Treesearch

Wood products are quite durable if exposure to moisture is minimized; however, most uses of wood involve considerable exposure to moisture. To preserve the wood, chemicals are used to minimize moisture pickup, to prevent insect attack, and/or to resist microbial growth. The chemicals used as preservatives can interfere with adhesive bonds to wood. Given the many potential modes of failures and of interference with bond formation by treatment chemicals, a way to systematically analyze the problem is needed. With the use of several tests, the source of the problem can be generally identified;...

Light-induced yellowing of lignocellulosicmaterials has been studied using 13C-enriched DHP (dehydrogenation polymer), selectively 13C-enriched at positions 1, 3, 4, and 5 in the aromatic ring, and quantitative solution state 13C NMR spectroscopy. The NMR study confirmed the results of previous studies using side-chain labeled DHP, mainly that coniferyl alcohol end groups are degraded with the subsequent formation of a- carbonylic structures, e.g. vanillin end groups. The developed technique renders the potential to follow chemical changes of aromatic carbons 1, 3, 4, and 5, independently...

This review provides an overview of the physiology and genetics of lignin degradation by white rot basidiomycetes. Emphasis is on recent advances and the reader is referred to earlier comprehensive reviews for historical perspective and background (Kirk and Farrell 1987; Gold and Alic 1993; Higuchi 1993; Cullen and Kersten 1996; Cullen 1997). Recent completion of a draft genome sequence has established P. chrysosporium as the premier model system, and our review therefore concentrates on this species. Other wood decay fungi are only occasionally mentioned. Areas of uncertainty are highlighted.

The world population has surpassed the 6 billion mark and many of these people live in rapidly developing countries that are and will continue to place increasing pressure on the world's natural fiber resources. The total demand for raw material from the forest for housing, packaging, and for office and home furnishings, to name a few; are increasing. Traditional solid lumber products will not be able to fully supply all these needs. Potential replacements include wood composites, plastics, and metals. In the wood composites arena, the tree resource is shrinking, so lower quality and...

Roof (attic and cathedral ceiling) and crawlspace ventilation has commonly been used as a moisture management tool to minimize performance problems associated with excessive moisture accumulation in these spaces. However, for homes located in the urban wildland interface, roof vents in particular provide an entry point into the attic for flame and burning embers. Research conducted at the University of California Fire Research Laboratory have shown that all forms of vents on the underside of the eaves (strip vents, frieze block, etc.), in both boxed and open-eave construction, are almost...

Environmentally acceptable mold inhibitors are needed to curb the growth of mold fungi in woodframe housing when moisture management measures fail. Excess indoor moisture can lead to rapid mold establishment which, in turn, can have deleterious affects on indoor air quality. Compounds with known mold inhibitory properties and low mammalian toxicity, such as food preservatives, pharmaceuticals, agricultural fungicides, wood preservatives, or plant extractives were evaluated individually and in combination for their ability to inhibit three common mold fungi on wood-based building materials....

On December 3 1, 2003, the wood preservation industry, in conjunction with the Environmental Protection Agency, voluntarily phased out the use of chromated copper arsenate (CCA)-treated lumber for residential applications. This ended over 25 years of CCA as the predominant wood preservative in the United States. The first generation of replacement preservatives, alkaline copper quats (ACQ) and copper azole (CA), has begun to replace CCA in 2004. Other potential replacements for CCA are under investigation at the Forest Products Laboratory (FPL). One of these, recently mandated by the 108th...

This publication discusses basic marketing and economic concepts, planning approach, and feasibility methodology for assessing log sort yard operations. Special attention is given to sorting small diameter and underutilized logs from forest restoration, fuels reduction, and thinning operations. A planned programming approach of objectively determining the feasibility of establishing a log sort yard operation is recommended. This critical thinking will help develop the strategic, marketing, business, and operational plans to guide the development and operation of the log sort yard. Prelimina...

The colloidal stickies which build up in mill process water during pulping are problematic and difficult to remove. The USDA Forestry Service examined precipitated calcium carbonate (PCC) as a means to ameliorate process water stickies, comparing: i) the effectiveness of PCC added directly into a slurry of deinked pulp with ii) in situ precipitation of PCC by the fibre loading method. It was found that without retention aids, fibre loaded PCC resulted in the greatest attraction of colloidal stickies to pulp - following the high-consistency refining required for fibre loading. Also, without...

The anisotropy of wood creates a complex problem for solving heat and mass transfer problems that require analyses be based on fundamental material properties of the wood structure. Most heat transfer models use average thermal properties across either the radial or tangential directions and have not differentiated the effects of cellular alignment, earlywood/latewood differentiation, ring orientation, and moisture content. Two 2-Dimensional finite element models have been developed that take these parameters into consideration. The first model is used to determine the effective thermal...