مجله فیزیک کاربردی
سال چهاردهم شماره 3 (پیاپی 38، پاییز 1403)

In the present study, the computer simulation has been used to generate the (1+1) and (2+1) surfaces with two types of correlation function Gaussian and correlation function Exponential forms. For this aim, a random number generator is used to generate the surfaces with Gaussian height distribution with zero mean, and their correlation functions were assumed to have Gaussian and exponential formulas. The calculations have been done for isotropic and anisotropic surfaces.  For monofractal evaluation of rough surfaces, skewness and kurtosis values have been calculated for these (1+1) and (2+1) dimensional surfaces. Moreover, these values have been analyzed by the behavior of probability distribution of height. Also, the Hurst exponents of surfaces have been evaluated to study the irregularity and jaggedness of produced surfaces. Furthermore, the fractal dimension of these rough surfaces has been obtained to describe the complexity of the irregular fractal surfaces.

All human beings need healthy nutrition to grow, so the lack or excess of low-amount elements causes diseases in humans, for this reason, it is essential to know the presence of elements in food. Arak aluminum production factory is located next to Chogha village, so it is necessary to study the effects of this factory and other industries in the region on its agricultural products. In this study, the content of 11 elements was determined: aluminum, bromine, calcium, chlorine, iron, magnesium, manganese, potassium, sodium, scandium, and zinc in crops as wheat, barley, peas, beans and alfalfa prepared from the village of Chogha in the Arak region by neutron activation analysis, as well as 3 other elements, including arsenic, lead, and cadmium were determined by inductively coupled plasma analysis. Magnesium concentration from 1310 to 3970, manganese from 15.2 to 66.3, sodium from 14.2 to 1490, aluminum from 5.72 to 914, chlorine from 364 to 12000, calcium from 413 to 29600, bromine from 0.23 to 14.50, potassium from 4740 to 14700, iron from 10.1 to 1310.0, scandium from 0.033 to 4.02, zinc from 27.7 to 96.7, arsenic from 0.000 to 0.021, lead from 0.000 to 0.003 and cadmium from 0.00 to 0.02 mg/kg. The results show that the concentration of chlorine, manganese, magnesium, iron, sodium, aluminum, bromine, calcium, scandium, zinc, and lead in alfalfa, the concentration of potassium in pinto beans, the concentration of cadmium in barley, and the concentration of arsenic in wheat are higher than another analyzed sample.

This article aims to design and construct a plasma generation device using the surface dielectric barrier discharge method (SDBD) on a laboratory scale to produce a stable and uniform atmospheric pressure plasma layer. For this purpose, a copper electrode with a thickness of 100 microns with a comb- like structure was designed and constructed for this system, and a mica sheet with a thickness of 0.5 mm and dimensions of 10 × 10 cm was built to make the dielectric. According to the experimental data and analytical calculations of the constructed SDBD system in working conditions of 3 kV voltage and 12.5 kHz frequency, the consumption power of this system is calculated at 50 watts. Due to the production of stable and uniform plasma created on the dielectric surface and the measured power consumption, this system will be able to be used in various sciences and industries, including surface processing industries.

In this paper, the transport properties of a phosphorene nanoribbon with zigzag edges are investigated. Although phosphorene is a two-dimensional structure with gaps, each zigzag edge of phosphorene nanoribbon acts like a one-dimensional quantum wire, so a nanoribbon with two edges is similar to two parallel quantum wires. We also show that by adding an impurity line between the upper and lower edges, we can create an impurity strip that can connect the upper edge to the lower edge. In other words, different inputs can be coupled to different outputs. To calculate coupling coefficients between inputs and outputs, we use the Lippmann-Schwinger formulation. The final results show that depending on the energy of the input state and the corresponding standing wave in the impurity band, the phenomenon of resonance or anti-resonance can be created in the dispersion between inputs and outputs. Besides the theoretical aspect of the proposed scheme presented in this article, it can be applied to make nanoswitches in practice.

Red phosphorus nanoparticles were synthesized on the surface of the silicon solar cell by PVD technique (condensation on the cell surface from the vapor phase). The red phosphorous deposition on the surface of the cells was repeated several times with different thicknesses of the phosphorous layer, and after each deposition procedure, the efficiency of the silicon solar cell was measured. The obtained results demonstrated that after the deposition of 340 nm of phosphorous, the efficiency of the cell increased from 5.86 to 7.08, and about a 21% relative increase in efficiency was achieved. Moreover, the layers' absorption spectra and photoluminescence spectrum show that red phosphorus nanoparticles absorbed UV light and emitted visible light in addition to UV. In other words, the phosphorous layer has shifted the UV light to the visible light wavelength. In this research, a monocrystalline silicon solar cell was used to increase efficiency, and amorphous red phosphorus was deposited on the surface of the silicon solar cell by the PVD technique. In addition, to perform optical spectroscopy, a glass slide was placed next to the cells in each deposition step. The results of optical spectroscopy of phosphorous layers also showed that the amount of UV light transmission in the sample with a 340 nm phosphorous layer is lower than the sample with a 50 nm phosphorous layer. And vice versa, the amount of UV light absorption is higher, in other words, thicker phosphorous layers pass UV light less and absorb it more.

Our knowledge about the origin and transformation mechanisms of the bright points in the solar network has a significant role in understanding the ejection of materials and the transfer of energy into the solar corona. Outside the active region of the Sun (AR), although it is called the Quiet Sun (QS), various types of small-scale bright phenomena constantly occur within the boundary of the super granular cells above the magnetic network. Knowing the bright points is an effective key in considering the solar spicules. In this research, we study the solar transition region bright points and examine their apparent velocities with the local correlation tracking Fourier (FLCT) method. The results illustrate that these points differ in apparent velocity direction and brightness. Their lifetime and average horizontal velocity were estimated at 100 s and 4 kms-1, respectively. Recently, a new group of solar spicules has been observed, those lifetimes are around 100 s, and show a typical horizontal velocity of 3-4 kms-1. According to the analysis of the two-dimensional, apparent velocity of the bright points on the rosettes of the network, these points can be the disk counterpart of the type II spicules. In addition, the analysis of the two-dimensional field of velocities shows rotations that can cause the excitation of Alfvenic pulses.

The purpose of this research is to investigate the group velocity of tunable two-dimensional photonic crystals. The first step considers a square lattice consisting of dielectric rods in the liquid crystal background. In the next step, this structure was rotated by 45 degrees and its photonic band structure was investigated. Then, by removing a row of dielectric material (silicon) rods a waveguide is made in the photonic crystal. The waveguide mode and the related group velocity of the waveguide mode were investigated. In the following, the effect of applying an external voltage and changing the refractive index of the background material on the group velocity was studied. Afterward, by applying geometrical changes to the size of waveguide side rods, the effect of mentioned geometrical change on the properties of the waveguide mode and the group velocity was investigated. The calculation results show that the group velocity is reduced and as a result, the group index is increased.  The investigations carried out show that quantitatively, by applying an external voltage in the ordinary waveguides, the range of changes in the group index is between 7 and 10, but by applying changes in modified waveguides, this quantity changes in the range of 14 to 27, which can be adjusted by applying an external electric field.

This study investigated the topological phase transition of InSb and InBi under a non-hydrostatic lattice using density functional theory and the WIEN2K code. The results of examining the band structure of InSb and InBi employing the mBJGGA exchange-correlation potential indicate that InSb is a semiconductor with a small band gap and normal band order at the Γ point. At the same time, InBi is a metal with band inversion at the Brillouin zone center. To transform these compounds into topological semiconductors, the lattice of these compounds is subjected to non-hydrostatic lattice expansion. Non-hydrostatic lattice expansion is applied in two ways. Firstly, the lattice constants are expanded in the ab plane while keeping the lattice constant along the c-axis constant. Then, the lattice constant is expanded along the c-axis while keeping the lattice constant in the ab plane constant. The calculations indicate that under the influence of both types of non-hydrostatic lattice expansion, with the breaking of cubic symmetry, a transition towards topological semiconductors occurs.

In this work, detection probability of the orbital angular momentum (OAM) states of the Bessel-Gaussian (BG) and Laguerre-Gaussian (LG) beams passing through a plasma sheath turbulence (PST) are theoretically investigated. For this purpose, OAM-spectrum of the vortex beams (VB) is derived by using the modified von-Karman spectrum in the frame of Rytov theory, then some numerical analysis is performed to show the difference of considered VBs in the propagation through a PST. Obtained results indicate that incident beam parameters such as angular mode number, beam waist, and wavelength can easily affect the OAM-spectrum of both types of VBs. As well as, increasing the anisotropic parameters of the turbulent media can mitigate the turbulence-induced disturbance of the propagated VBs. Furthermore, it is found that diffraction-free BG beams show a better propagation performance than LG beams in the PST. This feature allows the BG beam to be a good candidate for free-space communication applications.