The paper focuses on the issues of improving the interference immunity of space communication systems with quadrature amplitude modulation. As one of the possible approaches, the application of ...methods of blind separation of signals and interference in the receive paths of space communication channels is considered. Using the method of independent component analysis as an example, the interference immunity of communication channel with quadrature amplitude modulation is assessed during the operation in a complex interference environment including pulse noise-like interference. The bit error rate is considered as the main indicator characterizing the interference immunity of a radio system. The method of simulation modeling was used for the research. Within the independent component analysis method, the efficiencies of its implementation algorithms, such as SOBI, AMUSE, and CubICA, are compared.
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Y
3
Fe
5 –
x
Al
x
O
12
(
х
= 0, 0.5, 1.0, 1.5, 2.0) materials prepared by sol–gel synthesis have been characterized by scanning electron microscopy, X-ray diffraction, Raman and Mössbauer ...spectroscopies, field- and temperature-dependent saturation magnetization measurements, and magnetocaloric measurements in an ac magnetic field. We have examined the effect of aluminum concentration on the magnetic and crystal structures and magnetothermal properties of the garnet ferrite particles.
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Iron-containing oxides form one of the most important classes of functional materials, which find a wide variety of applications. A promising approach is their use in biomedical technologies as ...components of systems for visualization, drug delivery, magnetic hyperthermia, etc. Nanocrystalline particles of Y
3
Fe
5
O
12
garnet, obtained by glycine-nitrate combustion with subsequent thermal treatment, have been experimentally investigated. The results of studying the evolution of the crystal and magnetic structure of Y
3
Fe
5
O
12
nanoparticles in dependence of the synthesis temperature are presented. A complex analysis using X-ray diffractometry, scanning electron microscopy, and Mössbauer spectroscopy has been performed. A relationship of the size and structural quality of Y
3
Fe
5
O
12
nanoparticles with the observed magnetic characteristics is revealed.
Scanning electron microscopy, X-ray diffraction, Raman and Mössbauer spectroscopies, field and temperature dependences of magnetic saturation and magnetocaloric effect in alternating magnetic fields ...are used to study submicron yttrium ferrite particles prepared by reverse coprecipitation from nitrate solutions at various pH values and subsequent heat treatment. The size, phase purity, and structural state of prepared particles determine the magnitude of the magnetocaloric effect exhibited by the particles in the external alternating magnetic field (370 kHz, 1.77 kA/m).
Nanocomposites based on nanoparticles of iron oxides formed inside porous matrices were studied. Mesostructured silica material SBA-15 impregnated with an aqueous solution of iron(III) oxalate was ...heattreated in oxidizing (air) and reducing (Ar + 5% H
2
) media. The resulting samples exhibited small oxide particle sizes (ca. 5 nm) and sufficiently uniform distribution of iron whose content was ~16 wt %.
The existence of hydrate forms of iron(III) oxalate, which noticeably differ from each other in the Mössbauer spectral parameters (isomer shift and quadrupole splitting), is detected. In the ...assumption of the formation of phases with different structural characteristics, the samples of compound under study are examined by the powder X-ray diffraction analysis (including the application of synchrotron radiation), Mössbauer and IR spectroscopy. It is shown that the phase characterized by new values of the Mössbauer parameters has its own IR spectrum and it is X-ray amorphous and metastable.
Herein, using the systematic experimental characterization and density functional theory calculations, the effects of Ni elemental substitution on the crystal structure, cation distribution, magnetic ...properties, and heat generation ability of Mg1–xNixFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) have been reported. We demonstrate that the presence of Ni can lead the lattice shrinkage, phase transition from partially to fully inverse spinel structure, and multi-domain structures in the samples. Moreover, Ni substitutional atoms make magnetically harder ferrite, associated with increasing magnetic inhomogeneity. Remarkably, anomalous enhancements of magnetic anisotropic and coercivity have been observed in Mg0.4Ni0.6Fe2O4. Heat generation ability (SAR) increases from 242 W g−1 for x = 0–391 W g−1 for x = 0.6 at an AC magnetic field of 370 kHz frequency. Thus, the magnetic hyperthermia of Mg0.4Ni0.6Fe2O4 sample on HeLa shows promising results that the viability of cells decreases to 25 % after 5 sessions. The present experimental and theoretical systematic studies provide novel avenue and paradigm for the development of ferrite nanoparticles with high heat generation ability and magnetic properties for biomedical applications.
•The effects of Ni substitution on MgFe2O4 have been studied by experimentally and theoretically.•Ni leads the lattice shrinkage, phase transition to fully inverse, multi-domain structures and magnetically harder ferrite.•The enhancement of the magnetic property originates from the anisotropic property resulting from the structural changes.•Mg0.4Ni0.6Fe2O4 composite displays the most pronounced magnetic and heat generation properties.•The magnetic hyperthermia of Mg0.4Ni0.6Fe2O4 composite on HeLa shows promising results.
The influence of mesoporous silica matrix on the thermolysis of ferric oxalate loaded into its pores was studied. A significant decrease in the onset of the thermal decomposition temperature of ...ferric oxalate was observed. The maximum of the second decomposition stage of ferric oxalate in argon atmosphere was also appeared to be shifted by 30-40°C when thermolysis occurred in pores. These effects were accounted for the amorphous state of ferric oxalate and enhanced reactivity of highly dispersed particles
The present work is dedicated to the research of nanocomposites based on particles of different iron oxides developed inside mesoporous SBA-15 silica soaked in iron(III) oxalate aqueous solution by ...thermal treatment under various conditions (temperature, environment). The effect of the conditions applied on properties and phase composition of the samples has been studied. All the samples obtained are superparamagnetic with roughly uniform iron distribution.
