465 research outputs found
Atomic States Entanglement in Carbon Nanotubes
The entanglement of two atoms (ions) doped into a carbon nanotube has been
investigated theoretically. Based on the photon Green function formalism for
quantizing electromagnetic field in the presence of carbon nanotubes,
small-diameter metallic nanotubes are shown to result in a high degree of the
two-qubit atomic entanglement for long times due to the strong atom-field
coupling.Comment: 4 pages, 2 figure
Doubly differential cross sections for ionization of lithium atom by protons and O ions
We consider single ionization of lithium atom in collisions with and
O projectiles. Doubly differential cross sections for ionization are
calculated within a relativistic non-perturbative approach. Comparisons with
the recent measurements and theoretical predictions are made.Comment: Submitted to the Topical Issue of Eur. Phys. J. D based on the
contributions reported on the International Conference on Many Particle
Spectroscopy of Atoms, Molecules, Clusters and Surfaces (MPS 2018), Budapest,
Hungary, 21-24 August 201
Strong exciton-plasmon coupling in semiconducting carbon nanotubes
We study theoretically the interactions of excitonic states with surface
electromagnetic modes of small-diameter (~1 nm) semiconducting single-walled
carbon nanotubes. We show that these interactions can result in strong
exciton-surface-plasmon coupling. The exciton absorption line shape exhibits
Rabi splitting ~0.1 eV as the exciton energy is tuned to the nearest interband
surface plasmon resonance of the nanotube. We also show that the quantum
confined Stark effect may be used as a tool to control the exciton binding
energy and the nanotube band gap in carbon nanotubes in order, e.g., to bring
the exciton total energy in resonance with the nearest interband plasmon mode.
The exciton-plasmon Rabi splitting we predict here for an individual carbon
nanotube is close in its magnitude to that previously reported for hybrid
plasmonic nanostructures artificially fabricated of organic semiconductors on
metallic films. We expect this effect to open up paths to new tunable
optoelectronic device applications of semiconducting carbon nanotubes.Comment: 22 pages, 8 figures, accepted for PR
Spontaneous decay of excited atomic states near a carbon nanotube
Spontaneous decay process of an excited atom placed inside or outside (near
the surface) a carbon nanotube is analyzed. Calculations have been performed
for various achiral nanotubes. The effect of the nanotube surface has been
demonstrated to dramatically increase the atomic spontaneous decay rate -- by 6
to 7 orders of magnitude compared with that of the same atom in vacuum. Such an
increase is associated with the nonradiative decay via surface excitations in
the nanotube.Comment: 8 pages, 3 figure
Патологии метаподий древних копытных
This report describes pathological changes of twelve metapodial bones of ancient large ungulates (Bison priscus, Cervus elaphus, Megaloceros giganteus, Equus ex gr. gallicus) from various sites in West Siberia. Two basic types of deteriorations were observed: proximal epiphyseal deformity resulting from arthrosis, and periosteal proliferations on diaphysis. All of these likely are related to trauma. The most probable causes of the injuries include unsuccessful hunting activity of cave lions and environment-associated sharp or blunt force
Phosphate limitation triggers the dissolution of precipitated iron by the marine bacterium Pseudovibrio sp. FO-BEG1
Phosphorus is an essential nutrient for all living organisms. In bacteria, the preferential phosphorus source is phosphate, which is often a limiting macronutrient in many areas of the ocean. The geochemical cycle of phosphorus is strongly interconnected with the cycles of other elements and especially iron, because phosphate tends to adsorb onto iron minerals, such as iron oxide formed in oxic marine environments. Although the response to either iron or phosphate limitation has been investigated in several bacterial species, the metabolic interplay between these two nutrients has rarely been considered. In this study we evaluated the impact of phosphate limitation on the iron metabolism of the marine bacterium Pseudovibrio sp. FO-BEG1. We observed that phosphate limitation led to an initial decrease of soluble iron in the culture up to three times higher than under phosphate surplus conditions. Similarly, a decrease in soluble cobalt was more pronounced under phosphate limitation. These data point toward physiological changes induced by phosphate limitation that affect either the cellular surface and therefore the metal adsorption onto it or the cellular metal uptake. We discovered that under phosphate limitation strain FO-BEG1, as well as selected strains of the Roseobacter clade, secreted iron-chelating molecules. This leads to the hypothesis that these bacteria might release such molecules to dissolve iron minerals, such as iron-oxyhydroxide, in order to access the adsorbed phosphate. As the adsorption of phosphate onto iron minerals can significantly decrease phosphate concentrations in the environment, the observed release of iron-chelators might represent an as yet unrecognized link between the biogeochemical cycle of phosphorus and iron, and it suggests another biological function of iron-chelating molecules in addition to metal-scavenging
Relativistic calculations of the U91+(1s)-U92+ collision using the finite basis set of cubic Hermite splines on a lattice in coordinate space
A new method for solving the time-dependent two-center Dirac equation is
developed. The approach is based on the using of the finite basis of cubic
Hermite splines on a three-dimensional lattice in the coordinate space. The
relativistic calculations of the excitation and charge-transfer probabilities
in the U91+(1s)-U92+ collisions in two and three dimensional approaches are
performed. The obtained results are compared with our previous calculations
employing the Dirac-Sturm basis sets [I.I. Tupitsyn et al., Phys. Rev. A 82,
042701 (2010)]. The role of the negative-energy Dirac spectrum is investigated
within the monopole approximation
Study of antimicrobial activity and technology optimization of Calendulae flos galenicals
The article presents materials on optimization of manufacture technology for Calendulae flos galenicals with medium level of antibacterial activity. For antibacterial study of extracts, we used agar well diffusion method. In our research, we utilized six test-strain microorganisms: E. coli ATCC 25922, S. aureus ATCC 25923, P. vulgaris ATCC 4636, P. aeruginosa ATCC 27853, C. albicans ATCC 885/653, and B. subtilis ATCC 6633. We have found that the maximum level of extracts’ antimicrobial activity is achieved in the range of ethanol content in the extractant from 70 to 97 % v/
- …