International Journal of Modern Physics B最新文献

In this study, tantalum carbide (TaC) samples were placed in a diamond anvil cell to study the equation of state at room temperature and high pressure using synchrotron radiation X-ray diffraction. By fitting the data at ambient pressure and up to the highest pressure of 38.5$$GPa, we obtained the bulk modulus and first derivative of TaC as $K_0=290.7$ (6.8) GPa and $K_0^{\prime }=3.05$ (0.49), respectively. In addition, we calculated the bulk modulus and band structure of TaC under high pressure using density functional theory. The obtained bulk modulus is 267 (3)$$GPa. TaC is metallic in nature throughout the entire pressure range. We studied the high-pressure deviatoric stress of TaC using linewidth analysis method. We found that TaC can support a maximum differential stress of up to 18.6$$GPa at the highest pressure of 38.5$$GPa.

Directed transport of self-propelled ellipsoidal particles confined in a smooth corrugated channel with asymmetric potential and Gaussian colored noise is investigated. Effects of the channel, potential and colored noise on the system are discussed. Large noise intensity in the x-axis direction inhibits the transport in $-x$ and $+x$ directions. The directed transport speed $|〈V〉|$ has a maximum with increasing noise intensity in the y-axis direction. Proper size of the bottleneck is good for the directed transport of the ellipsoidal particles, but large or small size of bottleneck inhibits this directed transport. The transport reverse phenomenon appears with increasing load and self-propelled speed. Confined spherical particle is easier to produce directed transport than confined needlelike ellipsoid particle.

Increasing demand for advanced technologies that depends on magnetic phenomena, understanding and controlling the behavior of discrete breather in ferromagnetic nanowires are crucial for enhancing the efficiency and performance of such devices. The presence of octupole–dipole interactions signifies a unique aspect that could potentially influence the stability and localization of breather excitations. Hence, we adopted a multifaceted approach to investigate the Heisenberg anisotropic ferromagnetic nanowire discrete model with the following interactions: bilinear, octupole–dipole, anisotropy and its higher-order terms. The dynamics is governed by a discrete nonlinear Schrödinger equation (DNLS) arrived with the aid of Holstein–Primakoff transformation. This transformation was facilitated by utilizing the Glauber coherent representation of the boson operators. Subsequently, the dynamical equation is incorporated to the Modulational Instability (MI) analysis which is a systematical gateway to explore the breather excitation in the region of instability influenced by the octupole–dipole interaction coupling parameter. Then, we pictorially demonstrated that the octupole–dipole interaction plays a pivotal role in promoting the localization of discrete breather on the surface of the spin lattice sites in the discrete ferromagnetic nanowire. The energy density distribution also implies that the increase in octupole–dipole interaction results in the highly dense breather localization. The result shows that the increment in the octupole–dipole interaction parameter increases the amplitude of the localized breathers. These discrete breathers could hold immense promise for applications in magnetic storage and Spintronic devices, where maintaining stable localized modes is crucial for the device functionality. Our novelty lies in being pioneers in the exploration of a fully discrete model that encompasses higher-order interactions, such as the octupole–dipole interaction. We already have confirmed the existence of instability region on the discrete spin lattice by incorporating the octupole–dipole interaction [T. Pavithra, L. Kavitha, Prabhu and A. Mani, Modulational instability analysis in an isotropic ferromagnetic nanowire with higher order octopole-dipole interaction, in Nonlinear Dynamics and Applications: Proceedings of the ICNDA 2022 (Springer, 2022), p. 1209], we attempting to explore the generation of discrete breathers in a discrete anisotropic ferromagnetic nanowire. This effectively bridges the gap between theoretical understanding and practical implications, paving the way for innovative advancements in magnetic technology.

Studying real-world problems with flow models of Newtonian and non-Newtonian fluids has gained particular attention because of its significance in engineering and other industries. According to trends in the field of research, interest in studying the characteristics of all such fluid flows is expanding. Due to the peculiar nature of the physical foundation of these non-Newtonian flows, no single constituent equation is available in the literature to explain all of their characteristics or rheological behavior. In the current investigation, the continuous 2D Casson fluid heat transfer flow is combined with the effects of radiation and an inclined magnetic field over a linear stretch surface. Newtonian condition is used to heat the sheet. The governing partial differential equations (PDEs) are transformed into nonlinear ordinary differential equations (ODEs) via the similarity transformation. The fourth-fifth-order Runge–Kutta Fehlberg (RKF45) method is then used to numerically solve the problem. The results for temperature distribution, and velocity field are computed and plotted graphically and discussed in detail. It is found that the magnetic parameter reduces fluid velocity and the Casson fluid parameter increases temperature distribution.

This paper analyzes the thermodynamic second law analysis of mixed convection heat transfer of Carboxymethyl Cellulose (CMC)-water based viscoelastic hybrid nanofluid flow in a vertical parallel plate channel filled with porous medium. In mixed convection flow, where both buoyancy and viscous forces play significant roles in the flow behavior, the inclusion of viscous dissipation in the analysis is crucial. The governing equations of the problem are converted into a system of ordinary differential equations using appropriate similarity transformations, which are then solved by the Homotopy Analysis Method (HAM). The behavior of non-dimensional velocity, temperature, skin friction coefficient, Nusselt number, entropy generation and Bejan number profiles for a range of pertinent flow parameter values is displayed graphically and deliberated. Study reveals that a decrease in the dominance of viscous forces relative to inertial forces within the porous medium lowers entropy generation in the system.

A computational study was conducted using the density functional theory (DFT) method to determine the energy stability of a system composed of deoxyribonucleic acid/ribonucleic acid (DNA/RNA) nucleobase molecules on Fullerene C${}_{60}$ as a potential gene delivery system. The feasibility of the system for gene delivery and nanomedicine applications was assessed by examining the strong geometric bonds formed between Adenine, Cytosine, Guanine, Thymine, and Uracil nucleobases and C${}_{59}$Si molecules in close proximity to Fullerene. The bonding affinities of each nucleobase with Fullerene were observed to follow the order Uracil > Guanine > Cytosine > Thymine > Adenine. Furthermore, calculations of adsorption and formation energies were performed to determine the most stable configuration within the Fullerene structure. Guanine demonstrated the highest stability, indicating its potential as an efficient carrier for the delivery of guanine-based genetic material into cells. Additionally, the Fullerene surface exhibited a high propensity for Cytosine adherence, as evidenced by the lowest adsorption energy observed for the interaction between Cytosine and Fullerene. The potential application of Si-doped Fullerene C60 as a gene delivery system was highlighted, based on the strong interactions observed with DNA/RNA nucleobase molecules. These valuable insights will contribute to the development of efficient gene delivery strategies and offer promising prospects for advancing gene therapy and nanomedicine.

Two-dimensional heterostructures based on transition metal dichalcogenides (TMDs) exhibit broad application prospects in valleytronics due to the space-reversal symmetry breaking and strong spin–orbit coupling. In this work, the electronic structure, magnetic anisotropy and valley polarization of 2H–WSSe/VN van der Waals heterostructure under various interlayer spacings, magnetic angle and in-plane strain are investigated in detail by first-principles calculations. The stacked configuration of Se-C2-1 with most stable structure shows the largest valley polarization of 386.5$$meV. By adjusting the interlayer spacing of heterostructure, the largest valley polarization of 702.7$$meV appears in Se-C2-1 stacked configuration with interlayer spacing of 2.24 Å. The magnetic angle $\theta$ exhibits significant effects on valley polarization and magnetic anisotropy of 2H–WSSe/VN heterostructures. The stability and valley polarization of 2H–WSSe/VN heterostructure decrease after the in-plane biaxial strain is applied. The large and tunable valley polarization as well as magnetic anisotropy in the 2H–WSSe/VN heterostructures make it potential applications in valleytronic devices.

Many projectiles tend to spin about their longitudinal axis while progressing in the forward direction. It helps in providing stability and a reference direction for guidance during their run. Many different projectiles employ a supersonic convergent-divergent nozzle to produce thrust for their forward motion; hence, the nozzle and overall whole propulsion system tend to spin about its axis of rotation. The main aim of this study is to observe the effect of spin on the nozzle. In this research, a converging bell-shaped diverging nozzle is numerically designed using a method of characteristics (MOC) for exit Mach number 3.21. Viscous simulations are performed for both two- and three-dimensional cases. The analysis is then performed with nozzle spinning about its axis of symmetry with a constant angular velocity of 10 revolutions per second. The analysis is repeated for the value of constant angular velocities to be 15 and 20 revolutions per second, and the behavior of flow with increasing angular velocity is examined. It has been observed that the exit Mach number and velocity decrease due to the radial protrusion of the boundary layer, and it has a negative impact on the performance of the nozzle. Moreover, the decrease of exit Mach number is in direct relation to increasing angular velocity.

This paper focuses on the heat and mass transfer characteristics of a steady laminar planar jet flow of a Maxwell-power-law (MPL) fluid. MPL is a renowned fluid model with shear thinning and viscoelastic characteristics that can accurately exhibit the rheological features of polymer liquids. In the envisioned study, the MPL constitutive equation is introduced based on an experiment utilizing the Xanthan gum solution. The heat and mass equations are supported by the Cattaneo–Christov double diffusion (CCDD) concept with unique characteristics of thermal conductivity, mass diffusion, and chemical reaction. Thermal conductivity and mass diffusion coefficient are considered to be velocity gradient-dependent. The problem is addressed numerically by the bvp4c method in Matlab after applying the similarity transformations to the governing equations. The impacts of related parameters on velocity, temperature, and concentration are analyzed. Results show that an upsurge in the power-law index hinders momentum, energy, and mass transmission. An interesting phenomenon is that the variation in relaxation time can hinder or promote the heat and mass transfer of a Maxwell-power-law fluid jet before or after the intersection point, respectively. The study can provide a theoretical reference for engineering applications of jets.