It has been shown that at spin-flop transition in spiral magnets LiCuVO 4 , LiCu 2 O 2 , and CuCrO 2 , Goldstone mode looses its stability.

In memory of Aleksandr Fedorovich Andreev, Dmitriev V.V., Kagan M.Yu., Kamenskii V.G., Kats E.I., Kveder V.V., Kreines N.M., Lebedev V.V., Marchenko V.I., Melnikovsky L.A., Smirnov A.I., Suslov I.M., Fomin I.A., Edel’man V.S.

It has been shown that at spin-flop transition in spiral magnets LiCuVO4, LiCu2O2, and CuCrO2, Goldstone mode looses its stability.

Evolution of the fundamental mode of acoustic oscillations in a cavity filled with gaseous helium has been studied during immersion of this resonator into a helium transport Dewar vessel. Critical behavior of the parameter of oscillation decay has been observed on approaching the level below which thermoacoustic instability arises.

We present the electron spin resonance study of the influence of an electric field on the low-field multiferroic magnetic state in LiCuVO4. The shift of the magnetic resonance spectra in the electric field has been observed experimentally. Symmetry analysis has been conducted in order to describe the static properties of the magnetic system. The low-frequency dynamics of LiCuVO4 in magnetic and electric fields was considered in the framework of hydrodynamic approach. It was shown that the application of the external electric field leads to the change of the configuration of the magnetic system before and after spin-flop reorientation. Satisfactory agreement was obtained between the results of experimental studies and theoretical consideration.

An explanation is proposed for the anomalous spin-flop in antiferromagnetic Cu(pz)2(ClO4)2. Due to the closeness of the monoclinic and tetrahedral lattices, the spin-flop in a small magnetic field can be accompanied by a transition from one to another antiferromagnetic vector. These two vectors transform into each other under the action of symmetry elements lost during monoclinic lattice distortions.

7Li NMR spectra were measured in a magnetic field up to 17 T at temperatures 5-30 K on single crystalline LiCu2O2. Earlier reported anomalies on magnetization curves correspond to magnetic field values where we observe changes of the NMR spectral shape. For the interpretation of the field and temperature evolutions of our NMR spectra, the magnetic structures were analyzed in the frame of the phenomenological theoretical approach of the Dzyaloshinskii-Landau theory. A set of possible planar and collinear structures was obtained. Most of these structures have an unusual configuration; they are characterized by a two-component order parameter and their magnetic moments vary harmonically not only in direction, but also in size. From the modeling of the observed spectra, a possible scenario of magnetic structure transformations is obtained.

Different methods have been proposed for the incorporation of a dye, vanadyl tetra-5,14,23,32-phenyl-2,3-naphthalocyanine, into the shells of polyelectrolyte capsules. Capsule preparation conditions have been selected to provide efficient incorporation of the dye and stability of capsules to aggregation. A suspension of the capsules has been irradiated with lasers operating at wavelengths belonging to the near-infrared spectral region. It has been found that the capsules can be disrupted under the irradiation. Continuous and pulsed laser radiations have been shown to have different effects on the capsules.

The influence of nanostructured CaCO3 particles, both uncoated and coated with a polyelectrolyte (poly(diallyldimethylammonium chloride), polyethyleneimine, fluorescein-5-isothiocyanate-labeled poly(allylamine hydrochloride), or sodium polystyrene sulfonate), on a stearic acid monolayer spread on the surface of an aqueous subphase has been studied. The interaction of the particles present in the subphase with the monolayer as depending on the presence and composition of a polymer coating has been estimated with the help of compression isotherms and the Brewster angle microscopy. The monolayers were transferred from the aqueous subphase onto a solid substrate and studied by scanning electron microscopy. Strong interaction has been revealed between the calcium carbonate particles and the stearic acid monolayer. It has been shown that the transfer of the monolayer from the aqueous suspension surface onto the solid substrate may be accompanied by the detachment of the polymer coating from the surface of CaCO3 particles or their transfer together with the monolayer.

X-ray studies of dipalmitoylphosphatidylcholine (DPPC) single layers on the surface of a liquid provide detailed information on the interaction of metal particles with a single layer upon an increase in the surface pressure up to the collapse. Two complementary X-ray methods are used: grazing incidence diffraction and the X-ray standing waves method. The experimental results obtained for a single layer formed on a colloidal solution of magnetite nanoparticles reveal that the increase in the surface pressure is accompanied by an increase in the concentration of nanoparticles near the surface. In a series of experiments where metal particles of submicron size are sputtered onto a DPPC single layer, a sharp decrease in the intensity of the fluorescence yield from metal atoms is observed while the single layer is compressed. These data suggest that metal particles deposited onto the surface of a single layer were extruded into the aqueous subphase.

The processes of structural rearrangement in a model membrane, i.e., an arachic acid monolayer formed on a colloidal solution of cerium dioxide or magnetite, are studied in situ in real time by the methods of X-ray standing waves and 2D diffraction. It is shown that the character of the interaction of nanoparticles with the monolayer is determined by their nature and sizes and depends on the conditions of nanoparticle synthesis. In particular, the structure formation in the monolayer–particle system is greatly affected by the stabilizer (citric acid), which is introduced into the colloidal solution during synthesis.

Polyelectrolyte capsules containing rhodamine 6G and fluorescein isothiocyanate in their shells are obtained by successive adsorption on spherical microscopic CaCO 3 particles followed by the dissolution of the latter. Suspensions of the capsules are irradiated with a laser operating at a wavelength corresponding to the absorption bands of the dyes, and it is shown that shell modification with the selected dyes promotes photosensitized disruption of these structures. The mechanism proposed for this disruption is realized via energy transfer from photoexcited dye molecules to the polymer matrix. Therewith, the dye-modified capsules are disrupted due to their nonuniform local heating.

There is an opinion in the medical associations that intranasal administration of medicine allows direct olfactory transfer of drugs into the central nervous system bypassing the blood–brain barrier. This approach could be a valuable solution to the problem of cerebral pathology treatment. We propose a new system of microcontainers for the delivery of an active component to the brain by intranasal administration. The microcontainers were fabricated on the base of porous calcium carbonate particles modified with mucoadhesive biocompatible polymer or polymer/surfactant coating. Loperamide was encapsulated in the proposed microcontainers as a model drug, which cannot pass the blood–brain barrier. The efficiency of microcontainers loaded with the anesthetic loperamide has been assessed by the formalin test in rats in vivo. The results of the in vivo experiments demonstrate decrease in the pain sensitivity after intranasal administration of proposed system, and benefit of mucoadhesive biocompatible coating aiming to improve the anesthetic effect.

It is shown that the model proposed by Canham quantitatively describes the observed biconcave shape of human erythrocytes.