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this phenomenon has nothing to do with the rheological complexities of the ambient liquids, and its interpretation must be sought in the different behavior of bubbles and drops in liquids. The larger the bubble is, the larger the contact area between the concave face of the leading and the convex face of the trailing bubble cap. Thus, the area of the film to be drained increases with the increasing basal diameter of the bubble. On the other hand, drops in the region of diameters between 0.004 and 0.007 m remain essentially spherical. CONCLUSIONSThe elasticity of polymer solutions has a tendency to increase both the collision and the coalescence times of gas bubbles and liquid drops. Thus, polymer additives with strong elastic component may reduce the overall coalescence rate considerably.Greek Letters a y = shearrate o = angular velocity = material parameter, Equation (3) = material parameter, Equation ( 3 ) = basal diameter of a bubble/drop = axial thrust between the cone and the plate of the R18 rheogoniometer = acceleration due to gravity = material parameter, Equation (3) = material parameter, Equation (3) = radius of the cone and plate setup = torque between the cone and the plate of the R18 rheogoniometer = initial separation of bubbles/drops = complementary apex angle between the cone and the plate in the R18 rheogoniometer 7 = apparent viscosity p = density k u1 = characteristic time of a viscoelastic liquid = primary normal stress difference A three-phase fluidized bed consists of solid phase particles fluidized by a gas and liquid flow. Although many Begovich. schemes for contacting the three phases are possible, a common method is to fluidize the solid phase by the upward concurrent flow of gas and liquid. The liquid forms Correspondence concerning this note should be addressed to J. M.

Small, ceramic urania spheres can be prepared for use as nuclear fuel by internal chemical gelation of uranyl nitrate solution droplets. Acid-deficient uranyl nitrate solutions up to 3.4 M in uranium with N03'/U mole ratios of 1.5 to 1.7 are prepared by dissolution of U308 or U03. Decomposition of hexamethylenetetramine dissolved in the uranyl nitrate solution releases ammonia to precipitate hydrated U03. Previously established flowsheet conditions have been improved and modified at ORNL and have been applied to prepare dense U02 spheres with average diameters of 1200, 300, and 30 pm. The 1200and 300-^m U02 spheres were prepared by gelation in trichloroethylene at 50 to 65 °C; 2-ethyl-1-hexanol was used as the gelation medium to prepare 30-;um U02 spheres.

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