374 research outputs found
Physical properties and processes of secondary organic aerosol and its constituents
No full textAtmospheric aerosol particles are involved in several important processes including the formation of clouds and precipitation. A considerable fraction of the ambient aerosol mass consists of organic compounds of both primary and secondary origin. These organic compounds are often semi-volatile and susceptible to oxidation which makes the organic aerosol a dynamic system, both chemically and physically. Once an aerosol is formed or released into the atmosphere, several processes will begin to alter its chemical and physical properties.
The focus of the work presented in this thesis has been to use experimental methods to characterise single aerosol components and more complex experimental systems, involving the formation and processing of secondary organic aerosol (SOA). The volatility of aerosol particles, e.g. the evaporation rate of the particles upon heating, can provide information of several important properties. From an aerosol consisting only of one pure compound it is possible to derive physical quantities like saturation vapour pressure and enthalpy of evaporation. In more complex systems like a secondary organic aerosol the volatility can give information about changes in composition, state of oxidation and degree of internal or external mixing.
With the use of a volatility tandem differential mobility analyser (VTDMA), the saturation vapour pressures and enthalpies of evaporation have been determined for pure compounds that are known constituents of ambient aerosol samples i.e. nine carboxylic acids. Two of them were cyclic, pinic and pinonic acid and seven of them were straight chain dicarboxylic acids with number of carbons ranging from C4 to C10. These properties were in addition evaluated for the aminium nitrates of mono-, di-, and trimethylamine, ethyl- and monoethanolamine. The calculated saturation vapour pressures for the carboxylic acids were in the range of 10-6 to 10-3 Pa and the determined enthalpies of evaporation ranged from 83 to 161 kJ mol-1. The corresponding values for the aminium nitrates were for the calculated saturation vapour pressures approximately 10-4 Pa and for the enthalpies of evaporation 54 to 72 kJ mol-1.
The VTDMA system has also been utilised to characterise SOA formed in the AIDA and SAPHIRE smog chambers from the ozonolysis of α-pinene and limonene and the change in the SOA thermal properties during OH radical induced ageing. Further, the effect of elevated ozone concentration and radical chemistry on SOA formed from limonene ozonolysis in the G-FROST laminar flow reactor was investigated. In addition, to compare with vapour pressures of aminium nitrates SOA generated from photooxodation of alkyl amines have been characterised in the EUPHORE smog chamber.
The calculated vapour pressures of all the investigated pure compounds in this work characterise them to be in the semi-volatile organic compound (SVOC) category; hence they will be present both in the gaseous and condensed phase in the atmosphere. This implied that all these compounds will be susceptible for gas phase OH radical oxidation that was demonstrated to be an important process for the complex mixtures investigated in the smog chamber facilities. The OH chemistry was also influencing the volatility of aerosol produced in G-FROST by ozonlysis. Regarding photooxodation of amines the aerosols produced under high NOx conditions initially mimicked the pure salts but was efficiently transformed by oxidation into an aerosol with similar volatility properties as observed in the terpene oxidation experiments
Laboratory simulations of benzene oxidation and formation of highly oxygenated organic molecules (HOM)
No full textThis dataset supplements the following manuscript:
Garmash, O., Rissanen, M. P., Pullinen, I., Schmitt, S., Kausiala, O., Tillmann, R., Percival, C., Bannan, T. J., Priestley, M., Hallquist, Å. M., Kleist, E., Kiendler-Scharr, A., Hallquist, M., Berndt, T., McFiggans, G., Wildt, J., Mentel, T., and Ehn, M.: Multi-generation OH oxidation as a source for highly oxygenated organic molecules from aromatics, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2019-582, in review, 2019.
It presents data from Table 1, Tables S1-S4 and Figures 5, A1 and A2, including model input data.</p
Formation, ageing and thermal properties of secondary organic aerosol
No full textIn order to properly represent and predict the effects of aerosol in climate systems, an accurate description of their formation and properties is needed. This thesis describes work done to increase the knowledge of processes and properties of atmospherically relevant secondary organic aerosol (SOA) from both biogenic and anthropogenic origin. The common theme for these projects is the use of a Volatility Tandem Differential Mobility Analyser (VTDMA) setup, which in combination with other observations has generated insight into both detailed chemical mechanisms and physical processes that eventually could be suitable for testing in air quality or climate models. During the course of this work, the experimental facility
the Gothenburg Flow Reactor for Oxidation Studies at low Temperatures (G-FROST) and
the VTDMA setup, as well as a corresponding data evaluation methodology, have been
improved and refined.
Thermal properties could be linked to both formation and ageing processes of SOA. Using
a VTDMA setup, where the thermal characteristics of SOA were measured at a range of
evaporation temperatures, a sigmoidal fit to the data enabled parameterisation of their
volatility properties. The parameters extracted were e.g. the temperature corresponding to
a volume fraction remaining of 0.5 (TVFR0.5) and the slope factor (SVFR), which are measures
of the general volatility and the volatility distribution of the condensed phase products,
respectively. A higher TVFR0.5 indicates lower volatility, while an increase of SVFR states a
broader distribution of vapour pressures. The response of these parameters from changes in
experimental conditions could be linked to processes occurring both in the gaseous and the
condensed phase. In photo-chemical experiments, the change in TVFR0.5 and SVFR could be
described using the OH dose.
The gas phase processes were found to be very important for SOA ageing, driven mainly by
OH radical exposure in the outdoor chamber SAPHIR. However, processes in the condensed
phase, such as plausible non oxidative ageing processes and non-liquid behaviour of SOA
particles, were also observed.
Detailed studies of ozonolysis of the boreal forest monoterpenes β-pinene and limonene were
enabled by precise control of reaction conditions using the G-FROST. The experimental
findings in response to e.g. water and radical conditions emphasized the difference in
ozonolysis reaction paths between endo- and exocyclic compounds. The results support
the recently suggested decomposition of the stabilized Criegee Intermediate via the
hydroperoxide channel in ozonolysis of β-pinene
A Study on Norwegian Consumers´ Attitudes towards H&M´s Designer Collaborations in the High Street Retail Market, and the consumers´ purchase intention.
No full textH&M has since 2004 gone into partnership with a different fashion designer each year, and produces a limited edition Designer collaboration collection. The three components of attitude, affective, cognitive and behavioural were applied to measure consumers\u92 attitude towards H&M Designer collaborations, and the consumer purchase intention. The Likert scale was adopted to measure the consumers\u92 answers regarding the different attitude components, and the affect they have on attitude development. H&M was selected since it has a long tradition in Norway, opening the first store in 1964. Furthermore, H&M have a lot of loyal and satisfied customer in Norway (NKB Results, 2014). A quantitative nonprobability-sampling questionnaire collected 115 respondents. The relationship between the attitude components was analysed via Pearson Correlation in SPSS.
The investigation demonstrated a relationship between the attitudes components. It showed that the consumers\u92 attitudes towards H&M Designer collaboration are somewhat negative. There is a high knowledge about the Designer collaborations, but minimal purchase intentions. A lot of the consumers feel the collections are too expensive, and in some cases quite odd. However, the consumers seem to like to concept, but consumers´ struggle to match the expensive prices and H&M
De elegiaci apud Romanos carminis elegantiis expositio cujus partem secundam ... Mag. Andreas Hedner ... et Johannes Hallquist stip. Palmberg. Sudermanno-Nericius. In Audit. Gustav. die XXVIII Maji. MDCCCXXXI. H. A. M. S., p. 2 [Elektronisk resurs]
No full textRecommended from our members
Men's Cross Country team, 1973
No full textFront Row: R. Danurand, J. Osowski, D. Long, N. Wright, B. Belliveau, R. LaFreniere, R. Mandevill, A. Hallquist, P. Graffey, D. Legnard; Second Row- S. Sweeney, C. Keenan, R. Newhouse, D. Fowler, A. Briggs, A. Vogt, J. Wnek, M. Schesser, C. Owne, A. Richard; Back Row: M. Severino, Asst. Coach A. Hoffman, K. Lutgens, M. Koronkowicz, A. Clark, Mgr. J. Fitzpatrick, Coach F. Sanell
Recommended from our members
Varsity Men's Track team, 1974
No full textFront Row- S. Silva, A. Briggs, T. Lee, R. Donle, P. Varadian, J. McKenzie, J. Webber, A. Hallquist, J. Hatch, H. Fitzgerald, J. Wnek, C. Keenan, K. Osborne, D. Nygaard; Back Row- Coach M. Norcross, C. Siegal (Mgr), M. Clorite, L. Sunderlin, J. Smith, C. Baker, D. Orenstein, K. Lutgens, E. Wiles, J. Howe, R. Pomeroy, R. Newhouse, R. Baker, D. Gibbons, P. Kane, C. Owen, T. McAloon, J. Albernaz, J. Osowski (Mgr
Recommended from our members
Men's Cross Country team, 1972
No full textFront Row: C. Keenan, R. Fillippetti, A. Murch, M. Weisman, A. Hallquist; Second Row: R. Stockdale, R. Ferrari, R. Newhouse, R. Mandeville, R. Filanowicz, Coach Sanella; Third Row: S. Rubin, A. Briggs, R. LaFrenieve, E. McAniff, J. Wnek, A. Hoffman, Asst. Coach; Back Row: G. Gingeras, J. Fitzpatrick, Asst. Mgr. A Vogt, J. Franso
Recommended from our members
Varsity Men's Track team, 1972
No full textBack Row- C. Kenan, D. Fowler, D. Grover, K. Lutgens, R. Donle, D. Eves, J. Leather, J. McKenzie; Second Row- Coach R. Heikkinen, V. Kruczynski, B. Arey, M. Weisman, W. Komm, P. Varadian, J. Strempek, A. Hallquist, E. Wiles, T. Ferguson, T. Beckman, J. Weber, T. Fieldsend, M. Kosmo, R. Newhouse, F. Sundermeyer, P. Rojko, Coach Norcross, Coach Herrion; Front ROw- H. Fitzgerald, P. DeMeo, W. Rutherford, A. Murch, Tri-Capt( M. Hoyt, J. Andruchow, M. DuPuis), R. Zepp, J. Franson, T. Lee, R. Mathews, J. Hatc
Recommended from our members
Varsity Men's Track team, 1973
No full textFront Row- J. Smith, W. Komm, M. Graham, J. Webber, R. Allen, A. Hallquist, J. Franson, T. Beckman, A. Murch, S. Slavick, G. Dunn, T. Ferguson, R. Stockdale, R. Donle, D. Fowler, E. Wright, S. McKenzie; Back Row- R. Mathews (Mgr), Coach Norcross, N. Wright, S. Silva, J. Hatch, C. Keenan, P. Selent, S. Yankum, J. Leather, T. Lee, K. Lutgens, A. Briggs, S. Walz, T. McAloon, P. Varadian, S. Manzi, K. Osborne, D. Nygaard, S. Fitzpatrick (Mgr
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