Time filter

Source Type

Baghdasaryan D.A.,Russian-Armenian (Slavonic) State University | Hayrapetyan D.B.,Russian-Armenian (Slavonic) State University | Hayrapetyan D.B.,Yerevan State University | Harutyunyan V.A.,Russian-Armenian (Slavonic) State University
Physica B: Condensed Matter | Year: 2017

The electronic states and optical properties of spherical nanolayer in the presence of the electrostatic radial field in the strong size quantization regime have been considered. Both analytical and numerical methods have been applied to the problem of one-electron states in the system. According to the intensity of the external electrostatic field, three regimes have been distinguished: week, intermediate and strong. Perturbative approach have been applied to the case of week, WKB to the case of intermediate and variation approach to the case of strong field intensities. The analytical dependencies of the one electron energy and wave function on the electric field value and geometrical parameters of the nanolayer have been achieved. The comparison of the results obtained by the analytical method with the results of the numerical method have been made. The interband and intraband optical transitions caused by incident optical light polarized in z direction have been considered in this system. The selection rules for this transitions have been obtained. The dependence of the absorption coefficient on the energy of incident light for both cases of interband and intraband transitions for every regime of the electrostatic field value have been received. © 2017 Elsevier B.V.


Liang S.,Guangzhou University | Xie W.,Guangzhou University | Sarkisyan H.A.,Russian-Armenian (Slavonic) State University | Sarkisyan H.A.,Yerevan State University | And 2 more authors.
Superlattices and Microstructures | Year: 2012

Optical properties of a nanoring with Winternitz-Smorodinsky confinement potential in the presence of an external magnetic field have been studied theoretically. Our results demonstrate that energy, oscillator strength and the linear, nonlinear and total absorption are strongly affected by size of the nanoring. Also, we found that magnetic field has little influence on energy difference, oscillator strength and optical absorption of the nanoring. © 2012 Elsevier Ltd. All rights reserved.


Liang S.,Guangzhou University | Xie W.,Guangzhou University | Sarkisyan H.A.,Russian-Armenian (Slavonic) State University | Sarkisyan H.A.,Yerevan State University | And 2 more authors.
Journal of Physics Condensed Matter | Year: 2011

We have studied the nonlinear optical absorption and the nonlinear optical rectification of an exciton in a nanoring in the presence of magnetic flux. The calculation results show that one can control the properties of nonlinear optical absorption and nonlinear optical rectification of a nanoring by tuning the outer and inner radius. Moreover, we find that the nonlinear optical properties of a nanoring can be modulated by the magnetic flux through the nanoring. © 2011 IOP Publishing Ltd.


Torgomyan H.,Yerevan State University | Ohanyan V.,Yerevan State University | Blbulyan S.,Russian-Armenian (Slavonic) State University | Kalantaryan V.,Yerevan State University | And 2 more authors.
FEMS Microbiology Letters | Year: 2012

Exposure to electromagnetic irradiation (EMI) of 51.8 and 53.0 GHz and low intensity (flux capacity of 0.06 mW cm-2) for 1 h markedly decreased the energy-dependent H+ and K+ transport across membranes of Enterococcus hirae ATCC 9790. After EMI, there was also a significant decrease of overall and N,N'-dicyclohexylcarbodiimide (DCCD)-sensitive ATPase activity of the membrane vesicles. These measures were considerably lower at 53.0 GHz. EMI in combination with different antibiotics, such as ceftriaxone and kanamycin at their minimal inhibitory concentrations (100 and 200 μM, respectively), enhanced bacterial cell growth and altered their membrane transport properties. Total H+ efflux was most sensitive to ceftriaxone but DCCD-inhibited H+ efflux and total K+ influx were sensitive to kanamycin. The results indicate that cell membrane proteins could be a target in the action of EMI and enhanced antibacterial effects in combination with antibiotics. The DCCD-sensitive F0F1-ATPase or this ATPase in combination with K+ uptake protein probably plays a key role in these effects. © 2012 Federation of European Microbiological Societies.


Melikyan A.,Russian-Armenian (Slavonic) State University | Minassian H.,A Alikhanian National Scientific Laboratory | Grigoryan V.G.,Saarland University | Springborg M.,Saarland University
Applied Physics B: Lasers and Optics | Year: 2013

We develop an analytical approach to calculate the aspect ratios of free alkali metal clusters using measured surface plasmon frequencies. The method is based on the concept of small deviations from a spherical shape and can be applied to clusters with spheroidal, icosahedral and other shapes. Results of experimental data as well as of numerical calculations for the surface plasmon resonance frequencies in small spheroidal sodium clusters containing less than 50 atoms are reproduced accurately through a quite simple formula which links the aspect ratio of the cluster to the observable surface plasmon frequencies. The developed approach allows also to reveal the dependence of the dielectric function of alkali metal on the number of atoms in the cluster. © 2013 Springer-Verlag Berlin Heidelberg.


Madoyan K.,Russian-Armenian (Slavonic) State University | Melikyan A.,Russian-Armenian (Slavonic) State University | Minassian H.,Yerevan Physics Institute
Applied Physics B: Lasers and Optics | Year: 2010

We develop a new method based on the continuous-fraction approach as applied to the electrostatic boundary problem for determining surface plasmon resonances of coupled nanospheres. The resonance frequency dependence on interparticle gap (plasmon nanoruler effect) is determined by avoiding time-consuming numerical calculations even for very small interparticle separations, where known procedures face serious difficulties. Corrections due to retardation effects are accounted for, allowing description of larger nanopairs. Good agreement is demonstrated both with results of numerical calculations and with experimental data. © Springer-Verlag 2010.


Petrosyan L.S.,Jackson State University | Petrosyan L.S.,Russian-Armenian (Slavonic) State University | Shahbazyan T.V.,Jackson State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

We study resonant tunneling through a periodic square array of quantum dots sandwiched between modulation-doped quantum wells. If a magnetic field is applied parallel to the quantum dot plane, the tunneling current exhibits a highly complex Aharonov-Bohm oscillation pattern due to the interference of multiple pathways traversed by a tunneling electron. Individual pathways associated with conductance beats can be enumerated by sweeping the magnetic field at various tilt angles. Remarkably, Aharonov-Bohm oscillations are aperiodic unless the magnetic field slope relative to the quantum dot lattice axes is a rational number. © 2015 American Physical Society.


Petrosyan L.S.,Yerevan State Medical University | Petrosyan L.S.,Russian-Armenian (Slavonic) State University
Journal of Physics: Conference Series | Year: 2016

We study coherent transport in a system of periodic linear chain of quantum dots situated between two parallel quantum wires. We show that the resonant-tunneling conductance between the wires exhibits a Rabi splitting of the resonance peak as a function of Fermi energy in the wires. This effect is an electron transport analogue of the Rabi splitting in optical spectra of two interacting systems. The conductance peak splitting originates from the anticrossing of Bloch bands in a periodic system that is caused by a strong coupling between the electron states in the quantum dot chain and quantum wires.


Gasparyan V.A.,Russian-Armenian (Slavonic) State University
Advanced Materials Research | Year: 2013

In the effective-mass approximation the single-electron states in a direct-band CdS/β -HgS/CdS nanocylindrical heterolayer in the presence of strong lateral radial electrostatic field are considered. The explicit forms of the energy spectrum and envelope wave functions of singleparticle states for charge carriers are obtained using variation approach. Corresponding absorption characteristics of interband optical transitions in the layer in the presence of strong radial field are calculated. © (2013) Trans Tech Publications, Switzerland.


Hakobyan D.,Institute of Molecular Biology | Nazaryan K.,Institute of Molecular Biology | Nazaryan K.,Russian-Armenian (Slavonic) State University
Proteins: Structure, Function and Bioinformatics | Year: 2010

Phosphoglycerate mutase (PGM) and enolase are consecutive enzymes in the glycolytic pathway. We used molecular dynamics simulation to examine the interaction of human B-type PGM (dPGM-B) and neuron-specific enolase (NSE). Specifically, we studied the interactions of 31 orientations of these enzymes by means of the effective energy function implicit solvation method. Interactions between active regions of the enzymes occurred preferentially, although the strongest interactions appeared to be between the back side of NSE and the active regions of dPGM-B. Cleavage of 2PG from dPGM-B was investigated, and the Ser 14Leu 30 loop of dPGM-B is suggested as a cleavage site and, likely, another entrance site of a ligand. Substrate channeling between the enzymes was observed when NSE with its active regions Leu 11-Asn 16, Arg 49-Lys 59, and Gly 155-Ala 158 covered the Ser 14-Leu 30 loop of dPGM-B. Analyses of the results make us believe that the channeling between PGM and enolase "benefits" from weak interaction. The probability of formation of channeling favorable complex is estimated to be up to 5%, while functional interaction between NSE and dPGM-B might be as high as 20%. NSE and dPGM-B functional interaction seems not to be isotype specific. © 2010 Wiley-Liss, Inc.

Loading Russian-Armenian (Slavonic) State University collaborators
Loading Russian-Armenian (Slavonic) State University collaborators