Treesearch

The mechanisms underlying ethanol and heat tolerance are complex. Many different genes are involved, and the exact basis is not fully understood. The integrity of cytoplasmic and mitochondrial membranes is critical to maintain proton gradients for metabolic energy and nutrient uptake. Heat and ethanol stress adversely affect membrane integrity. These factors are particularly detrimental to xylose-fermenting yeasts because they require oxygen for biosynthesis of essential cell membrane and nucleic acid constituents, and they depend on respiration for the generation of ATP. Physiological...

Incised and non-incised Douglas-fir, western hemlock, and ponderosa pine L- joints were treated with ammoniacal-based pentachlorophenol, chromated zinc chloride, thiocyanomethylthiobenzothiazole (TCMBT) or TCMTB plus methylenebisthiocyanate or 3 iodo-2-propynyl carbamate with or without chlorpyrifos to retentions between 0.8 and 6.4 kg/m3 and exposed, uncoated, above ground on a test fence located in Corvallis, Oregon. Additional joints dipped in solutionsof zinc naphthenate were similarly exposed. Wood condition was assessed annually over a 12 year period. As expected, untreated ponderosa...

Under pure shear loading, an off-axis element of orthotropic material such as pure wood undergoes both shear and normal deformations. The ratio of the shear strain to a normal strain is defined as the shear coupling coefficient associated with the direction of the normal strain. The effects of shear coupling on shear properties of wood as predicted by the orthotropic elasticity theory were validated using our recently developed shear test fixture. The validation also serves to demonstrate that the shear test fixture possesses the capability to introduce a state of pure shear to the...

To evaluate the dimensional stability of phosphoramide-reacted wood, wood was reacted with a mixture which was derived from compounding phosphorus pentoxide and each of 12 amines including alkyl, halophenyl, and phenyl amines in N,N-dimethylformamide. Dimensional stability of such reacted wood was analyzed by antishrink efficiency (ASE) using the water-soak method. Volumetric swelling and equilibrium moisture content (EMC) of phosphoramide-reacted woods were also determined after being maintained at 27*C and 30% RH, 27*C and 65% RH, and 27oC and 90% RH for 21 d. The results revealed that...

The durability of preservative-treated stakes of second-growth Coastal Douglas-fir was evaluated in a field plot in northern Queensland, Australia. Results from this field trial indicate that second-growth Douglas-fir can be treated with preservatives to meet Australian standards and will provide long-term durability in adverse environments. Data presented indicate that within a 5-year time frame, the importance of minimum penetration parameters decreases as retention increases.

Published data on estimated air drying times of lumber are of limited usefulness because they are restricted to a specific location or to the time of year the lumber is stacked for drying. At best, these estimates give a wide range of possible times over a broad range of possible locations and stacking dates. This report describes a method for estimating air drying times for specific locations by optimizing a drying simulation using existing experimental air drying times for northern red oak, sugar maple, American beech, yellowpoplar, ponderosa pine, and Douglas-fir. The results are...

In recent years, the performance of copper naphthenate as a wood preservative has been in question. To understand the varying results of copper naphthenate in preventing wood decay, a closer look at eight naphthenic acid (NA) supplies was undertaken. Initial studies of NA samples from individual suppliers revealed large differences in chemical composition and wood preservation ability. Samples were rated from best to worst determined by percent weight loss due to fungal activity. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that one of the intermediate quality wood...

Chemical data pertinent to most-recently developed POM delignification systems will be presented. These data will be used to demonstrate the fundamental basis for the stability, self-buffering properties, versatility and high selectivity of these systems when used in combination with oxygen to convert native or residual lignin in wood or wood-pulp fibers to CO2 and H2O.

This paper has been prepared in order to discuss Fiber Loading™ for lightweight, high-opacity bible paper. Incorporating fillers within pulp fibers has been subject to research since 1960 (Green et al. 1962, Scallan et al. 1985, Allen et al. 1992). Fiber Loading™ is a method for manufacturing precipitated calcium carbonate (PCC) directly within the pulp processing system. The Fiber Loading™ process results in fiber loaded precipitated calcium carbonate (FLPCC™) being partly deposited both within the fiber on the fiber walls and in between the fibers, targeting replacement of cellulose...

Low-grade wastepapers and paper mill sludges can be extruded to form composite materials that can be used like fiberboard and hardboard.