Treesearch

A collection of Mycena epipterygia from montane cloud forest in the Dominican Republic was found to have one-fourth to one-half monosporous basidia mixed with bisporous basidia. It is described as a new variety, M. epipterygia var. domingensis Lodge, differing from M. epipterygia var. epipterygioides and other two-spored varieties in having smaller dimensions of spores from bisporous basidia and an abundance of monosporous basidia, as well as differences in ecology and macro- and other microscopic characters. An additional member of sect. Hygrocyboideae, Mycena griseoviridis, was found to...

Large amounts of woody residues and wood waste are generated annually in the United States. In 2002, an estimated 240 million metric tons was generated during the extraction of timber from the Nation’s forests, from forestry cultural operations, in the conversion of forest land to nonforest uses, in the initial processing of roundwood timber into usable products, in the construction and demolition of buildings and structures, and in the manufacture, use, and disposal of solid wood products. Much of this material is indeed waste, but increasingly large shares are becoming valuable resources....

To restore and maintain ecosystem health and function in the western interior of the United States, many small-diameter stems need to be removed from densely stocked stands. These stems are considered nonusable or underutilized (good, economical uses need to be developed). As of now, the most logical use for the small-diameter resource is pulp. In this study, thermomechanical pulps (TMP) were prepared and evaluated from lodgepole pine submerchantable logs, utilizing different preparation procedures to show that mechanical pulping is a viable option for utilizing this small-diameter...

Equations for a two-dimensional finite difference heat flow analysis were developed and applied to ponderosa pine and Douglas-fir square timbers to calculate the time required to heat the center of the squares to target temperature. The squares were solid piled, which made their surfaces inaccessible to the heating air, and thus surface temperatures failed to attain the temperature of the heating air. The surface temperatures were monitored during heating and related to time by an empirical equation. When this equation was used as the boundary condition in the finite difference solution,...

The use of wood-derived fillers by the thermoplastic industry has been growing, fueled in part by the use of wood-fiber–thermoplastic composites by the construction industry. As a result, the durability of wood-fiber– thermoplastic composites after ultraviolet exposure has become a concern. Samples of 100% high-density polyethylene (HDPE) and HDPE filled with 50% wood-flour (WF) were weathered in a xenon arc-type accelerated weathering apparatus for 2000 h. Changes in surface chemistry were studied using spectroscopic techniques. X-ray photoelectron spectroscopy (XPS) was used to verify...

Recent studies on nondestructive evaluation (NDE) of logs have shown that a longitudinal stress-wave method can be used to nondestructively evaluate the modulus of elasticity (MOE) of logs. A strong relationship has been found between stress-wave MOE and static MOE of logs, but a significant deviation was observed between stress-wave and static values. The objective of this study was to investigate the effect of log diameter on stress-wave evaluation of MOE of logs and to develop a new stress-wave model by relating stress-wave MOE to log diameter for static MOE prediction. A total of 201...

For over 10 years, the Forest Products Laboratory has been monitoring the temperature histories of roof sheathing, roof rafters, and unventilated attics in outdoor attic structures that simulate typical light-framed construction. This report briefly summarizes findings from the roof temperature assessment project on black and white fiberglass shingles conducted from 1991 to 2001. Temperature histories are then presented for roof assemblies made with western redcedar (WRC), wood-thermoplastic composite (WTPC), and black and white fiberglass shingles and exposed in Madison, Wisconsin, from...

Laminated wood composites have been used widely in the secondary manufacturing processes in the wood panel industries. Warping, which is defined as the out-of-plane deformation of an initially flat panel, is a longstanding problem associated with the use of laminated wood composites. The mechanism of warping is still not fully understood. A new two- dimensional warping model based on mechanics of layered composites was introduced to simulate the warping behavior of laminated wood composites. Actual warping performances of veneered particleboard panels under different relative humidity...

This paper reports on the physical and mechanical properties and decay and termite resistance of fiberboard panels made from pine and beech treated with N’-N-(1, 8-Naphthalyl) hydroxylamine sodium salt(NHA-Na), borax, and boric acid at varying loadings. The panels were manufactured using 10 percent urea-formaldehyde resin and 1 percent NH4Cl. Mechanical and physical tests demonstrated no statistically significant reduction in modulus of rupture of specimens treated with borax +NHA-Na compared to untreated control specimens. Similar results were obtained for modulus of elasticity for all...

Native strains of Saccharomyces cerevisiae do not assimilate xylose. S. cerevisiae engineered for D-xylose utilization through the heterologous expression of genes for aldose reductase ( XYL1), xylitol dehydrogenase (XYL2), and D-xylulokinase ( XYL3 or XKS1) produce only limited amounts of ethanol in xylose medium. In recombinant S. cerevisiae expressing XYL1, XYL2, and XYL3, mRNA transcript levels for glycolytic, fermentative, and pentose phosphate enzymes did not change significantly on glucose or xylose under aeration or oxygen limitation. However, expression of genes encoding the...