Allen R. Tice

Partial glass formation: a novel mechanism of insect cryoprotection

Abstract The gall fly larva Eurosta solidaginis utilizes a freeze tolerant strategy in overwintering. As seasons progress from autumn to winter, the third instar stage of the fly increases its production of polyols, thereby decreasing the equilibrium freezing point of the aqueous compartments. Proton NMR studies of the intact larvae and of hemolymph-like solutions indicate an increase in proton mobility in the −25 to −45 °C range. This increase in apparent mobility is due to a glass transition as confirmed by DSC studies. This study identifies for the first time that a freeze-tolerant insect enters a partial amorphous (glassy) state following freezing encounters. A novel strategy of cryoprotection is described that is of relevance in understanding the overall mechanism of animal cell/tissue tolerance to freezing.

Water vapor adsorption by sodium montmorillonite at −5°C

Abstract A large amount of interest has recently been expressed pertaining to the quantity of physically adsorbed water by the Martian regolith. Thermodynamic calculations based on experimentally determined adsorption and desorption isotherms and extrapolated to subzero temperatures indicate that physical adsorption of more than one or two monomolecular layers is highly unlikely under Martian conditions. Any additional water would find ice to be the state of lowest energy and therefore the most stable form. To test the validity of the thermodynamic calculations we have measured adsorption and desorption isotherms of sodium montmorillonite at −5°C. To a first approximation it was found to be valid.

Transport of water in frozen soil: I: Experimental determination of soil-water diffusivity under isothermal conditions

Abstract A new experimental method for measuring the soil-water diffusivity of frozen soil under isothermal conditions is introduced. The theoretical justification of the method is presented and the feasibility of the method is demonstrated by experiments conducted using marine deposited clay. The measured values of the soil-water diffusivity are found comparable to reported experimental data.

Transport of water in frozen soil II. Effects of ice on the transport of water under isothermal conditions

Abstract Effects of ice on the transport of water in frozen soil were investigated under isothermal conditions. Based on the experimental results obtained using a marine-deposited clay at −1.0°C, the presence of ice is shown to significantly affect the transport of water under certain circumstances. A theoretical analysis of the experimental results and a discussion of a possible mechanism for water transport in frozen soil are presented.

Unfrozen water contents of submarine permafrost determined by nuclear magnetic resonance

Abstract Prior work resulted in the development of techniques to measure the unfrozen water contents in frozen soils by nuclear magnetic resonance (NMR). It has been demonstrated that NMR is a promising new method for the determination of phase composition (the measurement of unfrozen water content as a function of temperature) which circumvents many of the limitations inherent in the adiabatic and isothermal calorimetric techniques. The NMR technique makes it possible, in a non-destructive, non-intrusive way, to explore hysteresis by determining both cooling and warming curves. Corrections are made for dissolved paramagnetic impurities which have the effect of increasing the signal intensity at decreasing temperatures. The results demonstrate that NMR techniques can be effectively utilized both at and below the melting point of ice in frozen soils and that accurate melting points (freezing point depressions) can be determined.

Transport of water in frozen soil: III. Experiments on the effects of ice content

Abstract Effects of ice content on the transport of water in frozen soil are studied experimentally and theoretically under isothermal conditions. A physical law, that the flux of water in unsaturated frozen soil is proportional to the gradient of total water content, is proposed. Theoretical justification is made by the use of the two-phase flow theory. The experimental results are shown to support the proposed physical law. The results of this study are presented in two parts. The experimental aspects of the study are presented in this paper and the second paper contains the theoretical aspects of the study.

Transport of water due to a temperature gradient in unsaturated frozen clay

Abstract As reported experimental data indicate, the net flux of water f in a fine-grained soil column was assumed to be given as: f=−D 1 (w,T) αw αx −ρD 2 (w,T) αT αx where ϱ is the dry density, T is the temperature (°C), w is the content of water in all phases, x is the coordinate, and empirical functions D1 and D2 are the properties of a given soil. Under this assumption a new experimental method was introduced to determine D2 of a soil with known D1. The D2 of Morin clay was determined as a function of w at several temperatures ranging between − 1.0 and 1.0°C. A common feature found is that D2 increases with increasing w, attains its maximum near or not far from a point where w is equal to the equilibrium unfrozen water content, and then decrease when T is negative. However, D2 increases with increasing w up to about 14%, and then remains more or less constant as w increases when T is positive. Because of this behavior of D2 a sudden change (or discontinuity) of D2 occurs near a point where T = 0°C when w is greater than 14%. The validity of the assumed functional description of the flux f is discussed based on some recent results of mathematical analysis on degenerate quasi-linear equations of parabolic type.

Transport of water in frozen soil IV. Analysis of experimental results on the effects of ice content

Abstract Effects of ice content on the transport of water in frozen soil are studied experimentally and theoretically under isothermal conditions. A physical law, that the flux of water in unsaturated frozen soil is proportional to the gradient of total water content is proposed. Theoretical justification is made by the use of the two-phase flow theory. The experimental results are shown to support the proposed physical law. The results of this study are presented in two parts and this is the second paper describing the theoretical aspects of the study.

The effects of magnetic particles on the unfrozen water content of frozen soils determined by nuclear magnetic resonance

Small ferromagnetic particles in soils locally change the magnetic field of a nuclear magnetic resonance (NMR) analyzer. This causes a decrease in the NMR signal intensity when NMR is being used to measure unfrozen water contents in partially frozen soils or total water contents in thawed soils. We mixed Tuto clay, a soil containing no magnetic particles, with various small amounts of pure powdered magnetite, and determined the NMR signal intensity while the samples were both thawed and partially frozen. Then we derived an equation that correlates the thawed sample signal intensity with the weight percent of powdered magnetite added. The unfrozen water content of the partially frozen samples could be determined accurately for samples containing up to 0.2 to 0.3% magnetite. Several methods for demagnetizing soils containing large amounts of magnetic particles were tried, with the most effective found to be stirring a slurry of the soil over a powerful permanent magnet. Accurate unfrozen water contents could be determined for all the partially frozen samples if some form of demagnetizing procedure was used on those samples containing the most magnetic particles.

THE WATER-ICE PHASE COMPOSITION OF CLAY/WATER SYSTEMS. 1. THE KAOLINITE/WATER SYSTEM

Previous studies indicated that when water-ice phase composition curves are normalized to unit surface area, the unfrozen water content values at given temperatures for the kaolinite/water system are higher than those of other soils and soil constitutents. The water-ice phase composition curve for this system has been redetermined using an improved isothermal calorimeter and the earlier curve confirmed. For most soils, water-ice phase composition curves are well represented by a simple power curve. In contrast, the layer-lattice silicate/water systems so far investigated behave differently; segments of two power curves are required to fit the data. Addition of Polyox (polyethylene oxide) to the kaolinite/water system had little effect on the unfrozen water content when the temperture ranged from 0 to 1.7 degrees below freezing but diminished the unfrozen water content significantly at values of 1.7 or more below freezing. Values of the unfrozen water content per kaolinite/water systems are more than twice as large as those for the two representative montmorillonite/water systems investigated. /AUTHOR/