Environmentally friendly, polyacrylic-based polyurethane dispersion (PUD) was synthesised using various molar ratios of polycaprolactone, dimethylolpropionic acid and tetramethyl xylene diisocyanate. Synthesis was car...Environmentally friendly, polyacrylic-based polyurethane dispersion (PUD) was synthesised using various molar ratios of polycaprolactone, dimethylolpropionic acid and tetramethyl xylene diisocyanate. Synthesis was carried out in flowing nitrogen atmosphere. The PUD’s preparations are free of NMP (n-methyl pyrrolidone), a toxic processing solvent generally used during the preparation of PUD’s. The performance of the synthesised polyurethane dispersions with varying NCO/OH molar ratio was tested on wood surface. The physical, chemical, thermal and mechanical properties such as viscosity, particle size, chemical resistance, thermal stability and taber abrasion of applied polyurethane dispersion were carried out as a function of NCO/OH molar ratio. The PUD’s preparation with NCO/OH ratio of 1.4 or 1.6 showed better performance as a wood finish and the results are described in the present study.展开更多
To clarify liquefaction ratios and their construction variations of the main chemical compositions of wood in phenol using phosphoric acid as a catalyst, the chemical ingredients of wood such as holocellulose, cellulo...To clarify liquefaction ratios and their construction variations of the main chemical compositions of wood in phenol using phosphoric acid as a catalyst, the chemical ingredients of wood such as holocellulose, cellulose and lignin, were measured and extracted according to GB methods. With Fourier transform infrared （FTIR）, the product identification of reactant before and after liquefaction in phenol was investigated. The molecular weights and their distributions of the liquefaction results （acetone soluble parts） were studied by gel permeation chromatography （GPC）. Results show that the molecular weights and their distributions of poplar and Chinese fir are almost the same. In poplar, the distribution of cellulose is the largest, and that ofholocellulose the smallest after liquefaction. For Chinese fir, the distribution of holocellulose is the largest, and that of cellulose the smallest. After liquefaction of poplar cellulose, the change bands of FTIR spectrum observed below 1 600 cm^-1, can be attributed to new substitute groups. The same is true for poplar lignin. For Chinese fir, the spectra of liquefaction results of all chemical compositions differ from that of wood meal. This reveals the more activity groups were produced because of the reactions between Chinese fir and phenol. The research shows that the liquefaction ratios of poplar decrease in the following order： holocellulose 〉 lignin 〉 cellulose, and those of Chinese fir in the order： lignin 〉 cellulose 〉 holocellulose.展开更多
In order to find an effective and environmentally friendly method to fix compressive deformation of wood, we determined or measured the recovery ratio, surface hardness, modulus of elasticity （MOE） and the modulus o...In order to find an effective and environmentally friendly method to fix compressive deformation of wood, we determined or measured the recovery ratio, surface hardness, modulus of elasticity （MOE） and the modulus of rupture （MOR） of poplar （Populus cathayana Rehd.） samples pretreated by 40-60% glycerin solutions and then compressed at 160℃ for 10-120 min. We analyzed the data statistically by using two-factor analysis of variance. The chemical compositions of thermal treated wood were also analyzed and compared with untreated control samples. The results showed that the compressive deformation of wood can be properly fixed by glycerin pretreatment. The recovery ratio of compressed wood decreased with prolonging compression time and increasing concent-ration of the glycerin solution. However, the mechanical properties of compressed wood decreased after a long time of compression. The optimal fixation of compressive deformation is to pretreat the wood by a solution of 50% glycerin and compression at 160℃ for 60 min. The analysis of chemical composition showed that glycerin displayed an accelerating effect on degradation of hemicelluloses and lignin during heat-treatment, which explains the main reason of the effect of acceleration of glycerin on deformation fixation of compressed wood.展开更多
A knowledge of the tree-ring stable nitrogen isotope ratio(δ^(15)N)can deepen our understanding of forest ecosystem dynamics by indicating the long-term availability,cycling and sources of nitrogen(N).However,the rad...A knowledge of the tree-ring stable nitrogen isotope ratio(δ^(15)N)can deepen our understanding of forest ecosystem dynamics by indicating the long-term availability,cycling and sources of nitrogen(N).However,the radial mobility of N blurs the interannual variations in the long-term N records.Previous studies of the chemical extraction of tree rings before analysis had produced inconsistent results and it is still unclear whether it is necessary to pre-treat wood samples from specific tree species to remove soluble N compounds before determining theδ^(15)N values.We compared the effects of pre-treatment with organic solvents and hot ultrapure water on the N concentration andδ^(15)N of tree rings from endemic Qinghai spruce(Picea crassifolia)growing in the interior of the central Qilian Mountains,China,during the last 60 a.We assessed the effects of different preparation protocols on the removal of the labile N compounds and investigated the need to pre-treat wood samples before determining theδ^(15)N values of tree rings.Increasing trends of the tree-ring N concentration were consistently observed in both the extracted and unextracted wood samples.The total N removed by extraction with organic solvents was about 17.60%,with a significantly higher amount in the sapwood section(P<0.01).Theδ^(15)N values of tree rings decreased consistently from 1960 to 2019 in both the extracted and unextracted wood samples.Extraction with organic solvents increased theδ^(15)N values markedly by about 5.2‰and reduced the variations in theδ^(15)N series.However,extraction with hot ultrapure water had little effect,with only a slight decrease in theδ^(15)N values of about 0.5‰.Our results showed that the radial pattern in the inter-ring movement of N in Qinghai spruce was not minimized by extraction with either organic solvents or hot ultrapure water.It is unnecessary to conduct hot ultrapure water extraction for the wood samples from Qinghai spruce because of its negligible effect on the removal of the labile N.Theδ^(15)N variation trend of tree rings in the unextracted wood samples was not influenced by the heartwood-sapwood transition zone.We suggest that theδ^(15)N values of the unextracted wood samples of the climate-sensitive Qinghai spruce could be used to explore the ecophysiological dynamics while focusing on the long-term variations.展开更多
Two field experiments were carried out at Akure (7oN, 5o101E) in the rainforest zone of Nigeria in 2006 and 2007 to determine the effectiveness of neem leaf, woodash and modified neem leaf extracts as fertilizer sourc...Two field experiments were carried out at Akure (7oN, 5o101E) in the rainforest zone of Nigeria in 2006 and 2007 to determine the effectiveness of neem leaf, woodash and modified neem leaf extracts as fertilizer sources in improving soil fertility, growth and yield of maize (Zea mays L) and watermelon (Citrulus lanatus) sole and intercrop. There were six treatments namely, poultry manure, neem leaf extract (sole), woodash extract, modified neem leaf (neem leaf + woodash), NPK 15-15-15 and a control (no fertilizer nor extract), replicated three times and arranged in a randomized complete block design (RCB). The extracts (neem leaf, wood ash and modified neem leaf) were applied at 1200 litres per hectare each, NPK 15-15-15 at 300 kg/ha and poultry was applied at 6t/ha. The results showed that there were significant increases (P 2O), K, Ca, Mg, Na, O.M, P and N compared to NPK 15-15-15 and neem leaf extract. For instance, modified neem leaf extract increased soil pH (H2O), K, Ca, Mg, Na, O.M, P and N by 12.4%, 32.8%, 25%, 23.7%, 19.32%, 17.24% and 20% respectively compared to neem leaf extract under intercrop plot. The high soil K/Ca, K/Mg and P/Mg ratios in the NPK 15-15-15 fertilizer treatment led to an imbalance in the supply of P, K, Ca and Mg nutrients to maize and watermelon crops. The least values for growth, yield and soil parameters were recorded under the control treatment. In these experiments, modified neem leaf extract (woodash + neem leaf extracts) applied at 1200 litres/ha was the most effective in improving soil fertility, growth and yield of maize and watermelon (sole and intercrop) and could substitute for 6 tons per hectare of poultry manure and 300kg/ha of NPK 15-15-15 fertilizer.展开更多
Pine wood nematode(PWN), Bursaphelenchus xylophilus, is a serious pathogen of pines throughout the world. Previous work indicated that different concentrations of a-pinene could affect nematode reproduction,however th...Pine wood nematode(PWN), Bursaphelenchus xylophilus, is a serious pathogen of pines throughout the world. Previous work indicated that different concentrations of a-pinene could affect nematode reproduction,however the mechanism of that influence is not clear. In order to examine the reproductive strategies of PWN in response to the stress of the volatile material a-pinene, we investigated different aspects of population changes of B.xylophilus under two concentrations of a-pinene. The results show that a high concentration(214.5 mg ml-1)promoted population growth while a low concentration(56.33 mg ml-1) decreased the population. Population structure was analyzed and it was found that a high concentration of a-pinene decreased the percentage of adults but increased the percentages of larvae and eggs.Furthermore, from the results of an evaluation of sex ratios(female/male), it was determined that a high concentration could elevate sex ratios but a low concentration decreased ratios sharply. These results suggest that the PWN could regulate its population by changing sex ratios under stress of a-pinene. This study has provided a theoretical basis for the prevention and control of pine wilt disease caused by the pine wood nematode.展开更多
This paper focuses on a two-dimensional CFD simulation of a downdraft gasifier and a pilot-scale experiment for verification using wood pellet fuel.The simulation work was carried out via the ANSYS-Fluent CFD software...This paper focuses on a two-dimensional CFD simulation of a downdraft gasifier and a pilot-scale experiment for verification using wood pellet fuel.The simulation work was carried out via the ANSYS-Fluent CFD software package with in-house coding via User Defined Function.Three gasification parameters were taken into account in the simulation and validation to achieve highly accurate results;namely,fuel consumption,temperature profile,and syngas composition.After verification of the developed model,the effects of aspect ratios on temperature and syngas composition were investigated.Results from simulation and experimental work indicated that the fuel consumption rate during the steady state gasification experiment was 1.750±0.048 g/s.The average steady state temperature of the experiment was 1240.32±14.20 K.In sum,the fuel consumption and temperature profile during gasification from modeling and experimentation show an error lower than 1.3%.Concentrations of CO,CO2,H2,and CH4 were 20.42 vol%,15.09 vol%,8.02 vol%,and 2.6 vol%,respectively,which are comparable to those of the experiment:20.00 vol%,15.48 vol%,8.00 vol%,and 2.65 vol%.A high concentration of syngas is observed in the outer radial part of the reactor because of the resistive flow of the air inlet and the synthesis gas produced.The average temperatures during the steady state of the gasifier with aspect ratios(H/D)of 1.00,1.38(experiment),and 1.82 were 978.77±11.60,1256.46±9.90,and 1368.94±9.20 K,respectively.The 1.82 aspect ratio reactor has the smallest diameter,therefore the radiative heat transferred from the reactor wall affects the temperature in the reactor.Syngas compositions are comparable.Inverse relationships between the aspect ratios and the syngas LHV,(4.29–4.49 MJ/N m3),cold gas efficiency(29.66%to 31.00%),and carbon conversion(79.59%to 80.87%)are observed.展开更多
文摘Environmentally friendly, polyacrylic-based polyurethane dispersion (PUD) was synthesised using various molar ratios of polycaprolactone, dimethylolpropionic acid and tetramethyl xylene diisocyanate. Synthesis was carried out in flowing nitrogen atmosphere. The PUD’s preparations are free of NMP (n-methyl pyrrolidone), a toxic processing solvent generally used during the preparation of PUD’s. The performance of the synthesised polyurethane dispersions with varying NCO/OH molar ratio was tested on wood surface. The physical, chemical, thermal and mechanical properties such as viscosity, particle size, chemical resistance, thermal stability and taber abrasion of applied polyurethane dispersion were carried out as a function of NCO/OH molar ratio. The PUD’s preparation with NCO/OH ratio of 1.4 or 1.6 showed better performance as a wood finish and the results are described in the present study.
基金Supported by the Key Research Program Foundation, Ministry of Educational of China (Grant No.02021)the National Natural Science Foundation of China (Grant No. 30471351)
文摘To clarify liquefaction ratios and their construction variations of the main chemical compositions of wood in phenol using phosphoric acid as a catalyst, the chemical ingredients of wood such as holocellulose, cellulose and lignin, were measured and extracted according to GB methods. With Fourier transform infrared （FTIR）, the product identification of reactant before and after liquefaction in phenol was investigated. The molecular weights and their distributions of the liquefaction results （acetone soluble parts） were studied by gel permeation chromatography （GPC）. Results show that the molecular weights and their distributions of poplar and Chinese fir are almost the same. In poplar, the distribution of cellulose is the largest, and that ofholocellulose the smallest after liquefaction. For Chinese fir, the distribution of holocellulose is the largest, and that of cellulose the smallest. After liquefaction of poplar cellulose, the change bands of FTIR spectrum observed below 1 600 cm^-1, can be attributed to new substitute groups. The same is true for poplar lignin. For Chinese fir, the spectra of liquefaction results of all chemical compositions differ from that of wood meal. This reveals the more activity groups were produced because of the reactions between Chinese fir and phenol. The research shows that the liquefaction ratios of poplar decrease in the following order： holocellulose 〉 lignin 〉 cellulose, and those of Chinese fir in the order： lignin 〉 cellulose 〉 holocellulose.
基金supported by the National Natural Science Foundation of China (NSFC) (Grant No.30500386)
文摘In order to find an effective and environmentally friendly method to fix compressive deformation of wood, we determined or measured the recovery ratio, surface hardness, modulus of elasticity （MOE） and the modulus of rupture （MOR） of poplar （Populus cathayana Rehd.） samples pretreated by 40-60% glycerin solutions and then compressed at 160℃ for 10-120 min. We analyzed the data statistically by using two-factor analysis of variance. The chemical compositions of thermal treated wood were also analyzed and compared with untreated control samples. The results showed that the compressive deformation of wood can be properly fixed by glycerin pretreatment. The recovery ratio of compressed wood decreased with prolonging compression time and increasing concent-ration of the glycerin solution. However, the mechanical properties of compressed wood decreased after a long time of compression. The optimal fixation of compressive deformation is to pretreat the wood by a solution of 50% glycerin and compression at 160℃ for 60 min. The analysis of chemical composition showed that glycerin displayed an accelerating effect on degradation of hemicelluloses and lignin during heat-treatment, which explains the main reason of the effect of acceleration of glycerin on deformation fixation of compressed wood.
基金supported by the National Natural Science Foundation of China (41971104)the Open Foundation of the State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment+1 种基金Chinese Academy of Sciences (CASSKLLQG1817)the Qilian Mountain National Park Research Center (Qinghai)(GKQ2019-01)。
文摘A knowledge of the tree-ring stable nitrogen isotope ratio(δ^(15)N)can deepen our understanding of forest ecosystem dynamics by indicating the long-term availability,cycling and sources of nitrogen(N).However,the radial mobility of N blurs the interannual variations in the long-term N records.Previous studies of the chemical extraction of tree rings before analysis had produced inconsistent results and it is still unclear whether it is necessary to pre-treat wood samples from specific tree species to remove soluble N compounds before determining theδ^(15)N values.We compared the effects of pre-treatment with organic solvents and hot ultrapure water on the N concentration andδ^(15)N of tree rings from endemic Qinghai spruce(Picea crassifolia)growing in the interior of the central Qilian Mountains,China,during the last 60 a.We assessed the effects of different preparation protocols on the removal of the labile N compounds and investigated the need to pre-treat wood samples before determining theδ^(15)N values of tree rings.Increasing trends of the tree-ring N concentration were consistently observed in both the extracted and unextracted wood samples.The total N removed by extraction with organic solvents was about 17.60%,with a significantly higher amount in the sapwood section(P<0.01).Theδ^(15)N values of tree rings decreased consistently from 1960 to 2019 in both the extracted and unextracted wood samples.Extraction with organic solvents increased theδ^(15)N values markedly by about 5.2‰and reduced the variations in theδ^(15)N series.However,extraction with hot ultrapure water had little effect,with only a slight decrease in theδ^(15)N values of about 0.5‰.Our results showed that the radial pattern in the inter-ring movement of N in Qinghai spruce was not minimized by extraction with either organic solvents or hot ultrapure water.It is unnecessary to conduct hot ultrapure water extraction for the wood samples from Qinghai spruce because of its negligible effect on the removal of the labile N.Theδ^(15)N variation trend of tree rings in the unextracted wood samples was not influenced by the heartwood-sapwood transition zone.We suggest that theδ^(15)N values of the unextracted wood samples of the climate-sensitive Qinghai spruce could be used to explore the ecophysiological dynamics while focusing on the long-term variations.
文摘Two field experiments were carried out at Akure (7oN, 5o101E) in the rainforest zone of Nigeria in 2006 and 2007 to determine the effectiveness of neem leaf, woodash and modified neem leaf extracts as fertilizer sources in improving soil fertility, growth and yield of maize (Zea mays L) and watermelon (Citrulus lanatus) sole and intercrop. There were six treatments namely, poultry manure, neem leaf extract (sole), woodash extract, modified neem leaf (neem leaf + woodash), NPK 15-15-15 and a control (no fertilizer nor extract), replicated three times and arranged in a randomized complete block design (RCB). The extracts (neem leaf, wood ash and modified neem leaf) were applied at 1200 litres per hectare each, NPK 15-15-15 at 300 kg/ha and poultry was applied at 6t/ha. The results showed that there were significant increases (P 2O), K, Ca, Mg, Na, O.M, P and N compared to NPK 15-15-15 and neem leaf extract. For instance, modified neem leaf extract increased soil pH (H2O), K, Ca, Mg, Na, O.M, P and N by 12.4%, 32.8%, 25%, 23.7%, 19.32%, 17.24% and 20% respectively compared to neem leaf extract under intercrop plot. The high soil K/Ca, K/Mg and P/Mg ratios in the NPK 15-15-15 fertilizer treatment led to an imbalance in the supply of P, K, Ca and Mg nutrients to maize and watermelon crops. The least values for growth, yield and soil parameters were recorded under the control treatment. In these experiments, modified neem leaf extract (woodash + neem leaf extracts) applied at 1200 litres/ha was the most effective in improving soil fertility, growth and yield of maize and watermelon (sole and intercrop) and could substitute for 6 tons per hectare of poultry manure and 300kg/ha of NPK 15-15-15 fertilizer.
基金financially supported by Fundamental Research Funds of Research Institute of Forest New Technology,CAF(CAFYBB2018SY037)National Key Research and Development Program(2016YFC1200604)。
文摘Pine wood nematode(PWN), Bursaphelenchus xylophilus, is a serious pathogen of pines throughout the world. Previous work indicated that different concentrations of a-pinene could affect nematode reproduction,however the mechanism of that influence is not clear. In order to examine the reproductive strategies of PWN in response to the stress of the volatile material a-pinene, we investigated different aspects of population changes of B.xylophilus under two concentrations of a-pinene. The results show that a high concentration(214.5 mg ml-1)promoted population growth while a low concentration(56.33 mg ml-1) decreased the population. Population structure was analyzed and it was found that a high concentration of a-pinene decreased the percentage of adults but increased the percentages of larvae and eggs.Furthermore, from the results of an evaluation of sex ratios(female/male), it was determined that a high concentration could elevate sex ratios but a low concentration decreased ratios sharply. These results suggest that the PWN could regulate its population by changing sex ratios under stress of a-pinene. This study has provided a theoretical basis for the prevention and control of pine wilt disease caused by the pine wood nematode.
文摘This paper focuses on a two-dimensional CFD simulation of a downdraft gasifier and a pilot-scale experiment for verification using wood pellet fuel.The simulation work was carried out via the ANSYS-Fluent CFD software package with in-house coding via User Defined Function.Three gasification parameters were taken into account in the simulation and validation to achieve highly accurate results;namely,fuel consumption,temperature profile,and syngas composition.After verification of the developed model,the effects of aspect ratios on temperature and syngas composition were investigated.Results from simulation and experimental work indicated that the fuel consumption rate during the steady state gasification experiment was 1.750±0.048 g/s.The average steady state temperature of the experiment was 1240.32±14.20 K.In sum,the fuel consumption and temperature profile during gasification from modeling and experimentation show an error lower than 1.3%.Concentrations of CO,CO2,H2,and CH4 were 20.42 vol%,15.09 vol%,8.02 vol%,and 2.6 vol%,respectively,which are comparable to those of the experiment:20.00 vol%,15.48 vol%,8.00 vol%,and 2.65 vol%.A high concentration of syngas is observed in the outer radial part of the reactor because of the resistive flow of the air inlet and the synthesis gas produced.The average temperatures during the steady state of the gasifier with aspect ratios(H/D)of 1.00,1.38(experiment),and 1.82 were 978.77±11.60,1256.46±9.90,and 1368.94±9.20 K,respectively.The 1.82 aspect ratio reactor has the smallest diameter,therefore the radiative heat transferred from the reactor wall affects the temperature in the reactor.Syngas compositions are comparable.Inverse relationships between the aspect ratios and the syngas LHV,(4.29–4.49 MJ/N m3),cold gas efficiency(29.66%to 31.00%),and carbon conversion(79.59%to 80.87%)are observed.
