Average Size Of Nanoparticles Research Articles

Characterizing bubble interaction effects in synchronous-double-pulse laser ablation for enhanced nanoparticle synthesis

To further advance nanomaterial applications and reduce waste production during synthesis, greener and sustainable production methods are necessary. Pulsed laser ablation in liquid (PLAL) is a green technique that enables the synthesis of nanoparticles. This study uses synchronous-double-pulse PLAL to understand bubble interaction effects on the nanoparticle size. By adjusting the lateral separation of the pulses relative to the maximum bubble size, an inter-pulse separation is identified where the nanoparticle size is fourfold. The cavitation bubble pair interaction is recorded using a unique coaxial diffuse shadowgraphy system. This system allows us to record the bubble pair interaction from the top and side, enabling the identification of the bubble’s morphology, lifetime, volumetric, and displacement velocity. It is found that the collision and collapse of the bubbles generated at a certain inter-pulse separation results in a larger nanoparticle size. These results mark a significant advancement by controlling the abundance of larger nanoparticles in PLAL, where previous efforts were primarily focused on reducing the average nanoparticle size. The experimentally observed trends are confirmed by numerical simulations with high spatial and temporal resolution. This study serves as a starting point to bridge the gap between upscaled multi-bubble practices and fundamental knowledge concerning the determinants that define the final nanoparticle size.

Synthesis and characterization of magnesium zinc ferrite nanoparticles for catalytic hydrogen evolution

We have prepared Mg1-xZnxFe2O4 nanoparticles (x values varying from 0.0 to 0.8 by 0.2 increments) for use as catalysts for hydrogen production in the methanolysis of sodium borohydride (NaBH4). The catalytic performance of the Mg1-xZnxFe2O4 nanoparticles with different zinc content for hydrogen production were evaluated in the methanolysis of NaBH4 inside glass vessels. Different characterization techniques were used to analyse the prepared nanoparticles such as X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), Field Emission Scanning Electron Microscope (FESEM), Transmission Electron microscopy (TEM), and Scanning Transmission Electron microscopy STEM. The average size of Mg1-xZnxFe2O4 nanoparticles was 10 nm. The largest energy band gap value was 4.77 eV for MgFe2O4 nanoparticles, while the lowest value was 2.89 eV for Mg0.2Zn0.8Fe2O4 nanoparticles. Mg0.8Zn0.2Fe2O4 nanoparticles were proven as the catalysts with the highest hydrogeneration rate with a value of 15,957 mL min−1 g−1.

Chitosan nanoparticles-based in vivo delivery of miR-155 modulates the Viral haemorrhagic septicaemia virus-induced antiviral immune responses in zebrafish (Danio rerio)

Viral haemorrhagic septicaemia virus (VHSV) is one of the highly pathogenic virus, which causes viral haemorrhagic septicaemia disease in both marine and freshwater fish. Micro RNA-155 (miRNA-155) is a multifunctional small non-coding RNA and it involves regulation of immune responses during viral infection. In this study, dre-miR-155 mimics were encapsulated into chitosan nanoparticles (CNPs). Resulted encapsulated product (miR-155-CNPs) was investigated for its immunomodulation role in zebrafish during experimentally challenged VHSV infection. Successful encapsulation of dre-miR-155 mimics into CNPs was confirmed through average nanoparticle (NPs) size (341.45 ± 10.00 nm), increased encapsulation efficiency percentage (98.80%), bound dre-miR-155 with chitosan, sustained release in vitro (up to 40%), and the integrity of RNA. Overexpressed miR-155 was observed in gills, muscle, and kidney tissues (5.42, 19.62, and 140.72-folds, respectively) after intraperitoneal delivery of miR-155-CNPs into zebrafish upon VHSV infection (miR-155-CNPs + VHSV). The miR-155-CNPs + VHSV infected fish had the highest cumulative survival (85%), which was associated with low viral copy numbers. The miR-155-overexpressing fish showed significantly decreased expression of ifnγ, irf2bpl, irf9, socs1a, il10, and caspase3, compared to that of the miR-155 inhibitor + VHSV infected fish group. In contrast, il1β, tnfα, il6, cd8a, and p53 expressions were upregulated in miR-155-overexpressed zebrafish compared to that of the control. The overall findings indicate the successful delivery of dre-miR-155 through miR-155-CNPs that enabled restriction of VHSV infection in zebrafish presumably by modulating immune gene expression.

Intensifying levulinic acid hydrogenation using mechanochemically prepared copper on manganese oxide catalysts

A series of copper nanoparticles supported on manganese oxide octahedral molecular sieves (OMS-2) were prepared using mechanochemical (Ball-Mill) and conventional wet-impregnation (Wet-Imp) methods. All catalysts prepared were thoroughly characterized using ICP-OES elemental analysis, X-ray diffraction (XRD), N2 sorption, H2 temperature programmed reduction (TPR) and transmission electron microscopy (TEM) techniques. The catalyst preparation methods greatly affected the size of the Cu nanoparticles. TEM images showed that 5 wt% Cu/OMS-2 (Ball-Mill) catalyst had a narrow particle size distribution with an average Cu nanoparticle size of 2.1 nm, while the corresponding 5 wt% Cu/OMS-2 catalyst prepared using wet-impregnation method had an average Cu nanoparticle size of 19.2 nm. The structural features of the catalysts were corelated with the catalytic activity using the liquid phase hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL), as an exemplar process. In LA hydrogenation at 190 °C and 20 bar H2 pressure, the ball milled catalysts achieved higher LA conversion, and greater GVL yield, as compared to the corresponding catalysts prepared by wet-impregnation method, reinforcing that Cu nanoparticle size and metal dispersion are important tool to intensify the catalytic activity. For instance, 5 wt% Cu/OMS-2 (Ball-Mill) catalyst achieved almost twice the turnover frequency (TOF), 24.7 h−1 as compared to the 5 wt% Cu/OMS-2 (Wet-Imp) catalyst, TOF 11.8 h−1, under identical reaction conditions. The results of this study demonstrate that ball milling is a superior method for Cu/OMS-2 catalyst preparation than wet impregnation.

Green Synthesis of Copper Oxide Nanoparticles from the Leaves of Aegle marmelos and Their Antimicrobial Activity and Photocatalytic Activities.

The leaves of the Aegle marmelos plant were used for the green synthesis of copper oxide nanoparticles and further characterized by different techniques, including (Ultra Violet-Visible) UV-Vis, Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), Transmission electron microscopy (TEM) and X-ray diffraction (XRD). The UV-Vis showed a peak at 330 nm, which may be due to the Surface Plasmon Resonance phenomenon. XRD analysis showed the crystalline nature of copper oxide nanoparticles (CuO NPs). In contrast, SEM showed that nanoparticles were not aggregated or clumped, EDX showed the presence of elemental copper., and further, the TEM analysis revealed the average particle size of copper oxide nanoparticles to be 32 nm. The Minimum Inhibitory Concentration (MIC) for Escherichia coli (E. coli) and Staphylococcusaureus (S. aureus) was found to be 400 µg/mL, whereas for Candida albicans (C. albicans) and Candida dubliniensis (C. dubliniensis) it was 800 µg/mL. The zone of inhibition in the well diffusion assay showed the antimicrobial activity of copper oxide nanoparticles, and it also showed that as the concentration of copper oxide nanoparticles increased, the zone of inhibition also increased. Further, the electron microscopic view of the interaction between copper oxide nanoparticles and C. albicans cells showed that CuO NPs were internalized and attached to the cell membrane, which caused changes in the cellular structure and caused deformities which eventually led to cell death. The prepared CuO NPs showed significant photocatalytic degradation of organic dyes in the presence of sunlight.

In situ synthesis and stabilization of PVP-coated aluminum nanoparticles by one-step pulsed laser ablation in liquid: Investigation and quantification of PVP coverage effects

This study explored the use of one-step pulsed laser ablation (PLA) in liquid process for in situ synthesis of polyvinylpyrrolidone (PVP) coated highly-stabilized Al nanoparticles (NPs). The effect of different process variables such as laser energy, PVP concentration, and PVP chain length on the composition, size, distribution, and stability of the synthesized NPs was investigated. The results showed that adding PVP to the solution led to smaller average size of NPs with a more uniform distribution, and enhanced resistance to aggregation. This study also revealed that while PVP only partially inhibited the reaction between Al NPs and oxygen during NP generation, it could provide excellent blocking performance against hydroxylation to NPs in subsequent aging experiments. The concept of polymer coverage was introduced to quantify the protective effect of PVP polymers on Al NPs. At 0.1 J laser energy and a K-30 PVP concentration of 10 g/L, a polymer coverage value of 6773 was achieved, maximizing the amount of polymer per unit NP surface area. It was verified that Al NPs' reactivity was most efficiently suppressed under this condition. However, it was observed that the critical polymer coverage value required to suppress the reaction of Al NPs with their surroundings depended on process variables such as laser energy and polymer chain length. This study also confirmed that using high molecular weight polymers can further improve the anti-agglomeration performance and ablation efficiency while lowering the required critical polymer coverage value.

Experimental Evaluation of Kinetic Characteristics of SiO2@AuNPs Nanocomposite and BSA-stabilized gold Nanoparticles toward Peroxidase-Mediated Reactions

In this study, BSA-stabilized gold nanoparticles and SiO2 @AuNPs nanocomposite were synthesized and then characterized by the TEM imaging method. The average size of BSA-stabilized gold nanoparticles was found to be as small as 13 nm while the SiO2 @AuNPs nanocomposite showed a mean size of 204 nm. The experimental studies revealed that both BSA-stabilized gold nanoparticles and SiO2 @AuNPs nanocomposite exhibit intrinsic peroxidase-like activity. Hence, to explore more precise no their catalytic efficiency and substrate affinity of them, the kinetic characteristics of both nanozymes were quantified using the Menten kinetic model, and the provided results were compared. Upon using TMB as peroxidase substrate, Vmax of 0.022 µM min-1 and a Km of 0.06 mM for the SiO2 @AuNPs nanocomposite was achieved while for the BSA-stabilized gold nanoparticles, a Vmax and Km at about 0.263 μM min-1and 0.03 mM, in order, was estimated. The Vmax of BSA-stabilized gold nanoparticles was 12.0-fold higher than that of SiO2 @AuNPs nanocomposite, revealing that the catalytic efficiency of BSA-stabilized gold nanoparticles is 12.0-fold higher than SiO2 @AuNPs nanocomposite. Besides, the Km value of SiO2 @AuNPs nanocomposite was 2-order higher than that of BSA-stabilized gold nanoparticles, indicating that the substrate affinity toward BSA-stabilized gold nanoparticles is 2.0-order higher than the SiO2 @AuNPs nanocomposite. Since, the active nodes of both nanozymes are same (i.e., gold), the difference between their catalytic efficiency and affinity can be assigned to their different sizes and the ability of the active nodes to bind the substrate. Based on the results of this work, small-size BSA-stabilized gold nanoparticles are characteristically more efficient peroxidase mimic materials than the SiO2 @AuNPs nanocomposite.

Effects of silver nanoparticles prepared by aqueous extract of Ferula communis on the developing mouse embryo after maternal exposure.

Green synthesis of silver nanoparticles (AgNPs) from aqueous silver nitrate has been achieved using an extract of Ferula communis leaf as a capping, reducing, and stabilizing agent. The formation and stability of the green synthesized silver nanoparticles in the colloidal solution were monitored by absorption measurements. Silver nanoparticles were characterized by different analyses such as X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and FT-IR spectroscopy. The average particle size of silver nanoparticles was determined by high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) analyses. In this experiment, pregnant female mice were divided into four groups (G); G1 was the control and received phosphate-buffered saline, G2 received orally aqueous extract of F. communis leaf, G3 received orally AgNPs chemically prepared by NaBH4, and G4 received orally AgNPs prepared by aqueous extract of F. communis leaf. The diameter of AgNPs was 20nm. AgNPs exhibited good catalytic reduction ability toward methyl orange in the presence of sodium borohydride with a rate constant of 2.95 x 10-4 s-1. The results revealed the occurrence of resorbed embryos in G2, G3, and G4 with different percentages. The livers of mothers and embryos at E14.5 in G2, G3, and G4 showed different levels of histopathological alteration and increase in GFAP and CTGF expressions compared with the control group. The study concluded that the oral administration of small-sized AgNPs (20nm) prepared by Ferula extract had less toxicity than those prepared by the chemical method.

Synthesis and investigation of mixed Zn–Ni spinel nanoparticles for microwave applications

Nickel ferrite solid solutions remain one of the main materials for a whole range of applications, including microwave equipment and components, the requirements for parameters and homogeneity of materials are constantly increasing. In this work, Ni1–xZnxFe2O4 nanoparticles with an average diameter of 12.5 nm were successfully synthesized by the microwave-assisted urea method. The temperature of a single-phase product formation was 400 °C, which is lower compared to more common precipitation from aqueous solution methods or solid-state route. Ni1–xZnxFe2O4 materials demonstrate high saturation magnetization and low coercive force. The magnetization changes with increasing Zn concentration and reaches the maximum at x = 0.5. Also, the increase in zinc content leads to an increase in the lattice parameters. The average size of ferrite nanoparticles synthesized by the microwave-assisted urea method is smaller compared to ferrites synthesized earlier by the co-precipitation method. Also, lower treatment temperatures provide higher stoichiometry, and homogeneity of materials while magnetization difference is negligible. These research results provide a general and effective route to synthesize other nanostructures for a variety of microwave components.

Gd2O3 nanoparticles prepared by spark discharge method: Structure and magnetocaloric properties

Several batches of nanoparticles of gadolinium oxide Gd2O3 were obtained by the electrophysical spark discharge (ESD) method using selected variations of the value of the energy supplied to the discharge gap. The change of the charge voltage led to a change in the energy supplied to the discharge gap in the range of 3 J to 55 J. The average size of spark discharge nanoparticles in all cases was close to 8 nm in accordance with low-temperature nitrogen adsorption data. Gd2O3 nanoparticles contained two crystalline phases (cubic and monoclinic), the amount of which varied within certain limits by changing the parameters of the spark discharge. The obtained maximum values of the magnetic entropy change ΔSM of the studied ESD Gd2O3 nanoparticles with a monoclinic phase content of less than 40 wt% are not inferior to the value of ΔSM of Gd2O3 nanoparticles obtained by chemical methods. The spark discharge technique seems to be a promising technology for manufacturing of gadolinium oxide nanoparticles applications for the magnetic cooling systems of cryogenic refrigeration.

Exploring the bioactivity of reduced graphene oxide and TiO2 nanocomposite for the regenerative medicinal applications

Millions of people globally suffer from issues related to chronic wounds due to infection, burn, obesity, and diabetes. Nanocomposite with antibacterial and anti-inflammatory properties is a promising material to promote wound healing. This investigation primarily aims to synthesize reduced graphene oxide and titanium dioxide (rGO@TiO2) nanocomposite for wound healing applications. The rGO@TiO2 nanocomposite was synthesized by the one-step hydrothermal technique, and the physicochemical characterization of synthesized nanocomposite was performed by X-ray diffraction, Fourier transforms infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, and dynamic light scattering. Further, the nanocomposite antibacterial, cytotoxicity, and wound-healing properties were analyzed by disc diffusion method, MTT assay, and in vitro scratch assay, respectively. Based on the TEM images, the average particle size of TiO2 nanoparticles was around 9.26 ± 1.83 nm. The characteristics peak of Ti–O–Ti bonds was observed between 500 and 850 cm−1 in the Fourier transforms infrared spectrum. The Raman spectrum of graphene oxide (GO) was obtained for bands D and G at 1354 cm−1 and at 1593 cm−1, respectively. This GO peak intensity was reduced in rGO, revealing the oxygen functional group reduction. Moreover, the rGO@TiO2 nanocomposite exhibited dose-dependent antibacterial properties against the positive and negative bacterium. The cytotoxicity for 5–100 µg/mL of rGO@TiO2 nanocomposite was above the half-maximal inhibitory concentration value. The in vitro scratch assay for rGO@TiO2 indicates that the nanocomposite promotes cell proliferation and migration. The nanocomposite recovered the wound within 48 h. The rGO@TiO2 nanocomposite shows potential materials for wound healing applications.

Green synthesis of silver nanoparticles using Sambucus ebulus leaves extract: Characterization, quantitative analysis of bioactive molecules, antioxidant and antibacterial activities

Sambucus ebulus is a well-known medicinal plant used as a traditional medicine due to its bioactive compound contents. The importance of nanotechnology has increased recently since it has effective and widespread usage areas. In this study, silver nanoparticles (AgNPs@Se) were synthesized using S. ebulus leaf extract and their structures were clarified by spectroscopic analyses including FTIR, UV–Vis, and XRD. The morphology and particle size of AgNPs@Se were determined by SEM analysis. Quantitative analysis of bioactive compounds of S. ebulus leaf extract was defined by HPLC analysis. Antioxidant activity of extract and AgNPs@Se was executed by DPPH•, ABTS•+, and FRAP assays. The antibacterial activity of AgNPs was carried out using agar well diffusion and microdilution broth methods. Quantitative analysis of bioactive compounds in S. ebulus leaf extract was established by HPLC. The average particle size of nanoparticles was calculated as 18.6 nm. Isoquercitrin was found as a major product. AgNPs@Se displayed excellent antioxidant activity, but they revealed a moderate antibacterial effect. The structure of nanoparticles was assigned as a face center cubic unit cell. Hence, nanoparticles could be a favorable agent for the pharmaceutical and food industry.

Aqueous Suspension of Porous SiO<sub>2</sub> Nanoparticles, Containing 9,10-diphenylanthracene, in Agrophotonics

An aqueous colloidal suspension of porous silicon dioxide nanoparticles containing an organic phosphor 9,10-diphenylanthracene was obtained by ultrasonic dispersion. The average size of suspension nanoparticles is 15–25 nm. This suspension has a characteristic absorption spectrum for diphenylanthracene in the region from 345 to 420 nm and a photoluminescence spectrum in the region from 400 to 550 nm. The resulting suspension was used for irrigation when growing bulbous plants (lilies and gladiolus) under conditions of a short light period with additional lighting with LEDs-based phytolamps with red and blue spectra. It has been established that the use of this suspension with nanoparticles that enter plants as an artificial photosynthetic pigment accelerates the growth of bulbous plants by an average of 15–20% compared to control samples under the same lighting conditions.

A novel green synthesis approach for shape memory polymer nanocomposites decorated with silver nanoparticles

AbstractA new, low‐cost, and direct green synthesis strategy was developed for the preparation of polymer composites composed of silver nanoparticles (AgNPs) decorated on a shape memory polymer blend using Rubus caesius L. leaves. X‐ray powder diffraction, ultraviolet‐visible spectroscopy (UV–vis), scanning electron microscopy, and energy dispersive X‐ray spectroscopy (EDS) elemental composition were applied to characterize the crystal size, morphology, and elemental composition of Ag‐NPs. UV–vis spectra detected the characteristic absorbance signal of AgNPs at about 430 nm, and the average crystal size of nanoparticles was calculated as about 12.60 nm. When nanocomposite films were characterized by attenuated total reflectance infrared spectroscopy, characteristic polylactic acid, and poly ethylene glycol (PEG) signals were determined. From the thermogravimetric analysis curves, it was determined that the amount of residue of nanocomposites increased as the amount of AgNP increased. It was seen that AgNPs did not affect the Tg temperature of the nanocomposite films, while it was also a proof that the polymer blend was immiscible. It was observed that the shape recovery properties of nanocomposite films were better with increasing AgNPs content. Finally, both green synthesized AgNPs and nanocomposites prepared with shape memory polymers showed very good antibacterial activity against Gram‐positive and Gram‐negative bacteria.Highlights Green synthesis of silver nanoparticles (AgNPs) was carried out with Rubus caesius L. leaves. The synthesized AgNPs were characterized by ultraviolet visible spectroscopy and x‐ray powder diffraction. Composite films were prepared with poly lactic acid/poly ɛ‐caprolactone blend by solvent casting method. The amount of residue of nanocomposites increased with increasing AgNPs percentage. The nanocomposite film containing 10% AgNPs has good activity.

Enhanced Release of Calcium Ions from Hydroxyapatite Nanoparticles with an Increase in Their Specific Surface Area.

Synthetic calcium phosphates, e.g., hydroxyapatite (HAP) and tricalcium phosphate (TCP), are the most commonly used bone-graft materials due to their high chemical similarity to the natural hydroxyapatite-the inorganic component of bones. Calcium in the form of a free ion or bound complexes plays a key role in many biological functions, including bone regeneration. This paper explores the possibility of increasing the Ca2+-ion release from HAP nanoparticles (NPs) by reducing their size. Hydroxyapatite nanoparticles were obtained through microwave hydrothermal synthesis. Particles with a specific surface area ranging from 51 m2/g to 240 m2/g and with sizes of 39, 29, 19, 11, 10, and 9 nm were used in the experiment. The structure of the nanomaterial was also studied by means of helium pycnometry, X-ray diffraction (XRD), and transmission-electron microscopy (TEM). The calcium-ion release into phosphate-buffered saline (PBS) was studied. The highest release of Ca2+ ions, i.e., 18 mg/L, was observed in HAP with a specific surface area 240 m2/g and an average nanoparticle size of 9 nm. A significant increase in Ca2+-ion release was also observed with specific surface areas of 183 m2/g and above, and with nanoparticle sizes of 11 nm and below. No substantial size dependence was observed for the larger particle sizes.

Investigation of the Thermodynamics for the Removal of As(III) and As(V) from Water Using Synthesized ZnO Nanoparticles and the Effects of pH, Temperature, and Time

In the present study, the removal of both As(III) and As(V) from aqueous solutions using synthesized ZnO nanomaterials was achieved. The ZnO nanomaterial was synthesized using a precipitation technique and characterized using XRD, SEM, and Raman spectroscopy. XRD confirmed the ZnO nanoparticles were present in the hexagonal wurtzite structure. SEM of the particles showed they were aggregates of triangular and spherical particles. The average nanoparticle size was determined to be 62.03 ± 4.06 nm using Scherrer’s analysis of the three largest diffraction peaks. Raman spectroscopy of the ZnO nanoparticles showed only ZnO peaks, whereas the after-reaction samples indicated that As(V) was present in both As(V)- and As(III)-reacted samples. The adsorption of the ions was determined to be pH-independent, and a binding pH of 4 was selected as the pH for reaction. Batch isotherm studies showed the highest binding capacities occurred at 4 °C with 5.83 mg/g and 14.68 mg/g for As(III) and As(V), respectively. Thermodynamic studies indicated an exothermic reaction occurred and the binding of both As(III) and As(VI) took place through chemisorption, which was determined by the ΔH values of −47.29 and −63.4 kJ/mol for As(V) and As(III), respectively. In addition, the change in Gibbs free energy, ΔG, for the reaction confirmed the exothermic nature of the reaction; the spontaneity of the reaction decreased with increasing temperature. Results from batch time dependency studies showed the reaction occurred within the first 60 min of contact time.

A novel N95 respirator with chitosan nanoparticles: mechanical, antiviral, microbiological and cytotoxicity evaluations

BackgroundIt is known that some sectors of hospitals have high bacteria and virus loads that can remain as aerosols in the air and represent a significant health threat for patients and mainly professionals that work in the place daily. Therefore, the need for a respirator able to improve the filtration barrier of N95 masks and even inactivating airborne virus and bacteria becomes apparent. Such a fact motivated the creation of a new N95 respirator which employs chitosan nanoparticles on its intermediate layer (SN95 + CNP).ResultsThe average chitosan nanoparticle size obtained was 165.20 ± 35.00 nm, with a polydispersity index of 0.36 ± 0.03 and a zeta potential of 47.50 ± 1.70 mV. Mechanical tests demonstrate that the SN95 + CNP respirator is more resistant and meets the safety requisites of aerosol penetration, resistance to breath and flammability, presenting higher potential to filtrate microbial and viral particles when compared to conventional SN95 respirators. Furthermore, biological in vitro tests on bacteria, fungi and mammalian cell lines (HaCat, Vero E6 and CCL-81) corroborate the hypothesis that our SN95 + CNP respirator presents strong antimicrobial activity and is safe for human use. There was a reduction of 96.83% of the alphacoronavirus virus and 99% of H1N1 virus and MHV-3 betacoronavirus after 120 min of contact compared to the conventional respirator (SN95), demonstrating that SN95 + CNP have a relevant potential as personal protection equipment.ConclusionsDue to chitosan nanotechnology, our novel N95 respirator presents improved mechanical, antimicrobial and antiviral characteristics.

A simple route to synthesize high-entropy carbide (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ nanoparticles with large covalent radius difference

Synthesis of high-entropy carbides containing lanthanide elements for improved high-temperature oxidation resistance is still a challenge due to the large covalent radius difference. Nanoparticles of a novel high-entropy carbide ceramic, (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ were successfully synthesized by a combination of organic sol-gel route and carbothermal reduction. The (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)Ox crystals with average size of ∼3 nm were synthesized at 220 °C in benzyl alcohol bath, dominated by the nucleation kinetics mechanism. Phase-pure (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ was achieved by using the (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)Ox crystals and glucose as the carbon source in Ar atmosphere at 1500 °C. Average crystal size of the (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ nanoparticles was ∼30 nm estimated by XRD spectra and TEM, exhibited rock-salt phase and high elemental homogeneity. The synthesis of (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ nanoparticles at low temperature was attributed to the fast nucleation that depending on high atomic homogeneity of the ultra-fine (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)Ox crystals.

Facile green synthesis of highly stable, water dispersible carbohydrate conjugated Ag, Au and Ag-Au biocompatible nanoparticles: Catalytic and antimicrobial activity

Highly stable carbohydrate conjugated silver, gold and bimetallic silver-gold alloy biocompatible and nearly monodisperse nanoparticles (NPs) have been synthesized through bio-reduction of aqueous solution of corresponding metal salt precursors mediated by aqueous extracts of a high altitude lichen, Lobaria retigera. The biomolecule accountable for the reduction, stabilization and capping of the metal nanoparticles is identified to be carbohydrates. The as-synthesized carbohydrate conjugated nanoparticles have excellent dispersibilty in water, phosphate, phosphate-buffered saline, and serum media. The resulting nanoparticles were completely stable for several months in water. The nanoparticles were characterized using UV–visible spectroscopy, TEM, EDX, FT-IR, powder XRD, DLS and CV study. Though mostly spherical in shapes, occasionally truncated triangular and rod shapes were also noted. The average particle sizes of Ag, Au and Ag-Au alloy nanoparticles as determined from TEM analysis are 14.5 nm, 11.7 nm and 16.3 nm, respectively. Cyclic voltammetry pointed to a relatively high electrode potential barrier for the synthesized nanomaterials. The prepared Ag, Au and Ag-Au alloy nanoparticles served as efficient catalysts for the degradation of hazardous pollutant dye, methyl orange (MO) with rate constat of 0.1496 min−1, 0.1049 min−1, and 0.1882 min−1. The bimetallic Ag-Au nanoparticles exhibited the most accelerated reduction with 90.6% degradation efficiency. The reduction kinetics for the reactions followed a pseudo-first order, kAu < kAg< kAu-Ag. The Ag and Ag-Au alloy NPs showed pronounced antimicrobial activity towards selected bacterial strains while AuNPs lacked any such activity.

Characterization and magnetic properties of CoFe2O4 nanoparticles synthesized by the co‐precipitation method

AbstractIn this study, the characterization and magnetic properties of CoFe2O4 nanoparticles synthesized by co‐precipitation method were investigated. The calcined products obtained were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X‐ray (EDAX), Fourier transformed infrared (FTIR) spectroscopy, and vibrating sample magnetometer. Crystallite size and phase composition were analyzed by X‐ray diffraction. Crystallite size and phase composition were analyzed by X‐ray diffraction. The average crystallite size of CoFe2O4 nanoparticles increased in the range of 15.85–32.14 nm with an increase in temperature from 500 to 700°C. It was observed that spherical CoFe2O4 nanoparticles were produced. Synthesis of CoFe2O4 nanoparticles was confirmed using XRD, SEM‐EDAX, and FTIR analyses. The effect of crystallite size, calcination temperature, and lattice parameter on saturation magnetization, remanent magnetization, coercivity, and magnetocrystalline anisotropy were investigated by vibrating sample magnetometer. As the crystallite size value increased, magnetocrystalline anisotropy also increased.