Ultrafast X-ray probing of water structure below the homogeneous ice nucleation temperature

Cryoprotectant-free thaumatin crystals have been cooled from 300 to 100 K at a rate of 0.1 K s−1– 103–104times slower than in conventional flash cooling – while continuously collecting X-ray diffraction data, so as to follow the evolution of protein lattice and solvent properties during cooling. Diffraction patterns show no evidence of crystalline ice at any temperature. This indicates that the lattice of protein molecules is itself an excellent cryoprotectant, and with sodium potassium tartrate incorporated from the 1.5 Mmother liquor ice nucleation rates are at least as low as in a 70% glycerol solution. Crystal quality during slow cooling remains high, with an average mosaicity at 100 K of 0.2°. Most of the mosaicity increase occurs above ∼200 K, where the solvent is still liquid, and is concurrent with an anisotropic contraction of the unit cell. Near 180 K a crossover to solid-like solvent behavior occurs, and on further cooling there is no additional degradation of crystal order. The variation ofBfactor with temperature shows clear evidence of a protein dynamical transition near 210 K, and at lower temperatures the slope dB/dTis a factor of 3–6 smaller than has been reported for any other protein. These results establish the feasibility of fully temperature controlled studies of protein structure and dynamics between 300 and 100 K.

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Cloud history can change water–ice–surface interactions of oxide mineral aerosols: a case study on silica

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-1075-2020 ◽

2020 ◽

Vol 20 (2) ◽

pp. 1075-1087 ◽

Cited By ~ 2

Author(s):

Ahmed Abdelmonem ◽

Sanduni Ratnayake ◽

Jonathan D. Toner ◽

Johannes Lützenkirchen

Keyword(s):

Surface Properties ◽

Second Harmonic ◽

Aerosol Particles ◽

Water Structure ◽

Cloud Droplet ◽

Ice Nucleation ◽

Nonlinear Spectroscopy ◽

Atmospheric Conditions ◽

Mineral Aerosols ◽

Interfacial Water Structure

Abstract. Mineral aerosol particles nucleate ice, and many insights have been obtained on water freezing as a function of mineral surface properties such as charge or morphology. Previous studies have mainly focused on pristine samples despite the fact that aerosol particles age under natural atmospheric conditions. For example, an aerosol-containing cloud droplet can go through freeze–melt or evaporation–condensation cycles that change the surface structure, the ionic strength, and pH. Variations in the surface properties of ice-nucleating particles in the atmosphere have been largely overlooked. Here, we use an environmental cell in conjunction with nonlinear spectroscopy (second-harmonic generation) to study the effect of freeze–melt processes on the aqueous chemistry at silica surfaces at low pH. We found that successive freeze–melt cycles disrupt the dissolution equilibrium, substantially changing the surface properties and giving rise to marked variations in the interfacial water structure and the ice nucleation ability of the surface. The degree of order of water molecules, next to the surface, at any temperature during cooling decreases and then increases again with sample aging. Along the aging process, the water ordering–cooling dependence and ice nucleation ability improve continuously.

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Coal fly ash: linking immersion freezing behavior and physicochemical particle properties

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-13903-2018 ◽

2018 ◽

Vol 18 (19) ◽

pp. 13903-13923 ◽

Cited By ~ 15

Author(s):

Sarah Grawe ◽

Stefanie Augustin-Bauditz ◽

Hans-Christian Clemen ◽

Martin Ebert ◽

Stine Eriksen Hammer ◽

...

Keyword(s):

Fly Ash ◽

Single Particle ◽

Coal Fly Ash ◽

Ice Nucleation ◽

Freezing Behavior ◽

Cloud Droplets ◽

X Ray ◽

Particle Properties ◽

Cold Stage ◽

Immersion Freezing

Abstract. To date, only a few studies have investigated the potential of coal fly ash particles to trigger heterogeneous ice nucleation in cloud droplets. The presented measurements aim at expanding the sparse dataset and improving process understanding of how physicochemical particle properties can influence the freezing behavior of coal fly ash particles immersed in water. Firstly, immersion freezing measurements were performed with two single particle techniques, i.e., the Leipzig Aerosol Cloud Interaction Simulator (LACIS) and the SPectrometer for Ice Nuclei (SPIN). The effect of suspension time on the efficiency of the coal fly ash particles when immersed in a cloud droplet is analyzed based on the different residence times of the two instruments and employing both dry and wet particle generation. Secondly, two cold-stage setups, one using microliter sized droplets (Leipzig Ice Nucleation Array) and one using nanoliter sized droplets (WeIzmann Supercooled Droplets Observation on Microarray setup) were applied. We found that coal fly ash particles are comparable to mineral dust in their immersion freezing behavior when being dry generated. However, a significant decrease in immersion freezing efficiency was observed during experiments with wet-generated particles in LACIS and SPIN. The efficiency of wet-generated particles is in agreement with the cold-stage measurements. In order to understand the reason behind the deactivation, a series of chemical composition, morphology, and crystallography analyses (single particle mass spectrometry, scanning electron microscopy coupled with energy dispersive X-ray microanalysis, X-ray diffraction analysis) were performed with dry- and wet-generated particles. From these investigations, we conclude that anhydrous CaSO4 and CaO – which, if investigated in pure form, show the same qualitative immersion freezing behavior as observed for dry-generated coal fly ash particles – contribute to triggering heterogeneous ice nucleation at the particle–water interface. The observed deactivation in contact with water is related to changes in the particle surface properties which are potentially caused by hydration of CaSO4 and CaO. The contribution of coal fly ash to the ambient population of ice-nucleating particles therefore depends on whether and for how long particles are immersed in cloud droplets.

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Characterization of aerosol particles at Cabo Verde close to sea level and at the cloud level – Part 2: Ice-nucleating particles in air, cloud and seawater

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-1451-2020 ◽

2020 ◽

Vol 20 (3) ◽

pp. 1451-1468 ◽

Cited By ~ 4

Author(s):

Xianda Gong ◽

Heike Wex ◽

Manuela van Pinxteren ◽

Nadja Triesch ◽

Khanneh Wadinga Fomba ◽

...

Keyword(s):

Sea Level ◽

Cloud Water ◽

Ice Nucleation ◽

Cape Verde ◽

Nucleation Temperature ◽

Sea Spray ◽

Cloud Droplets ◽

Cabo Verde ◽

Active Particles ◽

Sea Surface Microlayer

Abstract. Ice-nucleating particles (INPs) in the troposphere can form ice in clouds via heterogeneous ice nucleation. Yet, atmospheric number concentrations of INPs (NINP) are not well characterized, and, although there is some understanding of their sources, it is still unclear to what extend different sources contribute or if all sources are known. In this work, we examined properties of INPs at Cabo Verde (a.k.a. Cape Verde) from different environmental compartments: the oceanic sea surface microlayer (SML), underlying water (ULW), cloud water and the atmosphere close to both sea level and cloud level. Both enrichment and depletion of NINP in SML compared to ULW were observed. The enrichment factor (EF) varied from roughly 0.4 to 11, and there was no clear trend in EF with ice-nucleation temperature. NINP values in PM10 sampled at Cape Verde Atmospheric Observatory (CVAO) at any particular ice-nucleation temperature spanned around 1 order of magnitude below −15 ∘C, and about 2 orders of magnitude at warmer temperatures (>-12 ∘C). Among the 17 PM10 samples at CVAO, three PM10 filters showed elevated NINP at warm temperatures, e.g., above 0.01 L−1 at −10 ∘C. After heating samples at 95 ∘C for 1 h, the elevated NINP at the warm temperatures disappeared, indicating that these highly ice active INPs were most likely biological particles. INP number concentrations in PM1 were generally lower than those in PM10 at CVAO. About 83±22 %, 67±18 % and 77±14 % (median±standard deviation) of INPs had a diameter >1 µm at ice-nucleation temperatures of −12, −15 and −18 ∘C, respectively. PM1 at CVAO did not show such elevated NINP at warm temperatures. Consequently, the difference in NINP between PM1 and PM10 at CVAO suggests that biological ice-active particles were present in the supermicron size range. NINP in PM10 at CVAO was found to be similar to that on Monte Verde (MV, at 744 m a.s.l.) during noncloud events. During cloud events, most INPs on MV were activated to cloud droplets. When highly ice active particles were present in PM10 filters at CVAO, they were not observed in PM10 filters on MV but in cloud water samples instead. This is direct evidence that these INPs, which are likely biological, are activated to cloud droplets during cloud events. For the observed air masses, atmospheric NINP values in air fit well to the concentrations observed in cloud water. When comparing concentrations of both sea salt and INPs in both seawater and PM10 filters, it can be concluded that sea spray aerosol (SSA) only contributed a minor fraction to the atmospheric NINP. This latter conclusion still holds when accounting for an enrichment of organic carbon in supermicron particles during sea spray generation as reported in literature.

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Water Structure and Dynamics in Smectites: X-ray Diffraction and 2H NMR Spectroscopy of Mg–, Ca–, Sr–, Na–, Cs–, and Pb–Hectorite

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.6b03431 ◽

2016 ◽

Vol 120 (16) ◽

pp. 8863-8876 ◽

Cited By ~ 24

Author(s):

U. Venkateswara Reddy ◽

Geoffrey M. Bowers ◽

Narasimhan Loganathan ◽

Mark Bowden ◽

A. Ozgur Yazaydin ◽

...

Keyword(s):

Nmr Spectroscopy ◽

Water Structure ◽

2H Nmr ◽

X Ray Diffraction ◽

X Ray ◽

2H Nmr Spectroscopy ◽

Structure And Dynamics

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Two-Step Freezing Procedure for Cryopreservation of Rumen Ciliates, an Effective Tool for Creation of a Frozen Rumen Protozoa Bank

Applied and Environmental Microbiology ◽

10.1128/aem.69.7.3826-3832.2003 ◽

2003 ◽

Vol 69 (7) ◽

pp. 3826-3832 ◽

Cited By ~ 15

Author(s):

E. Nsabimana ◽

S. Kišidayová ◽

D. Macheboeuf ◽

C. J. Newbold ◽

J. P. Jouany

Keyword(s):

Liquid Nitrogen ◽

Ice Nucleation ◽

Slow Freezing ◽

Nucleation Temperature ◽

Subzero Temperature ◽

Equilibration Time ◽

Rumen Protozoa ◽

Ciliate Species ◽

Freezing Procedure ◽

Holding Temperature

ABSTRACT The present study aimed at the long-term storage of rumen protozoa as living cells in liquid nitrogen. The two-step or interrupted slow freezing procedure was used to cryopreserve six of the dominant species of rumen ciliates isolated from monofaunated animals, Dasytricha ruminantium, Entodinium caudatum, Epidinium ecaudatum caudatum, Eudiplodinium maggii, Isotricha prostoma, and Polyplastron multivesiculatum. We optimized the first step in the interrupted slow freezing procedure, from the extracellular ice nucleation temperature to the holding temperature, and studied the effects of the cooling rates on survival. In addition to the nature of the cryoprotectant (dimethyl sulfoxide), the equilibration temperature and equilibration time (25°C and 5 min, respectively), and the holding time at subzero temperature (45 min) recommended previously (S. Kišidayová, J. Microbiol. Methods 22:185-192, 1995), we found that a holding temperature of −30°C, a cooling rate from extracellular ice nucleation temperature to holding temperature of between 1.2°C/min and 2.5°C/min, depending on the ciliate, and rumen juice as the freezing and thawing medium markedly improved the survival rate. Survival rates determined after 2 weeks in liquid nitrogen were 100% for Isotricha, 98% for Dasytricha, 85% for Epidinium, 79% for Polyplastron, 63% for Eudiplodinium, and 60% for Entodinium. They were not significantly modified after a period of 1 year in liquid nitrogen. Four of the five ciliate species cryopreserved for 8 months in liquid nitrogen successfully colonized the rumen when inoculated into defaunated animals. These results have made it possible to set up a bank of cryopreserved rumen protozoa.

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