Research of the degree of compression and stability of liquid metal in a high&frequency magnetic field

The influence of a high-frequency magnetic field on liquid metal under melting conditions, the choice of technological parameters and the control of the melting process are considered. On the example of galinstan, the factors are established and the parameters are determined that cause the unstable movement of the metal. Keywords: high-frequency magnetic field, high-frequency inductors, galinstan, skin effect depth. [email protected], [email protected]

Thermal Traits of MNPs under High-Frequency Magnetic Fields: Disentangling the Effect of Size and Coating

We investigated the heating abilities of magnetic nanoparticles (MNPs) in a high-frequency magnetic field (MF) as a function of surface coating and size. The cobalt ferrite MNPs were obtained by a hydrothermal method in a water–oleic acid–ethanol system, yielding MNPs with mean diameter of about 5 nm, functionalized with the oleic acid. By applying another cycle of hydrothermal synthesis, we obtained MNPs with about one nm larger diameter. In the next step, the oleic acid was exchanged for 11-maleimidoundecanoic acid or 11-(furfurylureido)undecanoic acid. For the heating experiments, all samples were dispersed in the same solvent (dichloroethane) in the same concentration and the heating performance was studied in a broad interval of MF frequencies (346–782 kHz). The obtained results enabled us to disentangle the impact of the hydrodynamic, structural, and magnetic parameters on the overall heating capabilities. We also demonstrated that the specific power absorption does not show a monotonous trend within the series in the investigated interval of temperatures, pointing to temperature-dependent competition of the Brownian and Néel contributions in heat release.

Research of the tribotechnical properties of EN-GJV-400 cast iron modified by the TIG method in a high-frequency magnetic field

The tribological parameters of EN-GJV-400 cast iron and its modified surfaces obtained by melting, surface alloying with copper and nickel, as well as TIG welding in a high frequency magnetic field are studied. It is determined, that TIG welding in a high frequency magnetic field significantly increases the wear resistance of the material. Keywords cast iron, TIG welding, ledeburite, wear resistance. [email protected], [email protected]

Magnetic Graphene-Based Sheets for Bacteria Capture and Destruction Using a High-Frequency Magnetic Field

Magnetic reduced graphene oxide (MRGO) sheets were prepared by embedding Fe3O4 nanoparticles on polyvinylpyrrolidone (PVP) and poly(diallyldimethylammonium chloride) (PDDA)-modified graphene oxide (GO) sheets for bacteria capture and destruction under a high-frequency magnetic field (HFMF). The characteristics of MRGO sheets were evaluated systematically by transmission electron microscopy (TEM), scanning electron microscopy (SEM), zeta potential measurement, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), and X-ray photoelectron spectroscopy (XPS). TEM observation revealed that magnetic nanoparticles (8–10 nm) were dispersed on MRGO sheets. VSM measurements confirmed the superparamagnetic characteristics of the MRGO sheets. Under HFMF exposure, the temperature of MRGO sheets increased from 25 to 42 °C. Furthermore, we investigated the capability of MRGO sheets to capture and destroy bacteria (Staphylococcus aureus). The results show that MRGO sheets could capture bacteria and kill them through an HFMF, showing a great potential in magnetic separation and antibacterial application.