Treesearch

With global urbanization trends, the demands for tall residential and mixed-use buildings in the range of 8~20 stories are increasing. One new structural system in this height range are tall wood buildings which have been built in select locations around the world using a relatively new heavy timber structural material known as cross laminated timber (CLT). With its relatively light weight, there is consensus amongst the global wood seismic research and practitioner community that tall wood buildings have a substantial potential to become a key solution to building future seismically...

The research reported here focuses on the use of time and frequency domain analysis techniques for assessing the internal condition of timbers. Several large timbers obtained from a historic public viewing tower were evaluated with acoustic-based nondestructive testing techniques. Waveforms were captured and analyzed using both time and frequency domain techniques. The slope of the phase with respect to frequency shows potential to be a metric that is more sensitive to the presence of internal decay than time of flight.

Currently, various chemical-mechanical treatments were widely used in biofuel production to achieve high total sugar yields. However, the interaction between two treatments was scarcely investigated. In this study, we employed a ball milling process to create ultrastructural changes for Douglas-fir (Pseudotsuga menziesii) micronized wood powders. The 0, 30, and 60 min ball milled wood powders resulted in a crystallinity index of 0.41, 0.21, and 0.10 respectively. It was found that the ultrastructural changes accelerate monomeric sugars production without influencing the yield of sugar...

Mechanical milling demonstrates potential in the pretreatment arena to valorize lignocellulosic biomass because it eliminates chemicals and simplifies processing. The development of physical properties and energy consumption for generating micronized particles are key factors affecting potential use. This study investigated the effect of input moisture content, and feedstock particle size on developing physical characteristics of micronized particles and the resultant specific energy consumption in the milling process. Wood particles with different sizes were effectively comminuted to...

The hierarchical structure of wood cell walls resulting from complex arrangement and distribution of the heterogeneous components is considered to impact significant impediment to enzymatic hydrolysis of cellulose for biofuels. In this work, micronized wood with significant cell wall ultrastructural deconstruction were effectively produced from ring and puck milling within 12 min. In a subsequent enzymatic hydrolysis, micronized wood resulted in increase of cellulose hydrolysability by 4–14 folds over that of starting material. The underlying mechanism towards facilitating enzymatic...

This study was aimed to identify the best approach of incorporating cellulose nanocrystals (CNCs) into a poly (lactic acid) (PLA) matrix by examining two different CNC addition approaches. The first approach consisted of melt-blending (MB) PLA and CNCs in a three-piece internal mixer whereas the second method involved direct drymixing of PLA and CNCs in a high intensity mixer. The compounded materials were then blown into films and compared in terms of particle dispersion, optical, thermal, molecular weight and barrier properties. Good distribution was achieved by both the direct dry- and...

Delays incurred by loggers hauling wood from the landing to the mill affect profitability and have the potential to make harvesting some areas unfeasible. Minimal research has been conducted to analyze driver’s delays for round trip turn times. In order to accurately gather information concerning delay times at the mill, the landing, and during travel to and from each location, a phone app was created that recorded driver location using GPS. This app also allowed the driver to input the reason for their delays, record their fuel stops, delivery scale tickets, load sheet numbers, starting...

Endoxylanases are important enzymes in bioenergy research because they specifically hydrolyze xylan, the predominant polysaccharide in the hemicellulose fraction of lignocellulosic biomass. For effective biomass utilization, it is important to understand the mechanism of substrate recognition by these enzymes. Recent studies have shown that the substrate specificities of bacterial and fungal endoxylanases classified into glycoside hydrolase family 30 (GH30) were quite different. While the functional differences have been described, the mechanism of substrate recognition is still unknown....

Peatlands are widespread throughout the tropical Andean páramo. Despite the large carbon stocks in these ecosystems, carbon dioxide (CO2) and methane (CH4) flux data are lacking. In addition, cattle grazing is widespread in the páramo and could alter gas fluxes. Therefore, our objectives were to measure CO2 and CH4 fluxes with the static chamber technique in an undisturbed and in an intensively cattle grazed peatland in the mountains of Ecuador. We found that hummocks in the undisturbed site had higher net ecosystem exchange (NEE), gross primary production (GPP), ecosystem respiration...

Although wood makes up the majority of forest biomass, the importance of wood contributions to stable soil carbon (C) pools is uncertain. Complex interactions among climate, soil physical properties, intrinsic properties of woody residues, and biological processes all exert dynamic controls over the stabilization, destabilization and transport of wood-derived C in soils. Many studies have demonstrated the strong physical controls on decomposition rates in soils, but little work has been done to relate these to changes in decomposer community composition and how this influences the fate of...