Carbamide
and monoamide derivatives are very promising molecules
to achieve U(VI) and Pu(IV) extraction and separation from spent nuclear
fuels through solvent extraction. Herein, coordination structures
of U(VI) and Pu(IV) complexes with carbamide derivatives were characterized
using X-ray crystallography as well as infrared, UV–visible,
and EXAFS spectroscopies. Coordination structures are compared to
those obtained for monoamide derivatives in order to better understand
the role of coordination chemistry in extraction properties. Single
crystals were first synthesized with a short alkyl chain carbamide
analog. Carbamide complexation in the solid state is found analogous
to that in the monoamide. In organic solution, upon solvent extraction
from nitric acid aqueous solution, it is shown that both amide derivatives
can bind in the inner and outer coordination spheres of uranium(VI)
and plutonium(IV). The amount of outer sphere coordination complexes
increases with the amount of nitric acid. With uranium(VI), at a nitric
acid concentration up to 5 mol·L–1, amide derivatives
operate predominantly in the inner coordination sphere. In contrast,
Pu(IV) coordination geometry is much more sensitive toward acid concentration
or ligand structure than U(VI). Pu(IV) changes from inner sphere complexation
at 0.5 mol·L–1 HNO3 to mostly outer
sphere complexation at 4 mol·L–1. The proportion
of outer-sphere complexes is strongly influenced by the ligand structure.
Higher Pu(IV) extraction is found to be correlated with the amount
of Pu(IV) outer sphere species. Secondary interactions in the outer
sphere coordination shell appear to be of primary importance for plutonium
extraction.
In this paper, a parametric study is conducted to optimize a business jet using supersonic bi-directional (SBiDir) flying wing (FW)aiming at achieving high aerodynamic efficiency and low sonic boom. The SBiDir-FW concept has a symmetric planform about both longitudinal and span axes, allowing the plane to achieve high efficiency at both supersonic and subsonic by rotating by 90 o in flight. With this parametric study, the L/Dp achieves 15 at M=1.6, 16 at M=2.0, whereas the sonic boom remains smooth without N-wave. The smooth peak over pressure value is 0.3 psf at M=1.6, 0.4 psf at M=2.0. It indicates that the conventional N-wave could be replaced by a strong acoustic wave, which generates a much less impulsive force and hence noise. The supersonic aspect ratio of the present configuration is 0.33 and the subsonic aspect ratio is 33, which ensures high performance at both supersonic and subsonic. The study shows that the sharp and long nose configuration with ultra-slender body is favorable to both high aerodynamic efficiency and low sonic boom. The numerical results demonstrate that the SbiDir-FW could be a very promising concept for supersonic flight. Further improvement can still be made by using systematic automated design optimization.
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