what steam pressure is the autoclave to heat treat wood
Abstract
Combined treatment with steam and oestrus was imposed on green Turkey oak (Quercus cerris L.) wood, both for sapwood and heartwood. Steaming was carried out in an autoclave at 100, 120, or 130 °C, and then a portion of the samples was heated in an oven for 2 h at 120 or 180 °C. Extraction with ethanol provided the greatest extractive contents in sapwood, and the extractive quantity decreased as the heating temperature was increased to 180 °C. In contrast, extraction with dichloromethane provided the greatest extractive content in heartwood, and no sizeable differences were found amidst the various treatments. Lignin amounts increased with rising treatment temperatures combined with steaming at 100 and 120 °C until the greatest value of 31.1% lignin content was reached. However, the lignin content decreased every bit the steaming temperatures rose to 130 °C. In all the combined treatments, the lignin content was greater in heartwood than in sapwood. Moreover, both steaming and heating applied individually produced no significant upshot on lignin content.
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Consequence of Combined Steam and Rut Treatments on Extractives and Lignin in Sapwood and Heartwood of Turkey Oak (Quercus cerris L.) Wood
Luigi Todaro,a,* Pasquale Dichicco,a Nicola Moretti,a and Maurizio D'Auria b
Combined treatment with steam and rut was imposed on green Turkey oak (Quercus cerris 50.) woods, both for sapwood and heartwood. Steaming was carried out in an autoclave at 100, 120, or 130 °C, and and so a portion of the samples was heated in an oven for 2 h at 120 or 180 °C. Extraction with ethanol provided the greatest extractive contents in sapwood, and the extractive quantity decreased as the heating temperature was increased to 180 °C. In contrast, extraction with dichloromethane provided the greatest extractive content in heartwood, and no sizeable differences were found among the various treatments. Lignin amounts increased with rising treatment temperatures combined with steaming at 100 and 120 °C until the greatest value of 31.1% lignin content was reached. Nonetheless, the lignin content decreased equally the steaming temperatures rose to 130 °C. In all the combined treatments, the lignin content was greater in heartwood than in sapwood. Moreover, both steaming and heating applied individually produced no significant effect on lignin content.
Keywords: Quercus cerris; Lignin; Extractives; Sapwood; Heartwood; Hydrothermal treatments; Steaming; Hydrothermal and thermal modification of forest
Contact data: a: School of Agricultural, Forestry, Food and Environmental Science. University of Basilicata, Five.le Ateneo Lucano x, 85100 Potenza, Italia; b: Department of Science. University of Basilicata, Five.le Ateneo Lucano 10, 85100 Potenza, Italy; *Corresponding author: luigi.todaro@unibas.it
INTRODUCTION
In general, hydrothermal treatments of wood induce a temporary or permanent alter and meliorate some woods characteristics. The actions of steam and oestrus on wood are circuitous because they involve changes in the physical and chemic nature of the forest microstructure and in the cell wall components. Steam causes swelling of the material accompanied by hydrolysis of sure compounds and solvation of various extractives. On the other hand, thermal treatment causes progressive degradation of the constituents of the wood cells, leading to the germination of numerous substances whose nature depends on the wood species, the samples size, and the procedure conditions.
Many studies have shown that the combination of high temperature and steam may cause changes in the chemical composition of wood (Fengel and Wegener 1989; Kosikovaet al. 1999). The changes in chemical limerick and wood structure in thermal processes are mainly caused by the degradation of hemicelluloses, cellulose, and lignin, which straight influences the physical and chemical properties of the woods (Stamm 1956, Weiland and Guyonnet 2003; Boonstra and Tjeerdsma 2006; Colina 2006; Esteves and Pereira 2009).
The consequence of hydrothermal treatment on chemical modification of locally grown, intermediate hardwood species such equally Turkey oak (Quercus cerris 50.), has non been studied very much. The natural range of this speciesis from Southern Europe to S-western Asia. Turkey oak wood could represent an of import resource for mount economies. However, low quality factors cause this kind of wood to be considered only for the everyman-valued use,i.eastward. as firewood. The primary limiting factors include the following: low dimensional stability, elevated internal tension, stiff swelling and shrinkage, and low durability, mainly in sapwood (Giordano 1981). Also, a difficulty in gluing (Lavisciet al. 1991) and a non very highly-seasoned surface colour (Tolvaj and Molnart 2006) have precluded, upwards to now, penetration of this wood in the article of furniture market place. Nevertheless, the color change is frequently viewed positively, especially in hardwoods, for which there is a potent difference betwixt heartwood and sapwood, such as Turkey oak.
No data accept been reported in the literature concerning the different chemical components between heartwood and sapwood for Turkey oak forest, although Lavisciet al. (1991) take reported that the nature and concentration of extractives for this kind of wood are quite different, principally in terms of the insoluble fraction. Turkey oak might be a valuable commercial wood, but its value is often degraded past a multifariousness of stains, most of which are due to extractives such equally tannins in the wood. These stains often tin can be prevented by working with wet wood and loftier-temperature steaming.
Lignins are circuitous polymers fabricated upwards ofp-hydroxyphenyl, guaiacyl, and syringyl units in various proportions, depending on the botanical type of the trees. In hardwood species, such equally oak species, lignin is composed of syringyl and guaiacyl units, with a trace ofp-hydroxyphenyl groups (Assoret al. 2009). Konovalovaet al. (2007) take stated that oak wood lignin of the guaiacyl blazon is located primarily in the middle lamella and, to a small extent, in ray parenchyma cells and in the walls of ring vessel elements. In contrast, syringyl lignin is located in the libriform cobweb walls and in the latewood portion.
The physical and chemical properties of lignin play an important role against the invasion of pests and pathogens; while for the forest product industries, lignin is considered 1 of the major barriers to an efficient extraction of cellulose fibers for pulp and paper product (Novaeset al. 2010). The same authors have reported that lignin has greater energy content than either cellulose or hemicelluloses.
Several studies support the theory that lignin content increases with rut treatment (Zamanet al. 2000; Esteveset al. 2008). Esteves and Pereira (2009) have suggested that the apparent increase in lignin content upon thermal handling of wood could not be considered pure lignin. In fact, numerous researchers have hypothesized that polycondensation reactions occur in the cell wall of other components, with consistent polymerization, thus increasing the apparent lignin content (Esteves and Pereira 2009). On the other manus, the increase in lignin content may not imply the germination of lignin during the process simply rather the reduction of the amounts of other wood components (Kamdemet al.2002)
Another aspect that should not be underestimated is the possibility of using lignin as a processing stabilizer for polystyrene and polyethylene (i.e. every bit a chemical that tin can be used during the processing of these polymers) instead of conventional organic stabilizers, which are toxic and more expensive (Pucciarielloet al. 2004). Considering that this polymer will likely exist used in the industrial sector in the future, one could then consider the possibility of inducing new polymerization in the woods by means of hydrothermal treatments, leading to significant increases in the availability of lignin. All the same, although lignin has been tried in diverse fields, information technology is all the same difficult to make apply of. I reason for this failure, every bit indicated by Funaokaet al. (1990), is the complexity of lignin structures.
Rowe and Conner (1979) take stated that extractives may influence most of the properties of wood and the performance of forest products because they can protect wood from decay and affect the caste to which the color changes upon exposure to light, the odor of the forest, and the emphasis of the grain pattern. Extractives may also have an influence in gluing, finishing, papermaking, and in contributing to the corrosion of metals in contact with forest. In add-on, the extractives have been shown to contribute to the dimensional stability of woods. Furthermore, they may have an influence in terms of wellness hazards. For example, the resin, tannic acid, pigment,etc. are considered to exist responsible for the color change in wood (Sundqvist 2004). In a report by Esteves and Pereira (2009) near of the extractives disappeared or were degraded during estrus treat-ment, especially the more volatile compounds.
Dinget al. (2011) constitute for Mongolian pine wood that there was an increase in the extractives content after heat treatment: 2.8% in the control sample, 3.2% in the sample treated in atmospheric steam, and 3.5% in pressurized steam. In contrast, González-Peñaet al. (2004) investigated the effect of extractives on thermo-treated wood degradation and did not discover any significant differences compared to controls.
The technological properties of lignin (durability, strength,etc.) and the extrac-tives (paintability, glueability) have a primary importance. Therefore, for the direct use of these components every bit a material for usage, the distribution and the quantity in the different parts of the wood (sapwood and heartwood) are the most of import factors for its characterization and use.
The main goal of this work was to evaluate the effect of unlike combinations of steaming and heating treatment conditions on the quantitative decision of extrac-tives and lignin in Turkey oak dark-green wood.
MATERIAL AND METHODS
Samples Preparation
The forest material used came from four copse growing in a high Turkey oak forest located in the Basilicata Region (Southern Italy). Green lumber pieces were used in club to avoid the possibility that natural or artificial drying might influence the characteristics of the woods (Estebanet al. 2005). Boards were cut radially from the logs, and nonstan-dard plainsawn specimens were extracted with the annual rings tangentially oriented. The wood specimens measured 50 × half dozen × 180 mm (in the tangential, radial, and longitudinal directions, respectively). Sapwood and heartwood were distinguished for each treatment. Twelve dissimilar treatments were performed on randomly selected samples, every bit indicated in Tabular array 1.
A full of 160 samples, 40 for each treatment, equally distributed between heartwood and sapwood, were initially used for the Control (Ctrl) conditions, steaming at 100 °C (ST100), steaming at 120 °C (ST120), and steaming at 130 °C (ST130) (Table one). After that, 40 samples were used for the beginning combined treatments: x for Ctrl+heating at 120 °C (H120), 10 for ST100+H120, ten for ST120+H120, and ten for ST130+H120 (Table 1). The other 40 samples were used for the second combined treatments: 10 for Ctrl+heating at 180 °C (H180), x for ST100+H180, 10 for ST120+H180, and 10 for ST130+H180 (Table1). The remaining samples (eighty specimens) were used for the other treatments: 20 for Ctrl, 20 for ST100, 20 for ST120, and 20 for ST130 (Tabular array 1).
Table 1.The Twelve Treatments and the Number of Specimens
Steaming Processes
Treatments of greenish woods were carried out at unlike temperatures and pressures by indirect steaming inside an autoclave (model Vapormatic 770/A). The instrument was sterilized past means of vertical charging, which was completely automatic, thermo-regulated, and controlled. The autoclave was equipped with a closed stainless steel basket (240 × 190 mm in diameter and height, respectively) and a microprocessor, which permitted the programming of various times and temperatures (from 100 to 130 °C). The maximum capacity of the autoclave was 23 L.
The cycles were the following:
ST100.From an ambient temperature (T) of about 24 °C, theT was increased to 100 °C over 20 min and was held constant at 100 °C for 20 min. Side by side, the T was decreased to l °C over 180 min. The total time was 220 min.
ST120.From an ambientT of about 24°C, theT was increased to 100 °C over twenty min and was held constant at 100 °C for 10 min to eliminate the residual air. Adjacent, theT was increased to 120 °C over 20 min and was held constant at 120 °C for 60 min. Finally, theT was decreased to 100°C over 40 min and to l°C over 180 min. The total fourth dimension was 330 min.
ST130. From an ambientT of about 24 °C, theT was increased to 130 °C over xxx min and was held constant at 130 °C for 10 min. Similar to the ST120 treatment, theT was decreased to 100 °C over 60 min and to 50 °C over 180 min. The total time was 280 min.
Heat Handling
A portion of the original samples used in the autoclave was so treated for two h in a small heating unit controlled with ±1 °C sensitively under atmospheric pressure level, using 2 unlike heat cycles: 120 and 180 °C. Side by side, the samples were cooled and weighed.
For determination of the extractive and lignin content, three random samples for each treatment and type of wood (sapwood and heartwood) were chosen. For the following determinations, half-dozen thousand was taken from each of the 24 samples (12 from sapwood and 12 from heartwood), extracted and ground with a pocket-size rotary blade machine. Additional experimental information is described in Todaroet al. (2012).
Determination of Extractives
The determination of extractives was quantified using the modified TAPPI CPPA Grand 13 method as described in Solvent Extractives in Pulp (1997). This method determines the amount of solvent-soluble, non-volatile cloth in wood and pulp. Equally reported in the method, two unlike solvent systems may be employed: dichloromethane or ethanol; the first gives lower amounts of extractives, while extraction with ethanol gives reproducible results and includes some boosted compounds. The extraction apparatus consisted of a 250 mL flask, a Soxhlet tube (40 mm in diameter), and a 300 mm Hallihan cooler. Cellulose thimbles (medium porosity and size of 33 × 80 mm) were used to filter the samples. For each of the 24 samples, the solvents used were ethanol and dichloro-methane, respectively. After extraction the cloth was dried using a rotary evaporator continued to a vacuum pump (Vacuubrand PC3001). For each extraction, two g of cloth was placed in a cellulose thimble, which was covered with a cotton ball to prevent loss of the wood. Each extraction was carried out for seven h; then, the solution was dried (upward to a pressure level of 20 mbar) in a previously weighed 25 mL flask. Finally, it was possible to calculate the extraction percentage by weighing the flask containing the residue.
Determination of the Lignin
The lignin determination was quantified past using a modified TAPPI T13 k-54 (1954) method. The Klason lignin content was determined from the amount of precipitate formed after sulfuric acrid attack on the extractive-complimentary material.
Each sample (1 grand) was stale and transferred to a 50 mL beaker. Then, 15 mL of 72% H2And thenfour was added. Subsequently, the samples were allowed to stand for two h in a 20 °C water bathroom, with frequent stirring. The samples were then done with a total of 560 mL of h2o into a 1 50 beaker and then that the H2SO4 concentration was diluted to 3%. The beaker was covered with a big watch glass, and the mixture was refluxed for 4 h, maintaining a abiding volume past calculation water. The solution was then filtered by using a vacuum system (Vacuubrand PC3001 model) with a polyvinyldifluoride (PVDF) membrane. The resulting residue was dried in an oven fix at 45 °C for 12 h. Samples were so removed from the oven, cooled, and weighed past using a balance having 0.001 thousand accurateness. The lignin content was determined by comparing the weight of the rest remaining with the original weight of fabric.
RESULTS AND Discussion
Extractives
The quantities of extractives with ethanol were found to be substantially greater than those obtained with dichloromethane (Fig. 1). These results tin can be explained past considering the polar nature of the compounds nowadays in the lignin and extractives. Dichloromethane is a relatively nonpolar solvent (Ɛ = 8.9;E T = 41.1), while ethanol is more polar (Ɛ = 24.5;E T = 51.9) (Reichardt 1979).
When ethanol was used as the solvent (Fig. 1), a greater content of extractives was plant in sapwood treated with ST120+H120 (nine.9%), followed past ST130+H120 (eight.nine%). Turkey oak sapwood and heartwood showed considerable differences in terms of extractives using both methods. The estimation of this upshot is quite complicated; a likely hypothesis may be that more complex tannins exist in heartwood than in sapwood (Roux 1957; Hillis 1968). Rowe and Conner (1979) have reported a particularly notable dissimilarity for oak forest betwixt the components of sapwood and heartwood.
Fig. one. Extractives content using ethanol with sapwood (Sapw Eth), heartwood (Hertw Eth), and average values for all treatments
In terms of boilerplate values, the quantity of extractives appeared to increase with steaming treatment. Nevertheless, a decrease resulted under the most farthermost procedure conditions (in combination with heating to 180 °C) (Fig. ii). The greatest quantity of extractives was obtained with steaming at 130 °C without heating. It is important to note that with the combination of steaming and heating to 180 °C, the extractive percentage obtained dropped sharply in all samples, leading to the supposition that a fixed amount of extractive remained. The crusade of this drop should be investigated.
Fig. two. Influence of combined treatment on average extractive content
The effect of steaming on wet Turkey oak woods, which is particularly difficult to treat, was not completely clear in this report. An explanation for these results could involve the presence of pressurized steam in the experiment to which the dark-green wood was submitted (Dinget al. 2011). As suggested by Rowe and Conner (1979) for oak wood species, a complete understanding of the phenomena of stain or other problems for Turkey oak wood will exist attainable only when data regarding the chemistry of heartwood and sapwood extractives has progressed considerably.
Assoret al. (2009) have confirmed that the softening of wood begins between fifty and 100 °C, depending on diverse parameters and species. The authors stated that the presence of h2o in wood during steaming certainly affects degradation of the compo-nents of the wood by promoting hydrolysis, specially in the presence of acetic acrid, in addition to creating conditions favorable for the condensation of lignin.
Esteveset al. (2008) have reported that the extractives content increases significantly with mass loss, followed by a subtract, despite the fact that most of the original extractives disappeared from the treated wood.
While a clear pattern was displayed when ethanol was used, confusing and unclear results were obtained when dichloromethane was used (Fig. 3). In any case, the quantity of extractives in heartwood was clearly greater than that in sapwood. These results can be understood by because that heartwood has a greater amount of nonpolar extractives than sapwood. This hypothesis should be farther investigated. Hillis (1968) has reported that heartwood presents more phenolic-type extractives (e.m.flavonoids), while sapwood contains starch, soluble sugars, and triglycerides. As reported by Santanaet al. (2009), polar solvents requite high extraction efficiencies. However, they also extract other undesirable polar compounds present in the samples. With a nonpolar solvent, such as dichloromethane, the extraction of phenols would crave a previous acidic digestion of the analytes.
Fig. three. Extractive content using dichloromethane in sapwood (Sapw Dichl), heartwood (Heartw Dichl), and boilerplate value for all treatments
Hillis (1968) has stated that extractives are by and large detectable in rays and that they tin can also form coatings on the prison cell wall and on the pits, or they can penetrate the cell wall itself. These different locations inside the tree are ane reason why one solvent extraction cannot extract all the extractives at in one case and why the use of several solvents of unlike polarity can increment the total removal of extractives (Caron 2010).
Our results using dichloromethane showed no noteworthy results regarding the influence of different steaming or heating methods. The amount of extractives obtained with dichloromethane seemed to be independent of treatments, like to reports by González-Peñaet al. (2004).
Lignin
When comparison sapwood and heartwood (Fig. 4), the lignin contents were always greater in heartwood, with the only exceptions coming from samples treated only with heat (Ctrl+H120 and Ctrl+H180). Similar results were found past Wahabet al. (2011) inAcaciahybrid wood treated with hot oil, where the lignin content of heartwood was greater than that in sapwood.
Fig. 4. Lignin content in sapwood and heartwood for all treatments
The differences in chemical composition in the wood, in terms of extractives, cellulose, and hemicellulose (Caoet al. 2012) content, could be due to the lignin concentration in sapwood and heartwood.
The greatest percentage of lignin was found in samples treated with a combination of steaming at 100 and 120 °C and heating to 180 °C. In samples treated with the combination ST100+H180, the amounts of lignin were 29.1% from sapwood and 30.1% from heartwood, while samples treated with ST120+H180 yielded 28.6% of lignin from sapwood and 31.1% from heartwood. The minimum amount of lignin was obtained from samples treated only with steaming, mainly at 120 and 130 °C.
According to Bourgois and Guyonnet (1988), Zamanet al. (2000), and Andersonset al. (2009), the percentage of lignin content is positively related to the increase of heating temperature (Fig. 4). Moreover, this relationship for Turkey oak was observed only with high temperature heating and a previous steaming treatment.
In fact, past comparing all of the lignin content values to untreated samples (Ctrl), the greatest lignin extractions were obtained with the combination of steaming and heating at 180 °C. Even when the steaming temperature was increased to 130 °C, the lignin content decreased (Fig. 5). With the combination of steaming at 120 °C and heating to 180 °C, it was possible to extract 21.five% more lignin than untreated samples. Moreover, it was observed that both steaming and heating applied individually produced no positive or substantial effect. The amount of lignin in the steamed wood (partially in ST 100, totally in ST 120 and ST130) decreased compared to the Ctrl, principally in sapwood.
Fig. 5.Relative lignin content compared to Ctrl in sapwood and heartwood
These results have been confirmed in a recent paper past Dashtiet al. (2012) forQuercus infectoria. These authors also plant a reduction of lignin content and high-lighted the difference in terms of permeability and improvidence coefficient between sapwood and heartwood. In add-on, they stated that the presence of tyloses in heartwood, of which Turkey oak is filled, has a significant upshot on the final impact of steaming treat-ment on lignin content, probably due to reduction of cellular wall structure destruction, which lowers the water vapor diffusivity rate through wood.
Funaokaet al. (1990) have indicated that water contained in wood accelerates the condensation of lignin because water decreases the softening temperature of lignin, allowing the catamenia of lignin at a lower temperature.
Further assay of the results indicated that steaming should not exceed 120 °C. Indeed, increasing the temperature upwardly to a maximum of 180 °C increased the amount lignin extracted, just when the samples were treated with steam exceeding more than 120 °C, the amount of lignin extracted decreased (Fig. v).
The increasing amount of lignin content with heat treatment could be due to some of the thermal degradation products of carbohydrates probable being trapped in the lignin (Yildizet al. 2006). Several authors have reported the formation of condensation products and possible cross-linkage between lignin and polysaccharides (Funaokaet al. 1990; Košíkováet al. 1999; Sivonenet al. 2002). Equally reported by Assoret al. (2009), lignins are strictly associated with noncellulosic polysaccharides that form so-called lignin-carbohydrate complexes (LCCs).
In fact, the loss of polysaccharide material during heat treatment leads to an increase in the lignin content of the wood. These results have also been reported by Wahabet al. (2011). Kamdemet al. (2002) have suggested that the increase in lignin conten is probably due to the reduction of other wood components and does not imply that new lignin is formed. Andersonset al. (2009) too established that the lignin content increases due to the degradation of compounds that are not thermally stable.
Steam can have different effects on the structure of lignin. It can promote hydrolysis reactions on polysaccharides (Fengel and Wegener 1989), causing an increment of alcoholic aliphatic functional groups that are able to react with the lignin scaffold. Similarly, the presence of h2o at high temperatures tin cause oxidation reactions with the formation of new alcoholic functional groups on the lignin construction. Water can also induce hydrolysis of saccharides, which increase the amount of lignin due to reactions of these new alcohols with lignin itself. Furthermore, thermal treatment can induce reorgan-ization of the lignin past increasing its cross-linked structure due to unproblematic reorganization of the structure and/or oxidation processes (Huanget al. 2012).
It is evident that hydrothermal treatment promotes an increase of the corporeality of lignin recovered in the samples. It is as well apparent that the primary effect was obtained with heartwood (Fig. 4 and Fig. v), while sapwood gave an increase in the amount of lignin only under the well-nigh drastic conditions (ST100+H180; ST1200+H180). Thus, the steam treatment induced alteration of the wood compounds, increasing the consequence of the thermal treatment in the heartwood.
In sapwood we observed a progressive reduction in the amount of lignin from ST100+H180 to ST130+H180; while with heartwood, no articulate effect was evident (Fig. 5). In this case, extensive hydrolysis of polysaccharides caused by hot h2o tin produce an increase in the cantankerous-linked construction of lignin (Funaokaet al. 1990; Košíkováet al. 1999). The "new" cross-linked lignin forms a structure more than resistant to belittling decision.
It is noteworthy that the steam handling at 130 °C and the thermal treatment at 180 °C gave a lower corporeality of lignin. It is hard to explain this result. Nosotros hypothesize that with these weather, reorganization of the lignin structure immune the formation of a more rigid cross-linked structure that is more resistant to the acidic treatment used in the conclusion of lignin.
CONCLUSIONS
The aim of this study was to understand how 12 different hydrothermal treatment conditions influence the extractive and lignin content of Turkey oak (Quercus cerris L.), ane of the forest species with the largest planted expanse in Southeastern Europe. Upwards until now, this species has been inadequately investigated.
- The quantities of extractives institute with ethanol were substantially greater than those obtained with dichloromethane. These results tin can exist explained by considering the polar nature of the compounds nowadays in the lignin and extractives.
- In contrast to ethanol, by using dichloromethane, the quantity of extractives was greater from heartwood than from sapwood. In terms of average value, the quantity of extractives appeared to increase with the steaming treatment. All the same, the amount of extractive content decreased when steam was combined with heat at the extreme temperature of 180 °C.
- Compatible results for lignin content were found for sapwood and heartwood. The most lignin was constitute in samples subjected to combined treatments of moderate steaming (100 to 120 °C) and farthermost heating (180 °C). In ST120+H180 treatment, a 21.5% increment in the amount of lignin was obtained compared to the untreated samples.
- In all samples subjected to combined treatments, the content of lignin in heartwood was greater than lignin content in sapwood. Moreover both steaming and heating applied individually produced no positive and sizeable effect on lignin content compared to the command.
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Article submitted: Nov. 23, 2012; Peer review completed: Dec. 20, 2012; Revised version received and accepted: Feb. 8, 2013; Published: February 15, 2013.
Source: https://bioresources.cnr.ncsu.edu/resources/effect-of-combined-steam-and-heat-treatments-on-extractives-and-lignin-in-sapwood-and-heartwood-of-turkey-oak-quercus-cerris-l-wood/
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