Comparison between the measured and calculated reactivity in measuring the effectiveness of the emergency protection at the stage of physical start-up of unit no. 3 at the Kalinin nuclear power plant

This paper presents comparisons between the effectiveness of the emergency protection under both stationary and nonstationary formulations calculated with the use of the RADUGA-7.5 package [1] and experimental data obtained in measuring the ??weight?? of the emergency protection in the process of physical start-up of the VVER-1000 reactor of unit no. 3 of the Kalinin NPP. On the basis of the results obtained, recommendations are given on comparing the measured and calculated reactivity and parameters determined by using its value.     

Synthesis and studies of magnesium hexafluorozirconates MgZrF<Subscript>6</Subscript> · <Emphasis Type="Italic">n</Emphasis>H<Subscript>2</Subscript>O (<Emphasis Type="Italic">n</Emphasis> = 5, 2, 0)

Crystalline magnesium hexafluorozirconate MgZrF₆ · 5H₂O isostructural to MnZrF₆ · 5H₂O, and having a chain-like structure, was synthesized and studied. According to thermogravimetry, the compound undergoes stepwise dehydration in the temperature range of 50–420°C to give the stable phase MgZrF₆ · 2H₂O and the final product MgZrF₆ isostructural to the cubic modification of MZrF₆ (M = Cu, Fe). The vibrational spectra of the initial compound and the dehydration products are analyzed and the structures of the compounds are considered.     

Luminescence and magnetic properties of mixed-ligand europium trifluoroacetates

The luminescence and magnetic properties of mixed-ligand europium trifluoroacetates with nitrogen- and phosphorus-containing neutral ligands [Eu(TFA)₃ · 3H₂O]₂ and Eu(TFA)₃ · 2D · nH₂O were studied (here TFA is the trifluoroacetic acid anion, and D is Phen (1,10-phenanthroline), n = 1; DMF (dimethylformamide), n = 1; or TPPO (triphenylphosphine oxide), n = 3). The molar magnetic susceptibility increased in the series of complex compounds Eu(TFA)₃ · 2Phen · H₂O < [Eu(TFA)₃ · 3H₂O]₂ < Eu(TFA)₃ · 2DMF · H₂O < Eu(TFA)₃ · 2TPPO · 3H₂O. Correlations were found between the luminescent and magnetic characteristics of the complex compounds.     

Searching for preferential arrival directions of ultrahigh-energy cosmic rays on the Moscow State University EAS array

There is evidence for possible clustering in the arrival directions of extensive air showers (EASs). A program for analyzing EAS arrival directions has been developed to investigate this problem and the database of the Moscow State University EAS array for 1982–1989 has been analyzed. The distributions in equatorial coordinates have been derived for cosmic rays with energies E ≥ 2 × 10¹⁵ eV and zenith angles <40°. The uniformity of the derived distributions is verified using various statistical tests.     

Ionic mobility,structure, and conductivity of 45ZrF<Subscript>4</Subscript>-35BiF<Subscript>3</Subscript>-20CsF glass according to <Superscript>19</Superscript>F NMR,IR, Raman,and impedance spectroscopy

¹⁹F NMR, IR, Raman and impedance spectroscopy are used to study the ionic mobility, structure, and conductivity of 45ZrF₄-35BiF₃-20CsF bismuth fluorozirconate glass. With the increase in temperature from 150 K to 500 K the fluorine-containing groups pass from the rigid lattice to local movements (reorientations), and then to diffusion. According to the results of IR and Raman spectroscopy, the lattice of this glass consists of ZrF₈ polyhedra linked by their vertices into chains. The glass has high ionic conductivity: σ ≈ 1.8×10⁻⁴ S/cm in a temperature range of 480–485 K.     

Reconstruction and crosstalk of protein-protein interaction networks of Wnt and Hedgehog signaling in Drosophila melanogaster

In the last few years, researchers have an intense interest in the evolutionarily conserved signaling pathways which have crucial roles during embryonic development. The most intriguing factor of this interest is that malfunctioning of these signaling pathways (Hedgehog, Notch, Wnt etc.) leads to several human diseases, especially to cancer. This study deals with the β-catenin dependent branch of Wnt signaling and the Hedgehog signaling pathways which offer potential targeting points for cancer drug development. The identification of all proteins functioning in these signaling networks is crucial for the efforts of preventing tumor formation. Here, through integration of protein-protein interaction data and Gene Ontology annotations, Wnt/β-catenin and Hedgehog signaling networks consisting of proteins that have statistically high probability of being biologically related to these signaling pathways were reconstructed in Drosophila melanogaster. Next, by the structural network analyses, the crucial components functioning in these pathways were identified. The proteins Arm, Frizzled receptors (Fz and Fz2), Arr, Apc, Axn, Ci and Ptc were detected as the key proteins in these networks. Futhermore, the hub protein Mer having tumor suppressor function may be proposed as a putative drug target for cancer and deserves further investigation via experimental methods. Finally, the crosstalk analysis between the reconstructed networks reveals that these two signaling networks crosstalk to each other.     

Intramolecular mobility and phase transitions in ammonium oxofluoroniobates (NH4)2NbOF5 and (NH4)3NbOF6, a NMR and DFT study

Molecular structure, ionic mobility and phase transitions in six- and seven-coordinated ammonium oxofluoroniobates (NH₄)₂NbOF₅ and (NH₄)₃NbOF₆ were studied by ¹⁹F, ¹H NMR and DFT calculations. Equatorial fluorine atoms (F_eq) in [NbOF₅]²⁻ and [NbOF₆]³⁻ are characterized by high ¹⁹F NMR chemical shifts while axial fluorine atoms (F_ax) have those essentially lower. The high-temperature ionic mobility in (NH₄)₂NbOF₅ does not stimulate the ligand exchange F_eq ↔ F_ax, whereas it is observed in (NH₄)₃NbOF₆ as pseudorotation typical for seven-coordinated polyhedra. The transformation of pentagonal bipyramidal structure (BP) of [NbOF₆]³⁻ into capped trigonal prismatic (CTP) one takes place during the phase transition (PT) at 260 K. The PT of order-disorder type in (NH₄)₂NbOF₅ is accompanied by transition of anionic sublattice to a rigid state. The ¹⁹F and ¹H NMR data corroborate the independent motions of NH₄ groups and anionic polyhedra in (NH₄)₂NbOF₅ while they are coordinated in (NH₄)₃NbOF₆.