Energetics of the thermoelastic effect in solids

The dependence of the temperature on the external adiabatic deformation is determined for a one-dimensional model of a solid — chains of atoms with an anharmonic interaction. The resulting dependences of the average kinetic and potential components of the internal energy on this deformation are compared with a model of adiabatic loading of a single oscillator. Fiz. Tverd. Tela (St. Petersburg) 40, 1548–1551 (August 1998)     

Photorefractive polymer-dispersed liquid crystals

We report observation of the photorefractive effect in functionalized polymer-dispersed liquid crystals. The photoconductive properties are provided by the polymer matrix, and the field-dependent refractive-index changes are generated by the dispersed nematic liquid-crystal droplets. A high diffraction efficiency (8%) and a high refractive-index modulation amplitude (Dn = 2 x 10(-3)) are obtained in 53- microm-thick samples with an applied field of 22 V/microm.     

ESR measurements of concentration for strong surface acceptor centers on zeolites and Al2O3 using nitroxide radical TEMPON

A method to measure concentrations of strong surface acceptor centers on aluminosilicate catalysts by their titration with a solution of TEMPON (2,2,6,6-tetramethyl-4-oxypiperidine-1-oxyl) is suggested. The concentration of these centers corresponds to that of CO test molecules for the strongest acceptor centers (_CO 2210 cm^–1) obtained using IR spectroscopy. It is shown that for ZSM-5 zeolites most of these centers are localized on their external surface.

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. - - CO (_CO 2210 cm^–1). , ZSM-5 .

     

Synthesis of 20-hydroxyecdysone 25-acetate

A scheme has been developed for the selective conjugation of 20-hydroxyecdysone (20E) at the 25- position, with the synthesis of 20E 25-acetate as an example. The proposed scheme also permits the selective, synthesis of 20E 22-esters from both lower and higher fatty acids, which opens up prospects for the creation from them of drugs with a prolonged action.Institute of Biology, Komi Scientific Center, Urals Division of the Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, Vol. 33, No. 1, pp. 74–78, January–February, 1977.     

Catalytic activity of iron hydroxides and manganese hydroxides in the deoxygenation of water

Catalysts prepared by the modification of FIBAN K-4 and FIBAN X-1 fibrous ion exchangers with the hydroxides of iron and manganese were developed and tested in a water deoxygenation process. It was established that the samples obtained by the supporting of Fe(III) hydroxide onto the FIBAN X-1 ampholyte were most effective. The conclusion that the high activity of the catalytic system is caused by the formation of a mixed phase of Fe(II) and Fe(III) hydroxides of the spinel type containing mobile (weakly bound) lattice oxygen was made. A reaction scheme was proposed to explain the reaction mechanism.     

Application of resonant detectors in M?ssbauer spectroscopy

The application of resonant detectors in M?ssbauer spectroscopy allows us to increase resolution and sensitivity and thus to expand the information potential of this method. In this work, the particulars of applying resonance detection are described and its advantages are demonstrated experimentally in comparison with conventional methods of detection.     

Catalytic Synthesis and Study of Carbon–Graphene Structures

Russian Journal of Physical Chemistry A - The optimum conditions of production, structure, and features of the formation of carbon–graphene composites on nickel–graphene catalysts are...     

Applying an improved phonon confinement model to the analysis of Raman spectra of germanium nanocrystals

The improved phonon confinement model developed previously [11] is applied for definition of germanium nanocrystal sizes from the analysis of its Raman scattering spectra. The calculations based on the model allow determining the sizes of germanium nanocrystals more precisely from the analysis of their Raman spectra. In some cases, the comparative analysis of Raman data and electron microscopy data is carried out, and good agreement is observed.     

Synthesis, growth and optical spectroscopy studies of BaBiBO4 and CaBi2B2O7 crystals

Single-crystalline species of the novel compounds BaBiBO₄ and CaBi₂B₂O₇ with Pna2₁ structure were successfully grown by the top-seed solution growth (TSSG) method and solid-state recrystallization, respectively. X-ray diffraction methods were used to confirm the symmetry of the crystal structure and to determine unit cell parameters. Normal-mode classification and assignment were performed from the results of polarized Raman and IR absorption measurements on the obtained crystals. The high-frequency part of the vibrational spectra of both materials (580–1400 cm^?1) is reminiscent of the normal modes of the isolated [BO₃]^3? group. The expected crystal-field induced changes in these modes from group-theoretical considerations provide important clues for the normal-mode assignment of the high-frequency spectral lines.     

Strong laws for certain types of U-statistics based on negatively associated random variables

We establish the Marcinkiewicz-Zygmund-type strong laws of large numbers for certain class of multilinear U-statistics based on negatively associated random variables.