Treesearch

Wood specific gravity (SG) has long been used by foresters as an index for wood properties. More recently, SG has been widely used by ecologists as a plant functional trait and as a key variable in estimates of biomass. However, sampling wood to determine SG can be problematic; at present, the most common method is sampling with an increment borer to extract a bark-to-pith core-a difflcult task requiring considerable physical eflort and sometimes repeated borings to hit the pith, with potential to damagc the trunk of small trees. Here, we test a novel sampling method that reduces the...

The diversity of tropical trees has captivated botanists for centuries. Woods of difterent species, not only differ in appearance, but also in functional traits-density, porosity and strength-characteristics that relate to various plant functions such as support and conduction. The specific gravity (SG) of wood is a species' trait that integrates mechanical strength properties and sometimes efliciency of conduction and resistance to embolism (Chave et al., 2009; Zanne et al., 2010). In addition, where light is limiting, growth rates and mortality rates are often inversely related to...

The effect of the embedding medium on the nano-indentation measurements of lignocellulosic materials was investigated experimentally using nano-indentation. Both the reduced elastic modulus and the hardness of nonembedded cell walls were found to be lower than those of the embedded samples, proving that the embedding medium used for specimen preparation on cellulosic material during nano-indentation can modify cell-wall properties. This leads to structural and chemical changes in the cell-wall constituents, changes that may significantly alter the material properties. Further investigation...

In this paper we are reporting on the first successful campaign of systematic, automated and massive multiaxial tests for composite material constitutive characterization. The 6 degrees of freedom system developed at the Naval Research Laboratory (NRL) called NRL66.3, was used for this task. This was the inaugural run that served as the validation of the proposed overall constitutive characterization methodology. It involved accomplishing performing I152 tests in 12 business days reaching a peak throughput of 212 tests per day. We describe the context of the effort in terms of the reasoning...

Additives were tested for their ability to modify the rheology of lignocellulosic biomass. Additive types included water-soluble polymers (WSPs), surfactants, and fine particles. WSPs were the most effective rheological modifiers, reducing yield stresses of concentrated biomass by 60–80% for additive concentrations of 1–2 wt. % (based on mass of dry biomass solids). Yield stress and plastic viscosity of rheologically modified biomass depended on WSP molecular weight and degree of substitution. The apparent shear stress-shear rate data are represented with the Bingham model. In the absence...

Static life cycle assessment does not fully describe the carbon footprint of construction wood because of carbon changes in the forest and product pools over time. This study developed a dynamic greenhouse gas (GHG) inventory approach using US Forest Service and life-cycle data to estimate GHG emissions on construction wood for two different end-of-life scenarios. Biogenic and fossil GHG emissions sources included a growing forest, logging slash, softwood lumber manufacturing, residue decay and combustion, and product in the landfill. The two scenarios focused on 1) disposing of old wood...

Over the span of three months in 2008, 2232 baseball bats broke while being used during Major League Baseball (MLB) games; of which 756 were classified as Multi Piece Failures (MPFs). This rate of failure motivated Major League Baseball to explore options for potential changes in the bat regulations to reduce the rate. After a study of the information that could be extracted from the 756 MPF bats, MLB implemented new bat regulations and inspection processes for both the wood billets and the final bats. Part of the study concluded that the maple bats used in 2008 were three times more...

Juvenile wood (core wood) is typically characterized as being less dimensionally stable and having lower mechanical properties than mature wood. Determination of the age of transition from juvenile wood to mature wood can provide basic information needed to assess dimensional stability and better utilize small-diameter trees growing in the intermountain west as solid-sawn products and as structural composites. While there is considerable information available on the variation of specific gravity with the age of the tree for westem conifers, specific gravity is not useful for predicting...

Unbleached (gray) cotton needle-punched nonwoven (NW) fabrics with 12.5% polypropylene scrim were treated with two phosphate–nitrogen-based flame retardant (FR) formulations, Southern Regional Research Center (SRRC)-1 and SRRC-2. The SRRC-1 formulation contains diammonium phosphate as the FR chemical along with urea and dimethyloldihydroxyethyleneurea. Because a trace amount of formaldehyde was still expected to be released from SRRC-1-treated FR cotton under high heat, it was preferable to eliminate the dimethyloldihydroxyethyleneurea, leading to the revised formulation SRRC-2. It has a...

Background: The first genome of a selective lignin degrader is available. Results: Its screening shows 26 peroxidase genes, and 5 genes were heterologously expressed and the catalytic properties investigated. Conclusion: Two new peroxidases oxidize simple and dimeric lignin models and efficiently depolymerize lignin. Significance: Although lignin peroxidase and versatile peroxidase had not been reported in C. subvermispora, the genomic screening suggests the presence of related lignin-degrading enzymes.