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Reaction behavior of milled wood lignin in an ionic liquid, 1-ethyl-3-methylimidazolium chloride

Reaction behavior of milled wood lignin in an ionic liquid, 1-ethyl-3-methylimidazolium chloride

Abstract We investigated the reaction behavior of milled wood lignin (MWL) obtained from Japanese cedar (Cryp- tomeria japonica) and Japanese beech (Fagus crenata) in an ionic liquid, 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]). This solvent can liquefy wood. The sample was treated with [C2mim][Cl] at 120 °C using an oil bath or microwave irradiation. MWL easily dissolved in [C2mim][Cl]. Although solubilized, MWL was slightly depolymerized and it retained its high molecular weight after 96 h of treatment. Only small amounts of low molecular weight compounds such as vanillin, coniferyl- aldehyde, syringaldehyde and sinapylaldehyde were pro- duced. As the treatment time was extended the chlorine from [C2mim][Cl] reacted with the MWL. These results indicate that MWL is stable in [C2mim][Cl] although limited depolymerization and modification by [C2mim][Cl] occurred.
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Chemical structural elucidation of total lignins in woods I: fractionation of the lignin in residual wood meal after extraction of milled wood lignin

Chemical structural elucidation of total lignins in woods I: fractionation of the lignin in residual wood meal after extraction of milled wood lignin

It seems likely that residual cellulose in the IL fraction is part of the lignin-carbohydrate complexJ 2-~4 When the WMEM was first extracted with LiC1/DMAc and subsequently e[r]

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An Investigation of the Milled Wood Lignin Isolation Procedure by Solution- and Solid-State NMR Spectroscopy.

An Investigation of the Milled Wood Lignin Isolation Procedure by Solution- and Solid-State NMR Spectroscopy.

Table 8.1 gives the data from the modified DFRC analysis for the Vibratory MWL, Vibratory (Dry) MWL, and Rotary Porcelain 6 Week MWL. As indicated by the Unit A composition, each of the MWL preparations are enriched in phenolic end group material with a subsequent decrease in etherified β-O-4’ substructures (Unit C). This is expected as the MWLs are isolated by depolymerization involving homolytic cleavage of the β-aryl ether bonds in the wood meal. There was a slight increase in the Unit B content of the Vibratory (Dry) MWL, however this will not be addressed by quantitative 13 C NMR due to peak overlap it is difficult to differentiate an α-aryl ether bond. Previous results by HMQC have not detected these interunit linkages (Sections 5 and 6), consistent with literature values. [158] It is therefore questionable as to whether these structures exist.
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Elucidation of the Structure of Cellulolytic Enzyme Lignin from Loblolly Pine (pinus taeda)

Elucidation of the Structure of Cellulolytic Enzyme Lignin from Loblolly Pine (pinus taeda)

however its structure and biosynthesis pathway have not yet to be completely elucidated (Ralph et al., 2004; Boerjan et al., 2003). A primary problem in the elucidation of the structure of native lignin is that it cannot be isolated in a chemically unaltered form. The first major advance towards isolating lignin in a relatively unaltered state was made by Björkman (Björkman, 1954), extracting lignin from finely ball-milled wood with aqueous dioxane. The resulting milled wood lignin (MWL) is considered to be a representative source of native lignin and has been extensively used in the elucidation of native lignin structure. However, concerns exist over the similarity between MWL and native lignin based on the low yields (25-50% of protolignin) and structural alteration due to ball milling. Ball milling reduces the degree of polymerization, creating new free-phenolic hydroxyl groups through cleavage of β- aryl ether linkages as well as increasing α-carbonyl groups via side-chain oxidation (Lai et al., 1971; Chang et al., 1975; Ikeda et al., 2002; Fujimoto et al., 2005; Gellerstedt et al., 1989). Recently, Ikeda et al. investigated the effects of several balling-milling methods on the cleavage of β-aryl ether linkages in MWL using a modified DFRC (Derivatization Followed by Reductive Cleavage) method in combination with nitrobenzene oxidation (Ikeda et al., 2002). It was found that the phenolic β-O-4’ structures increased continuously at the expense of the etherified β-O-4’ structures during ball-milling. Based on the increase in α- aryl ether groups, it was suggested that some condensation reactions may occur during the ball milling process, especially if the ball-milling is conducted in a vibratory ball mill without toluene (dry ball-milling). Ball milling primarily affects the side-chain structure of the C 9 phenyl-propane units in lignin (Ikeda et al., 2002; Fujimoto et al., 2004).
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On the formation of diphenylmethane structures in lignin under Kraft, soda and EMCC pulping conditions

On the formation of diphenylmethane structures in lignin under Kraft, soda and EMCC pulping conditions

In our earlier work the phosphorus NMR spectra of solubilized kraft lignin contained, among others, a signal centred around 143.5 ppm (40). On the basis of model compound work and calculations based on the Hammett principles (50), this signal was tentatively assigned to diarylmethane structures possess- ing free phenolic hydroxyl groups (40). In an effort to confirm the validity of our earlier work, the interaction of milled wood lignin with formaldehyde under kraft pulping conditions was clarified by conducting experiments in which different amounts of formaldehyde were introduced into the reaction mixture prior to the cook. More specifically, two different sets of experiments were carried out with four samples of milled wood lignins being subjected to kraft pulping at 120°C with the addition of formaldehyde accounting for 50 and 100% of the total aryl ether units of lignin, respectively (51). After quanti- tative recovery of the lignin, the 31 P NMR spectra were re-
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Genomics and biochemistry investigation on the metabolic pathway of milled wood and alkali lignin-derived aromatic metabolites of Comamonas serinivorans SP-35

Genomics and biochemistry investigation on the metabolic pathway of milled wood and alkali lignin-derived aromatic metabolites of Comamonas serinivorans SP-35

MWL: milled wood lignin; AL: alkali lignin; H: ρ‑hydroxyphenyl; G: guaia‑ cyl; S: syringyl; LiP: lignin peroxidases; MnP: manganese peroxidases; VP: versatile peroxidases; DyPs: dye decolorizing peroxidases; Lacc: laccases; β‑KAP: β‑ketoadipate pathway; LB: Luria broth; LM: lignin medium; COD: chemical oxygen demand; SEM: scanning electron microscopy; FTIR: Fourier‑transform infrared spectrometer; GC–MS: gas chromatography–mass spectrometry; BSTFA: N, O‑bis (trimethylsilyl) trifluoroacetamide; TMCS: trimethylchlorosilane; TMS: trimethylsilyl; SMRT: single molecule real time; HCA: 4‑hydroxycinnamic acid; 2,4‑DHB: 2,4‑dihydroxybenzaldehyde; HAP: 4′‑hydroxyacetophenone; DHPG: 3,4‑dihydroxyphenylglycol; HBA: 4‑hydroxy‑ benzoic acid; DOMA: 3,4‑dihydroxymandelic acid; 3‑MP: 3‑methylphenol; BHT: butylated hydroxytoluene; GSTs: glutathione transferases; NAD‑ADH: NAD‑dependent alcohol dehydrogenase; GGE: guaiacylglycerol‑β‑guaiacyl ether; MPHPV: α‑(2‑methoxyphenoxy)‑β‑hydroxypropiovanillone; GS‑HPV: generateβ‑glutathionyl‑γ‑hydroxypropiovanillone; GSSG: glutathione disulfide; HPV: γ‑hydroxypropiovanillone; VVA: vanilloyl acetic acid; PA: phenylacetic acid; HBAld: 4‑hydroxybenzaldehyde; SA: syringaldehyde; catA: catechol 1, 2‑dioxygenase; catB: muconate cycloisomerase; catC: muconolactone D‑isomerase; pcaD: β‑ketoadipate enol‑lactone hydrolase; pcaI: 3‑oxoadipate CoA‑transferase subunit A; pcaJ: 3‑oxoadipate CoA‑transferase subunit B; pcaF: β‑ketoadipyl CoA thiolase; pcaC: carboxymuconolactone decarboxylase; pcaHG: protocatechuate 3, 4‑dioxygenase; pcaB: β‑carboxymuconate cycloi‑ somerase; pcaR: β‑KAP transcription regulator; DHCDC: cis‑1, 2‑dihydroxy‑ cyclohexa‑3, 5‑diene‑1‑carboxylate; BadR: benzoate anaerobic degradation regulator; PA‑CoA: phenylacetyl‑CoA; ep‑CoA: 1, 2‑epoxyphenylacetyl‑CoA; DHAP: 2, 4′‑dihydroxyacetophenone; HBA‑CoA: 4‑hydroxybenzoyl‑CoA; ALDH: aldehyde dehydrogenase; HPA: 4‑hydroxyphenylacetate; HAPMO: 4‑hydroxy‑ acetophenone monooxygenase; HPCA: 3,4‑dihydroxyphenylacetate; ADH: alcohol dehydrogenase; MHPG: 3‑methoxy‑4‑hydroxyphenylglycol; COMT: catechol O-methyltransferase; MOPEGAL: 3‑methoxy‑4‑hydroxyphenylglycola‑ ldehyde; VMA: 3‑methoxy‑4‑hydroxymandelate; 3MGA: 3‑O‑methylgallate; V/ SODM: vanillate/syringate O‑demethylase.
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New strategy to elucidate the positive effects of extractable lignin on enzymatic hydrolysis by quartz crystal microbalance with dissipation

New strategy to elucidate the positive effects of extractable lignin on enzymatic hydrolysis by quartz crystal microbalance with dissipation

Extensive efforts have been devoted to investigate the negative effects of lignin on enzymatic hydrolysis, and how to relieve its inhibition. However, the positive effects of lignin on enzymatic hydrolysis have also been reported upon recently [21, 28]. Lignosulfonate has been observed to form lignosulfonate–cellulase complexes, which are believed to enhance electrostatic repulsion between the enzyme and residual bulk lignin. This interaction was shown to improve enzymatic hydrolysis of lignocellulose [21, 29]. Our own previous work observed that lignin obtained from ethanol organosolv-pretreated sweetgum (“EL”) surprisingly showed a positive effect on enzymatic hydrolysis [28]. However, the underlying mechanism for the positive effects of EL was not fully investigated. In an attempt to reveal the potential mechanism, both EL and the residual bulk lignin were sequentially fraction- ated from ethanol organosolv-pretreated mixed wood sawdust. EL was simply isolated from the pretreated sub- strates by ethanol extraction due to its favorable ethanol solubility. Milled wood lignin (“MWL”) was then iso- lated from the ethanol extracted residues to represent the residual bulk lignin to serve as a representative iso- late of the residual lignin [24]. Both isolated lignin frac- tions’ chemical structures were elucidated by nuclear magnetic resonance (NMR) analysis. In addition, enzyme adsorption on these two lignin fractions was monitored by QCM-D analysis in real time. Furthermore, the effects of the assembly between EL and MWL on the enzyme adsorption were revealed by QCM-D analysis. The results herein will aid in developing a stronger collective understanding of the positive and negative effects exerted by lignin upon enzymatic hydrolysis.
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Structure of small lignin fragments retained in water-soluble polysaccharides extracted from birch MWL isolation residue

Structure of small lignin fragments retained in water-soluble polysaccharides extracted from birch MWL isolation residue

Abstract To analyze the structural features of lignin in the vicinity of lignin–carbohydrate linkages, water-soluble lignin–carbohydrate complex (LCC) with low lignin content was prepared from residual birch wood meal after the ex- traction of milled wood lignin (MWL). The molecular weight distribution of lignin in this LCC appeared together with carbohydrate in the relatively high molecular weight region of the gel permeation chromatogram. This result was consistent with our previous results obtained for the same fraction of Japanese cedar (sugi); however, after treatment with polysaccharide-degrading enzyme, the molecular weight distribution of carbohydrate and that of lignin shifted significantly to the lower region. These results dem- onstrated that molecular size of this LCC is determined by carbohydrates while lignin is present as a minor fragment in this fraction. The syringyl/guaiacyl (S/V) ratio of this LCC was higher than other lignin fractions. Ozonation analysis implied that this LCC has a relatively high number of β -1 structures. It is likely that lignin that exists near lignin– carbohydrate linkages has more endwise-type features than other lignin fractions.
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Moisture Adsorption Rate and Effective Diffusivity in Chinese Milled Rice

Moisture Adsorption Rate and Effective Diffusivity in Chinese Milled Rice

Abstract. Four varieties of Chinese milled rice samples with 11.90–15.56% initial moisture content (IMC, wet basis) were used to determine the rate of moisture adsorption using the gravimetric method at 10, 20, 25, 30, and 35°C under 65%, 86%, and 100% relative humidity (RH), respectively. A moisture diffusion equation was modified to fit the relationship between the moisture ratio (MR) of samples and exposure time. In the range of 65% to 100% RH, the lower IMC of milled rice samples corresponded to higher moisture adsorption rate at temperatures of 10 to 35°C. The moisture adsorption rate of samples increased with an increasing temperature. The moisture sorption rate of samples with the same IMC increased with increasing RH at certain temperatures. A single milled rice kernel was geometrically considered a finite homogeneous cylinder shape, and the analytical solution of the partial differential equation of moisture diffusion was given. The effective moisture diffusivity was calculated using a slope method by plotting the experimental data in terms of ln (MR) versus rewetting time. In the range of 10–35°C, the effective moisture adsorption diffusivity of milled rice kernels with normal moisture was 4.321×10 -9 –1.117×10 -7 m 2 h -1 . For the same IMC, the effective moisture diffusivity of milled kernels tended to increase with increases in surrounding temperature at certain relative humidity levels, but decreased with an increase in RH at certain temperatures. It was concluded that the milled rice samples from different types had similar effective moisture diffusivity when similar IMC was given.
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Relating Breast-Height Wood Properties to Whole-Stem Wood Properties in Loblolly Pine

Relating Breast-Height Wood Properties to Whole-Stem Wood Properties in Loblolly Pine

Others such as Muneri and MacDonald (1998), used disk, core, and Pilodyn sampling techniques to measure correlated results predicting whole-tree densities for Eucalyptus globulus and E. nitens. One of their objectives was to determine which method of sampling was the most efficient and accurate for predicting whole-tree wood traits. The five methods they compared were: 1.) taking a single pilodyn reading; 2.) taking pilodyn readings from four sides of the tree (north, south, east and west); 3.) removing a single core sample; 4.) removing a single disk sample; and 5.) taking several disks at 10, 30, 50, and 70% of total tree height. The average means, standard deviations, and variances were calculated for each method and coefficients of variation were calculated for each trait. The two species were divided into 5 and 10 year age classes and were sampled from three different sites. They found disk samples to be the most accurate, explaining 95% of the variation and correlations. Pilodyn samples explained little of the variation (26 to 27%), while cores explained 81 to 82% of the variation. Also, Muneri and Macdonald found that depending on the species, different sampling heights would more accurately predict whole-tree wood density. A follow up study by Raymond and Muneri (2001), found core samples explained 84 to 89% of
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In situ measurement of tensile elastic moduli of individual component polymers with a 3D assembly mode in wood cell walls

In situ measurement of tensile elastic moduli of individual component polymers with a 3D assembly mode in wood cell walls

Several studies concerning the elastic properties of isolated wood polymers have been reported. For instance, the elastic longitudinal modulus of cellulose I purified from ramie has been reported as 134 GPa [12, 13]. Cousins [14] reported that the elastic modulus of perio- date lignin isolated from Pinus radiata is 4 GPa at 10 % moisture content. He also reported that the elastic mod- ulus of the isolated Klason lignin is 3 GPa at 8 % mois- ture content. However, these values may only be taken as approximations to the in situ polymer properties, because both the molecular structures and the spatial arrangements of these polymers differ substantially in their isolated forms and within the 3D assembly mode in the cell wall. The intricate 3D intertwining of wood polymers influ- ences the mechanical properties of wood cell walls. Therefore, the mechanical properties of the individual polymers must be investigated in situ to determine their influences on the mechanical performance of the wood at the cell wall level.
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Lignin-degrading activity of edible mushroom Strobilurus ohshimae that forms fruiting bodies on buried sugi (Cryptomeria japonica) twigs

Lignin-degrading activity of edible mushroom Strobilurus ohshimae that forms fruiting bodies on buried sugi (Cryptomeria japonica) twigs

The cultures were incubated at 25°C under fluorescent light (approximately 800 lux). For preparation of the inoculum, Strobilurus ohshimae was cultivated on sugi-PDA plate medium (see below), and the tip of the fungal colony was cut out from the agar medium by using an 8-mm cork borer. This agar plug was inoculated onto every culture. For the preparation of sugi-PDA medium, sugi wood meal was added to PDA medium until the final concentration was 2.0% (w/v), and its supernatant was poured into separate petri dishes after autoclaving at 121°C for 40 min.

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Reaction wood anatomy and lignin distribution in Gnetum gnemon branches

Reaction wood anatomy and lignin distribution in Gnetum gnemon branches

We have previously pointed out that changes in the ana- tomical and chemical characteristics of secondary xylem due to reaction wood formation in vessel-less angiosperms might be related to the ratio of the syringyl to guaiacyl units in lignin in the cell walls of normal wood, which func- tions in mechanical support. Those species with a higher ratio of syringyl to guaiacyl units form reaction wood on the upper sides of inclined stems or branches, whereas the species with a low ratio of syringyl to guaiacyl units pro- duce reaction wood on the lower sides of inclined stems or branches [11, 12]. However, this hypothesis was based only on results from tracheid walls of vessel-less angio- sperms. The axial components of the secondary xylem in G. gnemon includes both tracheids and fiber tracheids [13] (Fig. 1), so both tracheid types can serve a mechanical sup- port function in this species. Previous results obtained from the thioacidolysis method of wood meals indicated that the lignin in G. gnemon of normal wood is enriched in syrin- gyl units compared with those in reaction wood [14]. In the present study, the fiber tracheid walls on the lower side were strongly stained with Mäule reagent, but not strongly with phloroglucinol–HCl reagent (Fig. 5). By contrast, both rea- gents stained the tracheid walls (Fig. 5). However, when compared to the vessel walls, the tracheid walls were only weakly stained with phloroglucinol–HCl reagent (Fig. 5). The tendencies on lignin concentration of fiber tracheid and tracheid walls on the lower side in this study were simi- lar with the results on S/G ratio of normal wood reported by previous researchers [14]. Obtained results suggest that lignin of the fiber tracheid walls and tracheid walls on the lower side might be rich in syringyl units, although further researches, such as chemical analysis, are needed. There- fore, it can be concluded that our hypothesis regarding the relationships between reaction wood characteristics and the proportion of syringyl to guaiacyl units in lignin [11, 12] might also accept to gymnosperms with vessel element, G. gnemon as well as vessel-less angiosperms.
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Isolation of lignin–carbohydrate bonds in wood. Model experiments and preliminary application to pine wood

Isolation of lignin–carbohydrate bonds in wood. Model experiments and preliminary application to pine wood

hydrates in wood or isolated LCC fraction are fairly stable. The ozonized product was also rather stable toward acid hydrolysis. Benzylic ether bonds between lignin and polysaccharides (hexoses and pentoses) in Japanese red pine are proposed. Benzylic ether bonds may be detected in other wood species and in other lignocellulosic materials such as kraft pulps by using the procedures described in this article. Detailed information of the bonding pattern was not obtained and needs further investigation.

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Overcoming cellulose recalcitrance in woody biomass for the lignin-first biorefinery

Overcoming cellulose recalcitrance in woody biomass for the lignin-first biorefinery

Depending on experiment, 50- or 100-mg samples of cot- ton linter cellulose (Sigmacell; product No. S5504T) and milled wood particles from WT and transgenic poplars were suspended in 1:20 (w/v) ratios of ice-cold 99% TFA (Sigma-Aldrich) in 15-mL glass centrifuge tubes sealed with a Teflon ® -lined screw caps, and incubated at − 20 °C for 15 h. After incubation, samples were either vortexed with five volumes of absolute ethanol (0 h) or incubated for 5 h at 55 °C before vortex mixing in the ethanol solu- tion. Control samples in water were mixed with five vol- umes of ethanol. The insoluble solids and gels centrifuged at 1200×g in a swinging-bucket rotor for 5 min, and the pellets were washed four times with 12 mL of 80% etha- nol in water (v/v), followed by four rinses with water. For lignocellulosic poplar materials, absorbance of the brown solutions was determined between 400 and 700 nm and correlated to S-lignin composition. Duplicate 2-mL sam- ples of the TFA-ethanol solution were saved, and 0.5 mL of tert-butyl alcohol was added before the mixtures were dried under a stream of N 2 at 40 °C in 4-mL glass tubes.
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Lignin: Renewable Raw Material for Adhesive

Lignin: Renewable Raw Material for Adhesive

Biobased raw material like lignin used during manufacturing of wood and wood composite adhesive have been used extensively to replaced petro-che- mical based adhesive because of their easy availability, low cost and biode- gradability. Bio-based resources, such as lignin which is an abundant, consti- tute a rich source of hydroxyl functionality which is being considered as reac- tive raw material for the production of “adhesives”. Lignin is mainly used for production of wood and wood composite adhesives by blending with soy protein, grafting with another polymer and reacting with isocynates. In this review, lignin as suitable alternative raw material to conventional petroleum sourced materials used as a raw material for adhesives is discussed.
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Optimisation of Acid Hydrolysis in Ethanol Production from Prosopis Juliflora

Optimisation of Acid Hydrolysis in Ethanol Production from Prosopis Juliflora

The biochemical conversion process is similar to the process currently used to produce ethanol from corn starch. Enzymes or acids are used to break down a plant’s cellulose into sugars, which are then fermented into liquid fuel. Four key steps are involved. First, feedstock is pretreated by changing its chemical makeup to separate the cellulose and hemicellulose from the lignin in order to maximize the amount of available sugar. Second, hydrolysis uses enzymes or acids to break down the complex chains of sugar molecules into simple sugars for fermentation. Third, fermentation is used to convert the sugar into liquid fuel. Fourth, the liquid fuel is distilled to achieve a 95% pure form (fig. 2.7) (Zhu JY et al., 2009).
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Characterization of the lignin-derived products from wood as treated in supercritical water

Characterization of the lignin-derived products from wood as treated in supercritical water

As shown in Table 2, both sugi and buna woods were effectively converted to a water-soluble portion, methanol- soluble portion, and methanol-insoluble residue by super[r]

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Characteristics and Mechanicals Potentials of Wood Adhesives Manufactured with Grasses’ Lignins

Characteristics and Mechanicals Potentials of Wood Adhesives Manufactured with Grasses’ Lignins

140 g of each sample ( sorghum bicolor and Andropogon gayanus ) stems crushed and 980 ml of NaOH (0.7 - 1 M) were mixed in a reactor of 2 liters, and boiled at 170˚C during 3 hours. After cooling the boiled content during 2 hours, it was sieved to obtained black liquor at pH = 5.5 adjusted using sulfuric acid. Then, the precipitate lignin was filtrated on the vacuum and watch with distillated wa- ter till neutral. The lignin obtained was stoved in an oven at 45˚C during 48 hours [12].

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Chemical characteristics of surfaces of hardwood and softwood deteriorated by weathering

Chemical characteristics of surfaces of hardwood and softwood deteriorated by weathering

The lignin content in the albizzia wood surface decreased significantly after ex- posure to various weathering conditions, especially in the presence of water irrespe[r]

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