Yu. V. Gerasimova

Infrared absorption investigation of the role of octahedral groups upon the phase transition in the Rb 2 KMoO 3 F 3 crystal

The infrared absorption spectra of the oxyfluoride Rb2KMoO3F3 have been measured in the frequency range corresponding to stretching vibrations of the Mo-O anion octahedron with the purpose of clarifying their role in the phase transition. A semi-empirical calculation of two possible configurations of quasioctahedral MoO3F3 groups has been performed. The results of the investigations have demonstrated that some octahedra in the crystal structure change the local symmetry from C3v to C2v due to the phase transition (T = 197 K).

A Raman scattering study of the phase transition in the (NH4)3WO3F3 oxyfluoride

The Raman scattering spectra of polycrystalline samples of the (NH4)3WO3F3 perovskite-like oxyfluoride were measured at frequencies of 70–3600 cm−1 in the temperature range 93–323 K, including the transition from the orientationally disordered cubic phase to the low-symmetry phase. Transitional anomalies in the spectral parameters were revealed in the frequency ranges of internal vibrations of the ammonium ions and WO3F3 octahedral groups. An analysis of the experimental results allowed the conclusion that the phase transition under study is associated primarily with the ordering of the octahedral groups.

Infrared absorption spectra of a Nd0.5Ho0.5Fe3(BO3)4 crystal

Infrared absorption spectra of a Nd0.5Ho0.5Fe3(BO3)4 crystal in the spectral range of 30–1700 cm–1 have been measured at temperatures from 6 to 300 K. The experimental spectra have been analyzed based on the semiempirical calculation of the lattice dynamics and the analysis of correlation diagrams of borate complexes. No changes associated with structural phase transitions have been detected in the temperature range of measurements; the effect of magnetic ordering on the infrared absorption spectra has not been observed.

Influence of the substitution of the central Me atom in ammonium oxyfluorides on phase transitions: IR spectroscopy study

Comparative investigations of infrared absorption spectra of ion-molecular crystals of the ammonium-containing oxyfluorides (NH4)3WO3F3 and (NH4)3MoO3F3 have been performed. It has been found that the parameters of the vibrational spectra exhibit anomalies in the ranges of internal vibrations of the MeO3F3 octahedral groups and ammonium ions near the phase transition temperatures. A comparative analysis of the IR spectra allows us to affirm that the studied phase transition in (NH4)3WO3F3 is primarily associated with the ordering of octahedral groups, whereas in (NH4)3MoO3F3, it is mainly due to the ordering of ammonium groups and the distortion of ammonium ions by the crystal environment.

Structure of oligomeric proanthocyanidines from Hedysarum thienum roots studied by thiolysis and MALDI-TOF MS

Oligomeric proanthocyanidines from Hedysarum theinum roots that were cleaved by benzylmercaptan were shown to be heterogeneous mixtures consisting of prodelphinine and procyanidine structural units with the former dominating. Fractionation of oligomeric proanthocyanidines on polyamide and MCI gel CHP20P sorbent isolated fractions containing primarily mixtures of di- and trimeric, tri- and tetrameric, or tetra- and pentameric proanthocyanidines. Analysis by mass spectrometry (MALDI-TOF) showed that fractions of trimers and tetramers contained more proanthocyanidines with a single A-type bond than fractions of dimers and trimers.

Structural, spectroscopic, and thermophysical investigations of the oxyfluorides CsZnMoO3F3 and CsMnMoO3F3 with the pyrochlore structure

The structure, infrared and Raman spectra, heat capacity, and thermal expansion have been investigated. It has been shown that, down to liquid-helium temperatures, the cubic pyrochlore structure of the CsMnMoO3F3 and CsZnMoO3F3 oxyfluorides remains stable. The influence of cation substitution on individual features of the properties of the oxyfluorides has been analyzed.

A raman scattering study of the phase transition in the ammonium oxyfluoride (NH4)3TiOF5

Raman spectra of a polycrystalline sample of the perovskite-like oxyfluoride (NH4)3TiOF5 are measured in the frequency region 100–3600 cm−1 at temperatures ranging from 91 to 370 K under hydrostatic pressures of up to 9 GPa, which include the range of the phase transition from the orientationally disordered cubic phase to the low-symmetry phase. Anomalies in the spectral parameters due to the phase transition are revealed in the range of vibrations of TiOF5 octahedral groups.

A study of complexation between crystalline trans-[Pd(H2O)2(NO3)2] and acetylacetone

Complexation between crystalline trans-[Pd(H2O)2(NO3)2] and acetylacetone was studied. The complexes Pd2(Acac)2(μ-NO3)2(I) and Pd2(Acac)2(μ-Acac)(μ-NO3)(II) were obtained and examined by elemental analysis, X-ray powder diffraction analysis, differential scanning calorimetry, simultaneous thermal analysis, mass spectrometry, and vibrational spectroscopy.

Magnetic properties, magnetoresistance, and Raman spectra of CuVxCr1 − xS2

The results of investigations of the magnetic and Raman spectra, magnetic properties, and magnetoresistance of vanadium-substituted chromium copper disulfides CuVxCr1 − xS2 (x = 0.1) are presented.

Biochemical and immunological markers of insufficiency of blood circulation in children with cardiomyopathies

Complex clinical-laboratory investigation of children with congestive heart failure developed on the basis of dilated cardiomyopathy and hypertrophic cardiomyopathy has been carried out. The development of congestive heart failure in children with cardiomyopathy was accompanied by changes in activity of creatine phosphokinase, MB isoform of creatine phosphokinase, and also blood serum lactate, neopterin, TNF-α, interleukin-2 (IL-2), interleukin-6 (IL-6), and the soluble receptors for IL-2 and IL-6 (sIL-2R, sIL-6R).The energy deficit in patients with congestive heart failure is associated with pronounced impairments of expression of neopterin, TNF-α, IL-2, IL-6 and their receptors. The role of cytokines in formation of dysregulation processes is analyzed at the level of intercellular and organ local interactions. A cascade of multiple biochemical and molecular processes including impairments of membrane integrity and ion transport, apoptosis, proteolysis followed by fibrosis of myocardium finally cause myocardial remodeling, the development, chronization and progression of congestive heart failure in children with cardiomyopathy.