diffusion remains below 10 −4 nm 2 s −1. In the liquid state at 3270 K, the rates of U and O diffusion are of similar magnitude (3.7 versus 9.3 nm 2 s −1). Manara et al. measured a melting slope (dT m /dP) that is a factor 1.5 to 2 steeper than expected from the recommended volume change on melting and enthalpy of fusion values (11, 16). The rapid O exchange in these MD models results in a relatively low enthalpy of fusion, consistent with a relatively steep melting slope. Using pressure , an 8-coordinated UO 2 melt can be simulated at a number density of 0.074 Å −3. The 8-coordinated melt has U and O diffusion rates slower by a factor of 3 (1.2 and 3.8 nm 2 s −1) than the low-coordinated melt, demonstrating the strong effect of local structure on the physical properties of this melt. The Andrade theory, for example, is often used to predict melt viscosity but assumes that the melt structure closely resembles that of the solid (17, 18). Portions of the hot solid and liquid UO 2 MD simulations illustrate the large oxygen disorder above the lambda transition and the different UO 6,7 coordination species that predominate in the melt (Fig. 3C). The structure and optimized interatomic potentials for UO 2 allow for accurate atomistic multiscale modeling. The x-ray data are important as an end-member benchmark for models of multicomponent systems, including corium melts and high-level waste glasses (11). (6212), 987-991. 346 Science , this issue p. 987 Science mice could prove valuable for preliminary screens of candidate therapeutics and vaccines. virus was associated with distinct genetic profiles in inflammation, blood coagulation, and vascular function. This panel of series of painstaking experiments performed under stringent biosafety conditions. Resistance and susceptibility to Ebola tested the effects of Ebola virus in mice with defined genetic backgrounds in a et al. as those of humans. Rasmussen Apart from monkeys, there are no animal models available that show the same symptoms of Ebola virus infection Variety of Ebola symptoms in mice ARTICLE TOOLS

Actinides / Lanthanides / TALSPEAK / NPEX / Separation / Pu / NpSummary. Bench-scale studies to determine the extraction behavior of Pu, Np, Am and lanthanides with the organophosphorus extractants TBP, CMPO and HDEHP have been carried out. Based on the results obtained using actual spent nuclear fuel solutions, enhancements to the NPEX, TRUEX and TAL-SPEAK processes have been successful. In NPEX, > 99.94% of both Np and Pu were separated from the fission products. In TRUEX, essentially complete recovery of the actinides (An) and the lanthanides (Ln) was achieved. In TALSPEAK, the complete separation of Pu, Np and Am from the lanthanides was demonstrated several times under various process conditions. The recovery of transuranics (TRU), including Am and Cm, is nearly 100% (below detection limit in the Ln stream), while the total recovery of Ln in the product stream exceeded 99.97%.

An aerodynamic levitator with carbon dioxide laser beam heating was integrated with a hermetically sealed controlled atmosphere chamber and sample handling mechanism. The system enabled containment of radioactive samples and control of the process atmosphere chemistry. The chamber was typically operated at a pressure of approximately 0.9 bars to ensure containment of the materials being processed. Samples 2.5-3 mm in diameter were levitated in flowing gas to achieve containerless conditions. Levitated samples were heated to temperatures of up to 3500 °C with a partially focused carbon dioxide laser beam. Sample temperature was measured using an optical pyrometer. The sample environment was integrated with a high energy (100 keV) x-ray synchrotron beamline to enable in situ structure measurements to be made on levitated samples as they were heated, melted, and supercooled. The system was controlled from outside the x-ray beamline hutch by using a LabVIEW program. Measurements have been made on hot solid and molten uranium dioxide and binary uranium dioxide-zirconium dioxide compositions.

Cellulose acetate (CA) can be converted to cellulose II through a deacetylation process using ethanolic NaOH solution. Infrared spectroscopy was used to observe the degree of acetylation by comparing the absorption intensities of CO and C−O stretches. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) analysis, which only measures a few microns into the fiber diameter, was compared with FTIR, which measures the whole fiber cross-section. Steady deacetylation of the whole fiber over 180 min was observed with FTIR to eventual complete deacetylation. In comparison, ATR-FTIR shows deacetylation occurring more rapidly to complete deacetylation after 90 min, indicating rapid deacetylation of the CA fiber periphery. Data were fitted to a pseudo-second order kinetic model, with high correlation (R 2 > 0.99), and it was observed that the deacetylation rate (k 2 ) observed with ATR-FTIR (−0.634 min −1 ) was twice as rapid as the deacetylation rate observed with FTIR (−0.315 min −1 ). IR observations were in agreement with the analysis of fiber cross-sections by confocal microscopy, where it was observed that changes in fiber morphology occurred with treatment time and progressive hydrolysis of cellulose acetate to cellulose II. A differential fiber chemical composition was created within the CA fiber cross-section; after 5 min, the outer regions of the fiber cross-section are hydrolyzed to cellulose II and this hydrolysis increases heterogeneously with time to complete hydrolysis after 180 min and conversion to cellulose II. These results indicate the potential to produce fibers with a differential periphery/core structure, which can be accurately designed according to the relative degrees of cellulose II/CA required for specific applications by varying the treatment time in application of this model.

At present, most 99 Mo is produced in research, test, or isotope production reactors by irradiation of highly enriched uranium targets. To achieve the denser form of uranium needed for switching from high to low enriched uranium (LEU), targets in the form of a metal foil (~125-150 µm thick) are being developed. The LEU High Density Target Project successfully demonstrated several iterations of an LEU-fission-based Mo-99 technology that has the potential to provide the world's supply of Mo-99, should major producers choose to utilize the technology. Over 50 annular high density targets have been successfully tested, and the assembly and disassembly of targets have been improved and optimized. Two target front-end processes (acidic and electrochemical) have been scaled up and demonstrated to allow for the high-density target technology to mate up to the existing producer technology for target processing. In the event that a new target processing line is started, the chemical processing of the targets is greatly simplified. Extensive modeling and safety analysis has been conducted, and the target has been qualified to be inserted into the High Flux Isotope Reactor, which is considered above and beyond the requirements for the typical use of this target due to high fluence and irradiation duration. FIGURE 1.3 (A) Target Insertion Rig and (B) Target Insertion Rig with Target Showing Cooling Channel on Inside of Target. Up to Three Targets Can Be Placed on Each Rig.