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2015, №1

pp. 3-8

Articles

Synthesis of Glycyrrhetinic Acid Monoglycoside by Hydrolysis of Glycyrrhizic Acid in Subcritical Water

O.V. Filonova, A.V. Lekar, S.N. Borisenko, E.V. Maksimenko, E.V. Vetrova, N.I. Borisenko, V.I. Minkin.

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Key words: ammonium glycyrrhizinate, glycyram, glycyrrhizic acid, glycyrrhetinic acid, monoglycoside of glycyrrhetinic acid, electrospray ionization mass spectrometry, HPLC-MS, subcritical water

A method for synthesis of glycyrrhetinic acid monoglycoside by hydrolysis of glycyrrhizic acid in subcritical water at temperatures between 100 and 300 °C is developed. The maximum yield of the target product is obtained at 160 °C.

2015, №1

pp. 9-18

Articles

Luminescence of Nanocomposites Obtained Using SCF Impregnation of Polymer Powders by CdSe Quantum Dots

A.O. Rybaltovskii, Yu.S. Zavorotny, N.V. Minaev, V.K. Popov, D.S. Rubashnaya, P.S. Timashev.

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Key words: polymer nanocomposite, supercritical carbon dioxide, quantum dots, photoluminescence, polytetrafluoroethylene, low-density polyethylene, diffusion embedding

Luminescence of composites based on quantum dots CdSe embedded into low-density polyethylene (LDPE) and polytetrafluoroethylene (PTFE) powders using supercritical carbon dioxide is studied. It is shown that thermal treatment of the resulting powders in air in the case of LDPE causes the CdSe photoluminescence band shift to shorter wavelengths, but in the case of PTFE — to longer wavelengths with simultaneous decrease of integral luminescence intensity. The behavior of photoluminescence bands under near UV radiation in both cases is determined by photo-oxidation processes on the CdSe nuclei.

2015, №1

pp. 19-34

Articles

Key words: statistical physics, critical phenomena, molecular spectra theory

Careful analysis of CARS-spectroscopy data for carbon dioxide Fermi-dyad shows that critical density variance must not exceed 0.4 and the lifetime of critical density fluctuations is not less than 10 ns. To comprehend the experimental data, the contribution of critical fluctuations to the spectral line width is evaluated taking into consideration their lifetime.

2015, №1

pp. 35-60

Articles

Key words: temperature, pressure, density, concentration, phase, fluid, equation of state, compressibility factor, reduced parameters

The results of thermal and thermodynamic properties (diagrams of state) calculation of water-aliphatic alcohol (methanol, ethanol, n-propanol) systems in liquid and vapor phases, as well as in the state of supercritical fluid are presented. They are based on the equation of state that represents the compressibility factor as power series of reduced density (ω = ρ/ρcr) and temperature(t = T/Tcr)
\(Z=\frac{\rho}{RT\rho_m}=1+\sum_{i=1}^{m}\sum_{j=0}^{n_i}\frac{a_{ij}\omega^i}{\tau^j}\)
and describes the experimental р, ρ, Т, х-relations with an average relative error 1.2%.

2015, №1

pp. 61-69

Articles

Key words: ethanol, fuels, hydrolysis, gasification, saccharification, supercritical fluids

Publications devoted to the application of supercritical fluids to deep biorefinery of vegetable raw materials for production of wide range of products, such as ethanol, liquid and gaseous fuels, sugars, organic acids, and oils are reviewed and analyzed. The specific features of the supercritical fluid technologies and their advantages in comparison with the existing traditional methods of biorefinery of vegetable raw materials are demonstrated.

2015, №1

pp. 70-77

Articles

Manufacturing of Porous Ultrahigh Density Polyethylene Using Subcritical Water

D.Yu. Zalepugin, A.V. Maksimkin, N.A. Tilkunova, I.V. Chernyshova, F.S. Senatov, M.I. Vlasov.

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Key words: ultrahigh density polyethylene, subcritical water, porosity, implant

The method of subcritical water extraction of NaCl from ultrahigh density polyethylene (UHDPE) samples is developed as a stage in the manufacturing of porous polymer — a promising material for implant production. Optimal process parameters were determined as follows: pressure 250 atm, temperature 120 °С, water flow rate 3 g/min. This method provides with a tenfold reduction of salt extraction time (from 10 to 1 h). The main pore diameter of UHDPE determined by scanning electronic microscopy ranges from 80 to 700 µm.

2015, №1

pp. 78-85

Articles

Key words: phase diagrams, solubility, liquid-liquid immiscibility, critical phenomena

The system LiOH—H2O is characterized by the immiscibility phenomena both in equilibrium with vapor and solid saturated solutions or without solid phase. Solubility of LiOH increases as a result of immiscibility phenomena at ∼355 °С and further increases above this temperature up to the melting point. The immiscibility region (g - l1 - l2) is terminated by the critical phenomena (g = l1 - l2) at ∼390 °С. A separation of liquid phases is observed at elevated pressures (at ∼39 MPa) and temperatures up to 425 °C.