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A comprehensive study is made of the properties of samples of BiFe1−xMnxO3 (0.05 ≤ x ≤ 0.15) solid solutions synthesized using the sol-gel technique. Stabilization of the main phase, a reduction in the average granule size, and an increase in the dielectric constant are observed upon an increase in concentration x. The presence of Mn ions in BiFe1−xMnxO3 solid solutions results in semiconductor-type conductivity and the emergence of magnetic ordering at 605 K (х = 0.05) and 550 K (х = 0.15).

A slowly decaying anomaly of magnetic susceptibility (characteristic time τ ~ 103 s) is revealed in studying the ferromagnetic–paramagnetic phase transition in polycrystalline cobaltite GdBaCo2O5.53 that occurs due to the remaining short-range magnetic order at temperatures above the Curie point (TC = 275 K). High hydrostatic pressures (up to 1.48 GPa) are found to have a weak effect on TC with baric coefficient dTC/dP = 2.1 K/GPa.

Complex magnetic, resistive, and dielectric studies of Pr1–xCaxMnO3 (х = 0.15–0.30) manganites reveal multiferroic properties at T≫TC in these solid solutions. States with local magnetization in the form of ferromagnetic clusters (nucleation temperature T* ≈ 700 K) and high dielectric constants coexist in the temperature window TC ≤ T ≤ T*. There is a correlation between the temperature dependences of specific resistance and specific magnetization.

We studied the adjuvant properties of micelles from nonionogenic detergents, liposome, and selenium nanoparticles containing extracellular and intracellular vaccine antigens of a weakly virulent α-hemolytic Escherichia coli B-5 strain used for the immunization of experimental animals. Triton X-100 was used as a nonionogenic detergent for micelle preparation. The liposomes were obtained on the basis of lecithin from a chicken egg and E. coli B-5 membrane lipids. Native lipoproteins of E. coli B-5 cells and peptides for the proteolytic hydrolysis of toxin-containing culture liquid were used as antigens for micelles and liposomes. The obtained data suggested that micelles, liposomes, and selenium nanoparticles can be used for immunization with cellular and extracellular E. coli antigens.

Structural, magnetic, and resonance studies of BixLa1–xMnO3 are performed. Nanopowders of weakly doped compounds (x = 0.0–0.1) with particle sizes of ≤40 nm are prepared using the sol–gel technique. Nanopowder sintering under the same conditions leads to a sharp increase in the mean granule size with increasing Bi concentration. The 55Mn NMR signal of manganites prepared via solid synthesis corresponds to rapid exchange Mn4+ ↔ Mn3+. Measurements of the magnetic susceptibility reveal an inhomogeneity in the ferromagnetic state of the BixLa1–xMnO3 system.

Measurements of the capacitance and tangent of dielectric loss angle, impedance and resistance, magnetization in a magnetic field of 8.6 kOe BiMnxFe1-xO3 films in the temperature range 80-600 K were carried out. The anomalies of the dielectric properties are explained in the Debye model and correlate with changes in the magnetic moment versus temperature.

We report the synthesis of polycrystalline La x MnO3 + δ (x = 0.815, 0.90, 0.94, 0.97, 1.0) samples and their crystal structure at 300 K. All of the samples are single-phase and have an orthorhombically distorted (Pnma) perovskite structure. Also possible is that some of the samples have a rhombohedrally distorted \(\left( {R\bar 3c} \right)\) structure. The unit-cell parameters of La0.90MnO3 differ most significantly from those of the x = 1.0 material. We have assessed the structural imperfection of the samples (cation vacancy concentration) and proposed overall chemical formulas of the manganites that take into account structural defects. Comparison of the X-ray and measured (hydrostatic weighing) densities of the samples demonstrates that their relative density increases with decreasing lanthanum content.

Magnetic and resonance studies of the system of polycrystalline samples of self-doped manganites LaxMnO3 + δ (x = 0.815, 0.90, 0.94, 0.97, and 1.0) have been performed in a temperature range of 77–300 K. According to 55Mn NMR data, all samples contain a ferromagnetic phase at 77 K. As the defect density increases (x changes from 1.0 to 0.815), samples become more magnetically ordered. In this case, the ferromagnetic state of the system gradually changes from a mixed state in which both ferromagnetic insulating (basic) and ferromagnetic metal (for x = 0.97 and 1.0) phases coexist to only the ferromagnetic metal state (for x = 0.815 and 0.90). It has been shown that both ferromagnetic metal and ferromagnetic insulating phases are inhomogeneous, and either phase consists of two phases with different dynamics of nuclear spins and different Curie temperatures. The diagram of the magnetic phase state of the LaxMnO3 + δ system (x = 0.815, 0.90, 0.94, 0.97, 1.0) has been constructed for a temperature range of 120–240 K and Mn4+ contents of 12–30%.

The conditions are found under which quadratic magneto-optic interaction causes the formation of virtual surface magnetic TM and TE polaritons propagating along the interface between an antiferromagnet (AFM) and an ideal metal or between an AFM and an insulator in an external static electric field directed along the easy axis of the AFM. The specific features of the reflection of a bulk electromagnetic wave incident from vacuum onto the AFM surface are studied under these conditions.

By using an easy-axis antiferromagnetic material as an example, the conditions are found under the fulfillment of which, the quadratic magneto-optical interaction in an external dc electric field perpendicular to the easy axis gives rise to the formation of a new type of virtual surface magnetic TM polaritons at the interface both between an antiferromagnet and an ideal metal and between an antiferromagnet and vacuum.

The anomalies arising in the reflection of a bulk TM wave from the surface of a slab of a nongyrotropic multiferroic on account of anisotropy of the magnetoelectric interaction are investigated for the example of a ferroelectric antiferromagnet in the collinear phase under the condition that the ferroelectric axis is perpendicular to the interface between the media.

The paper presents results obtained in studying 139La and 55Mn nuclear magnetic resonance spectra and nuclear magnetic relaxation in the temperature range 21–220 K augmented by data on the magnetic and transport properties of ferromagnetic (La1−x Srx)1−δMnO3 manganites (x=0, 0.075, and 0.125, δ≈0.0−0.05). The transition from the ferromagnetic state with semiconductor-type conductivity to the ferromagnetic state with metallic conductivity as the degree of doping x increased was related to the redistribution of the volumes of two phases (two types of regions) with different degrees of freedom of electron holes on manganese sites. The ferromagnet-paramagnet phase transition was a smooth redistribution of the volumes of ferromagnetic and paramagnetic (or antiferromagnetic) regions in a wide temperature range. Ferromagnetic conductivity was caused by the “double exchange” mechanism, whereas, in comparatively nonconducting regions, double exchange was considerably weakened and involved fairly slow thermally activated motion of Jahn-Teller polarons. The dynamics of nuclear spins was evidence of internal inhomogeneity of each of these phases.

It is illustrated by specific example that, near a dipole-active intrinsic ferroelastic phase transition characterized by a single-component order parameter, a surface electroacoustic shear wave can arise, if spatial dispersion is included, even in the case of the surface of a piezoelectric crystal being rigidly fixed.

The NMR on 57Fe nuclei located at octahedral and tetrahedral sites of Y3-xErxFe5O12 garnets was measured at liquid-helium temperature. By analysing the results on polycrystalline samples with x=0.2 and 2.8, obtained in a zero external field (magnetization along the (100) direction), the authors determined the non-collinear umbrella-like arrangement of the magnetic moments of Er3+ ions and modification of the hyperfine field on 57Fe nuclei caused by Er to or from Y substitution. The umbrella angle is 23(+or-3) degrees . These results were then used in the analysis of NMR of the single crystal with x=0.12 in an external magnetic field parallel to the (111) direction. In this case there are two angles characterizing the magnetic umbrella, their values being 12(+or-10) degrees and 48(+or-9) degrees .

NMR of 57Fe was studied by the two pulse spin echo method in systems Er(x)Y(3−x)Fe5012. For small (x 2.7) concentrations of Er the spectra of 57Fe exhibit resolved satellite lines. The splitting between the satellite and the parent line reflects the change of the dipolar field on the Fe nuclei (diamagnetic yttrium is replaced by magnetic erbium ion) and the change which the substitution causes in the electronic structure of the ferric ion. Relative importance of these effects is discussed.

The expression of heat‐shock proteins (HSPs) is enhanced in stressed cells and can protect cells from stress‐induced injury. However, existing data about the relationship between apoptosis and HSP expression is contradictory. In this paper, a mouse lymphoma cell death model system is used to detect simultaneously both the process of apoptosis and the level of HSP expression. The model was established after discovering that spontaneous apoptosis and spontaneous cell surface HSP expression occurs in EL‐4 mouse lymphoma cells during normal optimal culture conditions. The data show that apoptotic EL‐4 cells had higher levels of hsp25, hsp60, hsp70 and hsp90 exposed on the plasma membrane surface than viable cells. The level of surface HSPs was found to increase through several stages of early and late apoptotic death as measured by flow cytometry, with the highest levels observed during the loss of cell membrane phospholipid asymmetry. Heat shock and actinomycin D significantly increased the proportion of apoptotic cells in culture. However, hyperthermia only stimulated a weak and temporary increase in surface HSP expression, whereas actinomycin D strongly elevated the level of surface and intracellular HSPs, particularly in live cells. These results show an associative relationship between apoptosis and HSP expression. The relationship between the progression of cell death and HSP expression suggests a role for membrane HSP expression in programmed cell death.

The nuclear quadrupole resonance (NQR) on Ba nuclei was studied in four samples of ${\mathrm{BaBiO}}_{3}$ prepared in different ways and, in addition, in ${\mathrm{BaPbO}}_{3}.$ The spectrum of ${}^{137}\mathrm{Ba}$ at $T=4.2 \mathrm{K}$ consists of a relatively broad line centered near 18 MHz for all ${\mathrm{BaBiO}}_{3}$ samples and near 13 MHz for ${\mathrm{BaPbO}}_{3}.$ The integrated intensity of the ${}^{137}\mathrm{Ba}$ resonance in the ceramic sample of ${\mathrm{BaBiO}}_{3}$ synthesized at $800\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ is approximately twice as large as that in ceramic samples and a single crystal prepared at $930--1080\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}.$ The decrease of the NQR signal can be attributed to the partial disordering of charge-disproportionated Bi ions on the two inequivalent sites. The broadening of the resonance indicates that local distortions of the crystal structure exist in both compounds. The point-charge model was used to analyze the electric-field gradient on the Ba sites.

The magnetic, resonance, and electric properties of LaxMnO3+δ (0.815≤x≤1.0) polycrystalline samples have been studied in the temperature range of 77–370 K and at high pressures of up to 11.5 kbar. It is shown that the increase in the La/Mn ratio gives rise to a change in the low temperature magnetic state from ferromagnetic to cluster spin glass, as well as to a drastic transformation of electric properties. A peculiar double-peaked shape is characteristic of the resistivity versus temperature curves for the intermediate range of x values. Within this range, the application of high pressures drastically changes both the value of resistivity and the character of its temperature dependence. It is shown that the approach, which regards the state of LaxMnO3+δ polycrystals as a mixture of interpenetrating paramagnetic insulating and ferromagnetic metallic phases, is able to successfully describe the peculiarities of the temperature dependence of total resistivity, as well as the features of its transformation ...

The effects of hydrostatic pressure up to 1.3 GPa on the Neel temperature in orthorhombic antiferromagnetic La 2 CuO 4+δ have been investigated using the 139 La NQR method. A positive sign of the pressure derivative, d T N /d P = 7.1 K/GPa, as well as an increase in the critical index β from 0.29 at ambient pressure to 0.33 at 1.3 GPa have been observed. The results were processed using the Green function method.