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1.
The improvement of wood surface wettability can clearly improve bonding properties, as well as enhance physical and mechanical properties of wood composites. In our investigation, the microwave plasma (MWP) technique was adopted to treat the surface of common teak. The treatment effect was evaluated by measuring the contact angles of liquids and calculating the free surface energy. The results show that the modification effect improved when the sample was located 120 mm from the resonance cavity, rather than at 80 mm. A MWP treatment over a short span of time is useful to lower the contact angles and improve the surface wettability considerably. The range of decreasing contact angles, tested by water, could reach 74% at a distance of 120 mm. __________ Translated from Journal of Northeast Forestry University, 2007, 35(12): 31–33 [译自: 东北林业大学学报]  相似文献   

2.
Bamboo fiber dissolution and hydrolysis in formic acid were studied. After hydrolysis, formic acid can be recovered in a clean state and reused. Solid water-soluble sugars were obtained. After being dipped into the formic acid solution for 30 min, the bamboo fibers started to swell. After one hour, the bamboo fibers gradually started to dissolve in the formic acid solution. The color of the liquor/solution turned green and dark. In the end, the bamboo fibers became thoroughly dissolved in the liquor after four hours. There was a clear hierarchical tissue structure on the fiber surface, as observed by AFM before treatment. The differential structure disappeared after 30 min of treatment. The fiber surface became plump and glossy. After six hours reaction at 60°C, the solid sugar mixture recovered contained glucose, cellobiose, cellotriose, cellotetrose, cellopentose and cellohexaose. A significant fraction of the sugar products consisted of monomeric glucose. More than 54.5% of the bamboo fiber mass had been transformed into monomeric glucose. __________ Translated from Biomass Chemical Engineering, 2007, 41(2): 5–10 [译自: 生物质化学工程]  相似文献   

3.
Dynamic properties of bamboo, Phyllostachys pubescens, with moisture content (MC) ranging from −130 to 130°C, were studied by dynamic mechanical analysis (DMA). The results showed that the hygrothermal effect on dynamic mechanical properties was negative. The storage modulus decreases with increasing temperature and MC, and glass transition temperature decreases with increasing MC. The glass transition temperature and tan delta of bamboo were 30.5°C, 0.02 and 10.61°C, 0.04, when MC was 10% and 34%, respectively. __________ Translated from Journal of Nanjing Forestry University (Natural Sciences Edition), 2006, 30(1): 65–68 [译自: 南京林业大学学报(自然科学版), 2006, 30(1): 65–68]  相似文献   

4.
In this study, the contact angles of four different reference liquids (including distilled water, diiodomethane, formadide and glycerol) formed on the surfaces of wood, treated with chromated copper arsenate (CCA) and two other emerging copper-based water-borne systems (commercial names: NW and NS) were measured with sessile drop method. Based on the contact angle data, the surface energy was obtained from the acid-base approach. The total surface energy consisted of Lifshiz-van der Waals parameter and acid-base parameter. Results showed that the NW and CCA treatments made the wood surface more hydrophobic while the NS treatment had the reverse effect on the wood surface mainly owing to the increased penetration of earlywood. By using three liquids, diiodomethane, formamide and distilled water, the total surface energy obtained for untreated earlywood, untreated latewood, CCA-treated earlywood, CCA-treated latewood, NW-treated earlywood, NW-treated latewood, NS-treated earlywood and NS-treated latewood were 43.1, 44.5, 43.4, 45.1, 49.4, 40.6, 46.0 and 40.9 mJ/m2, respectively. The surface energy of CCA-treated wood was almost the same as untreated wood. After NW and NS treatments, the surface energy of both earlywood and latewood changed a little. However, the change was not so obvious as to draw any further conclusion concerning the influence of NW and NS treatments on the surface energy of wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(4): 1–4 [译自: 北京林业大学学报]  相似文献   

5.
This study investigated the liquefaction of bamboo in phenol, which involved the effects of weight ratios of phenol to bamboo, amount of catalyst, temperature, etc. The study showed that liquefaction could be accomplished with a phenol to bamboo weight ratio of 2–1: 1, a 5% catalyst of HCl or BF3, and a temperature of 115°C. Liquefied bamboo formaldehyde (BLF) resin adhesive for exterior use could be obtained with a phenol to formaldehyde molar ratio of 1:1.6–2.0. The curing behavior of BLF resin adhesive, studied by TG-DSC and IR analyses, showed that BLF resin adhesives had a lower curing temperature than PF adhesives but had the same characteristic trough in IR spectra as PF adhesives. __________ Translated from Chemistry and Industry of Forest Products, 2004, 24(3) [译自: 林产化学与工业, 2004, 24(3)]  相似文献   

6.
We used heart rate variability (HRV), an electrophysiological index, to investigate the changes of the sympathetic and parasympathetic nervous systems of people when they were in contact with wood and other materials, in a time-domain, a frequency-domain, and by means of nonlinear dynamics. Our aim was to discover the relations among thermal parameters of different kinds of material, human physiological feedbacks, and psychological perceptions. It shows that the activity of the sympathetic nervous system when in contact with wood increased no more than when in contact with metal and ceramic materials, while the activity of the parasympathetic nervous system weakened less than when in contact with these materials. The time taken by the sympathetic and parasympathetic nervous systems to revert to their normal state after contact with cloth and wood was shorter than that after contact with metal and ceramic. A subjective survey, by SD method, showed that the tactility of wood was favorable and people preferred wood to other kinds of material. Correlation analysis’ results showed that there was a close correlation among the HRV indices, human psychological emotion ratings, and thermal parameters of the different kinds of materials. The experiment proves that the effect of wood on our autonomous nervous system is slightly better than that of other materials except for cloth. Wood does not damage people’s health. __________ Translated from Journal of Northeast Forestry University, 2005, 33(2): 29–31 [译自: 东北林业大学学报, 2005, 33(2): 29–31]  相似文献   

7.
The technology of liquefying processed-waste bamboo with phenol is investigated by single factor trials and an orthogonal design. We studied the preparation technology and properties of adhesives from this phenol-liquefied bamboo with formaldehyde (BPF). The results show that temperature has a significant effect on liquefaction. The effect of the mass ratio of phenol to bamboo comes second and the catalyst dosage within the range of 2%–4% is the least effective. The optimum conditions of liquefaction are as follows: a mass ratio of phenol to bamboo 3.5, a catalyst dosage of 4%, liquefying temperature 145°C and liquefying time 60 min. The liquefaction rate of bamboo reached 99.1%. For the preparation of the adhesive, a mass ratio of liquefied bamboo products to formaldehyde (37%) is 100 to 164.8–199.5, while the ratio 100 to 108.2 is the best. This adhesive has a lower curing temperature than that of normal PF resin. At a hot-press temperature of 130 or 140°C, this new adhesive provides excellent bonding strength of plywood. The most favorable temperature for hot-pressing is 140°C. __________ Translated from Chemistry and Industry of Forest Products, 2007, 27(6): 65–70 [译自: 林产化学与工业]  相似文献   

8.
The collection of information on bamboo forests plays a crucial role in the calculation of carbon content reserves, and the acquisition of high-precision information will be good for reducing estimation errors. High precision is obtained with the adoption of a back propagation (BP) neural network to extract information on bamboo forests from Enhanced Thematic Mapper + (ETM +) remote sensing images with the assistance of neural network modules provided by Matlab. We obtained a production precision of 84.04% and a user precision of 98.75%. We also conducted a comparison of classification differences of three training functions, i.e., the, Levenberg-Marquardt BP algorithm function (Trainlm), a gradient decreasing function of adaptive learning rate BP (Traingda), and a gradient lowering momentum BP algorithm function (Traingdm). Our analysis suggests that Traingda had the highest precision while Trainlm function required the shortest training time. __________ Translated from Journal of Zhejiang Forestry College, 2008, 25(4): 417–421 [译自: 浙江林学院学报]  相似文献   

9.
The growth process of natural poplar-birch forests   总被引：1，自引：0，他引：1  
With a combination of permanent and temporary sample plots, we investigated the growth conditions of natural poplar-birch forests. The forests were divided into four site classes, using statistical and analytical techniques in a quantitative model, in descending order where site class I was the best. On this basis, the growth of natural poplar-birch forests in the different site classes was studied. The growth processes of height and diameter at breast height were divided into three stages: a fast growing period, a stable growing period and a slow growing period. Results of this study provide a theoretical basis for the directive cultivation of natural poplar-birch forests. __________ Translated from Journal of Northwest Forestry University, 2005, 33(5): 9–12 [译自: 东北林业大学学报, 2005, 33(5): 9–12]  相似文献   

10.
In order to identify the potential of sulfur (S) content in the rings of Masson pine (Pinus massoniana) in the Pearl River Delta as a bio-indicator of regional history of atmospheric pollution, dendrochemistry was used to determine the temporal distribution of S content in the xylem of Masson pines from Zhaoqing Dinghushan and Nanhai Xiqiaoshan, Guangdong Province, southern China. The results indicated that contents of xylem S increased temporally and peaked in the rings formed in the most recent years at both sites. In the rings formed during the same period before the 1980s, S contents were not significantly different between the two sites, while in the rings formed at the same period after the 1980s, S content at Xiqiaoshan were significantly higher than those at Dinghushan. The chronosequences of the S indices at both sites could be easily marked as three periods: before 1970, during 1971–1985, and during 1986–2002. Based on the temporal changes of the xylem S contents and certain social-economic indices after the 1980s in the Delta, the history of atmospheric pollution at the study sites could be reconstructed as follows: 1) before 1970, a period in which the air was relatively clear, 2) 1971–1985, a period in which the air was gradually polluted, and 3) 1986–2002, a period in which the air was most severely polluted in the Delta. __________ Translated from Journal of Beijing Forestry University, 2008, 30(2): 1–7 [译自: 北京林业大学学报]  相似文献   

11.
The regeneration of exhausted solutions of electroless nickel plating wood veneer was realized using soluble calcium salt to precipitate and remove phosphite and then using fluoride to remove residual calcium ions from the solution. The effect of the pH value of the solution, treatment temperature and the molar ratio of calcium ions to phosphite ions on the removal efficiency of phosphite was investigated. Wood veneer was electroless plated using regenerated solutions. A coating with better electrical conductivity and electromagnetic shielding was obtained. __________ Translated from Journal of Northeast Forestry University, 2005, 33(3): 47–48 [译自: 东北林业大学学报, 2005, 33(3): 47–48]  相似文献   

12.
This research investigated the variation in tensile properties and the relationship between the tensile properties and the air-dried density for the moso bamboo (Phyllostachys pubescens) by sampling at different heights and radial positions. Results showed that the variation of the longitudinal tensile properties in the radial direction was greater than that in the longitudinal direction. The longitudinal tensile modules of elasticity (MOE) ranged from 8.49 to 32.49 GPa. MOE for the outermost layer was 3–4 times as high as that for the innermost layer. The longitudinal tensile strength (MOR) ranged from 115.94 to 328.15 MPa. MOR for the outermost layer is 2–3 times as high as that for the innermost layer. Linear and curvilinear regressions were done from tested data of MOE, MOR and air-dried density in this paper. The linear equation worked a little better than the curvilinear one to predict the longitudinal MOR and MOE from air-dried density. __________ Translated from Scientia Silvae Sinicae, 2006, 42(3): 72–76 [译自: 林业科学]  相似文献   

13.
The poor adhesion of bamboo coatings is a serious issue in the bamboo industry. To develop a pretreatment method that improves the adhesion of films and increases the economic value of bamboo products, a study of hydrogen peroxide treatment with solutions of various pH (pH 4–9) on bamboo surfaces was conducted. Five-year-old ma bamboo (Dendrocalamus latiflorus Munro), and nitrocellulose lacquer were used in the study. Surface properties of the bamboo such as contact angle and color were evaluated, and 180° peel strength and shear strength tests for measuring adhesion of films were conducted. The results showed that the wettability of water droplets and the carbonyl group concentration on the bamboo surface were increased significantly by alkaline (pH 8 and 9) hydrogen peroxide treatments. There was only minor color variation and the outer wax layer of bamboo was etched to form additional recesses after hydrogen peroxide treatment. It was also found that all hydrogen peroxide treatments improved the adhesion of bamboo coating; bamboo treated with hydrogen peroxide at pH 7 showed the greatest improvement. The enhanced adhesion was attributed to the mechanical interlocking of the film on the treated bamboo rather than to surface activation.  相似文献   

14.
In order to analyze the effect of temperature gradient on moisture movement during highly intensive drying, such as microwave-vacuum drying, the profile of the temperature and moisture content in sealed wood whose opposite faces were subjected to temperature gradient for a short time was measured. The ratio of the moisture content (MC) gradient to the temperature gradient (dM/dT) was calculated and the factors influencing moisture movement under nonisothermal conditions were discussed. The results indicate that moisture moved in wood from the warm surface to the cold one even if opposite faces of the sealed wood assembly were exposed continuously to different but constant temperatures for a short period. The moisture content on the cold surface was higher than that on the warm surface. The moisture content gradient opposite to the temperature gradient was established, and the dM/dT was below 0.9%/°C. The temperature in the sample and the distance from the hot surface of the sample was strongly linearly correlated. With an increase in temperature, initial moisture content and experimental time, the dM/dT was significantly increased. __________ Translated from Journal of Beijing Forestry University, 2005, 27(2): 96–100 [译自: 北京林业大学学报, 2005, 27(2): 96–100]  相似文献   

15.
Calculating aggregation index by the sample-plot data used to lead to computing error due to the existence of a boundary effect. Here, we suggest a method for adjusting boundary effect in the analysis of spatial patterns at different stages of development of the broad-leaved Korean pine forest. This method is good for the reasonable management and biological control of the forests. The total station was used to sample the relative coordinates data at four corners of the temporary sample plot and of each tree in the field. Based on the sampling data, a correct approach to the boundary effect on aggregation index was put forward to the spatial pattern analysis of the broad-leaved Korean pine forest in its different stages of development. The results showed that the forest trees grew in a clumped pattern in the stage dominated by the pioneer trees, and that the trees were distributed in a random pattern in the stage dominated by the companion trees or in the mature stage. The spatial pattern of the broad-leaved Korean pine forest changing from clumped to random distribution is influenced by biological characteristic, the adaptive strategy of tree species and the natural disturbance in its entire development. __________ Translated from Journal of Nanjing Forestry University, 2005, 29(3): 57–60 [译自: 南京林业大学学报, 2005, 29(3): 57–60]  相似文献   

16.
Differentiating from normal wood, pit membranes in wetwood of subalpine fir contain bacteria of water drop shape or orbicular shape, and flaky shape, as observed using Scanning Electronic Microscope. Not only are ray parenchyma cells in wetwood partially degraded but also margo strands in pit membranes are somewhat degraded by bacterial activities. Most of the bordered-pit membranes in normal wood are unaspirated in green conditions and the proportions of aspirated pits in earlywood and latewood account for only 6.8% and 13.4%, respectively. Nevertheless, most of the bordered-pit membranes in wetwood are aspirated in green conditions and the proportions of aspirated pits account for 77.7% and 72.1%, respectively. The problem of hard-to-dry for subalpine fir could be reasoned from the considerable amount of aspirated pit membranes in wetwood. __________ Translated from Journal of Nanjing Forestry University (National Science Edition), 2006, 30(1): 53–56 [译自: 南京林业大学学报 (自然科学版), 2006, 30(1): 53–56]  相似文献   

17.
Chinese pine caterpillar (Dendrolimus tabulaeformis) larvae were fed with pine needles of different degrees of damage to evaluate the effects of pine needles on the growth and development of larvae. The results showed that the nutritional index of the larvae declines after feeding on the damaged pine needlings. The lowest amount of food ingested and voided feces, the lowest nutritional index, slowest development, lightest pupae and most mortality were found in those pine caterpillar larvae fed with pine needles which were 50% damaged. The damaged pine needles significantly affected the population dynamics of Chinese pine caterpillars. The nutritional indices of larvae fed with 25% and 75% damaged pine needles were similar. The nutritional index of the dark morphs was higher than that of the tinted morphs, however, their mortality was lower than that of the tinted morphs. This phenomenon was reversed at the later stage of development when the larvae were fed on 50% damaged pine needles. __________ Translated from Journal of Beijing Forestry University, 2005, 27(6): 83–88 [译自: 北京林业大学学报, 2005, 27(6): 83–88]  相似文献   

18.
Using quantification theory I, an analysis of the relation of soil water and qualitative factors, such as, slope degree, slope aspect, slope position, and soil in Wangjiagou watershed area has been done. The study aims to quantify the factors influencing soil water, the descending order of the factors being the slope aspect, soil, slope degree, and slope position, thereby scientifically facilitating division of afforestation site types and afforestation site products digitally on geographical information system (GIS). __________ Translated from Journal of Northwest Forestry University, 2006, 21(3): 184–188 [译自: 西北林学院学报, 2006, 21(3): 184–188]  相似文献   

19.
The sap flow of the sampled Populus euphratica stems at different radial depths and directions had been studied in Ejina Oasis, in the lower reaches of the Heihe River. Based on sap flow measurements, the transpiration of the entire canopy was calculated. Results showed a linear correlation between the sap flow and the sapwood area of the P. euphratica. Through the analysis of the diameter at breast height in the sample plot, it was found that the distribution of the diameters and the corresponding sapwood area was exponentially correlated, with the coefficient of correlation being 0.976,7. The calculated transpiration of the Populus euphratica canopy was 214.9 mm based on the specific conductivity method. Translated from Scientia Silvae Sinicae, 2006, 42(7): 28–32 [译自: 林业科学]  相似文献   

20.
Timber import is an important and integral part of China’s timber trade. According to different kinds of product type, this paper analyzes its import in 2004 separately; based on the conditions of China’s timber import trade in 2004, this paper finds out some existing problems and puts forward corresponding countermeasures. __________ Translated from Journal of Beijing Forestry University (Social Sciences Edition), 2006, 5,(1) [译自: 北京林业大学学报(社会科学版), 2006, 5 (1)]  相似文献   

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