Abstract. For efficient analysis and characterization of biological ice nuclei under
immersion freezing conditions, we developed the Twin-plate Ice Nucleation Assay
(TINA) for high-throughput
droplet freezing experiments, in which the temperature profile and freezing
of each droplet is tracked by an infrared detector. In the fully automated
setup, a couple of independently cooled aluminum blocks carrying two 96-well
plates and two 384-well plates, respectively, are available to study ice
nucleation and freezing events simultaneously in hundreds of microliter-range
droplets (0.1–40 µL). A cooling system with two refrigerant
circulation loops is used for high-precision temperature control (uncertainty
<0.2 K), enabling measurements over a wide range of temperatures
(∼ 272–233 K) at variable cooling rates (up to 10 K min−1). The TINA instrument was tested and characterized in experiments with
bacterial and fungal ice nuclei (IN) from Pseudomonas syringae (Snomax®) and Mortierella alpina, exhibiting freezing curves in good agreement with literature
data. Moreover, TINA was applied to investigate the influence of chemical
processing on the activity of biological IN, in particular the effects of
oxidation and nitration reactions. Upon exposure of
Snomax® to O3 and NO2, the cumulative
number of IN active at 270–266 K decreased by more than 1 order of
magnitude. Furthermore, TINA was used to study aqueous extracts of
atmospheric aerosols, simultaneously investigating a multitude of samples
that were pre-treated in different ways to distinguish different kinds of
IN. For example, heat treatment and filtration indicated that most
biological IN were larger than 5 µm. The results confirm that TINA is
suitable for high-throughput experiments and efficient analysis of
biological IN in laboratory and field samples.
Abstract. For efficient analysis and characterization of biological ice nuclei under immersion freezing conditions, we developed a Twin-plate Ice Nucleation Assay (TINA) for high-throughput droplet freezing experiments, in which the temperature gradient and freezing of each droplet is tracked by an infrared detector. In the fully automated setup, a couple of independently cooled aluminum blocks carrying two 96-well plates and two 384-well plates, respectively, are available to study ice nucleation and freezing events simultaneously in hundreds of microliter range droplets (0.1–40 µL). A cooling system with two refrigerant circulation loops is used for high-precision temperature control (deviations
Abstract. The dynamic processing of aerosols in the atmosphere is difficult to mimic under laboratory conditions, particularly on a single-particle level with high spatial and chemical resolution. Our new microreactor system for X-ray microscopy facilitates observations under in situ conditions and extends
the accessible parameter ranges of existing setups to very high humidities and low temperatures. With the parameter margins for pressure (180–1000 hPa), temperature (∼250 K to room temperature), and relative humidity (∼0 % to above 98 %), a wide range of tropospheric conditions is covered. Unique features are the mobile design and compact size that make the instrument applicable to different synchrotron facilities. Successful first experiments were conducted at two X-ray microscopes, MAXYMUS, located at beamline UE46 of the synchrotron BESSY II, and PolLux, located at beamline X07DA of the Swiss Light Source in the Paul Scherrer Institute. Here we present the design and analytical scope of the system, along with first results from hydration–dehydration experiments on ammonium sulfate and potassium sulfate particles and the tentative observation of water ice at low temperature and high relative humidity in a secondary organic aerosol particle from isoprene oxidation.
Figure S1. Screenshot of the T and RH control panel in the graphical user interface, emphasizing the cooling capacities of the setup. Please note that the sensor values shown here are uncalibrated. The actual microreactor temperature is at about −23 • C.
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