Treesearch

The structure of wood cell wall cellulose in its native state remains poorly understood, limiting the progress of research and development in numerous areas, including plant science, biofuels, and nanocellulose based materials. It is generally believed that cellulose in cell wall microfibrils has both crystalline and amorphous regions. However, there is evidence that appears to be contrary to this assumption. Here we show, using 1064-nm FT-Raman spectroscopy, that (1) compared to the crystalline state, cellulose in the never-dried native state is laterally aggregated but in a less-than...

As wood reaches elevated temperatures, the different chemical components undergo thermal degradation that affect the performance of wood. The extent of these changes depends on the temperature level and length of time under exposure conditions. Permanent reductions in strength and modulus of elasticity can occur at temperatures >65 °C, with the amount depending on the temperature, pH of wood, moisture content, heating medium, exposure period, chemical treatment, and species (Winandy and Rowell, 2013). Studies relating strength reduction with temperature rise has indicated a kinetic...

Magnetic resonance imaging (MRI) was used to evaluate free water content and distribution in wood-plastic composite (WPC) materials decayed during exterior exposure near Hilo, Hawaii. Two segments of the same board blend were selected from 6 commercial decking boards that had fungal fruiting bodies. One of the two board segments was exposed in sun, the other in shadow. Whole board segments were imaged using a clinical MRI unit, and cross-section segments were inspected using scanning electron microscopy (SEM). Samples were cut from the cross section of the board to determine material...

Since uncertainty remains about how white rot fungi oxidize and degrade lignin in wood, it would be useful to monitor changes in fungal gene expression during the onset of ligninolysis on a natural substrate. We grew Phanerochaete chrysosporium on solid spruce wood and included oxidant-sensing beads bearing the fluorometric dye BODIPY 581/591 in the cultures. Confocal fluorescence microscopy of the beads showed that extracellular oxidation commenced 2 to 3 days after inoculation, coincident with cessation of fungal growth. Whole transcriptome shotgun sequencing (RNA-seq) analyses based on...

The mountain pine beetle-killed lodgepole pine (Pinus contorta) wood treated with iron (III) nitrate solution was used for the preparation of Fe-cored carbon nanomaterials (Fe-CNs) under various carbonization temperatures. The carbonization yield of Fe-treated sample (5% as Fe) was always 1–3% higher (after ash compensation) than that of the non-treated samples heated at the same condition.The lowest carbonization temperature required to produce Fe-CNs was 700° C. The carbon shell was composed of 30–40 well-aligned layers of graphitic carbon nanostructure.The iron captured by graphitic...

Previous research revealed that stress wave nondestructive testing techniques could be used to evaluate the tensile and flexural properties of wood-based composite materials. Regression models were developed that related stress wave transmission characteristics (velocity and attenuation) to modulus of elasticity and strength. The developed regression models accounted for over 94% of these materials’ observed elastic properties and for over 90% of their observed strength. The original models were developed using wood-based particle composite specimens. The study presented in this paper...

The use of a variety of stress wave transmission techniques for the in-service condition assessment of deteriorated wood is well documented. This paper summarizes results from an extensive study designed to examine the relationship between ultrasound transmission times and the deterioration of exposed wood. Two hundred seventy (270) southern pine lumber specimens were evaluated nondestructively using a through transmission ultrasound technique after field exposure for periods of up to fifty seven (57) months. Ultrasound transmission times increased with exposure time. Several statistical...

The 19th International Nondestructive Testing and Evaluation of Wood Symposium was hosted by the University of Campinas, College of Agricultural Engineering (FEAGRI/UNICAMP), and the Brazilian Association of Nondestructive Testing and Evaluation (ABENDI) in Rio de Janeiro, Brazil, on September 22–25, 2015. This Symposium was a forum for those involved in nondestructive testing and evaluation (NDT/NDE) of wood and brought together many NDT/NDE users, suppliers, international researchers, representatives from various government agencies, and other groups to share research results, products,...

In this paper, we attempted to simulate stress wave propagation in virtual tree trunks and construct two dimensional (2D) wave-front maps in the longitudinal-radial section of the trunk. A tree trunk was modeled as an orthotropic cylinder in which wood properties along the fiber and in each of the two perpendicular directions were different. We used the COMSOL Multiphysics® software to conduct numerical simulations. Field stress wave timing measurements were then conducted on three freshly cut larch (Larix principis-rupprechtii Mayr) logs to validate the simulation results. The 2D wave...

This study evaluated the influence of a variety of construction techniques on the performance of plywood siding and the applied paint, using both ultrasound and conventional visual inspection techniques. The impact of bottom edge contact, flashing vs. caulking board ends, priming the bottom edge, location (Wisconsin vs. Mississippi) and a gap behind the siding to facilitate drainage were tested. Test fences were constructed to provide outdoor exposure of 2 replicates of each permutation using full factorial design. Yellow poplar (Liriodendron tulipifera), a decay prone wood species was...