Nanomaterials and Nanotechnology

Nanostructures of undoped zinc oxide and nickel-doped zinc oxide (Ni = Zn_0.98Ni_0.02O, Zn_0.96Ni_0.04O, and Zn_0.94Ni_0.06O) 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 (Zn_i) defects. Dielectric constant () 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 () 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.

Multigroup large-scalenanocutting models of monocrystalline Cu were established by molecular dynamics simulations to investigate the influence of cutting parameters on the material removal mechanism. The formation and distribution of subsurface defect structures were revealed, and the evolution behavior of the complete prismatic dislocation loop was analyzed in depth. It was demonstrated that the chips and machined surface of monocrystalline Cu were mainly formed under the coupling effect of shearing and extrusion forces. A diamond tool with a larger edge radius or a negative rake angle could produce a noticeable suppression on the chip formation. The corresponding relationship between the location of defect atoms and the distribution of von Mises stress was studied, which indicated that the shear stress would become larger at the subgrain boundaries, dislocation lines, and the amorphous atoms than that in their nearby regions. The complete prismatic dislocation loop was formed by cross-slip between two sets of stacking faults; meanwhile, the generated multiple Lomer–Cottrell locks hindered its movement and promoted the work-hardening phenomenon. These research results are of great theoretical value to enrich the nanocutting mechanism and technology of plastic materials.

Herein, we synthesized gold-coated ZnO/Fe₃O₄ nanocomposites. Initially, we prepared Fe₃O₄ magnetic nanoparticles based on the co-precipitation of Fe³⁺ and Fe²⁺ under aqueous ammonia as a precipitating agent. Thereafter, the ZnO/Fe₃O₄ composite was prepared by dispersing the synthesized magnetic nanoparticles into an alkaline zinc nitrate solution. After calcination of the precipitate, the formed ZnO/Fe₃O₄ composites were coated with gold nanostructures by dispersing the composites in auric acid/ethylene glycol solution in a water bath. The synthesized Au@ZnO/Fe₃O₄ hybrid material was able to catalyze the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). We demonstrate that this catalytic activity can be exploited for the detection of Hg²⁺ ions in a cosmetic product. In the presence of Hg²⁺ ions, the catalytic activity of Au@ZnO/Fe₃O₄ was greatly suppressed. This novel finding underlies a straightforward, sensitive, and highly selective detection probe for Hg²⁺. The material exhibited excellent analytical performance as marked by the very low limit of detection (LOD) of 2.34 nM, which was well below acceptable levels of 4.99 μM for mercury in cosmetics as set by the US Food and Drug Administration (FDA), and within the linear dynamic ranges of 0–10 nM. High recoveries ranging from 96.5 to 100.3% accompanied by excellent selectivities toward Hg²⁺ over potentially interfering species were obtained.

In this study, an all-optical multiplexer (Mux) based on elliptical insulator-metal-insulator (IMI) plasmonic waveguides is designed. The area of the proposed structure is very small (400 nm × 400 nm) which operates at a wavelength of 1,550 nm. The developed device utilizes constructive and destructive interferences between the input signals and the selector signal. This structure is less complex and has lower loss compared to the previous works. Transmission (T), contrast ratio (CR), modulation depth (MD), insertion loss (IL), and contrast loss (CL) are the five parameters that describe the performance of the plasmonic Mux. The transmission threshold between logic 0 and logic 1 is 0.5. Moreover, the maximum transmission efficiency of the device is 163%. Moreover, based on the MD value of 95.09%, the dimensions of the proposed structure are excellent and optimal. The proposed plasmonic Mux structure contributes substantially to developing an all-optical arithmetic logic unit (ALU) and all-optical signal processing nanocircuits. The finite element method (FEM) simulates the proposed plasmonic multiplexer with COMSOL Multiphysics 5.4 software.

This study synthesized carbon quantum dots (CQDs) with green photoluminescence through a hydrothermal method that utilized mulberry juice as the carbon source. The influence of fruit ripeness on the physical and chemical properties, focusing on the fluorescence spectra, has been explored. Fourier-transform infrared spectroscopy (FT-IR) and energy dispersive X-ray analysis (EDX) showed that there were oxygen-containing groups, and X-ray diffraction (XRD) showed that the carbon quantum dots (CQDs) were graphitic. The results revealed that the CQDs had an average size of around 7.4 nm and 9.7 nm for unripe and ripe mulberry juice, respectively. These CQDs emitted green light at 500 nm and 510 nm in unripe and ripe mulberry juice, respectively, when excited at a wavelength of 400 nm. The prepared CQDs exhibited excitation-dependent photoluminescence (PL) emission behavior, demonstrating their dependence on the excitation light. The impact of fruit ripeness on optical properties was explored by examining fluorescent spectra from different fruits (including tomato and blackberry), demonstrating comparable behaviors observed in mulberry fruit. In addition, the prepared CQDs were utilized as a fluorescent sensor with high specificity to detect Cu²⁺ ions. The detection limit (DL) for this sensor was determined to be 0.2687 µM, and the limit of qualification (LOQ) is 0.814 µM. The linear range for detection lies between 0.1 and 1 µM. The selectivity of the CQDs towards Cu²⁺ ions was confirmed by recording the PL response for Cu²⁺ ions compared to the weak response of other metal ions. According to these results, the CQDs can be applied in various cellular imaging and biology applications, bio-sensing, optoelectronics, and sensors.