Treesearch

At times in history, there have been concerns that demand for wood (timber) would be greater than the ability to supply it, but that concern has recently dissipated. The wood supply and demand situation has changed because of market transitions, economic downturns, and continued forest growth. This article provides a concise overview of this change as it relates to the United States, looking at nationwide trends in the pulp and paper sector and the solid wood and composite wood product sectors (lumber and wood panels) and also nationwide trends in timber growth, timber removals, and real...

This study demonstrated two in situ UV-vis spectrophotometric methods for rapid and temporally resolved measurements of cellulase adsorption onto cellulosic and lignocellulosic substrates during enzymatic hydrolysis. The cellulase protein absorption peak at 280 nm was used for quantification. The spectral interferences from light scattering by small fibers (fines) and particulates and from absorptions by lignin leached from lignocelluloses were corrected using a dual-wavelength technique. Wavelengths of 500 and 255 nm were used as secondary wavelengths for correcting spectral interferences...

Soya beans have long been considered a miracle crop for their ease of growing; high concentration of vegetable oil and high protein content; and their ability to reintroduce nitrogen back into the soil. The origin of soya beans dates back to the early 11th century from the eastern half of China. They were introduced to Europe in 1712 and first harvested in the US in 1764. With the advent of the combine harvester, soya bean growth exploded in the US from 1929 to 1939, increasing from 0.23m to 2.25m t. Today, soya beans are grown throughout the world. In 2008, an estimated 221m t of soya...

Understanding the proximate mechanisms of caste development in eusocial taxa can reveal how social species evolved from solitary ancestors. In Polistes wasps, the current paradigm holds that differential amounts of nutrition during the larval stage cause the divergence of worker and gyne (potential queen) castes. But nutrition level alone cannot explain how the first few females to be produced in a colony develop rapidly yet have small body sizes and worker phenotypes. Here, we provide evidence that a mechanical signal biases caste toward a worker phenotype. In Polistes fuscatus, the...

To better understand adhesive interactions with wood, reactions between model compounds of wood and a model compound of polymeric methylene diphenyl diisocyanate (pMDI) were characterized by solution-state NMR spectroscopy. For comparison, finely ground loblolly pine sapwood, milled-wood lignin and holocellulose from the same wood were isolated and derivatized with the pMDI model compound. One-bond 13C–1H correlation (HSQC) experiments on derivatized and dissolved ball-milled wood revealed which hydroxyl group positions of the cell wall polymers reacted with the pMDI model compound to form...

Solution-state NMR provides a powerful tool to observe the presence or absence of covalent bonds between wood and adhesives. Finely ground wood can be dissolved in an NMR compatible solvent system containing dimethylsulfoxide-d6 and N-methylimidazole-d6, in which the wood polymers remain largely intact. High-resolution solution-state two dimensional NMR correlation experiments, based on 13C–1H one-bond heteronuclear single quantum coherence, allow structural analysis of the major cell wall components. This technique was applied to loblolly pine that was treated with polymeric methylene...

This indicator shows the trend in recovering wood and paper for reuse in products in the United States. This reuse can hold down the need to harvest wood to meet U.S. consumption needs. The paper recycling rate (utilization rate in producing new paper) increased from 22% to 38% between 1970 and 1996, but then stabilized at 37% to 38% between 1996 and 2006. This rate has been stable despite continuing increase in the recovery rate of paper in the 1990s though 2006 to 51% because increases in recovery after the mid 1990s have been exported. The effects of increasing recovery after the mid...

Four equations are presented to determine bending stiffness using transverse vibration. These equations are used for constant cross-section products, panels, rectangular cross-section products, and logs with and without taper. Practical considerations for their use are discussed and concluding remarks are included.

Increased use of timber bridges in the U.S. transportation system has required additional research to improve the current design methodology of these bridges. For this reason, the U.S. Forest Service, Forest Products Laboratory (FPL), and the Federal Highway Administration have supported several research programs to attain the objective listed above. This report is a result of a study sponsored by the FPL, with the objective of determining how highway truckloads are distributed to girders of a glued-laminated timber bridge. The American Association of State Highway and Transportation...

Moisture management is critical for durable, energy-efficient buildings. To address the need for research on wind-driven rain intrusion in wall assemblies, the U.S. Forest Products Laboratory is developing a new facility. This paper describes the underlying principle of this facility and its capabilities.