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Lee, JiYi,Lane, Douglas A. Elsevier 2010 Atmospheric environment Vol.44 No.20
<P><B>Abstract</B></P><P>The reaction of gas phase phenanthrene (Phen) with the OH radical in the presence of NO<SUB>x</SUB> was studied in a reaction chamber. A number of oxidation products were identified by two dimensional gas chromatography–time of flight mass spectrometry (GC × GC–TOFMS). Identified products included 9-fluorenone, 1,2-naphthalic anhydride, 2,2′-diformylbiphenyl, dibenzopyranone, 1, 2, 3, 4 and 9-phenanthrols, 2, 3, 4 and 9-nitrophenanthrenes, 1,4-phenanthrenequinone, 9,10-phenanthrenequinone, and 2- and 4-nitrodibenzopyranones. This is the first study to identify 1,2-naphthalic anhydride and 1,4-phenanthrenequinone as products of the gas phase reaction of Phen with the OH radical. Eight more products were tentatively identified by their mass spectral fragmentation patterns and based on the typical OH radical initiated photochemical reaction mechanisms of simple aromatic compounds and naphthalene. In the reaction chamber, particle formation of products as a function of irradiation time was measured. Phenanthrenequinones, phenanthrol, nitrophenanthrene and nitrobenzopyranone were observed predominantly in the particle phase. This implies that these oxidized products formed from the reaction of Phen with the OH radical in the chamber would be associated with particles in the atmosphere and may, therefore, have an impact on human health. Possible pathways for the formation of these products are suggested and discussed.</P>
Lee, Ji Yi,Lane, Douglas A.,Kim, Yong Pyo CSIRO Publishing 2015 Environmental chemistry Vol.12 No.3
<P> Environmental context Atmospheric quinones present a potential toxic risk to human health because of their involvement in the generation of reactive oxygen species. Gas phase reactions of naphthalene and phenanthrene with the OH radical are investigated in a laboratory reaction chamber to provide a preliminary assessment of the importance of the atmospheric formation of quinones. Abstract In light of the potential toxicity of quinones (QNs) to human health, previous studies carried out measurement of QNs in ambient air samples and from motor vehicle emissions to understand the characteristics and the sources of QNs in the atmosphere. The major compounds observed in the ambient air samples comprised two and three benzene rings and included polyaromatic hydrocarbon (PAH)-quinones (PAH-QNs) such as 1,2-naphthoquinone (1,2-NQ), 1,4-naphthoquinone (1,4-NQ), 9,10-phenanthrenequinone (9,10-PQ) and 9,10-anthraquinone (9,10-AQ). Although these PAH-QNs are found in vehicular emissions, they may also be formed by the photochemical reactions of gas phase PAHs with atmospheric oxidants. In this study, to allow an assessment of the importance of the atmospheric formation of PAH-QNs and to understand more clearly the sources of PAH-QNs in the atmosphere, the formation yields of PAH-QNs from the gas phase reactions of naphthalene and phenanthrene with the OH radical were observed in a laboratory reaction chamber. In addition, the phase distribution of the PAH-QNs was determined. For naphthoquinones (NQs), the formation yields of 1,4-NQ and 1,2-NQ were 1.5±0.4 and 5.1±2.7% respectively. The measured yields of PQs were 3.6±0.8% for 9,10-PQ and 2.7±1.1% for 1,4-PQ. From the measured yield data, the atmospheric formation of PAH-QNs was estimated and the importance of the atmospheric formation of PAH-QNs from the gas phase reaction of PAHs with the OH radical is discussed. </P>
Park, G.,Koo, B.-C.,Gibson, S. J.,Kang, J.-h.,Lane, D. C.,Douglas, K. A.,Peek, J. E. G.,Korpela, E. J.,Heiles, C.,Newton, J. H. IOP Publishing 2013 The Astrophysical journal Vol.777 No.1
<P>We search for fast-expanding Hi shells associated with Galactic supernova remnants (SNRs) in the longitude range l approximate to 32 degrees to 77 degrees using 21 cm line data from the Inner-Galaxy Arecibo L-band Feed Array (I-GALFA) Hi survey. Among the 39 known Galactic SNRs in this region, we find such Hi shells in 4 SNRs: W44, G54.4-0.3, W51C, and CTB 80. All four were previously identified in low-resolution surveys, and three of those (excluding G54.4-0.3) were previously studied with the Arecibo telescope. A remarkable new result, however, is the detection of Hi emission at both very high positive and negative velocities in W44 from the receding and approaching parts of the Hi expanding shell, respectively. This is the first detection of both sides of an expanding shell associated with an SNR in H I 21 cm emission. The high-resolution I-GALFA survey data also reveal a prominent expanding Hi shell with high circular symmetry associated with G54.4-0.3. We explore the physical characteristics of four SNRs and discuss what differentiates them from other SNRs in the survey area. We conclude that these four SNRs are likely the remnants of core-collapse supernovae interacting with a relatively dense (greater than or similar to 1 cm(-3)) ambient medium, and we discuss the visibility of SNRs in the H I 21 cm line.</P>