This study investigates the structural, optical, dielectric, and electromagnetic absorption properties of spinel‐structured Mg–ZnAl2O4 synthesized through a sol–gel technique. The structural analysis confirmed the presence of various phases, including MgO, ZnO, ZnAl2O4, and MgAl2O4, with an average crystallite size of approximately 88 nm. The material demonstrated a reflection loss of −71 dB at 14.02 GHz, indicating its potential for effective microwave absorption, with an effective absorption bandwidth of 3.66 GHz at a thickness of 5 mm. The optical band gap was determined to be 3.19 eV, lower than that of ZnAl2O4 and MgAl2O4, suggesting enhanced microwave absorption capabilities. Dielectric characterization revealed a range of dielectric constants from 3.09 to 6.31 across the frequency range of 8 to 18 GHz. These findings highlight the promising application of Mg–ZnAl2O4 in microwave absorption technologies due to its favorable structural and electromagnetic properties.

Microring resonators (MRRs) are the important devices for the development of silicon‐based optoelectronic integrated chips. Their composition of optical modules, such as optical modulators, switches, and optical logic gates, have greatly contributed to the development of the silicon‐based optoelectronics. However, due to the large radius of MRRs and the weak optical interaction of the silicon material itself, how to further improve integration and reduce power consumption is a great challenge. Combining graphene, which has many unique properties, with silicon‐based MRRs provides a good solution. Therefore, based on the interaction principle of graphene and light and the transmission principle of all‐pass silicon‐based MRRs, this article proposes for the first time a one‐bit optical numerical comparator based on MRRs, whose structure consists of four silicon‐based MRRs with a radius of 1.8 μm covering a single layer of graphene. The logic function of the one‐bit optical numerical comparator is realized by adjusting the different chemical potentials of the graphene. Simulation results shows that, with a TE mode light source at 1555.21 nm, the proposed optical numerical comparator obtains a minimum extinction ratio of 19.7 dB and a contrast ratio of 19.7 dB. Compared with the previously reported optical numerical comparators based on silicon‐based MRRs or ring resonators, the proposed optical numerical comparator has many advantages, such as high extinction ratio, high contrast ratio, compact structure, and high stability. It is beneficial to the development of silicon‐based photonic integrated devices.

Graphene is a single layer of carbon atoms arranged in a hexagonal lattice structure, forming a two‐dimensional (2D) material with exceptional mechanical, electrical, and thermal properties. Graphene has emerged as one of the most promising nanomaterials because of its unique combination of exceptional properties: the thinnest and the strongest materials, an excellent conductor of electricity, and optically transparent as well. This article provides an overview of graphene materials regarding its basic structure, preparation methods, and unique properties. The four commonly used methods for preparing graphene are compared, and the advantages and disadvantages of each are expounded and briefly summarized. And the basic physical properties of graphene materials obtained by each method, namely, in mechanics, electricity, thermal, and optics, were elaborated in detail, and the related applications of graphene prospects are further discussed.

Electrospinning is a promising technique for enabling the manipulation of the structural properties of nano‐ or microfibrous mats by altering electrospinning parameters. In this paper, it is aimed to examine the morphological variations of electrospun mats fabricated by combinations of different collector types and feeding units. In horizontal electrospinning setup, PVA polymer solutions are transformed to polymer jets by the help of needle‐based feedings with single‐ and multinozzles. Electrospun fibers are deposited on four different collector types with identical collector‐nozzle distance, feeding rate, applied voltage, and environmental conditions. It is concluded that the coarsest nanofibers are fabricated by multineedle/disc collector combination and the disc collector causes flat nanofiber handling with multineedle feeding but not with single needle feeding. On plate collector, thicker electrospun mats are obtained whichever feeding type is used. Average pore sizes on mats are found higher in multineedle feeding, especially with deposition between rods of birdcage collector. Changing the feeding type from multineedle to single needle causes to manufacture of electrospun mats with a narrower surface area and an increase is observed in packing density, basis weight and % porosity but a decrease in pore size and mat thickness with this manipulation. Nanosized but flattened electrospun fibers are handled by multineedle/disc collector and two distinct compositions are incorporated by deposition of nanofibers on birdcage collector.

Gold nanoparticles (AuNPs) have been targeted as novel contrast agent for computerized tomography (CT). However, AuNPs suffer from low‐contrast factor in the X‐ray regime. Functionalization of AuNPs with folic acid or sugar‐based molecules to induce selective uptake have displayed contrast enhancement with improved image brightness and CT signal intensity. However, it was not clear what the basic mechanism for the contrast enhancement was and whether it was related to the uptake enhancement or to a fundamental electromagnetic interaction effect. In this work, we conducted near‐field Mie as well as finite‐difference time‐domain (FDTD) field distribution of the scattering to discern the effect of a thin dielectric coating layer on the contrast functionality of AuNPs. Our results show that upon the incorporation of the dielectric shell (thin film or nanoparticle layer), the cross section of X‐ray scattering is enhanced, with silicon being more effective than silica coating, with multiresonance spectral response. The directionality and range and strength of the near field increase for silicon coating (high electron density or high k material in the visible). The effect may be understood in terms of several features. Even though the refractive indices of all materials in the X‐ray regime are ∼ 1.0, the wavelength dependence of their approach may exhibit sizeable differences The enhancement is understood in terms of high densities of polarization charge especially in silicon, which allows multipole resonances. The multiplicity of resonances leads to enhanced scattering and directionality (angular distribution) with reduced range. A silicon‐coating layer on AuNP may not only alleviate the contrast limitation, but it may afford synergistic integration of luminescence and scattering functionalities in the visible and X‐ray regimes.

The current study was used to achieved the green synthesis of pure with different percentages of zirconium‐doped cerium oxide nanoparticles (Zr‐doped CeO2 NPs) using an aqueous plant extract of Sanvitalia procumbens. The synthesis of pure NPs was achieved by mixing 30 mL of Ce (NO3)3·6H2O into 10 mL of plant extract and then adding ZrO (NO3)2. xH2O into a reaction mixture to synthesize Zr‐doped CeO2 NPs with the variation of x (x = 5%, 10%, and 15%). The phytochemicals present in Sanvitalia procumbens plant extract function as stabilizing and reducing agent which may have ability to synthesize pure and Zr‐doped CeO2 NPs. The synthesized NPs were characterized by different analytical techniques, such as UV‐visible (UV‐Vis), scanning electron microscopy (SEM), energy dispersive X‐ray (EDX), Fourier transform infrared spectroscopy (FT‐IR), and powder X‐ray diffraction (PXRD). The UV‐Vis spectroscopy revealed that zirconium (Zr) was well doped in CeO2 NPs with a band gap energy of 4.07–4.56 eV. The SEM images demonstrate the irregular morphology with an average particle size range of 26.72, 24.37, 21.24, and 19.12 nm for pure, 5%, 10%, and 15% Zr‐doped CeO2 NPs, respectively. The fundamental elemental composition of Zr‐doped CeO2 NPs was ascertained by EDX analysis, whereas the PXRD patterns support the crystalline nature of NPs. Furthermore, the synthesized pure and Zr‐doped CeO2 NPs were used to analyze the antiplatelet activity that showed dose‐dependent antiplatelet potentials. The results revealed that 15% Zr‐doped CeO2 NPs showed maximum antiplatelet activity that was 84.24 s at concentrations of 100 μg/mL. Moreover, the IMR32 cell line was also studied to demonstrate the cytotoxicity of pure and Zr‐doped CeO2 NPs. Accordingly, Zr‐doped CeO2 NPs exhibits higher cytotoxic effects against brain cancer in contrast to undoped CeO2 NPs. Thus, the obtained results suggest the potential use of Zr‐doped CeO2 NPs as an industrial application such as in the development of antiplatelet and cytotoxic activity.

Nanostructures of undoped zinc oxide and nickel-doped zinc oxide (Ni = Zn0.98Ni0.02O, Zn0.96Ni0.04O, and Zn0.94Ni0.06O) were synthesized by using the coprecipitation process, and their optical and dielectric properties were simultaneously investigated. The XRD results confirm the hexagonal structure having space group P63mc. By increasing nickel concentration, the particle size decreases, while the strain is increased. Fourier-transform infrared (FTIR) analysis was carried out in order to learn more about the phonon modes present in nickel-doped zinc oxide. UV-Vis spectroscopy further revealed that the optical band gap of nickel-doped samples varied from 3.18 eV to 2.80 eV. The SEM analysis confirms the rod shape morphology of the already synthesized samples. EDX analysis investigates the incorporation of nickel ions into the zinc oxide lattice. Using photoluminescence spectroscopy, we found that the synthesized materials had oxygen vacancies (Vo) and zinc interstitial (Zni) defects. Dielectric constant (εr) and dielectric loss (ε) are both improved in nickel-doped zinc oxide compared to undoped zinc oxide. Since more charge carriers enhanced after the nickel ions were exchanged for the Zn ions, the AC electrical conductivity (σa.c) improves by nickel doping compared to undoped zinc oxide.

Nanoparticles have gained immense interest as probable drug molecules against microbial infections. Metal nanoparticles synthesized via exploring the reduction potential and capping activity of plants were found to have remarkable antimicrobial activity. The synthesis was conducted without hazardous chemicals and generation of toxic waste products. The focus of the study was, therefore, to investigate the efficacy of silver nanoparticles biosynthesized using Grewia tenax leaf extract as an antibacterial, antibiofilm, and antifungal therapeutic agent. The silver nanoparticles (GTAgNPs) were synthesized using optimized conditions of 2.5 mM AgNO3 and 1 : 10 ratio of 10% extract at 37°C on continuous stirring. The characterization was done by UV-visible spectroscopy, DLS, SEM, zeta potential, and FTIR. The antibacterial activity of GTAgNPs against both Gram (+) Bacillus cereus and Staphylococcus aureus and Gram (−) Escherichia coli and Pseudomonas aeruginosa bacteria via zone of inhibition, MIC, and MBC was analysed. The inhibitory effect of silver nanoparticles on biofilm formation was also observed against these bacteria. These nanoparticles were then evaluated for their potential antifungal activity against Candida albicans and Aspergillus niger by observing fungal growth inhibition. The probable mechanism of antimicrobial activity by GTAgNPs was studied by scanning electron microscopy which showed the significant formation of pores on the cell surface in GTAgNPs-treated microbial cells, leading to the death of the microbial cell. All these studies concluded that GTAgNPs possess the potent antimicrobial potential and can be employed as antimicrobial therapeutic agents.

Heat transfer characteristics of graphene oxide (GO)/turbine oil as a non‐Newtonian nanofluid are assessed both experimentally and numerically in this paper. To do so, 0.2, 0.3, 0.5, and 1 mass percent (wt%) of GO is homogeneously dispersed in the base liquid. First, the specific heat capacity, thermal conductivity, viscosity, and density of the synthesized nanofluids are measured using standard laboratory methods. After that, constants of the shear stress equation are determined through the nonlinear regression of the rheology data on the power law model. Finally, the heat transfer from turbine blades with a constant surface temperature to the coolant nanofluid is investigated using mathematical modeling. The results suggest that while the nanofluid density, viscosity, and thermal conductivity increase by increasing the nanoparticle concentration by 0.57%, 7.07%, and 18.89% in succession, respectively, and its specific heat capacity decreases by 0.54%. Moreover, both the convective heat transfer coefficient and the temperature profile in the considered nanofluids depend on the average velocity and Reynolds number. Furthermore, the convective heat transfer coefficient increases by 5.5%, 9.5%, 14%, and 17% in exchange for 0.2, 0.3, 0.5, and 1 wt% of GO nanoparticles in the base liquid, respectively.