Treesearch

Conservation ethics and material shortages are stimulating interest in reusing wood products from demolished buildings and reusing entire buildings. As one of an anticipated series of reports coming from our research project titled, bNondestructive structural evaluation of wood floor systems in historic buildings,c this paper reports the results of determining the modulus of elasticity (MOE) of wood joists via static and vibration methods in both edgewise and flatwise orientations. Fifteen new southern pine joists (2-by 16- in. by 30 ft.) and nine joists (2- by 16- in. by 20 ft.) salvaged...

Wood [Indonesian pine (IP), Indonesian Jabon (IJ) and USA southern yellow pine (USP)] was either in situ polymerized with tributyltin acrylate (TBTA) or acetylated and then exposed to termite and fungal degradation both in laboratory tests and field exposure. The TBTA woods had an average weight percent gain (WPG) of 11% for IP, 12% for IJ, and 10% for USP. The acetylated woods had a WPG of 15-27% for IP, 16% for IJ, and 12-21% for USP. All levels of TBTA and acetylation treatments were effective against the brown-rot fungus Tyromyces palustris and the white-rot fungus Coriolus versicolor...

Disposal of preservative-treated waste wood is a growing problem worldwide. Bioprocessing the treated wood offers one approach to waste management under certain conditions. One goal is to use wood decay fungi to reduce the volume of waste with an easily managed system in a cost-effective manner. Wood decay fungi were obtained from culture collections in the Mycology Center and Biodeterioration research unit at the USDA-FS Forest Products Laboratory (FPL), Madison, Wisconsin, and from FPL field sites. The 95 isolates had originally been taken from at least 66 sites from around the United...

In this study, the effect of compression wood formation on the release rate of chromium, copper, and arsenic elements from red pine (Pinus resinosa Ait) was investigated. Wood blocks from red pine containing compression and normal wood portions were treated with a 1.0% CCA-C solution and were then allowed to fix at 23 * 2*C (74 * 4*F) for 0, 6, 24, 48, 96, 192, and 336 hours. After each fixation period, the blocks removed from the conditioning room were subjected to 336 hours of leaching. Less chromium and copper elements were released from the compression wood blocks. For chromium, the...

The finite difference approximation is applied to estimate the moisture-dependent diffusion coefficient by utilizing test data of isothermal moisture desorption in northern red oak (Quercus rubra). The test data contain moisture distributions at discrete locations across the thickness of specimens, which coincides with the radial direction of northern red oak, and at specified times. Also, the rate of moisture variation at each specified time and location must be known or correctly estimated. The functional form of the diffusion coefficient as well as the boundary conditions at the...

An idealized theoretical equation to calculate flexural stiffness using transverse vibration of a simply end-supported beam is being considered by the American Society of Testing and Materials (ASTM) Wood Committee D07 to determine lumber modulus of elasticity. This commentary provides the user a quantitative view of six factors that affect the accuracy of using the idealized theoretical equation, idealized assumptions, and idealized boundary conditions. The six factors that affect the calculation of the flexural modulus of elasticity are ranked in order of importance, and recommendations...

Conventional preservatives used to protect wood from insect and microbial damages are presently of major concern to human health and the environment. Finding alternative and economical preservatives has not been successful. Previous studies have shown that the resinous material extracted from the guayule plant (Parthenium argentatum, Gray) has both insect- and microbial- resistant properties. Unfortunately, it has not been accepted commercially because of the lack of an adequate supply of the raw material. However, the potential domestication of the guayule plant to produce hypoallergenic...

White-rotting basidiomycetes do not colonize on southern yellow pine. This study seeks to reduce the resinous extractive content of southern yellow pine by treating it with blue stain fungi. The mycelial growth of wood-inhabiting ligninolytic white-rot fungi can be achieved on pretreated southern yellow pine wood. Aureobasidium, Ceratocystis, and Ophiostoma spp. removed 70% to 100% of the extractives from the southern yellow pine wood within a period of 3 to 6 days. Griofora fondosa, Hericium erinaceus, and Pleurotus ostreatus colonized readily after the treatment. As a result, ligninolytic...

Timber rivets, fasteners for glulam and heavy timber construction, have been used in Canada for about thirty years and recently were adopted by the U.S. National Design Specification for Wood Construction (NDS). Rivet connections can exhibit two failure modes, one of which is fundamentally different from those of other dowel fasteners. Failure can occur when a volume of wood bounded by the perimeter of the closely spaced rivets pulls out from the timber, or via a combination of fastener yielding and localized wood crushing. The code-sanctioned analysis of the wood failure mode for timber...

Analysis of complex gene families in the lignin-degrading basidiomycete Phanerochaete chrysosporium has been hampered by the dikaryotic nuclear condition. To facilitate genetic investigations in P. chrysosporium strain BRM-F-1767, we isolated a homokaryon from regenerated protoplasts. The nuclear condition was established by PCR amplification of five unlinked genes followed by probing with allele-specific oligonucleotides. Under standard nitrogen-limited culture conditions, lignin peroxidase, manganese peroxidase, and glyoxal oxidase activities of the homokaryon were equivalent to those of...