Treesearch

Polyhydroxybutyrate (PHB) was grafted onto cellulose fiber by dicumyl peroxide (DCP) radical initiation via in situ reactive extrusion. The yield of the grafted (cellulose-g-PHB) copolymer was recorded and grafting efficiency was found to be dependent on the reaction time and DCP concentration. The grafting mechanism was investigated by electron spin resonance (ESR) analysis and showed the presence of radicals produced by DCP radical initiation. The grafted copolymer structure was determined by nuclear magnetic resonance (NMR) spectroscopy. Scanning electronic microscopy (SEM) showed that...

Diffusion of chemicals and ions through the wood cell wall plays an important role in wood damage mechanisms. In the present work, free diffusion of ions through wood secondary walls and middle lamellae has been investigated as a function of moisture content (MC) and anatomical direction. Various ions (K, Cl, Zn, Cu) were injected into selected regions of 2 ìm thick wood sections with a microinjector and then the ion distribution was mapped by means of X-ray fluorescence microscopy with submicron spatial resolution. The MC of the wood was controlled in situ by means of climatic chamber...

Federal agencies are mandated to measure, manage, and reduce greenhouse gas (GHG) emissions. The General Services Administration (GSA) Carbon Footprint Tool (CFT) is an online tool built to utilize measured GHG inventories to help Forest Service units streamline reporting and make informed decisions about operational efficiency. In fiscal year 2013, the Forest Service Sustainable Operations GHG Tracking Team completed GHG inventories of three Forest Service units to compare top-down (national) and bottom-up (local) inventory reporting approaches. In this report, the Track to Zero Team...

Detectability of individual animals is highly variable and nearly always < 1; imperfect detection must be accounted for to reliably estimate population sizes and trends. hierarchical models can simultaneously estimate abundance and effective detection probability, but there are several different mechanisms that cause variation in detectability. neglecting temporary emigration can lead to biased population estimates because availability and conditional detection probability are confounded. in this study, we extend previous hierarchical binomial mixture models to account for multiple sources...

Renewable energy is expanding quickly with sometimes dramatic impacts to species and ecosystems. To understand the degree to which sensitive species may be impacted by renewable energy projects, it is informative to know how much space individuals use and how that space may overlap with planned development. We used global positioning system-global system for mobile communications (GPS-GSM) telemetry to measure year-round movements of golden eagles (Aquila chrysaetos) from the Mojave Desert of California, USA. We estimated monthly space use with adaptive local convex hulls to identify the...

Freeze-dried cellulose nanocrystals (CNCs) were dispersed in the thermoplastic polyurethane [Pellethane 2363-55D (P55D)] by a solvent casting method to fabricate CNC-reinforced nanocomposites. This study demonstrated that the addition of small amounts (1–5 wt %) of CNCs to P55D increased the thermal degradation temperature while maintaining a similar stiffness, strength, and elongation of the neat P55D. CNC additions to P55D did not alter the glass-transition temperature, but the onset decomposition temperature was shifted from 286 to 327C when 1 wt % CNCs was dispersed in the matrix. The...

This paper summarizes a cooperative project to assess the current condition and life expectancy of 132 timber highway bridge superstructures at locations throughout the United States. Several superstructure types were included in this comprehensive effort, of which two-thirds were sawn timber stringer systems. In-depth inspections were conducted by the project team using visual, probing, and nondestructive evaluation (NDE) techniques to characterize the condition of the primary bridge superstructure components. The condition of the bridges was satisfactory and better for large percentages...

Current estimates of carbon (C) storage in peatland systems worldwide indicate that tropical peatlands comprise about 15% of the global peat carbon pool. Such estimates are uncertain due to data gaps regarding organic peat soil thickness, volume and C content. We combined a set of indirect geophysical methods (ground-penetrating radar, GPR, and electrical resistivity imaging, ERI) with direct observations using core sampling and C analysis to determine how geophysical imaging may enhance traditional coring methods for estimating peat thickness and C storage in a tropical peatland system in...

Management of smoke from prescribed fires requires knowledge of fuel quantity and the amount and composition of the smoke produced by the fire to minimize adverse impacts on human health. A five-year study produced new emissions information for more than 100 trace gases and particulate matter in smoke for fuel types found in the southern United States of America using state-of-the-art instrumentation in both laboratory and field experiments. Emission factors for flaming, smoldering, and residual smoldering were developed. Agreement between laboratory and field-derived emission factors was...

Continuous forest inventory planners can allocate the budget to more plots per acre or a shorter remeasurement cycle. A higher plot intensity benefits small area estimation and allows for more precision in current status estimates. Shorter cycles may provide better estimates of growth, removals and mortality. On a fixed budget, the planner can't have both greater plot intensity and shorter cycles. Therefore, it is important to understand the trade-offs involved. Growth over removals ratios are important indicators of sustainability, and can be adversely affected by changes in cycle length....