Suprapermafrost Water: Completion Report

OWRR Contract No. 14-31-0001-9010 Grant No. C-4049The work upon which this completion report is based was supported by funds provided by the US Department of the Interior, Office of Water Resources Research as authorized under the Water Resources Research Act of 1964, Public Law 88-379, as amended

Symmetries and Elasticity of Nematic Gels

A nematic liquid-crystal gel is a macroscopically homogeneous elastic medium with the rotational symmetry of a nematic liquid crystal. In this paper, we develop a general approach to the study of these gels that incorporates all underlying symmetries. After reviewing traditional elasticity and clarifying the role of broken rotational symmetries in both the reference space of points in the undistorted medium and the target space into which these points are mapped, we explore the unusual properties of nematic gels from a number of perspectives. We show how symmetries of nematic gels formed via spontaneous symmetry breaking from an isotropic gel enforce soft elastic response characterized by the vanishing of a shear modulus and the vanishing of stress up to a critical value of strain along certain directions. We also study the phase transition from isotropic to nematic gels. In addition to being fully consistent with approaches to nematic gels based on rubber elasticity, our description has the important advantages of being independent of a microscopic model, of emphasizing and clarifying the role of broken symmetries in determining elastic response, and of permitting easy incorporation of spatial variations, thermal fluctuations, and gel heterogeneity, thereby allowing a full statistical-mechanical treatment of these novel materials.Comment: 21 pages, 4 eps figure

Sediment Relations of Selected Alaskan Glacier-fed Streams: Completion Report

The work upon which this report is based was supported by funds provided by the U.S. Department of Interior, Office of Water Resources Research as authorized by the Water Resources Research Act of 1964, Public Law 88-379, as amended

Laboratory Experiments Evaluating the Transport and Fate of DBCP in Hanford Sandy Loam

Soil column, batch adsorption, and batch biodegradatian experiments were conducted to determine the fate of DBCP applied in irrigation water at low concentrations (≈ 3 µg L−1) to unsaturated Hanford sandy loam soil (coarse-loamy, mixed, nonacid, thermic Typic Xerorthents). The objective was to determine the extent that soil might treat DBCP-contaminated groundwater proposed for irrigation of citrus in the Redlands California area. Water applications were performed cyclically to simulate citrus irrigation practices. Volatilization of DBCP to the atmosphere between irrigations was the dominant mechanism controlling its fate once applied to the soil. Soil adsorption was found to retard the transport of DBCP 3 to 5 times when compared with the wetting front movement. Batch biodegradation experiments suggested that DBCP may also be significantly metabolized by subsurface microorganisms. The half-life was estimated to be approximately 7 d. Soil water characteristic curve hysteresis was observed with the soil column experiments and water content distributions calculated from soil water pore pressures required that scanning curves be developed to accurately simulate experimental data