Treesearch

Limitations on the use of chromated copper arsenate (CCA) have heightened interest in use of arsenic-free copper-based alternatives. For decades, the USDA Forest Products Laboratory has been evaluating several of these systems in stake plots. Southern Pine 38- by 89- by 457-mm (1.5- by 3.5- by 18-inch) stakes were treated with varying concentrations of acid copper chromate (ACC), ammoniacal copper borate (ACB), or acid copper formate (CF) and buried to one-half their length in plots within the Harrison Experimental Forest in Mississippi. Stakes treated with acidic formulations (ACC and CF)...

Analysis of genomic clones encoding a putative laccase in homokaryon strains of Ceriporiopsis subvermispora led to the identification of an allelic variant of the previously described lcs-1 gene. A cDNA clone corresponding to this gene was expressed in Aspergillus nidulans and in Aspergillus niger. Enzyme assays and Western blots showed that both hosts secreted active laccase. Relative to the isozymic forms of the native C. subvermispora enzyme, the A. niger-produced laccase had a higher molecular mass and gave a single band on IEF gels. In contrast, A. nidulans transformants secreted...

This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The molded parts produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, and Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Dynamic Mechanical Analysis (DMA), and X-ray Diffraction (XRD) analysis. Effects of processing conditions on the mechanical properties and microstructures have been studied. The results show that the supercritical fluid (N2)helps to further...

Pulp containing PSA was prepared in the laboratory and blended with sticky-free pulp in four different proportions. The four pulps were then dewatered and shipped to four laboratories for the evaluation of macro stickies in terms of mm2/kg. Also, five pulp samples from specific locations in a deinking mill were dewatered and shipped to the same four laboratories. Methods used by these laboratories include: 1. Black ink method 2. INGEDE method 3. Enzyme digestion method 4. Blue dye method Details of these methods are presented in Appendices 1 to 4. All laboratories used slotted screens to...

Gypsum board is a common fire barrier used in house and general building construction. Recently, evaluation of the collapses of the World Trade Center Towers highlighted the potential role and failure of gypsum board in containing the fires and resisting damage. The use of gypsum board as primary fire protection of light-flame wood or steel construction is ubiquitous. Yet knowledge of the common engineering mechanical properties of this construction product is nearly nonexistent. Gypsum board is used in a prescriptive manner with little or no rational design. Summarized here are the...

Compared to other substrates, wood is generally easy to bond. However, adhesion is diminished when the wood surface is covered by chemicals, whether natural oils and resins or added chemicals. Among the chemicals added to wood are fire retardants and wood preservatives. Chromated copper arsenate (CCA) has been widely used to protect wood against rot and termites, but concern about the toxicity of arsenic is leading companies to turn to other treatment chemicals (1). The two most prominent chemicals for replacing CCA in treating wood are ammonical copper quat (ACQ) and copper azole (CAz)....

This review summarizes patents related to paper recycling that were issued during the last six months of 2002. Two on-line databases, Claims/U.S. Patents Abstracts and Derwent World Patents Index, were searched for this review. This semiannual feature is intended to inform readers about recent developments in equipment design, chemicals, and process technology for recycling paper, and alternative products derived from postconsumer paper. Only brief summaries of individual inventions are included in this review. Because many of the patents are not readily available in English, much of the...

Collapse of fiberboard packaging boxes, in the shipping industry, due to rise in humidity conditions is common and very costly. A 3D FE nonlinear model is developed to predict the moisture flow throughout a corrugated packaging fiberboard sandwich structure. The model predicts how the moisture diffusion will permeate through the layers of a fiberboard (medium and facings). The model predicts the deformation response, the loss of stiffness, and the creep response. The FE results are compared with an experimental set-up used at the Forest Product Laboratory in Madison, WI for a panel...

D-Glucose metabolism is thought to be important during wood decay by fungi, not only for anabolic and catabolic purposes of central metabolism, but also as a potential source of peroxide required by extracellular peroxidases. There has been some confusion in the literature as to whether this peroxide-generating activity is of the glucose 1-oxidase or pyranose 2-oxidase (glucose 2-oxidase) type with various fungi or even within the same fungal species. Definitive classification requires accurate identification of the enzymatic products D-glucono- 1,5-lactone and D- arabino-2-hexosulose...

Radiocarbon dating and 40 Ar/39Ar analysis of overlying tephra indicate that plant fossil assemblages exposed by stream erosion and well construction in and near La Selva Biological Station in eastern lowland Costa Rica are Pleistocene in age. We identified plant taxa based on wood, leaves, fruits, seeds, pollen, and spores examined from three sites at ca 30 m elevation. Extrapolating from modern ranges and surface temperature lapse rates suggests paleotemperatures 2.5-3.1°C cooler than at present.