This paper reports the synthesis of Fe3O4 nanoparticles with a hydrophobic surface functionalized with oleic acid through a simple and efficient route in air atmosphere and by co-precipitation. The hydrophobic surfactant agent was added in the magnetic crystal growth stage. Magnetic nanofluid was obtained by ultrasonic dispersion of magnetic nanoparticles in a carrier liquid � vegetable oil. The sample as powder has been characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), and Vibrating Sample Magnetometry (VSM) at room temperature. The magnetic nanofluid in vegetal oil was investigated by determining the stability of the nanoparticles in the vegetable oil through UV-Vis spectrometry method, the magnetic properties through Vibrating Sample Magnetometry (VSM) method at room temperature, and thermal conductivity as function of magnetic nanoparticles volume concentration and of temperature.

The use of nanotechnologies in the applied biomedical sciences can offer a new way to treat infections and disinfect surfaces, materials, and products contaminated with various types of viruses, bacteria, and fungi. The Cu-Au nanoparticles (NPs) were obtained by an eco-friendly method that allowed the obtaining in a one-step process of size controlled, well dispersed, fully reduced, highly stable NPs at very mild conditions, using high energy ionizing radiations. The gamma irradiation was performed in an aqueous system of Cu2+/Au3+/Sodium Dodecyl Sulfate (SDS)/Ethylene Glycol. After irradiation, the change of color to ruby-red was the first indicator for the formation of NPs. Moreover, the UV-Vis spectra showed a maximum absorption peak between 524 and 540 nm, depending on the copper amount. The Cu-Au NPs presented nearly spherical shapes, sizes between 20 and 90 nm, and a zeta potential of about −44 mV indicating a good electrostatic stability. The biocidal properties performed according to various standards applied in the medical area, in dirty conditions, showed a 5 lg reduction for Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus hirae, a 5 lg reduction for both enveloped and non-enveloped viruses such as Adenovirus type 5, Murine Norovirus, and human Coronavirus 229E, and a 4 lg reduction for Candida albicans, respectively. Thus, the radiochemically synthesized Cu-Au alloy NPs proved to have high biocide efficiency against the tested bacteria, fungi, and viruses (both encapsulated and non-encapsulated). Therefore, these nanoparticle solutions are suitable to be used as disinfectants in the decontamination of hospital surfaces or public areas characterized by high levels of microbiological contamination.

The hydrophilic g-Fe2O3 nanoparticles coated with polyvinylpyrrolidone (PVP) were prepared in one step of the modified polyol method combined with an additional heat treating. The presence of maghemite (g-Fe2O3) phase was confirmed by using X-ray diffraction (XRD) and Raman Spectrometry on powder. FT-IR spectroscopy confirmed the presence of PVP on the nanoparticles surface and the Zeta potential also supported the coating of nanoparticles with a layer of PVP and a good stability in aqueous medium. SEM analysis showed that the prepared g-Fe2O3 nanoparticles have a spherical structural morphology with the tendency of agglomeration. Hysteresis loop shows a ferromagnetic behaviour at room temperature with a saturation magnetization up to 57 emu/g.

This paper reports the synthesis of FeNi3 alloy nanoparticles by chemical reduction of the Fe2+ and Ni2+ ions, from the corresponding chlorides, with hydrazine (N2H4�H2O) as a reducing agent in aqueous solution at room temperature by modifying the molar ratio of the ions Fe2+: Ni2+, reaction time, with and without amine-type growth promoter, and reducing both, with or without ultrasonic aid. The FeNi3 alloy nanoparticles have been investigated by XRD, EDS spectrum analysis, SEM and VSM. When the molar ratio of Fe2+ and Ni2+ is equal to 1:3, reducing both, with or without ultrasonic aid, Fe2+ and Ni2+ were completely reduced into Fe and Ni, resulting FeNi3 alloy with a face-centered cubic (fcc) crystal structure. EDS analysis supported the presence of metal ions in atomic weight corresponding to the stoichiometric ratio of initial reaction. SEM analysis showed that nanoparticles of FeNi3 alloy have a spherical structural morphology. Hysteresis loop show a ferromagnetic behaviour of the FeNi3 alloy nanoparticles at room temperature.

Among novel magnetic intermetallics based on rare earth-transition compounds, the Nd2Fe14B/α-Fe isotropic nanocomposites have been obtained by recrystallization from an amorphous phase, prepared by melt spinning. For variable 5 wt.% Fe and 10 wt.% Fe contents we recorded transmission 57Fe Mössbauer spectra at the room temperature, hardened of the α-Fe phase by exchange interactions. The spectra have been analyzed in terms of ten Zeeman sextets and one paramagnetic doublet related to the Nd1.1Fe4B4 phase. One sextet corresponds to the α-Fe phase, whereas others are attributed to six non-equivalent Fe sites in the Nd2Fe14B structure, namely 16k1, 16k2, 8j1, 8j2, 4c, and 4e. The three remaining sextets belong to the Fe3B structure with three inequivalent Fe sites FeI(8g), FeII(8g) and FeIII(8g). All relevant parameters for both nanocomposites: the magnetic hyperfine field, the isomer shift and the quadrupole splitting are determined for each of these sites.

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By an appropriate processing of the pyritic ashes (resulted as residue in the fabrication process of the sulphuric acid) can be valorised the metallic elements. The paper presents the magnetic characteristics of the powders before and after the thermal annealing, and also the flowability and the granulometric characteristics of these powders. Starting from a very low magnetization, σ = 3.65 emu/g, the Fe amount of the powders is dramatically increased, after an appropriate thermal treatment, to approx. 34 %, corresponding to σ=128 emu/g. The Fe-enriched powders, embedded in epoxy resin matrix, generate a composites material, which can be used as electromagnetic shields, based on their materials properties (permittivity, permeability and electrical conductivity) in the 1000 – 2500 MHz range.

In this study, L-lysine coated �a-Fe2O3 nanoparticles were synthesized by a chemical approach in two steps. In the first step �a-Fe2O3 nanoparticles were synthesized by a polyol-reduction method. XRD analysis confirmed the presence of cubic maghemite phase with an average crystallite size of 9.2 nm. SEM analysis showed that the prepared �a-Fe2O3 nanoparticles have a spherical structural morphology with the tendency of agglomeration and with size in the range 8.36- 10.69 nm. The �a-Fe2O3 nanoparticles were coated with L-lysine in the second stage in an aqueous dispersion with ultrasonication followed by a gentle heating at 40��C. FT-IR spectroscopy confirmed the presence of L-lysine on the nanoparticles surface and the Zeta potential also supported the coating of nanoparticles with a hydrophilic layer of amino acid (L-lysine) and a good stability in aqueous medium. Hysteresis loop shows a ferromagnetic behavior at room temperature for both samples.