Monoterpene and sesquiterpene emission estimates for the United States

Biogenic volatile organic compounds (BVOC) contribute significantly to the formation of ozone and secondary organic aerosol (SOA). The Model of Emissions of Gases and Aerosols from Nature (MEGANv2.02) is used to estimate emissions of isoprene, monoterpenes (MT), and sesquiterpenes (SQT) across the United States. Compared to the Biogenic Emission Inventory System (BEIS3.0), MEGANv2.02 estimates higher isoprene but lower MT emissions for July 2001 and January 2002. A sensitivity study of SQT and MT emission factors and algorithm parameters was conducted by assigning values to four plant functional types (PFTs) using both recent measurements and literature values. The standard deviations of the emissions factors within these PFTs were two to four times the averages because of the variation in experimental basal emissions rate data. More recently published SQT and MT basal emission rates are generally lower than those reported in the literature through 2004. With the new emissions factors, monthly average SQT emission rates for the contiguous United States are equal to 16% of the MT emissions during July and 9% of the emissions during January. The SQT emissions distribution is strongly influenced by the grass and crop PFT, for which SQT emissions data are quite limited.     

The significance of many-body interactions in physical adsorption

The significance of many-body interactions in the physical adsorption of rare gas atoms on solid surfaces has been investigated. A simple model of the system was considered in which the atoms of the solid and the adsorbed atom were represented by interacting isotropic point dipoles. The fullN-body interaction energy between the adsorbed atom and the solid was calculated exactly to lowest order in the expansion parameter [₀(₀/)²]/4d ³ (, and ₀, ₀ are the solid atom's and adsorbed atom's characteristic frequency and polarizability,d is the distance from the surface of the adsorbed atom, and is the number of atoms per unit volume in the solid). The interaction was then evaluated for the adsorption of various rare gas atoms on rare gas solids. It was found that the fullN-body interaction deviated at most by only2 1/2% from the interaction obtained by considering only two-body interactions. In addition, it was found that a finite expansion in two-, three-, ... body expressions may lead to erroneous results for the interaction energy since extensive cancellations occur between successive terms of the series.     

Arsenic in stream sediments and waters of South West England

Past mining and smelting of arsenical and associated metalliferous ores in South-west England has led to widespread contamination of soils and surface drainage. The regional distribution of arsenic in both sediments and waters of tributary drainage shows anomalies in those areas underlain by mineralised granites and their metamorphic aureoles. High concentrations of arsenic in waters correspond with high concentrations in associated sediments. Detailed studies in three river systems illustrate the large degree of variation in arsenic values between individual sampling stations but confirm the relationship between sediments and waters. The work provides evidence of the potential use of geochemical reconnaissance surveys to water quality assessment.     

Quantum states of he atoms adsorbed on surfaces of rare gas solids

Wave functions and energies for band states of helium atoms in the two-dimensional periodic potential at the surface of a semiinfinite rare gas solid have been studied. In the case of Kr and Ar substrates, the atoms are highly localized and, correspondingly, the band widths are small. In a third case, namely that of an argon crystal highly compressed to simulate the adsorption site density of the close-packed face of argon, much larger band widths were found. If this is a reasonable simulation, then band effects may be observable.     

The effects of whitening and dust accumulation on the microclimate and canopy behaviour of rose plants (Rosa hybrida) in a greenhouse in Zimbabwe

The effects of whitening and of dust accumulation on the optical properties of materials in use as greenhouse covers in Zimbabwe were investigated. The effect of whitening was investigated in a greenhouse by measuring the transmittances for total solar, photosynthetically active radiation (PAR) and thermal radiation before and after painting the cover with lime-based whitewash paint, as used for shading in Zimbabwe. In addition, to evaluate the effect of dust, the transmittances for total solar, PAR and thermal radiation of a plastic sample were measured when dirty, due to exposure to the environment for 6 months, and again after cleaning. Whitening reduced the transmission coefficients for PAR, total solar and thermal radiation of the greenhouse cover from 0.75 to 0.53; 0.74 to 0.55 and 0.45 to 0.43, respectively. Dust and dirt accumulation due to 6 months exposure to the environment reduced the transmittances for all wavebands of the plastic sample (relative to their initial values) by 16%, 15% and 13%, respectively. To investigate the effect of these changes in the optical properties on greenhouse microclimate and canopy behaviour, the measured changes in transmittances were used in the Gembloux Dynamic Greenhouse Climate Model (GDGCM). The model showed that whitening of the greenhouse roof led to significant reductions in the maximum air temperature, vapour pressure deficit, canopy-to-air temperature difference and transpiration rate, while the canopy stomatal resistance was not significantly affected. These reductions, together with a decrease in the crop water stress index, indicate that the crop was less stressed after whitening. The model showed similar, but smaller, changes to all the microclimate and canopy parameters due to the accumulation of dust on the greenhouse roof.     

Reduction of fumonisin B₁ in corn grits by twin-screw extrusion

Abstract: This study was designed to investigate the fate of fumonisins in flaking corn grits during twin‐screw extrusion by measuring fumonisin B₁ (FB₁) and its analogs with a mass balance approach. Food grade corn grits and 2 batches of grits contaminated with FB₁ at 10 and 50 μg/g by Fusarium verticillioides M‐2552 were processed with or without glucose supplementation (10%, w/w) with a twin‐screw extruder. Extrusion reduced FB₁ in contaminated grits by 64% to 72% without glucose and 89% to 94% with added glucose. In addition, extrusion alone resulted in 26% to 73% reduction in the levels of fumonisin B₂ and fumonisin B₃, while levels of both mycotoxins were reduced by >89% in extruded corn grits containing 10% glucose. Mass balance analysis showed that 38% to 46% of the FB₁ species detected in corn extruded with glucose was N‐(deoxy‐D‐fructos‐1‐yl)‐FB₁, while 23% to 37% of FB₁ species detected in extruded corn grits with and without added glucose was bound to the matrix. It was also found that the hydrolyzed form of FB₁ was a minor species in extruded corn grits with or without added glucose, representing <15% of the total FB₁ species present. Less than 46% of FB₁ originally present in corn grits could be detected in the fumonisin analogues measured in this study. Research is needed to identify the reaction products resulting from extrusion processing of fumonisin‐contaminated corn products. Practical Application: Twin‐screw extrusion is widely used in food industry for its versatility. This technology may reduce the level of fumonisins in corn particularly with added glucose.     

Renal histopathology in fatal cases of diarrhoea-associated haemolytic uraemic syndrome. British Association for Paediatric Nephrology

We report on a 32-year-old atopic female office employee with a moderate tree pollinosis who also suffered from indoor-related perennial rhinoconjunctivitis. Once when she repotted her two ornamental nonflowering green plants of the genus Tradescantia (synonym; Albifloxia; family Commelinaceae), she immediately experienced itching of the face, throat, and conjunctiva; swelling of the lips; and dyspnea and wheezing. Skin prick tests with the leaves of Tradescantia (T. albifloxia and T. fluminensis) (Ta and Tf) were strongly positive as was the specific IgE to Ta leaves extract. On RAST inhibition studies, no cross-reactivity was found between Ta and Ficus benjamina (weeping fig), a nonflowering green plant, which produces, in its milky sap, an important respiratory allergen. Green plants should be considered potential indoor allergens and tested in plant-keepers referred for allergologic investigation.     

Crystallization characteristics of methyl tallowate and its blends with ethanol and diesel fuel

Methyl tallowate was prepared from edible beef tallow via transesterification, and was blended with ethanol and/or No.2 diesel fuel in different ratios. Crystallization characteristics of methyl tallowate and its blends were studied at temperatures ranging from 22 to −16°C. Blending ethanol with methyl tallowate reduced crystal formation at all temperatures. As the temperature of the blends was reduced from 22 to 0°C, there was no effect on crystal formation of saturated vs. unsaturated fatty acids. Below 0°C, the saturated fatty acids crystallized at a much faster rate than the unsaturated fatty acids.     

Fuel properties of tallow and soybean oil esters

Fuel properties of beef tallow, soybean oil, their esters, and blends with No. 2 diesel fuel and ethanol were determined. Fuel properties tested were viscosity, specific gravity, API gravity, distillation ranges, calculated cetane index, energy content, flash point, water content, sulfur content, carbon residue, particulate matter, acid value, copper-strip corrosion test, ash content, melting point, cloud point, and pour point. Gas-chromatographic analyses of tallow, soybean oil, and their esters were performed to determine their major constituents. Viscosities of soybean oil and tallow were significantly reduced by esterification. Other fuel properties of the esters and their blends with No. 2 diesel fuel and ethanol were similar to the properties of No. 2 diesel fuel.