Why is Ice Slippery? Simulations of Shear Viscosity of the Quasi-Liquid Layer on Ice

Louden, Patrick B.; Gezelter, J. Daniel

doi:10.1021/acs.jpclett.8b01339

Cited by 21 publications

(31 citation statements)

References 37 publications

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“…The water molecules in this layer is mobile 9 and its viscosity has been reported to be comparable to that of bulk water. 10 This disordered layer is typically captured by using MD simulations and molecular-scale measurements such as sum-frequency generation (SFG) spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

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The Surface of Ice under Equilibrium and Nonequilibrium Conditions

et al. 2019

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Conspectus The ice premelt, often called the quasi-liquid layer (QLL), is key for the lubrication of ice, gas uptake by ice, and growth of aerosols. Despite its apparent importance, in-depth understanding of the ice premelt from the microscopic to the macroscopic scale has not been gained. By reviewing data obtained using molecular dynamics (MD) simulations, sum-frequency generation (SFG) spectroscopy, and laser confocal differential interference contrast microscopy (LCM-DIM), we provide a unified view of the experimentally observed variation in quasi-liquid (QL) states. In particular, we disentangle three distinct types of QL states of disordered layers, QL-droplet, and QL-film and discuss their nature. The topmost ice layer is energetically unstable, as the topmost interfacial H 2 O molecules lose a hydrogen bonding partner, generating a disordered layer at the ice–air interface. This disordered layer is homogeneously distributed over the ice surface. The nature of the disordered layer changes over a wide temperature range from −90 °C to the bulk melting point. Combined MD simulations and SFG measurements reveal that the topmost ice surface starts to be disordered around −90 °C through a process that the topmost water molecules with three hydrogen bonds convert to a doubly hydrogen-bonded species. When the temperature is further increased, the second layer starts to become disordered at around −16 °C. This disordering occurs not in a gradual manner, but in a bilayer-by-bilayer manner. When the temperature reaches −2 °C, more complicated structures, QL-droplet and QL-film, emerge on the top of the ice surface. These QL-droplets and QL-films are inhomogeneously distributed, in contrast to the disordered layer. We show that these QL-droplet and QL-film emerge only under supersaturated/undersaturated vapor pressure conditions, as partial and pseudopartial wetting states, respectively. Experiments with precisely controlled pressure show that, near the water vapor pressure at the vapor-ice equilibrium condition, no QL-droplet and QL-film can be observed, implying that the QL-droplet and QL-film emerge exclusively under nonequilibrium conditions, as opposed to the disordered layers formed under equilibrium conditions. These findings are connected with many phenomena related to the ice surface. For example, we explain how the disordering of the topmost ice surface governs the slipperiness of the ice surface, allowing for ice skating. Further focus is on the gas uptake mechanism on the ice surface. Finally, we note the unresolved questions and future challenges regarding the ice premelt.

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Section: Introductionmentioning

confidence: 99%

“…9 These strongly suggest that the dynamics of the topmost interfacial water molecules play a central role in reducing the friction of ice surfaces. 9,10…”

Section: Introductionmentioning

confidence: 99%

The Surface of Ice under Equilibrium and Nonequilibrium Conditions

et al. 2019

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“…The ice-QLL provides diverse physicochemical properties (e.g., rigidity of the crystalline structure, water diffusivity, viscosity, etc.) as a function of depth and temperature 42,[46][47][48] that are not obtainable in liquid water.…”

Section: Discussionmentioning

confidence: 99%

Solvation and Stabilization of Single-Strand RNA at the Air/Ice Interface Support a Primordial RNA World on Ice

et al. 2020

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Outstanding questions about the RNA world hypothesis for the emergence of life on Earth concern the stability and self-replication of prebiotic aqueous RNA. Recent experimental work has suggested that solid substrates and low temperatures could help resolve these issues. Here, we use classical molecular dynamics simulations to explore the possibility that the substrate is ice itself. We find that at -20 C, a quasi-liquid layer at the air/ice interface solvates a short (8nucleotide) RNA strand such that phosphate groups tend to anchor to specific points of the underlying crystal lattice, lengthening the strand. Hydrophobic bases, meanwhile, tend to migrate to the air/ice interface. Further, contacts between solvent water and ribose 2-OH' groups are found to occur less frequently for RNA on ice than for aqueous RNA at the same temperature; this reduces the likelihood of deprotonation of the 2-OH' and its subsequent nucleophilic attack on the phosphate diester. The implied enhanced resistance to hydrolysis, in turn, could increase opportunities for polymerization and self-copying. These findings thus offer the possibility of a role for an ancient RNA world on ice distinct from that considered in extant elaborations of the RNA world hypothesis. This work is, to the best of our knowledge, the first molecular dynamics study of RNA on ice.

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“…Moreover, in a water restricted environment such as the topmost layers of the air/ice interface, the bases would be more prone to base-stacking, enabling the correct base pairing with other free nucleotide that would be floating in the topmost part of the ice-QLL, where the water diffusivity is faster. 42 In addition, since the synthesis of building blocks for nucleotide synthesis has been shown to be plausible in prebiotic aqueous conditions, 14,[43][44] an immobilized and stretched out ssRNA on ice, as the one shown in Fig. 1b, could be more prone to polymerization and self-replication with free nucleotides diffusing in the ice-QLL than a compact arrangement in the absence of protein-assisted replicase.…”

Section: Discussionmentioning

confidence: 99%

Solvation and Stabilization of Single Strand RNA at the Air/ice Interface Support a Primordial RNA World on Ice

Gladich¹,

Berrens²,

Rowe³

et al. 2020

Preprint

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<div>Outstanding questions about the RNA world hypothesis for the emergence of life</div><div>on Earth concern the stability and self-replication of prebiotic aqueous RNA.</div><div>Recent experimental work has suggested that solid substrates and low</div><div>temperatures could help resolve these issues. Here, we use classical molecular</div><div>dynamics simulations to explore the possibility that the substrate is ice itself. We</div><div>find that at -20 C, a quasi-liquid layer at the air/ice interface solvates a short (8-</div><div>nucleotide) RNA strand such that phosphate groups tend to anchor to specific</div><div>points of the underlying crystal lattice, lengthening the strand. Hydrophobic bases,</div><div>meanwhile, tend to migrate to the air/ice interface. Further, contacts between</div><div>solvent water and ribose 2-OH’ groups are found to occur less frequently for RNA</div><div>on ice than for aqueous RNA at the same temperature; this reduces the likelihood</div><div>of deprotonation of the 2-OH’ and its subsequent nucleophilic attack on the</div><div>phosphate diester. The implied enhanced resistance to hydrolysis, in turn, could</div><div>increase opportunities for polymerization and self-copying. These findings thus</div><div>offer the possibility of a role for an ancient RNA world on ice distinct from that</div><div>considered in extant elaborations of the RNA world hypothesis. This work is, to the</div><div>best of our knowledge, the first molecular dynamics study of RNA on ice</div>

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Why is Ice Slippery? Simulations of Shear Viscosity of the Quasi-Liquid Layer on Ice

Cited by 21 publications

References 37 publications

The Surface of Ice under Equilibrium and Nonequilibrium Conditions

The Surface of Ice under Equilibrium and Nonequilibrium Conditions

Solvation and Stabilization of Single-Strand RNA at the Air/Ice Interface Support a Primordial RNA World on Ice

Solvation and Stabilization of Single Strand RNA at the Air/ice Interface Support a Primordial RNA World on Ice

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