Treesearch

For general linear models with normally distributed random errors, the probability of a Type II error decreases exponentially as a function of sample size. This potentially rapid decline reemphasizes the importance of performing power calculations.

A thin, solid, circular wood disk, cut from the transverse plane of a tree stem, can be modeled as a cylindrically orthotropic elastic material. It is known that a stress singularity can occur at the center of a cylindrically orthotropic disk subjected to uniform pressure. If a solid cylindrically orthotropic disk is subjected to sinusoidal pressure distributions, then other stress singularities can also occur in the disk. The criterion for the existence of these singularities is based on a simple relationship between two dimensionless elastic constant parameters and the sinusoidal...

The complete genome sequence of the ethanol-producing bacterium Zymomonas mobilis provides new opportunities for industrial alcohol fermentation.

To comply with the U.S. Environmental Protection Agency's "Cluster Rule," most U.S. mills have switched from the use of chlorine to chlorine dioxide as the oxidant in the first stage of bleaching. This process change has a downside. it increases the formation of mineral scale in bleach plants. Typically, calcium oxalate forms in the chlorine dioxide stages and calcium carbonate in the extraction stages. Many mills have directly linked significant production losses, increased maintenance costs, and increased bleach chemical costs to calcium-based scale formation.

This chapter represents a summary review and an update of an earlier discussion of the phenomenology of cellulose, together with an overview of recent developments in the chemistry of cellulose. Rather than attempting to integrate the discussions, they will be presented in two separate sections. Part A, by R.H. Atalla, deals with the states of aggregation of celluloses and key structural issues, particularly those with questions of structure still outstanding. Part B, by A. Isogai, presents an overview of recent developments in the chemistry of cellulose, both basic and applied. To...

A composite can be defined as two or more elements held together by a matrix. By this definition, what we call “solid wood” is a composite. Solid wood is a three-dimensional composite composed of cellulose, hemicelluloses and lignin (with smaller amounts of inorganics and extractives), held together by a lignin matrix. The advantages of developing wood composites are (1) to use smaller trees, (2) to use waste wood from other processing, (3) to remove defects, (4) to create more uniform components, (5) to develop composites that are stronger than the original solid wood, and (6) to be able...

The degradation of a wood load-bearing (in-service) member may be caused by any one of several organisms that derive their nourishment or shelter from the wood substrate in which they live. Consequently, it is important to periodically inspect wood structures to determine their condition. A comprehensive manual on the inspection of wood structural elements.

Wood specimens were coated with sol-gel deposits of aluminum isopropoxide, titanium isopropoxide, or zirconium propoxide in the presence of methytrimethoxysilane. Both zirconium propoxide and titanium isopropoxide sol-gel deposits reduced water sorption, whereas aluminum isopropoxide sol-gel deposit increased water sorption, compared with uncoated wood specimens. There differences may be ascribed to differences in the distribution a/ the sol-gel deposits within the surface wood cell walls.

Temperature histories for various types of roof shingles, wood roof sheathing, roof rafters, and non-ventilated attics are being monitored in outdoor attic structures using simulated North American light-framed construction. This report presents 2-year data histories for annual thermal loads for western redcedar, wood–thermoplastic composite, and fiberglass shingles and for wood-based composite roof sheathing, wood rafters, and attics under these shingles.

Surface properties of wood play an important role when wood is used or processed into different commodities such as siding, joinery, textiles, paper, sorption media or wood composites. Thus, for example, the quality and durability of a wood coating are determined by the surface properties of the wood and the coating. The same is true for wood composites, as the efficiency of stress transfer from the wood component to the non-wood component is strongly influenced by the surface properties of both components. Surface properties of wood can be divided into two major groups: physical and...