Treesearch

Because of the large percentage of juvenile wood in small-diameter southern pine, this material has lower strength properties compared with the historic published values in the ASTM Standard D2555. Finding new, simple, and inexpensive ways of increasing these strength properties would increase the use of this material for residential construction. For this study, we chose in situ polymerization using the monomer 1,6-hexanediol dimethacrylate to enhance bending strength and stiffness. After determining the lower range of density, modulus of rupture (MOR), and modulus of elasticity (MOE) of...

This report provides an assessment of technology used in manufacturing modular homes in the United States, and that used in the German prefabricated wooden home industry. It is the first step toward identifying the research needs in automation and manufacturing methods that will facilitate mass customization in the home manufacturing industry. Within the United States, a relatively low level of technology was found in domestic modular home manufacturers. Raw material transportation was mostly manual; manually operated saws sized raw materials; cranes were used to move subassemblies, and...

Few building materials possess the environmental benefits of wood. It is not only the most widely used building material in the United States but also one with characteristics that make it suitable for a wide range of applications. Efficient, durable, and useful wood products produced from trees range from a minimally processed log at a log-home building site to a highly processed and highly engineered wood composite manufactured in a large production facility. As with any resource, it is imperative that the raw materials are produced and used to ensure sustainability. One of the greatest...

Mold growth was observed in limited areas in a two-story contemporary wood-frame house during the seventh heating season of operation at or near design indoor humidity levels. The house was in a cold climate (Madison, Wisconsin). Humidity levels were estimated as being exceeded in one of 10 homes at this location. Moderate amounts of window condensation were observed during each of the seven heat­ing seasons. Areas of observed mold growth were limited to the lower extremities of windows (near the lower edge of glass panes) and the edges of lower panels of a wood panel entry door that was...

Between 2006 and the end of 2009, the production capacity of the softwood lumber sector covered by this report in the United States and Canada has shrunk from 190.8 million m3 (nominal) to 166.4 million m3. The corresponding number of mills slumped from 1,025 to 875 over the same time and from 1,322 recorded in 1995. The Canadian capacity went from 88.2 million m3 to 71.6 million m3, a loss of 19%, while the U.S. capacity dropped from 102.6 million m3 to 94.8 million m3, a loss of 8%. These losses are attributable to three unprofitable years of sawmilling caused by the contraction in...

This study examines the effect of cyclic RH exposure on MC and thickness swelling (TS) of oriented strandboard (OSB) made from fire-impacted trees. Two specimens were cut from the center of each OSB panel and one was edge-sealed. After being conditioned to 65% RH, specimens were placed in a climate-controlled chamber and subjected to three cyclic changes of 90 – 30% RH at 20°C. Experimental data were characterized by three time-dependent MC or TS models: logarithmic, power law, and exponential. The latter two models gave the best fits showing that edge-sealing reduced the extent of...

Compacted powders of commercially available nano- and microparticles of silver were used to successfully induce the surface enhanced Raman scattering (SERS) effect in spruce milled-wood lignin (MWL). For the two silver particle sizes used in this investigation, the spectra were mostly similar. Some general characteristics of the lignin SERS spectrum are described. The SERS technique was found to be sensitive for detecting lignin. Significant spectral changes were present between the SERS and normal Raman spectra of MWL. The SERS spectrum was assigned on the basis of literature-reported...

This study demonstrates sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust bioconversion of hardwoods. With only about 4% sodium bisulfite charge on aspen and 30-min pretreatment at temperature 180[degrees]C, SPORL can achieve near-complete cellulose conversion to glucose in a wide range of pretreatment liquor of pH 2.0–4.5 in only about 10 h enzymatic hydrolysis. The enzyme loading was about 20 FPU cellulase plus 30 CBU Beta-glucosidase per gram of cellulose. The production of fermentation inhibitor furfural was less than 20 mg/g of aspen wood at pH 4.5....

The presented work reports the isolation and heterologous expression of the p2ox gene encoding the flavoprotein pyranose 2-oxidase (P2Ox) from the basidiomycete Phanerochaete chrysosporium. The p2ox cDNA was inserted into the bacterial expression vector pET21a(+) and successfully expressed in Escherichia coli. We obtained active, fully flavinylated recombinant P2Ox in yields of approximately 270 mg/lmedium. The recombinant enzyme was provided with an N-terminal T7-tag and a C-terminal His6-tag to facilitate simple one-step purification. We obtained an apparently homogenous enzyme preparatio...

Efficient fermentation of hemicellulosic sugars is critical for the bioconversion of lignocellulosics to ethanol. Efficient sugar uptake through the heterologous expression of yeast and fungal xylose/glucose transporters can improve fermentation if other metabolic steps are not rate limiting. Rectification of cofactor imbalances through heterologous expression of fungal xylose isomerase or modification of cofactor requirements in the yeast oxidoreductase pathway can reduce xylitol production while increasing ethanol yields, but these changes often occur at the expense of xylose utilization...