Modern Physics Letters B

The study offers a thorough evaluation of the complex fluid dynamics and heat transfer phenomena in Williamson viscoelastic fluid flow, taking into account thermal radiations and variable thermal conductivity. The paper extends its analysis to include heat transfer effects, which are critical in several engineering and industrial applications, and digs into the complexity of non-Newtonian fluid behavior, with a special focus on thermal radiation, heat production, diffusion and viscous dissipation. The study makes use of mathematical models and numerical method RK4 to clarify the nonlinear interactions between convection and diffusion processes in this viscoelastic fluid. The energy and concentration equations are simulated in the presence of the modified Fourier and Fick laws. Moreover, the predicted heat flow is based on the Cattaneo–Christov theory. This research also sheds light on the interaction between rheological properties and thermal characteristics, providing important new knowledge to the broader field of fluid dynamics and heat transfer.

In this work, we have used the full-potential linearized augmented plane wave (FP-LAPW) method implemented in the WIEN2k code combined with the generalized gradient approximation (GGA) of the density functional theory (DFT) to study the structural, elastic, mechanical, electronic, magnetic, and thermodynamic properties of the parent ternary inverse Heusler compounds based on Titanium and Cobalt Ti₂CoGa, Ti₂CoCu in the Hg₂CuTi-type structure and their quaternary alloys Ti₂CoGa${}_{1-x}$Cu_x ($x=0.25$, 0.5, 0.75) for the chosen concentrations using a supercell with 16 atoms. We have calculated the structural properties, such as the lattice parameters, bulk modulus, and its first derivative, which are in good agreement with those that have been obtained based on other published theoretical methods. Also, we calculated the elastic constants of the studied Heusler alloys, and we found that these materials are elastically stable, ductile, and anisotropic. Therefore, the electronic and magnetic properties indicate that Ti₂CoGa exhibits a half-metallic (HM) ferromagnetic behavior, while Ti₂CoCu shows a metal and a non-magnetic (NM) character. Their quaternary alloys are found to be nearly HM ferromagnetic materials, with a magnetic moment mainly due to the atom Ti. Furthermore, the quasi-harmonic Debye model, which incorporates the lattice vibrations, was used to estimate the thermodynamic effects on some macroproperties of the Ti₂CoGa${}_{1-x}$Cu_x alloys. Successful results were achieved for the variations of the primitive cell volume, bulk modulus, heat capacities, and Debye temperature with pressure and temperature, respectively, in the ranges of 0–30GPa and 0–1400K. To our knowledge, no analogous investigations on the mechanical and thermodynamic properties of the Ti₂CoGa${}_{1-x}$Cu_x ($x=0.25$, 0.5 and 0.75) alloys have been performed to date. As a result, it is predicted that Ti₂CoGa${}_{1-x}$Cu_x Heusler alloys will be promising candidates for actual applications in spintronic devices.

This paper investigates the stagnation point flow of a second-grade nanomaterial, considering nanofluid effects via thermophoresis and Brownian motion. The study addresses convective heat and mass transfer conditions within the flow induced by a stretching cylinder. The transformed systems are solved using the optimal homotopy solutions (OHAM) method, revealing the impact of various parameters on the quantities of interest. The results indicate that an increase in curvature, viscoelasticity, velocity ratio and injection parameters leads to an enhancement in velocity, while the opposite trend is observed due to suction. The viscoelasticity and curvature parameters also increase skin friction. Additionally, thermophoresis enhances the temperature and concentration fields, while Brownian motion reduces mass diffusion.

Fano resonance sensors based on metal–insulator–metal (MIM) waveguide have potential applications in fields such as biology, chemistry, and the environment. Here, a nanosensor based on Fano resonance in an MIM-based isosceles triangular resonator system is proposed and numerically studied by finite element method. Simulation results show that the Fano peak can be easily tuned by adjusting the scale factor and the refractive index within the resonator. Furthermore, we thoroughly analyze the impact of the apex angle, rotation angle, and vertical displacement of the resonator on the transmission spectrum. Finally, the sensing characteristics of the proposed structure are optimized and analyzed, and a high-performance plasmonic sensor with a sensitivity of 1100nm/RIU and the maximum figure of merit of $5.46\times 10^9$ is obtained. The distinctive attributes of our suggested structure are applicable in the realization of various integrated components for the development of multifunctional high-performance nanophotonics devices.

In order to reduce friction between moving elements in automobiles’ heat exchange systems, SAE50 is a vital lubricant. Additionally, by preventing corrosion and abrasion of moving parts, it increases durability, reduces fuel consumption, and improves efficiency. SAE50 has a low thermal conductivity, despite this. The current inquiry is concentrated on how Zinc Oxide-Society of Automotive Engineers 50 nanolubricant flow (ZnO-SAE50 nanolubricant) through a permeable rotating disk is affected by a uniform horizontal magnetic field (UHMF) and thermal radiation. By employing the appropriate transformations, the governing modeled equations are changed into ordinary differential equations (ODEs). Then the ODEs are solved numerically by combining the Runge–Kutta-fourth-and-fifth Fehlberg’s (RKF-45) order and shooting tactic. The findings show that radiation is crucial in enhancing heat transfer for the flow of ZnO-SAE50 nanolubricant over the disk surface. With higher heat source/sink parameter values, it is discovered that the temperature boundary layer produces energy, causing thermal profiles to rise. Further in this scenario, it is found that the increase in magnetic field decreases the fluid flow gradually at rate of 5–10%.

Peristalsis of non-Newtonian nanofluid via a non-uniform conduit has several applications in physiology and industry. This study proposes a mathematical model as well as exploration of the impacts of entropy generation for peristalsis of magneto nanofluid with temperature-dependent thermal conductivity via an expanding asymmetric channel. Buongiorno’s model for study of nanofluid flow has been adopted. Rheological aspects are accounted using the Carreau–Yasuda model due to its experimentally validated significance. Impacts of applied electric and magnetic fields have been taken into account. Thermophoresis, ohmic heating, viscous heating and Brownian motion effects are incorporated in the model. Numerical method is used via NDSolve in Mathematica after implementing the lubrication approach and Debye–Huckel linearization. The effects of embedded parameters on the flow, heat transfer, entropy generation and Bejan number are studied using graphical depictions. Outcomes indicate that a rise in electroosmotic parameter enhances heat transfer rate, whereas it reduces entropy generation and mass transfer rate at the boundary. Therefore, this study can provide basics to study nanofluidic systems which has applications in drug delivery. Increasing trends for temperature, heat transfer rate and entropy generation, while declining trends in the concentration of the particles are noted for higher joule heating.

Using an electrospinning device, we determined the optimal conditions for producing nanofibers from a 10% solution of Co–AN. These conditions involved applying a 15kV voltage to the anode, which was connected to the syringe containing the solution, and maintaining a distance of 12–15cm from the needle tip to the collector screen (cathode). The filament diameter (d) ranged from 0.2 to 0.5mm. This setup allowed the formation of nanofibers under the cover. The electrolysis process was conducted for varying durations, ranging from 4 to 14h, while applying currents of 2mA, 4mA, and 8mA. At 4mA and 8mA, a substantial portion (approximately 65–70%) of the macroions in the solution reassembled on the electrode surfaces. These images clearly illustrate the restoration of macroions on the electrode surfaces, achieved through electron exchange processes. This phenomenon results in the combination of macroions and their neutralization, leading to the formation of a composite coating on the titanium, iron plate, and rods.

This research paper explores the structural, electronic, magnetic, elastic, dynamic, and thermoelectric properties of sp-based half-Heusler (HH) RbBaX ($X=\mathrm{\text{Si}}$ and Ge) compounds using density functional theory (DFT) and the full-potential linearized augmented plane wave (FP-LAPW) method within the WIEN2k software package. We evaluate the exchange correlation potential using two different approaches: The generalized gradient approximation (GGA) and the modified Becke–Johnson approach. We observe that RbBaX ($X=\mathrm{\text{Si}}$ and Ge) adopts a ferromagnetic configuration based on the analysis of total energy against volume. We establish that these alloys possess a genuine half-metallic character because of the full spin polarization observed at the Fermi level in their electronic spectrum. Both compounds under investigation have a total magnetic moment of 1.00$\mu$B, in agreement with the Slater–Pauling principle. The Born stability criteria for cubic structures and phonon dispersion patterns confirm the mechanical and dynamic stability of RbBaX ($X=\mathrm{\text{Si}}$ and Ge) alloys. The thermoelectric properties reveal a p-type semiconductor nature, characterized by significant positive Seebeck values. The thermoelectric figure of merit (ZT) calculated for both alloys at 300K approaches unity, highlighting their remarkable thermoelectric efficiency.

We show that several Hamiltonians that are ${𝒫}{𝒯}$ symmetric may be taken to Hermitian Hamiltonians via a non-unitary transformation and vice versa. Therefore, a recipe to produce tractable non-Hermitian Hamiltonians is given (a set of instructions to do it yourself). We also show that for some specific Hamiltonians such non-unitary transformations may be associated, via a fractional-Wick rotation, to complex time.

The electronic structures and optical properties of tetraborides RB₄ ($\mathrm{\text{R}}=\mathrm{\text{Nd}}$, Tb, Dy, and Er) are systematically investigated through the first-principles technique. The band structure and density of states (DOS) show that RM₄ has metal and magnetic characteristics. The DOS near the Fermi is dominated by R-4f states, which are responsible for the magnetic moments. The optical properties including refractive index, conductivity, absorptivity, reflectivity, and loss function are obtained based on the complex dielectric functions. The static dielectric constants and static refractive are presented. The absorptivity results indicate that tetraborides exhibit excellent optical absorption in the ultraviolet-visible (UV-Vis) regions. The reflectivity shows that RB₄ is an ideal near-infrared reflective material. This study provides theoretical insights into the optical applications of tetraborides.

This study analyzes how adding europium and transition metals (Cu, Ag, and Au) at a 12.5% concentration to magnesium oxide (MgO) affects its physical characteristics and potential uses. To do so, the full potential linearized augmented plane wave (FP-LAPW) method, based on spin-polarized density functional theory (SP-DFT), is used to derive the results. Wu and Cohen’s generalized gradient approximation (GGA-WC) described the exchange-correlation potential. The modified Becke-Johnson exchange potential (TB-mBJ) was also used to improve the findings of optoelectronic properties. When Eu and TM (Cu, Ag, and Au) impurities are co-doped into the nonmagnetic (NM) semiconductor MgO, the structural optimization results show that the lattice constants increase, and the bulk modulus decreases with increasing the atomic number of transition metals. The resulting dilute magnetic oxides (DMOs) are stable in the spin-polarized ferromagnetic (FM) phase, and the formation energy values confirm their stability in the $Fm\bar{3}m$ cubic structure, with the lowest value belonging to Eu${}_{0.125}$TM${}_{0.125}$Mg${}_{0.750}$O. Similarly, calculations of electronic properties using the WC-mBJ functional demonstrate that all compounds have an indirect half-metallic bandgap at L-$\mathrm{\Gamma }$ equal to 2.53, 2.49, and 1.39 eV for Eu${}_{0.125}$Cu${}_{0.125}$Mg${}_{0.750}$O, Eu${}_{0.125}$Ag${}_{0.125}$Mg${}_{0.750}$O, and Eu${}_{0.125}$Au${}_{0.125}$Mg${}_{0.750}$O, respectively. They have an integer magnetic moment of 6 ${\mu }_B$. The density of states shows that at the Fermi level, the 4f-Eu, d-TM, and p-O states give rise to new energy levels. This indicates that the f–p–d hybridization provides this system with its FM properties. Also, these compounds’ dielectric function and absorption spectra are calculated and analyzed to learn more about their optical properties. The results provide insight into the optical behavior of the materials. It is observed that the co-doped compounds exhibit greater optical absorbance than their un-doped MgO counterparts do. This theoretical investigation opens the way to preparing high magnetic moment DMOs using TM and rare earth as dopants suitable for spintronic and UV devices.

Heat and mass transfer acquired the attention of investigators and experts because of massive uses in the field of medicine, manufacturing of modern aircrafts, uses in advanced water filtration plants, distillation process of water, more efficient electronic instruments, more efficient batteries, textile industry, uses as manufacturer in cosmetics industry and modern defense equipment. By viewing this, we considered the numerical study of Fourier flux and buoyancy driven forces on the flow of thermal and diffusion transmission of body revolutions (Paraboloid and cone), situated in a water-logged Darcy medium by allowing the radiation, Brownian motion, time-space dependent heat source or sink, and thermopheretic. Later on, the governing system is solved via Runge–Kutta method. Properties of convoluted governing measures of the organisms on local Nusselt and Sherwood numbers along with velocity, thermal and diffusion shapes are described with the aid of graphically and tabular form. It is stimulating to declare that the non-uniform heat source or sink is highly dominated in cone form of revolution as associated to paraboloid form of flow due to more distribution of mass transfer. From this, one can draw the conclusion that wherever there are higher mass transportation phenomena, cone-shaped body of revolution can be used. It is found that the time- and space-dependent heat source or sink performs as a regulating factor of the transmission of flow phenomena.

To study the Mg-doped ZrO₂, the electronic, thermoelectric, and optical properties were characterized by first principle as well as experimental techniques. For experimental observations, the samples for pure ZrO₂ and Mg-doped ZrO₂ thin films were prepared. A noticeable difference was observed between the results of electronic, thermoelectric, and optical properties of pure and Mg-doped ZrO₂ thin films. The electronic properties extracted from simulations show that Mg-doped ZrO₂, Mg-s, Zr-d, and O-p states provide the main contributions. The electrical conductivity and Seebeck coefficient present an increasing trend with doping of Mg content. The absorption coefficient trend shows that the material becomes more absorbing with the increase in Mg content. The refractive index reduces from ∼2.2 to ∼1.8. The content of Mg carries corroborates the substantial variation in optical parameters with varying energy ranges. The comparison is carried out between the results of optical properties deduced through simulations and spectroscopic ellipsometry.

The study of modified nonlinear Schrödinger equation plays a significant role in the description of wave propagation through optical waveguides and rogue waves in ocean. The main aim of this work is to obtain solitons as well as other types of exact wave solutions to the modified nonlinear Schrödinger equation. The accurate traveling wave solutions are obtained using the $(exp(-\chi (\epsilon )))$-exponential expansion method and the modified auxiliary equation method. Consequently, soliton solutions and periodic wave solutions have been retrieved. The graphical illustrations of the results are provided for suitable values of the parameters involved in the solutions to explain the dynamical nature of the considered equation.

The electronic structure of silicene supported by monolayer of different monochalcogenide MX (GaS, GaSe, GaTe and InSe) substrates has been investigated by first principle density functional theory. By calculating the formation energies and phonons, it has been seen that silicene supported by monolayer of MX remains stable. The systems retain their almost $2D$ planner configurations with small buckling as that of the free standing silicene and also the Bader charge analysis shows that silicene hardly interacts with any of the MX substrates. The Dirac cone with a small gap ($\sim 30–50$ meV) has been observed in each of the cases. All the systems show quantum spin Hall effect and the quantum spin Hall conductivities have been estimated to be within the range $\sim 2-5\frac{\hslash }{e}$S/cm, which are larger than that of the free standing silicene. Our calculations show that even if the systems have bulk band gaps but the edge states are conducting in nature.

In the given work, compliance with the distribution law of defect vacancies formed in ZrO₂ crystal irradiated with 2MeV energy H${}^{+}$ ions at room temperature was studied (The fluxes density for the H${}^{+}$ ion was chosen to be 1017 ions/cm²). The effect of H${}^{+}$ ions with fluxes density at different temperatures (500^∘C, 600^∘C, 700^∘C, 800^∘C and 900^∘C) on W and S parameters was determined. The mechanism of formation of nanoclusters in the ZrO₂ crystal structure under the influence of H${}^{+}$ radiation, the vacancy cluster formed by 2Zr vacancies and 4O vacancies, and its location in triple spaces with hydrogen atoms were determined. 2Zr and 4 vacancies were determined by the $\tau$ values of the vacancy clusters growing under the influence of radiation and the positions of hydrogen atoms in the 1VZr, 1VO, di-VZrO triple-VZrO₂ vacancy groups.