Ideal Ice Research Articles

Imaging surface structure and premelting of ice Ih with atomic resolution.

Ice surfaces are closely relevant to many physical and chemical properties, such as melting, freezing, friction, gas uptake and atmospheric reaction1-8. Despite extensive experimental and theoretical investigations9-17, the exact atomic structures of ice interfaces remain elusive owing to the vulnerable hydrogen-bonding network and the complicated premelting process. Here we realize atomic-resolution imaging of the basal (0001) surface structure of hexagonal water ice (ice Ih) by using qPlus-based cryogenic atomic force microscopy with a carbonmonoxide-functionalized tip. We find that the crystalline ice-Ih surface consists of mixed Ih- and cubic (Ic)-stacking nanodomains, forming periodic superstructures. Density functional theory reveals that this reconstructed surface is stabilized over the ideal ice surface mainly by minimizing the electrostatic repulsion between dangling OH bonds. Moreover, we observe that the ice surface gradually becomes disordered with increasing temperature (above 120 Kelvin), indicating the onset of the premelting process. The surface premelting occurs from the defective boundaries between the Ih and Ic domains and can be promoted by the formation of a planar local structure. These results put an end to the longstanding debate on ice surface structures and shed light on the molecular origin of ice premelting, which may lead to a paradigm shift in the understanding of ice physics and chemistry.

Rational Design of and Mechanism Insight into an Efficient Antifreeze Peptide for Cryopreservation

The development of effective antifreeze peptides to control ice growth has attracted a significant amount of attention yet still remains a great challenge. Here, we propose a novel design method based on in-depth investigation of repetitive motifs in various ice-binding proteins (IBPs) with evolution analysis. In this way, several peptides with notable antifreeze activity were developed. In particular, a designed antifreeze peptide named AVD exhibits ideal ice recrystallization inhibition (IRI), solubility, and biocompatibility, making it suitable for use as a cryoprotective agent (CPA). A mutation analysis and molecular dynamics (MD) simulations indicated that the Thr6 and Asn8 residues of the AVD peptide are fundamental to its ice-binding capacity, while the Ser18 residue can synergistically enhance their interaction with ice, revealing the antifreeze mechanism of AVD. Furthermore, to evaluate the cryoprotection potential of AVD, the peptide was successfully employed for the cryopreservation of various cells, which demonstrated significant post-freezing cell recovery. This work opens up a new avenue for designing antifreeze materials and provides peptide-based functional modules for synthetic biology.

The role of antifreeze glycoprotein (AFGP) and polyvinyl alcohol/polyglycerol (X/Z-1000) as ice modulators during partial freezing of rat livers.

The current liver organ shortage has pushed the field of transplantation to develop new methods to prolong the preservation time of livers from the current clinical standard of static cold storage. Our approach, termed partial freezing, aims to induce a thermodynamically stable frozen state at high subzero storage temperatures (-10°C to -15°C), while simultaneously maintaining a sufficient unfrozen fraction to limit ice-mediated injury. Using glycerol as the main permeating cryoprotectant agent, this research first demonstrated that partially frozen rat livers showed similar outcomes after thawing from either -10°C or -15°C with respect to subnormothermic machine perfusion metrics. Next, we assessed the effect of adding ice modulators, including antifreeze glycoprotein (AFGP) or a polyvinyl alcohol/polyglycerol combination (X/Z-1000), on the viability and structural integrity of partially frozen rat livers compared to glycerol-only control livers. Results showed that AFGP livers had high levels of ATP and the least edema but suffered from significant endothelial cell damage. X/Z-1000 livers had the highest levels of ATP and energy charge (EC) but also demonstrated endothelial damage and post-thaw edema. Glycerol-only control livers exhibited the least DNA damage on Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining but also had the lowest levels of ATP and EC. Further research is necessary to optimize the ideal ice modulator cocktail for our partial-freezing protocol. Modifications to cryoprotective agent (CPA) combinations, including testing additional ice modulators, can help improve the viability of these partially frozen organs.

Ice thickness monitoring for cryo-EM grids by interferometry imaging

While recent technological developments contributed to breakthrough advances in single particle cryo-electron microscopy (cryo-EM), sample preparation remains a significant bottleneck for the structure determination of macromolecular complexes. A critical time factor is sample optimization that requires the use of an electron microscope to screen grids prepared under different conditions to achieve the ideal vitreous ice thickness containing the particles. Evaluating sample quality requires access to cryo-electron microscopes and a strong expertise in EM. To facilitate and accelerate the selection procedure of probes suitable for high-resolution cryo-EM, we devised a method to assess the vitreous ice layer thickness of sample coated grids. The experimental setup comprises an optical interferometric microscope equipped with a cryogenic stage and image analysis software based on artificial neural networks (ANN) for an unbiased sample selection. We present and validate this approach for different protein complexes and grid types, and demonstrate its performance for the assessment of ice quality. This technique is moderate in cost and can be easily performed on a laboratory bench. We expect that its throughput and its versatility will contribute to facilitate the sample optimization process for structural biologists.

A Microfluidic Device for Automated High Throughput Detection of Ice Nucleation of Snomax®.

Measurement of ice nucleation (IN) temperature of liquid solutions at sub-ambient temperatures has applications in atmospheric, water quality, food storage, protein crystallography and pharmaceutical sciences. Here we present details on the construction of a temperature-controlled microfluidic platform with multiple individually addressable temperature zones and on-chip temperature sensors for high-throughput IN studies in droplets. We developed, for the first time, automated droplet freezing detection methods in a microfluidic device, using a deep neural network (DNN) and a polarized optical method based on intensity thresholding to classify droplets without manual counting. This platform has potential applications in continuous monitoring of liquid samples consisting of aerosols to quantify their IN behavior, or in checking for contaminants in pure water. A case study of the two detection methods was performed using Snomax® (Snomax International, Englewood, CO, USA), an ideal ice nucleating particle (INP). Effects of aging and heat treatment of Snomax® were studied with Fourier transform infrared (FTIR) spectroscopy and a microfluidic platform to correlate secondary structure change of the IN protein in Snomax® to IN temperature. It was found that aging at room temperature had a mild impact on the ice nucleation ability but heat treatment at 95 °C had a more pronounced effect by reducing the ice nucleation onset temperature by more than 7 °C and flattening the overall frozen fraction curve. Results also demonstrated that our setup can generate droplets at a rate of about 1500/min and requires minimal human intervention for DNN classification.

Ice Ic without stacking disorder by evacuating hydrogen from hydrogen hydrate

Water freezes below 0 °C at ambient pressure ordinarily to ice Ih, with hexagonal stacking sequence. Under certain conditions, ice with a cubic stacking sequence can also be formed, but ideal ice Ic without stacking-disorder has never been formed until recently. Here we demonstrate a route to obtain ice Ic without stacking-disorder by degassing hydrogen from the high-pressure form of hydrogen hydrate, C2, which has a host framework isostructural with ice Ic. The stacking-disorder free ice Ic is formed from C2 via an intermediate amorphous or nano-crystalline form under decompression, unlike the direct transformations occurring in ice XVI from neon hydrate, or ice XVII from hydrogen hydrate. The obtained ice Ic shows remarkable thermal stability, until the phase transition to ice Ih at 250 K, originating from the lack of dislocations. This discovery of ideal ice Ic will promote understanding of the role of stacking-disorder on the physical properties of ice as a counter end-member of ice Ih.

Interlaboratory Study of Ice Adhesion Using Different Techniques

Low ice adhesion surfaces are a promising anti-icing strategy. However, reported ice adhesion strengths cannot be directly compared between research groups. This study compares results obtained from testing the ice adhesion strength on two types of surfaces at two different laboratories, testing two different types of ice with different ice adhesion test methods at temperatures of −10 and −18 °C. One laboratory used the centrifuge adhesion test and tested precipitation ice and bulk water ice, while the other laboratory used a vertical shear test and tested only bulk water ice. The surfaces tested were bare aluminum and a commercial icephobic coating, with all samples prepared in the same manner. The results showed comparability in the general trends, surprisingly, with the greatest differences for bare aluminum surfaces at −10 °C. For bulk water ice, the vertical shear test resulted in systematically higher ice adhesion strength than the centrifugal adhesion test. The standard deviation depends on the surface type and seems to scale with the absolute value of the ice adhesion strength. The experiments capture the overall trends in which the ice adhesion strength surprisingly decreases from −10 to −18 °C for aluminum and is almost independent of temperature for a commercial icephobic coating. In addition, the study captures similar trends in the effect of ice type on ice adhesion strength as previously reported and substantiates that ice formation is a key parameter for ice adhesion mechanisms. Repeatability should be considered a key parameter in determining the ideal ice adhesion test method.

Preparation of ice microspheres and their application in the preparation of porous poly(l-lactic acid) (PLLA) scaffolds

Pure ice particles have been used as porogens to prepare bone tissue engineering scaffolds for several years. However, it is difficult to prepare an ideal spherical ice porogen to improve the pore structure of the porous scaffolds. In this work, sublimable ice-based microspheres were prepared by spraying the 1,4-dioxane/water (70/30, v/v) solution through a syringe needle into liquid nitrogen. Ice-based microspheres have suitable melting points (− 4 °C) and high sublimation rate. The sieved ice-based microspheres with a size of 380–500 μm were used as a porogen to prepare porous PLLA scaffold. The calculation results show that the surface tension of the solution and the interfacial tension between the solution and liquid nitrogen are small when the volume ratio of the 1,4-dioxane/water is 70/30. The 1,4-dioxane/water solution can be effectively dispersed into small droplets in liquid nitrogen and rapidly frozen into microspheres. Scanning electron microscope images show that the porous PLLA scaffold had good pore connectivity. Macropores and micropores can be observed in the cross section of the PLLA scaffold. The pore wall has a special rough structure, and many micro-/nano-PLLA fibers can be found on the surface of the pore wall.

On the heterogeneous nucleation of mesospheric ice on meteoric smoke particles: Microphysical modeling

Meteor smoke particles (MSP), which are thought to be the nucleation germs for mesospheric ice, are currently discussed to consist of highly absorbing materials such as magnesiowüstite, hematite or magnesium–iron-silicates and may therefore be warmer than the ambient atmosphere. In order to quantify the temperature difference between MSP and the atmosphere we developed a model to calculate the MSP equilibrium temperature in radiational and collisional balance. The temperature difference between MSP and the surrounding atmosphere strongly depends on the composition of the MSP, especially on the relative iron content, where a higher iron content leads to warmer MSP. We then derive an expression of the nucleation rate of mesospheric ice particles which explicitly accounts for this temperature difference. We find that the nucleation rate is strongly reduced by several orders of magnitude if the germ temperature is increased by only a few Kelvin. Implementing this nucleation rate depending on the germ temperature into CARMA, the Community Aerosol and Radiation Model for Atmospheres, we find that fewer but larger ice particles are formed compared to a reference scenario with no temperature difference between MSP and ambient atmosphere. This may indicate that iron-rich MSP are not ideal ice nuclei and that either other MSP-types or other nucleation pathways (e.g. wave induced heterogeneous nucleation or even homogeneous nucleation) are responsible for ice formation at the mesopause.

Ionization of Nitric Acid on Crystalline Ice: The Role of Defects and Collective Proton Movement.

Ionization of nitric acid (HNO3) on a model ice surface is studied using ab initio molecular dynamics at temperatures of 200 and 40 K with a surface slab model that consists of the ideal ice basal plane with locally optimized and annealed defects. Pico- and subpicosecond ionization of nitric acid can be achieved in the defect sites. Key features of the rapid ionization are (a) the efficient solvation of the polyatomic nitrate anion, by stealing hydrogen bonds from the weakened hydrogen bonds at defect sites, (b) formation of contact ion pairs to stable "presolvated" molecular species that are present at the defects,

Ice radar investigation at Dome A, East Antarctica: Ice thickness and subglacial topography

Dome A, located in the central East Antarctic ice sheet (EAIS), is the highest summit of the Antarctic ice sheet. From ice-sheet evolution modeling results, Dome A is likely to preserve over one million years of the Earth’s paleo-climatic and -environmental records, and considered an ideal deep ice core drilling site. Ice thickness and subglacial topography are critical factors for ice-sheet models to determine the timescale and location of a deep ice core. During the 21st and 24th Chinese National Antarctic Research Expedition (CHINARE 21, 2004/05; CHINARE 24, 2007/08), ground-based ice radar systems were used to a three-dimensional investigation in the central 30 km×30 km region at Dome A. The successfully obtained high resolution and accuracy data of ice thickness and subglacial topography were then interpolated into the ice thickness distribution and subglacial topography digital elevation model (DEM) with a regular grid resolution of 140.5 m×140.5 m. The results of the ice radar investigation indicate that the average ice thickness in the Dome A central 30 km×30 km region is 2233 m, with a minimal ice thickness of 1618 m and a maximal ice thickness of 3139 m at Kunlun Station. The subglacial topography is relatively sharp, with an elevation range of 949–2445 m. The typical, clear mountain glaciation morphology is likely to reflect the early evolution of the Antarctic ice sheet. Based on the ice thickness distribution and subglacial topography characteristics, the location of Kunlun Station was suggested to carry out the first high-resolution, long time-scale deep ice core drilling. However, the internal structure and basal environments at Kunlun Station still need further research to determine.

Quality evaluation of quick-frozen biological specimens by simultaneous microbeam SAXS/WAXS recordings

The quality of small-angle X-ray scattering (SAXS) patterns from quick-frozen hydrated biological specimens was correlated with the extent of ice crystal formation by simultaneously recording wide-angle X-ray scattering (WAXS) of ice, at a micrometer-order spatial resolution by using X-ray microbeams. Flight muscle fibers from a giant waterbug, Lethocerus, known to generate well defined small-angle reflection spots originating from the hexagonal lattices of myofilaments, were quick-frozen in the presence or absence of various cryoprotectants. Freezing without a cryoprotectant resulted in massive ice-crystal formation at almost all depths of the specimen, and the occurrence of reflection spots was limited to the region close to the specimen surface. Inclusion of 20% dimethyl sulfoxide or methylpentanediol ensured ideal vitreous ice formation and good diffraction qualities for up to 100 microm from the specimen surface. Glycerol and sucrose were found to be inferior at a 20% concentration, but left the reflection spots observable at depths of up to 100 microm. Thus, the microbeam SAXS/WAXS recording offers a high-spatial-resolution means of evaluating the extent of structure preservation of quick-frozen biological specimens. The technique presented here may also provide useful information in cryoelectron microscopy.

When Metal Meets Ice: Potential for Performance or Injury

Abstract Physical conditioning, technical ability, contact, and protective equipment have been identified through research as factors that can potentially contribute to the incidence of injuries in ice hockey players. One safety-related factor often overlooked is the interaction between the skate blade and the ice. Skating is one of the fundamental skills of a successful hockey player, but the effect of skate sharpening on blade characteristics and performance has received limited research attention. The point of contact with the ice is essentially what allows the transition of human motion to skating mechanics, and it may affect both the quality of skating performance and the potential for on-ice injuries. The purpose of this paper is to address the influence of skate blade sharpening characteristics on performance. Experiments performed to examine skate blade sharpening characteristics have identified radius of hollow (ROH), radius of contour (ROC), pitch and levelness of edges as variables that can be manipulated, quantified, and controlled when analyzing blade-ice interaction and the effect of skate sharpening on skating performance. Optimum values for each may produce more effective skating performances. Less than optimum values can result in slower speeds, longer stopping times, instability, body malalignment, greater fatigue, and potentially, greater chance of injury. Being able to define blade characteristics and determine the best combination of ROH, ROC, and pitch for a specific player allows some degree of control in an environment which can often be unpredictable. Furthermore, although there are standards for acceptable ice in professional hockey leagues, very often players must skate on a surface which is not only less than ideal, but which can also change over the course of a game or practice. Careful sharpening to accommodate for less than ideal ice conditions and the unpredictable nature of the play may also help to prevent fatigue, and injuries.

Adsorption of acetic acid on ice: Experiments and molecular dynamics simulations

Adsorption study of acetic acid on ice surfaces was performed by combining experimental and theoretical approaches. The experiments were conducted between 193 and 223 K using a coated wall flow tube coupled to a mass spectrometric detection. Under our experimental conditions, acetic acid was mainly dimerized in the gas phase. The surface coverage increases with decreasing temperature and with increasing concentrations of acetic acid dimers. The obtained experimental surface coverages were fitted according to the BET theory in order to determine the enthalpy of adsorption deltaH(ads) and the mololayer capacity N(M(dimers)) of the acetic acid dimers on ice: deltaH(ads) = (-33.5 +/- 4.2) kJ mol(-1), N(M(dimers)) = (l1.27 +/- 0.25) x 10(14) dimers cm(-2). The adsorption characteristics of acetic acid on an ideal ice I(n)(0001) surface were also studied by means of classical molecular dynamics simulations in the same temperature range. The monolayer capacity, the configurations of the molecules in their adsorption sites, and the corresponding adsorption energies have been determined for both acetic acid monomers and dimers, and compared to the corresponding data obtained from the experiments. In addition, the theoretical results show that the interaction with the ice surface could be strong enough to break the acetic acid dimers that exist in the gas phase and leads to the stabilization of acetic acid monomers on ice.

Mechanisms for pressure- and time-dependent amorphization of ice under pressure

Amorphization of hexagonal ice under pressure at low temperatures has been studied by measuring the thermal conductivity with time, by keeping the ice in the temperature range $127--130\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and pressure range $0.79--0.88\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$. The results have been used to examine the relative merits of the Lindemann melting and the Born instability as a mechanism for amorphization of ice. Thermal conductivity decreases continuously with time according to a stretched-exponential relation. This and the findings that, (i) amorphization pressure is lower than the available values calculated for an ideal ice crystal by using the Born theory, and (ii) amorphization of cubic ice occurs at about the same pressure as that of hexagonal ice, seem inconsistent with both mechanisms. The findings can be reconciled with the Born mechanism if the effect of the existing lattice faults and/or the lattice faults produced during the plastic deformation of uniaxially compressed ice are considered to produce a distribution of collapse pressure. It is argued that the difference between the amorphization and the low-density amorph to high-density amorph transformation pressures corresponds to the energy needed to collapse, or randomly distort, the ice crystallites to a structure whose energy spontaneously decreases by diffusion of a ${\mathrm{H}}_{2}\mathrm{O}$ molecule into the first coordination shell of the amorph's known structure, and persist there as an interstitial molecule. The newly observed amorphization kinetics has a bearing on the computer-simulated inference on pressure-induced collapse and/or melting of crystals.

Neutron scattering investigation of the spin ice state inDy2Ti2O7

Dy2Ti2O7 has been advanced as an ideal spin ice. We present a neutron scattering investigation of a sample of 162Dy2Ti2O7. The scattering intensity has been mapped in zero applied field in the hhl and hk0 planes at temperatures between 0.05 K and 20 K. The measured diffuse scattering (in the static approximation) has been compared to that predicted by the dipolar spin ice model. The comparison is good, except at the Brillouin zone boundaries where extra scattering appears in the experimental data. It is concluded that the dipolar spin ice model provides a successful basis for understanding Dy2Ti2O7, but that there are issues which remain to be clarified.

Ammonia adsorption on and diffusion into thin ice films grown on Pt(111).

Ammonia adsorption on and diffusion into thin ice films grown on a Pt(111) surface were studied using Fourier transform infrared spectroscopy (FTIR) and thermal desorption spectroscopy. After exposing the crystalline ice film to ammonia molecules at 45 K (ammonia/ice film), we have detected an intriguing feature at 1470 cm(-1) in the FTIR spectra, which is derived from the adsorption of ammonia on the ice with a characteristic structure which appears in thin film range. The peak intensity of this feature decreases gradually as the thickness of the substrate ice increases. In addition, we have detected a feature at 1260 cm(-1) which appears after annealing the ammonia/ice film. The feature corresponds to the ammonia molecules which reach the ice/Pt(111) interface through the ice film. Intriguingly, the intensity of this feature decreases with the ice thickness and there is a linear relation of the peak intensity of the features at 1470 and 1260 cm(-1). We propose a model in which the solubility of the ammonia molecules is much higher for the thin ice film than that for the ideal ice.

Adsorption and Diffusion of Ammonia on Ice/Pt(111) Surface

Adsorption and diffusion of ammonia on an ice/Pt(111) surface were studied using Fourier transform infrared spectroscopy (FTIR) and thermal desorption spectroscopy (TDS). After exposing the crystalline ice film to ammonia molecules at 45 K, we have detected an intriguing feature at 1470 cm−1 in the FTIR spectra. This feature is derived from the ammonia adsorption on the ice with a characteristic structure which appears in thin film region. The peak intensity decreases gradually as the thickness of the substrate ice increases. In addition, we have detected a feature at 1260 cm−1 that appears after flashing the film to 113 K. The feature corresponds to the ammonia molecules which penetrate the ice surface and reach the ice/Pt(111) interface. Intriguingly, the intensity of this feature decreases with the ice thickness and there is a linear relation of the peak intensity of the features at 1470 cm−1 and 1260 cm−1. We propose a model that the solubility of the ammonia molecules is much higher for the thin ice film, whose structure is deformed from the ideal ice due to the presence of the metal substrate, than that for the ideal ice.

Dichotomous collective proton dynamics in ice

The collective proton dynamics in ice is studied on the basis of the two-dimensional (2D) nonlinear lattice model which takes the dichotomous branching of proton transfers in hydrogen-bonded networks into account. The essential point of this model is that the network topology of the square proton lattice satisfies the Bernal-Fowler ice rules of the 3D ice crystal structure. The model is considered as a straightforward extension of the standard 1D coupled double-well oscillator model described by the discrete nonlinear Klein-Gordon equation to two dimensions while imposing the ice rules. This generalization under the ice constraints has been shown to be unique. A relation between the boundary conditions and topological charge (like Gauss' law) is established. For any domain of the square ice lattice with nonzero topological charge and an ideal ice configuration chosen randomly on its boundary, the extended positive $({\mathrm{H}}_{3}{\mathrm{O}}^{+})$ and negative $({\mathrm{OH}}^{\mathrm{\ensuremath{-}}})$ ionic defects are described in terms of 2D vector topological solitons. The definition of the 2D kinks and antikinks is given by using Gauss' law. An anisotropic generalization of the 2D ice model and an appropriate numerical scheme allows us to study the dynamical properties of the 2D solitons in comparison with the corresponding 1D solutions. Particularly, contrary to the 1D case, the existence of a nonzero Peierls-Nabarro relief has been proved to exist in all cases, even if intersite proton-proton interactions are infinitely strong, so that the free 2D soliton dynamics is impossible in the ice crystal. On the other hand, our studies of the thermalization of the 2D ice lattice clearly demonstrate the crucial role of the cooperativity of hydrogen bonding in the nucleation and dynamics of the defect pairs ${\mathrm{H}}_{3}{\mathrm{O}}^{+}$ and ${\mathrm{OH}}^{\mathrm{\ensuremath{-}}},$ explaining their very low density known from experimental data in ice physics.

ボブスレー・リュージュトラックの製氷システム

Bobsleigh and Luge Track of the Nagano Winter Olympic Games which will be held in February 1998 is the 14th one in the world as a system of chilling and icing the entire track with refrigerators. The Nagano's system is the first one in the world as a system of indirectly chilling the track by using brine which is ethylene glycol. The system of the other tracks is a system of directly chilling by expanding ammonia. Mitsubishi Heavy Industries, LTD (MHI) has designed and constructed an ideal ice making system which had refrigerators, pumps, a cooling piping, an automatic control system, and MHI original Distributed Control System (DCS) by thermal dynamic simulation of the track. Optical communication was applied to the DCS in order to connect to thirteen control stations, which were located along the track 1.7km in length. Applying optical communication to the DCS, MHI realized the reliable DCS with anti-electromagnetic interference against, for example Lightning.