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13. |
- Eriksson, Axel, et al.
(author)
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Diesel soot aging in urban plumes within hours under cold dark and humid conditions
- 2017
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322.
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Journal article (peer-reviewed)abstract
- Fresh and aged diesel soot particles have different impacts on climate and human health. While fresh diesel soot particles are highly aspherical and non-hygroscopic, aged particles are spherical and hygroscopic. Aging and its effect on water uptake also controls the dispersion of diesel soot in the atmosphere. Understanding the timescales on which diesel soot ages in the atmosphere is thus important, yet knowledge thereof is lacking. We show that under cold, dark and humid conditions the atmospheric transformation from fresh to aged soot occurs on a timescale of less than five hours. Under dry conditions in the laboratory, diesel soot transformation is much less efficient. While photochemistry drives soot aging, our data show it is not always a limiting factor. Field observations together with aerosol process model simulations show that the rapid ambient diesel soot aging in urban plumes is caused by coupled ammonium nitrate formation and water uptake.
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- Eriksson, Axel, et al.
(author)
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Particulate PAH Emissions from Residential Biomass Combustion : Time-Resolved Analysis with Aerosol Mass Spectrometry
- 2014
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 48:12, s. 7143-7150
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Journal article (peer-reviewed)abstract
- Time-resolved emissions of particulate polycyclic aromatic hydrocarbons (PAHs) and total organic particulate matter (OA) from a wood log stove and an adjusted pellet stove were investigated with high-resolution time-of-flight aerosol mass spectrometry (AMS). The highest OA emissions were found during the addition of log wood on glowing embers, that is, slow burning pyrolysis conditions. These emissions contained about 1% PAHs (of OA). The highest PAH emissions were found during fast burning under hot air starved combustion conditions, in both stoves. In the latter case, PAHs contributed up to 40% of OA, likely due to thermal degradation of other condensable species. The distribution of PAHs was also shifted toward larger molecules in these emissions. AMS signals attributed to PAHs were found at molecular weights up to 600 Da. The vacuum aerodynamic size distribution was found to be bimodal with a smaller mode (Dva ~ 200 nm) dominating under hot air starved combustion and a larger sized mode dominating under slow burning pyrolysis (Dva ~ 600 nm). Simultaneous reduction of PAHs, OA and total particulate matter from residential biomass combustion may prove to be a challenge for environmental legislation efforts as these classes of emissions are elevated at different combustion conditions.
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17. |
- Folkesdotter, Gärd, et al.
(author)
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Byggdag för allmänheten i Gävle
- 1978
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In: Kulturminnesvård. - Stockholm : Riksantikvarieämbetet. - 0346-9077. ; :3, s. 40-45
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Journal article (pop. science, debate, etc.)abstract
- Arkitektcentrum och länsmuseet i Gävle ordnade i mars en byggdag - eller rättare byggnadsvårdsdag -på museet med hjälp av stadsarkitekt-och fastighetskontoren i Gävle karrmun och Statens institut för byggnadsforskning (san flyttade till Gävle 1976). Cm arrangemanget, som blev en stor framgång med över 1000 besökande, skriver här Gärd Folkesdotteroch Erik Nordin.
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18. |
- Högberg, Hans-Erik, et al.
(author)
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Biocatalysis as a useful tool in pheromone synthesis. Enantiomerically pure building blocks from baker's yeast reductions and enzyme catalysed resoluti
- 1994
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In: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 22:3, s. 591-606
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Journal article (peer-reviewed)abstract
- Biocatalytical methods are presented which provide useful building blocks for pheromone synthesis. Examples of the utility of this approach are the preparation of building blocks for the synthesis of stereochemically pure isomers of pine sawfly pheromones and some other pheromones. Enantiom- erically pure ( 98% ee) 2-methyl-1-alkanols 2 were obtained via baker's yeast reduction of suitable α,β-unsaturated aldehydes, and by using lipases from Pseudomonas to effect resolution by transesterification of suitable racemic precursors to 2-methyl-1-alkanols 2 which gave high enantiomeric ratios E > 100. The resolution by esterification mediated by lipase from Candida rugosa of racemic 2-methylalkanoic acids also gave high enantiomeric ratios E> 100 after having improved the reaction conditions by regulating water activity, by choice of the appropriate complimentary substrate alcohol and by adjusting the initial equivalents of the latter present at the start. Also discussed is the separation of diastereomers of diprionol 1, which is naturally occurring in the pine sawfly Neodiprion sertifer, where it is the direct precursor of its pheromone.
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