In this paper, we study a hydrodynamic system describing fluids with viscoelastic properties. After a brief examination of the relations between several models, we shall concentrate on a few analytical issues concerning them. In particular, we establish local existence and global existence (with small initial data) of classical solutions for an Oldroyd system without an artificially postulated damping mechanism.

The conventional definition of spin current is incomplete and unphysical in describing spin transport in systems with spin-orbit coupling. A proper and measurable spin current is established in this study, which fits well into the standard framework of near-equilibrium transport theory and has the desirable property to vanish in insulators with localized orbitals. Experimental implications of our theory are discussed.

Manipulating the Kondo effect by quantum confinement has been achieved by placing magnetic molecules on silicon-supported nanostructures. The Kondo resonance of individual manganese phthalocyanine (MnPc) molecules adsorbed on the top of Pb islands was studied by scanning tunneling spectroscopy. Oscillating Kondo temperatures as a function of film thickness were observed and attributed to the formation of the thickness-dependent quantum-well states in the host Pb islands. The present approach provides a technologically feasible way for single spin manipulation by precise thickness control of thin films.

Plutonium dioxide is of high technological importance in nuclear fuel cycle and is particularly crucial in long-term storage of Pu-based radioactive waste. Using first-principles density-functional theory, in this paper we systematically study the structural, electronic, mechanical, thermodynamic properties, and pressure induced structural transition of PuO 2 . To properly describe the strong correlation in Pu 5f electrons, the local density approximation+U and the generalized gradient approximation+U theoretical formalisms have been employed. We optimize U parameter in calculating the total energy, lattice parameters, and bulk modulus at nonmagnetic, ferromagnetic, and antiferromagnetic configurations for both ground state fluorite structure and high pressure cotunnite structure. Best agreement with experiments is obtained by tuning the effective Hubbard parameter U at around 4 eV within LDA+U approach. After carefully testing the validity of the ground-state calculation, we further investigate the bonding nature, elastic constants, various moduli, Debye temperature, hardness, ideal tensile strength, and phonon dispersion for fluorite PuO 2 . Some thermodynamic properties, e.g., Gibbs free energy, volume thermal expansion, and specific heat, are also calculated. As for cotunnite phase, besides elastic constants, various moduli, and Debye temperature at 0 GPa, we have further presented our calculated electronic, structural, and magnetic properties for PuO 2 under pressure up to 280 GPa. A metallic transition at around 133 GPa and an isostructural transition in pressure range of 75-133 GPa are predicted. Additionally, as an illustration on the valency trend and subsequent effect on the mechanical properties, the calculated results for other actinide metal dioxides (ThO 2 , UO 2 , and NpO 2 ) are also presented.

A physical phenomenon has been found: in a structure of nanometal film with dielectric-medium loading, the surface polaritons excited by a uniformly moving electron bunch can be transformed into Cherenkov radiation with intensity enhancement in the medium. Based on this mechanism, the surface polariton Cherenkov light radiation source is presented and explored in the Letter. The results show that surface polariton Cherenkov light radiation source can generate radiation, from visible light to the ultraviolet frequency regime and the radiation power density can reach or even exceed 10(8) W/cm(2) depending on the beam energy and current density. It is a tunable and miniature light radiation source promising to be integrated on a chip and built into a light radiation source array.