International Journal of Modern Physics B

The present flow problem analyzes the impact of radiative heat and mass transfer with inclined magnetic field on thermal exchange and entropy production of two immiscible nature of electrically conducting couple stress fluid in a static porous saturated conduit. In this model, the lower and upper porous regions of the rectangular channel are occupied by two different types of couple stress fluids. The static horizontal parallel plates of the porous duct are completely isothermal and the flow of immiscible fluid through the porous duct develops because of a constant pressure gradient at the entry zone of the duct. The Brinkman model is utilized in the modeling of fluid flow through porous saturated domain and Rosseland’s approximation is utilized to compute the radiative thermal exchange effect on nonmiscible couple stress fluid. In this work, authors have analyzed the effect of various thermo-physical parameters such as the Hartmann number (Ha), permeability parameter (Da), Schmidt number (Sc), Soret number (Sr) and couple stress parameter ($s_i,i=1,2$) on the entropy generation characteristics, Bejan number distribution, thermal behavior, concentration distribution and flow characteristics of immiscible couple stress fluid which passes through the porous channel. The parameters Ha, Da, $s_i$, Sc, Sr correspond to magnetic field effect, permeability of porous media, couple stress, mass diffusion and thermal diffusion, respectively. The most significant findings of this research work are as follows:

• •In a porous saturated channel, the immiscible couple stress fluid velocity, entropy production number and thermal profile get enhanced on increasing the couple stress parameter.
• •On increasing the Hartmann number and decreasing the permeability of porous region, the thermal properties and entropy production number both decrease.
• •The couple stress fluid’s concentration field and Bejan number distribution get decreased on enhancing Soret number Sr and Schmidt number Sc.
• •The entropy generation near the wall of the channel rapidly increases on increasing the Schmidt number and Soret number.

The emerging finding of this research work exhibits excellent agreement with previously published work. This research work can be utilized in food processing, petroleum products and chemical process.

This paper proposes abundant accurate wave solutions that represent the plasma wave propagation based on crystal lattice theory and physicochemical characterization. The Gilson–Pickering (${𝒢}{𝒫}$) model is analytically and numerically solved by two recent techniques. This model is a basic unidirectional wave propagation model that describes the prorogation of waves in crystal lattice theory and plasma physics. The investigated model has a deep connection with some nonlinear evolution equations under specific values of its parameters, such as the Fuchssteiner–Fokas–Camassa–Holm (${ℱ}{ℱ}{𝒞}{\mathscr{H}}$) equation, the Rosenau–Hyman (${ℛ}{\mathscr{H}}$) equation, and the Fornberg–Whitham (${ℱ}{𝒲}$) equation. The Sardar sub-equation and He’s variational iteration techniques are employed to construct novel and accurate solitary wave solutions of the handled model. The obtained solutions are explained through some distinct graphs in contour, three-, two-dimensional. The research value is explained by comparing our results with some recently published studies. The employed methods show their simple, direct, effectiveness and their ability for handling many nonlinear evolution equations.

Unidirectional reflectionlessness is investigated in a waveguide quantum electrodynamics system that consists of a cavity and a $\mathrm{\Lambda }$-type three-level quantum dot coupled to a one-dimensional plasmonic waveguide. Analytical expressions of transmission and reflection coefficients are derived and discussed for both resonant and off-resonant couplings. By appropriately modulating the coupling strength, phase shift and Rabi frequency, unidirectional reflectionlessness is observed at the exceptional points (EPs). And unidirectional coherent perfect absorption is exhibited at the vicinity of the EP. These results might find applications in designing quantum devices of photons, such as optical switches and single-photon transistors.

In recent years, vanadium pentoxide (V₂O₅) nanoparticles (NPs) have attracted considerable interest due to their potential medicinal applications, including cancer therapy, antibiotic resistance and antibacterial activity. Manufacturing V₂O₅ NPs is a crucial step in developing these applications, and laser ablation in solution has proven to be a particularly successful technique. Following fabrication, colloidal solutions were analyzed using ultraviolet–visible (UV–Vis) absorption spectra, Fourier transform infrared (FTIR) spectrum, transmission electron microscopy (TEM) and X-ray diffraction (XRD). In this work, XRD study revealed that the produced NPs had an orthorhombic phase. Based on the laser energy, nanosized vanadium pentoxide particles were created by laser irradiating a vanadium bulk submerged in a double deionized water (DDW), resulting in spherical particles with average sizes ranging from 15.4 to 33.8nm, as shown by TEM micrographs. Conforming to the quantum size concept, the bandgap energy of V₂O₅ NPs is higher than that of bulk V₂O₅ due to the decrease in particle size. This study examined the effectiveness of V₂O₅ NPs against pathogenic bacterial strains Staphylococcus aureus as Gram’s positive bacteria and Escherichia coli as negative Gram’s bacteria. Then, we evaluated anticancer activity of V₂O₅ NPs against a breast cancer cell line (MCF-7 cells) using MTT assay. The results reveal that the activity of prepared V₂O₅ NPs against S. aureus is greater than that of E. coli. The findings suggest that prepared NPs can act as an anti-proliferative agent against MCF-7 cells. Subsequently, the produced NPs might be exploited as a future strategy for other biomedical applications.

The structural dependence of nonlinear optical properties associated with ADP-doped PVA/PVP polymer composites is discussed in this work. Polymer composites are fabricated using the solution casting method. X-ray diffraction (XRD) was used to perform structural analysis on these samples whose average crystallite size increases with an increase in dopant concentration. Results from UV–Vis–NIR spectra show that the samples are transparent in the IR region. The Z-scan technique was established by following the method described by Sheik-Bahae et al. The shape of the open aperture plot suggests that the samples exhibit two-photon absorption. The NLO properties such as nonlinear absorption coefficient ($\beta )$, two-photon absorption cross-section (${\sigma }_2)$ and the imaginary part of third-order nonlinear susceptibility $({\chi }^{(3)})$ were investigated at 1064 nm and these values were found to be in the order of $\sim {10}^{-7}$W/cm, $\sim {10}^{-20}$cm⁴/GW and $\sim {10}^{-14}$esu, respectively. The open aperture Z-scan method yielded optical limiting data, from which the optical limiting threshold was calculated to be in the order of $\sim {10}^{13}$W/m². Functional data analysis uses a suitable basis representation to assess the functional correlation between global and local variables.

In this paper, we investigate a (3+1)-dimensional integrable fourth-order nonlinear equation that can model both the right- and left-going waves in a fluid. Based on the Hirota method, we derive three sets of the bilinear auto-Bäcklund transformations along with some analytic solutions. Through the extended homoclinic test approach, we obtain some breather solutions. We find that the breather propagates steadily along a straight line, with one hole and one peak in each period. Graphical investigation indicates that the coefficients in that equation affect the location and shape of the breather. Moreover, we construct some mixed lump–kink solutions. Fusion and fission between a lump wave and a kink soliton are analyzed graphically. The solutions addressed in this paper may be applied to mimic some complex waves in fluids.

Riga plate is known to create a crossing electric and magnetic field to generate a wall-parallel Lorentz force. The significance of Casson nanofluid flow past a Riga plate is observed in the sphere of engineering, such as polymer extrusion, food manufacturing, plastic films, oil reserves and geothermal manufacturing. Researchers are interested in this model because of its potential use in biological rheological models. As Casson nanofluid flows are of great interest, this study aims to investigate the three-dimensional magnetohydrodynamics (MHD) flow with heat and mass transport of Casson nanofluid over a flat Riga plate. As a novelty, this study also includes the effectiveness of wall velocity slip, activation energy, nonlinear radiation, and temperature and space-dependent heat source/sink. Suitable similarity transformations have been employed to generate the dimensionless ordinary differential equations (ODEs) from the partial differential equations (PDEs) regulating the fluid flow problem. The transformed nonlinear boundary value problem is then solved numerically using the in-built routine “bvp4c” in MATLAB. The visual demonstrations are provided for the effects of various significant physical factors on the flow, heat and mass distributions. On the other hand, wall shear stress and rates of heat and mass transport at the surface are measured and displayed numerically in tabular form. The findings indicate that the fluid velocity in both directions slows as the velocity slip parameter increases. However, the velocity profile is escalated with the boost of modified Hartmann number. An increase in heat source parameters leads to decrease the heat transmission rate at the wall. The higher values of the radiation parameter result in a better wall heat transmission rate. Further, the rate of mass transport drops when the activation energy parameter is hiked.

Because of accelerated demands of advanced technologies like power station, chemical production and microelectronics, it necessitates the need of novel type of fluids with more heat transfer capability. Due to synergistic effect, ternary composite nanofluids (TCNFs) ensure better thermophysical and Rheology properties thereby acting as better suitable heat transfer fluid in wire coating, metal spinning, aerodynamics, medicine and engineering industries, etc. In view of such relevance, flow and heat transfer aspects of TCNF MWCNT + Al₂O₃ + TiO₂ + water induced by linear and nonlinear slips over arbitrarily inclined moving thin needle are investigated in this study. Thompson and Troian nonlinear slip model is modified by developing it in polar coordinates. Quadratic thermal radiation phenomenon is adopted. Fourth-order Runge–Kutta method is used to obtain requisite numerical solution. Major outcomes indicate that fluid velocity of TCNF whittles down with amplification of magnetic parameter due to the flow induced by either linear or nonlinear slips. Lower value of Reynolds number favoring linear slip leads to effective intensification of nondimensional temperature distributions. Surface viscous drag and heat transfer rate get ameliorated with growth in size of thin needle under the influence of both linear and nonlinear slips.

We study the frictional drag phenomenon in a double-layer system made of two parallel gapped graphene layers by calculating the Coulomb drag resistivity. The random-phase approximation is employed to determine the polarizability functions of layers and the frequency-dependent dielectric function of the structure. Our computations illustrate that the Coulomb drag resistivity in double-layer gapped graphene systems show some interesting different features, compared to that in other double-layer ones. Coulomb drag resistivity in the system steadily increases as temperature increases but quickly decreases with the increase in interlayer distance. With small interlayer separations, the drag resistivity behaves as a smoothly increasing function of the bandgap. Nevertheless, with sufficiently large separations, the Coulomb drag resistivity increases with small bandgaps but decreases with larger ones. We observe that a finite bandgap has remarkable contributions to the frictional drag phenomenon, therefore it is necessary to take into account this factor in calculations to make better agreements with experimental works.

In this work, calcium silicate nanophosphors (CaSiO₃) doped with Sm${}^{3+}$ ions were prepared at $900^{\circ }$C by a simple solution combustion synthesis technique. The particle size, functional groups and morphology of the prepared phosphors were identified by X-Ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) techniques. The monoclinic phase of the nanophosphors was confirmed by X-ray diffraction studies. The effective excitation of the nanophosphors near the UV region and their yellow emission were confirmed by photoluminescence studies.

An electrically conducting time-dependent flow of water-based nanofluid comprised of Copper and Titanium oxide over a stationary plate embedding with a porous matrix is analyzed in this study. The novelty arises due to the interaction of both the thermal radiation as well as the radiation absorption that affect the heat transport phenomenon. In the single-phase flow, both the variation of particle concentration and the solutal concentration for the inclusion of chemical reaction are taken care of. Also, the influence of the free convection phenomena is explained significantly. The transformed dimensionless system of the governing equations is handled analytically by using the Laplace Transform method. The behavior of the characterizing parameters involved in the governing equations is presented via graphs and the simulation of the numerical results of the rate coefficients like shear rate and rate of heat and solutal transfer is deployed through the table. However, the physical significance of these parameters is deliberated briefly. Finally, the important outcomes are higher heavier species because of lesser solutal diffusivity which attenuates the fluid concentration throughout the domain. Further, radiation absorption causes a significant boost in the nanofluid temperature distribution.

In this paper, theoretical investigations of structural, elastic and thermal properties of Zn₃P₂ material were done using Quantum ESPRESSO code based on density functional theory. The generalized gradient approximation (GGA) exchange correlation-functional helped to model the atomic interaction. First, the structural optimization procedure was carried out, and hence, the optimized structural parameters were utilized to obtain six independent elastic constants $C_{11},C_{12},C_{13},C_{33},C_{44}$, and $C_{66}$ for the Zn₃P₂ tetragonal structure. Accordingly, these elastic constants were used to determine the elastic moduli such as the Bulk modulus, Young’s modulus, and shear modulus, as well as other mechanical parameters such as Pugh’s ratio, Poisson’s ratio, anisotropic ratio, sound velocities and Debye temperature. Calculations of thermodynamic properties such as vibrational energies, vibrational free energies, and fixed volume heat capacities, were performed within the implementation of the Thermo_pw code. Elastic calculations confirmed that this compound is characterized by mechanical stability at zero pressure and 0K temperature, ionic bonding, a high degree of anisotropy, and typical ductility. An observable increase in Debye vibrational energies, entropies and constant volume heat capacities of this compound with increasing temperature was detected throughout the thermodynamic calculations, unlike vibrational free energy which revealed a pronounced decrease as temperature increased.

The hybrid nanofluid is the modified class of nanomaterials with impressive thermal impact and preserves significant applications in extrusion systems, thermal management systems, engineering processes, cooling and heating materials and many more. The aim of this research is to communicate the thermal enhancement of water (H₂O) and sodium alginate (C₆H₉NaO₇) base fluids with interaction of hybrid nanofluids. The Casson fluid model is used to endorse the properties of such base liquids. The titanium dioxide and silver nanoparticles incorporate the thermal impact of hybrid nanofluid properties. The fractional simulations are performed by using the Caputo–Fabrizio (CF) time-fractional derivatives. The integration of problem is computed via Laplace technique. It is observed that the velocity profile enhanced the Grashof number. The increasing observations for Nusselt number and wall shear force due to fractional parameters are obtained.

This study examines different fluid flow through an elaborated plate. In the modeling of the physical phenomena under investigation, the impacts of viscous dissipation, activation energy and chemical reaction are considered. Also, the heat transport phenomena are explained by the variable thermal conductivity theory. By using the right transformations, the flow-generating PDEs are converted into nonlinear ordinary differential equations. The parameters’ impacts on the velocity, temperature and mass fields are analyzed in detail. The modeled problem is graphically handled in MATLAB using the numerical technique (BVP4c). Graphical representations of the important factors affecting temperature and velocity fields are illustrated through graphs. The findings disclose that the effectiveness of the velocity field is determined by the changing values of the magnetic parameter. The Prandtl values are decreased, the temperature profile becomes more pronounced.

The structural and magnetic analysis of the YFeSb${}_{1.2}$ compound synthesized by the solid-state reaction method was observed. At room temperature, the compound exhibits the ThCr₂Si₂-type structure with the space group of $I4∕mm$. Low-field DC magnetic susceptibility property of the YFeSb${}_{1.2}$ compound has been examined. An obvious oscillation of the remanent magnetization, $M_{\mathrm{\text{rem}}}(T)$ with temperature was observed. The YFeSb${}_{1.2}$ compound exhibits large irreversibility at low fields below the coercivity fields due to freezing spins at low temperatures. At higher temperatures, the susceptibility obeys perfectly to modified Curie–Weiss behavior. Each magnetic ion on a microscopic scale and each magnetic cluster on a nanoscale experience reveal a local random anisotropy.