Modifying the radiation ratio of tonewoods through wood degradation

Modifying the radiation ratio of tonewoods through wood degradation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Modifying the radiation ratio of tonewoods through wood degradation Keenan Nefdt, Martina Meincken This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4280659/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This work investigates different wood modification techniques to modify the acoustical properties of tonewoods, in particular the sound radiation ratio (R). The treatments used were heat- and fungal exposure, as well as immersion into NaOH and Na 2 SO 3 solution and a combination of the most successful treatments. All initial experiments were performed on pine ( Pinus patula ) due to cost factors, before replicating the best performing treatment on high quality spruce tonewood ( Picea abies ). The main objective was to reduce the hemicellulose content without severely degrading cellulose, which results in a reduction of density, while maintaining, or even improving the elasticity (MOE L ), which results in an increase of R. Overall, the combined heat-fungal and heat-sodium treatments performed best and increased R by up to 20%. Sodium treatment led to the best increases in R, but compromised the wood structure in spruce and the treatment protocol needs to be developed further. Consequently, the most successful wood treatment to improve acoustical properties was determined to be exposure to white rot combined with heat treatment. improved radiation ratio wood degradation heat treatment fungal exposure sodium treatment Figures Figure 1 Figure 2 Figure 3 Figure 4 1. INTRODUCTION For centuries luthiers strived to enhance the sound quality of their musical instruments. Some copied the methods and techniques of their predecessors, while others tried new techniques, but the results were not always successful. This endeavour continues today as luthiers are trying to understand why some of the older instruments have a better sound quality. Most of those attempts were directed towards the violin. Wood used to manufacture instruments is referred to as tonewood, or resonance wood. The quality of the produced sound depends on the elastic properties of the wood and how well it can oscillate. The sound quality of tonewoods can be best described through the radiation ratio (R) which is defined as R = √ MOE/ρ 3 . A significant difference can be observed between high- (15) - and low- (9) quality soundboards. Some of the famous Stradivari violins have R-values reaching 16 and above, whereas even the best quality modern violins tend to reach a maximum R of 12–15. The reason that old instruments have a much higher R value can only be explained by partial wood degradation, which reduced the density, without affecting the MOE, or speed of sound, too much. Various attempts were made to improve the sound quality of wood through artificial ageing. The ones showing the most promise is heat treatment and fungal degradation (Danihelová et al. 2022 ; Rang et al. 2016 ; Zhu et al. 2016). Previous studies have shown that the most important wood characteristics for good sound quality are MOE – which directly affects the speed of sound - and ρ (Zerbst et al. 2018 ). An increase in the MOE and lowering of ρ results in a higher R value. Soundboards easily transmit vibrations to the edges and are good sound radiators and typically have a low ρ and high MOE with a high sound radiation ratio and tend to resonate lower frequencies much clearer and louder than other wood species (Yoshikawa, 2007 and 2014). Various attempts were made to improve the sound quality of wood through artificial ageing i.e., heat treatment and fungal degradation (Danihelová et al., 2022 ; Rang et al., 2016 ; Zhu et al., 2017 ). Previous studies have shown that the most important wood characteristics for good sound quality are MOE – which directly affects the speed of sound - and ρ (Zerbst et al., 2018 ). An increase in the MOE and lowering of ρ results in a higher R value. In previous studies it was observed that low and moderate thermal exposures (110°C– 175°C) do not change acoustic properties significantly (Gadd and D’Arcy, 1986 ; Zerbst et al., 2018 ). Thermal treatment between 160°C and 220°C was found most suitable to degrade hemicelluloses and lignin, as desired for acoustic changes (Esteves and Pereira, 2009 ; Výbohová et al. , 2018; Zerbst et al., 2018 ), because at these temperatures the desired density decrease is obtained. At temperatures above 250°C cellulose chains start to degrade, which then also affects the MOE. However, exposure to high temperatures for a short time may prove to be beneficial in improving the acoustic properties and was included in this experiment. Obataya (2017) studied the effect of artificial hydrothermal ageing on the acoustic properties of wood. Treatment between 1 and 7 days at a RH of 57–64% was found to increase the specific dynamic Young modulus (E’/ρ) and decrease tan (δ), which indicates that heating at intermediate RH can improve the acoustical properties. Schwarze et al. ( 2008 ) discovered the presence of fungi, such as Physisporinus vitreus and Xylaria longpipes in the soundboard of old violins, which led to a decrease in hemicellulose content that might be responsible for the higher radiation ratio. Fungal degradation is a possible approach for the improvement of acoustical properties in wood, as the degradation of polysaccharides, such as hemicelluloses and lignin can have a positive effect on the acoustic properties. Fungi are known to deposit large amounts of organic acids as part of their natural metabolism that accumulate as oxalate salts along their hyphae. These salts form crystalline structures along the hyphae (Cromack et al., 1977 ), which leads to an increase in c and MOE L . These findings suggest that extended incubation periods with fungi can improve c up to a point where degradation of the cell wall occurs. It can therefore be concluded that the appropriate fungus capable of secreting a large amount of oxalate salts will improve acoustic properties of wood. Wood degrading fungi are typically grouped into white rot and brown rot, depending on the wood components they attack. White rot fungi degrade cellulose, hemicellulose and lignin, while brown rot degrades only hemicellulose and cellulose. The main objective of this study was to decrease the wood density by removing hemicelluloses and part of the lignin, without compromising the strength provided by the cellulose. Therefore, the effect of degradation caused by both brown and white rot fungi was analysed. Not much research exists dealing with chemical treatment of sodium hydroxide (NaOH) and sodium sulfite (Na 2 SO 3 ) for improvement of acoustical wood properties. The selection of these two compounds for this study is based the fact that recent studies found high levels (1000 ppm) of Na and other elements (e.g., K, Cl, Ca, Cu and Zn etc.) residing in the cell wall structure of violins made from Stradivari and Guarneri (Taia et al., 2017 ; Su et al., 2021 ). A further assumption is that timber companies made use of salt as preservative in the waterways used to move logs, which could have, at some point, had a positive implication on the chemical structure of musical instruments (Gug, 1988 ). The above findings suggest that some minerals added via chemical or preservative treatment may have been used that improved the acoustical properties of historical musical instruments over time. Studies have found that alkaline treatment increases the crystallinity index of cellulose (Xu et al., 2020 ), which might result in improved acoustical properties. Both sodium compounds were found to reduce the density of wood by degrading hemicellulose and lignin, while leaving the cellulose intact (Wachter et al., 2019 ; Li et al., 2021 ). Compared to acids (i.e., H 2 SO 4 ), alkaline solutions do not damage the S2-layer, but loosen the middle lamella, where the largest proportion of hemicellulose resides especially, if combined with thermal treatments of 100°C and 120°C. Moreover, the combination of the two compounds was found to degrade hemicellulose more effectively (Maturana et al., 2022 ; Kim et al., 2020 ). The benefits of an increased crystallinity index of the cellulose were shown to improve the acoustical properties of wood (Miao et al., 2021 ; Wang et al., 2019 ). This implies that any substance capable of increasing the crystallinity in wood may have a beneficial impact on the vibro-acoustical properties of wood, as soundwaves can move more easily through a crystalline structure than amorphous materials. NaOH was found to improve the crystallinity index of cellulose by selectively removing amorphous hemicellulose (Qi et al., 2023 ; Barman et al., 2020 ). However, alkaline treatments may decrease the crystallinity in wood at higher concentrations and longer exposure times (Xu et al., 2020 ; Nakano, 2010 ). The aim of this study is to modify and improve the acoustic properties of wood through various treatments: heat treatment, fungal exposure, UV exposure, sodium hydroxide (NaOH) and sodium sulphate (Na 2 SO 3 ) treatment. These treatments are expected to decrease the hemicelluloses, lignin and extractive content and therefore the density of wood, without significantly altering the MOE and therefore improve R. 2. MATERIALS AND METHODS 2.1 Wood Radially cut pine ( Pinus patula ) samples were used to determine the most suitable treatment, which was then repeated on tonewood spruce. The wood was cut from the sapwood part of boards originating from mature trees. Density, moisture content (MC) and the speed of sound (c) were measured before and after treatment. Sample sizes were 150 x 55 x 20mm for heat treatment, 60 x 20 x 15mm for fungal exposure, and 60 x 40 x 20mm for sodium, treatment. The sample sizes were different to accommodate the different exposure environments. For the sodium and fungal exposure samples smaller samples are required to ensure full saturation / coverage. All samples were stored for at least one month in a conditioning room at 65% RH and 20°C, before analysis and all measurements were performed at least in triplicate. High quality spruce ( Picea abies ) tonewood was obtained from a luthier in Pretoria, South Africa (Hannes Jacobs) and used to determine if the successful changes in acoustical properties of the optimum treatment could be transferred between wood species. 2.2 Treatment methods Thermal treatment was performed in an oven at temperatures of 160, 180, 200, 230 and 250 o C for times ranging from 5 minutes to several hours. For temperatures above 200°C, the wood blocks were wrapped in aluminum foil to prevent surface discolouration and charring. The experimental procedure was as follows: 160–200°C for 1 to 8 h, 230°C for 10-, 30 min and 1 h and 250°C at 5-, 15-, 30 min and 1 h. The high temperatures were chosen to ensure that hemicellulose degradation took place. Sixteen samples were exposed to brown rot ( Laetiporius sulphurous ) and white rot ( Schizophyllum commune ), respectively. To keep the fungus alive, the samples were placed in closed plastic containers with paper towels, which were wetted on a weekly basis. To obtain a successful spread rate, separate pine samples were pre-exposed for 8 months to start the fungal activity. The pre-exposed samples were then placed together with the treatment samples and left for incubation of 1, 2, 6 and 20 weeks. Five samples were removed for each exposure time, the fungus was scraped off and the wood was carefully dried in an oven at 40°C for 24 h. For chemical treatment in saline solution, samples were fully submerged in NaOH and Na 2 SO 3 for 8, 24, 48, 72, 120 and 168 h. Four samples were removed for each exposure time and washed in distilled water for 24 h to remove any excess NaOH and Na 2 SO 3 , before drying in an oven at 100°C for 24 h. Samples were also exposed to a combined NaOH + Na 2 SO 3 solution for 8, 24, 48 and 72 h. After treatment all samples were stored in a conditioning room for 2 weeks before measuring their acoustical properties to ensure that the physical changes are not just temporary. All measurements were performed at least in triplicate. 2.3 Measurement of physical properties The speed of sound (c) was determined with a Lucchi meter, which determines the time an ultrasound pulse requires to travel from the emitter to the receiver to determine c in m/s. C was measured along the grain at three different locations for each piece of wood. The length and MC of the wood need to be input into the instrument beforehand to obtain correct values for c. The average of the three measurements along each sample was used to calculate R. To determine the MC, 5 pieces were cut from each board and the MC determined with the equation: MC (%) = 100 * (m-m 0 )/m The density was determined before and after each treatment after conditioning the samples for 2 weeks at 20 o C and 65% RH by weighing the sample and calculating the volume. R was calculated according to its definition by Schelleng ( 1982 ): R = c / ρ Bucur ( 1987 ) showed that the specific dynamic Young modulus (MOE/ρ) can be derived from ultrasonic speed of sound measurements and MOE L was accordingly determined by: MOE Y = c * ρ 2.4 Combined treatment approach The treatments that showed the largest improvement in R - in this case treatment with white rot ( S. commune ) and NaOH solution – were combined with the heat treatment that had the largest improvement in R (one hour at 250°C). The most successful combined treatment was repeated on spruce tonewood, and the wood samples were prepared and treated in the same way as described above. 2.5 Representation of results and statistical analysis The distribution of data was checked for normality with the Shapiro-Wilk test. The statistical analysis result was determined through a Kruskal-Wallis test, followed by a post-hoc Dunn’s test to determine significant differences indicated by different letters. The significance level was p = 0.05. All results are presented as average values with error bars depicting the standard deviation. All graphs were plotted with OriginLab . 3. RESULTS AND DISCUSSION The following graphs show the change in R after treatment. A positive ΔR correlates to an improved value of R, which means that the treatment was successful in decreasing the density without affecting the MOE considerably. 3.1 Heat treatment Figure 1 shows that lower exposure temperatures slightly reduced R, which is not desirable to improve the acoustic properties. Furthermore, the exposure time did not have any statistically significant effect on ΔR for temperatures below 200 o C. However, the effect of exposure time on R becomes noticeable above 200°C with the largest difference between exposure times at 250°C. The largest improvement in R of 8% was obtained after exposure to 250°C for 1 h. The improvement in R can be linked to a decrease in ρ while maintaining or increasing MOE, as highlighted in Table 1 . Table 1 changes in ρ, c, MOE Y and R as function of the exposure temperature. Treatments that reduced ρ and maintained or improved MOE Y are highlighted T (°C) t (h) Δ ρ (%) Δ c (%) Δ MOE sd (%) Δ R (%) 160 1 -1.22 ± 0.40 -0.76 ± 0.71 -2.71 ± 1.60 0.47 ± 0.67 2 -1.18 ± 0.54 -1.80 ± 1.65 -4.67 ± 3.44 -0.62 ± 1.54 6 -1.09 ± 0.55 -1.71 ± 4.07 -6.86 ± 4.30 -0.64 ± 3.63 8 -1.53 ± 1.74 -2.84 ± 1.38 -7.01 ± 3.58 -1.31 ± 1.85 180 1 -1.13 ± 0.45 -1.74 ± 2.02 -4.51 ± 4.13 -0.62 ±1.86 3 -0.87 ± 0.88 -3.02 ± 1.22 -6.75 ± 2.64 -2.16 ± 1.38 6 -2.34 ± 1.16 -3.63 ± 0.98 -9.28 ± 2.71 -1.32 ± 0.82 8 -2.25 ± 0.23 -3.28 ± 0.80 -8.56 ± 1.43 -1.05± 0.94 200 1 0.01 ± 0.52 -5.60 ± 2.33 -10.84 ± 4.21 -5.60 ± 2.59 3 -1.04 ± 1.43 -4.44 ± 2.38 -9.56 ± 5.25 -3.44 ± 2.02 6 -2.44 ± 1.59 -5.54 ± 3.26 -12.81 ± 7.21 -3.20 ± 2.23 8 -2.57 ± 0.73 -5.74 ± 2.17 -13.37 ± 4.53 -3.26 ± 1.67 230 0.17 -0.09 ± 0.13 -2.52 ± 1.63 -5.04 ± 3.09 -2.42 ± 1.70 0.5 -1.17 ± 0.31 -2.43 ± 3.73 -5.81 ± 7.30 -1.28 ± 3.68 1 -3.06 ± 1.58 1.16 ± 0.92 -0.82 ± 1.2 4.38 ± 2.50 2.5 -3.54 ± 2.24 3.27 ± 0.83 2.90 ± 3.50 7.09 ± 2.17 250 0.08 0.15 ± 0.06 -2.95 ± 1.17 -5.66 ± 2.29 -3.09 ± 1.15 0.25 0.06 ± 0.41 -1.66 ± 1.41 -3.23 ± 2.57 -1.71 ± 1.67 0.5 1.70 ± 0.71 0.88 ± 0.79 3.50 ± 1.67 -0.81 ± 1.11 1 -4.46 ± 0.88 3.21 ± 0.43 1.77 ± 1.17 8.04 ± 1.15 De Rolleri et al. ( 2023 ) report that an increase in exposure temperature and time improves MOE at temperatures above 120°C. However, statistical analysis of our results shows no significant difference for different exposure temperatures and times for temperatures below 200°C, which is similar to what was reported by several other authors (Kučerová et al., 2016 ; Kocaefe et al., 2008 ; Zhao et al., 2008 ; de Jesus et al., 2022 ; Mania and Skrodzka, 2020 ). The main cause for the increase in R is a reduction in density as extractives and hemicelluloses are removed as volatile components during thermal treatment, which results in a mass loss (Holeček et al., 2017 ; Tumen et al., 2010 ; de Jesus et al., 2022 ; Zatloukal et al., 2021 ; Akgül et al., 2007 ; Wang et al., 2022 ). The increase in MOE Y is caused by the increased crystallisation of hemicellulose and cellulose, which was also found by other authors (de Jesus et al. 2022 ; Zatloukal et al. 2021 ; Akgül et al. 2007 ). The best thermal treatment of 250°C for 1 h was repeated on spruce to ensure that the results can be translated between wood species. The increase in R was somewhat smaller for spruce than for pine, but with and average ΔR = 5.89% still noteworthy. 3.2 Fungal degradation White rot showed a much faster spread rate than the brown rot after 20 weeks of incubation and both brown ( L. sulphurous ) and white rot ( S. commune ) samples showed a significant reduction in ρ with an increase in exposure time, which translates into an increase in R, as can be seen in Fig. 2 . The changes in c, ρ, MOE Y and R are highlighted in Table 2 (brown rot) and 3 (white rot). Table 2 The average change in ρ, c, MOE Y and R of pine incubated with brown rot ( L. sulphurous ) with standard deviations t (weeks) Δ ρ (%) Δ c (%) Δ MOE L (%) Δ R (%) 1 -0.35 ± 0.11 1.03 ± 0.64 1.73 ± 1.33 1.38 ± 0.61 2 -0.53 ± 0.36 -1.17 ± 1.63 -2.81 ± 3.43 -0.65 ± 1.44 6 -1.21 ± 0.08 1.94 ± 0.91 2.67 ± 1.85 3.19 ± 0.90 20 -1.01 ± 0.98 5.43 ± 1.48 10.06 ± 3.40 6.51 ± 1.73 Table 3 The average change in ρ, c, MOE L and R of pine incubated with white rot ( S. commune ) with standard deviations. t (weeks) Δ ρ (%) Δ c (%) Δ MOE L (%) Δ R (%) 1 -0.38 ± 0.07 2.02 ± 1.24 3.69 ± 2.51 2.41 ± 1.26 2 -0.37 ± 0.08 0.28 ± 1.21 0.2 ± 2.42 0.66 ± 1.24 6 -1.32 ± 0.11 2.61 ± 1.90 3.92 ± 3.76 3.98 ± 2.00 20 -3.50 ± 1.10 7.15 ± 1.78 10.79 ± 3.06 11.05 ± 2.81 After 20 weeks of exposure, brown and white rot reduced ρ by about 1% and 3.5%, respectively, which lead to an increase in R of about 6% and 11%. The treatment successfully reduced ρ without negatively affecting MOE, which allows the conclusion that the fungi degraded predominantly lignin and hemicelluloses without compromising cellulose. The results show that fungal degradation can indeed improve ρ. The density loss caused by the two fungi was similar, but brown rot had a slower spread rate compared white rot. Significant changes in ρ, MOE Y and R occurred after an exposure time of 6 weeks, which was deemed to be a more feasible time to improve tonewood than 20 weeks. Therefore, the fungal treatment of spruce with to white rot was repeated with an exposure time of 6 weeks. Unfortunately, R in spruce increased only slightly by 0.31%, which is similar to what others have reported (Rennenberg et al., 2008 ). This indicates that degradation did take place in spruce to some degree and that longer exposure times may be needed to obtain a more significant reduction in density. The lower increase in R in spruce can be explained by the fact that the tonewood has been seasoned for a very long time and reached a very stable conformation, which made it more difficult for the fungi to penetrate the wood. Furthermore, S. commune may not be the most suitable white rot fungus to decrease the density in spruce and another species may yield better results. 3.3 NaOH and Na 2 SO 3 treatments Figure 3 highlights the changes in R after treatment with the two sodium solutions and a combination of both solutions. Generally, the NaOH solution had a more positive effect on R compared to the Na 2 SO 3 solution, or the combination. Initially both the 0.2 M NaOH and Na 2 SO 3 solution significantly decreased R, which is undesirable. On average, the NaOH solution resulted in positive ΔR values between 2 and 4% for all exposure times and independent of the concentration. The Na 2 SO 3 solution showed lower increases in R and no clear trend, which concentration yields better results. This shows clearly that a NaOH solution is more effective in improving R for exposure times up to about 160 h, after which ΔR starts to decrease. It can be assumed that higher exposure times damage the cell wall structure, resulting in a decrease of structural integrity and therefore MOE and R. The density reduction was found to be significantly greater at higher concentration and longer exposure time for both sodium treatments. Zimmermann et al. ( 2007 ) explained that increased NaOH concentration degrades hemicellulose, and that mannose is the most vulnerable to NaOH. This was confirmed by various other studies (Zhang et al. 2016 , Zhao et al. 2008 and Barman et al. 2020 ). Unfortunately, the sodium treatment could not be replicated on spruce, as it led to cracks and honeycombing in the wood after drying. This may be caused by the fact that the NaOH did not penetrate the spruce wood well – probably because the wood was very well seasoned, which caused uneven drying after sodium treatment that led to cracking of the surface. 3.4 Combined treatments The most promising treatments to improve R were the fungal treatment with white rot for 6 weeks, heat treatment at 250°C for 1 h and sodium treatment with 0.2 M NaOH treatment for 120 h. These were combined to see if the combination would improve R even further and heat treatment of 250°C for 1 h was applied to the samples previously exposed to fungal treatment and sodium treatment, respectively. Table 4 highlights the changes in R for pine and spruce for the combined treatments and the results from the best performing individual treatments. Table 4 Improvement in R after heat-, fungal- and sodium treatment, as well as combined treatments Wood Type Treatment Exposure time ΔR (%) Pine white rot 6 weeks 3.98 ± 2.00 Pine white rot + heat 6 weeks, 1 h 13.34 ± 2.80 Pine 0.2 M NaOH 120 h 5.84 ± 0.93 Pine 0.2 M NaOH + heat 120h, 1 h 19.83 ± 2.36 Spruce white rot 6 weeks 0.31 ± 0.58 Spruce white rot + heat 6 weeks, 1 h 5.45 ± 3.13 Spruce 0.2 M NaOH 120 h N/A Spruce 0.2 M NaOH + heat 120 h, 1 h N/A The combined fungal / heat treatment showed a significant increase in R of more than 10% in pine wood compared to fungal exposure alone, which is a significant improvement. In spruce the combination increased ΔR from 0.3% for fungal treatment alone, to about 5.5%, which is also a good improvement. The combined sodium / heat treatment improved R in pine wood to about 20%, which is 14% more than the sodium treatment alone. This shows that sodium treatment followed by heat treatment is highly effective in improving the acoustic properties of pine wood. The combined sodium / heat treatment could unfortunately not be repeated on spruce, because the sodium solution compromised the wood structure and led to cracking and honey combing. This can probably be explained by the fact that the spruce wood has been well seasoned, which made penetration of the dry and stabilized wood very difficult. The penetration depth of pine and spruce was determined in a subsequent experiment on larger wood blocks. The penetration depth of the pine wood increased linearly with time, which means that the small sample blocks for the experiment were fully saturated after a few days. On the other hand the penetration depth in spruce remained around 5 mm over a measurement period of 18 days. The fact that the spruce wood is fairly impenetrable also explains why the fungal treatment of spruce was significantly less effective when compared to pine. 4. CONCLUSIONS The aim of the study was to investigate different treatment techniques to improve the sound radiation coefficient (R), which can be accomplished by reducing the density (ρ) and increasing or maintaining the dynamic Young modulus MOE Y . Treatments were tested on more easily available pine wood and successful treatments were repeated on high-value spruce tonewood. Fungal, heat and sodium treatment all improved R significantly. A combination of heat treatment with NaOH or fungal treatment resulted in the largest improvement in R. Unfortunately, the NaOH treatment could not be replicated on spruce, because it compromised the wood structure. Wood treatment in sodium solution to improve acoustic properties of tonewood were subsequently not regarded as feasible. Combined thermal and fungal (white rot) treatment showed the most promise and could successfully modify the acoustical properties of spruce with similar – although lower - results to pine. Thermal treatment improved in R in pine and spruce by 8.04% and 5.89%, respectively. White rot improved the R of pine by 3.98% after 6 weeks exposure and 11.05% after 20 weeks exposure. Experiments on spruce were repeated with a more practical time of 6 weeks exposure, which led to an increase in R of 0.31%. The combined heat/fungal treatment improved R in pine by 13.34%, while the combined heat/sodium treatment led to a ΔR of 19.83%. The combined heat/fungal treatment in spruce improved R by 5.45%. In all cases it could be shown that R increased, because the density was decreased without affecting the MOE Y negatively. This can be explained by the fact that the degraded components were predominantly hemicelluloses and extractives and the cellulose remained intact. Fungal- and sodium treatment have the additional effect of increasing the crystallinity of cellulose, as discussed above, which positively affects the MOE Y . For future work, it is suggested to identify a more suitable white rot to degrade spruce and increase spread and decay uniformity. Especially for tonewoods, it may be advisable to treat the wood shortly after harvesting and before seasoning. An alternative order of the combined treatments i.e., first heat treating the wood then submerging it in NaOH or subjecting it to fungal exposure could also be tested. DECLARATIONS Author Contribution K. Nefdt: performed all experimental work, interpreted and presented results, wrote first version of manuscriptM Meincken: Project conception and funding, guidance through experiments, substantial editing of manuscript Acknowledgement This work was supported by the National Research Foundation (NRF) through grant no. 141950. 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Research Square, pre-print, 1 -14 https://doi.org/10.21203/rs.3.rs-2188263/v1 Miao Y, Li R, Qian X, Yin Y, Yang Y, Jin X, Lin B, Liu Y, Liu Z (2021). Effect of extraction on the acoustic vibrational properties of Picea jezoensis var. microsperma (Lindl.). Annals of Forest Science, 78:1-13. https://doi.org/10.1007/s13595-021-01048-1 Nakano T (2010). Mechanism of microfibril contraction and anisotropic dimensional changes for cells in wood treated with aqueous NaOH solution. Cellulose, 17:711–719. https://doi.org/10.1007/s10570-010-9414-x Obataya E, Zeniya N, Endo-Ujiie K (2020). Effects of seasoning on the vibrational properties of wood for the soundboards of string instruments. The Journal of the Acoustical Society of America, 147:998–1005. https://doi.org/10.1121/10.0000723 Qi Y, Zhou Z, Xu R, Dong Y, Zhang Z, Liu M (2023). Effect of NaOH Pretreatment on Permeability and Surface Properties of Three Wood Species. ACS Omega, 8:40362–40374. https://doi.org/10.1021/acsomega.3c04745 Rang HY, Kang CW, Hong SH, Matsumura J (2016). Effect of heat treatment on the acoustic properties of a wooden xylophone keyboard. Journal of the Faculty of Agriculture, Kyushu University, 61:157–163. https://doi.org/10.5109/1564098 Rennenberg H, Schwarze FWMR, Gero Becker HC (2008). The application of wood decay fungi to improve the acoustical properties of resonance wood for violins. Available at: https://d-nb.info/98820701X/34 (Accessed: 06 June 2023). Rolleri M, Wentzel AA, Barros JL (2023). Vibroacoustic properties as a function of crystallinity changes in heat-treated Pinus radiata D. Don wood. Wood Material Science & Engineering, p 1–6. https://doi.org/10.1080/17480272.2023.2236960 Schelleng JC (1982). Wood for violins. Catgut Acoustical Society Newsletter, 37:8-19. Schwarze FWMR, Spycher M, Fink S (2008). Superior wood for violins - Wood decay fungi as a substitute for cold climate. New Phytologist, 179:1095–1104. https://doi.org/10.1111/j.1469-8137.2008.02524.x Su CK, Chen SY, Chung JH, Li GC, Brandmair B, Huthwelker T, Fulton JL, Borca C N, Huang SJ, Nagyvary J, Tseng HH, Chang CH, Chung DT, Vescovi R, Tsai YS, Cai W, Lu BJ, Xu JW, Hsu CS, Tai HC (2021). Materials Engineering of Violin Soundboards by Stradivari and Guarneri. Angewandte Chemie - International Edition, 60:19144–19154. https://doi.org/10.1002/anie.202105252 Taia HC, Lia GC, Huang SJ, Jhua CR, Chung JH, Wanga BY, Hsua CS, Brandmairc B, Chung DT, Chena HM, Chana JCC (2017). Chemical distinctions between Stradivari’s maple and modern tonewood. Proceedings of the National Academy of Sciences of the United States of America, 114:27–32. https://doi.org/10.1073/pnas.1611253114 Tumen I, Aydemir D, Gunduz G, Uner B, Cetin H (2010). Wood thermal treatment. BioResources, 5:1936 - 1944. Vybohova E, Kučerová V, Andor T, Balazova Z, Veľková V (2018). The Effect of Heat Treatment on the Chemical Composition of Ash Wood. BioResources, 13: 8394 - 8408. 10.15376/biores.13.4.8394-8408. Wachter I, Štefko T, Rolinec M (2019). Optimization of Two-Step Alkali Process of Lignin Removal from Basswood. Research Papers Faculty of Materials Science and Technology Slovak University of Technology, 27:153–161. https://doi.org/10.2478/rput-2019-0016 Wang D, Fu F, Lin L (2022). Molecular-level characterization of changes in the mechanical properties of wood in response to thermal treatment. Cellulose, 29:3131–3142. https://doi.org/10.1007/s10570-022-04471-3 Wang Z, Qu L, Qian J, He Z, Yi S (2019). Effects of the ultrasound-assisted pretreatments using borax and sodium hydroxide on the physicochemical properties of Chinese fir. Ultrasonics Sonochemistry, 50:200–207. https://doi.org/10.1016/j.ultsonch.2018.09.017 Xu E, Wang D, Lin L (2020). Chemical Structure and Mechanical Properties of Wood Cell Walls Treated with Acid and Alkali Solution. Forests, 11:87-98. 10.3390/f11010087. Xu H, Xu G, Wang L, Yu L (2014). Propagation behavior of acoustic wave in wood. Journal of Forestry Research, 25:671–676. https://doi.org/10.1007/s11676-014-0506-6 Yoshikawa S (2007). Acoustical classification of woods for string instruments. The Journal of the Acoustical Society of America, 122:568–573. https://doi.org/10.1121/1.2743162 Zatloukal P, Suchomelová P, Dömény J, Doskočil T, Manzo G, Tippner J (2021). Possibilities of decreasing hygroscopicity of resonance wood used in piano soundboards using thermal treatment. Applied Sciences, 11:1–10. https://doi.org/10.3390/app11020475 Zerbst D, Clauder L, Pfriem A (2018). Influence on acoustical properties of resonant soundboard material through different processes of thermal modification and treatments to increase reaction of wood to fire. European Conference on Wood Modification, Arnhem, Netherlands. Available at: https://www.researchgate.net/publication/328307582 (Accessed: 28 November 2022) Zhang SY, Fei BH, Wang CG (2016). Effects of chemical extraction treatments on nano-scale mechanical properties of the wood cell wall, BioResources, 11:7365-7376. Zhao Y, Wang Y, Zhu JY, Ragauskas A, Deng Y (2008). Enhanced enzymatic hydrolysis of spruce by alkaline pretreatment at low temperature. Biotechnology and Bioengineering, 99:1320–1328. https://doi.org/10.1002/bit.21712 Zhu L, Jiang T, Wu G (2017). Improvement of Acoustic-Vibration Performance of E. urophylla by High-Temperature Heat Treatment. Advances in Intelligent Systems Research, 154:148 – 153. https://doi.org/10.2991/icmia-17.2017.26 Zimmermann T, Richter K, Bordeanu N (2007). Arrangement of cell-wall constituents in chemically treated Norway Spruce tracheids. Wood and Fiber Science 39:221-231 Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4280659","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":292288731,"identity":"fa6b63d8-c06e-4790-a99a-f8500076a84e","order_by":0,"name":"Keenan Nefdt","email":"","orcid":"","institution":"Stellenbosch University","correspondingAuthor":false,"prefix":"","firstName":"Keenan","middleName":"","lastName":"Nefdt","suffix":""},{"id":292288732,"identity":"c1776d42-f666-4377-87de-505fc28c5826","order_by":1,"name":"Martina Meincken","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAArElEQVRIiWNgGAWjYJCCAwwVpGs5Q7I1jG2kqNaddvjg4cJ5dYnbGZgffmD4Y0dYi9nttITDM7cdTtzZwGYswcCTTIyWHIPDvNsOJG44wGDGwCDBTIyW/A+HeefUAbWwf2NgMKgnyhaGw7wNzEAtPEBbEg4T5ReDwzzHDhtvOMxTLJFw4DgxWpIff+apqZPdcLx944cPf6oJa0EAkMcTSNEwCkbBKBgFowA3AACtuTn6GejZ7QAAAABJRU5ErkJggg==","orcid":"","institution":"Stellenbosch University","correspondingAuthor":true,"prefix":"","firstName":"Martina","middleName":"","lastName":"Meincken","suffix":""}],"badges":[],"createdAt":"2024-04-17 08:57:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4280659/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4280659/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":55096096,"identity":"a7f2de99-6485-485a-a852-5428d88fa983","added_by":"auto","created_at":"2024-04-22 14:19:36","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":161246,"visible":true,"origin":"","legend":"\u003cp\u003eRelative change in R due to heat treatment as a function of exposure temperature for different exposure times for pine and spruce. Different letters indicate statistically significant differences\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4280659/v1/ce95e0a3031ba4f27fd8dab6.jpg"},{"id":55096099,"identity":"de9a3e33-2d01-4737-b992-2387cc5c6434","added_by":"auto","created_at":"2024-04-22 14:19:36","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":124065,"visible":true,"origin":"","legend":"\u003cp\u003eRelative change in R due to fungal degradation as a function of exposure time for pine and spruce. Different letters indicate statistically significant differences\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4280659/v1/9e075aadf4a9049c711393fc.jpg"},{"id":55096097,"identity":"8175047a-bf6c-409d-b532-11e869d3e30e","added_by":"auto","created_at":"2024-04-22 14:19:36","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":184250,"visible":true,"origin":"","legend":"\u003cp\u003eRelative change in R as a function of exposure time for sodium treatments.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4280659/v1/9a2731d2d035c6234642e85e.jpg"},{"id":55096098,"identity":"b5b17f6f-251a-4d0a-9c37-f811fbca8d4f","added_by":"auto","created_at":"2024-04-22 14:19:36","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":137634,"visible":true,"origin":"","legend":"\u003cp\u003ePenetration depth of NaOH into pine and spruce wood as a function of time. The insert shows a spruce wood block (as supplied from the luthier – the wedge shape is the starting dimension for the violin top plate)\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4280659/v1/2a7df5047cc3589a354bf688.jpg"},{"id":55265950,"identity":"95d3be4c-57b1-46ad-978b-9dde71f43961","added_by":"auto","created_at":"2024-04-25 02:16:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":757987,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4280659/v1/bd4afdef-2304-45cf-bb4c-88a162864eac.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Modifying the radiation ratio of tonewoods through wood degradation","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eFor centuries luthiers strived to enhance the sound quality of their musical instruments. Some copied the methods and techniques of their predecessors, while others tried new techniques, but the results were not always successful. This endeavour continues today as luthiers are trying to understand why some of the older instruments have a better sound quality. Most of those attempts were directed towards the violin.\u003c/p\u003e \u003cp\u003eWood used to manufacture instruments is referred to as tonewood, or resonance wood. The quality of the produced sound depends on the elastic properties of the wood and how well it can oscillate. The sound quality of tonewoods can be best described through the radiation ratio (R) which is defined as R = \u0026radic; MOE/ρ\u003csup\u003e3\u003c/sup\u003e. A significant difference can be observed between high- (15) - and low- (9) quality soundboards. Some of the famous Stradivari violins have R-values reaching 16 and above, whereas even the best quality modern violins tend to reach a maximum R of 12\u0026ndash;15. The reason that old instruments have a much higher R value can only be explained by partial wood degradation, which reduced the density, without affecting the MOE, or speed of sound, too much. Various attempts were made to improve the sound quality of wood through artificial ageing. The ones showing the most promise is heat treatment and fungal degradation (Danihelov\u0026aacute; et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Rang et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Zhu et al. 2016). Previous studies have shown that the most important wood characteristics for good sound quality are MOE \u0026ndash; which directly affects the speed of sound - and ρ (Zerbst et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). An increase in the MOE and lowering of ρ results in a higher R value. Soundboards easily transmit vibrations to the edges and are good sound radiators and typically have a low ρ and high MOE with a high sound radiation ratio and tend to resonate lower frequencies much clearer and louder than other wood species (Yoshikawa, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2007\u003c/span\u003e and 2014).\u003c/p\u003e \u003cp\u003eVarious attempts were made to improve the sound quality of wood through artificial ageing i.e., heat treatment and fungal degradation (Danihelov\u0026aacute; et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Rang et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Zhu et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Previous studies have shown that the most important wood characteristics for good sound quality are MOE \u0026ndash; which directly affects the speed of sound - and ρ (Zerbst et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). An increase in the MOE and lowering of ρ results in a higher R value.\u003c/p\u003e \u003cp\u003eIn previous studies it was observed that low and moderate thermal exposures (110\u0026deg;C\u0026ndash; 175\u0026deg;C) do not change acoustic properties significantly (Gadd and D\u0026rsquo;Arcy, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1986\u003c/span\u003e; Zerbst et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Thermal treatment between 160\u0026deg;C and 220\u0026deg;C was found most suitable to degrade hemicelluloses and lignin, as desired for acoustic changes (Esteves and Pereira, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; V\u0026yacute;bohov\u0026aacute; \u003cem\u003eet al.\u003c/em\u003e, 2018; Zerbst et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), because at these temperatures the desired density decrease is obtained. At temperatures above 250\u0026deg;C cellulose chains start to degrade, which then also affects the MOE. However, exposure to high temperatures for a short time may prove to be beneficial in improving the acoustic properties and was included in this experiment.\u003c/p\u003e \u003cp\u003eObataya (2017) studied the effect of artificial hydrothermal ageing on the acoustic properties of wood. Treatment between 1 and 7 days at a RH of 57\u0026ndash;64% was found to increase the specific dynamic Young modulus (E\u0026rsquo;/ρ) and decrease tan (δ), which indicates that heating at intermediate RH can improve the acoustical properties.\u003c/p\u003e \u003cp\u003eSchwarze et al. (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) discovered the presence of fungi, such as \u003cem\u003ePhysisporinus vitreus\u003c/em\u003e and \u003cem\u003eXylaria longpipes\u003c/em\u003e in the soundboard of old violins, which led to a decrease in hemicellulose content that might be responsible for the higher radiation ratio. Fungal degradation is a possible approach for the improvement of acoustical properties in wood, as the degradation of polysaccharides, such as hemicelluloses and lignin can have a positive effect on the acoustic properties. Fungi are known to deposit large amounts of organic acids as part of their natural metabolism that accumulate as oxalate salts along their hyphae. These salts form crystalline structures along the hyphae (Cromack et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e1977\u003c/span\u003e), which leads to an increase in c and MOE\u003csub\u003eL\u003c/sub\u003e. These findings suggest that extended incubation periods with fungi can improve c up to a point where degradation of the cell wall occurs. It can therefore be concluded that the appropriate fungus capable of secreting a large amount of oxalate salts will improve acoustic properties of wood.\u003c/p\u003e \u003cp\u003eWood degrading fungi are typically grouped into white rot and brown rot, depending on the wood components they attack. White rot fungi degrade cellulose, hemicellulose and lignin, while brown rot degrades only hemicellulose and cellulose. The main objective of this study was to decrease the wood density by removing hemicelluloses and part of the lignin, without compromising the strength provided by the cellulose. Therefore, the effect of degradation caused by both brown and white rot fungi was analysed.\u003c/p\u003e \u003cp\u003eNot much research exists dealing with chemical treatment of sodium hydroxide (NaOH) and sodium sulfite (Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003e) for improvement of acoustical wood properties. The selection of these two compounds for this study is based the fact that recent studies found high levels (1000 ppm) of Na and other elements (e.g., K, Cl, Ca, Cu and Zn etc.) residing in the cell wall structure of violins made from Stradivari and Guarneri (Taia et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Su et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). A further assumption is that timber companies made use of salt as preservative in the waterways used to move logs, which could have, at some point, had a positive implication on the chemical structure of musical instruments (Gug, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e1988\u003c/span\u003e). The above findings suggest that some minerals added via chemical or preservative treatment may have been used that improved the acoustical properties of historical musical instruments over time. Studies have found that alkaline treatment increases the crystallinity index of cellulose (Xu et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), which might result in improved acoustical properties.\u003c/p\u003e \u003cp\u003eBoth sodium compounds were found to reduce the density of wood by degrading hemicellulose and lignin, while leaving the cellulose intact (Wachter et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Li et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Compared to acids (i.e., H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e), alkaline solutions do not damage the S2-layer, but loosen the middle lamella, where the largest proportion of hemicellulose resides especially, if combined with thermal treatments of 100\u0026deg;C and 120\u0026deg;C. Moreover, the combination of the two compounds was found to degrade hemicellulose more effectively (Maturana et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Kim et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe benefits of an increased crystallinity index of the cellulose were shown to improve the acoustical properties of wood (Miao et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Wang et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). This implies that any substance capable of increasing the crystallinity in wood may have a beneficial impact on the vibro-acoustical properties of wood, as soundwaves can move more easily through a crystalline structure than amorphous materials. NaOH was found to improve the crystallinity index of cellulose by selectively removing amorphous hemicellulose (Qi et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Barman et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). However, alkaline treatments may decrease the crystallinity in wood at higher concentrations and longer exposure times (Xu et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Nakano, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe aim of this study is to modify and improve the acoustic properties of wood through various treatments: heat treatment, fungal exposure, UV exposure, sodium hydroxide (NaOH) and sodium sulphate (Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003e) treatment. These treatments are expected to decrease the hemicelluloses, lignin and extractive content and therefore the density of wood, without significantly altering the MOE and therefore improve R.\u003c/p\u003e"},{"header":"2.\tMATERIALS AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003e2.1 Wood\u003c/h2\u003e\n\u003cp\u003eRadially cut pine (\u003cem\u003ePinus patula\u003c/em\u003e) samples were used to determine the most suitable treatment, which was then repeated on tonewood spruce. The wood was cut from the sapwood part of boards originating from mature trees. Density, moisture content (MC) and the speed of sound (c) were measured before and after treatment. Sample sizes were 150 x 55 x 20mm for heat treatment, 60 x 20 x 15mm for fungal exposure, and 60 x 40 x 20mm for sodium, treatment. The sample sizes were different to accommodate the different exposure environments. For the sodium and fungal exposure samples smaller samples are required to ensure full saturation / coverage. All samples were stored for at least one month in a conditioning room at 65% RH and 20\u0026deg;C, before analysis and all measurements were performed at least in triplicate.\u003c/p\u003e\n\u003cp\u003eHigh quality spruce (\u003cem\u003ePicea abies\u003c/em\u003e) tonewood was obtained from a luthier in Pretoria, South Africa (Hannes Jacobs) and used to determine if the successful changes in acoustical properties of the optimum treatment could be transferred between wood species.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n\u003ch2\u003e2.2 Treatment methods\u003c/h2\u003e\n\u003cp\u003eThermal treatment was performed in an oven at temperatures of 160, 180, 200, 230 and 250 \u003csup\u003eo\u003c/sup\u003eC for times ranging from 5 minutes to several hours. For temperatures above 200\u0026deg;C, the wood blocks were wrapped in aluminum foil to prevent surface discolouration and charring. The experimental procedure was as follows: 160\u0026ndash;200\u0026deg;C for 1 to 8 h, 230\u0026deg;C for 10-, 30 min and 1 h and 250\u0026deg;C at 5-, 15-, 30 min and 1 h. The high temperatures were chosen to ensure that hemicellulose degradation took place.\u003c/p\u003e\n\u003cp\u003eSixteen samples were exposed to brown rot (\u003cem\u003eLaetiporius sulphurous\u003c/em\u003e) and white rot (\u003cem\u003eSchizophyllum commune\u003c/em\u003e), respectively. To keep the fungus alive, the samples were placed in closed plastic containers with paper towels, which were wetted on a weekly basis. To obtain a successful spread rate, separate pine samples were pre-exposed for 8 months to start the fungal activity. The pre-exposed samples were then placed together with the treatment samples and left for incubation of 1, 2, 6 and 20 weeks. Five samples were removed for each exposure time, the fungus was scraped off and the wood was carefully dried in an oven at 40\u0026deg;C for 24 h.\u003c/p\u003e\n\u003cp\u003eFor chemical treatment in saline solution, samples were fully submerged in NaOH and Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003e for 8, 24, 48, 72, 120 and 168 h. Four samples were removed for each exposure time and washed in distilled water for 24 h to remove any excess NaOH and Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003e, before drying in an oven at 100\u0026deg;C for 24 h. Samples were also exposed to a combined NaOH\u0026thinsp;+\u0026thinsp;Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003e solution for 8, 24, 48 and 72 h.\u003c/p\u003e\n\u003cp\u003eAfter treatment all samples were stored in a conditioning room for 2 weeks before measuring their acoustical properties to ensure that the physical changes are not just temporary. All measurements were performed at least in triplicate.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n\u003ch2\u003e2.3 Measurement of physical properties\u003c/h2\u003e\n\u003cp\u003eThe speed of sound (c) was determined with a Lucchi meter, which determines the time an ultrasound pulse requires to travel from the emitter to the receiver to determine c in m/s. C was measured along the grain at three different locations for each piece of wood. The length and MC of the wood need to be input into the instrument beforehand to obtain correct values for c. The average of the three measurements along each sample was used to calculate R.\u003c/p\u003e\n\u003cp\u003eTo determine the MC, 5 pieces were cut from each board and the MC determined with the equation:\u003c/p\u003e\n\u003cp\u003eMC (%)\u0026thinsp;=\u0026thinsp;100 * (m-m\u003csub\u003e0\u003c/sub\u003e)/m\u003c/p\u003e\n\u003cp\u003eThe density was determined before and after each treatment after conditioning the samples for 2 weeks at 20\u003csup\u003eo\u003c/sup\u003eC and 65% RH by weighing the sample and calculating the volume.\u003c/p\u003e\n\u003cp\u003eR was calculated according to its definition by Schelleng (\u003cspan class=\"CitationRef\"\u003e1982\u003c/span\u003e):\u003c/p\u003e\n\u003cp\u003eR\u0026thinsp;=\u0026thinsp;c / \u0026rho;\u003c/p\u003e\n\u003cp\u003eBucur (\u003cspan class=\"CitationRef\"\u003e1987\u003c/span\u003e) showed that the specific dynamic Young modulus (MOE/\u0026rho;) can be derived from ultrasonic speed of sound measurements and MOE\u003csub\u003eL\u003c/sub\u003e was accordingly determined by:\u003c/p\u003e\n\u003cp\u003eMOE\u003csub\u003eY\u003c/sub\u003e = c * \u0026rho;\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n\u003ch2\u003e2.4 Combined treatment approach\u003c/h2\u003e\n\u003cp\u003eThe treatments that showed the largest improvement in R - in this case treatment with white rot (\u003cem\u003eS. commune\u003c/em\u003e) and NaOH solution \u0026ndash; were combined with the heat treatment that had the largest improvement in R (one hour at 250\u0026deg;C).\u003c/p\u003e\n\u003cp\u003eThe most successful combined treatment was repeated on spruce tonewood, and the wood samples were prepared and treated in the same way as described above.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n\u003ch2\u003e2.5 Representation of results and statistical analysis\u003c/h2\u003e\n\u003cp\u003eThe distribution of data was checked for normality with the \u003cem\u003eShapiro-Wilk\u003c/em\u003e test. The statistical analysis result was determined through a \u003cem\u003eKruskal-Wallis\u003c/em\u003e test, followed by a post-hoc \u003cem\u003eDunn\u0026rsquo;s\u003c/em\u003e test to determine significant differences indicated by different letters. The significance level was p\u0026thinsp;=\u0026thinsp;0.05.\u003c/p\u003e\n\u003cp\u003eAll results are presented as average values with error bars depicting the standard deviation. All graphs were plotted with \u003cem\u003eOriginLab\u003c/em\u003e.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"3.\tRESULTS AND DISCUSSION ","content":"\u003cp\u003eThe following graphs show the change in R after treatment. A positive \u0026Delta;R correlates to an improved value of R, which means that the treatment was successful in decreasing the density without affecting the MOE considerably.\u003c/p\u003e\n\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1 Heat treatment\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e shows that lower exposure temperatures slightly reduced R, which is not desirable to improve the acoustic properties. Furthermore, the exposure time did not have any statistically significant effect on \u0026Delta;R for temperatures below 200 \u003csup\u003eo\u003c/sup\u003eC. However, the effect of exposure time on R becomes noticeable above 200\u0026deg;C with the largest difference between exposure times at 250\u0026deg;C. The largest improvement in R of 8% was obtained after exposure to 250\u0026deg;C for 1 h.\u003c/p\u003e\n \u003cp\u003eThe improvement in R can be linked to a decrease in \u0026rho; while maintaining or increasing MOE, as highlighted in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003eTable 1 changes in \u0026rho;, c, MOE\u003csub\u003eY\u003c/sub\u003e and R as function of the exposure temperature. Treatments that reduced \u0026rho; and maintained or improved MOE\u003csub\u003eY\u003c/sub\u003e are highlighted\u003c/p\u003e\n \u003ctable style=\"width:404.0pt;border-collapse:collapse;border:none;margin-left:6.75pt;margin-right:6.75pt;\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53.35pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 22.7pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-family:\"Times New Roman\",serif;color:black;'\u003eT (\u0026deg;C)\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54.25pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 22.7pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-family:\"Times New Roman\",serif;color:black;'\u003et (h)\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 22.7pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-family:\"Times New Roman\",serif;color:black;'\u003e\u0026Delta; \u0026rho;\u003csub\u003e\u0026nbsp;\u003c/sub\u003e(%)\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 22.7pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-family:\"Times New Roman\",serif;color:black;'\u003e\u0026Delta; c\u003csub\u003e\u0026nbsp;\u003c/sub\u003e(%)\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 22.7pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-family:\"Times New Roman\",serif;color:black;'\u003e\u0026Delta; MOE\u003csub\u003esd\u0026nbsp;\u003c/sub\u003e(%)\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 22.7pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-family:\"Times New Roman\",serif;color:black;'\u003e\u0026Delta; R\u003csub\u003e\u0026nbsp;\u003c/sub\u003e(%)\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" style=\"width: 53.35pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e160\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54.25pt;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid rgb(127, 127, 127);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e1\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid rgb(127, 127, 127);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.22 \u0026plusmn; 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0.55\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.71 \u0026plusmn; 4.07\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-6.86 \u0026plusmn; 4.30\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-0.64 \u0026plusmn; 3.63\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e8\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.53 \u0026plusmn; 1.74\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-2.84 \u0026plusmn; 1.38\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-7.01 \u0026plusmn; 3.58\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.31 \u0026plusmn; 1.85\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" style=\"width: 53.35pt;border-right: none;border-bottom: none;border-left: none;border-image: initial;border-top: 1pt solid rgb(127, 127, 127);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e180\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54.25pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e1\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.13 \u0026plusmn; 0.45\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.74 \u0026plusmn; 2.02\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-4.51 \u0026plusmn; 4.13\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-0.62 \u0026plusmn;1.86\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e3\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-0.87 \u0026plusmn; 0.88\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-3.02 \u0026plusmn; 1.22\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-6.75 \u0026plusmn; 2.64\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-2.16 \u0026plusmn; 1.38\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e6\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-2.34 \u0026plusmn; 1.16\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-3.63 \u0026plusmn; 0.98\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-9.28 \u0026plusmn; 2.71\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.32 \u0026plusmn; 0.82\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e8\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-2.25 \u0026plusmn; 0.23\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-3.28 \u0026plusmn; 0.80\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-8.56 \u0026plusmn; 1.43\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.05\u0026plusmn; 0.94\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" style=\"width: 53.35pt;border-right: none;border-bottom: none;border-left: none;border-image: initial;border-top: 1pt solid rgb(127, 127, 127);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e200\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54.25pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e1\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e0.01 \u0026plusmn; 0.52\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-5.60 \u0026plusmn; 2.33\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-10.84 \u0026plusmn; 4.21\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-5.60 \u0026plusmn; 2.59\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e3\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.04 \u0026plusmn; 1.43\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-4.44 \u0026plusmn; 2.38\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-9.56 \u0026plusmn; 5.25\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-3.44 \u0026plusmn; 2.02\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e6\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-2.44 \u0026plusmn; 1.59\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-5.54 \u0026plusmn; 3.26\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-12.81 \u0026plusmn; 7.21\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-3.20 \u0026plusmn; 2.23\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e8\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-2.57 \u0026plusmn; 0.73\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-5.74 \u0026plusmn; 2.17\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-13.37 \u0026plusmn; 4.53\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-3.26 \u0026plusmn; 1.67\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" style=\"width: 53.35pt;border-right: none;border-bottom: none;border-left: none;border-image: initial;border-top: 1pt solid rgb(127, 127, 127);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e230\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54.25pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e0.17\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-0.09 \u0026plusmn; 0.13\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-2.52 \u0026plusmn; 1.63\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-5.04 \u0026plusmn; 3.09\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-2.42 \u0026plusmn; 1.70\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e0.5\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.17 \u0026plusmn; 0.31\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-2.43 \u0026plusmn; 3.73\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-5.81 \u0026plusmn; 7.30\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.28 \u0026plusmn; 3.68\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e1\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-3.06 \u0026plusmn; 1.58\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e1.16 \u0026plusmn; 0.92\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-0.82 \u0026plusmn; 1.2\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e4.38 \u0026plusmn; 2.50\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border: none;background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e2.5\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border: none;background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-3.54 \u0026plusmn; 2.24\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border: none;background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e3.27 \u0026plusmn; 0.83\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border: none;background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e2.90 \u0026plusmn; 3.50\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border: none;background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e7.09 \u0026plusmn; 2.17\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" style=\"width: 53.35pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cstrong\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e250\u003c/span\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54.25pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-family:\"Times New Roman\",serif;color:black;'\u003e0.08\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e0.15 \u0026plusmn; 0.06\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-2.95 \u0026plusmn; 1.17\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-5.66 \u0026plusmn; 2.29\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-3.09 \u0026plusmn; 1.15\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-family:\"Times New Roman\",serif;color:black;'\u003e0.25\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e0.06 \u0026plusmn; 0.41\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.66 \u0026plusmn; 1.41\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-3.23 \u0026plusmn; 2.57\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-1.71 \u0026plusmn; 1.67\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-family:\"Times New Roman\",serif;color:black;'\u003e0.5\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e1.70 \u0026plusmn; 0.71\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e0.88 \u0026plusmn; 0.79\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e3.50 \u0026plusmn; 1.67\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: 1pt solid rgb(127, 127, 127);border-left: none;border-bottom: 1pt solid rgb(127, 127, 127);border-right: none;padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-0.81 \u0026plusmn; 1.11\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 54.25pt;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid rgb(127, 127, 127);background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-family:\"Times New Roman\",serif;color:black;'\u003e1\u0026nbsp;\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.9pt;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid rgb(127, 127, 127);background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e-4.46 \u0026plusmn; 0.88\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6pt;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid rgb(127, 127, 127);background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e3.21 \u0026plusmn; 0.43\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84.05pt;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid rgb(127, 127, 127);background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e1.77 \u0026plusmn; 1.17\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.85pt;border-top: none;border-right: none;border-left: none;border-image: initial;border-bottom: 1pt solid rgb(127, 127, 127);background: rgb(217, 217, 217);padding: 0in 5.4pt;height: 17pt;vertical-align: top;\"\u003e\n \u003cp style='margin:0in;font-size:16px;font-family:\"Calibri\",sans-serif;text-align:center;'\u003e\u003cspan style='font-size:15px;font-family:\"Times New Roman\",serif;color:black;'\u003e8.04 \u0026plusmn; 1.15\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003eDe Rolleri et al. (\u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e) report that an increase in exposure temperature and time improves MOE at temperatures above 120\u0026deg;C. However, statistical analysis of our results shows no significant difference for different exposure temperatures and times for temperatures below 200\u0026deg;C, which is similar to what was reported by several other authors (Kučerov\u0026aacute; et al., \u003cspan class=\"CitationRef\"\u003e2016\u003c/span\u003e; Kocaefe et al., \u003cspan class=\"CitationRef\"\u003e2008\u003c/span\u003e; Zhao et al., \u003cspan class=\"CitationRef\"\u003e2008\u003c/span\u003e; de Jesus et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e; Mania and Skrodzka, \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003eThe main cause for the increase in R is a reduction in density as extractives and hemicelluloses are removed as volatile components during thermal treatment, which results in a mass loss (Holeček et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e; Tumen et al., \u003cspan class=\"CitationRef\"\u003e2010\u003c/span\u003e; de Jesus et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e; Zatloukal et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e; Akg\u0026uuml;l et al., \u003cspan class=\"CitationRef\"\u003e2007\u003c/span\u003e; Wang et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e). The increase in MOE\u003csub\u003eY\u003c/sub\u003e is caused by the increased crystallisation of hemicellulose and cellulose, which was also found by other authors (de Jesus et al. \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e; Zatloukal et al. \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e; Akg\u0026uuml;l et al. \u003cspan class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003eThe best thermal treatment of 250\u0026deg;C for 1 h was repeated on spruce to ensure that the results can be translated between wood species. The increase in R was somewhat smaller for spruce than for pine, but with and average \u0026Delta;R\u0026thinsp;=\u0026thinsp;5.89% still noteworthy.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2 Fungal degradation\u003c/h2\u003e\n \u003cp\u003eWhite rot showed a much faster spread rate than the brown rot after 20 weeks of incubation and both brown (\u003cem\u003eL. sulphurous\u003c/em\u003e) and white rot (\u003cem\u003eS. commune\u003c/em\u003e) samples showed a significant reduction in \u0026rho; with an increase in exposure time, which translates into an increase in R, as can be seen in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003eThe changes in c, \u0026rho;, MOE\u003csub\u003eY\u003c/sub\u003e and R are highlighted in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e (brown rot) and 3 (white rot).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eThe average change in \u0026rho;, c, MOE\u003csub\u003eY\u003c/sub\u003e and R of pine incubated with brown rot (\u003cem\u003eL. sulphurous\u003c/em\u003e) with standard deviations\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003et (weeks)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta; \u0026rho; (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta; c (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta; MOE\u003csub\u003eL\u003c/sub\u003e (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta; R (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.73\u0026thinsp;\u0026plusmn;\u0026thinsp;1.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.61\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-1.17\u0026thinsp;\u0026plusmn;\u0026thinsp;1.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-2.81\u0026thinsp;\u0026plusmn;\u0026thinsp;3.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.65\u0026thinsp;\u0026plusmn;\u0026thinsp;1.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-1.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-1.01\u0026thinsp;\u0026plusmn;\u0026thinsp;0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.43\u0026thinsp;\u0026plusmn;\u0026thinsp;1.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10.06\u0026thinsp;\u0026plusmn;\u0026thinsp;3.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e6.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eThe average change in \u0026rho;, c, MOE\u003csub\u003eL\u003c/sub\u003e and R of pine incubated with white rot (\u003cem\u003eS. commune\u003c/em\u003e) with standard deviations.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003et (weeks)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta; \u0026rho; (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta; c (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta; MOE\u003csub\u003eL\u003c/sub\u003e (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta; R (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.02\u0026thinsp;\u0026plusmn;\u0026thinsp;1.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.69\u0026thinsp;\u0026plusmn;\u0026thinsp;2.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.41\u0026thinsp;\u0026plusmn;\u0026thinsp;1.26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-0.37\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.28\u0026thinsp;\u0026plusmn;\u0026thinsp;1.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.66\u0026thinsp;\u0026plusmn;\u0026thinsp;1.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-1.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.61\u0026thinsp;\u0026plusmn;\u0026thinsp;1.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.92\u0026thinsp;\u0026plusmn;\u0026thinsp;3.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.98\u0026thinsp;\u0026plusmn;\u0026thinsp;2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e-3.50\u0026thinsp;\u0026plusmn;\u0026thinsp;1.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e7.15\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10.79\u0026thinsp;\u0026plusmn;\u0026thinsp;3.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.05\u0026thinsp;\u0026plusmn;\u0026thinsp;2.81\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eAfter 20 weeks of exposure, brown and white rot reduced \u0026rho; by about 1% and 3.5%, respectively, which lead to an increase in R of about 6% and 11%. The treatment successfully reduced \u0026rho; without negatively affecting MOE, which allows the conclusion that the fungi degraded predominantly lignin and hemicelluloses without compromising cellulose.\u003c/p\u003e\n \u003cp\u003eThe results show that fungal degradation can indeed improve \u0026rho;. The density loss caused by the two fungi was similar, but brown rot had a slower spread rate compared white rot. Significant changes in \u0026rho;, MOE\u003csub\u003eY\u003c/sub\u003e and R occurred after an exposure time of 6 weeks, which was deemed to be a more feasible time to improve tonewood than 20 weeks. Therefore, the fungal treatment of spruce with to white rot was repeated with an exposure time of 6 weeks. Unfortunately, R in spruce increased only slightly by 0.31%, which is similar to what others have reported (Rennenberg et al., \u003cspan class=\"CitationRef\"\u003e2008\u003c/span\u003e). This indicates that degradation did take place in spruce to some degree and that longer exposure times may be needed to obtain a more significant reduction in density.\u003c/p\u003e\n \u003cp\u003eThe lower increase in R in spruce can be explained by the fact that the tonewood has been seasoned for a very long time and reached a very stable conformation, which made it more difficult for the fungi to penetrate the wood. Furthermore, \u003cem\u003eS. commune\u003c/em\u003e may not be the most suitable white rot fungus to decrease the density in spruce and another species may yield better results.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003e3.3 NaOH and Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003e treatments\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e highlights the changes in R after treatment with the two sodium solutions and a combination of both solutions. Generally, the NaOH solution had a more positive effect on R compared to the Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003e solution, or the combination.\u003c/p\u003e\n \u003cp\u003eInitially both the 0.2 M NaOH and Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003e solution significantly decreased R, which is undesirable. On average, the NaOH solution resulted in positive \u0026Delta;R values between 2 and 4% for all exposure times and independent of the concentration. The Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003e solution showed lower increases in R and no clear trend, which concentration yields better results. This shows clearly that a NaOH solution is more effective in improving R for exposure times up to about 160 h, after which \u0026Delta;R starts to decrease. It can be assumed that higher exposure times damage the cell wall structure, resulting in a decrease of structural integrity and therefore MOE and R.\u003c/p\u003e\n \u003cp\u003eThe density reduction was found to be significantly greater at higher concentration and longer exposure time for both sodium treatments. Zimmermann et al. (\u003cspan class=\"CitationRef\"\u003e2007\u003c/span\u003e) explained that increased NaOH concentration degrades hemicellulose, and that mannose is the most vulnerable to NaOH. This was confirmed by various other studies (Zhang et al. \u003cspan class=\"CitationRef\"\u003e2016\u003c/span\u003e, Zhao et al. \u003cspan class=\"CitationRef\"\u003e2008\u003c/span\u003e and Barman et al. \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003eUnfortunately, the sodium treatment could not be replicated on spruce, as it led to cracks and honeycombing in the wood after drying. This may be caused by the fact that the NaOH did not penetrate the spruce wood well \u0026ndash; probably because the wood was very well seasoned, which caused uneven drying after sodium treatment that led to cracking of the surface.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n \u003ch2\u003e3.4 Combined treatments\u003c/h2\u003e\n \u003cp\u003eThe most promising treatments to improve R were the fungal treatment with white rot for 6 weeks,\u0026nbsp;heat treatment at 250\u0026deg;C for 1 h and sodium treatment with 0.2 M NaOH treatment for 120 h. These were combined to see if the combination would improve R even further and heat treatment of 250\u0026deg;C for 1 h was applied to the samples previously exposed to fungal treatment and sodium treatment, respectively. Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e highlights the changes in R for pine and spruce for the combined treatments and the results from the best performing individual treatments.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eImprovement in R after heat-, fungal- and sodium treatment, as well as combined treatments\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWood Type\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTreatment\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eExposure time\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026Delta;R (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ewhite rot\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6 weeks\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.98\u0026thinsp;\u0026plusmn;\u0026thinsp;2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ewhite rot\u0026thinsp;+\u0026thinsp;heat\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6 weeks, 1 h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.34\u0026thinsp;\u0026plusmn;\u0026thinsp;2.80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.2 M NaOH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e120 h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.2 M NaOH\u0026thinsp;+\u0026thinsp;heat\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e120h, 1 h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19.83\u0026thinsp;\u0026plusmn;\u0026thinsp;2.36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSpruce\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ewhite rot\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6 weeks\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSpruce\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ewhite rot\u0026thinsp;+\u0026thinsp;heat\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6 weeks, 1 h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.45\u0026thinsp;\u0026plusmn;\u0026thinsp;3.13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSpruce\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.2 M NaOH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e120 h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN/A\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSpruce\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.2 M NaOH\u0026thinsp;+\u0026thinsp;heat\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e120 h, 1 h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN/A\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eThe combined fungal / heat treatment showed a significant increase in R of more than 10% in pine wood compared to fungal exposure alone, which is a significant improvement. In spruce the combination increased \u0026Delta;R from 0.3% for fungal treatment alone, to about 5.5%, which is also a good improvement.\u003c/p\u003e\n \u003cp\u003eThe combined sodium / heat treatment improved R in pine wood to about 20%, which is 14% more than the sodium treatment alone. This shows that sodium treatment followed by heat treatment is highly effective in improving the acoustic properties of pine wood.\u003c/p\u003e\n \u003cp\u003eThe combined sodium / heat treatment could unfortunately not be repeated on spruce, because the sodium solution compromised the wood structure and led to cracking and honey combing. This can probably be explained by the fact that the spruce wood has been well seasoned, which made penetration of the dry and stabilized wood very difficult.\u003c/p\u003e\n \u003cp\u003eThe penetration depth of pine and spruce was determined in a subsequent experiment on larger wood blocks. The penetration depth of the pine wood increased linearly with time, which means that the small sample blocks for the experiment were fully saturated after a few days. On the other hand the penetration depth in spruce remained around 5 mm over a measurement period of 18 days.\u003c/p\u003e\n \u003cp\u003eThe fact that the spruce wood is fairly impenetrable also explains why the fungal treatment of spruce was significantly less effective when compared to pine.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4.\tCONCLUSIONS","content":"\u003cp\u003eThe aim of the study was to investigate different treatment techniques to improve the sound radiation coefficient (R), which can be accomplished by reducing the density (ρ) and increasing or maintaining the dynamic Young modulus MOE\u003csub\u003eY\u003c/sub\u003e. Treatments were tested on more easily available pine wood and successful treatments were repeated on high-value spruce tonewood.\u003c/p\u003e \u003cp\u003eFungal, heat and sodium treatment all improved R significantly. A combination of heat treatment with NaOH or fungal treatment resulted in the largest improvement in R. Unfortunately, the NaOH treatment could not be replicated on spruce, because it compromised the wood structure. Wood treatment in sodium solution to improve acoustic properties of tonewood were subsequently not regarded as feasible. Combined thermal and fungal (white rot) treatment showed the most promise and could successfully modify the acoustical properties of spruce with similar \u0026ndash; although lower - results to pine. Thermal treatment improved in R in pine and spruce by 8.04% and 5.89%, respectively. White rot improved the R of pine by 3.98% after 6 weeks exposure and 11.05% after 20 weeks exposure. Experiments on spruce were repeated with a more practical time of 6 weeks exposure, which led to an increase in R of 0.31%. The combined heat/fungal treatment improved R in pine by 13.34%, while the combined heat/sodium treatment led to a ΔR of 19.83%. The combined heat/fungal treatment in spruce improved R by 5.45%.\u003c/p\u003e \u003cp\u003eIn all cases it could be shown that R increased, because the density was decreased without affecting the MOE\u003csub\u003eY\u003c/sub\u003e negatively. This can be explained by the fact that the degraded components were predominantly hemicelluloses and extractives and the cellulose remained intact. Fungal- and sodium treatment have the additional effect of increasing the crystallinity of cellulose, as discussed above, which positively affects the MOE\u003csub\u003eY\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003eFor future work, it is suggested to identify a more suitable white rot to degrade spruce and increase spread and decay uniformity. Especially for tonewoods, it may be advisable to treat the wood shortly after harvesting and before seasoning. An alternative order of the combined treatments i.e., first heat treating the wood then submerging it in NaOH or subjecting it to fungal exposure could also be tested.\u003c/p\u003e"},{"header":"DECLARATIONS","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eK. Nefdt: performed all experimental work, interpreted and presented results, wrote first version of manuscriptM Meincken: Project conception and funding, guidance through experiments, substantial editing of manuscript\u003c/p\u003e\n\u003ch2\u003eAcknowledgement\u003c/h2\u003e\n\u003cp\u003eThis work was supported by the National Research Foundation (NRF) through grant no. 141950. Fungi were supplied by the Department for Plant Pathology, Stellenbosch University.\u003c/p\u003e\n\u003ch2\u003eData availability\u003c/h2\u003e\n\u003cp\u003eall data is publicly available\u003c/p\u003e\n\u003ch2\u003eAuthor declarations\u003c/h2\u003e\n\u003cp\u003eNo conflicts of interest exist\u003c/p\u003e"},{"header":"REFERENCES","content":"\u003col\u003e\n\u003cli\u003eAkg\u0026uuml;l M, G\u0026uuml;m\u0026uuml;şkaya E, Korkut S (2007). Crystalline structure of heat-treated Scots pine [Pinus sylvestris L.] and Uludaǧ fir [Abies nordmanniana (Stev.) subsp. bornmuelleriana (Mattf.)] wood. Wood Science and Technology, 41:281\u0026ndash;289. https://doi.org/10.1007/s00226-006-0110-9\u003c/li\u003e\n\u003cli\u003eAydin TY (2020). Ultrasonic evaluation of time and temperature-dependent orthotropic compression properties of oak wood. 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Biotechnology and Bioengineering, 99:1320\u0026ndash;1328. https://doi.org/10.1002/bit.21712\u003c/li\u003e\n\u003cli\u003eZhu L, Jiang T, Wu G (2017). Improvement of Acoustic-Vibration Performance of E. urophylla by High-Temperature Heat Treatment. Advances in Intelligent Systems Research, 154:148 \u0026ndash; 153. https://doi.org/10.2991/icmia-17.2017.26\u003c/li\u003e\n\u003cli\u003eZimmermann T, Richter K, Bordeanu N (2007). Arrangement of cell-wall constituents in chemically treated Norway Spruce tracheids. Wood and Fiber Science 39:221-231\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"improved radiation ratio, wood degradation, heat treatment, fungal exposure, sodium treatment","lastPublishedDoi":"10.21203/rs.3.rs-4280659/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4280659/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis work investigates different wood modification techniques to modify the acoustical properties of tonewoods, in particular the sound radiation ratio (R). The treatments used were heat- and fungal exposure, as well as immersion into NaOH and Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e3\u003c/sub\u003e solution and a combination of the most successful treatments. All initial experiments were performed on pine (\u003cem\u003ePinus patula\u003c/em\u003e) due to cost factors, before replicating the best performing treatment on high quality spruce tonewood (\u003cem\u003ePicea abies\u003c/em\u003e). The main objective was to reduce the hemicellulose content without severely degrading cellulose, which results in a reduction of density, while maintaining, or even improving the elasticity (MOE\u003csub\u003eL\u003c/sub\u003e), which results in an increase of R. Overall, the combined heat-fungal and heat-sodium treatments performed best and increased R by up to 20%. Sodium treatment led to the best increases in R, but compromised the wood structure in spruce and the treatment protocol needs to be developed further. Consequently, the most successful wood treatment to improve acoustical properties was determined to be exposure to white rot combined with heat treatment.\u003c/p\u003e","manuscriptTitle":"Modifying the radiation ratio of tonewoods through wood degradation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-22 14:19:31","doi":"10.21203/rs.3.rs-4280659/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"387a6234-5184-4a58-a2a3-7e71a29df6fd","owner":[],"postedDate":"April 22nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-04-24T16:12:35+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-22 14:19:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4280659","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4280659","identity":"rs-4280659","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}