Effect of fuels and domestic heating appliance types on emission factors of selected organic pollutants

This study reports on the first complex data set of emission factors (EFs) of selected pollutants from combustion of five fuel types (lignite, bituminous coal, spruce, beech, and maize) in six different domestic heating appliances of various combustion designs. The effect of fuel as well as the effect of boiler type was studied. In total, 46 combustion runs were performed, during which numerous EFs were measured, including the EFs of particulate matter (PM), carbon monoxide, polyaromatic hydrocarbons (PAH), hexachlorobenzene (HxCBz), polychlorinated dibenzo-p-dioxins and furans (PCDD/F), etc. The highest EFs of nonchlorinated pollutants were measured for old-type boilers with over-fire and under-fire designs and with manual stoking and natural draft. Emissions of the above-mentioned pollutants from modern-type boilers (automatic, downdraft) were 10 times lower or more. The decisive factor for emission rate of nonchlorinated pollutants was the type of appliance; the type of fuel plays only a minor role. Emissions of chlorinated pollutants were proportional mainly to the chlorine content in fuel, but the type of appliance also influenced the rate of emissions significantly. Surprisingly, higher EFs of PCDD/F from combustion of chlorinated bituminous coal were observed for modern-type boilers (downdraft, automatic) than for old-type ones. On the other hand, when bituminous coal was burned, higher emissions of HxCBz were found for old-type boilers than for modern-type ones.     

Deacetylation of Arabinofuranosylated Xylopyranosyl Residues Related to Plant Xylan: Significant Differences Between Xylan Deacetylases Classified into Various Carbohydrate Esterase Families

A chemical synthesis of two novel phenyl glycosides of trisaccharides related to acetylarabinoxylan is described. The trisaccharides bear acetyl and arabinofuranosyl moieties at the non-reducing-end xylopyranosyl residue, which is substituted at positions 2 and 3. Both compounds were treated with various xylan deacetylases classified in different carbohydrate esterase (CE) families and significant differences between the families were found. While the arabinosylation hampers deacetylation by CE2-CE5 and CE12 family members, both epitopes are deesterified by CE1 and in particular CE6 enzymes. The 3-O-acetylated 2-O-arabinosylated compound is also processed by CE7 and majority of CE16 esterases, but not by a hitherto non-classified Flavobacterium johnsoniae acetylxylan esterase. The data suggests that a slow deesterification of the 2-O-acetylated 3-O-arabinosylated compound may be due to the acetyl group migration followed by deacetylation of this migration product.     

Electric Spark Sensitivity of Polynitro Compounds. Part V.A Relationship between Electric Spark and Impact Sensitivities of Energetic Materials（英）

ＩｎｔｒｏｄｕｃｔｉｏｎＡｗｉｄｅｓｐｅｃｔｒｕｍｏｆｔｈｅｅｆｆｅｃｔｓｉｎｖｏｌｖｅｄｉｎｄｉｃａｔｅｓｔｈａｔｔｈｅｒｅｗｉｌｌｂｅｐｒｏｂｌｅｍｓｉｎｆｏｒｍｕｌａｔｉｎｇａｕｎｉｑｕｅｍｏｄ ｅｌｏｆｍｅｃｈａｎｉｓｍｏｆｅｌｅｃｔｒｉｃｓｐａｒｋｉｎｉｔｉａｔｉｏｎｏｆｅｎｅｒｇｅｔｉｃｍａｔｅｒｉａｌｓ .Ｏｎｅｏｆｔｈｅｗａｙｓｏｆｓｐｅｃｉｆｉｃａｔｉｏｎｏｆｔｈｉｓｍｅｃｈ ａｎｉｓｍｃａｎｌｉｅｉｎｓｔｕｄｉｅｓｏｆｒｅｌａｔｉｏｎｓｈｉｐｓｏｆｔｈｅｓａｉｄｓｅｎｓｉ ｔｉ…     

A systematic study of tert-butylacrylamide-methyl acrylate-acrylic acid radical solution terpolymerization

Multi-functional polymers used for personal care products can be synthesized by radical polymerization of acrylic acid (AA) in alcohol/water solutions with non-functional monomers such as methyl acrylate (MA) and N-tert-butylacrylamide (t-BuAAm). However, solvents capable of forming or disrupting hydrogen bonds cause the polymerization kinetics of these monomers to deviate from their polymerization behaviour in bulk and non-polar solvents. In this work, a previous mechanistic model developed for MA/t-BuAAm copolymerization is extended to represent the terpolymerization system MA/t-BuAAm/AA. The additional kinetic coefficients required for the system are estimated from fitting to AA homopolymerizations and AA/MA and AA/t-BuAAm copolymerizations conducted in an ethanol/water solution. In-situ nuclear magnetic resonance (NMR) spectroscopy is used to follow monomer conversions and composition drift behaviour, with the molar mass distributions of the polymer products characterized by size-exclusion chromatography. Although AA is more reactive than MA in non-polar solvents, the reactivities of the two monomers equalize under the experimental conditions examined. Thus, the batch and semi-batch terpolymerization data collected are represented equally well by a reduced acrylate/t-BuAAm copolymerization model and the full terpolymerization implementation.