Band 80, Heft 2

A Mach–Zehnder interference (MZI) carbon monoxide gas sensor based on tin dioxide-coated single-mode photonic crystal fiber (ESPCF) was constructed. Using the collapse fusion method, a piece of tin dioxide-coated ESPCF is embedded between the two ends of the seven-core fiber (SCF) to form an SCF-ESPCF-SCF optic-fiber sensor with an MZI sensing structure. To examine the properties of the sensing layer, including its crystalline structure, elemental makeup, and surface appearance, we utilized XRD for diffraction studies, XPS for compositional analysis, and SEM for morphology imaging. The outcomes confirm the successful synthesis of the tin dioxide sensing material, with the formation of a uniform morphology, coating approximately 1.5 μm in thickness on the fiber’s surface. Notably, the sensor exhibits a sensitivity to carbon monoxide of 0.01696 dB/ppm, with activation and reset durations being 60 s and 72 s, correspondingly. The sensor demonstrates high sensitivity, strong selectivity, a favorable linear response, and stability, rendering it highly efficacious for the environmental monitoring of toxic carbon monoxide gas.

We construct a new class of N -dimensional Lie algebras and apply them to integrable systems. In this paper, we obtain a nonisospectral KdV integrable hierarchy by introducing a nonisospectral problem. Then, a coupled nonisospectral KdV hierarchy is deduced by means of the corresponding higher-dimensional loop algebra. It follows that the K symmetries, τ symmetries, and their Lie algebra of the coupled nonisospectral KdV hierarchy are investigated. The bi-Hamiltonian structures of the both resulting hierarchies are derived by using the trace identity. Finally, we derive a multicomponent nonisospectral KdV hierarchy related to the N -dimensional loop algebra, which generalizes the coupled results to an arbitrary number of components.

In the context of superluminal physics, this article explores the latest advancements including the primary theoretical developments in special and general theory of relativity (STR & GTR). We have reviewed the significant strides made so far and addressed the difficulties encountered with purported interpretation. The proposed or derived transformation factors for superluminal particles can be categorized into two categories, i.e. , imaginary and real transformation factors. The transformation relations between the two classes of frames have been scrutinized using the metric expressions. The velocity addition and transformation relations of mass, momentum, and energy between the frames for superluminal particles have also been analyzed. The analyses using Klein–Gordon equation, which is the relativistic energy-momentum equation, for tachyons have been performed. In brane–antibrane system, universality of tachyon potential via tachyon condensation was articulated. The unstable brane system, by virtue of tachyon condensation, promotes the cosmological evidence. In advancing the pace of development of cosmological research, superluminal physics is one of the most astonishing fields. Approaching toward GTR for cosmological application, tachyons have been scrutinized in Schwarzschild, Kerr–Newman, and FLRW metric spaces. Tachyons in Friedman universe correspond to different applications, like measurements of Hubble’s constant, theory of big-bang, expansion of universe. Some of the experimental evidences provided by GRS 1915+105, SN 1987A, GRB 030329, GW 170817, etc., for the existence of tachyons have also been analyzed. Einstein’s postulate for the constancy of the speed of light has been commented on for the highest approachable speed observed by the particular observer.

This research has focused on studying the electro-magneto-hydrodynamic (EMHD) nanofluid flow over a stretched cylinder in the presence of electro-osmotic force and mixed convection. This inquiry shows a novel approach through the use of thermophoresis and Brownian motion and nanofluid is comprised of water and copper nanoparticles. Similarity transformations simplified the mathematical model and produced nonlinear ordinary differential equations with suitable boundary conditions, which the MAPLE-21 software numerically solved using the RK-4 shooting criteria. Tables and graphs have been used to illustrate the impact of the key flow factors on Electric potential profiles, velocity profiles, temperature outlines, and concentration distribution. Following the physical deliveries, we have calculated the Sherwood number, Nusselt number, and skin friction. The electro-osmotic parameter diminishes the electric potential profiles and a dual effect occurs for the curvature parameter. The Nusselt number declined by 5.91 % for the electro-osmotic parameter but the Sherwood number enhanced by 30.7 % at a rate. The practical applications of this model shed light on thermal management in electronics and nuclear reactors, plasma physics, various chemical processes, filtration, separation, and fuel cells, as well as the manipulation of biological fluids in lubrication or medical devices.

These days, researchers are digging deep into the Zintl family of chemicals to uncover its many useful physical characteristics. Using a first-principles approach, this study investigates novel Zintl family XZn 2 Si 2 (X = Ca, Sr, Ba) compounds for their different properties. The structural and electrical properties are represented by PBE-GGA and TB-mBJ potentials, respectively. The equilibrium structural parameters, which change with ionic radii, are obtained by optimization. The computations of the elastic constants confirmed the mechanical stability of the compounds. Elastic moduli, melting temperature, hardness, Debye temperature and acoustic properties are widely described. The compounds’ elastic anisotropy also discussed and extensively. The three compounds’ metallic origin was disclosed by their band structures. Chemicals exhibiting a high degree of valence band p-d hybridization. The compounds exhibit a combination of ionic and covalent bonding. In order to study the interaction between light and matter, the optical reflectivity, optical conductivity, and absorption coefficient are computed. In contrast to other compounds, CaZn 2 Si 2 exhibits n -type transport. Among the compounds, CaZn 2 Si 2 has the best figure of merit and may find use in thermoelectric devices.