Metallic Silver Nanoparticles Research Articles

A review of the antimicrobial benefits of naturally extracted nanomaterials

Nanotechnology finds immense potential due to the unique characteristics of nanomaterials. Though noble metal nanoparticles, particularly gold and silver nanoparticles possess advanced properties their conventional production methods pose environmental hazards. This paper explores the eco-friendly approaches using natural sources for synthesizing gold and silver nanoparticles. Rose and pomegranate extracts were used to synthesize gold nanoparticles. Evaluation using ultraviolet-visible (UV-Vis) spectroscopy confirmed the nanoparticle formation, and Fourier transform infrared spectroscopy (FT-IR) analysis recognized the presence of plant-derived compounds for stabilizing these particles. In-depth observations of their size and form were provided using electron microscopy, and these findings were aligned with the inferences made from the UV-Vis data. Silver nanoparticles were produced using Ocimum gratissimum leaf extract (OGE), exhibiting dose-dependent antimicrobial effects against bacterial strains. A comparative analysis demonstrated the distinct antibacterial characteristics of silver and gold nanoparticles against several bacterial strains. These nanoparticles demonstrated enhanced inhibitory effects when employed in combination with antibiotics, suggesting the possibility of dealing with antibiotic resistance. The study presents opportunities for producing nanomaterials with minimal impact on the environment and for addressing antibiotic resistance. Further research can enhance the process and find more useful applications as this green synthesis approach can bring about significant improvements in many areas.

Numerically investigating the effect of using nanofluids on the thermal performance and coefficient of performance of a U-tube deep borehole ground source heat pump

In this study, a deep-borehole ground source heat pump was simulated using computational fluid dynamics (CFD) method. The thermal performance and coefficient of performance (COP) of the vertical ground source heat pump simulated with accuracy using CFD for water and 4 different nanofluids as working fluids were investigated. Two nanofluids contained silver and copper metallic nanoparticles and the other two nanofluids contained copper and aluminum oxide nanoparticles. For each of these nanofluids as well as water, the heat exchange rate, total exchanged heat, outlet temperature and COP were calculated and the results were compared together. The results showed that using nanofluids leads to increased exchanged heat. Nanofluids based on aluminum oxide, copper oxide, copper and silver nanoparticles resulted in 4.83, 5.76, 6.9, 7.69 percent increase in total exchanged heat, respectively. In addition to increased exchanged heat, using nanofluids increased the outlet temperature. Also, the results showed that the maximum and minimum increase in COP were 36.5% and 5.2% which were related to using silver and aluminum oxide nanoparticle-based nanofluids, respectively.

Equilibrium structure and shape of Ag and Pt nanoparticles grown on silica surfaces: From experimental investigations to the determination of a metal-silica potential.

A combination of experimental and numerical investigations on metallic silver and platinum nanoparticles deposited on silica substrates is presented, with a focus on metal-substrate interactions. Experimentally, the nanoparticles, obtained by ultra-high vacuum atom deposition, are characterized by grazing-incidence small-angle x-ray scattering and high resolution transmission electronic microscopy to determine their structure and morphology and, in particular, their aspect ratio (height/diameter), which quantifies the metal-substrate interaction, from the as-grown to equilibrium state. Numerically, the interactions between the metal and the silica species are modeled with the Lennard-Jones (12, 6) potential, with two parameters for each metal and silica species. The geometric parameters were found in the literature, while the energetic parameters were determined from our experimental measurements of the aspect ratio. The parameters are as follows: σAg-O = 0.278nm, σAg-Si = 0.329nm, ɛAg-O = 75meV, and ɛAg-Si = 13meV for Ag-silica and σPt-O = 0.273nm, σPt-Si = 0.324nm, ɛPt-O = 110meV, and ɛPt-Si = 18 meV for Pt-silica. The proposed Ag-silica potential reproduces quantitatively the unexpected experimental observation of the variation of the aspect ratio for Ag nanoparticles larger than 5nm, which has been interpreted as a consequence of the silica roughness. The nanoparticle orientation, structure, and disorder are also considered. This metal-silica potential for Ag and Pt should be helpful for further studies on pure metals as well as their alloys.

Synthesis of multifunctional silver oxide, zinc oxide, copper oxide and gold nanoparticles for enhanced antibacterial activity against ESKAPE pathogens and antioxidant, anticancer activities using Momordica cymbalaria seed extract

Rising emergence in public health due to antibiotic-resistant of ESKAPE pathogens, diseases related to oxidative damage and cancer has driven the urgent need to develop potent therapeutics for resistant bacterial strains, free radical scavenging and cancer. The present study involves Momordica cymbalaria seed extracts mediated synthesis of metal nanoparticles and to evaluate its ameliorative potency against ESKAPE pathogens, free radicals and cancer cells. The study includes therapeutic approaches to target pathogenic biofilms relating phyto-therapeutics with nanotechnology. In the present investigation, we have synthesized four metal oxide nanoparticles of Silver, Zinc, Copper (Ag2O, ZnO and CuO), and Gold nanoparticles (Au NPs) using the seed extracts of M. cymbalaria. The synthesized nanoparticles were characterized by various biophysical techniques like X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) Field-Emission Scanning Electron Microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDX) and High-Resolution Transmission Electron Microscopy (HR-TEM) with Selected Area Electron Diffraction (SAED). Agar well diffusion methods, or Antimicrobial methods (MIC, MBC, and MBIC), DPPH/ABTS free radical scavenging assay, MTT/apoptotic studies and protein/DNA damage inhibition assays were performed to evaluate the antibacterial, anticancer and antioxidant activities. Crystalline properties of metal oxides NPs were established by XRD pattern and the presence of alcohol or phenol, ketone, and amine groups in M. cymbalaria seed was confirmed by FTIR analysis. That participates in the reduction of Ag+, Cu+, Zn+, and Au+ ions to NPs. All the nanoparticles showed dose-dependent antibacterial, anticancer and antioxidant activity. Protein and DNA oxidation inhibition assays demonstrated an efficient quenching effect of proxy radicals by all the NPs. Therefore, M. cymbalaria -mediated synthesis of metal NPs can be used as an alternative to toxic physical or chemically mediated synthesis that can be applied to develop multifunctional nanoparticles as efficient therapeutics.

Effect of Metal Nanoparticles in the Field Emission of Silicon Nanowires

In this work, an efficient method is reported for creating a metal nanoparticle (silver) / Si composite structure consisting of a vertical array of silicon nanowires (SiNWs) decorated with silver metal nanoparticles. A two-stage metal-assisted etching method is employed to obtain SiNWs and Silver (Ag) metal nanoparticles are decorated on the SiNWs using the electroless deposition method. It allows the good coverage of silver metal nanoparticles over SiNWs. Scanning Electron Microscopy (SEM) analysis revealed that Ag was covered with SiNWs. High-work function metal nanoparticles such as Ag nanoparticles on SiNWs have been utilized in different applications such as photovoltaics and sensors. The size of SiNWs is determined through the Raman shift. The silicon optical phonon peak showed an increase in redshift and a decrease of full-width at half maxima with a decrease in diameter due to the quantum confinement. The Electron Field Emission (EFE) characteristics of the Agdecorated SiNW films were studied based on the current-voltage measurements and analyzed using the Fowler-Nordheim (F-N) equation. The low turn-on field is obtained through the Ag metal nanoparticles which have wider applications in lowpower operational devices.

UV-light-responsive Ag/TiO2/PVA nanocomposite for photocatalytic degradation of Cr, Ni, Zn, and Cu heavy metal ions

The rapid growth of industrialization has led to the uncontrolled pollution of the environment, and rapid action is needed. This study synthesized Ag/TiO2/polyvinyl alcohol (PVA) nano photocatalyst for promising light-derived photocatalytic removal of heavy metal ions. The design of experiment (DOE) was used to study the effect of important factors (pH, reaction time, and photocatalyst dosage) to maximize the final performance of the photocatalyst. In the optimized condition, the Ag/TiO2/PVA nano-photocatalyst removed more than 94% of Cr6+ in 180 min, and the efficiency was more than 70% for Cu2+, Zn2+, and Ni2+ metal ions. The adsorption of the heavy metal ions on the photocatalyst was described well with the Langmuir isotherm, while the pseudo-second-order linear kinetic model fitted with the experimental data. The nano-photocatalyst's stability was confirmed after maintaining its performance for five successive runs. The enhanced photocatalytic activity for the heavy metal ions removal can be attributed to the presence of metallic silver nanoparticles (electron transfer and plasmonic fields mechanisms) and PVA, which delayed the recombination of electron–hole. The synthesized ternary Ag/TiO2/PVA nano-photocatalyst showed promising performance for the elimination of heavy metal ions and can be used for environmental remediation purposes.

Antibacterial Activity Test of Ag Nanoparticle Soap Turi Leaf Extract (Sesbania grandiflora) Against Staphylococcus aureus Bacteria

Silver metal nanoparticles have biocidal properties as a non-toxic inorganic antibacterial agent. Flavonoid compounds from the Turi Leaf (Sesbania grandiflora) plant extract as a natural bio reductant. In the research, UV-Vis spectrophotometric testing parameters and antibacterial soap preparations were carried out. Synthesis and Characteristics of Silver Nanoparticles were carried out, with soap preparations made into 3 formulas with different variations in Agno3 concentration, namely 1 mM, 2 mM, and 3 mM and antibacterial activity tested using well diffusion. The results of the absorption spectrum of Ag nanoparticles show the highest peak at a value of 280-290 nm. In the antibacterial activity test, the greater the AgNO3 concentration in the Ag nanoparticle soap, the greater the inhibition zone created by Staphylococcus aureus bacteria. The optimum concentration in soap preparations is 3 mM producing a wavelength of 300 nm with an absorbance value of 1.105. In terms of antibacterial activity, the most effective way to inhibit the growth of Staphylococcus aureus bacteria is formulation III, with an inhibitory power of 7.69 cm2 .

Photocatalytic oxidation of methane to methanol over zinc titanate supported silver catalysts

The direct activation of methane under mild condition to achieve highly selective of oxygenates is a challenging project. In this study, a well dispersed silver supported ZnTiO3 catalyst was prepared to achieve selective preparation of methanol from methane and water under mild condition. X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy characterizations demonstrate that silver species are uniformly dispersed on ZnTiO3 surface in the form of metallic silver nanoparticles. The photoelectric characterizations reveal that the addition of silver species enhances light absorption and promotes charge separation of the catalysts. Under the reaction conditions of 50 °C and 3 MPa, the methanol is obtained as the only liquid product over the designed Ag/ZnTiO3 catalyst under light irradiation. In this photocatalytic process, the holes generated by ZnTiO3 activate water to produce intermediate ·OH, which further reacts with methane to synthesize methanol. The silver species as co-catalysts extend the light absorption range of ZnTiO3 as well as promote charge separation.

Synthesis of Silver Nanoparticles Using Potato Cultivars with Their Antioxidant Activity

ABSTRACT Plant-mediated processes offer a more straightforward and cost-effective alternative to conventional chemical and physical methods for the reduction of silver ions to silver metallic nanoparticles. This study was conducted to synthesize silver nanoparticles (AgNPs) using a solution of silver nitrate (AgNO3) and a local Basciftlik white potato cultivar (S. tuberosum). Furthermore, the study aimed to compare antioxidant activity of nano-silver particles with that of the potato extract. The potato cultivar was extracted with deionized water and the solution was filtrated. The filtrate was reacted with AgNO3 solution to obtain the AgNPs. The structure of synthesized AgNPs was determined by a spectroscopic study, and characteristic functional groups were analyzed by a fourier-transform infrared spectroscopy (FTIR). The signal observed at 3267 cm−1 is indicative of the hydroxyl functional group. The highest absorption at 429 nm in ultraviolet-visible (UV-VIS) spectrum confirmed the occurrence of the synthesized AgNPs. The biogenic crystalline structure of the synthesized AgNPs was verified by an X-ray diffraction analysis. Average size and morphology of the St-AgNPs were determined by Scanning Electron Microscope analysis, which also indicated the formation of the AgNPs with an average size of 37.31 nm. Antioxidant activity study revealed that the synthesized AgNPs had higher antioxidant activity compared to that of the potato extract alone.

In Situ Crystallization, Differential Growth, and Multicolor Emission of Silver Nanoclusters.

The real-time monitoring of the stepwise growth process of the molecular crystal reveals a conclusive understanding of the morphological evolution, which otherwise remains elusive during the conventional crystallization processes. Herein, we report the in situ crystallization of silver nanoclusters (AgNCs) with special emphasis on their differential growth and multicolor emissive properties. A subtle variation of the methanol (MeOH) proportion in the reaction mixture induces the differential growth of these AgNCs, and thereby, a dramatic modulation in their optical properties was observed. Additionally, by increasing the temperature of the reaction (from a low temperature ice bath to 25 °C), an uncontrolled formation of AgNCs along with metallic silver nanoparticles (AgNPs) was observed, which was primarily induced by accelerating the reaction kinetics. We hope that this investigation comprehensively uncovers the serious bottlenecks of the conventional crystallization processes by showcasing systematic monitoring of structural evolution to the higher-ordered crystalline state.

A chemically functionalized glass support for gold and silver metallic nanoparticle analysis with LIBS

For the first time ever, the LIBS technique has been applied for the metal nanoparticle analysis, using a novel custom-designed silane-functionalized sample support for LIBS-based metallic nanoparticle analysis.

Characterization of silver sulfide nanoparticles from actinobacterial strain (M10A62) and its toxicity against lepidopteran and dipterans insect species

Abstract In this research, cell-free extracts from magnesite mine-isolated actinobacterial strain (M10A62) were used to produce silver sulfide nanoparticles (Ag2SNPs). Streptomyces minutiscleroticus JX905302, actinobacteria capable of producing Ag2SNPs, was used to synthesize Ag2NPs. The UV–vis range was used to confirm the biosynthesized Ag2NPs; Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), and dynamic light scattering analysis were employed to characterize them further. Surface resonance plasma (SRP) for Ag2SNPs was obtained at 355 nm using UV–visible spectroscopy; FT-IR detected bimolecular and eventually microbial-reduced Ag2SNPs from S. minutiscleroticus culture extract. Furthermore, AFM and TEM analysis confirms that the synthesized Ag2SNPs were spherical in shape. Dynamic light scattering revealed a negatively charged Ag2NPs surface with a diameter of 10 nm. The XRD spectrum showed the crystalline nature of the obtained particles. EDAX revealed a pure crystalline nature, and a significant silver particle signal confirms the presence of metallic silver and sulfide nanoparticles together with the signals of Cu and C atoms. After 40 and 48 h of treatment at 150–200 µg·ml−1, Ag2SNPs produced the highest mortality in Spodoptera litura, H. armigera, Aedes aegypti, and Culex quinquefasciatus larvae. Hence, the biosynthesized Ag2SNPs may be useful for potential pest control in integrated pest management and vector control program as a safer, cost-effective, selective, and environmentally friendly approaches.

One-step silver coating of polypropylene surgical mask with antibacterial and antiviral properties

Face masks can filter droplets containing viruses and bacteria minimizing the transmission and spread of respiratory pathogens but are also an indirect source of microbes transmission.A novel antibacterial and antiviral Ag-coated polypropylene surgical mask obtained through the in situ and one-step deposition of metallic silver nanoparticles, synthesized by silver mirror reaction combined with sonication or agitation methods, is proposed in this study.SEM analysis shows Ag nanoparticles fused together in a continuous and dense layer for the coating obtained by sonication, whereas individual Ag nanoparticles around 150 nm were obtained combining the silver mirror reaction with agitation. EDX, XRD and XPS confirm the presence of metallic Ag in both coatings and also oxidized Ag in samples by agitation. A higher amount of Ag nanoparticles is deposited on samples by sonication, as calculated by TGA. Further, both coatings are biocompatible and show antibacterial properties: coating by sonication caused 24 % and 40 % of bacterial reduction while coating by agitation 48 % and 96 % against S. aureus and E. coli, respectively. At 1 min of contact with SARS-CoV-2, the coating by agitation has an antiviral capacity of 75 % against 24 % of the one by sonication. At 1 h, both coatings achieve 100 % of viral inhibition. Nonetheless, larger samples could be produced only through the silver mirror reaction combined with agitation, preserving the integrity of the mask.In conclusion, the silver-coated mask produced by silver mirror reaction combined with agitation is scalable, has excellent physico-chemical characteristics as well as significant biological properties, with higher antimicrobial activities, providing additional protection and preventing the indirect transmission of pathogens.

Silver-modification of ZnO thin films deposited on Zn-electroplated Cu substrate by thermal shock method for the enhanced photocatalytic performance

Ag-modified ZnO thin films on Zn-electroplated Cu substrate with different Ag-contents were prepared via a simple sol–gel spin-coating procedure followed by a thermal shock method with AgNO3, and then characterized by XRD, Raman, FTIR, FESEM, EDX, and UV-visible absorption spectroscopy. Their photocatalytic performance was evaluated by the degradation of methylene blue. Due to the sol–gel spin-coating process, the film was successfully immobilized on mechanically robust Zn/Cu plates, making it promising for applications in harsh practical conditions and facilitating recovery. When our ZnO thin films were surface-modified with AgNO3 at 1 and 2 mol%, they exhibited the best photocatalytic activity under UVA light and visible light, respectively, which can be explained by the appearance of maze-like architecture on their surface with vertical ZnO walls, surface defects and metallic silver nanoparticles. However, when the Ag-content was increased to 3 mol%, the maze-like structure collapsed, leading to decreases in photocatalytic performance.

Revolutionizing Imaging and Diagnostics: Harnessing Metallic Nanoparticles and Nanocarriers for Cutting-Edge Theranostics

The field of medical diagnostics and therapeutics is currently undergoing a transformative revolution, driven by the rapid advancements in nanotechnology. This paper explores the promising potential of metallic nanoparticles and nanocarriers in the realm of theranostics, a fusion of therapy and diagnostics, offering unprecedented opportunities for precision medicine and patient care. The integration of metallic nanoparticles and nanocarriers into medical applications has opened new frontiers for non-invasive imaging and targeted therapy. This review provides an in-depth analysis of metallic nanoparticles, including gold, silver, and magnetic nanoparticles, highlighting their unique physicochemical properties that make them ideal candidates for imaging and therapeutic purposes. Additionally, we discuss the evolution of nanocarriers, such as liposomes, micelles, and dendrimers, and their role in enhancing drug delivery, bioavailability, and treatment specificity. The versatility of metallic nanoparticles and nanocarriers in both imaging and therapeutic applications is showcased through their utilization in areas such as cancer diagnosis, drug delivery, and the management of neurological disorders. Furthermore, their potential to enable real-time monitoring of treatment responses and disease progression is explored, empowering clinicians with essential tools for personalized medicine. Challenges and considerations related to toxicity, biocompatibility, and regulatory hurdles are also discussed, shedding light on the need for further research and collaboration between scientists, clinicians, and regulatory bodies. As metallic nanoparticles and nanocarriers continue to evolve, they promise to revolutionize the landscape of medical diagnostics and therapy, ultimately improving patient outcomes and enhancing the effectiveness of healthcare practices. This paper serves as a comprehensive overview of the current state and future prospects of these groundbreaking technologies, contributing to the advancement of theranostics and its wide-reaching implications for the healthcare industry.

Role Of In- Situ Rutin Flavonoid Consisted Myristica Fragrans Silver Nano Particles (MF-Ag-Nps) Against Escherichia Coli and Bacillus Subtilis

Most microbiological growth inhibitors are toxic and chemical solvents are harmful for human health. Copper, silver, and gold metallic nanoparticles have several uses in biotechnology and medicinal research. MF-Ag-NPs(silver nanoparticles)are potent anti-inflammatory, anti-proliferative, and anti-microbial agents. The purpose of this study was to biogenically generate silver nanoparticles by extracting rutin from nutmeg, a seed from the Myristica fragrans plant. In order to create Myristica fragrans MF-Ag-NPs, silver nitrate was dissolved in the extract. The transformation of the colour from dark brown to pale brown confirmed the conversion of Ag+ to Ag°. FTIR, EDX, and SEM were used to describe them. Images from scanning electron microscopy demonstrate the presence of silver nanoparticles between 20 and 300 nm in size. The presence of oxygen and silver, as well as the metal's oxidation state, were confirmed by EDAX analysis. The nanoparticles' distinctive functional groups were discovered using FTIR spectroscopy. The antibacterial activity of Myristica fragrans seed extract was assessed. The extract from the seeds of Myrsitica fragrans exhibited the strongest antibacterial properties. These findings imply that antibacterial MF-Ag-NPs phyto-formulated with nutmeg extracts might be used to treat microbial infections in the future.

Photochemical Synthesis of Noble Metal Nanoparticles: Influence of Metal Salt Concentration on Size and Distribution.

This paper explores the photochemical synthesis of noble metal nanoparticles, specifically gold (Au) and silver (Ag) nanoparticles, using a one-component photoinitiator system. The synthesis process involves visible light irradiation at a wavelength of 419 nm and an intensity of 250 mW/cm2. The radical-generating capabilities of the photoinitiators were evaluated using electron spin resonance (ESR) spectroscopy. The main objective of this study was to investigate how the concentration of metal salts influences the size and distribution of the nanoparticles. Proposed mechanisms for the photochemical formation of nanoparticles through photoinitiated radicals were validated using cyclic voltammetry. The results showed that the concentration of AgNO3 significantly impacted the size of silver nanoparticles, with diameters ranging from 1 to 5 nm at 1 wt% and 3 wt% concentrations, while increasing the concentration to 5 wt% led to an increase in the diameter of silver nanoparticles to 16 nm. When HAuCl4 was used instead of AgNO3, it was found that the average diameters of gold nanoparticles synthesized using both photoinitiators at different concentrations ranged between 1 and 4 nm. The findings suggest that variations in HAuCl4 concentration have minimal impact on the size of gold nanoparticles. The photoproduction of AuNPs was shown to be thermodynamically favorable, with the reduction of HAuCl4 to Au0 having ∆G values of approximately -3.51 and -2.96 eV for photoinitiators A and B, respectively. Furthermore, the photoreduction of Ag+1 to Ag0 was demonstrated to be thermodynamically feasible, with ∆G values of approximately -3.459 and -2.91 eV for photoinitiators A and B, respectively, confirming the effectiveness of the new photoinitiators on the production of nanoparticles. The synthesis of nanoparticles was monitored using UV-vis absorption spectroscopy, and their sizes were determined through particle size analysis of transmission electron microscopy (TEM) images.

Antifungal Activity of Chitosan/Poly(Ethylene Oxide) Blend Electrospun Polymeric Fiber Mat Doped with Metallic Silver Nanoparticles.

In this work, the implementation of advanced functional coatings based on the combination of two compatible nanofabrication techniques such as electrospinning and dip-coating technology have been successfully obtained for the design of antifungal surfaces. In a first step, uniform and beadless electrospun nanofibers of both polyethylene oxide (PEO) and polyethylene (PEO)/chitosan (CS) blend samples have been obtained. In a second step, the dip-coating process has been gradually performed in order to ensure an adequate distribution of silver nanoparticles (AgNPs) within the electrospun polymeric matrix (PEO/CS/AgNPs) by using a chemical reduction synthetic process, denoted as in situ synthesis (ISS). Scanning electron microscopy (SEM) has been used to evaluate the surface morphology of the samples, showing an evolution in average fiber diameter from 157 ± 43 nm (PEO), 124 ± 36 nm (PEO/CS) and 330 ± 106 nm (PEO/CS/AgNPs). Atomic force microscopy (AFM) has been used to evaluate the roughness profile of the samples, indicating that the ISS process induced a smooth roughness surface because a change in the average roughness Ra from 84.5 nm (PEO/CS) up to 38.9 nm (PEO/CS/AgNPs) was observed. The presence of AgNPs within the electrospun fiber mat has been corroborated by UV-Vis spectroscopy thanks to their characteristic optical properties (orange film coloration) associated to the Localized Surface Plasmon Resonance (LSPR) phenomenon by showing an intense absorption band in the visible region at 436 nm. Energy dispersive X-ray (EDX) profile also indicates the existence of a peak located at 3 keV associated to silver. In addition, after doping the electrospun nanofibers with AgNPs, an important change in the wettability with an intrinsic hydrophobic behavior was observed by showing an evolution in the water contact angle value from 23.4° ± 1.3 (PEO/CS) up to 97.7° ± 5.3 (PEO/CS/AgNPs). The evaluation of the antifungal activity of the nanofibrous mats against Pleurotus ostreatus clearly indicates that the presence of AgNPs in the outer surface of the nanofibers produced an important enhancement in the inhibition zone during mycelium growth as well as a better antifungal efficacy after a longer exposure time. Finally, these fabricated electrospun nanofibrous membranes can offer a wide range of potential uses in fields as diverse as biomedicine (antimicrobial against human or plant pathogen fungi) or even in the design of innovative packaging materials for food preservation.

Beyond the Maxwell Garnett approximation for interacting plasmonic nanoparticles: An analytical and numerical study

We revisit the issue of building a precise mixing formula for the effective permittivity of interacting assemblies of plasmonic nanoparticles. More precisely, we reconsider the analytical expressions rendered by the Maxwell Garnett and Torquato et al. approximation formulas and compare them to each other and to a numerical approach based on the boundary element method applied to interacting assemblies of metallic (gold or silver) nanoparticles. For efficient numerical simulations of interacting assemblies of relatively large sizes, we set up an algorithm with adaptive surface meshing that depends on the particle’s position within the assembly. Next, we derive expressions for the resonance frequency of the assembly from the analytical formulas, which are valid for gold and silver particle assemblies embedded in matrices with large optical indices. We then compare the analytical results with our numerical findings. We find that the Maxwell Garnett approximation formula underestimates the resonance wavelength and that its validity range in terms of inclusion fraction strongly depends on the nature of the metal and the embedding matrix. In the case of silver particles embedded in high-permittivity matrices, the Maxwell Garnett formula should only be used for low particle concentrations. Torquato’s formula, on the other hand, which accounts for multipolar interactions and the assembly spatial arrangement, renders a better agreement with the numerical simulations.

Heat transfer analysis of magnetized Cu-Ag-H2O hybrid nanofluid radiative flow over a spinning disk when the exponential heat source and Hall current are substantial: Optimization and sensitivity analysis

The main motive of the instigated mathematical model is to observe the impact of Hall current on the hybrid nanofluid flow over a disk that is rotating. The copper and silver metal nanoparticles have been considered with volume fraction φ1=φ2=0.01(0.01)0.04 and are suspended in water to form the hybrid nanofluid. Diverse characteristics like magnetic field, thermal radiation, and (ESHS) exponential space dependent heat source are incorporated to investigate the nature of the flow. The present mathematical model is initiated with partial derivative equations (PDEs) which are redrafted as ordinary derivative equations (ODEs) with appropriate transformations of similarity. The results are attained through a blend of the Runge-Kutta method, shooting procedure, and the influences of parameters on the flow of nanofluid and hybrid nanofluid are compared and illustrated both as tables and graphs. The present numerical research is unique because by employing a complete quadratic CCD framework using the RSM strategy, the sensitivity and optimization analysis of the heat transmission improvement for the volume fraction, ESHS, and thermal radiation parameters have been performed. The R-squared and adjusted R-Squared are obtained as 100%. The residual graphs and contour diagrams of the same are also shown. The current study establishes that the Hall parameter increases the radial velocity, but it also controls the energy and cross-radial velocity. The rate of heat transmission is increased by thermal radiation even at low levels of ESHS. The rate of heat transmission is more sensitive (0.024670) to the volume fraction of the hybrid nanofluid when ESHS is at an intermediate level. The lowest sensitivity (-1.269967) value towards ESHS is observed For thermal radiation and ESHS parameter values, the heat transmission rate of the mono nanofluid is not as great as that of hybrid nanofluid. The current study finds applications in the generation of hydroelectric power, air cleansing and rotating equipment, healthcare devices, and many other industries.