Catalytic activity of sorbents containing metals, and nucleophilicity of alcohols activated with fluoride anion in reaction of nucleophilic substitution in 2,3-dichloronaphthazarines

In reaction of 5, 8-dihydroxy-2, 3-dichloro-6-ethyl-7-ethoxy-1,4-naphthoquinone and 6-tert-butyl-5,8-dihydroxy-2,3-dichloro-l,4-naphthoquinone proceeding on the surface of molecular sieves, calcium phosphate and carbonate, neutral alumina, or magnesium silicate with nucleophilic reagents (methanol, 2-methoxyethanol, monomethyl ethers of di- and triethylene glycols) activated with fluoride anion the yield of products decreased in this nucleophiles series. The most active catalysts among sorbents are alumina and magnesium silicate. All the sorbents are also efficient catalysts of alkoxy groups interchange.     

Modeling two-phase flows in channels and nozzles

The gas dynamics of the flow of a two-phase mixture, consisting of a gaseous phase and polydisperse liquid particles of oxides suspended in it, plays a major role in determining the thrust parameters of rocket engines and the power characteristics of MHD stations based on metallized fuels. A number of monographs and reviews have now been published that reflect the current state in this branch of continuum mechanics. Here we give the results of a numerical investigation of certain features of two-phase streams in combustion chambers, Laval nozzles, and MHD generators.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 71–81, August, 1992.     

Action of a high-power plasma flow on a transparent mechanical structure

Experimental investigations are carried out to determine the action of high-power plasma streams on a mechanical structure having a nonzero transparency factor and composed of bodies with a surface with a small radius of curvature in at least one of the principal directions. It is shown in the example of stainless steel grids and wires that the erosion of such structures under the action of a high-power plasma stream can significantly exceed the erosion of a flat solid plate. Zh. Tekh. Fiz. 67, 20–23 (February 1997)     

Synthesis and spectrophotometric study of deprotonation of octamethylporphyrin derivatives with 1,8-diazabicyclo[5.4.0]undec-7-ene in acetonitrile

Acidic properties of synthesized 5,10,15,20-tetrakis(4′-tert-butylphenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin and 5,10,15,20-tetrakis(3′,5′-di-tert-butylphenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin have been studied by spectrophotometry. Deprotonation of the intracyclic nitrogen atoms with 1.8-diazabicyclo [5.4.0]undec-7-ene in acetonitrile occurs in two steps. Deprotonation constants and ranges of the porphyrinsanionic forms existence have been determined, and influence of the peripheral substituents on acidic properties of the macrocyclic ligand has been elucidated.     

Storing energy in lithium fluoride crystals irradiated with femtosecond laser pulses

The release of energy in the form of the light sum of thermally stimulated luminescence (TSL), stored under conditions of self-focusing and the multiple filamentation of femtosecond laser radiation during the interaction between model wide-bandgap dielectric crystals of lithium fluoride is studied. It is shown that F₂ color centers are important centers of emission in the TSL process.