Treesearch

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...

Pyranose 2-oxidase (POX) was recovered from Phanerochaete chrysosporium BKM-F-1767 solid substrate culture using mild extraction conditions and was purified. 13C-nuclear magnetic resonance confirmed production of D- arabino -hexos-2-ulose (glucosone) from D-glucose with the oxidase. Peptide fingerprints generated by liquid chromatography-tandem mass spectrometry of tryptic digests and analysis of the corresponding cDNA revealed a structurally unusual sequence for the P. chrysosporium POX. Relatively high levels of pox transcript were detected under carbon- starved culture conditions but...

We are developing chemically bonded ceramic phosphate binders for the production of biofiber-based composite materials. These binders promise to have better processing and properties than some current cement and polymer resin binder systems. The ceramic phosphate binders (termed Ceramicrete), if used in place of cement and polymers, will significantly reduce the overall consumption of energy, curtail detrimental environmental effects compared to existing processes, and produce wood-based composite products with enhanced fire resistance, mildew resistance, dimensional stability, and...

Spruce thermomechanical pulp was bleached initially by alkaline hydrogen peroxide and then by sodium dithionite and sodium borohydride. Near-infrared Fourier-transform–Raman spectroscopy revealed that spectral differences were due primarily to coniferaldehyde and p-quinone structures in lignin, new direct evidence that bleaching removes p-quinone structures. In unbleached pulp, the contribution of p-quinones was detected in the 1665–1690 cm–1 region. This contribution was removed to varying degrees in bleached pulps, depending on the extent to which the pulps were brightened. The relative...

Builders were surveyed to explore perceptions regarding small-diameter roundwood (SDR). The study empirically tests a model of builders’ attitudes and opinions about using SDR as a building material in recreational buildings. Findings suggest that, of the 130 builders surveyed, most are likely to use SDR in recreational buildings when it meets the following criteria: 1) a pleasing aesthetic that blends in with the environment; 2) easy and convenient to work with; 3) readily available and long lasting; and 4) when they are empowered to make SDR purchase decisions. Additionally, builders are...

Quinone reductases (QRDs) have two important functions in the basidiomycete Gloeophyllum trabeum, which causes brown rot of wood. First, a QRD is required to generate biodegradative hydroxyl radicals via redox cycling between two G. trabeum extracellular metabolites, 2,5-dimethoxyhydroquinone (2,5-DMHQ) and 2,5-dimethoxy-1,4-benzoquinone (2,5- DMBQ). Second, because 2,5-DMBQ is cytotoxic and 2,5-DMHQ is not, a QRD is needed to maintain the intracellular pool of these metabolites in the reduced form. Given their importance in G. trabeum metabolism, QRDs could prove useful targets for new...

A cluster of multicopper oxidase genes (mco1, mco2, mco3, mco4) from the lignin-degrading basidiomycete Phanerochaete chrysosporium is described. The four genes share the same transcriptional orientation within a 25 kb region. mco1, mco2 and mco3 are tightly grouped, with intergenic regions of 2.3 and 0.8 kb, respectively, whereas mco4 is located 11 kb upstream of mco1. All are transcriptionally active, as shown by RT-PCR. Comparison of cDNAs and the corresponding genomic sequences identified 14–19 introns within each gene. Based on homology and intron composition, two subfamilies of mco...

Public and private forests are in critical need of restoration by thinning small-diameter timber. If economical and value-added uses for this thinned material can be found, forest restoration costs could be offset and catastrophic wildfires would be minimized. At the same time, forestry- dependent rural communities?faced with diminishing timber supplies, loss of jobs, high unemployment, and declining community vitality?are looking for new ways to make a living from nearby forests. From information gathered in onsite interviews, this report describes how several businesses and community...