-6-one in 14 different parts of Picrasma quassioides were determined by HPLC. The total alkaloid content of each part was measured by ultraviolet spectrophotometry. The results showed that the content of total alkaloids and two alkaloid monomers in stem heartwood and main root heartwood were higher, and the contents of total alkaloids in leaves were high but the content of two alkaloid monomers were lower, The content of 4- methoxy-5-hydroxycanthin-6-one in stem bark, stem sapwood, taproot bark and taproot sapwood was higher but the content of 4, 5-dinethoxycanthin-6-one were lower, The content of 4, 5-dinethoxycanthin-6-one in branch bark and branch wood was higher but the content of 4-methoxy-5-hydroxycanthin-6-one was lower. The study incicates that the content of 4-methoxy-5-hydroxycanthin-6-one and 4,5-dinethoxycanthin-6-one and total alkaloids in different parts of Picrasma quassioides were different, the results can provide a reference for the rational utilization of different parts of Picrasma quassioides in healthy breeding of poultry and livestock. [ABSTRACT FROM AUTHOR]

In order for the support vector machine to accurately identify the surface defects of wood veneer and improve the quality of wood veneer, an efficient and accurate recognition model of kernel principal component analysis (KPCA) gravity search algorithmsupport vector machine (GSA-SVM) for veneer defects was proposed. Considering the redundant effect between image feature data, KPCA method was used to reduce the dimension of original feature data, and GSA optimized the penalty factor C and kernel parameter g of support vector machine (SVM) to establish KPCA-GSA-SVM wood veneer defect recognition model. Based on the three features of color, texture and shape, the raw data set of samples with live knots, dead knots and cracks as the research objects, 8 main features (1 color feature, 1 texture feature and 6 shape features) were selected as the basis for wood veneer recognition. The wood veneer identification model was learned, trained, predicted and analyzed, and the identification effect was compared with the KPCA-PSO-SVM identification model composed of the traditional particle swarm parameter optimization algorithm (PSO). The results showed that the recognition rate of live knots, dead knots and cracks of the wood veneer recognition model based on KPCA-GSA-SVM was 100%, 96. 78% and 100%, which were 21. 62%, 0. 63% and 7. 41% higher than that of KPCA-PSO-SVM, and the overall time was shortened by 7. 26 s, it can be seen that the prediction recognition rate, recognition speed and stability were higher than the former. The research conclusions identify the veneer defects from a new perspective, which is helpful for the identification and development of wood veneer defects. [ABSTRACT FROM AUTHOR]

In this paper, taking the Dalbergia melanoxylon wood as the research object, the macrostructure and microstructure of the wood were observed and analyzed, and the structural characteristic parameters of various cells were measured and analyzed. The results showed that the Dalbergia melanoxylon wood growth rings and ripple marks were less obvious, fine structure and straight texture. Heartwood had dark stripes and was yellowish-brown to purplish-brown. For loose hole material, pipe hole combination type was mainly single pipe hole, a few compound pipe hole, and pipe hole contained dark gum. Axial parenchyma was partubular wing and scattered polymerization. The wood rays were fine wood rays, and the main types of wood rays were homomorphic single row and a few homomorphic multiple row. It was not obvious to the naked eye. Wood fiber was stacked, cavity was small and wall was thick. It had compartmentalized crystalline cells. The highest tissue ratio was 80. 09% of wood fiber, and the lowest was 0. 12% of compartmentalized crystalline cell. According to uniform color space recommended by the International Lighting Commission 1976 CIE (1976 ) L* a* b* and Munsell chromatic space, Dalbergia melanoxylon wood is mainly red and yellow with low saturation, and the color is deep. Through the study of macrostructure and microstructure characteristics of Dalbergia melanoxylon wood, it provides a reference for identification and utilization of Dalbergia melanoxylon. [ABSTRACT FROM AUTHOR]

Industrial integration is one of the key roles in rural revitalization. The level of industrial integration can be classified to evaluate the obstacle factors in the different types of villages, particularly for the decision-making on industrial revitalization. In this study, the measure of industrial integration level was determined to diagnose the obstacle factors in the different planting types of rural areas in the hilly and mountains areas. The survey data was also collected from the 15 sample villages in six towns of Chongqing (Jiangjin) Modern Agricultural Park of China. The evaluation index was constructed from two dimensions, including the industrial integration behavior and integration benefit. The entropy weight and TOPSIS were used to couple the coordination and obstacle degree model for the integrated assessment and obstacle factor diagnosis of rural industry. The results showed that:1) The low overall level of industrial integration was found in the study area, with an average value of only 0.210. Specifically, the integration level was ranked in the descending order of the prickly ash type (0.399) > grain and oil type (0.254) > flowers and woods type villages(0.134) = vegetable type (0.134) > fruit type (0.127). There was also the striking disparity of village in the similar rural industries. The differences in the integration level of the flower-wood, vegetable, and fruit type villages were all lower than 0.110, while the prickly ash and grain-oil type villages were observed in 0.732 and 0.361, respectively, indicating the notably higher than those of the first three types of villages. The coupling and coordination degree of rural industrial integration was mostly at a low level. Fourteen sample villages were in the different degrees of imbalance, accounting for nearly 93.33%. There was the diverse in the coupling coordination degree of the six types of villages, of which the prickly ash type villages (0.436) were the highest, followed by the grain and oil type villages (0.369), and the lowest were the vegetable type villages (0.291), the flower and wood type villages (0.285), and fruit type villages (0.274). Besides, there was also a large gap in the degree of coupling and coordination between similar villages, ranking as the prickly ash type villages (0.372) > grain and oil type villages (0.201) > fruit type villages (0.157) > vegetable type villages (0.098) > flower and wood type villages (0.051). 3) The integrated development of various rural industry was caused by several factors, such as the village proximity, the proportion of new industrialization agricultural operators, the average education years of integrated operators, and the presence or absence of supporting facilities for the industrial integration at obstacle degree level greater than or equal to 0.08. But the influence degree was different. Some recommendations were proposed to improve the input of resource factors, the foundation conditions for industrial integration, and the scope and depth of agriculture. Different plans of integration can be expected in rural areas, according to the own characteristic resources. [ABSTRACT FROM AUTHOR]

Wood vinegar is the liquid obtained by condensation of flue gas generated during the pyrolysis of agricultural and forestry residues. Research on the preparation and application of wood vinegar can improve the utilization rate of agricultural and forestry residues and reduce environmental pollution. In this paper, the effects of pyrolysis temperature on the yield and components of wood vinegar, the effects of different raw materials and refining methods on the components of wood vinegar, the functional components, functions and application directions of wood vinegar prepared from different raw materials were comprehensively expounded by consulting a large number of literatures and materials and combining with the components determined by the authors of this paper. At the same time, the reasons for the difference in wood vinegar yield and composition were analyzed. The research progress of wood vinegar in improving soil physical and chemical indexes and biological activity, promoting crop growth, improving crop quality, controlling pests and diseases, and preparing biomass fertilizer was emphatically introduced from the aspects of different kinds, dilution concentrations, application methods, and combined application with other fertilizers. And aiming at the problems that the active ingredients are not clear in the current research process, the future research direction was presented. [ABSTRACT FROM AUTHOR]

The practical application of metal-organic framework (MOF) crystals is commonly limited by their powder form. In this work, natural balsa wood was employed as substrate for dispersing and shaping MOF particles. A series novel MOF@wood (MOF=UiO-66,ZIF-8 and ZIF-67) composite were successfully fabricated by a facile in situ growth strategy. The microstructure, flame-retardant and methylene blue (MB) dye adsorption behavior of the obtained composite were investigated. The result indicated that the MOF microparticles with different grain sizes and morphologies were uniformly decorated on the lumen surface within the balsa wood scaffold, and MOF crystals maintained its crystallinity in the MOF@wood composite. The ZIF-8@wood composite displays highly removal efficiency up to 82.5%% for methylene blue and the adsorption capacity can reach 210.9 mg/g. Moreover, the adsorption process fits well with a pseudo second-order model, which confirms that the interaction between MOF@wood and MB is mainly controlled by chemical processes.In addition, the incorporation of UiO-66 MOF has better effect on thermal stability at the early stage and char layer formatting of wood substrate than ZIFs.Compared with the untreated wood, the peak of heat release rate of the UiO-66@wood composite exhibited a drastic decline from 94.5 W/g to 36.5 W/g and the total heat release from 7.7 kJ/g to 5.4 kJ/g. Meanwhile, the char residue rate of the UiO-66@wood at 800 ℃ is significantly increased by 84.8%.This work offers a new avenues for designing and constructing functionalized MOF@wood composite that may boost their environmental-and green building-related applications. [ABSTRACT FROM AUTHOR]

Using basic copper carbonate and basic zinc carbonate as raw materials, nanocomposite preservatives (MCZ) were prepared after wet grinding. By blending acrylate emulsion, silicon-containing acrylate emulsion and MCZ, modified MCZ and silicon-containing modified MCZ were obtained, and the rubber wood was treated with modified MCZ by dipping method, and the effect of acrylate emulsion and silicon-containing acrylate emulsion on anti-loss properties of nanocomposite MCZ were studied. The results showed that when the mass ratio of MCZ and acrylate emulsion was 1∶1, the modified MCZ had the best bleed resistance, which was 11. 18% higher than that of MCZ and 5. 86% lower in corrosion resistance (white rot bacteria), but still met the requirements of strong corrosion resistance grade requirements. The nanocomposite preservative modified by silicon-containing acrylate emulsion had lower loss and higher corrosion resistance than acrylate emulsion modified composite preservative. When the silicon content was 4%, the loss rate of the preservative was 2. 4%, and the weight loss rate of treated wood was 4. 43%. The nanocomposite preservative modified by silicon-containing acrylate emulsion had the characteristics of strong loss resistance, good corrosion resistance, safety and environmental protection. This research has a positive role in promoting the development and utilization of environmentally friendly wood preservatives. [ABSTRACT FROM AUTHOR]

Deep learning has been a promising technology for epidemic tree detection in recent years. However, the expensive data annotation has posed a great challenge to the discolored epidemic wood detection in the pine forest. Particularly, some difficulties are still found in the dataset expansion, model generalization ability, and the presence of samples with obscured or small objects during detection. In this study, target detection was proposed for the discolored epidemic wood using semi-supervised learning and Unmanned Aerial Vehicle (UAV) image analysis. The specific procedure mainly included the dataset for the pine forest epidemic wood, semi-supervised model training, and algorithm detection. The dataset was collected from three provinces in China, especially with a total of six epidemic wood forms. Two datasets were randomly and equally divided for the training and testing in the supervised and semi-supervised learning stages, respectively. 2 160 training and 240 testing sets were available after data augmentation. The anti-noise loss (SoftFocalLoss and L1Loss) was classified with the uncertainty indicator for the data distillation. Among them, combating Noise was the most advanced semi-supervised target detection model in the same period. As such, the quality of pseudo labeling was improved effectively. The following improvements were achieved in the Cascade Noise-Resistant Semi-supervised (CNRS) object detection model, compared with the Combating Noise. 1) A cascade network was added to balance the distribution of positive and negative samples during training, in order to equalize the accuracy and over-fitting. 2) The FocalLoss was used to mine the difficult samples in the phase of supervised learning. The improved learning of the model was achieved in the difficult objects, such as the edge objects and early epidemic wood. 3) SmoothL1Loss was used to ensure a relatively stable gradient, particularly for the large difference between the true and the predicted value. 4) Soft-Non-Maximum Suppression (Soft-NMS) was used to soften the rejection process of the detection frame in the RCNN stage, in order to prevent the near targets from being filtered. The experiments were conducted on Ubuntu 18.04 operating system using NVIDIA Tesla P100 graphics processor. The experimental results show that the Average Precision (AP) values were 64.2%, and 85.4%, respectively, for the single-stage detector SSD300 and the two-stage detector Faster RCNN using fully labeled data. 50% of the labeled data was also selected in the semi-supervised model. Both AP values were higher than the fully supervised model, indicating that the anti-noise learning effectively extracted the semantic information from the pseudo labels. The ablation model of CNRS Model1 improved the AP by 0.3 percentage points, where a cascade network was added with the RoI Pooling. Model2 further improved the AP by 0.3 percentage points after the RoI Align. The AP of the optimal model on the test set was 87.7% with an F-Score of 0.669. A comparison was also made on the detection of the four models using 24 test images. The error detection rate of CNRS was compared with the fully supervised network model, and Faster RCNN using fully labeled data. The CNRS presented a 50% reduction in the labeling, and a 2.3 percentage point increase in the AP, which was 1.6 percentage points higher than that of the semi-supervised network Combating Noise. This improved model can also provide reliable data support for pest control in agriculture and forestry. An accurate detection can be achieved in many different forms of epidemic trees and a significant reduction in the data labeling cost. [ABSTRACT FROM AUTHOR]

The study examined the effect of decomposition of fallen wood on soil nutrient content to determine the functional role of fallen wood in forest ecosystems. The data will be a reference for scientific management and formulating protection strategies for forests. Fallen wood of four common tree species (Machilus rehderi, Liquidambar formosana, Cyclobalanopsis glauca, and Platycarya longipes) in mild, moderate, and severe decay classes in Maolan′s karst evergreen and deciduous broad-leaved mixed forests. Soil samples were collected at 10, 30, and 50 cm distance from fallen wood. Soil organic carbon, nitrogen, phosphorus, and potassium contents were determined to reveal the impact of fallen wood decomposition on soil nutrient contents. Tree species, decay class, and their interactions had significant effects on the contents of total nitrogen, hydrolyzed nitrogen, total potassium, total phosphorus, available phosphorus, and organic carbon of soil adjacent to fallen wood (P＜0.05) . Distances and their interaction with tree species and decay class did have significant effects on soil nutrient contents. The contents of total nitrogen, hydrolyzed nitrogen, and organic carbon in the soil adjacent to mildly decayed felled L. formosana wood were significantly lower than those of soil adjacent to other species. The contents of nitrogen, phosphorus, total potassium, and organic carbon in the soil adjacent to severely decayed felled M. rehderi wood were significantly lower than those of soil adjacent to other species (P＜0.05) . In higher decay classes, the contents of nitrogen, phosphorus, and organic carbon in the soils adjacent to L. formosana and C. glauca showed significantly increasing trends (P＜0.05) . These contents in soil adjacent to M. rehderi and L. formosana first increased and then decreased (P＜0.05) . Soil nitrogen, phosphorus, and organic carbon were significantly correlated with each other (P＜0.01) [ABSTRACT FROM AUTHOR]

Interfacial photothermal evaporation is expected to resolve the water shortage, inconvenient water intake, and low water quality in most rural areas. However, the high material cost, complex preparation process, and low evaporation rate of the solar absorber are restricting the development of this novel technique. It has been reported that adjusting the water supply rate on the light-absorbing surface is an important approach to developing an efficient and continuous interfacial photothermal evaporator. In this work, the naturally evolved, porous, and photothermal material of pinus sylvestris was prepared with simple preparation, strong hydrophilicity, and evaporation rate close to the theoretical limit using a one-step hydrothermal method. Subsequently, the solar-driven interfacial water evaporation experiments were conducted to clarify the effects of carbonization degree and water supply height of the photothermal material on the interfacial evaporation performance. The surface temperature and evaporation reduction were considered at the different carbonization temperatures (100, 125, 150, 175, and 200 ), carbonization time ( 2, 4, 6, 8, 10, and 12 h), and the heights of the photothermal material (5, 10, and 15 mm). The underlying mechanism was then determined using the microstructure, element distribution, capillary water transport, and heat transfer. Importantly, the enhanced interfacial water evaporation was enabled by the carbonized wood. The results showed that the original pore structure of the log was retained with the rough surface formed by carbon microspheres after the mild carbonization process. There was a 2.3 temp ℃ erature rise of the evaporation surface, particularly beneficial to the increase of light absorption. Moreover, the proportion of the C-H/C-C bond in the log (51.5%) was higher than that of the C-O-C/C-OH bond (37.7%), whereas, the proportion of the C-H/C-C bond (37.8%) in the carbonized wood was lower than those. It infers that the carbonization process greatly contributed to the log with more hydrophilic groups. This was because the parts of hydrophobic lignin and hemicellulose were removed during carbonization. Therefore, the climbing height of water in the carbonized wood increased from 4.2 to 22.3 mm during the climbing time (120 s). By contrast, the rising heights of water were 3.1 and 9.0 mm in the log and carbonized wood, respectively, indicating the weak capacity of transverse water transport. The data also agreed well with the classical Lucas-Washburn imbibition model. The steady-state evaporation rate of the carbonized wood-based evaporator increased by 130% and 28%, respectively, compared with the water- and log-configured evaporators. The maximum evaporation rate reached 1.24 kg/(m²‧h) at the temperature of 200 after ℃ 8 h carbonization. It was noted that the excessive carbonization formed a bright and smooth surface, leading to the reflection loss of incident light with the reduced surface temperature of the evaporator. As a result, the evaporation rate dropped significantly. More importantly, the sidewall height of the material reduced the average temperature of the evaporation surface, resulting in the reduction of radiative and convective heat losses from the evaporator to the surroundings, thus improving the evaporation rate. Once the sidewall height was 15 mm, the evaporation rate reached 1.48 kg/(m²‧h), and the corresponding solar-to-vapor conversion efficiency was 66.2%. This finding can also provide an important reference for the utilization of agricultural and forestry wastes, particularly for the heat-moisture balance during solar-driven interfacial water evaporation. [ABSTRACT FROM AUTHOR]

The development of composite materials with good acoustic vibration performance is an effective way to alleviate the shortage of wood resources for musical instrument soundboards. To explore the possibility of wood-plastic composite materials applied in musical instrument soundboards, the mechanical properties preparation method of composite materials was used as a reference to study the influence of wood powder content and compatibilizer content on the acoustic vibration performance parameters ( specific dynamic elastic modulus, sound radiation quality constant, acoustic impedance, logarithmic decay rate) of composite materials, and comparison with traditional wood for musical instrument soundboards to determine wood powder and compatibilizer content with superior acoustic vibration properties. The research results showed that the wood powder content had a great influence on the acoustic vibration performance of wood-plastic composites. When the wood powder content increased from 60% to 80%, the acoustic vibration parameters acoustic impedance ω, logarithmic decay rate δ, specific dynamic elastic modulus value of E/ρ increased, and the vibration effect decreased slightly. In the preparation of wood-plastic composite materials, the content of compatibilizer had a great influence on the sound quality of the composite material. When 65% wood powder content was used, the content of compatibilizer accounted for 7% of wood powder content to prepare the composite, a relatively good overall performance of acoustic vibration can be obtained. Compared with the existing soundboard materials for musical instruments, the ω value (2. 21 Pa·s/ m) of the wood-plastic composite material in the experiment was close to that of American spruce (2. 20 Pa·s/ m), and the δ was smaller than that of the wood-carbon fiber composite soundboard, but there was also a problem that the sound radiation quality constant R was smaller than that of the wood-glass fiber composite soundboard, and the specific dynamic elastic modulus was relatively small, follow-up research on this issue should be carried out. [ABSTRACT FROM AUTHOR]

⑴ Background——China is the largest importer and fifth largest exporter of wood forest products, while the United States is the second largest importer and largest exporter of wood forest products in the world. Meanwhile, the US is the largest export and import trade partner of China’s wood forest products. The Sino-US trade friction initiated by the US in March 2018 involves the vast majority of wood forest products. Existing studies mainly focus on the impact of Sino-US trade friction on bilateral wood forest products trade and profit and loss, ignoring its overall impact on China’s international wood forest products trade. Measurement and analysis of the impact of Sino-US trade friction on China’s international trade of wood forest products is helpful for us to take corresponding measures to cope with the challenge of the Sino-US trade friction and ensure stable and healthy development of China’s wood forest products industry and international trade.⑵ Methods——From the three aspects of demand, supply and trade, 8 indicators that may have a great impact on import and 11 indicators that may have a great impact on export are selected. Based on the data from 2002 to 2017,the grey correlation analysis method is used to measure the grey correlation coefficient between different influencing factors and the import and export trade level of China’s overall wood forest products and the import and export trade level of the main wood forest products. Selecting strong correlation indicators to construct Multi-variable Grey Model MGM（1,N）,“Counterfactual reasoning method” is used to measure and analyze the impact of Sino-US trade friction since 2018 on the import and export of China’s wood forest products as a whole and the import and export of main wood forest products.⑶ Results——With the implementation of multiple rounds tariffs imposed by China and the US, under the dual effects of large country effect and the substitution effect of import and export markets, except for paper, paper products and wood products, trade amount and quantity of the import and export of China’s most wood forest products first increase and then decrease significantly. Further research shows that Sino-US trade friction significantly reduces the import cost of China’s main wood forest products, but has a large negative impact on China’s imports of logs and sawn timbers, it endangers China’s wood import safety, and worsens the export trade conditions of China’s main wood forest products, but the impact is quite different. China’s wooden furniture and plywood exports show a bad trend of an increase in export volume and a decrease in export prices. It can be seen that the profits from China’s wood forest products import trade increase significantly, while the profits from China’s wooden furniture and plywood export trade is damaged severely, and the export of China’s wooden furniture and plywood faces severe challenges.⑷ Conclusions and Discussions——China should recognize the positive and negative impacts of Sino-US trade friction, and accelerate the implementation of the “double cycle” strategy while continuing to strengthen the import diversification of logs and sawn timbers, reducing the high dependence on foreign timber resources and changing the export mode of “large quantity and low price” of Chinese wooden furniture and plywood. [ABSTRACT FROM AUTHOR]

【Objective】The study aimed to establish droplet digital detection system and verify the effectiveness of it, in order to provide a more accurate and sensitive method for the detection of Bursaphelenchus xylophilus. 【Method】Genus-specific primers and probe were designed based on 16 S rDNA gene sequence in using online tools for primers and probe design. Optimize the PCR reaction conditions and determine the best reaction conditions of droplet digital detection system. The specificity of this system was detected by using the genomic DNA solutions of 6 strains of B. xylophilus and 12 strains of B. mucronatus, B. thailandae, B. sexdentati, B. dalianensis, Aphelenchoides parasaprophilus, A.resinosi and Cylindrotylenchus pini. The sensitivity of this system was verified by setting different concentration gradients with 10 times diluted standard DNA as a template. The repeatability of droplet digital PCR was detected by three different concentrations of DNA standard dilution templates. Finally, the practicability of this system was verified by using the DNA extract of nematode samples and susceptible pine samples as templates. 【Result】（i）A set of pine wood nematode specific primers and probe were designed which named primers: P1904-F, P2057-R; Probe: Probe-1938.（ii）The optimize annealing temperature of PCR reaction system was determined to be 55 ℃.（iii）The Specificity verification showed that the designed primers and probe could distinguish the B. xylophilus from other similar nematodes.（iv）The results of sensitivity detection showed that the detection concentration of this detection system was between 0.51-20 000 copies/μL.（v）The repeatability test of three groups of standard samples with different concentrations found that the coefficient of variation of this detection system was between 0.31%-9.12%, and the sample concentration was negatively correlated with the coefficient of variation.（vi）Dd-PCR were used to test the wood sample which collected from affected trees and simulation add B. xylophilus, the results has shown that this method can detect B. xylophilus in the samples, moreover, the copy number was positively correlated with the amount of nematodes in the sample. 【Conclusion】In this study, the dd-PCR detection system of pine wood nematode was established. This method exhibit high specificity, high sensitivity, low coefficient of variation, and it can detect B. xylophilus in wood samples with high efficiency. The establishment of this system could provide reliable data for the study of pathology and ecology of B. xylophilus. [ABSTRACT FROM AUTHOR]

Engineered wood-based products including plywood, fiberboard, and particleboard have been largely used in interior furnishing and construction fields, which promotes the rapidly increased consumption of wood adhesives. Formaldehyde-based adhesives such as urea formaldehyde and phenol formaldehyde are the most widely used wood adhesives because of their low cost, excellent bonding performance, and water resistance. Many biomass materials including cellulose, tannin, and lignin have been utilized as main components for developing biobased adhesives, but they mostly show high cost, week bonding strength, and poor water resistance. Plant oils are composed of triglycerides that are intrinsically water resistance, and thus are perfect materials for preparing water-resistant adhesives. As one of the main commercially available plant oil derivatives, Acrylated Epoxidized Soybean oil (AESO) is derived from soybean oil via an epoxidization and acrylation process. AESO possesses the advantages of abundance, water resistance, and environmental friendliness. The development of AESO-based wood adhesives is a novel approach to reduce the consumption of aldehyde-based adhesives. AESO contains carbon-carbon double bonds and hydroxyl groups as well as epoxy groups. Thus, Hexamethylene Diisocyanate (HDI) was introduced as a modifier and tert-butyl Peroxybenzoate (TBPB) was used as a free-radical initiator to prepare the formaldehyde-free AESO wood adhesives and their poplar plywoods. The chemical structure, rheological and curing behaviors, water-resistance, and bonding mechanism of the modified AESO adhesives and their effects on the physical and mechanical properties of the plywoods were investigated. FTIR and NMR analyses confirmed that HDI could react with both the hydroxyl and epoxy groups of AESO to form carbamate structure, hence leading to improved crosslinking density of the adhesives and interfacial bonding between wood and the adhesives. Due to the improved cohesion and bonding force of the adhesives, and the water-resistant bonding strength of poplar plywood was up to 1.18 MPa, which meets the requirement of Chinese standard. The addition of HDI significantly reduced the viscosity and the maximum curing temperature of AESO resins, and improved the processibility of the adhesives. The HDI modification significantly increased the physical and mechanical properties of the plywoods (P<0.05). The bonding strength, flexural strength, elastic modulus, and water resistance of the plywoods significantly increased with the increased mass ratio of HDI to AESO from 0.5:9.5 to 1:9, and then leveled off as the further increased HDI usage. The optimum mass ratio of HDI to AESO was considered as 1:9, in which the transverse flexural strength and elastic modulus of the plywood reached 57.6 MPa and 5 920 MPa, respectively, and the plywood did not crack at 120 °C for 2 h. SEM images indicated that the HDI modification significantly increased the interfacial adhesion between wood and adhesives due to the formation of covalent bonds. The work provides a feasible way to prepare formaldehyde-free adhesives by using biomass soybean oil as raw materials, which is beneficial for the green and sustainable development of wood industry. [ABSTRACT FROM AUTHOR]

Gelatin is a non-toxic and degradable biomass resource, which is a partial hydrolysis prod-uct of collagen, essentially a protein. Gelatin has the advantages of low cost,abundant raw materials, safety and environmental protection, but its mechanical properties and water resistance are poor. In order to expand the application of gelatin, the properties of gelatin can be improved by modification. Adhesives are used in many fields and closely related to daily life as they can bond the same or dif-ferent substrates together. However, harmful substances volatilized during the preparation and use of traditional adhesives, which can harm people's health and pollute the environment. Gelatin itself has a certain viscosity and green,is a natural adhesive material. In this paper, firstly,the structure of ge-latin is summarized,and the advantages and disadvantages of three modification methods of physical modification,chemical modification and blending modification are described; Then,the research pro-gress of gelatin-based adhesive in wood, leather, paper making, medicine and other industries in re-cent years are reviewed; Finally, the future development of gelatin-based adhesive is prospected, which is expected to provide a reference for the further development and research of gelatin in the field of adhesive. [ABSTRACT FROM AUTHOR]

[Objective] The transfer and accumulation characteristics of heavy metal cadmium in soil mulberry system after reclamation in abandoned lead-zinc mining area were revealed. [Method] The mulberry orchard used as the research object in the 14 years of recultivation in the mining area was determined by measuring the leaves, branch bark, branch wood, stem bark, stem wood thick root bark, thick root wood and all fine roots of mulberry trees and total cadmium and available cadmium in soil in mulberry garden. [Result] (i) The distribution ratio of the cadmium accumulation of the whole mulberry plant on the roots, branches and leaves was about 12: 5: 3. (ii) Differences in cadmium content in various tissues and organs of mulberry trees were shown as follows : fine roots > branch bark > stem bark > rough root bark > leaf > rough root wood > stem wood > branch wood. There was significant difference in cadmium concentration between fine roots and stem wood of mulberry, but there was no significant difference among other tissues and organs. The cadmium contents were 0. 21, 0. 13, 0. 11, 0. 10, 0. 09, 0. 04, 0. 03 and 0. 01 mg/kg. (iii) The cadmium enrichment ability of various tissues and organs of mulberry tree was as follows: fine root > branch bark > stem bark > leaf > rough root bark > rough root wood > stem wood > branch wood. The coefficients were 1. 04, 0. 87, 0. 70, 0. 5 6, 0. 53, 0. 23, 0. 16 and 0. 08. (iv) The ability of cadmium to be transported from fine roots to various organs was asfollows: shoot bark section > stem bark section > leaf > stem wood section > branch wood section, and the transfer coefficients were 0. 62, 0. 54, 0. 41, 0.13 and 0. 07. ( v) Low soil available cadmium content was beneficial to the enrichment and transport of cadmium by mulberry trees. [Conclusion] Fine roots are the main part for mulberry to absorb and accumulate cadmium, and the skin is the main way for cadmium migration in mulberry. [ABSTRACT FROM AUTHOR]

(1) Background—China's timber market has developed rapidly since the beginning of the new century. However, China's timber market monitoring information collection lacks a unified standard, which seriously affects the market monitoring ability and level. (2) Methods—From 2016 to 2020, we conduct field research, information collection, and data verification in 11 key timber markets in 9 provinces, a total of 13,267 records of timber product market transaction data have been recorded. Based on these research data and literature results, from the perspective of market monito-ring, the application of information science theories and indicator screening, market surveys and expert consultation methods are used to analyze the factors affecting the timber market and build a monitoring indicator system. (3) Results—The external factors that affect the operation of the timber market include 23 main indicators in four aspects; economic development, laws and regulations, social population, and the international environment. The internal factors include 59 main indicators in 9 aspects; market supply, market demand, market entities, transaction objects, transaction prices, and transaction status, market location, transaction time and market management; internal factors that can continuously reflect and influence the timber market monitoring and constitute an indicator system include 4 aspects, transaction time, transaction location, transaction products and transaction information. The 4 aspects cover 25 specific indicators, a certain date, the administrative area, the trading place, the source of wood, the name of the wood species, the product type, the product grade, the product specification, the total inventory, the stock capital, the total purchase, the purchase price, the total purchase value, the supply volume, total sold, selling price, total selling value, selling on provincial city, provincial sales, balance, gross profit, selling rate, gross profit rate, transaction volume, and transaction amount, which can provide a reference basis for the development of the timber market monitoring system platform, and lay a parameter basis for market analysis. At the same time, there are 13 core indicators that determine the collection of market information are a certain date, trading place, the source of wood, the name of the wood species, product type, product grade, product specifications, total inventory, total purchases, total purchase value, total selling value, and selling on provincial city and provincial sales. This provides basic compliance for the collection template design and market data collection. (4) Conclusions and Discussions—There are many factors affecting the development and operation of the timber market, including external factors such as economic development, laws and regulations, social population, and international environment, as well as internal factors such as market supply, market demand, market entities and transaction objects. And the internal factors are the key points of timber market monitoring. This indicator system refers to relevant research results at home and abroad, and some information elements need to be revised and supplemented. At the same time, the cost-benefit analysis and monitoring effect comparison be-tween different indicator systems, the comparison of indicator screening methods, the analysis of information classification methods, the classification and coding of monitoring indicators, the correlation analysis between independent variables and dependent variables, and the importance of each indicator in the system framework, and other academic considerations such as reliability and validity testing all need to be further strengthened. Moreover, in due course it is necessary to adjust monitoring indicators, add and delete core indicators, and optimize collection templates according to the timber market and regulatory requirements changes. [ABSTRACT FROM AUTHOR]

To compare the differences in wood tracheid morphology and chemical composition, Fokienia hodgirtsii aged 35-43 years from eight provenances in Fujian Province were selected and analyzed. The results showed that the length, width, and aspect ratio of the tracheids were significantly different between the eight F. hodgirtsii provenances. The tracheid length ranged from 1 700 to 3 100 μm, belonging to long fibers, and the tracheid aspect ratio ranged from 50 to 85. Among these provenances, the tracheid length (3 036 μm) and aspect ratio (84.10) were the highest in the provenance of Putian, and the tracheid width (36.1 μm) was the greatest in the provenance of Fuzhou. The chemical composition was significantly different between the eight F. hodgirtsii provenances. The contents of cellulose, lignin, and benzyl alcohol extracts ranged from 28.98% to 44.39%, 12.87% to 22.48%, and 4.57% to 13.25%, respectively. In the provenance of Fuzhou had the highest content of cellulose and the lowest content of phenylphenol extract. The highest lignin content was found in the provenance of Xiamen, while the lowest was discovered in the provenance of Zhangzhou. The wood tracheid morphology and chemical composition of F. hodgirtsii were significantly correlated with the growth traits of tree height and diameter at breast height between the different seed sources; the correlation with the environmental factors of altitude and humus thickness of the seed sources was also significant. [ABSTRACT FROM AUTHOR]

Some prominent characteristics of hyperbranched polymer and its basic application in amino resin were introduced, its application situation in urea-formaldehyde resin, melamine-formaldehyde resin and amino copolycondensation resin used for wood bonding was summarized, and some existing problems of hyperbranched polymer modifing amino resins was analyzed, some relevant development suggestions were put forward. Although there are still many barriers, the application prospect of hyperbranched polymers in wood adhesives will be better and better with the deepening research on hyperbranched polymers. [ABSTRACT FROM AUTHOR]

In order to recognize the knots accurately and reduce the waste of wood, a method of recognizing the knots based on GoogLeNet convolution neural network based on the deep learning framework of Pytorch was proposed in this paper. This method used GoogLeNet network to extract features automatically from RGB images of seven kinds of spruce knots, such as decayed knots, dry knots and encased knots et al, so that classification and recognition can be realized without image preprocessing. Global average pooling was used to replace the fully connected layer, and the network parameters can be reduced. At the same time, in order to prevent overfitting, Dropout mechanism was used in the network. The experimental results showed that, the recognition accuracy of seven kinds of knot defects using the convolutional neural network can reach 95. 42%, and the GoogLeNet can identify the knots accurately and effectively in the image processing of wood knot defects. [ABSTRACT FROM AUTHOR]

In order to study the shear effect of wood-lightweight aggregate concrete specimens connected by bolt keys, static load tests were carried out on 96 sets of 32 types wood-lightweight aggregate concrete shear connectors with electro-hydraulic servo universal tester and TDS data collecting machine. The test results showed when two more bolts were used, shear failure mode of the connectors, belongs to brittle failure; if the bolts were arranged equally, the ductility coefficient of the low intensity of lightweight aggregate concrete LC20 increases and fits out deformation. Considering specimen limit displacement and applying bearing capacities of comprehensive performance, we could get the best performance by the using two of ϕ8 or ϕ 10 type bolts and the intensity of lightweight aggregate concrete is 30 MPa. The results of the study provide reference values for the design and application of wood and lightweight aggregate concrete [ABSTRACT FROM AUTHOR]

Diameter at breast height (DBH), tree height and volume are the most significant factors in forestry investigation. The measurement precision of DBH and tree height directly affects the accuracy of individual volume. In traditional forestry works, cutting down trees and using analytic timber are for compiling the volume tables, which are yet faced with the problems such as high consumption, low efficiency and large destruction. In recent years, the emergence of the modern instruments gradually lays the foundation for achieving high precision nondestructive standing tree measurements. Total station is a kind of precise tool that can be used to measure distance and angle and to process data automatically. And it will be widely used in forestry production practice and scientific research in the future because of the high measurement accuracy, so studying the accuracy of measuring trees has practical significance for the forestry work. Calculating DBH, tree height and volume by measuring zenith angles, horizontal angles and distance from the center of the instrument to the tree is the principle of measuring standing trees by using total station. Based on the theory of measuring DBH, tree height and volume of standing tree by total station and taking the variance and covariance of measurement factors into consideration, the research deduced the mathematical models to calculate the error of DBH, height and volume of standing tree according to error propagation laws. We chose larches in Beijing as the experimental samples, and analyzed 10 sample groups of different sizes for the difference of relative errors. The results show: 1) There are correlations between the height and the diameter of random tree section, and the value range of correlation coefficient is (0, 0.3); besides, the variance and covariance of these 2 factors affect the error of each segment volume; furthermore, the error of total volume is affected not only by the variance of each section volume, but also by the covariance between 2 adjacent segments’ volumes, and the value range of correlation coefficient is (0.5,0.7); 2) The relative error of DBH, tree height and volume decreases with the increase of the sample size when the different samples are measured by total station. For 10 groups of samples, the relative error of DBH reduces from 0.108% to 0.052%, that of tree height reduces from 0.051% to 0.012% and that of volume reduces from 1.104% to 0.053%. And the average relative error of DBH, tree height and volume is 0.070%, 0.023% and 0.235% respectively. The relative error of DBH and height measurement is less than that of volume when the same sample is measured. The accuracies of DBH are much higher than the DBH measurement standard for national forest resource continuous investigation. The accuracies of tree height and volume of all samples are also much higher than the forest investigation standard for which tree height and volume measurement errors ought to be less than 3%-5%. Volume measurement error is required to be less than 3% for establishing volume tables, so using total station to collect the samples of various specifications can also meet the accuracy of volume tables. In conclusion, total station can satisfy the different needs of forestry survey. [ABSTRACT FROM AUTHOR]

The biomass of Cinnamomum parthenoxylon, a dominant species in karst forest, was studied by the regression estimation method from three aspects of moisture content, biomass spatial-temporal heterogeneity and biomass model fitting to evaluate the biomass of karst forest. The results showed that: (i) The moisture content in leaves and dry wood of Cinnamomum parthenoxylon was obviously higher than that in its other different com ponents, and the moisture content of different components is leaf > dry wood > branch > bark; (ii) The biomass spatial distribution of different components was dry wood > branch > leaf > bark and presents a rising trend with increase of age and DBH ( diameter at breast height). The optimum regression models for biomass of different components of Cinnamomum parthenoxylon were built based on regression analysis of wood biomass. [ABSTRACT FROM AUTHOR]

Glubam is a type of natural bamboo-fiber reinforced polymer composites. This paper focuses on the fundamental mechanical properties of glubam, including its modulus, tensile, compressive, flexural and shear strengths. Because glubam is a new structural material, there is no code or guideline to follow. By referring to relevant timber codes, including GB 1927 ~ 1943--1991 ' Wood physical and mechanical properties test method' and ASTM D143-94 (2007) 'Standard test methods for small clear specimens of timber', considerable number of tests were conducted to obtain the values of modulus, tensile, compressive, bending and shear strengths. The relationships between tensile strength, and modulus and the main fiber orientation were studied. The tests also reveal that cold glued joints between glubam surfaces can weaken the compressive strength. Through the discussion on design methods of glubam structure, the recommended allowable stress values were given based on the Chinese allowable stress design method of timber and favorable design results were found compared with other types of glue laminated timber. [ABSTRACT FROM AUTHOR]

By shaking table tests of two 1 : 2 scaled prototype structures, the seismic performance of Chinese traditional wood building and light wood framed building were studied. The results show that under the horizontal earthquake action whose peak value is less than 0. 5g, the horizontal acceleration responses at the top of columns of Chinese traditional wood building can be less than the acceleration input. The dynamic magnification factor of acceleration ranges from 0.46 to 0. 57. The corresponding displacements can be larger than the displacement input. When the peak value of the input acceleration is bigger than 0. 4g, the obvious slippage between the columns and base-stones, as well as the deflection of joints connecting beams and columns will appear. As the result, the energy of the earthquake can be dissipated and the excellent effect of shock absorption can be achieved. Furthermore, for the light wood framed building, when the peak value of the input acceleration is bigger than 0.4g , the dynamic magnification factor of acceleration can be bigger than 1.0. And if the peak value of input acceleration is not more than 0. 5g , the light wood framed building can remain elastic. [ABSTRACT FROM AUTHOR]