Ice Lattice Research Articles

A grand ensemble Monte Carlo investigation of the Bell lattice model for water

The lattice model for water, previously investigated by Bell using a Guggenheim-McGlashan first-order type of approximation (FOA), has been examined at three reduced temperatures T*=(kT/w)=0.2, 0.5 and 0.9 using grand ensemble Monte Carlo simulations. The parameters of the model are epsilon , w, u associated with first-neighbour energies, a hydrogen bond increment to this, and a 'penalty' incurred by molecules in triad sets on the two intertwined cubic ice lattices of the model. These parameters were given values suggested to be optimum by Bell ( epsilon /w=2.0, u/w=1.25). Results indicate that the cooperativity of the model is significantly underestimated by the FOA, although the general behaviour of the model is correctly represented. The authors have also made a preliminary examination of the possibility of introducing values of epsilon , w and u into the model which are directly related to H2O dimer potentials, rather than being estimated a posteriori from thermodynamic criteria. It is shown that this approach is feasible and that the advantage of extremely rapid calculation offered by the lattice model would not be lost.

Muonium in ice

Muonium has been studied in single crystals of H2O and D2O. Two-frequency precession in low transverse fields and a single zero-field oscillation indicate a small anisotropy of axial symmetry in the muonium hyperfine interaction. The anisotropy is shown to be the cause of the hitherto unexplained temperature independent contribution to muonium spin relaxation in polycrystalline samples. Relaxation rates for 99 K–263 K are reported for muonium in a single crystal of H2O. Relaxation is attributed to electron-nuclear dipolar coupling of muonium to lattice protons, modulated by translational diffusion of muonium alongc-axis channels of the ice lattice. A simple model for H and Mu diffusion in ice is investigated.

Gelation models of hydrogen bond networks in liquid water

Cluster statistics of hydrogen bond networks in water are calculated with the use of molecular dynamics (MD) and are compared with the predictions of gelation models. For small bond networks the MD calculations agree well with Flory theory (which neglects cycles), but they disagree for the larger networks. The MD data for the connectivity of the larger networks agree much better with our ice lattice calculations, providing the first MD test of the ability of Flory theory to describe polyfunctional condensation network statistics.

Solitons and proton motion in ice‐like structures

AbstractThe proton motion in hydrogen bonded quasi‐one‐dimensional molecular chains is investigated It is shown that elementary processes in one‐dimensional ice lattice are nonlinear autolocalized collective exitations which can spread over macroscopic distances retaining the energy, momentum, and charge. The results obtained can be used to explain some phenomena in biological systems.

Evidence for anisotropic diffusion of Mu in ice and implications for H

Muonium has been studied in single crystals of H 2O and D 2O. Orientation dependent precession frequencies reveal anisotropy in the hyperfine tensor of muonium. The axial symmetry suggests that Mu atoms diffuse preferentially along the c-axis channels of the ice lattice. H is expected to behave the same way.

Tests of effective pair potentials for water: Predicted ice structures

As a test of the accuracy of the several proposed effective pair potentials for water, we have examined how well they reproduce the structures and properties of the proton-ordered ices II, VIII, and IX, and those of a hypothetical proton ordered form of ice I which is closely related to ice Ih. Despite leading to a consistent underestimate of all the ice densities by roughly 21%, the ab initio pair potential calculated by Matsuoka, Clementi, and Yoshimine succeeds better than any other in predicting the hydrogen bonding topology and the O–O–O angles characteristic of the various ice lattices. Some of the proposed water–water potentials predict the existence of ice polymorphs entirely different from known forms of ice, and/or give rise to structures with bifurcated hydrogen bonds. Using our new results, and others in the literature, we give a detailed discussion of the features of the MCY, ST2, and RSL2 potentials, each considered a representative of a class of potentials.

Radiation processes in frozen aqueous systems

Primary events in the radiolysis of liquid and solid water are discussed. It is concluded that in low temperature solids, only H· and ·OH radicals need to be considered. Secondary processes involve reaction between H· and water to give ·OH and H 2, and the formation of H 2O 2 from ·OH radicals, but neither reaction occurs at ca. 4 K. Hence, mass-loss at low temperatures is probably not caused by chemical reactions, since both H· and ·OH are strongly bound into the ice lattice by hydrogen bonds. Possible reasons for blurring effects are considered, together with expectations for the effects of very high doses. Radiation effects in phase-separated aqueous systems, and in aqueous glasses are also discussed, a major new element for the latter being the formation of trapped-electron centres, and consequently also of trapped positive centres (H 3O +). Further chemical reactions in both inorganic and organic glasses are discussed.

Biological antifreeze agents in coldwater fishes

1. 1. Biological antifreezes are present in coldwater fishes and lower their freezing point below the freezing point of seawater (− 1.9°C), without substantially increasing the osmotic content of their body fluids. 2. 2. The antifreeze agents present in the Antarctic notothenioid and northern gadid fishes are glycopeptides composed of alanine, threonine, galactose and N-acetylgalactosamine. In other northern fishes they are peptides which differ substantially in composition between species, but are similar in that two thirds of their residues are alanine and they are rich in the polar residues aspartate, glutamate, threonine and serine. 3. 3. Although the average mol. wt of the antifreezes is between 5000 and 10,000. they have a very large effect, on the freezing point of water which has been termed an antifreeze effect. The depression of the freezing point occurs via the non-colligative mechanism, adsorption-inhibition. Adsorption to ice prevents water from joining the ice lattice by increasing the radius of curvature of the fronts on the growth steps of the crystals thereby increasing their surface free energy. 4. 4. The antifreezes are a permanent feature of the Antarctic fishes, but in many northern fishes they are present only during the winter and the antifreeze cycle appears to be an endogenous one. 5. 5. Antifreeze concentrations in the blood are between 3 and 4%, but they are not present in the urine. In the Antarctic and many northern species, the antifreezes are conserved in the circulation because the kidneys are aglomerular or functionally aglomerular. In the glomerular winter flounder, the acidic peptide antifreeze is conserved in the circulation because it is not filtered. Retention of the peptide occurs because it is repelled from the negatively charged basement membrane of the capillary wall. Small amounts of low mol. wt antifreeze are lost via the bile and digestive system where their role appears to be prevention of freezing of the dilute intestinal fluid.

Dynamical deductions from nuclear magnetic resonance relaxation measurements at the water-protein interface

Nuclear magnetic resonance (NMR) measurements provide both structural and dynamical information about the molecules in which nuclear resonances are observed. This manuscript addresses NMR relaxation of water protons in protein powder systems. Inclusion of magnetic communication between the water proton spins and protein proton spins leads to a clearer view of water molecule dynamics at the protein surface than has been previously available. We conclude that water molecule motion at the protein surface is somewhat slower than in the solute free solvent, but it is orders of magnitude faster than motions in a rigid ice lattice even in samples hydrated to levels well below what is generally thought to be the full hydration complement of the protein. The NMR relaxation data on lysozyme powders support a model that leaves adsorbed water very fluid at the protein surface with reorientational correlation times for the water shorter than nanoseconds.

Preparation of radiopharmaceuticals by Szilard-Chalmers labelling and radioprotection in an ice lattice

A new and simple method for the labelling of halogenated organic molecules and biomolecules is described. Dilute aqueous solutions of the halogenated molecule are irradiated with neutrons in the frozen state. The labelling yields are generally high for the 18 compounds investigated and constant over a large concentration range. The major observed labelled organic product is the radiohalogen labelled parent molecule with the halogen at its original site. Unlike neutron-irradiated liquid aqueous solutions of the same compounds no radiation damage to the molecules is observed for the irradiation times employed.

Quantum inverse method for two‐dimensional ice and ferroelectric lattice models

The quantum inverse scattering transform method previously developed for continuum field theories is applied to the exactly soluble symmetric six‐vertex (ice or ferroelectric) lattice model. Operators analogous to those which appear in the quantum inverse treatment of the nonlinear Schrödinger and sine–Gordon equations are constructed on the lattice by forming strings of vertices contracted over horizontal arrows. From the commutation relations for these operators, exact formulas for the eigenstates and eigenvalues of the transfer matrix are obtained without making an explicit ansatz for the wave functions. These results illustrate the connection between the quantum inverse method and the transfer matrix formalism for lattice models.

Information on the CO2 Cycle from Ice Core Studies

Information on the history of the atmospheric CO2 content and the 13C/12 and 14C/C ratios is recorded in natural ice. Measurements on samples from very cold accumulation regions show that CO2 is occluded not only in air bubbles, but also in the ice lattice. The two CO2 components are of similar size. It is very difficult to measure CO2 in the bubbles and CO2 in the ice lattice separately. By melting the samples and extracting the evolving gases in two fractions, it is possible to estimate CO2 concentration in the bubbles and the ice lattice. Enrichment or depletion of CO2 in the bubbles by exchange with the ice is difficult to estimate. Information about this effect is expected from 13C/12C analysis on the extracted CO2 fractions.To investigate whether atmospheric CO2 content was different during the last glaciation than during the present one, sets of 16 and 20 samples distributed over the last 40,000 years from the two deep ice cores from Camp Century (North Greenland) and Byrd Station (West Antarctica) were measured. The time scales for the two cores are based on a rheological model. Results and conclusions are: —The data series from both cores show similar trends correlated to a certain degree to the δ18O profiles.—For both cores, the values for the CO2 concentration of the first fraction, considered to best represent the atmospheric composition, show lower values during glaciation than in the Holocene, with a minimum before the end of glaciation.—Low CO2 concentrations in the first fractions (200ppm) of certain samples are a strong indication that the atmospheric CO2 concentration during last glaciation was lower than during the postglacial. These low concentrations indicate that, at that time, CO2 concentration in the atmosphere could have been lower than today by a factor of 1.5. Possible explanations for such a change in atmospheric CO2 content as well as its influence on atmospheric 14C/C ratio and on the radiation balance is discussed.

Polarization processes in the ice lattice

Polarization processes in the ice lattice

Polarization processes in the ice lattice

Polarization processes in the ice lattice

Laplace pressure inside micelles

The results of studies of the caging of ice on the germinate recombination of (n-..gamma..)-activated /sup 128/I in dilute aqueous mixtures of monoiodotyrosine and diiodotyrosine are reported. The products were identified by high performance liquid chromotography. Three reaction routes leading to /sup 128/I-labeled organic products are proposed. The results suggest that the /sup 128/I formed remains quite close to its organic radical due to efficient caging ability of the ice lattice.

Caging effects of an ice lattice on high-energy iodine geminate recombination with biomolecules

Caging effects of an ice lattice on high-energy iodine geminate recombination with biomolecules

Dielectric Behaviour of Ice Microcrystals: A Study Versus Temperature

AbstractDispersions of ice microcrystals were obtained from the breakdown of supercooling of water-in-oil type emulsions whose disperse phase was either resin-exchanged water or aqueous solutions of NH4Cl. Their complex permittivity ε⋆ = ε´–jε˝ was studied versus temperature T, up to the melting point of ice microcrystals, by means of an automatically balancing admittance bridge (General Radio 1680 A) working at 400 Hz and 1 kHz, The plots ε´(T), ε˝(T) and ε˝(ε´) reveal that these systems exhibit two distinct dielectric relaxations located on either side of a temperature Tm which was found to be equal to about — 20°C in the case of water and lower than — 20°C in the case of aqueous solutions of NH4Cl. The relaxation located in the lower temperature range arises from the Debye dipolar absorption of ice while the other one could be related to structural changes occurring within the lattice of ice as T approaches its melting point. These results are consistent with those obtained by investigating versus frequency the dielectric behaviour of ice monocrystals at discrete sub-zero temperatures close to their melting point.

Predicted β-turns in peptide and glycopeptide anti-freezes

Different regions of peptide and glycopeptide anti-freezes were predicted as β-turns. Most of the polar residues are implicated in such structures. Since a β-turn is characterized by αC i − αC i+3 distance below 7 Å, our results are in excellent agreement with the mechanism previously suggested (1) to explain the wintertime freezing point depression of the blood of anti-freeze fishes: an interaction to the peptide to ice to means of hydrogen binding which implicate that a distance of 4.5 Å separates the polar residues implicated in hydrogen binding with the oxygen in the ice lattice.

Dielectric Behaviour of Ice Microcrystals: A Study Versus Temperature

Abstract Dispersions of ice microcrystals were obtained from the breakdown of super-cooling of water-in-oil type emulsions whose disperse phase was either resin-exchanged water or aqueous solutions of NH4C1. Their complex permittivity ϵ* = ϵ′ - ϵ″ was studied versus their temperature T, up to the melting point of the ice microcrystals, by means of an automatically balancing admittance bridge (General Radio 1680A) working at 400 Hz and 1 kHz. The plots ϵ′(T), ϵ″(T), and ϵ″(ϵ′) reveal that these systems exhibit two distinct dielectric relaxations located on both sides of a temperature T m which was found to be equal to about —20°C in the case of water and lower than —20°C in the case of aqueous solutions of NH4C1. The relaxation located in the lower temperature range arises from the Debye dipolar absorption of ice while the other one could be related to structural changes occurring within the lattice of ice as T approaches its melting point. These results are consistent with those obtained by investigating versus frequency the dielectric behaviour of ice microcrystals, at discrete sub-zero temperatures close to their melting point. This paper has been accepted for publication in full in a forthcoming issue of the Journal of Glaciology.

Dielectric Behaviour of Ice Microcrystals: A Study Versus Temperature

AbstractDispersions of ice microcrystals were obtained from the breakdown of super-cooling of water-in-oil type emulsions whose disperse phase was either resin-exchanged water or aqueous solutions of NH4C1. Their complex permittivity ϵ* = ϵ′ - ϵ″ was studied versus their temperature T, up to the melting point of the ice microcrystals, by means of an automatically balancing admittance bridge (General Radio 1680A) working at 400 Hz and 1 kHz. The plots ϵ′(T), ϵ″(T), and ϵ″(ϵ′) reveal that these systems exhibit two distinct dielectric relaxations located on both sides of a temperature Tm which was found to be equal to about —20°C in the case of water and lower than —20°C in the case of aqueous solutions of NH4C1. The relaxation located in the lower temperature range arises from the Debye dipolar absorption of ice while the other one could be related to structural changes occurring within the lattice of ice as T approaches its melting point. These results are consistent with those obtained by investigating versus frequency the dielectric behaviour of ice microcrystals, at discrete sub-zero temperatures close to their melting point.This paper has been accepted for publication in full in a forthcoming issue of the Journal of Glaciology.