Treesearch

There is a need to develop models that evaluate the interaction of wood adhesives at the macroscopic level to explain observations on the durability of bonded wood laminate products with changing moisture conditions. This paper emphasizes a model that relates durability to strain on the bondline caused by wood swelling. The effect of this strain is discussed in relation to two groups of adhesives with different chemistry, structure-property and adhesive-wood interaction relationship models. The in situ polymerized adhesive group involves highly cross-linked polymers with a rigid backbone...

Fire-resistive wood construction is achieved either by having the structural elements be part of fire-rated assemblies or by using elements of sufficient size that the elements themselves have the required fire-resistance ratings. For exposed structural wood elements, the ratings in the United States are calculated using either the T.T. Lie method or the National Design Specifications (NDS) Method. There is no widely accepted methodology in the United States to determine the fire-resistance rating of an individual structural wood element with the protective membrane directly applied to the...

This study established a novel process using sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust and efficient bioconversion of softwoods. The process consists of sulfite treatment of wood chips under acidic conditions followed by mechanical size reduction using disk refining. The results indicated that after the SPORL pretreatment of spruce chips with 8-10% bisulfite and 1.8-3.7% sulfuric acid on oven dry (od) wood at 180 °C for 30 min, more than 90% cellulose conversion of substrate was achieved with enzyme loading of about 14.6 FPU cellulose plus 22.5 CBU...

Currently, many of the polymer-coated fasteners on the market are designed for improved corrosion performance in treated wood; yet, there is no way to evaluate their corrosion performance. In this study, a common technique for measuring the corrosion performance of polymer-coated metals, electrochemical impedance spectroscopy (EIS), was used to evaluate commercial fasteners in a water extract of treated wood. Fasteners were tested in an "out of the box" condition as well as after being driven into the wood to simulate service conditions. The EIS spectra were fit to the traditional model...

Many timber trestle railroad bridges in Wisconsin have experienced deterioration and are in need of rehabilitation. In addition, the railroad industry is increasing the weights of cars. The combined effect of heavier loads and deterioration threatens to cut short the service life of timber bridges. One of the most critical problems that has been identified was the overloading of timber piles in bridges, which can be remedied by creating a stiffer pile cap. The goal of this investigation was to show that mechanically fastened fiber reinforced polymer (MF¬FRP) strips fastened to timber with...

It is unlikely that a single antimicrobial compound, whether synthetic or natural, will provide the ‘magic bullet’ for eliminating multiple biological agents affecting wood products. Development of synergistic combinations of selected compounds, especially those derived from natural sources, is recognized as a promising approach to improved wood protection. Recent adoption of effective fungicide technology in food sanitation and agriculture to applications in wood protection has led to the development of novel wood protectants. Specifically, formulations that incorporate low molecular...

Uncertainties in the contribution that biofuels might make in meeting the energy needs of the transportation sector in the western US by 2015 were addressed by combining a spatially-explicit resource inventory and assessment, models of conversion technologies, and transportation costs into an integrated model of biofuel supply chains. Geographic Information System (GIS) modeling was used in conjunction with an infrastructure system cost optimization model to develop biofuel supply curves using biomass feedstocks throughout the western US. Biofuels could provide between 5 and 10 percent of...

The extracellular heme-thiolate peroxygenase of Agrocybe aegerita catalyzed the H2O2-dependent hydroxylation of 2-phenoxypropionic acid (POPA) to give the herbicide precursor 2-(4-hydroxyphenoxy)propionic acid (HPOPA). The reaction proceeded regioselectively with an isomeric purity near 98%, and yielded the desired R-isomer of HPOPA with an enantiomeric excess of 60%. 18O-labeling experiments showed that the phenolic hydroxyl in HPOPA originated from H2O2, which establishes that the reaction is mechanistically a peroxygenation. Our results raise the possibility that fungal peroxygenases...

Overexpression of D-xylulokinase in Saccharomyces cerevisiae engineered for assimilation of xylose results in growth inhibition that is more pronounced at higher xylose concentrations. Mutants deficient in the para-nitrophenyl phosphatase, PHO13, resist growth inhibition on xylose. We studied this inhibition under aerobic growth conditions in well-controlled bioreactors using engineered S. cerevisiae CEN.PK. Growth on glucose was not significantly affected in pho13Δ mutants, but acetate production increased by 75%. Cell growth, ethanol production, and xylose consumption all increased...

The correlations between the intrinsic viscosity of fiber suspensions and 17 measures of fiber shape were investigated. The intrinsic viscosities of suspensions of fibers with various shapes and aspect ratios were determined numerically. The shapes studied include different degrees of fiber curvature, angular bends, helical shapes, randomly generated shapes, and others. The shape measure that correlated most strongly with intrinsic viscosity was an invariant of the hydrodynamic resistance tensor; this invariant is related to the hydrodynamic drag coefficients on a fiber translating in the...