International Journal of Modern Physics B

It is known that processes occurring in binary system melts affect the crystallization process and the phase composition of alloys. To predict these processes, we should determine the region of thermodynamic stability of the melt. In this paper, the structural properties of hypoeutectic and hypereutectic alloys in Al–Cu system are studied depending on the heating temperature above the liquidus line and aftercooling rate. It is shown that overheating of Al–Cu melts to 150 K above the liquidus line and further cooling leads to complete suppression of the process of formation of primary aluminum crystals in hypoeutectic alloys and ${\mathrm{\text{Al}}}_2\mathrm{\text{Cu}}$ phase in hypereutectic alloys. For the first time, by accounting in Gibbs energy of binary Al–Cu alloy for the first degree approximation of high-temperature expansion of thermodynamic potential, the dependence of temperature of line of the melt thermodynamic stability on copper content in alloy is obtained.

To determine the optical parameters of crude oil and seawater systems, we carried out spectral investigations using the ellipsometry method, which is a highly sensitive and accurate optical method for studying the surfaces and interfaces of various media. This method is based on studying the change in the polarization state of reflected light after its interaction with the surface of interfaces of these media. Crude oil and seawater from different regions of Caspian Sea were accessed by spectroscopic ellipsometry over the 200–1700 nm spectral range at room-temperature. Optical constants and dielectric function were obtained for massive samples of each substance, as well as for ultrathin layers of the oil spilled over the sea surface. Dielectric function, when completely determined in the frequency regions corresponding to electronic transitions and excitation of atomic or molecular vibrations in the object, is a unique dielectric fingerprint of this object. Oils with even miserable difference in type and concentration of biomarkers and heterocomponents will have different dielectric functions. The possibility to use dielectric function as a unique optical fingerprint for oil identification is figured out.

In this research, we propose a novel construction of quantum stabilizer code based on a binary formalism. First, from any binary vector of even length, we generate the parity-check matrix of the quantum code from a set composed of elements from this vector and its relations by shifts via subtraction and addition. We prove that the proposed matrices satisfy the condition constraint for the construction of quantum codes. Finally, we consider some constraint vectors which give us quantum stabilizer codes with various dimensions and a large minimum distance with code length from six to twelve digits.

The laser damage resistance of fused silica optics depends significantly on the surface quality. In this work, anisotropic etching with inert ion beams at various ion incident angles was performed to investigate the evolution of the fused silica surface. The results show that the surface is smoothed when the incident angle is below $30^{\circ }$. However, the fused silica surface starts to become coarse owing to the formation of nanostructures on the surface when the incident angle exceeds $30^{\circ }$. Further, ion beam etching at a large incident angle of $70^{\circ }$ removes subsurface defects and less induces nanostructures, resulting in reduction of the surface roughness. The concentrations of impurities and defects are both significantly reduced after ion beam etching. The surface quality, subsurface and surface defects, and surface impurities determine the variation in the laser damage threshold of fused silica with the ion incident angle. The results demonstrate successful application of ion beam etching to improve the laser damage resistant characteristics of fused silica optics. Ion beam etching is a very versatile tool that provides physical erosion to anisotropically mitigate surface damage of fused silica.

Data processing with multiple domains is an important concept in any platform; it deals with multimedia and textual information. Where textual data processing focuses on a structured or unstructured way of data processing which computes in less time with no compression over the data, multimedia data are processing deals with a processing requirement algorithm where compression is needed. This involve processing of video and their frames and compression in short forms such that the fast processing of storage as well as the access can be performed. There are different ways of performing compression, such as fractal compression, wavelet transform, compressive sensing, contractive transformation and other ways. One way of performing such a compression is working with the high frequency component of multimedia data. One of the most recent topics is fractal transformation which follows the block symmetry and archives high compression ratio. Yet, there are limitations such as working with speed and its cost while performing proper encoding and decoding using fractal compression. Swarm optimization and other related algorithms make it usable along with fractal compression function. In this paper, we review multiple algorithms in the field of fractal-based video compression and swarm intelligence for problems of optimization.

Nanopores formed in insulating solid state membrane is of great importance in many fields such as detection of DNA/RNA molecules in their internal environment, probing and manipulating biopolymers. Here, we present an effective and convenient method to form nanopores in diamond etched by self-assembled Ni or Cu nanoparticles in hydrogen atmosphere. With our method, homogeneous nanopores with lateral size in the range of $0.5$–$1\mu \mathrm{\text{m}}$ were created without using Reactive Ion Etching (RIE) process. In this work, the etching pits of Ni and Cu etched diamond were investigated, respectively. A novel step-like pattern of etching pits was observed on diamond etched by Ni. In order to study the etching process and figure out the etching mechanism of diamond, Scanning Electron Microscopy (SEM) was used to observe the etching morphology. Atomic Force Microscopy (AFM) and Laser Scanning Confocal Microscope (LSCM) were used to visualize the image of diamond etching pits and investigate the step-like pattern. A fixed step height was observed in each pit. Based on these observations and findings, a hypothesis is proposed, which can help to provide a new controllable etching method.

Using Monte Carlo Basin-hopping algorithm within the Gupta potential, a systematic investigation has been performed for the best chemical ordering structures of 19-atom trimetallic ${\mathrm{\text{Pd}}}_n{\mathrm{\text{Ag}}}_{(17-n)}{\mathrm{\text{Pt}}}_2$ nanoclusters with double icosahedral geometry. The structures with the lowest energy at Gupta level are then re-optimized by DFT relaxations and the DFT relaxations confirmed the lowest energy structures obtained at the Gupta level indicating the double icosahedron structure is favorable for 19-atom ${\mathrm{\text{Pd}}}_n{\mathrm{\text{Ag}}}_{(17-n)}{\mathrm{\text{Pt}}}_2$ nanoclusters. It was observed that the caloric curves exhibit a smoother transition with structural isomerizations other than a sharp jump behavior.

In this study, the effects of Cu nanoparticles on the melting characteristics, wettability, interfacial reaction and mechanical properties of $\mathrm{\text{Sn}}$–$\mathrm{\text{xCu}}$ $(x=0$, $0.3$, $0.7$, $1.0$, $1.5$, $2.0)$ composite solders were investigated. Results show that the properties of the composite solder containing Cu nanoparticles were improved effectively. With the addition of Cu nanoparticles, the melting point of $\mathrm{\text{Sn}}$–$\mathrm{\text{xCu}}$ solder decreased significantly, and the spreading area and the shear strength were increased by 10.3% and 23.2%, respectively. For the performance, the optimal addition of Cu nanoparticles was 0.7%. In addition, the growth of interfacial intermetallic compounds in $\mathrm{\text{Sn}}$–$\mathrm{\text{xCu/Cu}}$ solder joints was inhibited by adding Cu nanoparticles.

We investigate the radiation from a charged particle rotating around a dielectric cylinder with a negative real part of dielectric permittivity. For the general case of frequency dispersion in dielectric permittivity, expressions are derived for the electric and magnetic fields and for the angular density of the radiation intensity on a given harmonic. Compared with the case of a cylinder with a positive real part of the permittivity, new interesting features arise in the nonrelativistic limit and for the radiation at small angles with respect to the cylinder axis. Another feature is the appearance of sharp narrow peaks in the angular density of the radiation intensity for large harmonics. We analytically estimate the height, width and the location of these peaks. The influence of the imaginary part of dielectric permittivity on the characteristics of the peaks is discussed. The analytical results are illustrated by numerical examples. We show that the radiation intensity on a given harmonic, integrated over the angles, can be essentially amplified by the presence of the cylinder.

We study the dynamics of classical-quantum correlations in the nonadiabatic regime, using the rotating wave approximation (RWA), between two movable mirrors of two spatially separated Fabry–Pérot cavities, each of the two cavities having a movable end-mirror and coupled to a two-mode squeezed light from spontaneous parametric down-conversion. This work completes our previous work [M. Amazioug, M. Nassik and N. Habiballah, Eur. Phys. J. D 72, 171 (2018)] where we have studied the transfer of quantum correlations in steady state. The Bures distance is used to quantify the amount of entanglement of the symmetrical squeezed thermal state, and the Gaussian quantum discord is considered to quantify the quantumness of the quantum correlations even though the two movable mirrors are separable. Furthermore, total correlations are quantified using quantum mutual information. Indeed, these three indicators depend mainly on the temperature of the movable mirror and the squeezing parameter in strong coupling regime.

The aim of this paper is to investigate the free and forced axial vibrations under the two various linear and harmonic axial concentrated forces in zigzag single-walled carbon nanotube (SWCNT). Two different boundary conditions, namely clamped–clamped and clamped-free, are established. Eringen’s nonlocal elasticity is employed to justify the nonlocal behavior of constitutive relations. The governing equation and the associated boundary condition are derived based on Hamilton’s principle. In order to solve the derived equation numerically, the assumed modes method is utilized. In the free axial vibration section, the first three natural frequencies are obtained for the various values of the nonlocal parameter. The results are in good agreement in comparison with another study. The fundamental natural frequencies with respect to the nonlocal parameter of the case study as a semiconducting nanotube with boron nitride nanotube (BNNT) as a semiconducting nanotube and SWCNT (5,5) as a metallic nanotube are compared. The effects of the nonlocal parameter, thickness and ratio of the excitation-to-natural frequencies overtime on dimensional and nondimensional axial displacements are studied.

We have grown orthorhombic barium disilicide (${\mathrm{\text{BaSi}}}_2$) thin-films on modified silicon (Si) substrates by a thermal evaporation method. The surface modification of Si substrate was performed by a metal-assisted chemical etching method. The effects of etching time $t_e$ on crystalline quality as well as optical and electrical properties of the ${\mathrm{\text{BaSi}}}_2$ films were investigated. The obtained results showed that substrate modification can enhance the crystalline quality and electrical properties; reduce the light reflection; and increase the absorption of the ${\mathrm{\text{BaSi}}}_2$ thin-films. The $t_e$ of 8 s was chosen as the optimized condition for surface modification of Si substrate. The achieved inferred short-circuit current density, Hall mobility, and minority carrier lifetime of the ${\mathrm{\text{BaSi}}}_2$ film at $t_e$ of 8 s were $38{\mathrm{\text{mA/cm}}}^2$, $273{\mathrm{\text{cm}}}^2/\mathrm{\text{Vs}}$, and $2.3\mu$s, respectively. These results confirm that the ${\mathrm{\text{BaSi}}}_2$ thin-film evaporated on the modified Si substrate is a promising absorber for thin-film solar cell applications.

A new method for analyzing the local reduced activation energy $w(T)$ of the impurity conductivity is applied to Ga-doped $p$-Ge samples with a constant compensation ratio of $K=0.3$ reported by Zabrodskii and Andreev [Int. J. Mod. Phys. B 8, 883 (1994)]. Here, the local reduced activation energy is defined as $w(T)=d(ln\sigma )/d(lnT)$, where $\sigma$ and $T$ denote conductivity and absolute temperature, respectively. The method enables us to deconvolute the $w(T)$ curve into contributions from different conduction mechanisms such as free-hole conduction, nearest-neighbor hopping (NNH) conduction and variable-range hopping (VRH) conduction. As a result, it is shown that both the power exponents of the pre-exponential factors of NNH and VRH conductivity tend to decrease with increasing impurity concentration.

Magnetorheological fluid (MRF) is a kind of suspension composed of a nonconducting magnetic liquid and small soft magnetic particles with high permeability and low hysteresis. The tensile mechanical properties of MRF reflect its important mechanical properties. In this study, a testing device is designed to investigate the tensile mechanical properties of MRF in accordance with the plate method theory. First, the magnetic field is selected to analyze the influence of different gap sizes on the magnetic field. The magnetic field strength decreases as the gap increases. Second, a testing platform for tensile mechanical properties is built, and the tensile mechanical properties of MRF are experimentally studied under different magnetic field strengths, tensile speeds and surface characteristics. Experimental results show that the stronger the magnetic field, the greater the tensile yield stress. The maximum tensile stress at different velocities is nearly the same. Different surface characteristics affect tensile stress.