Gomal University

Modeling of novel materials in response to overcome the energy crises in the form of clean and recyclable resources is the requirement of the technological era. We utilized Density Functional Theory (DFT) based simulations in order to model monolayers OMoGeN2 and OWGeN2 and their optimized structural parameters were calculated. The stability of each material was confirmed from their per atom cohesive energies. The dynamical stabilities for the under-study materials were confirmed through phonon spectra having no soft modes and for thermal stability. Ab initio molecular dynamics (AIMD) computations were also performed at 300, 600 and 900 K. The electronic properties were investigated by computing their band structures and density of states. Indirect band gap semiconducting nature is observed in both monolayers, where the transition metals are dominant in contribution to the valence and conduction bands. Strain induced variation in band gap values with unaltered band nature is observed and the band gap range spans from 0.05 eV to 1.97 eV. For optoelectronic applications, real and imaginary part of the dielectric function are computed in free strain and strained environment. The absorption coefficient, refractive index, and extinction coefficient are also computed using the complex dielectric function. Boltzmann's transport theory is used to compute the power factor and ZT to quantify the thermoelectric efficiency of these layers. Transport calculations for the two compounds show dependence on strain; OMoGeN2 and OWGeN2 possess highly tunable thermoelectric properties with values of (ZT) approaching unity in the large range of chemical potentials.

Developing sustainable and reliable energy storage systems is a primary challenge in the modern quest for uninterruptible electricity. Supercapacitors have become a leading solution because of their rapid charge–discharge rates, exceptional power density, and long-term stability. A key factor in their efficiency is the electrode design; in this research, a perovskite YbFeO3 and reduced graphene oxide (rGO) nanohybrid was synthesized through a facile hydrothermal method. Physical analysis revealed a tetragonal morphology of YbFeO3 successfully integrated onto rGO sheets, providing a significant Brunauer–Emmett–Teller (BET) surface area of 157 m2 g−1. When assessed electrochemically in a 3 M KOH electrolyte, the YbFeO3/rGO nanohybrid exhibited superior performance due to the synergistic effects between metal oxide and carbonaceous framework. At a current density of 1 A g−1, the electrode achieved a high specific capacitance (Cs) of 981 F g−1, specific energy of 26 Wh kg−1, and specific power of 112 W kg−1. Furthermore, the YbFeO3/rGO demonstrated excellent electronic conductivity, with series resistance (Rs) of 1.18 Ω, and maintained robust structural integrity over 5000 cycles. These exceptional properties, combined with its cost-effectiveness and durability, establish the YbFeO3/rGO nanocomposite as a highly capable candidate for next-generation supercapacitor applications.

This research indicates the fabrication of a nanocomposite consisting of reduced graphene oxide (rGO) and copper chromite (CuCr2O4) by hydrothermal process. The morphology and structure of CuCr2O4/rGO composite were studied using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). For electrochemical studies, paracetamol (PAR) detection was performed by a glassy carbon electrode (GCE) modified with CuCr2O4/rGO, leveraging the synergistic properties of both components. Cyclic voltammetry (CV) and square wave Voltammetry (SWV) measurements revealed high oxidation peaks for PAR, shows the sensor’s effectiveness. The suggested electrode demonstrates outstanding electrochemical activity for PAR. Under ideal conditions, a limit of detection (LOD) of 0.19 µM and 0.049 µM was obtained within the dynamic range of 5–30 µM and 2–15 µM for PAR. This electrode exhibited exceptional stability and sensitivity, rendering it suitable for the investigation of diverse actual pharmaceutical samples.

This paper presents a novel dual-band cylindrical dielectric resonator antenna featuring a distinctive cross-ring structure that enables circular polarization (CP) across two critical frequency bands. The proposed antenna operates efficiently in both the 8-16 GHz microwave band and the 24-30 GHz millimeter-wave band, making it particularly suitable for ultra-wideband (UWB) and emerging 6G applications. Examination of the $S_{11}$ parameters reveals excellent impedance matching below $-10$ dB, yielding an impressive bandwidth of approximately 8 GHz (64.26%) in the lower band and approximately 6 GHz (23.72%) in the upper band. The antenna achieves stable CP through degenerate orthogonal modes, i.e., $\mathrm{TM}<^>{x}_{11\delta}$ and $\mathrm{TM}<^>{y}_{11\delta}$, in the cylindrical dielectric resonator, with 3-dB axial-ratio bandwidth extending across both operating bands (approximately 8 GHz in the UWB band, representing 54.91% bandwidth, and approximately 6 GHz in the mmWave band, representing 20.12% bandwidth). The antenna delivers consistent gain performance, averaging 7.0 dBi in the UWB band and 6.5 dBic in the mmWave band. The novelty of this design lies in its elegant cross-ring feeding structure that simultaneously enables dual-band operation, excellent CP characteristics, and high radiation efficiency in a compact form factor. Simulation results closely align with measured data, confirming the antenna's suitability for next-generation wireless communication systems.

The primary objective of this research work is to establish strong coupled fixed point results in multiplicative metric spaces using maximum and product types of cyclic coupled contractions. In support of our main results, we present trivial and nontrivial illustrative examples within the space. Furthermore, an application of the Lebesgue integral equation is provided in aid of the proposed work on multiplicative metric spaces. It has the potential to be extended in many directions in the context of different types of metric spaces, with different types of contractive conditions for nonlinear mappings, and with the application of different types of integral equations.