Location and quantitative aspects of ice nucleators in insects

1968 ◽  
Vol 46 (3) ◽  
pp. 329-333 ◽  
Author(s):  
R. W. Salt
Keyword(s):  
Freezing Temperature ◽  
Ice Nucleation ◽  
Gut Contents ◽  
Aqueous Systems ◽  
Nucleation Sites ◽  
Ice Nucleators

Gut contents are the source of ice nucleation in feeding insects; in those non-feeding forms where it has been possible to observe nucleation, residual food within the gut has been the source. When freezing is confined to tissues with no digestive elements, such as excised appendages, preferred nucleation sites may be observed but the tissues or structures involved have not been identified. Haemolymph and intracellular matter are improbable as functional nucleating sites, reducing the anatomical possibilities greatly.Isolated appendages were also used to demonstrate that the relation between freezing temperature and mass in aqueous systems is more accurately defined by the numbers or other quantitative aspects of nucleators than by the mass of water.

Relation between freezing temperature and length of conifer needles

1968 ◽  
Vol 46 (10) ◽  
pp. 1211-1213 ◽  
Author(s):  
Shosuke Kaku ◽  
R.W. Salt
Keyword(s):  
Water Content ◽  
Cell Walls ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Nucleation Temperature ◽  
Nucleation Sites ◽  
Conifer Needles ◽  
Increasing Function

The relationships between freezing temperature (or supercooling) and length, weight, and water content of Pinus and Cedrus needles were investigated. Freezing temperature was an increasing function of each of these three variables. When Pinus needles were cut proximally to uniform length (50 mm), supercooling was unaffected by either weight or water content. Thus, ice nucleation temperature was an increasing function of the length of needles, or, more precisely, of the length of the stele, or, still more precisely, of the number of water-conducting capillary units contributing to that length, but ultimately of the number and quality of favorable nucleation sites contained therein. It is suggested that nucleation takes place at sites associated with the cell walls and not on nucleators suspended in the water.

scholarly journals Freezing nucleation apparatus puts new slant on study of biological ice nucleators in precipitation

2014 ◽  
Vol 7 (1) ◽  
pp. 129-134 ◽  
Author(s):  
E. Stopelli ◽  
F. Conen ◽  
L. Zimmermann ◽  
C. Alewell ◽  
C. E. Morris
Keyword(s):  
Light Transmission ◽  
Freezing Temperature ◽  
Partial Solution ◽  
Ice Nucleation ◽  
Precipitation Sample ◽  
Ice Nucleators ◽  
New Apparatus ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
Scatter Light

Abstract. For decades, drop-freezing instruments have contributed to a better understanding of biological ice nucleation and its likely implications for cloud and precipitation development. Yet, current instruments have limitations. Drops analysed on a cold stage are subject to evaporation and potential contamination. The use of closed tubes provides a partial solution to these problems, but freezing events are still difficult to be clearly detected. Here, we present a new apparatus where freezing in closed tubes is detected automatically by a change in light transmission upon ice development, caused by the formation of air bubbles and crystal facets that scatter light. Risks of contamination and introduction of biases linked to detecting the freezing temperature of a sample are then minimized. To illustrate the performance of the new apparatus we show initial results of two assays with snow samples. In one, we repeatedly analysed the sample (208 tubes) over the course of a month with storage at +4 °C, during which evidence for biological ice nucleation activity emerged through an increase in the number of ice nucleators active around −4 °C. In the second assay, we indicate the possibility of increasingly isolating a single ice nucleator from a precipitation sample, potentially determining the nature of a particle responsible for a nucleation activity measured directly in the sample. These two seminal approaches highlight the relevance of this handy apparatus for providing new points of view in biological ice nucleation research.

scholarly journals Ice nucleation efficiency of clay minerals in the immersion mode

2012 ◽  
Vol 12 (1) ◽  
pp. 3213-3261 ◽  
Author(s):  
V. Pinti ◽  
C. Marcolli ◽  
B. Zobrist ◽  
C. R. Hoyle ◽  
T. Peter
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Acid Treatment ◽  
Pure Water ◽  
Source Region ◽  
Freezing Temperature ◽  
Nucleation Site ◽  
Ice Nucleation ◽  
Nucleation Sites ◽  
Mineral Society

Abstract. Emulsion and bulk freezing experiments were performed to investigate immersion ice nucleation on clay minerals in pure water, using various kaolinites, montmorillonites, illites as well as natural dust from the Hoggar Mountains in the Saharan region. DSC (differential scanning calorimeter) measurements were performed on the kaolinites KGa-1b and KGa-2 from the Clay Mineral Society and kaolinite from Sigma-Aldrich; the montmorillonites SWy-2 and STx-1b from the Clay Mineral Society and the acid treated montmorillonites KSF and K-10 from Sigma Aldrich; the illites NX and SE from Arginotec. The emulsion experiments provide information on the average freezing behaviour characterized by the average nucleation sites. These experiments revealed one to two distinct heterogeneous freezing peaks, which suggest the presence of a low number of qualitatively distinct average nucleation site classes. We refer to the peak at the lowest temperature as "standard peak" and to the one at higher temperatures as "special peak". Conversely, freezing in bulk samples is not initiated by the average nucleation sites, but by a very low number of "best sites". The kaolinites showed quite narrow standard peaks with onset temperatures 239 K < Tonstd < 242 K and best sites with averaged median freezing temperature Tmedbest = 257 K. Only the kaolinite from Sigma Aldrich featured a special peak with freezing onset at 248 K. The illites showed broad standard peaks with freezing onsets at 244 K < Tonstd < 246 K and best sites with averaged median freezing temperature Tmedbest = 262 K. Montmorillonites had standard peaks with onsets 238 K < Tonstd < 240 K and best sites with Tmedbest=257 K. SWy-2, M K10, and KSF featured special peaks with onsets at Tonspcl=247, 240, and 242 K, respectively. M K10 and KSF both from Sigma Aldrich had less intense standard peaks compared to the ones from the Clay Mineral Society suggesting that a fraction of the standard sites are lost by the acid treatment. The acid treatment had however, no evident effect on best sites. Our investigations demonstrate that immersion freezing temperatures of clay minerals strongly depend on the amount of clay mineral present per droplet and on the exact type (location of collection and pre-treatment) of the clay mineral. We suggest that apparently contradictory results obtained by different groups with different setups can indeed be brought into good agreement when only clay minerals of the same type and amount per droplet are compared. The natural sample from the Hoggar Mountains, a region whose dusts have been shown to be composed mainly of illite, showed very similar freezing characteristics to the illites with freezing peak onsets 247 K < Tonstd < 248 K for the average and Tmedbest = 261 K for the best sites. Relating the concentration of best IN to the dust concentration in the atmosphere suggested that the best IN in the Hoggar sample would be common enough downwind of their source region to account for ambient IN number densities in the temperature range of 250–260 K at least during dust events.

scholarly journals Generalisation of Levine's prediction for the distribution of freezing temperatures of droplets: a general singular model for ice nucleation

2013 ◽  
Vol 13 (14) ◽  
pp. 7215-7223 ◽  
Author(s):  
R. P. Sear
Keyword(s):  
Extreme Value Distribution ◽  
Freezing Temperature ◽  
Nucleation Site ◽  
Ice Nucleation ◽  
Extreme Value ◽  
Extreme Value Statistics ◽  
Maximum Value ◽  
Nucleation Sites ◽  
Explicit Time Dependence ◽  
Freezing Temperatures

Abstract. Models without an explicit time dependence, called singular models, are widely used for fitting the distribution of temperatures at which water droplets freeze. In 1950 Levine developed the original singular model. His key assumption was that each droplet contained many nucleation sites, and that freezing occurred due to the nucleation site with the highest freezing temperature. The fact that freezing occurs due to the maximum value out of a large number of nucleation temperatures, means that we can apply the results of what is called extreme-value statistics. This is the statistics of the extreme, i.e. maximum or minimum, value of a large number of random variables. Here we use the results of extreme-value statistics to show that we can generalise Levine's model to produce the most general singular model possible. We show that when a singular model is a good approximation, the distribution of freezing temperatures should always be given by what is called the generalised extreme-value distribution. In addition, we also show that the distribution of freezing temperatures for droplets of one size, can be used to make predictions for the scaling of the median nucleation temperature with droplet size, and vice versa.

scholarly journals Generalisation of Levine's prediction for the distribution of freezing temperatures of droplets: a general singular model for ice nucleation

2013 ◽  
Vol 13 (4) ◽  
pp. 10499-10520 ◽  
Author(s):  
R. P. Sear
Keyword(s):  
Extreme Value Distribution ◽  
Freezing Temperature ◽  
Nucleation Site ◽  
Ice Nucleation ◽  
Extreme Value ◽  
Extreme Value Statistics ◽  
Maximum Value ◽  
Nucleation Sites ◽  
Explicit Time Dependence ◽  
Freezing Temperatures

Abstract. Models without an explicit time dependence, called singular models, are widely used for fitting the distribution of temperatures at which water droplets freeze. In 1950 Levine developed the original singular model. His key assumption was that each droplet contained many nucleation sites, and that freezing occurred due to the nucleation site with the highest freezing temperature. The fact that freezing occurs due to the maximum value out of large number of nucleation temperatures, means that we can apply the results of what is called extreme-value statistics. This is the statistics of the extreme, i.e., maximum or minimum, value of a large number of random variables. Here we use the results of extreme-value statistics to show that we can generalise Levine's model to produce the most general singular model possible. We show that when a singular model is a good approximation, the distribution of freezing temperatures should always be given by what is called the generalised extreme-value distribution. In addition, we also show that the distribution of freezing temperatures for droplets of one size, can be used to make predictions for the scaling of the median nucleation temperature with droplet size, and vice versa.

scholarly journals Freezing nucleation apparatus puts new slant on study of biological ice nucleators in precipitation

2013 ◽  
Vol 6 (5) ◽  
pp. 9163-9180 ◽  
Author(s):  
E. Stopelli ◽  
F. Conen ◽  
L. Zimmermann ◽  
C. Alewell ◽  
C. E. Morris
Keyword(s):  
Light Transmission ◽  
Freezing Temperature ◽  
Partial Solution ◽  
Ice Nucleation ◽  
Precipitation Sample ◽  
Ice Nucleators ◽  
New Apparatus ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
Scatter Light

Abstract. Since decades, drop-freezing instruments have contributed to a better understanding of biological ice nucleation and its likely implications on cloud and precipitation development. Yet, current instruments have limitations. Drops analysed on a cold stage are subject to evaporation and potential contamination. The use of closed tubes provides a partial solution to these problems, but freezing events are still difficult to be clearly detected. Here, we present a new apparatus where freezing in closed tubes is detected automatically by a change in light transmission upon ice development, caused by the formation of air bubbles and crystal facets that scatter light. Risks of contamination and introduction of biases linked to detecting the freezing temperature of a sample are then minimized. To illustrate the performance of the new apparatus we show initial results of two assays with snow samples. In one, we repeatedly analysed the sample (208 tubes) over the course of a month with storage at +4 °C, during which evidence for biological ice nucleation activity emerged through an increase in the number of ice nucleators active around −4 °C. In the second assay, we indicate the possibility to increasingly isolate a single ice nucleator from a precipitation sample, potentially determining the nature of a particle responsible for a nucleation activity measured directly in the sample. These two seminal approaches highlight the relevance of this handy apparatus to provide new points of view in biological ice nucleation research.

scholarly journals Condensed-phase biogenic–anthropogenic interactions with implications for cold cloud formation

2017 ◽  
Vol 200 ◽  
pp. 165-194 ◽  
Author(s):  
Joseph C. Charnawskas ◽  
Peter A. Alpert ◽  
Andrew T. Lambe ◽  
Thomas Berkemeier ◽  
Rachel E. O’Brien ◽  
...  
Keyword(s):  
Freezing Temperature ◽  
Organic Aerosol ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Cloud Formation ◽  
Fossil Fuel Combustion ◽  
Soot Particles ◽  
Ice Nuclei ◽  
Deliquescence Relative Humidity ◽  
Homogeneous Freezing

Anthropogenic and biogenic gas emissions contribute to the formation of secondary organic aerosol (SOA). When present, soot particles from fossil fuel combustion can acquire a coating of SOA. We investigate SOA–soot biogenic–anthropogenic interactions and their impact on ice nucleation in relation to the particles’ organic phase state. SOA particles were generated from the OH oxidation of naphthalene, α-pinene, longifolene, or isoprene, with or without the presence of sulfate or soot particles. Corresponding particle glass transition (Tg) and full deliquescence relative humidity (FDRH) were estimated using a numerical diffusion model. Longifolene SOA particles are solid-like and all biogenic SOA sulfate mixtures exhibit a core–shell configuration (i.e.a sulfate-rich core coated with SOA). Biogenic SOA with or without sulfate formed ice at conditions expected for homogeneous ice nucleation, in agreement with respectiveTgand FDRH. α-pinene SOA coated soot particles nucleated ice above the homogeneous freezing temperature with soot acting as ice nuclei (IN). At lower temperatures the α-pinene SOA coating can be semisolid, inducing ice nucleation. Naphthalene SOA coated soot particles acted as ice nuclei above and below the homogeneous freezing limit, which can be explained by the presence of a highly viscous SOA phase. Our results suggest that biogenic SOA does not play a significant role in mixed-phase cloud formation and the presence of sulfate renders this even less likely. However, anthropogenic SOA may have an enhancing effect on cloud glaciation under mixed-phase and cirrus cloud conditions compared to biogenic SOA that dominate during pre-industrial times or in pristine areas.

scholarly journals Ice nucleation activity identified in some phytopathogenic Fusarium species

2005 ◽  
Vol 77 (2) ◽  
pp. 83-92 ◽  
Author(s):  
C. Richard ◽  
J.-G. Martin ◽  
S. Pouleur
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Species ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Free Living ◽  
Factors Affecting ◽  
Pure Cultures ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
Positive Controls

In order to know which species of Fusarium are ice nucleating and to determine the factors affecting their pathogenicity, ice nucleation activity (INA) was examined in Fusarium oxysporum, F. sporotrichioides, and F. tricinctum. Positive controls (lna+) used were F. acuminatum and F. avenaceum. The test for fungal INA was done with a simple and rapid tube nucleation assay. Twelve out of the 42 F. oxysporum isolates, and 8 out of 14 F. tricinctum isolates were lna+. No INA was detected in F sporotrichioides. In this test the threshold freezing temperature tended to increase with culture age, reaching a peak of -1°C in a few samples, which is as high as the warmest INA reported for bacteria, and higher than the INA detected in pure cultures of free-living fungi, lichen fungi, lichen algae and cyanobacteria. This is the first report of INA for F oxysporum.

scholarly journals Ice nucleation efficiency of AgI: review and new insights

2016 ◽  
Author(s):  
Claudia Marcolli ◽  
Baban Nagare ◽  
André Welti ◽  
Ulrike Lohmann
Keyword(s):  
Water Saturation ◽  
Experimental Studies ◽  
Freezing Temperature ◽  
Nucleating Agent ◽  
Companion Paper ◽  
Chem Phys ◽  
Ice Nucleation ◽  
Lattice Match ◽  
Ice Nuclei ◽  
Immersion Freezing

Abstract. AgI is one of the best investigated ice nuclei. It has relevance for the atmosphere since it is used for glaciogenic cloud seeding. Theoretical and experimental studies over the last sixty years provide a complex picture of silver iodide as ice nucleating agent with conflicting and inconsistent results. This review compares experimental ice nucleation studies in order to analyse the factors that influence the ice nucleation ability of AgI. We have performed experiments to compare contact and immersion freezing by AgI. This is one of three papers that describe and analyse contact and immersion freezing experiments with AgI. In Nagare et al. (Nagare, B., Marcolli, C., Stetzer, O., and Lohmann, U.: Comparison of measured and calculated collision efficiencies at low temperatures, Atmos. Chem. Phys., 15, 13759–13776, doi:10.5194/acp-15-13759-2015, 2015) collision efficiencies based on contact freezing experiments with AgI are determined and compared with theoretical formulations. In a companion paper, contact freezing experiments are compared with immersion freezing experiments conducted with AgI, kaolinite, and ATD as ice nuclei. The following picture emerges from this analysis: The ice nucleation ability of AgI seems to be enhanced when the AgI particle is on the surface of a droplet, which is indeed the position that a particle takes when it can freely move in a droplet. Ice nucleation by particles with surfaces exposed to air, depends on water adsorption. AgI surfaces seem to be most efficient as ice nuclei when they are exposed to relative humidity at or even above water saturation. For AgI particles that are totally immersed in water, the freezing temperature increases with increasing AgI surface area. Higher threshold freezing temperature seem to correlate with improved lattice matches as can be seen for AgI-AgCl solid solutions and 3AgI•NH4I•6H2O, which have slightly better lattice matches with ice than AgI and also higher threshold freezing temperatures. However, the effect of a good lattice match is annihilated when the surfaces have charges. Also, the ice nucleation ability seems to decrease during dissolution of AgI particles. This introduces an additional history and time dependence of ice nucleation in cloud chambers with short residence times.

scholarly journals An instrument for quantifying heterogeneous ice nucleation in multiwell plates using infrared emissions to detect freezing

2018 ◽  
Vol 11 (10) ◽  
pp. 5629-5641 ◽  
Author(s):  
Alexander D. Harrison ◽  
Thomas F. Whale ◽  
Rupert Rutledge ◽  
Stephen Lamb ◽  
Mark D. Tarn ◽  
...  
Keyword(s):  
Active Sites ◽  
Freezing Temperature ◽  
Equilibrium Temperature ◽  
Ice Nucleation ◽  
Ir Camera ◽  
Low Concentrations ◽  
Immersion Freezing ◽  
Mixed Phase Clouds ◽  
The City ◽  
Good Agreement

Abstract. Low concentrations of ice-nucleating particles (INPs) are thought to be important for the properties of mixed-phase clouds, but their detection is challenging. Hence, there is a need for instruments where INP concentrations of less than 0.01 L−1 can be routinely and efficiently determined. The use of larger volumes of suspension in drop assays increases the sensitivity of an experiment to rarer INPs or rarer active sites due to the increase in aerosol or surface area of particulates per droplet. Here we describe and characterise the InfraRed-Nucleation by Immersed Particles Instrument (IR-NIPI), a new immersion freezing assay that makes use of IR emissions to determine the freezing temperature of individual 50 µL droplets each contained in a well of a 96-well plate. Using an IR camera allows the temperature of individual aliquots to be monitored. Freezing temperatures are determined by detecting the sharp rise in well temperature associated with the release of heat caused by freezing. In this paper we first present the calibration of the IR temperature measurement, which makes use of the fact that following ice nucleation aliquots of water warm to the ice–liquid equilibrium temperature (i.e. 0 ∘C when water activity is ∼1), which provides a point of calibration for each individual well in each experiment. We then tested the temperature calibration using ∼100 µm chips of K-feldspar, by immersing these chips in 1 µL droplets on an established cold stage (µL-NIPI) as well as in 50 µL droplets on IR-NIPI; the results were consistent with one another, indicating no bias in the reported freezing temperature. In addition we present measurements of the efficiency of the mineral dust NX-illite and a sample of atmospheric aerosol collected on a filter in the city of Leeds. NX-illite results are consistent with literature data, and the atmospheric INP concentrations were in good agreement with the results from the µL-NIPI instrument. This demonstrates the utility of this approach, which offers a relatively high throughput of sample analysis and access to low INP concentrations.

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