Relaxing local modes and the theory of low-frequency Raman scattering in glasses

Raman scattering in glasses is investigated theoretically. The experimental Raman spectra of glasses exhibit a low-frequency peak (at ～10 cm^?1) that, as a rule, is attributed to vibrational modes of nanometer-sized structural units (nanocrystallites). It is established that the elastic moduli of nanocrystallites must necessarily be dependent on their sizes due to the Laplace pressure effect. A theory of the low-frequency peak is constructed using a realistic size distribution function of nanocrystallites with allowance made for the Laplace pressure effect and the dissipation of vibrational energy. Within this theory, the shape of the low-frequency peak and its evolution with temperature can be analyzed quantitatively. The proposed approach offers a physical interpretation of the experimental data and provides insight into the relation of the characteristic nanocrystallite sizes to the elastic moduli and surface tension coefficients of materials.     

Structure and electrical and mechanical properties of (Pd87.3W12.7)1−xNix

The effect of composition and temperature on the properties of the alloy PdV-20 doped with nickel was investigated. It was established that the microhardness, electroresistivity, and the normal elasticity modulus depend nonmonotonically on the content of nickel, and also that these quantities are affected significantly by the past thermal history of the samples. The results' are discussed, taking into account the nature of their intrinsic short-range order structure.Translated from Izvestiya Vysshikh. Uchebnykh Zavedenii, Fizika, No. 5, pp. 42–46, May, 1991.     

Stereochemistry of the synthesis of 1,2,3,4-tetrahydrocinnolines from aryldiazenium salts and olefins

It follows from the PMR spectra that the reaction of 1-methyl-, 1-phenyl-, 1-ethyl-,1-phenyl-, and 1,1-diphenyldiazenium salts with cis- and trans-d-styrenes, which leads to the corresponding 3-d-4-phenyl-1,2,3,4-tetrahydrocinnolines, takes place with retention of the configuration in the starting styrenes. It is therefore proposed that this reaction be regarded as a special case of [4⁺_s + 2_s]-cycloaddition.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1658–1661, December, 1977.     

Synthesis and structure of 5-hydrazino- and 5-hydroxyamino-3-aryl-2-pyrazolines and-2-isoxazolines

It was established by the methods of ¹H and ¹³C NMR spectroscopy that the oximohydrazones and bis(hydrazones) of aroylacetic aldehydes exist in the form of the corresponding 5-hydrazino- and 5-hydroxyamino-3-aryl-2-pyrazolines and -2-isoxazolines. The features of the aromatization of these compounds to the corresponding pyrazoles and isoxazoles were studied. Data on the mass-spectral study of the 5-hydroxyamino-2-pyrazoline-5-hydrazino-2-isoxazoline tautomerism in the gas phase are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 927–935, July, 1989.     

Amidrazones in the synthesis of heterocycles (review)

Data on the synthesis, on the basis of amidrazones, of mono-, di-, tri-, and tetrazoles, diazoles containing boron, oxygen, silicon, phosphorus, and sulfur atoms in the ring, mono-, di-, tri-, and tetrazines, triazepines, and benzotriazepines, as well as a number of condensed heterocyclic derivatives, are systematized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–887, July, 1989.     

5(3)-Hydroxyisoxazolidin-3(5)-ones and 5-hydroxy-pyrazolidin-3-ones and their ring-chain tautomerism

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 280–281, February, 1991.     

1,2,4-Triazine and triazole derivatives from α-keto acids and thiosemicarbazides

Thiosemicarbazides of 2-hydroxyphenylglyoxylic acid, which, depending on the conditions, undergo cyclization to interconvertible 5-(2-hydroxyphenyl)-6-oxo-1,2,4-triazine-3-thiones or (2-hydroxy-benzoyl)-²-1,2,4-triazoline-5-thiones, are formed by the action of thiosemicarbazide and its homologs on coumarindione. The thiosemicarbazones of 2-hydroxyphenylglyoxlyic and other 2-substituted phenylglyoxylic acids undergo cyclization to 6-(2-hydroxyphenyl)-5-oxo-1,2,4-triazine-3-thiones.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp, 116–121, January, 1977.     

Thermodynamics of the Interaction of the Ni<Superscript>2+</Superscript> Ion with the L-β-Phenyl-α-Alanine Anion in Aqueous Solution

The enthalpies of the interaction of the L-β-phenyl-α-alanine anion with the Ni²⁺ ion in aqueous solution were measured by calorimetry for the ionic strength I = 0.5, 1.0, and 1.5 (KNO₃ as a supporting electrolyte) at 298.15 K. The thermodynamic parameters of the formation of Ni(II) complexes with phenylalanine in aqueous solution were calculated. The effect of the ligand structure on the thermodynamic parameters of complexation reactions in solution was discussed.     

Mutarotation of fructose thiosemicarbazone and its 4-substituted homologs

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 565–566, April, 1992.     

Cyclic structure of the β(γ)-hydroxy-(mercapto)alkylimines of aldoses

In solutions in DMSO-d₆, the products from the condensation of ethanolamine and 1,2- and 1,3-aminopropanols with aldoses are mixtures of the - and -pyranose forms, whereas the -mercaptoethylimines of aldoses have the 1,3-thiazolidine structure. Glucose -mercaptoethylimine is characterized by ring-chain tautomerism involving the -pyranose and diastereomeric 1,3-thiazolidine tautomers.Military-Medical Academy, St. Petersburg, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1068–1071, August, 1998.