Wave attenuation in an elastic medium

This article examines the propagation of viscoelastic (elastic) waves in a medium consisting of two layers of finite thickness. It is found that there is a mechanical effect manifest in the monotonic dependence of the damping factor on the parameters of the system. These dependences have distinct maxima and minima, thus making it possible to optimize the damping properties of systems by varying their geometric parameters.Translated from Dinamicheskie, Sistemy, No. 4, pp. 57–62, 1985.     

Synthesis and reaction of the novel complex [AsPh4][OsCl5(H2O). X-ray structure analysis of [AsPh4][OsCl5(H2O)].2EtOH and [AsPh4][OsCl5(EtOH)].EtOH

The synthesis and characterization of the anionic mononuclear and homobinuclear osmium complexes [AsPh4][OsCl5L].xEtOH [L = H2O, x = 2 (9); L = EtOH, x = 1 (10a); L = py, x = 0 (10b)] and [AsPh4]2[Cl5Os(pyz)OsCl5] (12) (pyz = pyrazine) are described. Upon reduction in a chloride-containing medium, OsO4 (1) affords the osmium(IV) species [OsCl5(H2O)]- (2), which could be isolated by extraction with n-tributyl phosphate (TBP). Complex 9 is the first fully characterized chloroaquo complex of Os(IV). This complex is an effective starting material for the preparation of novel species, such as 10a, 10b, and 12. The X-ray structures of 9 and 10a were determined. Both compounds crystallize in the monoclinic space group P2(1)/n. 9: C28H34AsCl5O3Os, a = 10.910(4) A, b = 17.127(5) A, c = 17.555(7) A, beta = 103.77(2) degrees, V = 3186(2) A3, and Z = 4. 10a: C28H32AsCl5O2Os, a = 10.7762(2) A, b = 17.3939(1) A, c = 17.1477(3) A, beta = 103.645(1) degrees, V = 3123.45(8) A, and Z = 4. Complexes 9 and 10a crystallize with two and one molecule of EtOH and are bonded via hydrogen bridges to the H2O and EtOH ligand in 9 and 10a, respectively.     

Pyrylocyanines. 34.* pyrylocarbocyanines of asymmetrical structure with bridge groups in the chromophore

Asymmetrical carbocyanines with bridge groups in the chromophore, containing pyrylium, benzothiazolium, and pyridinium residues, were produced. The electronic and steric influence of the bridge groups on the spectral properties of the dyes was analyzed. The structure of the compounds obtained was confirmed by the data of electron spectroscopy and PMR spectroscopy.     

Precipitation Recovery of Rhenium(VII) from Aqueous Solutions with Coagulating Cationic Polyelectrolyte

Rhenium(VII) recovery from dilute aqueous solutions by coprecipitation with VA-212 cationic polyelectrolyte in the presence of nitrate ions was studied.     

Hetarenes with a bridge nitrogen atom. 6. Ambident properties of the oxazolo[3,2-a]pyridinium nucleus in reactions with nucleophiles: Prediction and experiment

We have studied the problem of ambident opening of five-membered and six-membered rings of the heteroaromatic oxazolo[3,2-a]pyridinium cation. A quantum chemical SINDO1 calculation of the energies of isomeric adducts of this cation with nucleophiles predicts preferential formation of the C₉-adduct in the case of OH and SH ions with opening of the oxazole fragment, while for nitrogen-containing nucleophiles (NH₂, NMe₂) attack at the C₍₅₎ atom is also likely with opening of the pyridine fragment. We have experimentally observed that this cation undergoes opening of the five-membered ring in reaction with NaSH, opening of the six-membered ring in reaction with piperidine, and opening of both rings in reaction with ammonia.For communication 5, see [1].M. V. Lomonosov Moscow State University, Moscow 119899. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 397–402, March, 1997.     

Natural vibrations of composite viscoelastic cylinders

Free damping spatial and axisymmetrical vibrations of short cylinders consisting of elastic and viscoelastic layers are considered. A numerical study is made of the dependence of natural frequencies and damping coefficients on the ratio of geometric cylinders.Translated from Dinamicheskie Sistemy, No. 5, pp. 55–58, 1986.