scholarly journals Modeling interfacial liquid layers on environmental ices

2011 ◽  
Vol 11 (18) ◽  
pp. 9971-9982 ◽  
Author(s):  
M. H. Kuo ◽  
S. G. Moussa ◽  
V. F. McNeill
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Low Temperatures ◽  
Freezing Point ◽  
Triple Junctions ◽  
Ice Crystal ◽  
Freezing Point Depression ◽  
Chemical Interactions ◽  
Interfacial Layers ◽  
Wide Range

Abstract. Interfacial layers on ice significantly influence air-ice chemical interactions. In solute-containing aqueous systems, a liquid brine may form upon freezing due to the exclusion of impurities from the ice crystal lattice coupled with freezing point depression in the concentrated brine. The brine may be segregated to the air-ice interface where it creates a surface layer, in micropockets, or at grain boundaries or triple junctions. We present a model for brines and their associated liquid layers in environmental ice systems that is valid over a wide range of temperatures and solute concentrations. The model is derived from fundamental equlibrium thermodynamics and takes into account nonideal solution behavior in the brine, partitioning of the solute into the ice matrix, and equilibration between the brine and the gas phase for volatile solutes. We find that these phenomena are important to consider when modeling brines in environmental ices, especially at low temperatures. We demonstrate its application for environmentally important volatile and nonvolatile solutes including NaCl, HCl, and HNO3. The model is compared to existing models and experimental data from literature where available. We also identify environmentally relevant regimes where brine is not predicted to exist, but the QLL may significantly impact air-ice chemical interactions. This model can be used to improve the representation of air-ice chemical interactions in polar atmospheric chemistry models.

scholarly journals Liquid-like layers on ice in the environment: bridging the quasi-liquid and brine layer paradigms

2011 ◽  
Vol 11 (3) ◽  
pp. 8145-8172 ◽  
Author(s):  
M. H. Kuo ◽  
S. G. Moussa ◽  
V. F. McNeill
Keyword(s):  
Atmospheric Chemistry ◽  
Freezing Point ◽  
Unified Model ◽  
Polar Regions ◽  
Ice Crystal ◽  
Wide Range ◽  
Surface Disorder ◽  
Quasi Liquid Layer ◽  
Statistical Mechanical ◽  
Brine Layer

Abstract. Liquid-like layers on ice significantly influence atmospheric chemistry in polar regions. In the absence of impurities a nanoscale region of surface disorder known as the "quasi-liquid layer" (QLL) may exist below the bulk melting point (down to ~−30 °C). Surface and bulk impurities are known to modulate the QLL thickness. In aqueous systems containing ionic solutes, a liquid brine layer (BL) may form upon freezing due to the exclusion of impurities from the ice crystal lattice coupled with freezing point depression in the concentrated surface layer. Brine layers are conceptually distinct from the QLL, which can exist in the absence of impurities. We have developed a unified model for liquid-like layers in environmental ice systems that is valid over a wide range of temperatures and solute concentrations, spanning the QLL and BL regimes. The model consists of two coupled modules describing the thickness of the BL and the QLL. The BL module is derived from fundamental equlibrium thermodynamics, whereas the QLL formulation is derived semi-empirically based on statistical mechanical principles and previously published QLL thickness data. The resulting unified model has been tested against experimental data from literature and applied to several environmentally important systems, such as HCl(g)-ice, HNO3(g)-ice, and frozen sea ice. This model can be used to improve the representation of air-ice chemical interactions in polar atmospheric chemistry models.

scholarly journals Growth suppression of ice crystal basal face in the presence of a moderate ice-binding protein does not confer hyperactivity

2018 ◽  
Vol 115 (29) ◽  
pp. 7479-7484 ◽  
Author(s):  
Maddalena Bayer-Giraldi ◽  
Gen Sazaki ◽  
Ken Nagashima ◽  
Sepp Kipfstuhl ◽  
Dmitry A. Vorontsov ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Heat Dissipation ◽  
Freezing Point ◽  
Binding Protein ◽  
Ice Crystals ◽  
Ice Crystal ◽  
Freezing Point Depression ◽  
Basal Face ◽  
Ice Binding ◽  
Ice Binding Protein

Ice-binding proteins (IBPs) affect ice crystal growth by attaching to crystal faces. We present the effects on the growth of an ice single crystal caused by an ice-binding protein from the sea ice microalga Fragilariopsis cylindrus (fcIBP) that is characterized by the widespread domain of unknown function 3494 (DUF3494) and known to cause a moderate freezing point depression (below 1 °C). By the application of interferometry, bright-field microscopy, and fluorescence microscopy, we observed that the fcIBP attaches to the basal faces of ice crystals, thereby inhibiting their growth in the c direction and resulting in an increase in the effective supercooling with increasing fcIBP concentration. In addition, we observed that the fcIBP attaches to prism faces and inhibits their growth. In the event that the effective supercooling is small and crystals are faceted, this process causes an emergence of prism faces and suppresses crystal growth in the a direction. When the effective supercooling is large and ice crystals have developed into a dendritic shape, the suppression of prism face growth results in thinner dendrite branches, and growth in the a direction is accelerated due to enhanced latent heat dissipation. Our observations clearly indicate that the fcIBP occupies a separate position in the classification of IBPs due to the fact that it suppresses the growth of basal faces, despite its moderate freezing point depression.

scholarly journals Atmospheric chemistry and physics in the atmosphere of a developed megacity (London): an overview of the REPARTEE experiment and its conclusions

2012 ◽  
Vol 12 (6) ◽  
pp. 3065-3114 ◽  
Author(s):  
R. M. Harrison ◽  
M. Dall'Osto ◽  
D. C. S. Beddows ◽  
A. J. Thorpe ◽  
W. J. Bloss ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Urban Atmosphere ◽  
Trace Gas ◽  
Chemical Components ◽  
Chemical Transformations ◽  
Specific Chemical ◽  
Gas Dispersion ◽  
Wide Range

Abstract. The REgents PARk and Tower Environmental Experiment (REPARTEE) comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160–190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a) demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b) generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c) quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d) generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e) provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f) the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g) studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h) new information on the chemical composition and source apportionment of particulate matter size fractions in the atmosphere of London derived both from bulk chemical analysis and aerosol mass spectrometry with two instrument types.

Osmoregulation in Trichocorixa verticalis interiores Sailer (Hemiptera, Corixidae) — an inhabitant of Saskatchewan saline lakes, Canada

1975 ◽  
Vol 53 (9) ◽  
pp. 1207-1212 ◽  
Author(s):  
Patricia I. Tones ◽  
U. T. Hammer
Keyword(s):  
Saline Lakes ◽  
Freezing Point ◽  
Saline Water ◽  
Adult Population ◽  
Ionic Composition ◽  
Tolerance Limit ◽  
Freezing Point Depression ◽  
Wide Range ◽  
The Mean

Results of freezing point depression determinations of haemolymph show that first instars, third instars, and adults of Trichocorixa verticalis interiores have well-developed powers of osmoregulation and can hyporegulate in saline water. This species can osmoregulate equally well at 13, 20, and 25 °C but the mean tolerance limit decreases as the temperature increases. T. verticalis interiores is also tolerant to changes in ionic composition. The osmoregulation of this species is similar to that of Sigara stagnalis rather than most Corixidae which are unable to hyporegulate. T. verticalis interiores was collected quantitatively from six athalassic saline lakes which were selected to represent a wide range of salinities. The maximum adult population and conductivity and ionic composition of the water are reported for each lake.

scholarly journals In vitro uses of biological cryoprotectants

2002 ◽  
Vol 357 (1423) ◽  
pp. 945-951 ◽  
Author(s):  
Peter J. Lillford ◽  
Chris B. Holt
Keyword(s):  
Crystal Growth ◽  
Freezing Point ◽  
Ice Nucleation ◽  
Active Species ◽  
Osmotic Regulation ◽  
Ice Crystal ◽  
Freezing Point Depression ◽  
Commercial Use ◽  
Crystal Growth Inhibition

Ice can be anything from a highly destructive agent in agriculture to a useful building material. Established industries are based on the known rules of physics and chemistry which allow some control of amounts of ice or ice crystal geometry. However, organisms have much more subtle requirements to maintain their delicate internal structure if they are to survive freezing. As a result they have selected specific molecules for freezing–point depression, osmotic regulation, ice nucleation and crystal growth inhibition. All these active species may have potential commercial use once they are identified, understood and produced at economic scales. We examine the progress made so far in extending biological subtlety into commercial processes, and look for prospects for further innovation.

scholarly journals Discovery of Hyperactive Antifreeze Protein from Phylogenetically Distant Beetles Questions Its Evolutionary Origin

2021 ◽  
Vol 22 (7) ◽  
pp. 3637
Author(s):  
Tatsuya Arai ◽  
Akari Yamauchi ◽  
Ai Miura ◽  
Hidemasa Kondo ◽  
Yoshiyuki Nishimiya ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Tandem Repeats ◽  
Freezing Point ◽  
Consensus Sequence ◽  
Antifreeze Protein ◽  
Ice Crystal ◽  
Freezing Point Depression ◽  
Entire Surface ◽  
Chilled Storage ◽  
Peptide Region

Beetle hyperactive antifreeze protein (AFP) has a unique ability to maintain a supercooling state of its body fluids, however, less is known about its origination. Here, we found that a popular stag beetle Dorcus hopei binodulosus (Dhb) synthesizes at least 6 isoforms of hyperactive AFP (DhbAFP). Cold-acclimated Dhb larvae tolerated −5 °C chilled storage for 24 h and fully recovered after warming, suggesting that DhbAFP facilitates overwintering of this beetle. A DhbAFP isoform (~10 kDa) appeared to consist of 6−8 tandem repeats of a 12-residue consensus sequence (TCTxSxNCxxAx), which exhibited 3 °C of high freezing point depression and the ability of binding to an entire surface of a single ice crystal. Significantly, these properties as well as DNA sequences including the untranslated region, signal peptide region, and an AFP-encoding region of Dhb are highly similar to those identified for a known hyperactive AFP (TmAFP) from the beetle Tenebrio molitor (Tm). Progenitor of Dhb and Tm was branched off approximately 300 million years ago, so no known evolution mechanism hardly explains the retainment of the DNA sequence for such a lo­ng divergence period. Existence of unrevealed gene transfer mechanism will be hypothesized between these two phylogenetically distant beetles to acquire this type of hyperactive AFP.

scholarly journals Atmospheric chemistry and physics in the atmosphere of a developed megacity (London): an overview of the REPARTEE experiment and its conclusions

2011 ◽  
Vol 11 (11) ◽  
pp. 30145-30271 ◽  
Author(s):  
R. M. Harrison ◽  
M. Dall'Osto ◽  
D. C. S. Beddows ◽  
A. J. Thorpe ◽  
W. J. Bloss ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Urban Atmosphere ◽  
Trace Gas ◽  
Chemical Components ◽  
Chemical Transformations ◽  
Specific Chemical ◽  
Gas Dispersion ◽  
Wide Range

Abstract. The Regents Park and Tower Environmental Experiment (REPARTEE) comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160–190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a) demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b) generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c) quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d) generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e) provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f) the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g) studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h) new information on the chemical composition and source apportionment of particulate matter size fractions in the atmosphere of London derived both from bulk chemical analysis and aerosol mass spectrometry with two instrument types.

Intrinsic Stacking Interactions of Natural and Artificial Nucleobases

2019 ◽  
Author(s):  
Drew P. Harding ◽  
Laura J. Kingsley ◽  
Glen Spraggon ◽  
Steven Wheeler
Keyword(s):  
Gas Phase ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Molecular Descriptors ◽  
Stacking Interactions ◽  
Interaction Energies ◽  
Functional Theory ◽  
Binding Partner ◽  
Heavy Atoms ◽  
Wide Range

The intrinsic (gas-phase) stacking energies of natural and artificial nucleobases were explored using density functional theory (DFT) and correlated ab initio methods. Ranking the stacking strength of natural nucleobase dimers revealed a preference in binding partner similar to that seen from experiments, namely G > C > A > T > U. Decomposition of these interaction energies using symmetry-adapted perturbation theory (SAPT) showed that these dispersion dominated interactions are modulated by electrostatics. Artificial nucleobases showed a similar stacking preference for natural nucleobases and were also modulated by electrostatic interactions. A robust predictive multivariate model was developed that quantitively predicts the maximum stacking interaction between natural and a wide range of artificial nucleobases using molecular descriptors based on computed electrostatic potentials (ESPs) and the number of heavy atoms. This model should find utility in designing artificial nucleobase analogs that exhibit stacking interactions comparable to those of natural nucleobases. Further analysis of the descriptors in this model unveil the origin of superior stacking abilities of certain nucleobases, including cytosine and guanine.

Sign in / Sign up

Export Citation Format

Share Document