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1.
Cycling of soluble non-protein N compounds is thought to be indicative of the N-nutritional status of trees. We determined the major N forms in bark, wood and foliage and estimated the dependence of prevalent N forms on N availability in Pinus sylvestris L. trees from northern Sweden. Trees subjected to severe N limitation and trees that had been fertilized with an average 64 kg N ha(-1) year(-1) for 25 years were analyzed. Bark and wood samples were collected by tangentially cryo-sectioning the trunk into 30-microm thick sections, from the bark to the functional xylem. Soluble amino compounds were extracted from the sections for analysis. Sap samples from twigs were obtained by centrifugation, and bark samples from twigs were obtained by tissue extraction. In both needles and bark, arginine dominated the amino-N pool. Because arginine concentrations in needles increased with N fertilization, arginine dominance of the amino-N pool in needles was higher in N-fertilized trees than in control trees. In bark, N fertilization resulted in a large increase in glutamine concentration, so that glutamine accounted for a larger proportion of the amino-N pool in bark in N-fertilized trees than in control trees. Glutamine dominated the amino-N pool in wood of control trees. Nitrogen fertilization resulted in an increased proportion of arginine in the wood amino-N pool. We conclude that the composition of the amino-N pools in bark, wood and foliage is highly sensitive to N supply. The composition of the amino-N pools can contribute to the regulation of tree N-nutritional status, which is mediated by shoot to root signalling by long-distance transport of amino compounds. 相似文献
2.
Tatsuro Ohira Yuusuke Edashige Naoyuki Matsui Mitsuyoshi Yatagai 《Journal of Wood Science》2011,57(3):226-233
Hiba (Thujopsis dolabrata) wood was treated with supercritical carbon dioxide (scCO2) at stepwise temperature increments from 50° to 400°C continuously so that extractives (dichloromethane-soluble and -insoluble
phases) and solid residues were obtained. The yield of extractives from hiba wood increased with increasing extraction temperature.
The volatile compounds in the dichloromethane-soluble phase from scCO2 extraction at 50°C contained only terpenoids. However, the volatile compounds in the dichloromethane-soluble phase from scCO2 extraction at 300°C not only contained terpenoids but also phenols, furans, hydrocarbons, and organic acids. The yield of
β-thujaplicin, which is a useful compound in hiba wood, increased with increasing extraction temperature from 50°C to 300°C;
the optimal conditions for extracting β-thujaplicin were 300°C and 19.61 MPa. Further study of degradated compounds from the cellulosic and lignic materials of hiba
wood after stepwise high-temperature scCO2 treatment above 300°C may provide clues to its efficient use. 相似文献
3.
Summary Based on the fact that bark is an almost perfect water barrier and assuming that bark is impregnated with materials which aid in rendering it impermeable to water, the hydrophobic and water-repellent properties of several bark extractives were investigated. Products obtained after extraction with polar and non-polar solvents showed widely different properties. Some were extremely hydrophobic and water-repellent with a water-solid-air contact angle higher than 100°. These were the products obtained from extraction with benzene and mineral turpentine. Alcohol and acetone extractives had contact angles as low as 23° but coatings from some of these materials nevertheless had a high efficiency as water barriers. The efficiency of the various extractives as water repellents or water barriers was determined by coating wood with 10 per cent solutions of the extractives in different solvents and determining the extent to which water could be prevented from being absorbed and causing swelling of the wood and thereby reduce the dimensional changes of the wood. The extractives obtained with nonpolar solvents were extremely efficient as true water repellents while the polar aleohol extracts were far better than could be expected from their almost hydrophilic properties. Nature has therefore provided for hydrophilic film-formers combined with hydrophobic materials which act as a double line of defence against water absorption. The hydrophilic extractives, in addition, act as a bridging agent between the strongly hydrophobic extractives and the hydrophilic cell wall material.Since some of the extractives from wattle bark have excellent hydrophobic properties, and since this bark is available in large quantities as a waste product after tannins have been extracted, the utilization of certain wattle bark extractives as water repellents could be economically attractive. 相似文献
4.
Constituents of tars formed during the aging of bamboo (Phyllostachys pubescens), oak (Quercus serrata), and pine (Pinus densiflora) wood crude vinegars were analyzed by pyrolysis-gas chromatography (Py-GC) and pyrolysis-gas chromatography-mass spectrometry
(Py-GC-MS) to investigate their origination. The pyrolysate of tars obtained from the wood and bamboo crude vinegars were
almost identical and were primarily composed of phenolic compounds and aromatic hydrocarbons. In addition, during the aging
of model wood vinegar that was prepared for comparison with the wood and bamboo vinegars, a marked decrease was observed in
the levels of phenolic compounds (phenol; o-, p-, and m-cresol; and syringol). Furthermore, the Py-GC-MS results of the tars produced during the aging of the model wood vinegar
revealed that phenolic compounds were primarily responsible for the formation of tar during the aging of wood and bamboo crude
vinegars. Pyrroles, which may be derived from the primary pyrolysate of amino acids, nitrogen-containing extracts, or both,
were also partially involved in the formation of tar during the aging period. 相似文献
5.
油茶饼粕是油茶种子制备茶油后的副产物,含有多种生物活性成分。为给油茶饼粕资源的高效利用提供理论依据,采用索氏抽提方法,以乙醇为浸提溶剂,对冷冻干燥除水后的油茶饼粕进行浸提,对其提取物和提取残渣进行真空浓缩干燥处理,并在600℃的条件下分别进行热裂解,然后对热裂解产物的组分进行热裂解-气质联用(Py-GC/MS)分析。结果表明:油茶饼粕乙醇提取物的热裂解组分中含有杂环类、酮、酯、酚、烃类、醛等成分,而其提取残渣的热裂解组分中含有杂环类、酮、酸、酯、醚、酚、糖类、氨基酸、腈等成分;油茶饼粕乙醇提取物与提取残渣的热裂解产物中的部分组分可用作生物医药、香料、化妆品的生产原料。 相似文献
6.
7.
António M. Jordão Jorge M. Ricardo-da-Silva Olga Laureano An Adams Jan Demyttenaere Roland Verhé Norbert De Kimpe 《Journal of Wood Science》2006,52(6):514-521
The purpose of this study was to investigate the sorption of selected volatile substances from oak wood-chip samples (Quercus pyrenaica Willd. and Quercus petraea L.) subjected to different toasting levels, namely, without toasting, with medium toasting, and with strong toasting, through
the use of solid-phase microextraction (SPME). The main volatile compounds identified as a function of the toasting level
and botanical species were furfural, hexanal, α-pinene, d-limonene, decanal, vitispirane, ethyl hexanoate, cis-3-methyl-γ-octalactone (“oak lactone” or “whisky lactone”), α-terpineol, p-xylene, and nonanal. Considering the data obtained from the toasted woods (medium and strong intensity) in comparison with
those of nontoasted woods, it can be pointed out that the average peak area and the number of compounds identified in the
gas chromatogram decreased during the toasting process. In general, regarding the compounds analyzed, quantitative differences
were found between the two oak wood species under study. High values of volatile compounds were found in Quercus pyrenaica oak wood chips. In addition, for the number of compounds identified in oak wood extracts and directly extracted from solid
oak wood chips by SPME, it is concluded that the best extraction process for volatile compounds from oak wood is the use of
oak wood-chip liquid extracts. 相似文献
8.
The thermal decomposition of wood wastes obtained from jack pine has been studied in both oxidising and inert atmospheres using thermogravimetric techniques supported by gaseous and residue product analysis. The effects of selected sequences of chemical additives on the reaction rate parameters of both native and extracted bark samples have also been examined. The maximum rate of wood waste pyrolysis is believed to be related to the rapid decomposition of the cellulose constituent, which occurs at around 350°C in nitrogen. In air, this value is shifted to around 300°C and may be explained by the intervention of exothermic reactions involving other wood constituents present in the complex wood matrix. The trend shown in the analytical results for the various wood waste residues was similar to that established by previous workers for the pyrolysis of coalification products on the basis of H/C and O/C ratios which proceed towards the carbonisation and oxidation poles, respectively, for residues obtained from heating in inert and oxidising atmospheres. Isothermal weight-change data were found to fit model kinetic expressions which indicate that the pyrolysis process may be transport-controlled.We are pleased to acknowledge the award of support funds (C.F.) from the Ontario Ministry of the Environment. 相似文献
9.
After enzymic hydrolysis of polysaccharides in milled wood or pulp the unhydrolysed lignin residue becomes soluble in certain polar solvents. Extensive disintegration of the wood is necessary to obtain a sufficient accessibility toward the enzyme. For milling a porcelain rotary ball mill is recommended. A relationship has been found between the milling energy, which is proportional to the size of the mill, the milling time, and the yield of ball-milled wood lignin (BMWL). Enzymatically isolated lignin (EIL) requires a critical milling time which is shorter than that for obtaining maximum yields of BMWL. A procedure for isolation of the total lignin content from wood and pulps in the form of three fractions has been developed, giving a water soluble, low molecular carbohydrate-lignin complex by water extraction of ball-milled wood, a BMWL-carbohydrate complex by subsequent extraction with dioxane, and a EIL-carbohydrate complex by dioxane extraction of the residue after enzymic hydrolysis. 相似文献
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11.
Bruno D. Mattos Tainise V. Lourençon Luis Serrano Jalel Labidi 《Wood material science & engineering》2016,11(4):209-216
This study aims to evaluate the chemical composition of wood and extractives of Pinus taeda and Schizolobium parahyba (guapuruvu) as potential feedstock for new applications in the biorefinery industry. For this purpose, their content of α-cellulose, hemicellulose, insoluble lignin, hot water solubility, NaOH1% solubility, inorganic materials (ash), and monomeric sugars by high-performance liquid chromatography was quantified. Attenuated total reflectance infrared spectroscopy and thermogravimetric analysis were also used to complete the physicochemical characterization of the studied woods. The extractives were obtained by soxhlet extraction with ethanol:toluene and dichloromethane and identified with pyrolysis-gas chromatography/mass spectroscopy technique. The results showed that guapuruvu wood has the higher amount of hemicellulose (16%) when compared to pine wood (10%), which resulted in higher solubility in alkali solution. Furthermore, in relation to other biomasses, the two woods presented more percentage of lignin and minor content of hemicelluloses. The P. taeda wood presented the highest percentage of extractives mainly composed of fatty acids and aromatic hydrocarbons, while guapuruvu wood had a higher percentage of phenolic compounds and also fatty acids. Both the materials have low content of extractives with dichloromethane and were mainly composed of lipophilic compounds. 相似文献
12.
Mirko De Rosso Davide Cancian Annarita Panighel Antonio Dalla Vedova Riccardo Flamini 《Wood Science and Technology》2009,43(5-6):375-385
Aging wine and spirits in wooden barrels is an industrial process used to stabilize color and improve limpidity; many compounds are released from the wood and enrich the sensorial characteristics of the product. The main wood species used for making barrels is oak, but in particular cases also acacia, chestnut, cherry and mulberry. In this work, polyphenols contained in the extracts of these wood species obtained by solutions of 50% hydroalcohol as well as a model wine were studied and compared with the extracts from oak. The hydroalcoholic extracts of chestnut and mulberry had higher total polyphenols, followed by cherry, acacia and oak, respectively. The oak model wine extract had the highest percentage of polyphenols extractable by the wine, followed by chestnut, acacia, cherry and mulberry, respectively. Chestnut extracts had the highest percentage of oxidizable compounds, followed by acacia, oak, mulberry and cherry. The GC/MS–EI profile of 50% hydroalcoholic extracts revealed as principal volatiles several benzene compounds containing a guaiacol residue, and high contents of C6–C18 fatty acids. To our knowledge, this is the first study reporting on polyphenolic and complete volatile compounds characterization of these woods for oenological purposes. 相似文献
13.
木材高效利用的重要途径除了实木高效利用之外,还有劣材优用、小材大用,前者如定向/华夫刨花板,后者如小径材制材、制造胶合板和LVL、生产胶合木等,都是国际上为人们所重视的相关技术。对于剩余物的利用,也同样以提高原料利用效率和生产高效率为前提来提高剩余物利用的比例量。我国木材加工技术多数源于国外,对于技术的引进、消化和吸收问题需格外引起注意并应进行深入研究,尤其要研究的是“如何引进国外技术”的先进方法,以本国的研究和开发结果为基础,在对其中内涵进行深入了解的同时开展技术引进、消化和吸收。 相似文献
14.
《Forest Ecology and Management》2005,209(3):207-224
An electronic aroma detection (EAD) technology known as conductive polymer analysis (CPA) was evaluated as a means of identifying and discriminating woody samples of angiosperms and gymnosperms using an analytical instrument (electronic nose) that characterizes the aroma profiles of volatiles released from excised wood into sampled headspace. The instrument measures electrical-resistance changes generated by adsorption of volatiles to the surface of electroactive, polymer-coated sensors. Unique digital electronic fingerprints of wood aromas, derived from multisensor-responses to distinct mixtures of wood volatiles, were obtained from woods of individual tree species. A reference library containing aroma signature patterns for 23 tree species was constructed for identifications of unknown samples using pattern-recognition algorithms. The 32-sensor array used with an Aromascan A32S instrument was sensitive to a wide diversity of organic compounds and produced outputs of distinct electronic aroma signature patterns in response to wood volatiles that effectively identified unknown samples from individual tree species included in the reference library. Some potential applications of CPA methods for research in ecology, forestry, plant taxonomy, and related disciplines were identified with some significant advantages and limitations. Other applications of this technology were discovered for the management of forested stands and ecosystems based on the identification of roles that wood-inhabiting organisms play in stand dynamics and long-term ecosystem functions. Results pertaining to tree systematics and phylogeny are discussed in the context of prevailing opinions of oak taxonomy. 相似文献
15.
杉木粉液化与液化产物树脂化的研究 总被引：2，自引：0，他引：2
以硫酸为催化剂、苯酚为液化剂采用溶剂热法对杉木粉进行液化,用杉木粉液化产物制备出酚醛树脂;考察了反应温度、反应时间、液比(苯酚-木粉的质量比)和催化剂用量对杉木粉液化效率的影响,并初步探讨了液化产物残渣率对所制酚醛树脂性能的影响。实验结果表明,杉木粉液化的最佳工艺条件是:反应温度160℃,液化时间12 h,液比值3,催化剂用量3%,在此条件下残渣率约为10%。液化产物残渣率的测定表明,升高反应温度、延长反应时间、增加液比和催化剂用量可以降低残渣率,提高液化效率;液比值为0.5~1.5时残渣率随液比增加而显著降低,催化剂用量为0.5%~2%时液化效率的变化明显。红外光谱结果表明,由液化产物所合成的酚醛树脂中羟甲基含量较高。液化产物残渣率低时制备的酚醛树脂残碳率较高。 相似文献
16.
木材是自然界中分布最广泛的材料之一,在制造业和建筑业等领域有着广泛的应用。我国是木材消费和木材加工剩余物产出大国,但目前国内木材加工剩余物利用率较低、利用方式单一,与发达国家相比差距较大。通过创新木材剩余物处理方式,研发相关技术,可逐步缩小与发达国家之间的差距。黏结剂喷射（3DP）技术具有材料来源广泛、加工简单、成型效率高等特点,基于木质材料特点,以木材加工剩余物为原料,实现木质材料增材制造具有广阔的发展前景。文中以增材制造中的木质纤维及其分类为背景,介绍增材制造中木质耗材的研究现状,重点阐述木质材料3DP中典型黏结剂喷射成型（BJ）技术、散装材料选择性沉积技术和单层制造（ILF）技术等3类技术的成型原理、研究进展及其最新应用等,根据木质材料的物理特性和成型机理,探讨黏结剂、粉末床工艺和后处理等因素对木质材料3DP成型精度和成型质量的影响,并对木质材料3DP技术存在的问题进行分析并展望其发展趋势。 相似文献
17.
《Wood material science & engineering》2013,8(1):45-53
Abstract Samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected for moisture sorption and swelling tests at 25°C. These tests evaluated the fiber saturation point (FSP) by two methods: following adsorption over distilled water, and from the volumetric swelling intersection point. Cold-water and hot-water extractives, sequential cyclohexane, acetone and methanol extracts, ash content, wood density and interlocked grain were also determined on matched samples. The results indicated that adsorption tests over distilled water were not applicable for determining FSP in all wood species. Condensation of water vapor apparently occurred, even though temperature during adsorption was controlled to the nearest 0.01°C. The volumetric swelling intersection point method was judged more appropriate. FSP ranged from 15 to 25% for tropical hardwoods and was 30% for sugar maple wood. FSP was negatively correlated with wood density, acetone extracted fraction, interlocked grain and ash content. These parameters each exerted similar effects on variability in FSP. 相似文献
18.
《Wood material science & engineering》2007,2(1):45-53
Samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected for moisture sorption and swelling tests at 25°C. These tests evaluated the fiber saturation point (FSP) by two methods: following adsorption over distilled water, and from the volumetric swelling intersection point. Cold-water and hot-water extractives, sequential cyclohexane, acetone and methanol extracts, ash content, wood density and interlocked grain were also determined on matched samples. The results indicated that adsorption tests over distilled water were not applicable for determining FSP in all wood species. Condensation of water vapor apparently occurred, even though temperature during adsorption was controlled to the nearest 0.01°C. The volumetric swelling intersection point method was judged more appropriate. FSP ranged from 15 to 25% for tropical hardwoods and was 30% for sugar maple wood. FSP was negatively correlated with wood density, acetone extracted fraction, interlocked grain and ash content. These parameters each exerted similar effects on variability in FSP. 相似文献
19.
Roger E. Hernández 《Wood Science and Technology》2007,41(3):249-265
Wood samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected to perform moisture sorption
tests associated with parallel-to-grain and tangential compression tests using a multiple step procedure at 25°C. Cold-water
and hot-water extractives, sequential cyclohexane (CYC), acetone (ACE) and methanol (MET) extracts, ash content (ASH), wood
density and interlocked grain (IG) were evaluated on matched samples too. Wood density corrected for the accessory substances
was by far the major factor positively affecting the compressive properties of tropical hardwoods. The total amount of accessory
substances is required in order to establish better relationships between physico–mechanical properties and density of tropical
hardwoods. For a given wood density, the ultimate stress in parallel-to-grain compression was higher in tropical hardwoods
than in temperate hardwoods. However, the compliance coefficients for both types of woods were quite similar. Sequential extraction
with organic solvents was the most suitable method for evaluating the effect of extractives on compressive properties of tropical
hardwoods. The CYC and ACE fractions did not contribute to variation in these mechanical properties. The substances dissolved
in MET affected positively the compliance coefficient s
11 in parallel-to-grain compression and negatively the compliance coefficient s
33 in tangential compression. The IG decreased the compliance coefficient s
11 but also decreased the ultimate stress in parallel-to-grain compression. Finally, variations in compressive properties that
were due to changes in equilibrium moisture content (EMC) were clearly influenced by wood density; denser woods were more
sensitive to changes in EMC than lighter woods. 相似文献