The precise control over heteroatom cation doping is a key parameter yet poorly investigated in modulating crystal structure, reaction kinetics, and charge transport in multi-metal selenides for bifunctional electrochemical applications. Here, we systematically demonstrate the Ni doping level in cobalt manganese selenide to illustrate the concentration-dependent phase modulation, lattice modifications, and electrochemical functionality for advanced supercapacitors and the alkaline hydrogen evolution reaction. These nanostructures are synthesised via a scalable co-precipitation route followed by low temperature calcination. The structural investigations revealed that the incorporation of nickel concentration introduces controlled lattice expansion, defect regulation, and crystallinity, thereby promoting faster charge transfer and ion transport. An optimal nickel concentration of 10% maximises redox-active sites while maintaining structural stability, leading to significant enhancement in pseudocapacitive behaviour. The resulting electrode shows specific capacitance of 311 F g−1 at 0.5 A g−1, substantially surpassing the pristine cobalt manganese selenide. Apart from energy storage, dopant concentration strongly influences the hydrogen evolution activity in an alkaline electrolyte, overpotential of 197 mV at 10 mA cm−2 with Tafel slope of 107 mV dec−1. Therefore, this work establishes dopant concentration as a critical parameter in bimetal selenides and provides a unified strategy for enhancing the electrochemical behaviour.
Quantum key distribution (QKD) is increasingly evaluated as a source of cryptographic key material for optical-fiber communication services. However, a protocol that is attractive in an isolated security proof or peak-rate curve may not be the most suitable protocol-resource profile for a planned fiber link. This study presents a parameterized optical-link and receiver-constraint-aware screening framework for comparing representative QKD protocol families under a shared direct-fiber baseline. The framework evaluates BB84, Decoy-BB84, E91, B92, coherent one-way (COW), KMB09 and differential phase-shift (DPS) QKD using distance-resolved secure key rate (SKR), quantum bit error rate (QBER), photon efficiency, feasible distance, Pareto interpretation and a Robust QKD Deployment Suitability Index (R-QDSI). The study discloses the physical and protocol-specific screening assumptions, provides a MATLAB primary implementation together with an independent Python audit workflow, and reports conservative, baseline and optimistic scenario tests, finite-key penalty ablation and R-QDSI weight sensitivity. Under the disclosed baseline, COW is rate-oriented, Decoy-BB84 is error-margin-oriented, and DPS provides the strongest balanced suitability score. The results are not universal protocol rankings or field-distance claims. The contribution is a reproducible pre-deployment screening layer that can inform later hardware validation, key-management, routing, wavelength-coexistence and field-deployment studies.
The objective of this study is to experimentally analyze the thermophysical properties of 0.1% and 0.2% volume concentration (v.c.) Graphene nanofluids and their performance in cooling of Photovoltaic Panels using thermal collector system. Stability of nanofluids confirmed by Sedimentation photograph method and UV-Visible spectrometer. Thermophysical properties of nanofluids such as thermal conductivity, viscosity and density were experimentally measured over the temperature of 250C to 600C. Thermal conductivity of 0.1% and 0.2% v.c. nanofluids found to be increased with temperature as compared to base fluid. The maximum thermal conductivity of 0.824 W/m.K observed for 0.2% v.c. nanofluid at 500C. The viscosity of nanofluids linearly increased with nanoparticle loading corresponding to the temperature and shear rate. The viscosity of 0.1%v.c. and 0.2%v.c nanofluid decreased by 46.91% and 42.75% when temperature increased from 250C to 600C. The rheological analysis depicted the shear thinning behavior of nanofluids. The good degree of fit between rheological data and Cross model indicated that Cross model successfully captured all key non-Newtonian regimes. The experimental values of thermophysical properties are compared with values predicted by their respective theoretical models. The heat transfer performance of de-ionized water and nanofluids analyzed and observed maximum thermal efficiency of 91.18%, 69.46% and 28.47%, heat removal rate of 314.03 W, 231.01 W and 79.63 W for 0.2%, 0.1% v.c. nanofluid and DI water respectively by optimizing the flow rate. Maximum difference in surface temperatures of PVT and reference PV module was observed to be 10.20C, 7.20C and 40C for corresponding fluids.
Abstract Additive Manufacturing (AM), known as 3D printing, finds application in many fields since it is able to produce complex geometries with the least wastage of materials. Of all the AM processes, Fused Filament Fabrication (FFF) is the most popular because of its low cost and versatility in available materials. The mechanical properties of 3D-printed components including tensile strength, flexural strength, impact resistance, and surface finish, are highly dependent on various process parameters. It is, therefore, imperative to study and optimize these parameters for the improvement of structural integrity and functional performance of printed parts. This review analyses key process parameters affecting the mechanical properties of 3D printing. The review discusses critical factors such as layer thickness, printing speed, nozzle and bed temperature, build orientation, raster angle, infill density, and infill pattern in detail. The study presents the point of view of the influence of these parameters on mechanical performance, where examples of some recent work discussed show that certain adjustments can result in improvements in tensile strength, dimensional accuracy, and surface quality. The role of post-processing techniques like heat treatment, annealing, and chemical smoothing in enhancing the mechanical properties is also briefly discussed. Moreover, some interdynamics between the parameters are discussed to give an insight into the overall print quality concerning their interaction. The findings of this review serve as a guide for researchers, engineers, and manufacturers to optimize 3D printing parameters, enabling the production of mechanically robust and reliable components suitable for industrial applications.
Alkali metal Na-ion batteries (NIBs) present an eco-friendly and cost-effective alternative to lithium-ion batteries. However, the limited availability of high-performance anode materials continues to hinder their widespread adoption. In this study, we theoretically investigate the potential of a two-dimensional elemental monolayer of gallium, known as gallenene (Ga-100-ML), as a promising anode material for NIBs and as an electrocatalyst for the hydrogen evolution reaction (HER). The structural, dynamical, and thermal stability of Ga-100-ML is confirmed through formation and cohesive energy calculations, phonon dispersion analysis, in-plane stiffness evaluation, and ab initio molecular dynamics simulations. Electronic structure analysis reveals its metallic nature, and adsorption studies show that up to 45 Na atoms can be stably accommodated, corresponding to a high theoretical storage capacity of 961.30 mAh/g and a low diffusion barrier of 0.36 eV. Furthermore, HER activity is significantly enhanced upon Pt decoration, achieving a minimum Gibbs free energy of hydrogen adsorption of -0.12 eV. These results highlight Ga-100-ML as a promising candidate for dual applications in NIBs and catalyst for HER.
