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Nickel manganese oxide (NiMnO3) combines magnetic and dielectric properties, making it a promising material for sensor and supercapacitor applications, as well as for catalytic water splitting. The efficiency of its utilization is notably influenced by particle size. In this study, we investigate the influence of thermal treatment parameters on the phase composition of products from alkali co-precipitation of nickel and manganese (II) ions and identify optimal conditions for synthesizing phase-pure nickel manganese oxide. Ultrafine nanoparticles of NiMnO3 (with sizes as small as 2 nm) are obtained via liquid-phase ultrasonic dispersion, exhibiting a narrow size distribution. A systematic exploration of the solvent nature (water, N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide) on the efficiency of ultrasonic dispersion of NiMnO3 nanoparticles is provided. It is demonstrated that particle size is influenced not only by absorbed acoustic power, dependent on the physical properties of the used solvent (boiling temperature, gas solubility, viscosity, density) but also by the chemical stability of the solvent under prolonged ultrasonic treatment. Our findings provide insights for designing ultrasonic treatment protocols for nanoparticle dispersions with tailored particle sizes.

One of the promising novel methods for radical tumor resection at a single-cell level is magneto-mechanical microsurgery (MMM) with magnetic nano- or microdisks modified with cancer-recognizing molecules. A low-frequency alternating magnetic field (AMF) remotely drives and controls the procedure. Here, we present characterization and application of magnetic nanodisks (MNDs) as a surgical instrument (“smart nanoscalpel”) at a single-cell level. MNDs with a quasi-dipole three-layer structure (Au/Ni/Au) and DNA aptamer AS42 (AS42-MNDs) on the surface converted magnetic moment into mechanical and destroyed tumor cells. The effectiveness of MMM was analyzed on Ehrlich ascites carcinoma (EAC) cells in vitro and in vivo using sine and square-shaped AMF with frequencies from 1 to 50 Hz with 0.1 to 1 duty-cycle parameters. MMM with the “Nanoscalpel” in a sine-shaped 20 Hz AMF, a rectangular-shaped 10 Hz AMF, and a 0.5 duty cycle was the most effective. A sine-shaped field caused apoptosis, whereas a rectangular-shaped field caused necrosis. Four sessions of MMM with AS42-MNDs significantly reduced the number of cells in the tumor. In contrast, ascites tumors continued to grow in groups of mice and mice treated with MNDs with nonspecific oligonucleotide NO-MND. Thus, applying a “smart nanoscalpel” is practical for the microsurgery of malignant neoplasms.

The paper presents the results of tensile and impact bending tests of 17%Cr-19%Mn-0.53%N high-nitrogen austenitic stainless steel in temperatures ranging from −196 to 20 °C. The steel microstructure and fracture surfaces were investigated using transmission and scanning electron microscopes, as well as X-ray diffraction analysis. The steel experiences a ductile-to-brittle transition (DBT); however, it possessed high tensile and impact strength characteristics, as well as the ductile fracture behavior at temperatures down to −114 °C. The correspondence between γ–ε microstructure and fracture surface morphologies was revealed after the tensile test at the temperature of −196 °C. In this case, the transgranular brittle and layered fracture surface was induced by ε-martensite formation. Under the impact bending test at −196 °C, the brittle intergranular fracture occurred at the elastic deflection stage without significant plastic strains, which preceded a failure due to the high internal stresses localized at the boundaries of the austenite grains. The stresses were induced by: (i) segregation of nitrogen atoms at the grain boundaries and in the near-boundary regions, (ii) quenching stresses, and (iii) reducing fcc lattice volume with the test temperature decrease and incorporation of nitrogen atoms into fcc austenite lattice. Anisotropy of residual stresses was revealed. This was manifested in the localization of elastic deformations of the fcc lattice and, consequently, the stress localization in -oriented grains; this is suggested to be the reason of brittle cleavage fracture.

Mn5Ge3 epitaxial thin films previously grown mainly on Ge substrate have been synthesized on Si(111) using the co-deposition of Mn and Ge at a temperature of 390 °C. RMS roughness decreases by almost a factor of two in the transition from a completely polycrystalline to a highly ordered growth mode. This mode has been stabilized by changing the ratio of the Mn and Ge evaporation rate from the stoichiometric in the buffer layer. Highly ordered Mn5Ge3 film has two azimuthal crystallite orientations, namely Mn5Ge3 (001) [1-10] and Mn5Ge3 (001) [010] matching Si(111)[-110]. Lattice parameters derived a (7.112(1) Å) and c (5.027(1) Å) are close to the bulk values. Considering all structural data, we proposed a double buffer layer model suggesting that all layers have identical crystal structure with P6₃/mcm symmetry similar to Mn5Ge3, but orientation and level of Si concentration are different, which eliminates 8% lattice mismatch between Si and Mn5Ge3 film. Mn5Ge3 film on Si(111) demonstrates no difference in magnetic properties compared to other reported films. TC is about 300 K, which implies no significant excess of Mn or Si doping. It means that the buffer layer not only serves as a platform for the growth of the relaxed Mn5Ge3 film, but is also a good diffusion barrier.

Magnetization reversal processes in the NiFe/FeMn exchange biased structures with various antiferromagnetic layer thicknesses (0–50 nm) and glass substrate temperatures (17–600 °C) during deposition were investigated in detail. Magnetic measurements were performed in the temperature range from 80 K up to 300 K. Hysteresis loop asymmetry was found at temperatures lower than 150 K for the samples with an antiferromagnetic layer thickness of more than 10 nm. The average grain size of FeMn was found to increase with the AFM layer increase, and to decrease with the substrate temperature increase. Hysteresis loop asymmetry was explained in terms of the exchange spring model in the antiferromagnetic layer.

During the past few decades, hybrid nanoparticles (HNPs) based on a magnetic material and gold have attracted interest for applications in catalysis, diagnostics and nanomedicine. In this paper, magnetic CoFe2O4/Au HNPs with an average particle size of 20 nm, decorated with 2 nm gold clusters, were prepared using methionine as a reducer and an anchor between CoFe2O4 and gold. The methionine was used to grow the Au clusters to a solid gold shell (up to 10 gold deposition cycles). The obtained nanoparticles (NPs) were studied by X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-Ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy techniques. The TEM images of the obtained HNPs showed that the surface of cobalt ferrite was covered with gold nanoclusters, the size of which slightly increased with an increase in the number of gold deposition cycles (from 2.12 ± 0.15 nm after 1 cycle to 2.46 ± 0.13 nm after 10 cycles). The density of the Au clusters on the cobalt ferrite surface insignificantly decreased during repeated stages of gold deposition: 21.4 ± 2.7 Au NPs/CoFe2O4 NP after 1 cycle, 19.0 ± 1.2 after 6 cycles and 18.0 ± 1.4 after 10 cycles. The magnetic measurements showed that the obtained HNPs possessed typical ferrimagnetic behavior, which corresponds to that of CoFe2O4 nanoparticles. The toxicity evaluation of the synthesized HNPs on Chlorella vulgaris indicated that they can be applied to biomedical applications such as magnetic hyperthermia, photothermal therapy, drug delivery, bioimaging and biosensing.