High-temperature heat capacity of TbFe3(BO3)4

The molar heat capacity of TbFe₃(BO₃)₄ in the temperature range of 346–1041 K has been measured by differential scanning calorimetry. It has been found that the C _p = f(T) curve does not show extremes. The thermodynamic properties of the oxide compound have been determined from the experimental data.     

Heat capacity of oxides in the Bi2O3-SiO2 system

The high-temperature heat capacity of Bi₄Si₃O₁₂, Bi₂SiO₅, and Bi₁₂SiO₂₀ has been investigated. It has been found that there is a correlation between the specific heat C _p ⁰ (298 K) and the composition of oxides in the Bi₂O₃-SiO₂ system.     

The Properties of Zr,Ti, Al and Si Nitride-Based Multilayer Coatings Obtained By Cathodic Arc Plasma Deposition

Russian Physics Journal - The paper investigates the cathodic arc plasma deposition of multilayer ZrTiN and ZrTiAlSiN coatings with the maximum hardness of 28 and 29 GPa, respectively. When the...     

Electron-beam surface treatment of alloys based on titanium, modified by plasma from an electrical explosion of conducting material

We present the results from investigating the phase composition, structure, and properties of surface layers of titanium alloys subjected to combined treatment that includes plasma alloying the electric explosion of a carbon fiber with a quantity of TiB₂ powder and subsequent irradiation with a high-intensity electron beam. The formation of a multilayer, multiphase structure in the submicro- and nano-sized ranges is observed. It is shown that the properties of a alloyed layer exceed those of a bulk sample many times over.     

High-temperature heat capacity of the BiFeO3 multiferroic

Data on the heat capacity of the BiFeO₃ multiferroic have been obtained within a broad temperature interval. Correlation has been established between the composition of the Bi₂O₃-Fe₂O₃ pseudobinary system and the specific heat capacity of the oxide compounds.     

Free-radical generation mechanism and antimalarial activity of cyclohexyl endoperoxides

A kinetic analysis has been carried out for a cascade of intramolecular oxidation reactions of free radicals generated in the redox reactions of substituted cyclohexyl endoperoxides (15 compounds) with the Fe²⁺ ion. Each radical conversion reaction has been characterized by its enthalpy, activation energy, and rate constant. Kinetic characteristics have been calculated by the intersecting parabolas method. Depending on their structure, cyclohexyl endoperoxides generate one to three radicals. There is a linear empirical correlation between the number of radicals generated by a peroxide and its molar antimalarial activity (IC ₅₀/M, where M is the molar mass of the peroxide). The peroxides that generate no more than one radical show no antimalarial activity.     

Chromium(II) Complexes with Hydroxyethylidenediphosphonic Acid

The complex formation of chromium(II) with hydroxyethylidenediphosphonic acid (HEDP, H₅L) in an aqueous solution is studied by spectrophotometry. The pH region is determined where the HEDP complexonates of chromium(II) are stable. The effect of pH on the complexation and the composition of the coordination sphere of the complex ions is shown. The optimum conditions for the practical application of HEDP as a stabilizing ligand are chosen. The instability constants for tetra-, tri-, di-, and monoprotonated and neutral chromium(II) hydroxyethylidenediphosphonate complexes were calculated, whose pK were found to be 1.21, 2.43, 6.87, 12.60, 19.40, respectively. A new complex of chromium(II), Na₄[Cr(H₂L)₂ · 2H₂O] · 4H₂O, was isolated from a solution and characterized using elemental, IR spectroscopic, and thermographic analyses.     

Comparison of Extractive Capacities of Systems Based on Sulfonol,Sodium Dodecyl Sulfate,or Alkyl Benzene Sulfonic Acid

Russian Journal of Applied Chemistry - Effect of organic complexing reagents: diantipyrylmethane, diantipyrylbutane, diantipyrilheptane, 1,10-phenanthroline, and 1,2,3-benzotriazole, on the phase...     

Reactions of Chloroethynylphosphonates with 2-Aminoquinoline and 1-Aminoisoquinoline

Russian Journal of General Chemistry - The reactions of chloroethynylphosphonates with 2-aminoquinoline and 1-aminoisoquinoline proceeded chemo- and regioselectively to form novel fused tricyclic...     

Weak-pulse transparency enhancement in an optically dense three-level medium induced by a 2π pulse in a neighboring transition (V-scheme)

The coherent V-configuration interaction between an optically dense resonantly-absorbing three-level medium (neon) and two ultrashort superradiance pulses with converging wave fronts is investigated experimentally and theoretically. Both separate and combined propagation of pulses with wavelengths λ ₁=614.3 nm (strong field, θ ₁⩾π) and λ ₃=594.5 nm (weak field, θ ₃≈/20) are studied. For propagation of a separate strong-field pulse, supertransparency of the absorbing medium was observed, which is associated with the generation of a soliton-like pulse at the difference frequency (Δν≈1700 MHz) and the dispersion-diffraction stabilization effect. Under these conditions a weak-field pulse is completely absorbed. Combined propagation of the pulses leads to novel effects. A below-threshold pulse (weak field) was observed to pass through the absorber while interacting coherently with a strong-field pulse at a neighboring transition. It is shown theoretically that absorption of the weak pulse is reduced for two reasons: first, as a result of incoherent transparency of the resonance transition caused by emptying of the lower level by the field of the strong pulse, and second, as a result of coherent transfer of polarization between the upper levels via the two-photon processes. When the conditions for combined propagation are met, the latter mechanism ensures inversionless amplification of a weak pulse over a wide band of frequencies. In this case, the gain can even exceed the linear absorption coefficient in absolute value. A difference in propagation velocities of the weak and strong pulses was recorded experimentally, along with a shift in the carrier frequency of the weak field towards the red (≈600 MHz). A mechanism for transfer of phase modulation from a strong pulse to a weak pulse via the common lower level is discussed theoretically. Zh. éksp. Teor. Fiz. 113, 71–88 (January 1998)