Comparison of early reactions of the blood system in rats to immobilization, the action of hypoxia and the administration of erythopoietin

Three series of experiments were simultaneously carried on rats with the purpose of studying the action of different stimulants on the blood system; rats were subjected to immobilization, hypoxic hypoxia and erythropoietin administration. Changes in various cellular forms in the bone marrow, the thymus and the spleen were studied. A unitypical reaction, as in stress, was noted during the first hours; a reduction of the cell count in the lymphoid organs, a reduction of granulocytes and an increase of lymphoid cells in the bone marrow. The differences were chiefly quantitative. This was followed by stimulation of myelo and erythropoiesis determined by the specific features of the action applied. Nonspecific blood reaction was apparently due to activation of the adaptation mechanisms

Investigation of phase transitions in multiferroics HоFe3-xGax(BO3)4 and TbFe3-xGax(BO3)4 solid solution with huntite structure

RFBR funded the reported study according to the research project № 18-02-00754

High-resolution spectroscopy, crystal-field calculations, and quadrupole helix chirality of DyFe<inf>3</inf>(BO<inf>3</inf>)<inf>4</inf>

© The Authors, published by EDP Sciences. High-resolution polarized transmission spectra of Dy Fe 3 (BO 3 ) 4 single crystals were investigated in broad spectral (10-23000 cm -1 ) and temperature (3.5-300 K) ranges. Energies of the dysprosium levels in the paramagnetic and antiferromagnetic phases were determined. On the basis of these data and preliminary calculations in the frameworks of the exchange-charge model, we determined the crystal-field and Dy-Fe exchange interaction parameters of the Dy 3+ ions at sites with the point C2 symmetry corresponding to the enantiomorphic P3121 and P3221 space groups. The values of electronic quadrupole moments of the Dy 3+ ions were calculated, which enabled us to interpret results of the work [Usui et al., Nature Mater. 13, 611 (2014)] on the observation of domains of different quadrupole chirality in DyFe3(BO3)4

Magnetic Phase Transitions in the NdFe_3(BO_3)_4 multiferroic

Low temperature studies of the behavior of the sound velocity and attenuation of acoustic modes have been performed on a single crystal NdFe_3(BO_3)_4. Transitions of the magnetic subsystem to the antiferromagnetically ordered state at T_N \approx 30.6 K have been revealed in the temperature behavior of the elastic characteristics. The features in the temperature behavior of elastic characteristics of the neodymium ferroborate and its behavior in the external magnetic field, applied in the basic plane of the crystal, permit us to suppose that the transition to an incommensurate spiral phase is realized in the system. This phase transition behaves as the first order one. H-T phase diagrams for the cases H \parallel a and H \parallel b have been constructed. The phenomenological theory, which explains observed features, has been developed

Spectroscopy of f-f transitions, crystal-field calculations, and magnetic and quadrupole helix chirality in DyF e3(B O3)4

© 2017 American Physical Society.We present the results of temperature- and polarization-dependent high-resolution optical spectroscopy studies of DyFe3(BO3)4 performed in spectral ranges 40-300cm-1 and 3000-23000cm-1. The crystal-field (CF) parameters for the Dy3+ ions in the P3121 (P3221) phase of DyFe3(BO3)4 are obtained from calculations based on the analysis of the measured f-f transitions. Recently, quadrupole helix chirality and its domain structure was observed in resonant x-ray diffraction experiments on DyFe3(BO3)4 using circularly polarized x rays [T. Usui, Y. Tanaka, H. Nakajima, M. Taguchi, A. Chainani, M. Oura, S. Shin, N. Katayama, H. Sawa, Y. Wakabayashi, and T. Kimura, Nat. Mater. 13, 611 (2014)10.1038/nmat3942]. Using the obtained set of the CF parameters, we calculate temperature dependencies of the electronic quadrupole moments of the Dy3+ ions induced by the low-symmetry (C2) CF component and show that the quadrupole helix chirality can be explained quantitatively. We also consider the temperature dependencies of the bulk magnetic dc-susceptibility and the helix chirality of the single-site magnetic susceptibility tensors of the Dy3+ ions in the paramagnetic P3121 (P3221) phase and suggest the neutron and resonant x-ray diffraction experiments in a magnetic field to reveal the helix chirality of field-induced magnetic moments

Crystal field and exchange interactions in the SmFe3(BO 3)4 multiferroic

The optical spectra of oriented SmFe3(BO3) 4 single crystals are studied in the region of the f-f transitions in the Sm3+ ion by Fourier spectroscopy. The energies, the symmetry properties, and the exchange splittings of the Stark sublevels of the ground and 17 excited multiplets of the Sm3+ ion in a crystal field of symmetry D 3 are determined from the measured temperature dependences of polarized-radiation absorption spectra. The parameters of the crystal field acting on samarium ions and the parameters of the exchange interaction between Sm3+ and Fe3+ ions are found. The anisotropy of the effective exchange interaction is shown to be substantially stronger than the magnetic anisotropy, due to a strong crystal-field-induced mixing of the ground and excited multiplets. © 2014 Pleiades Publishing, Inc

High-resolution spectroscopy, crystal-field calculations, and quadrupole helix chirality of DyFe<inf>3</inf>(BO<inf>3</inf>)<inf>4</inf>

© The Authors, published by EDP Sciences.High-resolution polarized transmission spectra of Dy Fe3(BO3)4 single crystals were investigated in broad spectral (10-23000 cm-1) and temperature (3.5-300 K) ranges. Energies of the dysprosium levels in the paramagnetic and antiferromagnetic phases were determined. On the basis of these data and preliminary calculations in the frameworks of the exchange-charge model, we determined the crystal-field and Dy-Fe exchange interaction parameters of the Dy3+ ions at sites with the point C2 symmetry corresponding to the enantiomorphic P3121 and P3221 space groups. The values of electronic quadrupole moments of the Dy3+ ions were calculated, which enabled us to interpret results of the work [Usui et al., Nature Mater. 13, 611 (2014)] on the observation of domains of different quadrupole chirality in DyFe3(BO3)4