Corporate financial reporting : the benefits and problems of disclosure : a symposium, Seaview Country Club, Absecon, New Jersey, November 20-22, 1974

https://egrove.olemiss.edu/aicpa_assoc/1508/thumbnail.jp

Spatially resolved spectral determination of polysaccharides in hydrothermally carbonized biomass

Reliable information on the decomposition of polysaccharides is important to evaluate the evolution and properties of hydrothermally carbonized chars. Hyperspectral imaging offers a quick and robust alternative to expensive and time-consuming laboratory methods to determine the polysaccharide contents of biomass and biomass-derived chars. Here, we show that the decomposition of hemicellulose and cellulose were visible in the acquired hyperspectral images even without image calibration. Image regression based on sample holocellulose, glucan and the sum of xylan, galactan, arabinan and mannan provided good calibration models and enabled visualizing the decomposition of polysaccharides based on carbonization temperature. Hyperspectral imaging thus provides a non-destructive alternative to traditional polysaccharide analyses of hydrochars for laboratory and potential future industrial applications.Peer reviewe

Reactivity of cellulose during hydrothermal carbonization of lignocellulosic biomass.

Hydrothermal carbonization (HTC) of pure cellulose (CE) and birchwood (BW) samples was carried out at temperatures between 160 and 280 °C, 0.5 h residence time and biomass-to-water ratio 1:5, to investigate the reactivity of cellulose in lignocellulosic biomass. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) showed that the CE samples remained unaltered at temperatures up to 220 °C, but were significantly decomposed at 230 °C producing a thermal recalcitrant aromatic and high energy-dense material. FTIR showed that dehydration and aromatization reactions occurred at temperature equal or higher than 230 °C for the CE samples while a similar increase in aromatization for the BW hydrochars was evident only at temperatures equal or higher than 260 °C. Acid hydrolysis, TGA and FTIR suggested that a higher thermal resistance of naturally occurring cellulose in BW (when compared to CE sample) could be related to a ‘protecting shield’ offered by interlinked lignin in the plant matrix

The contributions of snow, fog, and dry deposition to the summer flux of anions and cations at Summit, Greenland

Experiments were performed during the period May–July of 1993 at Summit, Greenland. Aerosol mass size distributions as well as daily average concentrations of several anionic and cationic species were measured. Dry deposition velocities for SO42− were estimated using surrogate surfaces (symmetric airfoils) as well as impactor data. Real-time concentrations of particles greater than 0.5 μm and greater than 0.01 μm were measured. Snow and fog samples from nearly all of the events occurring during the field season were collected. Filter sampler results indicate that SO42− is the dominant aerosol anion species, with Na+, NH4+, and Ca2+being the dominant cations. Impactor results indicate that MSA and SO42− have similar mass size distributions. Furthermore, MSA and SO42− have mass in both the accumulation and coarse modes. A limited number of samples for NH4+ indicate that it exists in the accumulation mode. Na, K, Mg, and Ca exist primarily in the coarse mode. Dry deposition velocities estimated from impactor samples and a theory for dry deposition to snow range from 0.017 cm/s +/− 0.011 cm/s for NH4+ to 0.110 cm/s +/− 0.021 cm/s for Ca. SO42− dry deposition velocity estimates using airfoils are in the range 0.023 cm/s to 0.062 cm/s, as much as 60% greater than values calculated using the airborne size distribution data. The rough agreement between the airfoil and impactor-estimated dry deposition velocities suggests that the airfoils may be used to approximate the dry deposition to the snow surface. Laser particle counter (LPC) results show that particles \u3e 0.5 μm in diameter efficiently serve as nuclei to form fog droplets. Condensation nuclei (CN) measurements indicate that particles \u3c 0.5 μm are not as greatly affected by fog. Furthermore, impactor measurements suggest that from 50% to 80% of the aerosol SO42−serves as nuclei for fog droplets. Snow deposition is the dominant mechanism transporting chemicals to the ice sheet. For NO3−, a species that apparently exists primarily in the gas phase as HNO3(g), 93% of the seasonal inventory (mass of a deposited chemical species per unit area during the season) is due to snow deposition, which suggests efficient scavenging of HNO3(g) by snowflakes. The contribution of snow deposition to the seasonal inventories of aerosols ranges from 45% for MSA to 76% for NH4+. The contribution of fog to the seasonal inventories ranges from 13% for Na+ and Ca2+ to 26% and 32% for SO42− and MSA. The dry deposition contribution to the seasonal inventories of the aerosol species is as low as 5% for NH4+ and as high as 23% for MSA. The seasonal inventory estimations do not take into consideration the spatial variability caused by blowing and drifting snow. Overall, results indicate that snow deposition of chemical species is the dominant flux mechanism during the summer at Summit and that all three deposition processes should be considered when estimating atmospheric concentrations based on ice core chemical signals

A next-generation inverse-geometry spallation-driven ultracold neutron source

The physics model of a next-generation spallation-driven high-current ultracold neutron (UCN) source capable of delivering an extracted UCN rate of around an-order-of-magnitude higher than the strongest proposed sources, and around three-orders-of-magnitude higher than existing sources, is presented. This UCN-current-optimized source would dramatically improve cutting-edge UCN measurements that are currently statistically limited. A novel "Inverse Geometry" design is used with 40 L of superfluid $^4$He (He-II), which acts as a converter of cold neutrons (CNs) to UCNs, cooled with state-of-the-art sub-cooled cryogenic technology to $\sim$1.6 K. Our design is optimized for a 100 W maximum heat load constraint on the He-II and its vessel. In our geometry, the spallation target is wrapped symmetrically around the UCN converter to permit raster scanning the proton beam over a relatively large volume of tungsten spallation target to reduce the demand on the cooling requirements, which makes it reasonable to assume that water edge-cooling only is sufficient. Our design is refined in several steps to reach $P_{UCN}=2.1\times10^9\,/$s under our other restriction of 1 MW maximum available proton beam power. We then study effects of the He-II scattering kernel as well as reductions in $P_{UCN}$ due to pressurization to reach $P_{UCN}=1.8\times10^9\,/$s. Finally, we provide a design for the UCN extraction system that takes into account the required He-II heat transport properties and implementation of a He-II containment foil that allows UCN transmission. We estimate a total useful UCN current from our source of $R_{use}=5\times10^8\,/$s from a 18 cm diameter guide 5 m from the source. Under a conservative "no return" approximation, this rate can produce an extracted density of $>1\times10^4\,/$cm$^3$ in $<$1000~L external experimental volumes with a $^{58}$Ni (335 neV) cut-off potential.Comment: Submitted to Journal of Applied Physic

Regge calculus from a new angle

In Regge calculus space time is usually approximated by a triangulation with flat simplices. We present a formulation using simplices with constant sectional curvature adjusted to the presence of a cosmological constant. As we will show such a formulation allows to replace the length variables by 3d or 4d dihedral angles as basic variables. Moreover we will introduce a first order formulation, which in contrast to using flat simplices, does not require any constraints. These considerations could be useful for the construction of quantum gravity models with a cosmological constant.Comment: 8 page

A high-field adiabatic fast passage ultracold neutron spin flipper for the UCNA experiment

The UCNA collaboration is making a precision measurement of the β asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be ϵ(overbar) = 0.9985(4)