We demonstrate that stable nonlinear localized modes can exist not only at a light-mass isotopic impurity, but also at a heavy-mass impurity, due to an interplay between discreteness and nonlinearity. This is in sharp contrast to the theory of linear lattice vibrations that an impurity mode is possible only at a light-mass defect. We determine the structure of the nonlinear impurity modes analy...

We describe the optical resonant manipulation of a single magnetic impurity in a self-assembled quantum dot. We show that using the resonant pumping one can address and manipulate selectively individual spin states of a magnetic impurity. The mechanisms of resonant optical polarization of a single impurity in a quantum dot involve anisotropic exchange interactions and are different than those i...

This paper gives an overview of the research activities at TEXTOR on impurity production, impurity transport through the plasma, and then deposition. First, laboratory experiments on chemical erosion by hydrogen and oxygen and radiation-enhanced sublimation are described, followed by the main part, which concentrates on the TEXTOR data of impurity release, impurity transport, and redeposition. ...

We study the properties of a quantum impurity embedded in a superconducting host of a d-wave symmetry. The superconductor is described by the extended negative U Hubbard model while the impurity introduces a repulsive interaction to the system around the central site. We discuss the influence of this repulsion on the local properties (density of states, electron pairing and spontaneous current ...

Impurity transport coefficients and the penetration efficiencies of intrinsic and injected impurities through the separatrix of diverted Al-cator C-Mod discharges have been measured using x-ray and VUV spec-troscopic diagnostics. The dominant low Z intrinsic impurity in C-Mod is carbon which is found to be present in concentrations of less than 0.5%. Molybdenum, from the plasma facing component...

We investigate the optical conductivity of a Hubbard ring in presence of an impurity by means of exact diagonalization using the Lanczos algorithm. We concentrate thereby on the first excited, open shell state, i.e. on twisted boundary conditions. In the metallic phase a substantial part of the spectral weight lies in the Drude peak, σ(ω) = Dcδ(ω)+σreg . In the non-interacting system, the Drude...

in this research, the high-energy planetary mill was employed to produce nanocrystalline ti-50al(γ)(at%) powders. initial powders were mechanically alloyed in 99.9999% and 90% purities of argon and also air atmosphere with alloying times up to 50h. the effect of impurity of argon atmosphere on the microstructure and the rate of phase transformation of ti-50al were investigated during mechanical...

We consider a version of the symmetric Anderson impurity model (compactified) which has a non-Fermi liquid weak coupling regime. We find that in the Majorana fermion representation the perturbation theory can be conveniently developed in terms of Pfaffian determinants and we use this formalism to calculate the impurity free energy, self energies, and vertex functions. We also derive expressions...

Six impurities in pantoprazole sodium bulk drug substance were detected by a simple high performance liquid chromatographic method (HPLC) whose area percentage ranged from approximately 0.05 to 0.34%. Liquid chromatography-mass spectrometry (LC-MS) was performed to identify the molecular weight of the impurities. A thorough study was undertaken to characterize these impurities. These impurities...

Identification and control of impurities for drug substances is a critical task in pharmaceutical process development for quality and safety. The most commonly used analytical technique for impurity analysis in drug substances and drug products is undoubtedly a chromatographic method, namely high performance liquid chromatography (HPLC). Impurity profiling is typically performed by HPLC and imp...