Regular Ice Research Articles

Spin ice and other frustrated magnets on the pyrochlore lattice

The recent identification of the dysprosium titanate compound Dy 2Ti 2O 7 as a “Spin ice”, i.e. the spin analog of regular entropic ice of Pauling, has created considerable excitement. The ability to manipulate spins using magnetic fields gives a unique advantage over regular ice in these systems, and has been used to study the recovery of entropy. Predicted magnetization plateaus have been observed, testing the underlying model consisting of a competition between short-ranged super exchange, and long-ranged dipolar interactions between spins. I discuss other compounds that are possibly spin ice like: Ho 2Ti 2O 7, and the two stannates Ho 2Sn 2O 7, Dy 2Sn 2O 7.

Analysis of Ice-Binding Sites in Fish Type II Antifreeze Protein by Quantum Mechanics

Many organisms living in cold environments can survive subzero temperatures by producing antifreeze proteins (AFPs) or antifreeze glycoproteins. In this paper we investigate the ice-binding surface of type II AFP by quantum mechanical methods, which, to the best of our knowledge, represents the first time that molecular orbital computational approaches have been applied to AFPs. Molecular mechanical approaches, including molecular docking, energy minimization, and molecular dynamics simulation, were used to obtain optimal systems for subsequent quantum mechanical analysis. We selected 17 surface patches covering the entire surface of the type II AFP and evaluated the interaction energy between each of these patches and two different ice planes using semi-empirical quantum mechanical methods. We have demonstrated the weak orbital overlay phenomenon and the change of bond orders in ice. These results consistently indicate that a surface patch containing 19 residues (K37, L38, Y20, E22, Y21, I19, L57, T56, F53, M127, T128, F129, R17, C7, N6, P5, G10, Q1, and W11) is the most favorable ice-binding site for both a regular ice plane and an ice plane where water O atoms are randomly positioned. Furthermore, for the first time the computation results provide new insights into the weakening of the ice lattice upon AFP binding, which may well be a primary factor leading to AFP-induced ice growth inhibition.

Evaluation of a 45° Slant Quasi-Linear Radar Polarization State for Distinguishing Drizzle Droplets, Pristine Ice Crystals, and Less Regular Ice Particles

Abstract A remote sensing capability is needed to detect clouds of supercooled, drizzle-sized droplets, which are a major aircraft icing hazard. Discrimination among clouds of differing ice particle types is also important because both the presence and type of ice influence the survival of liquid in a cloud and the chances for occurrence of these large, most hazardous droplets. This work shows how millimeter-wavelength dual-polarization radar can be used to identify these differing hydrometeors. It also shows that by measuring the depolarization ratio (DR), the estimation of the hydrometeor type can be accomplished deterministically for drizzle droplets; ice particles of regular shapes; and to a considerable extent, the more irregular ice particles, and that discrimination is strongly influenced by the polarization state of the transmitted microwave radiation. Thus, appropriate selection of the polarization state is emphasized. The selection of an optimal polarization state involves trade-offs in competing factors such as the functional dynamic range of DR, sensitivity to low-reflectivity clouds, and insensitivity to oscillations in the settling orientations of ice crystals. A 45° slant, quasi-linear polarization state, one in which only slight ellipticity is introduced, was found to offer a very good compromise, providing considerable advantages over standard horizontal and substantially elliptical polarizations. This was determined by theoretical scattering calculations that were verified experimentally in field measurements conducted during the Mount Washington Icing Sensors Project (MWISP). A selectable-dual-polarization Ka-band (8.66-mm wavelength) radar was used. A wide variety of hydrometeor types was sampled. Clear differentiation among planar crystals, columnar crystals, and drizzle droplets was achieved. Also, differentiation among crystals of fundamentally different shapes (aspect ratios) within each of the planar and columnar families was found possible. These distinctions matched calculations of DR, usually to within 1 or 2 dB. The results from MWISP and from previous experiments with other polarizations have demonstrated that the agreement between theory and measurements by this method is repeatable. Additionally, although less rigorously predicted by theory, the field measurements demonstrated substantial differentiation among the more irregular and more spherical ice particles, including aggregates, elongated aggregates, heavily rimed dendrites, and graupel. Measurable separation between these various irregular ice particle types and drizzle droplets was also verified.

Textural analysis of fat reduced vanilla ice cream products

Sensory and instrumental analyses were used to evaluate the texture of regular (10%), light (5%), low fat (2.5%) and fat free vanilla (0.4%) ice creams. The light, low fat and fat free ice cream were prepared using a modified pea starch as the fat replacement ingredient. Two processing trials with continuous commercial-like process conditions were undertaken. While the sensory attributes of the light sample were comparable to the regular vanilla ice cream, the trained sensory panel rated the low fat and fat free ice creams to have lower viscosity, smoothness and mouth coating properties. Instrumentally determined apparent viscosity data supported the sensory data. There was good correlation between the instrumentally determined firmness values and the sensory results for firmness. The use of modified starch as a partial fat replacer in vanilla ice cream was demonstrated.

Effect of freezing conditions and storage on ice crystal and drip volume in turbot ( Scophthalmus maximus) : Evaluation of pressure shift freezing vs. air-blast freezing

Turbot fillets were frozen either by pressure shift freezing (PSF, 140 MPa, −14°C) or by air-blast freezing (ABF), and then stored at −20°C for 75 days. Smaller and more regular intracellular ice crystals were observed in fillets frozen by PSF compared with air-blast frozen ones. Ice crystals area in PSF samples was approximately 10 times smaller than that of ABF samples, on average. The PSF process reduced thawing drip compared with air-blast freezing. Conversely to this classical freezing process, the storage time did not adversely influence the thawing drip of PSF samples. In addition, PSF appeared to reduce cooking drip after 45 days of storage at −20°C. Differential scanning calorimetry analysis showed a significant reduction of the total enthalpy of denaturation for the pressure shift frozen samples compared to fresh and conventional frozen samples. Besides, a new melting transition appeared on the thermogram of PSF samples at approximately +40°C.

An examination of the distribution of snow on sea‐ice

Snow on sea‐ice is an integral, yet poorly understood, component of the ocean‐sea‐ice‐atmosphere interface. Snow exerts a significant control on both shortwave and conductive fluxes due to its high albedo and low thermal conductivity. Parameters pertaining to snow distribution and/or thickness are hard to model and/or to measure using geospatial techniques. In terms of Arctic hydrology, we consider three aspects of snow important to understanding processes operating within the ocean‐sea‐ice‐atmosphere interface: i) the average magnitude of snow thickness on sea‐ice; ii) the spatial distribution of snow as a function of location and ice type; and iii) the seasonal evolution of both magnitude and distribution. In this paper we focus on the second aspect; distribution. The distribution patterns of snow over first‐year (FYI), multiyear (MYI) and rubble (RI) sea‐ice were evaluated at 15 sites, sampled during two years of field research in the Canadian Arctic. A geostatistical technique known as the variogram was used to model the statistical pattern of the snow distribution. The significance of different snow distribution patterns was then evaluated using a radiative transfer model under various snow and ice type distributions. Results of this study indicate that the variogram provided a good estimate of the type and change of spatial dependence of snow depths over various types of sea‐ice. Over FYI, the regular smooth ice topography produced a periodicity in the snow drifts which was best estimated using a wave (hole‐effect) theoretical variogram in combination with a Gaussian model. The more uneven ice topographies characteristic of MYI and RI produced a more irregular snow drift pattern. The most appropriate models were a combination of the spherical and Gaussian variogram models (MYI sites) or a single Gaussian model (RI sites). The nugget values of the variograms increased as the sea‐ice topography became more irregular (smooth FYI to large uplifted ice pieces in RI). This was attributed to the presence of snow drifts in the MYI and RI sites that were less than the sampling interval. Geometric anisotropy was present in all 15 sites, indicating a directional trend in the spatial continuity of the snow distribution patterns which we attribute to the prevailing wind direction during depositional storm events. The ramifications of the snow distribution as a function of ice type were illustrated by the transmission of photosynthetically active radiation (PAR) through the three ice types. As the ice topography becomes more irregular, the areally averaged transmission of PAR decreases, thereby illustrating the non‐linear nature of the relationship between PAR extinction and snow thickness. The findings of this case study suggest that by knowing the type of sea‐ice we can make predictions about the statistical pattern of the associated snow distribution. More importantly, the main finding suggests that this snow distribution pattern will dominate the areally averaged transmission of PAR across the ocean‐sea‐ice‐atmosphere interface.

The double-pyramid structure of dendritic ice growing from supercooled water

It is known that ice growing freely from supercooled water has a morphological transition at T=−2.7°C, from a flat dendritic structure at higher temperatures to a twelve-sided double-pyramid structure at lower temperatures. The double-pyramid structure, which can be described as two hollow six-sided pyramids joined at their apices, is built from dendrites growing in well-defined growth directions which are noncrystallographic in the planes normal to the basal plane while their projections on the basal plane retain the hexagonal symmetry. Similar structures have been reported in other hexagonal materials. In order to understand the growth mechanism better, we measured the temperature field in the water around the growing crystals by using the temperature dependence of its refractive index. Since this dependence happens to be zero at the freezing point for regular water (H 2O), we use heavy water (D 2O), and achieve considerably greater sensitivity. The free growth experiments performed with heavy ice reveal that their morphological behavior is similar to regular ice, as well as their velocities and the angle between the pyramids as a function of supercooling. The temperature measurements showed that the interaction between the two sides of the pyramid via the temperature field is weak. This leads to the conclusion that the solution for the growth mode of the dendrites should be found in the single dendrite level. Explanations of this phenomenon are discussed in the light of recent advances in dendritic growth theory – in particular the concept of microscopic solvability – combined with the behavior of the surface tension and the kinetic effect as a function of crystallographic orientation. It can be shown that growth in a low symmetry direction leads to an asymmetrically growing crystal and to asymmetry in the observed temperature field.

Acceptability of fat-modified foods to children, adolescents and their parents: Effect of sensory properties, nutritional information and price

The effects of sensory properties, nutrition information (NI) and price (P) on the acceptability of eight fat-modified foods were investigated in 30 families with children (ages 6–10), adolescents (ages 12–15) and both parents. Liking was measured blind with a 7-point hedonic scale (DOL) and by preference ranking. Purchase intent was then measured on a 5-point scale, first with NI and then with NI and P available. DOL did not differ across fat levels for any of the products, except for the regular ice cream which was liked more by mothers. Yet, fathers preferred the regular version over the low-fat or fat-free ones for milk, cheese, mayonnaise, hot dog and ice cream. Mothers were more willing to purchase the low-fat version than the regular one for milk, mayonnaise and pastry. Fathers were not willing to pay more for the fat-free foods that were more expensive. The purchase intentions of children and adolescents were driven mainly by their liking for the foods.

Sensitivity of cirrus cloud albedo, bidirectional reflectance and optical thickness retrieval accuracy to ice particle shape

We examine the sensitivity of cirrus cloud albedo and bidirectional reflection function to particle shape using the phase functions of liquid water spheres, regular hexagonal ice crystals, and random‐fractal ice particles calculated at a nonabsorbing visible wavelength of 0.63 μm. Accurate multiple‐scattering calculations for plane‐parallel clouds show that hexagonal ice crystal clouds have systematically larger planetary and global albedos than liquid water clouds of the same optical thickness. There is accumulating evidence that the idealized phase function of regular hexagonal crystals, which causes pronounced halos, is not necessarily the best representation of the range of reflectance characteristics of the majority of ice clouds. A more typical representation of the scattering phase function for ice clouds that are composed of a complex set of crystal shapes and sizes may be obtained using a model of randomly shaped irregular particles. Even larger cloud albedos are obtained for the random‐fractal particle model because of its smaller asymmetry parameter. Our computations also show that a larger planetary albedo does not always imply a larger reflectance and that the relative brightness of ice versus liquid water clouds is highly scattering‐geometry dependent. Use of the wrong particle shape model (crystal instead of water droplet and vice versa) in retrieving cloud optical thickness from bidirectional reflectance measurements can result in an underestimation or overestimation of the true optical thickness by a factor that can exceed 3. At some scattering geometries, use of the wrong model can give an unrealistically large optical thickness or no solution at all. Overall, bidirectional reflectance differences between random‐fractal and regular hexagonal particle shapes are significantly smaller than those between either ice crystal and liquid water spheres, except at the back scattering direction.

Conjugated Linoleic Acid Concentrations in Dairy Products as Affected by Processing and Storage

ABSTRACTTotal conjugated linoleic acid (CLA) concentrations increased 1.32 fold in salted and 1.27 in unsalted butter but did not alter the ratio of 9‐cis 11‐trans to total CLA. Nonfat yogurt showed an increase in CLA content with processing (5.25 mg total CLA/g fat) compared to unprocessed raw material (4.40 mg CLA/g fat). No changes in CLA content was observed in processed dairy products such as lowfat yogurt, regular yogurt, lowfat and regular ice cream, sour cream or cheeses such as Mozzarella, Gouda and Cheddar. Storage did not affect CLA concentration in any products suggesting that CLA is a stable component.

Development of the left ventricular hypertrophy and dilation in adolescent ice hockey players evaluated with echocardiography

Computerized echocardiography at rest was used to follow up the dynamics of left heart enlargement in adolescent ice hockey players aged 11 to 15 years. The first year of strength‐endurance training did not lead to any remarkable change of echocardiographic parameters of the left heart ventricular size. A slight tendency to left ventricular hypertrophy appeared after 2 years of training, becoming more marked and significant after the third and fourth years of training. First signs of dilation of the left ventricle were observed after 3 year of training, but it was only after the fourth year of training that there appeared significant evidence. The measured absolute value and the value relative to anthropometric parameters generally produced the same results with a slightly different significance between specifically compared variables. A measurable physiologic enlargement of the heart following regular ice hockey training may be expected in adolescent boys after 3 to 4 years of training.

High-fat foods and the risk of lung cancer.

We conducted a population-based case-control study of the association of dietary cholesterol and fat with lung cancer between 1983 and 1985 on Oahu, Hawaii. The study population included 226 men and 100 women with lung cancer, and 597 male and 268 female community controls matched for age (+/- 5 years) and sex. There was a positive dose-response relation between the consumption of processed meats (luncheon meats, bacon, sausage), dairy foods (whole milk, regular ice cream), eggs, and particular desserts (fruit pies, custard/cream pies) and the risk of lung cancer in men. We also found a positive trend in the risk of lung cancer in women with increasing intake of some processed meats (bacon, Spam) and desserts (cakes, custard/cream pies). The dose-response relation tended to be stronger among men who were heavy smokers and who were diagnosed with squamous cell cancer of the lung. A positive trend in risk was found for nitrite intake in men and dimethylnitrosamine intake in men and women. These data indicate that smokers with a high intake of foods rich in fat and animal protein or who have a preference for cured meats are at increased risk of lung cancer.

The impact of air temperature on old Norwegian ice exporting

In Norway ample ice production was possible every year, but regular ice exporting was restricted to areas with low winter temperatures, particularly from parts of East Norway. The demand for ice fluctuated with air temperatures in the importing countries. While ice exporting to Great Britain increased continually until the turn of the century, ice exporting to Germany had a few dramatic peaks caused by mild winters.

Sodium Concentration of Selected Dairy Products and Acceptability of a Sodium Substitute in Cottage Cheese

Twenty-five samples of cottage cheese collected from processors and local markets in Tennesse in a 2-day period contained an average of 4.57mg sodium/g. Samples collected over longer time had an average concentration of 3.78mg sodium/g, and lowfat cottage cheese had an average of 3.22 mg/g. Buttermilk contained an average of 1.14mg sodium/g; regular vanilla ice cream averaged .83 mg/g, and “no stabilizer added” vanilla ice cream had an average of .59 mg/g. Sodium in lowfat chocolate milk averaged .83 mg/g and French onion dip 5.33 mg/g. One brand of yogurt contained .76 mg/g and another brand 1.69 mg/g.A salt substitute containing equal concentrations of sodium chloride and potassium chloride was used in the creaming mixture for cottage cheese. Taste panel results showed that cottage cheese containing 1.26% sodium chloride, 1.26% salt substitute, or .63% of each had similar flavor scores.

Evolution of the Santa Lucia Fir (Abies bracteata) Ecosystem

Abies scherrii Axelrod is described from the Miocene of western Nevada, and it resembles the living A. bracteata of the Santa Lucia Mountains, coast-central California, a unique endemic representing the sole member of the subgenus Pseudotorreya. Although the fossil species A. chaneyi Mason and A. longirostris Knowlton have previously been considered allied to A. bracteata, those species are extinct, they are not closely allied to bracteata, and they are only distantly related to living Asian firs. A. scherrii occupied an ecotone between broadleaved evergreen sclerophyll forest and mixed conifer forest during the Miocene in western Nevada, and its descendant A. bracteata has a similar occurrence today. The Miocene communities were much richer than the living, including species whose nearest descendants occur only in regions with summer rainfall, or now occupy more restricted areas in California. The latter include Sequoiadendron of the central and southern Sierra Nevada, species of Chamaecyparis and Picea that are confined to the Klamath-Siskiyou region of northwestern California, and species of Abies and Pinus that are largely subalpine in the Sierra Nevada. Abies scherrii and its associates shifted coastward as colder and drier climate developed over the interior. Abies bracteata has survived in a near-coastal climate where evaporation rate is not so high as in the interior or in areas to the south, and where it is largely removed from regular heavy winter snow and ice. Some of its associates were segregated into their present areas as the summer-dry Mediterranean climate emerged in the Quaternary. Sequoiadendron was confined to the relatively drier and sunnier central and southern Sierra Nevada where there was sufficient light in an open forest to enable it to reproduce. Chamaecyparis and Picea were restricted to the northwest sector where there is a longer precipitation season, some summer rain, and where evaporation rate is lower than in the Sierra. Present subalpine species of Abies, Pinus and Tsuga were eliminated from the mixed conifer forest in the Sierra Nevada as evaporation rate increased during slummer and produced conditions inimical for seedling establishment, though they still persist in the upper mixed conifer forest in moister, more equable areas to the northwest. A. bracteata may have had a wider distribution in the Coast Ranges during the moister phases of the Quaternary, together with the mixed conifer forest species. It was apparently restricted with them as drier, hotter climates spread during the later postglacial periods.

Generalized Ferroelectric Model on a Square Lattice

A completely general square‐lattice ferroelectric model is considered, in which the configuration energies have arbitrary values at each vertex. It is found that the partition function can be evaluated by straightforward extensions of the method used for the regular ice, F‐ and KDP‐models, provided three sets of conditions are satisfied. These ensure that the two ordered F‐model states are degenerate (in the limit of a large lattice), so we conclude that the application of any staggered field which breaks this degeneracy also renders the problem insoluble by the present methods.The partition function for these ordered states is obtained explicitly and found to be given quite simply as a product of certain parameters associated with each vertex. Finally some conjectures are made concerning the spontaneous staggered polarization.

THE METEOROLOGICAL ASPECTS OF ICE COVER ON THE GREAT LAKES*

Abstract The formation and break-up of ice on the Great Lakes as observed by regular ice reconnaissance flights conducted by the Meteorological Service of Canada is discussed in terms of the meteorological parameters involved. Ice cover on the individual lakes over the past four years is correlated with the winter temperature regime and an index of the heat stored in each lake using the concept of cumulative degree-days of freezing and thawing. Subjective consideration is also given to the effect of other meteorological factors. As a result of the study, graphs and regression equations have been developed as aids in the prediction of ice cover for the individual lakes. In addition, a comparison of the four years of observations with the 14-yr. period from 1949 to 1963 provides an indication of the average and extreme ice conditions that may be expected for each lake.

船上におけるサバの鮮度保持に対するクロルテトラサイクリン (CTC) 水氷浸漬の効果およびCTCの残存量

Mackerels were placed immediately after being angled in fish hold which contained regular ice and chlortetracycline (CTC)-containing sea water and kept for 6 to 7 days. Freshness and CTC-residue were estimated after landing. Further, a storage experiment at 3-7°C. was carried out in a store room of ice plant. When mackerels were held in about 3 ppm CTC-sea water, the CTC residues in the muscle and the skin were found only 0.05ppm and 0.8ppm, respectively. When held in about 6ppm CTC-sea water, the residues in the muscle and the skin were found 0.09ppm and 1.25ppm, respectively. The distribution pattern of CTC in the muscle showed a sharp decrease in the residue within a 5-mm depth, and no CTC were found in the muscle deeper than 9mm. When mackerels were stored at 3-7°C. after landing, the storage life of both the CTC-treated groups was 7 days as compared with 5 days for the control group. It is of interest that the formation of histamine in the muscle during the storage was greatly inhibited when the fish were dip-treated aboard ship.

The Soviet Expedition to the Central Arctic, 1954

Contains account based on published Russian material. An historical outline of expeditions to the central Arctic between 1937 and 1950 is given. The 1954 expedition, undertaken by the Soviet government and directed by V.F. Burkhanov, consisted of two drift stations (central Arctic station directed by A.F. Treshnikov, eastern Arctic by E.I. Tolstikov), "The High Latitudes Air Expedition" (under M.E. Ostrekin), and regular meteorological and ice observation flights of "flying laboratories" along the edge of the expedition area. Expedition started in Mar. 1954. Establishment on the ice pack of drift stations North Pole-3 and North Pole-4, their living conditions and equipment are described, with illustrations. The air expedition made about 12 landings in the North Pole region and completed its work in July 1954. Little is known of the meteorological flights. Personnel connected with the expedition are listed. An outline of scientific results in oceanography and hydrography (with description of the Lomonosov Range and other topographic features of the Arctic Basin floor), distribution and drift of ice, meteorology, and terrestrial magnetism is given.