Diameter Of Nanoparticles Research Articles

Electrochemical studies of ytterbium doped Cu/Co nanoparticles synthesized by green fabrication using Callistemon viminalis leaves extract

AbstractBACKGROUNDUtilization of phytochemicals for the preparation of metal oxides nanocomposites has been proven to be a best alternate of chemical synthesis methods. Here, we have extracted, isolated and characterized the phytochemicals of Callistemon viminalis plant extract and utilized them as biofuel in the synthesis of Cu/Co and doped Cu/Co nanoparticles. Callistemon viminalis has been shown to have reducing and stabilizing properties. The plant extracts contain a variety of bioactive substances, including tannins, vitamins, amino acids, saponins, inositol, alkaloids, flavonoids, and terpenes. The use of plant extracts in the synthesis of NPs is a quick, dependable, nontoxic, benign, environmentally friendly, and cost‐effective method. Thus, in the present work, the Callistemon viminalis leaves extract a synthesis of Cu/Co nanoparticles and ytterbium doped Cu/Co nanoparticles, and these nanoparticles were characterized by optical properties (UV), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X‐rays diffraction (XRD), and electrochemical application.RESULTSSynthesis of Cu/Co nanoparticles and ytterbium doped Cu/Co nanoparticles at room temperature have been successfully done using Callistemon viminalis aqueous leaf extract. Products were confirmed by conducting UV‐ visible spectrophotometry, FTIR, SEM, and XRD confirming the formation of cubic shaped Cu/Co nanoparticles of average diameter of 14 nm. The aqueous leaf extract acted as a capping agent and the existence of organic functional groups were confirmed by FTIR. Upon varying the Yb content in Cu/Co, the particle's size obtained from SEM showed a decrease in size. The band gap energies were also reduced with Yb doping. The stability of the produced NPs was investigated using linear sweep voltammetry LSV on this special and innovative metal oxide electrode. The LSV analysis has shown an elevation in the scan rate detection with an increase in voltage. 55.6 μA current was detected at 10 V for Cu/Co NPs. Ytterbium doped nanoparticles have shown 471.3 μ current voltage value at scan rate of 10 V. Observed value of current of synthesized Cu/Co NPs was 5.7 μA and the observed current of doped Yb(Cu/Co) was 12.5 μA. The increase in current values of dopant Cu/Co nanoparticles is due to the higher pore volume and surface area of copper, which promotes the transfer of electrons, so the current density is greater of the doped material than the composite NPs. The electrical resistivity of Cu/Co nanoparticles has shown a decline with elevation in current indicating its semiconducting nature.CONCLUSIONIn summary, biologically synthesized Cu/Co and ytterbium doped Cu/Co nanoparticles at room temperature have been successfully synthesized based on the greener approach using Callistemon viminalis aqueous leaf extract. The utilization of the Callistemon viminalis plant‐mediated approach, which makes the procedure more affordable and environmentally benign than chemical synthesis, is one of the study's major contributions. © 2024 Society of Chemical Industry (SCI).

Preparation of Silver Nanoparticles in a Water-in-Oil Microemulsion Stabilized by Ecosurf EH3 and Determination of Their Electrophoretic Mobility.

This work describes a study on the electrophoresis of silver nanoparticles in reverse microemulsions with varying water content. The microemulsion was stabilized using a nonionic ethoxylated surfactant, 2-ethylhexanol triethoxylate (Ecosurf EH3). This study represents the second example of electrophoresis research conducted in media with a low dielectric constant for etoxylated surfactants. The study also determined the boundaries of thermodynamic stability and the conditions required to obtain nanoparticles with a high yield. The hydrodynamic diameter and electrophoretic mobility of nanoparticles were measured using dynamic light scattering and laser Doppler electrophoresis. The study determined the boundary conditions for applying these methods to laser-absorbing samples. The electrophoretic mobility of nanoparticles was found to be dependent on the fraction of water in the range of 2-5%vol. (equivalent to a metal content of 10-25mM), as determined by electrophoresis in a free medium. The increase in volume fraction of water leads to agglomeration of micelles, which causes a decrease in the electrokinetic potential of nanoparticles, likely due to the blurring of the diffuse part of the electrical double layer.

Indium-Iron Oxide Nanosized Solid Solutions as Photocatalysts for the Degradation of Pollutants under Visible Radiation.

A series of solid solutions of indium and iron oxides with different In/Fe ratios (InxFeyO3, with x + y = 2) were synthesized in the form of nanoparticles (diameter of ca. 30-40 nm) with the purpose of generating enhanced photocatalysts with an intermediate band gap compared to those of the monometallic oxides, In2O3 and Fe2O3. The materials were prepared by co-precipitation from an aqueous solution of iron and indium nitrates and extensively characterized with a combination of techniques. XRD analysis proved the formation of the desired InxFeyO3 solid solutions for Fe content in the range 5-25 mol%. UV-Vis absorption analysis showed that the substitution of In with Fe in the crystalline structure led to the anticipated gradual decrease of the band gap values compared to In2O3. The obtained semiconductors were tested as photocatalysts for the degradation of model organic pollutants (phenol and methylene blue) in water. Among the InxFeyO3 solid solutions, In1.7Fe0.3O3 displayed the highest photocatalytic activity in the degradation of the selected probe molecules under UV and visible radiation. Remarkably, In1.7Fe0.3O3 showed a significantly enhanced activity under visible light compared to monometallic indium oxide and iron oxide, and to the benchmark TiO2 P25. This demonstrates that our strategy consisting in engineering the band gap by tuning the composition of InxFeyO3 solid solutions was successful in improving the photocatalytic performance under visible light. Additionally, In1.7Fe0.3O3 fully retained its photocatalytic activity upon reuse in four consecutive cycles.

Probing trade-off between critical size and velocity in cold-pray: An atomistic simulation

The detailed mechanism of bonding in the cold spray process has remained elusive for both experimental and theoretical parties. Adiabatic shear instability and hydrodynamic plasticity models have been so far the most popular explanations. Here, using molecular dynamics simulation, we investigate their validity at the nanoscale. The present study has potential applications in the fabrication of ultrathin layers in the electronics industry. For this aim, we considered Ti nanoparticles of different diameters and Si substrates of different orientations. It is shown that very high spray velocities are required for a jet to be observed at the nanoscale. We propose a method for thermostating the substrate that enables utilizing high spray velocities. For the first time, we demonstrate an oscillatory behavior in both the normal and radial stress components within the substrate that can propagate into the particle. We have shown that neither the adiabatic shear instability model nor the hydrodynamic plasticity model can be ignored at the nanoscale. In addition, the formation of a low-resistance titanium silicide proper for electronic application is illustrated.

Biogenically synthesized gold nanocarrier ameliorated antiproliferative and apoptotic efficacy of doxorubicin against lung cancer

IntroductionConventional chemotherapy treatment is commonly linked to significant side effects due to high therapeutic doses. In this regard, nanoformulations with chemotherapeutic medications hold promise in enhancing drug effectiveness through the reduction of therapeutic dosages, thereby mitigating the potential for adverse side effects. Because of numerous applications in the biomedical arena, there has been a rising interest in developing an environmentally acceptable, long-lasting, and affordable technique for the production of gold nanoparticles. In this particular context, the incorporation of plant extracts in the production of metallic nanoparticles has garnered the interest of numerous scholars. Here, we report the synthesis of gold particles by the green method using Cannabis sativa L. leaf extract and their conjugation with doxorubicin.MethodsThe gold nanoparticles were synthesized by using Cannabis sativa extract and were characterized with various biophysical techniques. Subsequently, gold nanoparticles were conjugated with doxorubicin and their efficacy was tested on A549 cells.Results and DiscussionThe biogenic synthesis of gold nanoparticles was ascertained through an absorption peak at a wavelength of 524 nm, and it was shifted to 527 nm when conjugated with doxorubicin. Nanoparticles were found to be stable exhibiting a zeta potential value of −20.1 mV, and it changed to −12.7 mV when loaded with doxorubicin. The hydrodynamic diameter of nanoparticles was determined to be 45.64 nm and it was increased to 58.95 nm when conjugated with the drug. The average size of nanoparticles analyzed by TEM was found to be approximately 17.2 nm, while it was 23.5 nm in the case of drug-nanoconjugate. Moreover, there was a significant amelioration in the antiproliferative potential of doxorubicin against lung cancer A549 cells when delivered with gold nanocarrier, which was evident by the lower IC50 and IC75 values of drug-nanoconjugates in comparison to drug alone. Furthermore, the inhibitory effect of drug-nanoconjugates and drug alone was characterized by alteration in the cell morphology, nuclear condensation, increased production of reactive oxygen species, abrogation of mitochondrial membrane potential, and enhanced caspase activities in A549 cells. In sum, our results suggested enhanced efficacy of doxorubicin-gold nanoconjugates, indicating effective delivery of doxorubicin inside the cell by gold nanoparticles.

Size-Dependent Electrostatic Adsorption of Polymer-Grafted Gold Nanoparticles on Polyelectrolyte Brushes.

Designing a functional surface that selectively adsorbs nanoparticles based on their size and shape is essential for developing an advanced adsorption-based, postsynthesis nanoparticle separation device. We demonstrate selective adsorption of larger nanoparticles from solution onto a polyelectrolyte brush by tuning the salt concentration. Specifically, a positively charged polyelectrolyte brush is created by converting pyridine groups of poly(2-vinylpyridine) to n-methylpyridinium groups using methyl iodide. The adsorption kinetics and thermodynamics of poly(ethylene glycol)-grafted, negatively charged gold nanoparticles (diameters of 12 and 20 nm) were monitored as a function of salt concentration. In a salt-free solution, the polyelectrolyte brush adsorbs gold nanoparticles of both sizes. As the salinity increases, the areal number density of adsorbed nanoparticles monotonically decreases and becomes negligible at high salinity. Interestingly, there is an intermediate range of salt concentrations (i.e., 15-20 mM of NaCl) where the decrease in nanoparticle adsorption is more pronounced for smaller particles, leading to size-selective adsorption of the larger nanoparticles. As a further demonstration of selectivity, the polyelectrolyte brush is immersed in a binary mixture of 12 and 20 nm nanoparticles and found to selectively capture larger particles with ∼90% selectivity. In addition, the size distribution of as-synthesized gold nanoparticles, with an average diameter of 12 nm, was reduced by selectively removing larger particles by exposing the solution to polyelectrolyte brush surfaces. This study demonstrates the potential of a polyelectrolyte brush separation device to remove larger nanoparticles by controlling electrostatic interactions between polymer brushes and particles.

New Parameter for Benchmarking Plasmonic Gas Sensors Demonstrated with Densely Packed Au Nanoparticle Layers.

Localized surface plasmon resonance (LSPR) gas sensitivity is introduced as a new parameter to evaluate the performance of plasmonic gas sensors. A model is proposed to consider the plasmonic sensors' surface sensitivity and plasmon decay length and correlate the LSPR response, measured upon gas exchange, with an equivalent refractive index change consistent with adsorbed gas layers. To demonstrate the applicability of this new parameter, ellipsoidal gold nanoparticles (NPs) arranged in densely packed hexagonal lattices were fabricated. The main advantages of these sensors are the small and tunable interparticle gaps (18-29 nm) between nanoparticles (diameters: 72-88 nm), with their robust and scalable fabrication technology that allows the well-ordered arrangement to be maintained on a large (cm2 range) area. The LSPR response of the sensors was tested using an LSPR sensing system by switching the gas atmosphere between inorganic gases, namely He/Ar and Ar/CO2, at constant pressure and room temperature. It was shown that this newly proposed parameter can be generally used for benchmarking plasmonic gas sensors and is independent of the type and pressure of the tested gases for a sensor structure. Furthermore, it resolves the apparent disagreement when comparing the response of plasmonic sensors tested in liquids and gases.

Effects of Silica Nanoparticles on the Piezoelectro-Elastic Response of PZT-7A-Polyimide Nanocomposites: Micromechanics Modeling Technique.

By using piezoelectric materials, it is possible to convert clean and renewable energy sources into electrical energy. In this paper, the effect on the piezoelectro-elastic response of piezoelectric-fiber-reinforced nanocomposites by adding silica nanoparticles into the polyimide matrix is investigated by a micromechanical method. First, the Ji and Mori-Tanaka models are used to calculate the properties of the nanoscale silica-filled polymer. The nanoparticle agglomeration and silica-polymer interphase are considered in the micromechanical modeling. Then, considering the filled polymer as the matrix and the piezoelectric fiber as the reinforcement, the Mori-Tanaka model is used to estimate the elastic and piezoelectric constants of the piezoelectric fibrous nanocomposites. It was found that adding silica nanoparticles into the polymer improves the elastic and piezoelectric properties of the piezoelectric fibrous nanocomposites. When the fiber volume fraction is 60%, the nanocomposite with the 3% silica-filled polyimide exhibits 39%, 31.8%, and 37% improvements in the transverse Young's modulus ET, transverse shear modulus GTL, and piezoelectric coefficient e31 in comparison with the composite without nanoparticles. Furthermore, the piezoelectro-elastic properties such as ET, GTL, and e31 can be improved as the nanoparticle diameter decreases. However, the elastic and piezoelectric constants of the piezoelectric fibrous nanocomposites decrease once the nanoparticles are agglomerated in the polymer matrix. A thick interphase with a high stiffness enhances the nanocomposite's piezoelectro-elastic performance. Also, the influence of volume fractions of the silica nanoparticles and piezoelectric fibers on the nanocomposite properties is studied.

Ultrapure gold recovery from electronic waste as nanoparticles immobilized in hydrogel matrix

Solid-supported gold nanoparticles possess significant value as economical and eco-friendly catalysts due to their durability and reusability. Conventional methods to synthesize heterogeneous catalysts require the use of expensive gold precursors, diminishing their economic viability. Recovering gold directly as nanoparticles immobilized in a solid matrix from electronic waste (e-waste) provides a promising economic solution. However, the greater abundance of other metal ions in e-waste solutions makes this task challenging, demanding more selective approaches. This study presents a cost-effective one-pot synthesis of gold nanoparticles immobilized in a hydrogel matrix from e-waste solutions, circumventing the need for gold precursors. The fabricated hydrogel exhibits exceptionally selective gold reduction, producing well-distributed and highly pure (23.78 K) gold nanoparticles inside the hydrogel matrix. The fine control in nanoparticle diameters from 22 to 35 nm was achieved by tuning the monomer compositions of the hydrogel. These hydrogel-supported gold nanoparticles demonstrate reusable catalytic properties, indicating their potential sustainability and industrial compatibility. This approach addresses the economic challenges of synthesizing solid-supported gold nanoparticles and offers a sustainable pathway.

A comparative analysis on the dynamics of solid-liquid interfacial layer and nanoparticle diameter of magnetohydrodynamic nanofluid flow containing spherical and cylindrical-shaped alumina nanoparticles over a stretching curved surface

In this work, a comparative analysis on magnetohydrodynamic nanofluid flow containing spherical and cylindrical-shaped alumina nanoparticles over a stretching curved surface is mainly focused. The effects of Brownian motion, Joule heating, thermophoresis, chemical reaction and activation energy are taken into consideration in this work. It is important to mention that this analysis considers a 4 % volume fraction of the alumina nanoparticles. A thermal convective and zero-mass flux conditions are imposed to scrutinize the heat transfer analysis. The leading equations are transformed into dimensionless form by using suitable similarity variables. A numerical solution is obtained using the shooting technique. The acquired outcomes depict that greater magnetic factor enhances the skin friction coefficient. The greater magnetic factor, thermal Biot number, Eckert number, and interfacial layer thickness augment the heat transfer rate, while a greater nanoparticle diameter diminishes the thermal transfer rate. A higher magnetic factor has an increasing impact on thermal distribution and a reducing impact on velocity distribution. A greater curvature factor enhances both the velocity and thermal distributions. The concentration distribution is enhanced by the higher interfacial layer thickness and activation energy factor, while it is reduced by a higher nanoparticle diameter, Brownian motion factor, and chemical reaction factor. From the comparative analysis, it is found that the velocity, thermal, and concentration distributions are higher for the cylindrical-shaped nanoparticles compared to spherical-shaped nanoparticles.

Roll-to-Roll Manufactured Polyetherimide Nanocomposite With Different Diameters of SiO2 Nanoparticles Exhibiting Improved High-Temperature Dielectric Energy Storage Performance.

To enhance the high-temperature energy storage performance of the polymer-based dielectric film, inorganic nanofillers with large band gaps are much more effective and have been widely adopted. However, the impact of nanoparticle diameters on the dielectric properties of polymer nanocomposites has been less studied. Herein, silicon dioxide nanoparticles (SiO2-NPs)with varying diameters (20, 60, 120, 200nm) prepared by the sol-gel method are incorporated in the PEI matrix to form PEI/SiO2 nanocomposites. The characterization results reveal a distinct correlation between the dielectric properties of polyetherimide (PEI) composites and the diameters of SiO2-NPs. Leakage current density analysis and breakdown strength simulations indicate that SiO2-NPs with smaller diameters generate more deep traps that impede the transport of charge carriers, especially under high temperatures. Notably, PEI/20nm-SiO2 exhibits a high discharged energy density of 4.4 J cm-3 with an efficiency of 90% at 150°C. Furthermore, PEI/SiO2 films with 10µm in thickness are manufactured by a large-scale solution casting process. The continuously prepared PEI/20nm-SiO2 film exhibits a discharged energy density of 3.2 J cm-3 with an efficiency of 90% at 150°C. This study not only provides a strategy for the design of high-performance dielectric polymer composites but also offers a large-scale high-temperature dielectric film for practical use.

Bimetallic AgCo Nanoparticle Synthesis via Combinatorial Nanosecond Laser‐Induced Dewetting of Thin Films

Herein, a combinatorial approach is developed to conduct high‐throughput studies on the nanosecond pulsed laser‐induced dewetting phenomenon of bilayer Ag–Co metallic thin films. Laser irradiation results in the spontaneous rupture of these films in nanosecond timescale, forming bimetallic nanoparticles (NPs) through intermediate stages of hole formation and bicontinuous nanostructures. This approach utilizes bilayer thin films with thickness gradients in both Ag and Co layers (referred to as bigradient samples) while maintaining a constant overall thickness. The laser irradiation on such bigradient bilayer films facilitates control on Ag and Co ratio in the thin films, thus enabling material libraries of Ag–Co NPs covering a large compositional variation. The evolution of NPs with a correlation between NP diameter and interparticle spacings is further studied. The study reveals monotonic increase in NP size and interparticle spacing in Co/Ag bilayer arrangement, while an increase and subsequent decrease in the NP size is observed at 50% Ag in Ag/Co bigradient films. A transition from intermediate stage hole formation to bicontinuous nanostructures with changing composition is also observed. These changes in intermediate stage morphologies and dewetting mechanism are attributed to variation of the free energy of the bilayer system dominated by intermolecular interaction forces.

Oppositely charged polymer-surfactant nanoparticles stabilized by triblock copolymers for enhanced oil loading

When oppositely charged polymers and surfactants combine, they can form a concentrated phase rich in micelles interconnected by polymer chains. Dispersing this concentrated phase as nanoparticles in an aqueous media can be a way to load and deliver hydrophobic ingredients. This study employed triblock copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), EOxPOyEOx, also known as poloxamers or pluronics, to disperse the concentrated phase, forming nanoparticles of aggregated micelles connected by the polyion chains. We showed that nanoparticles formed by hexadecyltrimethylammonium bromide (CTAB), poly(acrylic acid) (PAA), and different EOxPOyEOx copolymers can enhance the loading of oily ingredients compared to pure surfactant micelles. Dispersions with 1.6 wt% of nanoparticles exhibited water-like viscosity and loaded up to 0.48 wt% of oil. Characterization techniques, including dynamic light scattering (DLS), electrophoretic mobility, small-angle X-ray scattering (SAXS), and cryogenic transmission electronic microscopy (cryo-TEM), revealed positively charged spherical 50–180 nm nanoparticles with a core formed by concentrated micelles, that were stable for at least 4 months. Variations in the EO and PO block lengths did not impact morphology, showing that different EOxPOyEOx copolymers were suitable for dispersing the nanoparticles. Increasing EO block length size decreased the diameter of nanoparticles and enhanced stability, providing a means to control their properties. In conclusion, nanoparticles formed by oppositely charged polymer-surfactant mixtures and stabilized by triblock copolymers showed potential for applications, such as sprays, due to their effective oil loading, high stability, and facile preparation.

Investigation of magnetocapacitance and magnetoconductivity in single-phase Y-Type hexaferrite Ba2Co2Fe12O22 nanoparticles

This research paper examines the synthesis and characterization of Y-type hexaferrite Ba2Co2Fe12O22 nanoparticles produced using the sol-gel method. The study explores their structural, magnetic, and electrical properties, confirming the successful synthesis of pure-phase hexaferrites with a hexagonal structure at an annealing temperature of 1150 °C. Morphological analysis reveals changes in nanoparticle diameter based on varying annealing temperatures. The Ba2Co2Fe12O22 nanoparticles display soft ferrimagnetism, achieving a peak saturation magnetization of 52.31 emu/g at 1150 °C, along with notable magnetocrystalline anisotropy and anisotropy field. Investigations on magnetocapacitance and magnetoconductivity under magnetic fields revealed improved performance, with high magnetocapacitance (MC%) and magnetoconductivity (MσAC%) percentages of 24 % and 21 %, respectively. This suggests the potential utility of these nanoparticles in applications such as permanent magnets, magnetic recording media, and spintronic devices.

Statistical and numerical analysis of magnetic field effects on laminar natural convection heat transfer of nanofluid in a hexagonal cavity

This paper presents a statistical and numerical investigation that examines the optimization and sensitivity analysis of the unsteady laminar natural convective heat transfer flow of Fe3O4-water nanofluid in a hexagonal cavity considering the impacts of a sloping magnetic field in one-component nanofluid model. The inclined walls of the cavity are maintained at a constantly low temperature, while the bottom wall is uniformly heated. The upper wall, however, is regarded as adiabatic. The nanofluid thermal conductivity model incorporates the impact of Brownian motion. The Galerkin weighted residual finite element method has been employed to solve the governing dimensionless equations. The results are provided regarding the average Nu, streamlines, and isotherms. The study uses response surface methodology to analyze the sensitivity of parameters such as the Ha, Ra, and nanoparticle volume percentage. Using a response surface policy allows for optimizing the process and identifying the most favorable circumstances to achieve the maximum thermal transfer rate. The flow pattern of the nanofluid is significantly affected by the magnetic field and its alignment. The numerical results indicate a significant rise in the average Nu as the nanoparticle volume percentage, magnetic field inclination angle, nanoparticle type factor, and Ra increase. Conversely, the Hartmann number and the nanoparticle's diameter have contrasting effects. When considering Brownian motion, the average Nu grows by 225.89 % for Ra = 106 with ϕ = 0.03 and 25.28 % for the other case. The optimal condition for heat transfer occurs when Ra = 106, Ha = 4, and ϕ =0.03 while keeping the other parameters constant.

Fabrication and detection characteristics evaluation of SnO2@WO3 film as an effective NO2 gas sensor

In this article, tin oxide (SnO2) doped tungsten oxide (WO3) was deposited on Si substrate as an effective NO2 gas sensor via pulsed laser deposition (PLD) considering different content of SnO2 to WO3. Further, the correlation between the investigated microstructural and sensing characteristics was thoroughly elaborated. Specifically, an increment in the SnO2 content from 10:90 to 30:70 % resulted in smaller nanoparticle diameter (53.9–45.9 nm); the attained energy bandgap exhibited an inverse profile along considerably high electrical resistance alteration. In detail, the gas response increased from 30.7 to 39.5 for the addressed SnO2 to WO3 contents, respectively. The examined operating temperature indicated a negative correlation along the evaluated sensing profile with R2 value of −0.98. The time-resolved characteristics of the optimum gas sensor (@30:70) revealed rise/fall time of 6 and 13 sec. at 150 °C, respectively; this was found to be pronouncedly higher at higher operating temperatures.

FeVO4 nanoparticles for N-Alkylation of acetamides under blue light irradiation: Mechanistic insights and product characterization

This study aimed to synthesize FeVO4 nanoparticles using a wet-chemical approach. The nanoparticles were characterized and confirmed using various techniques. XRD (X-Ray Diffraction) confirmed the triclinic crystal system of the nanoparticles, and the crystallite size was calculated to be 33.5 nm. FE-SEM (Field Emission Scanning Electron) and HR-TEM (High- Resolution Transmission Electron Microscopy) confirmed the spherical nature of FeVO4 with particle size of 41.8 nm. Further SAED (Selected Area Electron Diffraction) confirmed the crystallinity nature of the nanoparticles. Optical studies and EIS (Electrochemical Impedance Spectroscopy) revealed their photocatalytic behavior. The pore volume and diameter of the FeVO4 nanoparticles were 0.024 and 2.102 nm, respectively. The obtained nanoparticles were employed as photocatalysts for the N-alkylation of N-phenyl and N-pyridinyl acetamides under blue LED light. The reaction progressed well in approximately 8–12 h with a yield of 60–90 %. The photocatalytic evaluation was optimized under various conditions and provided with mechanistic investigations. The novel N-alkylated analogues were verified by FT-IR, 1H NMR, 13C NMR, and HRMS. The present work explores a novel approach to N-alkylation using FeVO4 nanoparticles in an effective manner. This may lead to new advancements in FeVO4 based photocatalysts for numerous organic transformations.

Low Silver/Copper Exchange in a Copper-Phosphate Enzyme Nanoflower Hybrid Extremely Enhanced Antimicrobial Efficacy against Multidrug Resistant Bacteria.

Infections caused by bacteria that are resistant to many drugs are a major threat to public health in many countries around the world. Here we demonstrate the creation of heterogeneous catalytic nanomaterials with outstanding antimicrobial properties against several superbugs. We have shown that replacing a small amount of copper in a generated copper-phosphate-enzyme nanoflower hybrid with silver drastically increases the antimicrobial capacity of the nanomaterial. In this sense, it has been confirmed that the exchange generated silver phosphate nanoparticles on the Cu nanoflowers, with control of the nanoparticle diameter size. The Fenton catalytic activity of the Ag-containing nanobiohybrids was affected, showing better performance with lower amounts of silver in the final hybrid. This effect was confirmed by their antimicrobial efficacy against Escherichia coli, where the Ag4Cu32@CALB hybrid displayed a log reduction of 3.9, an efficiency more than 5000 times higher than that obtained with copper nanoflowers (Cu36@CALB). The hybrid also showed excellent efficacy against other bacteria such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Mycobacterium smegmatis with log reductions of 7.6, 4.3, and 1.8, respectively.

Effect of particle size on SiO2 nanofluid viscosity determined by a two-step method

AbstractAccording to review of the literature, the influence of nanoparticle diameter with irregular shapes on viscosity requires further research since there is no relation between particle size and nanofluid stability. In this study, SiO2/EG–water-based nanofluid samples were prepared, and their viscosities were experimentally determined. SiO2 nanoparticles had sizes of 7, 15, and 40 nm, and the base fluid was a 50% ethylene glycol and 50% water mixture. Nanofluid samples were prepared using a two-step technique. Viscosity change was measured every 10 °C from 20 to 60 °C. The maximum viscosity values were observed for 7, 15, and 40 nm particles over an entire concentration range. Considering all measurements, the highest viscosity increase was 60.51% for 3% SiO2 (7 nm) at 60 °C, and the lowest viscosity change was 7.72% for 1% SiO2 (40 nm) at 40 °C. The most stable sample of the current study was 1% SiO2 (15 nm), and its Zeta potential was − 35.6 mV. Finally, a new empirical equation that included temperature, particle diameter, and concentration terms is suggested to predict dynamic viscosity, with R adj 2 = 0.98. It was also compared with previous correlations.

Aggregating nanoparticle transport with nonlinear attachment: Modeling and experimental validation

A conceptual mathematical model was developed to simulate the transport of migrating nanoparticles in homogeneous, water saturated, 1-dimensional porous media. The model assumes that nanoparticles can collide with each other and aggregate. Nanoparticles can be found attached reversibly and/or irreversibly onto the solid matrix of the aquifer or suspended in aqueous phase. Attached particles may either contribute to the acceleration of subsequent particle deposition or hinder it, leading to the ripening or blocking process, respectively. The aggregation process was simulated based on the Smoluchowski Population Balance Equation (PBE) and was coupled with the advection-dispersion-attachment equation (ADA) to form a family of partial differential equations that govern the migration of nanoparticles in porous media. For the solution of the PBE, an efficient finite volume solver was employed that significantly accelerated computation times, by reducing the number of participating equations, while maintaining the required accuracy. The developed model was applied to nanoparticle transport experimental data available in literature. The model successfully matched the breakthrough concentration curves, and estimated the corresponding nanoparticle diameter, proving its ability to capture the physical processes participating in nanoparticle transport.