Treesearch

A new procedure has been developed for the rapid continuous acetylation of lignocellulosic fiber. A limited amount of acetic anhydride is applied to the fiber before the fiber goes through a reactor at high temperature. The acetylated fiber is then stripped in a first step with superheated vapor of anhydride/acetic acid and, optionally, in a second step with superheated steam to both dry the fiber and convert any un-reacted anhydride to acid making separation of byproducts easier. Fiberboards made using the acetylated fiber were much more stable to dimensional changes in both high relative...

N,N-dimethyl amino carbinol catechol borate(1). N,N-dimethyl amino carbinol-4-methyl catechol borate(2), N,N-dimethyl amino carbinol-4-t- butyl catechol borate(3). N,N-dimethyl amino carbinol-2,3-naphthyl borate 4) were synthesized by refluxing boric acid and diol in DMF(N,N-dimethyl formamide). The borates were characterized by NMR. Wood impregnated with borate 1,2 or 4 after 2-week water leaching was able to prevent decay by a brown-and white-rot fungus. TGA showed that wood impregnated with borate 1 or 4 had a high char yield. DSC showed that the pyrolysis pathway of wood treated with...

Uneven-aged and diameter-limit management were compared with an unmanaged control on the Fernow Experimental Forest near Parsons, West Virginia, to determine how treatment affects the quality of red oak (Quercus rubra L.), sugar maple (Acer saccharum Marsh.), and yellow-poplar (Liriodendron tulipifera L.). Periodic harvests slightly increased stem lean, which often causes tension wood. The grade of red oak was lower under the diameter-limit treatment compared with that of the control, but this was due primarily to tree size; in contrast, uneven-aged management improved red oak grade...

The United States is a country with a vast forest resource, comprising about one-third of its total land area (or about 3 million square kilometers). As a result, wood is an important renewable resource and is widely used in many applications! including building construction, furniture, fuelwood, textile fabrics, organic chemicals, and paper manufacture. This wide usage generates a large volume of wood waste. Currently, nearly 63 million metric tons of this material is generated in the manufacture, use, and disposal of solid wood products each year. This paper describes the types and...

Wood-inhabiting macrofungi inhabit substrata that differ in size, state of decay, and moisture content. Thus, the ecologies of fungi growing on wood differ. Wood-inhabiting species include fungi that were in or on the wood when a tree or tree part fell to the ground (e.g., pathogens and nonpathogenic endophytes of living tissue, heart rots), as well as the succession of fungi that follow in an organized fashion as the wood deteriorates. In addition, many putative and known ectomycorrhizal species “climb up” on wood to fruit and simultaneously may obtain nutrients from the wood by degrading...

In contrast to DNA, messenger RNA (mRNA) in complex substrata is rarely analyzed, in large part because labile RNA molecules are difficult to purify. Nucleic acid extractions from fungi that colonize soil are particularly difficult and plagued by humic substances that interfere with Taq polymerase (Tebbe and Vahjen 1993 and references therein). Magnetic capture techniques have overcome these problems, allowing rapid and efficient purification of microbial DNA and RNA. Magnetic capture involves the use of magnetic beads that are covalently attached to single-stranded DNA, most commonly...

Concerns about indoor air quality due to mold growth have increased dramatically in the United States. In the absence of proper moisture management, fungicides need to be developed for indoor use to control mold establishment. An ideal fungicide for prevention of indoor mold growth on wood-based materials needs to specifically prevent spore germination and provide long-term protection under conditions of high humidity. Fungicides intended for indoor use must be nontoxic, nonvolatile, odorless, and hypoallergenic. Multicomponent systems were tested in AWPA soil block tests for inhibition of...

Environmental pressures to eliminate arsenate from wood preservatives has resulted in voluntary removal of CCA for residential applications in the United States. A new generation of copper organic preservatives has been formulated to replace CCA for decking and in-ground applications but there is no guarantee that these preservatives represent a permanent solution to all related problems. Therefore, it is still necessary to evaluate alternative treatments, as well as naturally durable wood species, in order to be prepared for future changes in the field. In this study, six hardwoods and...

For decades chromated copper arsenate (CCA) was the primary preservative for treated wood used in residential construction. However, recent label changes submitted by CCA registrants will withdraw CCA from most residential applications. This action has increased interest in arsenic free preservative systems that have been standardized by the American Wood Preservers' Association. These include acid copper chromate (ACC), alkaline copper quat (ACQ), copper azole (CBA-A and CA-B), copper citrate (CC), copper dimethyldithio-carbamate (CDDC), and copper HDO (CX-A). All of these CCA alternatives...

This paper discusses results of tests conducted to expand the data base on the performance of timber rivet connections in U.S. domestic species to verify existing and proposed design procedures. Eight-, 80-, and 200-rivet connections were tested. The 8-rivet joint tests illustrate the effects of material type, rivet length, and load direction on the behavior of rivet connections when gross wood failures are avoided. The 80-rivet connections, loaded perpendicular to grain, show the effect of rivet spacing as well as test support conditions on failure mode and strength. The 200-rivet joints,...