Observation of superluminal wave-front propagation at the shadow area behind an opaque disk

We demonstrate in theory and experiment superluminal properties of optical field propagation in the shadow area behind an opaque disk (Poisson's spot). The wave front of the field in the shadow zone is initially delayed with respect to the unperturbed field. This phase shift gradually diminishes along the optical path and therefore ensures variation of the phase velocity of the field at the axis. A resulting excess of about cx10(-5) was detected.     

Stabilized Zirconia-Based Nanostructured Powders for Solid-Oxide Fuel Cells

High-purity uniform powders of zirconia-based solid electrolytes stabilized with yttria (4 and 8 mol %) are synthesized by co-precipitation with subsequent annealing at different temperatures. The obtained powders were studied using X-ray analysis and transmission electron microscopy; the specific surface area was measured by nitrogen adsorption. The stabilized zirconia powder sintering was studied over temperature range from 1000 to 1600°C. The ionic conductivity of samples containing 8 mol % of yttria was 0.06–0.07 S/сm, that is comparable with that obtained with commercial solid electrolytes.     

The effect of oligomeric electrolytes on the aggregative stability and rheological properties of aqueous mineral suspensions

Oligomeric electrolytes of benzene and naphthalene series are synthesized, and the effects of chain length and hydrophilic group position in their molecules on not only the aggregative stability but also rheological and electrokinetic properties of concentrated mineral suspensions are studied. On the basis of the data of adsorption experiments, a parallel orientation of oligomer molecules on the surface of dispersed phase particles is revealed. By the sedimentation and electron microscopy techniques, it is established that, at the optimal concentration of oligomers, systems display aggregative stability. It is shown that the plasticizing effect of oligo-electrolytes is due to the combined action of electrostatic and adsorption-solvation factors.     

Manifestation of the rotational Doppler effect by use of an off-axis optical vortex beam

We report what is to our knowledge the first all-optical detection of the frequency beats between Gaussian and Laguerre-Gaussian LG0(1) modes in their axial superposition, caused by the rotational Doppler effect. The relation between the observable off-axis optical vortex rotation and the rotational frequency shift of the Laguerre-Gaussian component is ascertained. The results can be used as a physical basis for recognition of Laguerre-Gaussian mode spectra along their orbital angular momenta.     

Enthalpies of dissolution of propylene carbonate,acetonitrile, and 1,4-dioxane in mixtures of water with acetone or dimethyl sulfoxide

Enthalpies of dissolution of acetonitrile, propylene carbonate, and 1,4-dioxane in mixtures of water with acetone or DMSO were measured in the whole concentration range of the mixed solvents. Standard enthalpies of dissolution and enthalpies of transfer of solutes from water to its mixtures with acetone or DMSO were determined. In the region of small proportions of the nonaqueous component, the enthalpy of cavity formation in the mixed solvent makes the main contribution to the variation of the enthalpy of dissolution. An increase in the proportion of the nonaqueous component leads to competition between the contributions of cavity formation and specific interaction between the solute and the solvent during solvation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1747–1752, September, 1995.     

Observation of the rotational doppler effect for optical beams with helical wave front using spiral zone plate

A rotating spiral zone plate was used to implement and measure the rotational Doppler effect for plane-polarized optical beams with helical wave front (optical vortices). The frequency shift was analyzed in terms of energy exchange between the beams and moving optical elements.     

Enthalpies of Mixing and State of Components in Aqueous-Organic Mixtures with Nets of Hydrogen Bonds

The enthalpies of mixing of water with glycerol over the entire composition range were determined at 298.15 K. The partial excess enthalpies of the components of mixtures of water with glycerol, ethylene glycol, 1,2- and 1,3-propylene glycol, and formamide were estimated and used for examining solvation and the state of water and the organic components in the solutions. The composition of the solvation shells of the components of the mixtures were shown to depend on the nature and structure of the organic solvent.