As part of an experimental validation of a nuclear forensics methodology for Pu source reactor-type discrimination, destructive analysis has been performed on two irradiated UO2 pellets with different irradiation histories. Analysis has focused on measuring key Sm fission product isotope ratios used in a previously published maximum likelihood methodology to determine the most likely irradiation history of the pellets. A total of 21 Sm isotope ratios were measured within the irradiated pellets, and generally agreed within 20% of the irradiations as simulated using the Monte Carlo Radiation Transport and material depletion code, MCNP6. Results indicate the chosen approach can accurately measure the isotope ratios within 5% experimental error.
The structure of methyl (6R)‐6‐(3′β‐acetoxy‐5′‐androsten‐17′β‐yl)‐2‐phenyl‐5,6‐dihydro‐4H‐[1,3]oxazine, C31H41NO3, synthesized from an azidopregnene derivative, is reported. The dihydro‐1,3‐oxazine ring is connected in the β position to the sterane skeleton at C‐17′. An R configuration was found at C‐6. 相似文献
Mixing aqueous dispersions of thiocyanate ion coated small (< 3.5 nm diameter) gold nanoparticles and EDTA covered larger (> 22 nm diameter) silver nanoparticles, results in the formation of robust gold encased silver nanoparticles; in contrast to using larger (> 11 nm diameter) gold nanoparticles which forms chained structures. 相似文献
We compute the adjoint generator for the infinitesimal generator A of a C0-semigroup. The operator A is associated with a particular scalar nonatomic neutral equation. 相似文献
Multiwalled carbon nanotubes have been functionalized using n-butyllithium and then covalently bonded to a chlorinated polypropylene. The following addition of the polymer-grafted nanotubes to the chlorinated polypropylene polymer matrix resulted in significant increase of mechanical properties. As nanotube content is increased to 0.6 vol %, Young's Modulus increased by a factor of 3, while both the tensile strength and the toughness increased by factors of 3.8 and 4, respectively. This covalent functionalization enables us to get an efficient dispersion and excellent interfacial stress transfer, potentially leading to new ultra-strong polymer composite materials. 相似文献
Let X and Y be affine nonsingular real algebraic varieties.A general problem in real algebraic geometry is to try to decidewhen a continuous map f: XY can be approximated by regularmaps in the space of c0 mappings from X to Y, equipped withthe c0 topology. This paper solves this problem when X is theconnected component containing the origin of the real part ofa complex Abelian variety and Y is the standard 2-dimensionalsphere. 相似文献
The octakis(DMSO) (DMSO = dimethylsulfoxide) neodymium(III), samarium(III), gadolinium(III), dysprosium(III), erbium(III), and lutetium(III) iodides crystallize in the monoclinic space group P21/n (No. 14) with Z = 4, while the octakis(DMSO) iodides of the larger lanthanum(III), cerium(III), and praseodymium(III) ions crystallize in the orthorhombic space group Pbca (No. 61), Z = 8. In all [Ln(OS(Me2)8]I3 compounds the lanthanoid(III) ions coordinate eight DMSO oxygen atoms in a distorted square antiprism. Up to three of the DMSO ligands were found to be disordered and were described by two alternative configurations related by a twist around the metal-oxygen (Ln-O) bond. To resolve the atomic positions and achieve reliable Ln-O bond distances, complete semirigid DMSO molecules with restrained geometry and partial occupancy were refined for the alternative sites. This disorder model was also applied on previously collected data for the monoclinic octakis(DMSO)yttrium(III) iodide. At ambient temperature, the eight Ln-O bond distances are distributed over a range of about 0.1 A. The average value increases from Ln-O 2.30, 2.34, 2.34, 2.36, 2.38, 2.40 to 2.43 A (Ln = Lu, Er, Y, Dy, Gd, Sm, and Nd) for the monoclinic [Ln(OSMe2)8]I3 structures, and from 2.44, 2.47 to 2.49 A (Ln = Pr, Ce, and La) for the orthorhombic structures, respectively. The average of the La-O and Nd-O bond distances remained unchanged at 100 K, 2.49 and 2.43 A, respectively. Despite longer bond distances and larger Ln-O-S angles, the cell volumes are smaller for the orthorhombic structures (Ln = Pr, Ce, and La) than for the monoclinic structure with Ln = Nd, showing a more efficient packing arrangement. Raman and IR absorption spectra for the [Ln(OS(CH3)2)8]I3 (Ln = La, Ce, Pr, Nd, Gd, Tb, Dy, Er, Lu, and Y) compounds, also deuterated for La and Y, have been recorded and analyzed by means of normal coordinate methods. The force constants for the Ln-O and S-O stretching modes in the complexes increase with decreasing Ln-O bond distance and show increasing polarization of the bonds for the smaller and heavier lanthanoid(III) ions. 相似文献