English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

This work presents experimental data of the temperaturedependence of water activity in aqueous organic solutions relevant fortropospheric conditions (200–273 K). Water activity (aw) at lowtemperatures (T) is a crucial parameter for predicting homogeneous icenucleation. We investigated temperature-dependent water activities, icefreezing and melting temperatures of solutions, and vapour pressures of aselection of atmospherically relevant aqueous organic systems. To measureaw over a wide composition range and with a focus on lowtemperatures, we use various aw measurement techniques andinstruments: a dew point water activity meter, an electrodynamic balance(EDB), differential scanning calorimetry (DSC), and a setup to measure thetotal gas phase pressure at equilibrium over aqueous solutions. Wateractivity measurements were performed for aqueous multicomponent andmultifunctional organic mixtures containing the functional groups typicallyfound in atmospheric organic aerosols, such as hydroxyl, carboxyl, ketone,ether, ester, and aromatic groups. The aqueous organic systems studied atseveral fixed compositions over a considerable temperature range differsignificantly in their temperature dependence. Aqueous organic systems of1,4-butanediol and methoxyacetic acid show a moderate decrease inaw with decreasing temperature. The aqueous M5 system (amulticomponent system containing five different dicarboxylic acids) andaqueous 2-(2-ethoxyethoxy)ethanol solutions both show a strong increase ofwater activity with decreasing temperature at high solute concentrations forT < 270 K and T < 260 K, respectively. These measurements showthat the temperature trend of aw can be reversed at lowtemperatures and that linear extrapolations of high-temperature data may leadto erroneous predictions. To avoid this, experimentally determinedaw at low temperature are needed to improve thermodynamic modelstowards lower temperatures and for improved predictions of the ice nucleationability of organic–water systems

Experimental determination of the temperature dependence of water activities for a selection of aqueous organic solutions