In this work, we synthesized gadolinium (Gd3+) and aluminum (Al3+) co-doped calcium oxide (CaO) nanoparticles using a green sol-gel route with guava leaf extract as the capping agent. This synergistic co-doping strategy suppressed thermal-induced grain growth and improved the structural stability of pristine CaO nanoparticles. X-ray diffraction (XRD) analysis confirmed that the samples maintained a single-phase cubic rock-salt framework. However, significant lattice strain was induced due to the ionic size mismatch between the dopant ions and the Ca2+ host lattice. This mismatch compressed the average crystallite size from 25.40 nm to 13.46 nm, while increasing both lattice microstrain and X-ray density. Scanning electron microscopy (SEM) revealed a morphological transformation from large spherical particles to clustered flake-like nanostructures with reduced particle size. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) confirmed the successful incorporation of Gd and Al into the CaO lattice, the Ca2+ oxidation state, and the presence of lattice oxygen and oxygen-vacancy-related surface species. The optical results showed a progressive decrease in the optical band gap from 3.66 eV for pristine CaO to 3.46 eV for the sample containing 3 mol% Gd3+/Al3+. This band-gap narrowing is attributed to dopant-induced modifications of the electronic structure and defect-related states associated with incorporating Gd3+ and Al3+ into the CaO matrix. Thermogravimetric and differential thermal analyses (TGA/DTA) showed a clear three-stage mass loss. The residual plant organics burned away completely below 350°C and intermediate carbonate phases decomposed between 600°C and 750°C, leaving a phase-stable profile above 800°C. These composition-dependent structural, optical, and thermal modifications demonstrate the potential of the co-doped CaO nanoparticles for applications requiring tunable physicochemical properties.
In this work, amorphous germanium thin films were coated with yttrium (Y), ytterbium (Yb), and lead (Pb) nanosheets to function as optical layers suitable for visible and ultraviolet (UV) optical communications. It was observed that Y and Pb coatings reduced the average surface roughness by 8.5% and 22.6%, respectively. In addition to enabling tailoring of optical transmittance and reflectance, Pb-, Yb-, and Y-nanosheet coatings increased the optical band gap of Ge films from 0.89 eV to 0.93 eV, 1.03 eV, and 1.10 eV, respectively. As an optical layer, Y increased the real part of the dielectric constant and decreased the optical conductivity, terahertz cutoff frequency, free-electron density, and plasmon frequency. In contrast, Yb and Pb increased these parameters substantially. Drude–Lorentz modeling of the imaginary part of the dielectric-function spectra indicates that Ge, which is an effective optical layer, can be rendered more suitable for visible and UV optical communication by nanosheet coating, as evidenced by the enhanced terahertz cutoff frequency of 174/140 THz and 89/78 THz and plasmon frequencies of 7.15/15.54 GHz and 7.15/16.69 GHz for green (2.70 eV) and UV (3.60 eV) active oscillators when Ge was coated with Yb and Pb, respectively. Owing to the improved optical conductivity, increased terahertz cutoff frequency, and enhanced electron drift mobility induced by metal-nanosheet coating, these Ge-based optical layers are promising candidates for wireless visible- and UV-band optical communication technologies.
Radioactive waste management in a safe, easy, and cost-effective manner is a critical imperative for the global environment. Removal of radioactive strontium (90Sr) from contaminated water, such as seawater (high-salinity matrices), with high efficiency and selectivity remains a critical challenge. Here, we report a one-pot sol-solvothermal synthesis of a titania-carbon composite monolith (TCCM) based on in situ carbonization. The TCCM exhibited many advantages, including a high specific surface area (138.2 m2 g−1) and a narrow pore size distribution (6.2 nm). The results indicated that this batch adsorption study showed a maximum Sr2+ adsorption capacity of 77.3 mg g−1 at pH 6–9. The fabricated material demonstrates high selectivity, removing 86% of Sr2+ (9.5 mg g−1) from authentic Red Sea seawater. Kinetics follow the pseudo-second-order model (R2 = 0.992), and the Langmuir isotherm confirms monolayer chemisorption. Furthermore, the TCCM retains 89.2% of its initial capacity after six regeneration cycles, outperforming many reported composites. Thus, TCCM is a durable, highly selective, and reusable strontium sorbent in complex aqueous environments.
An approach to nanotechnology that is both practical and environmentally friendly is one that involves the synthesis of nanoparticles using some of the principles underlying green chemistry. The agro waste mediated synthesis of iron oxide nanoparticles (Fe3O4 NPs) was performed by utilizing the peel extract of Artocarpus heterophyllus, also known as jackfruit. Functional group identification was done through Fourier transform infrared spectroscopy (FTIR), by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray (EDX) instruments were used to characterize the morphological textures and composition of Fe3O4 NPs that were synthesized using jackfruit peel extract (biosynthesized Fe3O4NPs). Fe3O4 NPs demonstrated most effective antibacterial activity at concentrations ranging from 50 to 100 μg/mL and cytotoxicity against the A549 cancer cell line (IC50 = 18.25 μg/mL), and this was performed by trypan blue exclusion assay. In addition, the Fe3O4 NPs displayed anti-inflammatory capabilities with an IC50 value of 9.17 μg/mL, demonstrating their potential as an effective anti-inflammatory agent in human red blood cells. The results of this study may pave the way for the creation of new avenues for the development of ecologically friendly and economical advancements for the synthesis of Fe3O4 NPs that may be employed in a variety of applications, including the biomedical and pharmaceutical areas.
An entry-wise combinatorial formula for the inverse of a modified Laplacian matrix of a connected signed graph G is provided. The approach employs the Moore–Penrose inverse of the full-rank matrix associated with G. Several properties of the entries of this inverse matrix are also derived, some of which reflect structural properties of the signed graph, including whether it is balanced.
