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| Titel |
A new electrodynamic balance (EDB) design for low-temperature studies: application to immersion freezing of pollen extract bioaerosols |
| VerfasserIn |
H.-J. Tong, B. Ouyang, N. Nikolovski, D. M. Lienhard, F. D. Pope, M. Kalberer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 3 ; Nr. 8, no. 3 (2015-03-10), S.1183-1195 |
| Datensatznummer |
250116209
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| Publikation (Nr.) |
 copernicus.org/amt-8-1183-2015.pdf |
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| Zusammenfassung |
| In this paper we describe a newly designed cold electrodynamic balance(CEDB)
system, built to study the evaporation kinetics and freezing
properties of supercooled water droplets. The temperature of the CEDB
chamber at the location of the levitated water droplet can be controlled in
the range −40 to +40 °C, which is achieved using
a combination of liquid nitrogen cooling and heating by positive temperature
coefficient heaters. The measurement of liquid droplet radius is obtained by
analysing the Mie elastic light scattering from a 532 nm laser. The Mie
scattering signal was also used to characterise and distinguish droplet
freezing events; liquid droplets produce a regular fringe pattern, whilst the
pattern from frozen particles is irregular. The evaporation rate of singly
levitated water droplets was calculated from time-resolved measurements of
the radii of evaporating droplets and a clear trend of the evaporation rate
on temperature was measured. The statistical freezing probabilities of
aqueous pollen extracts (pollen washing water) are obtained in the
temperature range −4.5 to −40 °C. It was found that that pollen
washing water from water birch (Betula fontinalis occidentalis) pollen can act as ice nuclei in the
immersion freezing mode at temperatures as warm as −22.45 (±0.65) °C.
Furthermore it was found that the protein-rich component of
the washing water was significantly more ice-active than the
non-proteinaceous component. |
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