Amount Of Unfrozen Water Research Articles

Determining the amount of unfrozen water in a foam phenol plastic

Determining the amount of unfrozen water in a foam phenol plastic

Calorimetric study of water in muscle tissue

Differential scanning calorimetry has been used to investigate the state of water in intact single muscle fibers of the giant barnacle, Balanus nubilus. The shapes of the melting curves suggest the presence of three types of water: unfrozen (or bound), free (or bulk) and intermediate water. The amount of unfrozen water per g protein was constant within experimental error. An increase in water content changed almost exclusively the amounts of free water. The amount of intermediate water varies only slightly with the fiber water content.

Unfrozen water as a function of clay microstructure

A previous study of microstructural changes in freezing clay suggested that a “dispersed” freshwater clay should have a higher percentage of unfrozen water than a (leached) marine clay with similar mineralogical and granulometrical compositions. This report describes an investigation where two such clays were actually compared concerning their contents of unfrozen water. The results confirmed the hypothesis. Thus, the influence of clay microstructure on the amount of unfrozen water was clearly shown. The degree of particle aggregation and the density of the particle aggregates are the main microstructural parameters.

Freezing of Water in Red-Osier Dogwood Stems in Relation to Cold Hardiness

Studies of stem water in red-osier dogwood (Cornus stolonifera Michx.) using nuclear magnetic resonance spectroscopy indicated that most freezing occurs at temperatures above -30 C in cold-hardy and tender stems. Hardy and tender stems had about the same amount of unfrozen water at -40 C (0.28 gram of water per gram dry weight). When hardy stems were slowly cooled below -20 C, the temperature below which little additional freezing occurs, they survived direct immersion in liquid N(2) (-196 C). Fully hardy samples not slowly precooled to at least -15 C did not survive direct immersion in liquid N(2). The results support the hypothesis that cooling rate is an unimportant factor in tissue survival at and below temperatures where there is little freezable water.

Salt and Water Movement in Unsaturated Frozen Soil

AbstractSalt and water movement was measured in unsaturated frozen soil columns incubated under a thermal gradient for 3, 6, or 9 weeks. Both water and salt moved from the warmer to cooler areas in the soil, creating a twofold concentration difference over a 24‐cm distance. Movement of CaCl2, LiI, and K2SO4 was studied in detail. Cation exchange reactions and salt solubilities at high concentrations affected the movement. Although the results suggested that mass flow of dissolved salts in a liquid film of water was the principal transfer mechanism, both vapor and salt diffusion were sometimes significant. Thermal diffusion and salt sieving did not appear to be important.Since the vapor pressure of ice controls the water potential in frozen soil, the amount of unfrozen water and matric suction could be calculated from a water release curve and data from ice suspensions in salt solutions. These results led to the conclusion that mass flow in the liquid phase is described by Darcy's law. Thus, salt flow as well as net water transfer can probably be predicted in unsaturated frozen soil using information available from unfrozen systems.

Soil–Ice Behavior in a Model Retaining Structure

Experimental creep data on model cylindrical retaining structures formed from two frozen soils, saturated Ottawa sand and Ontonagon (Sault Ste. Marie) clay, are presented. The sand–ice behavior in the model barrier is analyzed using a constitutive relationship which includes the state of stress, state of strain, time, and temperature. Displacement rates at the inner wall surface calculated according to the creep relationship agree with measured rates for properly chosen values of a parameter which modifies the contribution of the deviatoric stress component to the creep rate.The axial force observed at the sample ends provided information as to the soil–ice behavior during primary and secondary creep. For the sand–ice material this axial force did not reach its final value until steady-state creep was approximated. This indicates that Poisson's ratio may change depending on the stage or development of the creep deformations. This behavior was not observed for the frozen clay. The stress – strain – time behavior for the two soils differed considerably due to the greater amounts of unfrozen water in the frozen clay (about 50 %) as compared with the saturated Ottawa sand (little or none).

Viscosity of Water in Clay Systems

AbstractA method was devised for obtaining the activation energy for the viscous flow of a fluid through a porous medium and the method was applied to the flow of water through samples of Na-bentonite. The resulting activation energies were generally higher than the activation energy for the flow of pure water. The activation energy depended on the length of time the water was in contact with the clay and also on the particular sample. For any given sample, the water flow rate was negatively correlated with the activation energy, in accordance with theory.To help interpret these results, data are presented on the tension of water in Na-bentonite suspensions at different intervals of time after stirring. The water tension was near zero immediately after stirring but increased gradually with time. Simultaneously the suspension gelled. Data also are presented on the specific volumes of water, the activation energies for ion movement, the diffusion coefficients of chloride salts and the unfrozen water at -5°C in Li-, Na- and K-bentonite. The activation energies for ion movement and the amounts of unfrozen water were positively correlated with the specific volumes of the water, whereas the diffusion coefficients of the chloride salts were negatively correlated with the specific volumes of the water. In each clay the specific volume of the water and the activation energy for ion movement were higher than those in normal water.It is concluded that a water structure, which varies in extent with particle arrangement and the adsorbed cationic species, exists at the surface of clay particles. This structure bestows a high viscosity to the adsorbed water.