نشریه پژوهش سیستم های بس ذره ای
سال سیزدهم شماره 3 (پیاپی 38، پاییز 1402)

This research investigates the photocatalytic activity of mechanically alloyed graphite-iron- titanium powder for the removal of Eriochrome Black-T dye pollution. The structural and optical properties of the alloys are evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy diffraction spectroscopy (EDX), and ultraviolet-visible spectroscopy (UV-vis). X-ray diffraction measurements show that after 35 hours of milling time, the intensity of the element’s peaks decreases, along with the increase of peaks width. The average iron crystallite size is estimated to be approximately 50.8 nanometers. The morphology of the alloyed powders shows that the particles are flattened and plate-like in shape, which is suitable for absorption and photocatalytic activities. Fifteen photocatalytic experiments are designed to remove dye pollution; the optimal dye removal’s parameters for pH, lamp power, and alloy dosage (g/L) are obtained using the combination of artificial neural network, and genetic algorithm (ANN-GA). With optimal conditions, the maximum removal rate is determined to about 86.4%.

In this paper, based on the transfer matrix method and within the free electron approximation, we study spin-dependent electronic transport through an array of magnetic quantum barriers. For this purpose, we first write the Schrodinger equation for the electron in the presence of barrier potentials and the magnetic field originating from system magnetic moments. Then, by its discretization, we reach a system of linear equations. In the following, by using the transfer matrix method for this system of equations, we obtain the spin-dependent transmission coefficients of the electron. With the help of present formalism, one can calculate the spin-dependent transmission coefficient of a transmitted electron through a magnetic multi-layer as a function of electron energy, magnitude and orientation of the magnetic moment, and the potential shape. Finally, as an example, the numerical results are presented for two cases, the one including two similar alternative magnetic barriers and the other including two alternative barriers and well. The presented method is useful for the study of the spin-dependent electronic conductance behavior of magnetic layers and superlattices.

Hypernuclei are known as the bound states of nucleons and one or more strange baryons (hyperons) so the development of their physics helps to understand the structure of nuclei and the properties of strange baryons with more precision. One important goal in the field of hypernucleus physics is the study of the interaction of hyperon-nucleon and hyperon-hyperon. In this regard, the study of hypernuclei structure can play an essential role in understanding these types of interactions. In this work, we study some important static properties of single-lambda hypernuclei (nuclei containing a -baryon) such as their binding energy and magnetic moments. For our calculation, we use the Dirac relativistic wave equation considering a spin-orbit potential and determine the analytical equation of binding energy and magnetic moments. In the following, we will determine these quantities for some light hypernuclei such as  and . Our analytical results will be compared with other theoretical results as well as available experimental data.

In this study, the stability and bifurcation analysis of nonlinear ion-acoustic waves is investigated in a non-Maxwellian plasma consisting of cold ions and Kappa-distributed electrons and positrons.  First, a characteristic equation for the evolution of ion-acoustic waves is obtained and then the stability of traveling wave solution on fixed points-energetic positron density plane is discussed numerically. It is found that the motion dynamics of homoclinic orbits and nonlinear periodic orbits undergo a transcritical bifurcation at the critical positron density , where two fixed points coalesce, and then switch their stabilities. The variations of the initial  and critical  positron concentrations versus a wide range of values of the spectral index of positrons  and electron-to-positron temperature ratio  are also studied. Furthermore, according to the phase portraits analysis, the coexistence of homoclinic orbits, nonlinear periodic, and super nonlinear periodic orbits is also investigated for different conditions. It is shown that the positron density and the temperature ratio of electron to positron play a crucial role in the propagation of nonlinear waves.

In this work, we study wormhole solutions described by a radial dependent red-shift function in Einstein-cubic gravity. We derive wormhole solutions by assuming a particular equation of state and check the standard energy conditions. These solutions by imposing suitable values the parameters of the theory satisfy the weak energy condition in the vicinity of the throat. We calculate the null and time-like geodesic equations in the space-time of the wormhole solutions. In addition, by using these solutions and the effective potential formalism, some geodesics are classified. We discuss the geodesics of the test particles and classify them according to the particle’s energy and angular momentum. Finally, using gravitational lensing effects, observational features of the wormhole structure are discussed.

In this article, we considered the effect of uniform acceleration on the quantum binomial state, which consists of a superposition of single-mode Fock states with binomial coefficients. In particular, we studied the nonclassical features of the quantum binomial state under Unruh effect. We obtained analytically various witnesses of nonclassicality such as squeezing, Mandel parameter, and Vogel’s criterion. We found that squeezing could be increased or decreased by the Unruh effect for different observers.  In addition, with the increase of the number of single-mode Fock states in the quantum binomial state, the squeezing increases. Moreover, we found the Mandel parameter and Vogel’s criterion which is a sufficient condition for the nonclassicality of the state and compared the results with the inertial observer.