U-phase

Depending on the data available, Eqs (6.17)-(6.23) reproduce experimental pressure effects with considerable accuracy in many cases. In particular, Eq. (6.18) can be used to confirm entropy data derived using more conventional techniques and can also provide data for metastable allotropes. Ti again provides a leading example, as pressure experiments revealed that the u -phase, previously only detected as a metastable product on quenching certain Ti alloys, could be stabilised under pressure (Fig. 6.14). Extrapolation of the P/w transus line yields the metastable allotropic transformation temperature at which the / -phase would transform to w in the absence of the a-phase, while die slope of the transus lines can be used to extract a value for the relevant entropy via Eq. (6.18). 

Radiochemical analysis of meta-studtite from an SNF test indicated that 237Np was associated with the U6+ peroxide (Table 3). Plutonium, Cm, and Am were found to be in lower concentration in the secondary U phases however, 5-6% of the available Pu and Am, based on reactor code estimates, was co-precipitated with the U phase. The radiochemical data for the collected alteration products from the SNF samples (Table 3) are presented as pg-analyte per g U for comparison to the reactor inventory code calculation for 30MW/d burn-up fuel at 20 y (extracted from Guenther et al. 1988). 

Zhao Ewing (2000) examined altered uraninite from the Colorado Plateau with quantitative electron microprobe analysis in order to determine the fate of trace elements, including Pb, Ca, Si, Th, Zr, and REE, during corrosion under oxidizing conditions. The alteration phases identified included schoepite, calciouranoite, uranophane, fourmarierite, a Fe-rich U phase, and coffinite. The primary uraninites and alteration phases generally had low trace element contents. The electron microprobe analyses indicated that the trace elements preferentially entered the secondary U phases. Alteration caused the loss of U, Pb, and Zr, and incorporation of Si, Ti, Ca, and P into U phases. 

Table 3.4 Air-Hexadecane, Air-Water, and Hexadecane-Water Equilibrium Partitioning of Hexane, Benzene, Diethylether, and Ethanol Free Energies, Enthalpies, and Entropies of Transfer, as well as Partition Constants Expressed on a Molar Base (i.e., mol U phase 1/mol L/ phase 2)...

Figure 11-14. a) Phase boundary b, reflecting the miscibility gap in the system A-B-C, plotted in terms of = f u ) (phase diagram of the third kind), b) Possible reaction paths crossing the phase boundary b of Figure ll-14a, in analogy to Figure ll-12b. 

Chrisochoou, A. Schaber, K. Bolz, U. Phase Equilibria for Enzyme-Catalyzed Reactions in Supercritical Carbon Dioxide. Fluid Phase Equilib. 1995,108, 1-14. 

Brandenburg, K., Koch, M.H.J., Seydel, U. Phase diagram of lipid A from Salmonella minnesota and Escherichia coll rough mutant lipopolysaccharide. J Struct Biol 105 (1990) 11-21. 

For steady two-phase flow of the M and U phases at 30.0 C the same behavior with ganglia of the same size can be attained with a flow rate of 3.6 ft/day. Ca is comparable at 9.5 x 10". Although no mobile ganglia larger than twenty BD were observed in anx of our experiments, their existence in the range of Ca = 10" - 10 cannot be ruled out due to the relatively small overall size of the flow cell. 

Uranium(VI) readily precipitates in the presence of phosphate to form a number of sparingly soluble U-phosphate phases (U phases, such as saleeite, meta-autunite, and autunite) and also is removed by sorption and co-precipitation in apatite. Several studies have shown that hydroxyapatite is extremely effective at removing heavy metals, uranium, and other radionuclides from solution (Gauglitz et al., 1992 Arey and Seaman, 1999). 

Riiner, U., Phase Behavior of Hydrogenated Fats. II. Polymorphic Transitions of Hydrogenated Sunflower Seed Oil and Solutions, Lebensm. Wiss. Technol. 4 113-117 (1971),... 

Fig. 7.2 Fluorite UOj structure contains eightfold coordinated U atoms (grey spheres) and fourfold coordinated O atoms (black spheres)-, the cell unit length a=b = c = 5.47A. Uranium cations can have an oxidation state greater than U +, as a result of the removal of two electrons from the 5/ orbital, to become The UO system can be used as a model for oxidation/reduction reactions since it is an intermediate between the uranium metal (U ) phase and the most oxidized uranium phase (UO )...

In this way, u changes slowly when Vref(x) is large. Thus, the u phase space associated with the barrier region is very small as desired. Sampling in u phase space without a barrier is rigorously correct because no time is spent in the barrier region as defined in the x phase space The authors encourage the reader to carefully consider the different mathematics required by REPSWA and other methods as well as the different conceptual description. 

We consider transfer from the U phase to the L phase as leading to a positive flux. 

Leaver MS, Olsson U, Wennerstrom H, Strey R, Wurz U. Phase behavior and structure in a nonionic surfactant-oil-water mixture. J Chem Soc Faraday Trans 1995 91 4269-4274. 

Figure 2. Temperature dependence of the basis vector length, d (see Figure 5), of the fully hydrated H u phase of DOPE is shown by the open squares. The line is the fit to the data under the assumption of a linear dependence of the monolayer thickness with temperature. (Reproduced from reference 24.

Figure 4.8 Part of the nickel-copper (Ni u) phase diagram not to scale...

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