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Quantification of the black carbon (BC) and brown carbon (BrC) components of source emissions is critical to understanding the impact combustion aerosols have on atmospheric light absorption. Multiple-wavelength absorption was measured from fuels including wood, agricultural biomass, coals, plant matter, and petroleum distillates in controlled combustion settings. Filter-based absorption measurements were corrected and compared to photoacoustic absorption results. BC absorption was segregated from the total light extinction to estimate the BrC absorption from individual sources. Results were compared to elemental carbon (EC)/organic carbon (OC) concentrations to determine composition's impact on light absorption. Multiple-wavelength absorption coefficients, Angstrom exponent (6.9 to <1.0), mass absorption cross section (MAC), and Delta C (97 μg m À3 to~0 μg m À3) were highly variable. Sources such as incense and peat emissions showed ultraviolet wavelength (370 nm) BrC absorption over 175 and 80 times (respectively) the BC absorption but only 21 and 11 times (respectively) at 520 nm wavelength. The bulk EC MAC EC, λ (average at 520 nm = 9.0 ± 3.7 m 2 g À1; with OC fraction <0.85 =~7.5 m 2 g À1) and the BrC OC mass absorption cross sections (MAC BrC,OC,λ ) were calculated; at 370 nm ultraviolet wavelengths; the MAC BrC,OC,λ ranged from 0.8 m 2 g À1 to 2.29 m 2 g À1 (lowest peat, highest kerosene), while at 520 nm wavelength MAC BrC,OC,λ ranged from 0.07 m2 g À1 to 0.37 m 2 g À1 (lowest peat, highest kerosene/incense mixture). These MAC results show that OC content can be an important contributor to light absorption when present in significant quantities (>0.9 OC/TC), source emissions have variable absorption spectra, and nonbiomass combustion sources can be significant contributors to BrC.

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Researchers at the Forest Product Laboratory (FPL) and the University of Wisconsin-Madison (UW) envision a future for biofuels based on biomass gasification with hydrogen enrichment. Synergisms between hydrogen production and biomass gasification technologies will be necessary to avoid being marginalized in the biofuel marketplace. Five feasible engineering solutions have been suggested for this synergism. We are researching one solution to investigate cleaner and more-efficient wood gasification via high-temperature liquid metal as a carrier fluid and making use of hydrogen, power, and waste heat from future nuclear reactors. The enrichment of syngas with nuclear, windmill, or solar hydrogen permits full conversion of all carbon from biomass to produce competitive synthetic gasoline, diesel, or other liquid hydrocarbon or alcohol fuels.

The combustion properties of various biomass and wood materials from various references and from our laboratory were reanalysed. The net heat of combustion for cellulosic materials was found to be 13.23 kJ/g times the ratio of stoichiometric oxygen mass to fuel mass, r o , regardless of the material composition. Bomb calorimeter data for original, charred and volatilized material components provide gross heating values, while elemental analysis of the materials for carbon, hydrogen, oxygen and ash provide direct evaluation for r o . We corrected these data as provided in various references by converting gross heating values to lower heating values and converting elemental compositions, char fractions and r o to a moisture-free and ash-free basis. Some existing formulae were found to disagree with data from vegetation, charred wood with high ash content, and with volatiles from cellulose treated with the fire retardant NaOH. We also established various functional correlations of r o with elemental compositions, or volatization fractions of untreated and treated materials, or material fractions for cellulose, lignin and extractives, or volatile fractions for tar, combustible gases and inert gases in pure nitrogen carrier gas. An interesting predictive result provides nearly constant heat of combustion while the volatile tar fraction is decreasing and combustible and inert gas fractions are increasing with time during the charring of Douglas-fir wood. Published in

Experimental quantitative damage measurements and void growth model predictions in the spallation of tantalum AIP Conf.Modelling void growth and failure of passivated metal lines under stress and electromigration conditions AIP Conf.

Mesophytic species (esp. Acer rubrum) are increasingly replacing oaks (Quercus spp.) in fire-suppressed, deciduous oak-hickory forests of the eastern US. A pivotal hypothesis is that fuel beds derived from mesophytic litter are less likely than beds derived from oak litter to carry a fire and, if they do, are more likely to burn at lower intensities. Species effects, however, are confounded by topographic gradients that affect overstory composition and fuel bed decomposition. To examine the separate and combined effects of litter species composition and topography on surface fuel beds, we conducted a common garden experiment in oak-hickory forests of the Ohio Hills. Each common garden included beds composed of mostly oak and mostly maple litter, representative of oak- and maple-dominated stands, respectively, and a mixture of the two. Beds were replenished each fall for four years. Common gardens (N = 16) were established at four topographic positions (ridges, benches on south- and northeast-facing slopes, and stream terraces) at each of four sites. Litter source and topographic position had largely independent effects on fuel beds and modeled fire dynamics after four years of development. Loading (kg m-2) of the upper litter layer (L), the layer that primarily supports flaming spread, was least in more mesic landscape positions and for maple beds, implying greater decomposition rates for those situations. Bulk density in the L layer (kg m-3) was least for oak beds which, along with higher loading, would promote fire spread and fireline intensity. Loading and bulk density of the combined fermentation and humic (FH) layers were least on stream terrace positions but were not related to species. Litter- and FH-layer moistures during a 5-day dry-down period after a rain event were affected by time and topographic effects while litter source effects were not evident. Characteristics of flaming combustion determined with a cone calorimeter pointed to greater fireline intensity for oak fuel beds and unexpected interactions between litter source and topography. A spread index, which synthesizes a suite of fuel bed, particle, and combustion characteristics to indicate spread (vs extinction) potential, was primarily affected by litter source and, secondarily, by the low spread potentials on mesic landscape positions early in the 5-day dry-down period. A similar result was obtained for modeled fireline intensity. Our results suggest that the continuing transition from oaks to mesophytic species in the Ohio Hills will reduce fire spread potentials and fire intensities.

Sustainable, non-halogenated flame retardants are desired for a variety of industry applications. Lignin, an industrially processed wood derivative, has been examined as a potential sustainable flame retardant additive to polymer systems. Here, the lignin is phosphorylated using a pyridine-catalysed esterification reaction with diphenyl phosphoryl chloride to improve its char-forming abilities. The chemical modification of the lignin was characterised by nuclear magnetic resonance spectroscopy and showed the formation of phosphorylated structures on the lignin. The thermal decomposition profile and char-forming characteristics of the modified lignin and modified lignin–epoxy composites were investigated using thermogravimetry. The flammability performance of modified lignin–epoxy composites was tested using mass loss calorimetry. With the addition of 10% modified lignin, the peak heat release rate decreased by 40% and the total heat of combustion decreased by 20%. Scanning electron microscopy was used to investigate the char morphology of the post-flame test samples and showed closed cell foam structures.