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Flexural properties of visually graded southern pine structural lumber were evaluated. Several grade controlling characteristics were considered relative to bending properties and compared with current design values. A total of 751 southern pine lumber specimens were obtained from a broad spectrum of regions in the southeastern United States. Visually graded No. 2, nominally two inch thick specimens, in four and six inch widths, were obtained from commercial sawmills. All specimens were evaluated by a certified grader in the laboratory. Actual dimensions, weight, and moisture content (MC) were measured. Growth and manufacturing related characteristics were identified and classified into two categories: strength reducing characteristics (SRC) and grade reducing characteristics (GRC). Specific gravity (SG), bending modulus of elasticity (MOE), and modulus of rupture (MOR), were determined for each specimen. The presence of knots was identified as the most significant SRC; their presence had the most significant impact on SG, MOE and MOR. For GRC, specimens with knots, warp and specimens that fell into the category none, were significantly lower in SG, MOE and MOR. MOE and the allowable design bending strength values yielded in this study met the current design value criteria for both widths tested. [ABSTRACT FROM AUTHOR]

In studies on Polish pine wood, the parameters determining its usefulness for processing are highly variable. In contrast, international studies on the optimum utilization of coniferous sawn wood describes its visual features as those indicating the distribution of defects and their impact on the selected mechanical and physical properties of sawn wood. Knottiness is one of the qualitative properties of sawn wood that is essential for wood grading. The objective of this study was to determine a correlation between variable knots and their soundness on the one hand and their selected strength parameters on the other. One of the basic issues of this work includes structural timber optimization. For Polish sawn wood, these indicators are still relatively new. The study material involved edged butt-end log lumber from a 120-year-old forest stand. The results confirmed a correlation between knots frequency and modulus of elasticity. The correlation was strong, indicating that sound knots play a major role in the process of the strength assessments. The study did not demonstrate a significant share of rotten knots and their effect on strength. [ABSTRACT FROM AUTHOR]

Increasing demand for resonance spruce has led to gradual depletion of resources in traditional areas. Consequently, to meet the need for raw material to manufacture musical instruments, sorting has become the key operation of exploitation. This study was completed on the largest Romanian resonance wood resource, to maximize outputs of flitches for violin, cello, and double bass instruments by optimizing traditional requirements regarding quality of raw material with its current level. Ten resonance spruces were felled and gradually turned into semi-manufactured musical instruments. The material was analysed for defects in all stages of conversion. The frequency of zero defective samples was 60%. Evolution of defects along the trees indicated the tree section from 1 m to 12 m above the ground for musical instruments manufacturing. Output in terms of flitches ranged from one tree to another: between 19 and 32% if calculated from logs volume, and between 13 and 30% if calculated from volume of the standing trees. The results advocated for relaxing traditional requirements on resonance logs, at least regarding buttress and knottiness. Thus, recommendations are made, from the perspective of increasing efficiency, on the admissibility of defects and size diversification of musical instruments. [ABSTRACT FROM AUTHOR]

Acoustic tomography is based on the velocity variation inside the inspected element. However, wood is heterogeneous and anisotropic, which causes natural velocity variations. In wood, the great challenge to apply this technology is to interpret and differentiate the natural variations of the material from those caused by deterioration. This study aimed to evaluate the interference caused by knots, the wave propagation direction, and the effect of juvenile and reaction wood on the velocities determined via ultrasonic tomography. The tests were performed using 40 disks of Pinus elliottii. From the results it was concluded that intrinsic orthotropy of the wood was reflected in the wave propagation on the disks with radial velocities greater than the tangential ones, higher velocities in the knot zones, and different velocities in the zones of compression and opposition wood. In the measurements using the diffraction mesh, the edge velocities (tangential direction with the maximum angle from the radial direction) were always lower than all of the other velocities in the disk. More significant variations in the velocity were obtained in the juvenile wood. These results contribute to quantifying some interferences associated with tomography images, such that the misinterpretation can be minimized. [ABSTRACT FROM AUTHOR]

This work compares the effectiveness of local reinforcements of pine beams. Test beams were reinforced with carbon fiber reinforced polymer (CFRP) tape and layered laminate bamboo composite (LLBC) plates. The effective length of local reinforcement reached 5% of the entire beam length. Beams were tested to determine static bending strength in accordance with the EN-408 (2012) standard. On the basis of testing and calculations, it was concluded that local reinforcement with both reinforcing materials caused a significant (p < 0.05) gain in load capacity and modulus of elasticity. The LLBC, which has a tensile strength 25 times lower and a modulus of elasticity 17 times lower than CFRP, resulted in the highest load capacity. This phenomenon is related to the more uniform stress distribution on the composite with LLBC plate - glue bond - wood layers and lower strain within the bond in comparison to the CFRP reinforcement. Therefore, critical stresses within the bond were not exceeded, which often happens in reinforcement with materials of high modulus of elasticity (such as CFRP tape).

Active anti-microbial effects of larch (Larix decidua Mill.) and pine (Pinus sylvestris L.) wood materials on Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecium, and Bacillus subtilis were tested. The agar-diffusion test, a method used in routine diagnostics, was implemented to detect anti-microbial effects of wooden discs and filter paper discs containing methanol extracts of different wood parts. The results showed that the bark of larch had an inhibitory effect on Staphylococcus aureus, and the heart wood of pine showed a significant anti-microbial effect on the gram-positive bacteria tested (Staphylococcus aureus, Enterococcus faecium, and Bacillus subtilis). These results were confirmed by using methanol-extracts. An anti-microbial activity against Pseudomonas aeruginosa was not found. Anti-bacterial effects of other parts of larch wood and of pine sapwood were also not found. The results of this study showed for the first time that certain parts of wood contain compounds that directly reduce microbial growth. These data are a further demonstration of the positive effects of specific wood species and could promote the usage of wood in hygienically sensitive areas.

Knot rejects obtained from pulp screening after sulphite pulping are difficult to dewater, which makes landfilling expensive and burning inefficient. The rejects were found to contain up to 50% cellulose, which is very susceptible to enzymatic hydrolysis to glucose. Knot rejects were hydrolyzed at 20% consistency in a laboratory peg mixer with cellulase enzyme. The thick slurry was liquefied within the first hour of mixing and resulted in a glucose concentration of over 100 g/L after 24 hours of reaction. This solution was fermented by yeast to give an ethanol concentration of over 5%. The laboratory results were confirmed at pilot scale with a mortar mixer (high consistency) or stirred tank reactor (medium consistency) at the 400 L and 6000 L scales, respectively. It was found that washing the knots with ammonia resulted in increased glucose conversion. Enzyme costs could be lowered by separating the enzyme from the hydrolyzed sugars by membrane ultrafiltration and recycling the enzyme to the subsequent batch of substrate. The combination of high-consistency hydrolysis and enzyme recycling minimizes capital investment, energy requirements, and enzyme costs, which are significant factors in the overall economic viability of cellulose conversion to ethanol.

This work compares the effectiveness of local reinforcements of pine beams. Test beams were reinforced with carbon fiber reinforced polymer (CFRP) tape and layered laminate bamboo composite (LLBC) plates. The effective length of local reinforcement reached 5% of the entire beam length. Beams were tested to determine static bending strength in accordance with the EN-408 (2012) standard. On the basis of testing and calculations, it was concluded that local reinforcement with both reinforcing materials caused a significant (p < 0.05) gain in load capacity and modulus of elasticity. The LLBC, which has a tensile strength 25 times lower and a modulus of elasticity 17 times lower than CFRP, resulted in the highest load capacity. This phenomenon is related to the more uniform stress distribution on the composite with LLBC plate - glue bond - wood layers and lower strain within the bond in comparison to the CFRP reinforcement. Therefore, critical stresses within the bond were not exceeded, which often happens in reinforcement with materials of high modulus of elasticity (such as CFRP tape). [ABSTRACT FROM AUTHOR]

Active anti-microbial effects of larch (Larix decidua Mill.) and pine (Pinus sylvestris L.) wood materials on Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecium, and Bacillus subtilis were tested. The agar-diffusion test, a method used in routine diagnostics, was implemented to detect anti-microbial effects of wooden discs and filter paper discs containing methanol extracts of different wood parts. The results showed that the bark of larch had an inhibitory effect on Staphylococcus aureus, and the heart wood of pine showed a significant anti-microbial effect on the gram-positive bacteria tested (Staphylococcus aureus, Enterococcus faecium, and Bacillus subtilis). These results were confirmed by using methanol-extracts. An antimicrobial activity against Pseudomonas aeruginosa was not found. Antibacterial effects of other parts of larch wood and of pine sapwood were also not found. The results of this study showed for the first time that certain parts of wood contain compounds that directly reduce microbial growth. These data are a further demonstration of the positive effects of specific wood species and could promote the usage of wood in hygienically sensitive areas. [ABSTRACT FROM AUTHOR]