Applied Nanoscience最新文献

This study presents a method for synthesizing superparamagnetic nanoparticles through the co-precipitation method, with a coating of tetrahydroxy-1,4-quinone (THQ). The diameter of the magnetite nanoparticles (MNPs) covered with THQ varied depending on the recovery method applied. When collected through magnetic decantation, they exhibited an average diameter of 15 ± 3 nm, while centrifugation of the supernatant further reduced the diameter to 12 ± 3 nm. In contrast, the uncoated MNPs had an average diameter of 17 ± 5 nm. The smaller MNPs coated with THQ displayed very low magnetic hysteresis and demonstrated superparamagnetic behavior, indicated by a blocking temperature of less than 300 K. Characterization of both the coated and uncoated MNPs encompassed structural, morphological, size, and magnetic property analyses using X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM), respectively. Fourier-transform infrared spectroscopy (FT-IR) and UV–Vis spectroscopy were employed to investigate the chemical interaction between THQ and the MNPs. In addition, cyclic voltammetry was used to compare the electrochemical changes of THQ, MNPs, and MNPs coated with THQ.

This study focuses on the facile combustion synthesis of highly luminescent Y₂O₃:Sm³⁺, Gd³⁺ nanophosphors, bringing down the thermal budget to a minimum of 500 K. When Sm³⁺ ions are doped in the Y₂O₃ cubic crystal system of bandgap 5.6 eV and studied under a down-conversion excitation of 260 nm, the emission spectra offered an intense vermilion color at 608 nm due to the ⁴G_5/2 → ⁶H_7/2 transition within the Sm³⁺ ions. The Y₂O₃:2wt%Sm³⁺ matrix is co-doped with 3wt%Gd³⁺, highlighting 100% pure vermilion emission 4.21 times higher than doped samples, which is a perfect choice for domestic lightening owing to better eye compatibility. Further, post-annealing is performed to improve the structural parameters and luminescence properties, creating sufficient alterations in the crystal lattice. It is professed that Y₂O₃:Sm³⁺, Gd³⁺ nanophosphors can be effectively used in optoelectronic devices, owing to their enhanced crystallinity and photoluminescence properties resulting from the Gd³⁺ → Sm³⁺ energy transfer efficiency of 75.15%.

Ammonia gas detection has garnered widespread attention in various fields, including food, environmental industries, and medical diagnostics. In this article, we present the synthesis of graphene-based tin oxide (graphene–SnO₂) hybrid nanostructures using the hydrothermal method. Pristine tin oxide nanostructures and a series of graphene-based tin oxide hybrids containing 5 wt.%, 10 wt. %, 15 wt. %, and 20 wt. % graphene concentrations were fabricated to investigate their response as ammonia gas sensors. The X-ray diffraction and high-resolution transmission electron microscopy analysis revealed the tetragonal rutile crystal structure of both pristine SnO₂ and graphene–SnO₂ hybrid structures. The morphology of the synthesized structures was examined using scanning electron microscopy. Fourier transform infrared spectroscopy was employed to validate the functional groups present in the hybrid structures, while the band gap of the graphene–SnO₂ nanohybrid structures was determined using diffuse reflectance spectroscopy. X-ray photoelectron spectroscopy was utilized to investigate the chemical composition, electronic state, and bonding of the materials. Four probe current–voltage (I–V) measurements were conducted to investigate conductivity and ammonia-sensing behavior. Upon exposure to ammonia gas fumes, the pristine SnO₂ exhibited changes in current and resistance, ranging from 0.063 mA to 3.75 mA and 15.87 kΩ to 266.67 Ω, respectively. Similarly, the ammonia sensing behavior of hybrid structures containing 20 wt. % graphene showed changes in current and resistance, ranging from 5.42 mA to 37.8 mA and 0.18 kΩ to 26.45 Ω, respectively. These findings suggest that graphene–SnO₂ hybrid structures exhibit excellent conductivity when exposed to NH₃ gas, unlike their ammonia-absence counterparts.

The present study demonstrates the creation of silver nanoparticles (Ag NPs) in an environmentally benign manner from Cymbopogon citratus leaves extracts by employing microwave-assisted synthesis at a low power of 400 W for a short period of 180 s. The produced Ag NPs are thoroughly characterized using methods like X-ray diffraction (XRD), UV–visible spectroscopy, scanning electron microscopy (SEM), and X-ray energy dispersive spectroscopy (EDS). These Ag NPs form clusters and have unique plate-like shapes with average particle size of ~ 165 nm. To evaluate their antibacterial activity, the produced Ag NPs are tested against both gram-positive bacteria (S. aureus) and gram-negative bacteria (E. Coli, S. typhi, and Pseudomonas) at varied concentrations (1–5 mg/L). The results show strong antibacterial activity, against both gram-positive bacteria (S. aureus) and gram-negative bacteria (E. Coli, S. typhi, and Pseudomonas); and show the largest zone of inhibition diameters at 23 mm (~ 3 mg/L) and 26 mm (~ 5 mg/L) for S. aureus and Pseudomonas, respectively. The ecological potential of Cymbopogon citratus extracts as sources for the environmentally friendly synthesis of Ag NPs is highlighted in this work and the produced Ag NPs are a viable option for antibacterial treatments against pathogenic microbes.

This study investigates the enhancement of molybdenum disulfide (MoS₂) nanoparticles with polyethylene glycol (PEG) to improve peroxidase activity and antibiotic degradation capabilities. X-ray photoelectron spectroscopy confirmed successful modification, showing shifts in Mo and S binding energies. Scanning electron microscopy revealed an increase in nanoparticle size from 117.8–178.74 nm (MoS₂) to 99.73–200.20 µm (MoS₂-PEG), likely due to agglomeration. MoS₂-PEG demonstrated optimal peroxidase activity at 60 µg/mL concentration and 12 mM H₂O₂, with maximum efficiency at pH 5 and 30 °C, highlighting its pH sensitivity and moderate thermal stability. Under these conditions, MoS₂-PEG achieved nearly complete degradation of 10 mg/L Cefotaxime (CFX) within 312 min, identifying three metabolites (CFX 1, CFX 2, and CFX 3) in the degradation pathway. The study concludes that MoS₂-PEG nanoparticles are effective for peroxidase reactions and antibiotic degradation, positioning them as promising candidates for wastewater treatment. Their stability, reusability, and potential for sustainable applications underscore their value in developing cost-effective solutions for removing antibiotics from contaminated water sources.

The present work summarizes the mechanical, tribological, and corrosion properties of the aluminum 6061 alloy composite that has been strengthened with a novel combination of 2 wt% nano-silicon dioxide (nSiO₂) and varying percentages of tungsten carbide (WC) particles. Microstructural analysis, microhardness, tensile testing, impact testing, and porosity measures have all been assessed in addition to wear and corrosion studies. The results showed that adding 2 wt% nSiO₂ to the Al matrix caused the porosity of the composites to decrease, and adding WC caused it to rise. All composites exhibited an improvement in hardness but a decrease in impact strength. The composite containing 9 wt% WC (NAC4) has a hardness that is 2.3, 1.58, 1.35, and 1.25 times greater than that of the ACA, NAC1, NAC2, and NAC3 composites, in that order. The addition of nSiO₂ and an increasing amount of WC reduces elongation and increases tensile strength. The ultimate tensile strength of the NAC4 composites increased by 46.72, 27.86, 24.59, and 10.65%, respectively, compared to the ACA, NAC1, NAC2, and NAC3 composites. The cracked surface of the nSiO₂ with WC-reinforced composites displays a mixed fracture mechanism with dimples, voids, and cracks. In the wear test under 30 N load, the NAC4 composite shows 5.27, 4.72, 4.02, and 1.12 times lower wear rates than ACA, NAC1, NAC2, and NAC3 composites, respectively. As the concentration of WC particles increases, composites become more resistant to corrosion. According to the results, the polarization curve demonstrated a positive shift in E_corr from − 1.189 to − 0.656 V as the amount of WC increased, and the i_corr decreased to 4.974 × 10^–4 from 7.695 × 10^–4 A/cm².

This study examines the impact of copper oxide (CuO), iron oxide (Fe₃O₄), and their composite (Fe₃O₄@CuO) nanoparticles on harmful microorganisms in tomato plant roots and stems. The research evaluates agro-environmental factors, including soil composition, moisture levels, and temperature, that influence the efficacy of these nanoparticles. The nanoparticles prepared by the PLAL technique were subjected to structural, morphological, topographic, and optical analysis using a range of methods, including XRD, FE-SEM, EDS, AFM, and UV–Visible spectroscopy. The copper and iron composite particles were found to be polycrystalline, with the iron element present in magnetite and hematite phases. The particles exhibited a spherical form, however, there was agglomeration between them. The optical characteristics exhibited plasmon resonance peaks, indicating the transition of the materials into an optimal nanoscale phase. Both laboratory and field studies were conducted to assess their antifungal activity. The findings reveal that the Fe₃O₄@CuO composite exhibited superior pathogen suppression compared to the individual nanoparticles. This research offers valuable insights into the application of nanoparticles for controlling plant fungal and bacterial diseases, contributing to more effective and sustainable agricultural practices.

The present research explores the dispersion of SiO₂ nanoparticles in compressor lubricant, polyolester (POE) oil for performance enhancement of vapour compression refrigeration system (VCRS). The contribution of SiO₂ nanoparticles based nanolubricant was examined for eco-friendly hydrocarbon (HC) refrigerant R600a, retrofitted to hydrofluorocarbon (HFC) compressor based VCRS and also in HC compressor, in governing the performance of VCRS. Wear characteristics improved by the nanolubricants were assessed through pin-on-disc wear testing, using the pins extracted from the actual compressor piston used in VCRS. As compared to POE oil, the average specific wear rate (SWR) and coefficient of friction (COF) of nanolubricant were reduced by about 20% and 29%, respectively. Enhanced average viscosity and average thermal conductivity were observed (35–95 °C), with maximum increases of about 13% at 65 °C and 45% at 95 °C, respectively, in comparison to those of POE oil. Field emission scanning electron microscopy (FE-SEM) was utilized to analyze the morphology of SiO₂ nanoparticles, while Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyzed their crystal structure. The Zeta potential tests for the prepared nanolubricant were conducted to ensure its long-term stability. An HC compressor based VCRS shows better performance including average refrigeration effect, average power consumption by compressor, and the average coefficient of performance (COP) of 29%, 7%, and 39%, respectively compared to the base lubricant filled retrofitted system. Hence the findings of the present research provide novel perspectives on the potential benefits of incorporating SiO₂ nanoparticles and an HC compressor to improve the VCRS performance.

In recent years, there has been an exponential increase in the production of silver bionanoparticles due to their widespread commercialization and technological applications. However, there is limited understanding of the impact of silver bionanoparticles on biological agents commonly used in wastewater treatment, particularly in waste stabilization ponds (WSPs). This study aimed to synthesize new silver nanoparticles (sg-AgNPs) from Synadenium glaucescens root using an environmentally friendly method and optimized biosynthesis parameters, and evaluate their antimicrobial activity and ecotoxicological impact on WSPs using standardized approaches. The average primary sizes of the sg-AgNPs in the five samples were not significantly different (P > 0.05), indicating the effectiveness of the eco-friendly method and the importance of optimal biosynthesis conditions. Analysis from UV–Vis spectroscopy, energy-dispersive spectroscopy (EDX), transmission electron microscope (TEM), and X-ray diffraction (XRD) confirmed that sg-AgNPs exhibited typical characteristics of green silver nanoparticles. Furthermore, sg-AgNPs showed strong antimicrobial activity (MIC, 0.012–0.094 mg/ml) against gram-positive bacteria (Escherichia coli), gram-negative bacteria (Staphylococcus aureus), non-filamentous fungi (Candida albicans) and filamentous fungi (Aspergillus niger). While the Synadenium glaucescens root proved to be a valuable precursor for producing effective antimicrobial sg-AgNPs, the introduction of sg-AgNPs into WSPs significantly impacted algal chlorophyll-a production and survival of ostracod population. These results shed light on the ecotoxicological risks of sg-AgNPs for WSPs organisms and highlight the suitability of algae and ostracods as model organisms for ecotoxicological studies in WSPs.