Adiabatic Brownian motor with a stepwise potential perturbed by a dichotomous harmonic sygnal

We obtained an analytical expression for the average motion velocity of an adiabatic Brownian motor (ratchet), which operates due to small dichotomous spatially harmonic fluctuations of a stepwise potential. The symmetry properties of the average velocity as a functional of the stationary and fluctuating components of the nanoparticle potential energy are revealed, and the ranges of values of the system parameters that ensure the rightward and leftward motion of the motor are determined. We showed that the average motor velocity is a non-monotonic function of the stepwise potential height. For a singular (infinitely high and narrow) potential barrier, the average velocity depends non-monotonically on the «power» of this barrier (the barrier width multiplied by the exponent of the ratio of the barrier height to the thermal energy). The article continues the further development of theoretical methods of symmetry analysis by applying the general approaches proposed by the authors to specific motor systems.

TUNABLE CLOAKING OF MEXICAN-HAT CONFINED STATES IN BILAYER SILICENE

We present the ballistic quantum transport of a p-n-p bilayer silicene junction in the presence of spin-orbit coupling and electric field using a four-band model in combination with the transfer-matrix approach. A Mexican-hat shape of low-energy spectrum is observed similarly to bilayer graphene under an interalayer bias. We show that while bilayer silicene shares some physics with bilayer graphene, it has many intriguing phenomena that have not been reported for the latter. First, the confined state producing a significantly non-zero transmission in Mexican hat. Second, the cloaking of the Mexican-hat confined state is found. Third, we observe that the Mexican-hat cloaking results in a strong oscillation of conductance when the incident energy is below the potential height. Finally, unlike monolayer silicene, the conductance at large interlayer distances increases with the rise of electric field when the incident energy is above the potential height.

Evaluation of the transformation potential of urbanised landscape (Vilnius case).

The article analyzes the evaluation of the transformation potential of valuable urbanised landscape. Many of the old towns formed as valuable urbanised landscapes. However, the transformation of urban structures of viable cities, which also entails transformation of urbanised landscapes, is inevitable. Basically, there are only two ways of transformation – either it happens in its own way or it can be professionally controlled. In this article the problem of urbanised landscape transformation is illustrated by the analytical work carried out for the eastern part of the Old Town of Vilnius (UNESCO heritage site). In the eastern part of the Old Town of Vilnius there are two architectural ensembles that form the characteristic panoramas and silhouettes of the Old Town. In this part of the city, various new built-up initiatives have been active since 2007. The article discusses the urban research, the purpose of which was to answer the question about the potential height of the newly designed built up in a former historic suburb of Vilnius. The potential impact of new buildings on the panoramas, silhouettes, dominant elements, and perspectives as well as nominal spaces of that concrete street of the historical suburb is assessed based on the analysis of the towns cape seen from typical external and internal viewing points of the Old Town. The article describes an integrated method of assessing visual effect on the urbanised landscape.

Universal ratio of Coulomb interaction to geometric quantization in (In, Ga)As/GaAs quantum dots

We study the photoluminescence of self-assembled (In,Ga)As/GaAs quantum dot ensembles with varying confinement potential height. The low energy shift of the s -shell emission with increasing excitation power gives a measure of the Coulomb interaction in these structures as it results from carrier–carrier interactions between the optically injected exciton complexes. When dividing this shift by the dot level splitting, determined by the geometric confinement, we obtain a universal function of the number of involved excitons that is independent of the confinement potential height. This shows an identical scaling of Coulomb interaction and geometric quantization with varying confinement.

Study of strong-coupling impurity bound polaron in a quantum pseudodot

In the present work, we have studied the first internal excited state energy and transition frequency of strong-coupling impurity bound polaron in a quantum pseudodot using the well-known Lee–Low–Pines (LLP) unitary transformation method. We show the effect of Coulomb bound potential, electron–phonon (e–p) coupling strength, the quantum dot radius and potential height on first internal excited state energy and the transition frequency of the impurity bound polaron. According to the results, it is found that the first internal excited state energy is decreased with increasing quantum dot radius. Also, this energy is increased with enhancing potential height. The transition frequency is increased with increasing the e–p coupling strength. Also, the first internal excited state energy is increased with decreasing the e–p coupling strength. The transition frequency is enhanced with increasing the Coulomb bound potential.

Theoretical Study of Charge Transfer in Styryl Thiazilo Quinoxaline Dyes STQ-1, STQ-2,and STQ-3 in Organic Media System

Charge transfer in styryl dyes STQ-1, STQ-2,and STQ-3 with organic media system has been studied theoretically depending on the Franck- Condon rule and continuum dielectric model . The reorientation energies (eV) were evaluated theoretically depending on dipole momentum, dielectric constant , and refrective index n. The rate constant of charge transfer has been calculated depending on the reorientation energy (eV) ,effective free energy , potential height barrier , and coupling coefficient . A matlap program has been written to calculated the rate constant of charge transfer and other parameter. The results of calculations show that STQ-2 dye is more reaction for charge transfer compare with STQ-1 and STQ-3 dyes