共查询到20条相似文献,搜索用时 15 毫秒
1.
The effect of aging on lignins of wood 总被引:1,自引:0,他引:1
Summary Samples of different wood species varying in age from 900 to 4400 years and stored during this period under different conditions were analyzed for their lignin content. Lignins isolated from the samples were investigated by IR-spectroscopy. It could be shown that lignin in wood undergoes oxidative changes which lead to a decrease in the amount of lignin isolated by the hydrochloric acid procedure. at Hamburg-Lohbrügge.DAAD Visiting Professor Fellowship to study and do research at the Bundesforschungsanstalt für Forst- und Holzwirtschaft at Hamburg-Lohbrügge.Dedicated to Karl Kratzl on the occasion of his 60th anniversary 相似文献
2.
Structural studies on the chemical bonds between lignins and carbohydrates in spruce wood 总被引:7,自引:0,他引:7
Summary A lignin-carbohydrate material from black spruce (Picea mariana) was treated with a hemicellulase mixture. The carbohydrates in the remaining material were studied by the following methods. a) Treatment with 0.1 M NaOH in the presence of sodium borohydride followed by selective hydrolysis of the furanosidic bonds, b) Smith degradation (periodate oxidation followed by mild acid hydrolysis). The results obtained indicate that lignin is bound to all types of sugar units in the hemicelluloses. For arabino-4-O-methylglucuronoxylan, linkages to the side-chain units seem to dominate. The links to the 4-O-methylglucuronic acid units are ester bonds, probably benzyl ester bonds. Those to the other sugar units in the hemicelluloses are ether bonds, probably benzyl ether bonds. The results suggest, furthermore, that fractions of cellulose are linked to lignin.The authors are indebted to Dr. H. H. Brownell, Ottawa, Canada, for a gift of extracted black spruce wood meal, and to Professor Bengt Lindberg, Stockholm, Sweden, for the use of glc equipment in his laboratory 相似文献
3.
Daniel Yeboah Andrew J. Burton Andrew J. Storer Emmanuel Opuni-Frimpong 《New Forests》2014,45(1):35-52
Most research on carbon content of trees has focused on temperate species, with less information existing for tropical trees and very little for tropical plantations. This study investigated factors affecting the carbon content of nineteen tropical plantation tree species of ages seven to twelve and compared carbon content of Khaya species from two ecozones in Ghana. For all sample trees, volume of the main stem, wood density, wood carbon (C) concentration and C content were determined. Estimated stem volume for the 12-year-old trees varied widely among species, from 0.01 to 1.04 m3, with main stem C content ranging from 3 to 205 kg. Wood density among species varied from 0.27 to 0.76 g cm?3, with faster growing species exhibiting lower density. Significant differences in wood density also occurred with position along the main stem. Carbon concentration also differed among tree species, ranging from 458 to 498 g kg?1. Differences among species in main stem C content largely reflected differences among species in estimated main stem volume, with values modified somewhat by wood density and C concentration. The use of species-specific wood density values was more important for ensuring accurate conversion of estimated stem volumes to C content than was the use of species-specific C concentrations. Significant differences in wood density did exist between Khaya species from the wet and moist semi-deciduous ecozones, suggesting climatic and site factors may also need to be considered. Wood densities for these plantation grown trees were lower than literature values reported for the same species in natural forests, suggesting that the application of data derived from natural forests could result in overestimation of the biomass and C content of trees of the same species grown in plantations. 相似文献
4.
Patrick Rousset Catherine Lapierre Brigitte Pollet Waldir Quirino Patrick Perre 《Annals of Forest Science》2009,66(1):110-110
5.
Variation in density and moisture content of wood and bark among twenty Eucalyptus grandis progenies
Summary Variation in density and moisture content of Eucalyptus grandis wood and bark is described utilizing the trees established for a half-sib progeny test in southern Florida. Differences in density and moisture content among progenies were significant. Variations in wood properties were largely due to the genetic differences. No relationship was found between wood density and wood moisture content. Implications for genetic manipulation of wood quality for this species were discussed. 相似文献
6.
Residual wood meal after extraction of milled wood lignin (WMEM) ofEucalyptus globulus was extracted with alkali and LiCl/N,N-Dimethylacetamide (DMAc). These agents dissolve mainly hemicellulose and cellulose, respectively. The extractability of WMEM in alkali solutions was influenced by the degree of swelling of the cellulose. Under good swelling conditions, considerable amounts of cellulose and lignin were extracted with the hemicellulose. Maximum extractability was about 60% of the WMEM under optimum conditions (3 M or 5 M LiOH or 3M NaOH solution). Some portion of cellulose was extracted with LiCl/DMAc at room temperature. Thus, lignin inE. globulus WMEM was divided into three fractions: hemicellulose-lignin fraction, cellulose-lignin fraction, and insoluble-lignin fraction.Part of this work was presented at the 49th annual meeting of the Japan Wood Research Society, Tokyo, April 1999; and at the 50th annual meeting of the Japan Wood Research Society, Kyoto, April 2000 相似文献
7.
Summary Thermogravimetry-mass-spectrometry (TGMS) as a sophisticated analytical instrument is described for the thermal analysis of milled wood lignins from spruce (Picea abies L.), beech (Fagus sylvatica L.) and bamboo (Bambus sp.). The samples were heated on the thermobalance in an inert gas atmosphere (Ar) with 20°C/min heating rate. The weight loss curves (TG) and their 1st derivatives (DTG) were recorded. The evolution of 10 low mass degradation products with m/z below 44 was monitored as a function of the temperature by means of a quadrupol mass spectrometer. Thus the intensity profiles of H2, CH3
, H2O, CO, CHO, HCHO, CH3O, CH3OH, CH3CO and CO2 were recorded and interpreted in terms of lignin structure and the course of carbonization. The results are in agreement with the results of differencial scanning calorimetry (DSC) and pyrolysis-gas-chromatography mass-spectrometry (PyGCMS) of the phenolics. 相似文献
8.
Summary The development and localization of phenolic compounds in sapwood and heartwood of Abies alba Mill. have been studied using cytological and UV-microspectrophotometric methods. The synthesis of phenolic substances was apparently initiated in vesicles developing from rough ER of the ray parenchyma cells in sapwood. They are different from the phenolic material in the pit membrane and cell wall of heartwood. There was no indication to suggest that the polyphenols in the cell wall of heartwood were either derived from or identical with the phenolic substances in the lumina of ray cells.Dedicated to Prof. Dr. H. von Pechmann on the occasion of his 70th birthdayWe are thankful to Professor Dr. Walter Liese for his support and to Mrs. R. Schultze and Miss R. Endeward for technical assistance. 相似文献
9.
10.
Andrei Prida Alexis Ducousso Rémy J. Petit Gérard Nepveu Jean-Louis Puech 《Annals of Forest Science》2007,64(3):313-320
The effect of species and ecological conditions on oak volatile extractive content was investigated in an evenaged (100 years) stand located in western France. The sample included a total of 286 trees (118 sessile, 158 pedunculate and 10 oaks with an intermediate morphology) growing in contrasted environments (plateau, intermediate slope, small valley). The main factor influencing oak extractives level is species. The effect of the local environment appears negligible. No correlation between ring width and volatile extractive content was found. Q. petraea is significantly richer than Q. robur in eugenol and whisky-lactone (10.8 vs. 0.6 μg/g). However, two groups of sessile oaks could be identified, one poor and one rich in whisky-lactone. Among the latter, either the cis or the trans stereoisomer was predominant, suggesting that their production is not independent. A strong spatial structure was detected for whisky-lactone (cis-, trans- and total whisky-lactone, for the two species combined but also for Q. petraea alone in the case of the cis isomer). 相似文献
11.
12.
The chemical composition and structural characterization of the milled wood lignin (MWL) and successively alkali-fractionated lignins from bamboo (Phyllostachys incarnata Wen) were comparatively investigated using Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), 2D heteronuclear single quantum coherence (HSQC), and alkaline nitrobenzene oxidation. It was found that bamboo MWL (S/G?~?1.3) is of SGH type with a considerable amount of esterified p-coumaric acid and etherified ferulic acid. Molecular weights of 3,320?g/mol for MWL and varying weights between 970 and 3,430?g/mol for the alkali-fractionated lignins were obtained. Moreover, 2D HSQC of MWL showed a predominance of β-O-4′ linkages (65%), followed by β–β′ linkages (15%) and lower amounts of β-5′ (7%), β-1′ (4%), 5–5′ (4%) linkages, and cinnamyl acetate end groups (5%). In addition, a percentage (~45%) of the lignin side chain was found to be acylated at the γ-carbon. However, the alkali-fractionated lignins lost parts of these linkages during successive alkaline fractionation processes. 相似文献
13.
Summary Periodate oxidation, because of its high selectivity in degrading phenolic nuclei, has been combined with nitrobenzene oxidation and phenyl nucleus exchange techniques to investigate the nature of wood lignin in situ. For both softwood and hardwood, the phenolic and etherified components of wood lignin have been shown to differ significantly in chemical composition, and the etherified lignin structure appears to be substantially more condensed.Financial support from the Empire State Paper Research Associate (ESPRA) and by the NRICGP of USDA (No. 93-37103-9318) is greatly appreciated 相似文献
14.
Guo Mnghui 《林业研究》1996,7(2):56-59
In this paper, the variation pattern of wood properties was studied for naturalCunninghamia lanceolata. The mathematical models of property parameters were obtained on tracheid length, microfibril angle, late wood percentage,
growth ring width and growth ring density in the radial direction. The interrelation were analyzed between tracheid length
and microfibril angle. The result can provide scientific theory basis for wood utilization and early prediction of wood properties. 相似文献
15.
以102个17年生杉木无性系为试材,对木材的干缩性与吸水性进行测定分析发现,木材干缩性、吸水性在杉木无性系间差异极显著;干缩性变异幅度为3.1%~20.0%,表型变异系数达59.8%;吸水性变异幅度在214.5%~338.1%间,表型变异系数为13.2%。木材干缩性与吸水性均具有明显的无性系方差分量,表明杉木木材干缩性与吸水性受遗传控制。进一步研究显示,杉木无性系木材干缩性遗传变异系数为38.6%,重复力为0.390,均属中低水平;吸水性遗传变异系数值虽较低,但重复力相对较高(0.664),属中上水平;在不同入选率(10%、20%、30%)下,木材干缩性与吸水性随入选率的降低其遗传增益值(绝对值)不断提高。研究还发现,杉木木材干缩性与木材基本密度、心材比间为极显著遗传负相关,与木材吸水性间则表现为极显著遗传正相关;木材吸水性在遗传水平上与胸径、材积、心材比间呈极显著正相关,而与木材基本密度间为极显著负相关。 相似文献
16.
Influence of wood moisture content and wood temperature on fungal decay in the field: observations in different micro-climates 总被引:1,自引:0,他引:1
In this study, Scots pine sapwood (Pinus sylvestris L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco) specimens were exposed in double layer field trials at four different exposure sites and under different exposure
conditions (in total ten test sets). The material climate of wood in terms of wood moisture content (MC) and wood temperature
was automatically monitored over a period of 6 years and compared with the progress of decay. The aim of this study was to
highlight the interrelationship between microclimate, material climate, and decay as a basis for the establishment of dose-response
functions to be used for service life prediction of wood and wood-based products. Differences in resulting decay dynamics
between the test sites as well as between the different types of exposure were quantified and discussed with respect to corresponding
microclimatic and material climatic conditions. The time between the beginning of exposure and the first occurrence of visible
decay varied between the sites and influenced the total decay development. The fundamental importance of direct decay factors,
such as MC and wood temperature, were underlined and basic requirements for establishing dose-response-functions to be used
in service life prediction models were derived. 相似文献
17.
Variation of cell length in bark and wood of tropical trees 总被引:2,自引:0,他引:2
Summary The variation in length of cell elements both in bark and wood of a few tropical trees (Mangifera altissima, Mansonia altissima, Pentacme contorta, Pterocarpus marsupium, Shorea megrosensis, Shorea squamata, Triplochtion scleroxylon) is described. The phloem fibres and sieve tube members show a tendency for increase in length from periderm to cambium, just as the wood fibres and vessel members increase from pith to cambium. The phloem fibres are generally longer than wood fibres (40–70%). In woods with storeyed cambia the sieve tube members exhibit no variation, retaining a constant length throughout the width of the bark; the phloem fibres possess the normal trend of a length increase from periderm to cambium. The length variation of sieve tube members and phloem fibres with the height of the tree generally exhibits a decreasing trend from butt to top, although a slight increase in length of phloem fibres at the top was noticed.Presented at the IUFRO Division V Meeting, September 1973, Cape Town, South AfricaThanks are due to Mrs. K. Puchstein for help with the measurements. The financial support by the Deutsche Forschungsgemeinschaft and the Gesellschaft der Freunde und Förderer der Bundesforschungsanstalt für Forst- und Holzwirtschaft, Reinbek, is also gratefully acknowledged. 相似文献
18.
Alpo Ranta-Maunus 《Wood Science and Technology》1975,9(3):189-205
Wood is regarded as a viscoelastic material. Creep deformations that arise from variations in the moisture content are described by a theory of hydroviscoelasticity developed by the author. Two different types of behaviour have been apparent: one, arising from a continuously increasing strain with periodic variation in the moisture content, and another with no cumulative effect. The theory has been applied to previously published experimental results concerned with beech, pine, hoop pine, klinki pine, along with birch and spruce plywood. Birch and spruce plywood have been used for experiments concerned with periodically-cycling bending moment and moisture content. The results obtained have been compared with the theory presented. Glue-laminated beams have been subjected to long-term outdoor loading extending for five years. A brief discussion is given of the results obtained. 相似文献
19.
The resin content in larch wood is usually determined by the traditionalBenzene-Alcohol Extract Method(BAEM).In order to meet the requirement of production prac-tice,the authors present two simple quick determination methods,IR lamp method and hydrogenperoxide solution method.Compared with the results of traditional method,the results of newmethods are nearly the same as former,therefore,both two methods can reflect the change condi-tion of resin content in wood. 相似文献
20.
Changes in moisture content of sugi (Cryptomeria japonica D. Don) wood during high-temperature saturated and superheated steam treatments were investigated. A system for in situ weighing of specimens was used, and the reduction of wood substance by heating was taken into consideration. At 160°C the loss of wood substance due to heating was significant and influenced the moisture content values, but it was almost negligible at 120°C. Treatment time and temperature affected the moisture content in saturated steam but not in superheated steam. Excess water in a saturated closed system appears to promote the decomposition of wood and condensation in or on specimens.Parts of this work was presented at the 49th, 50th, and 52nd Annual Meetings of the Japan Wood Research Society in Tokyo, April 1999; Kyoto, April 2000; and Gifu, April 2002 相似文献