[1] An experiment is described in which a groundwater bacterium, Sphingomonas sp., influenced the dynamics of unsaturated flow at a fracture intersection. A washed cell suspension increased by three-fold the length of time that water pooled at the fracture intersection. On the other hand, the addition of growth substrates resulted in cell growth and the conversion from intermittent to continuous flow behavior at the fracture intersection. The results suggest that microbial properties and processes need to be included with other important variables for understanding unsaturated flow in fractured geomatrices.
Polyphosphazenes are a class of inorganic polymers characterized by the phosphorus nitrogen repeating unit that forms the backbone. The phosphorus is pentavalent and the backbone has alternating single and double bonds. This leaves two coordination sites on the phosphorus free for substituted with a variety of nucleophilic groups. Several hundred polyphosphazene formulations have been reported in the literature. The ease of controlling the type and number of substituents provides a unique opportunity to develop special series of polymers to investigate structure property relationships. In this paper the pure gas permeabilities of a series of substituted bisphenoxyphosphazene polymers is reported. The polymers were exposed to ten different gases and the resulting permeabilities were analyzed using the time lag method. The time lag method enables the permeability to be broken down into its solubility and diffusivity components. Careful examination of the results makes it possible to determine what types of substituent-gas interactions are responsible for the overall permeabilities in the polymers. Some of
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