Structural study of Pb(Mg1/3Nb2/3)O3 at low temperatures

The structure of the relaxor ferroelectric Pb(Mg_1/3Nb_2/3)O₃ crystal was studied with the X-ray single crystal diffraction at 110, 224 and 293 K. The remarkable redistribution of the reflections intensities at low temperatures was observed. The structure of the low temperature phase is described with the model of the substantially nonuniform displacements of the lead ions using the derived analytical expression of the scattering form-factor. The structure refinement shows the good agreement between the model and the experimental data at low temperatures.     

Pulsational characteristics of two-cassette model of boiling-water reactor

Conclusions On a large-scale two-cassette model of the natural-circulation loop of a reactor with vertical dimensions and reduced hydraulic-drag coefficients of the basic loop elements that are close to the full-scale values, an experimental investigation has been conducted, with the following conclusions:With design parameters of the heat carrier, the specific thermal stress of the fuel elements, and the discrepancy coefficients of the pile power, the zone of hydrodynamic instability is characterized by the values ; liquidation of total-loop pulsations of the heat-carrier flow rate entails vapor condensation under the water level in the reactor; total liquidation of the pulsations requires, in addition, the introduction of disks at the input to each pile; the reduced hydraulic-drag coefficient _re of the disk must be no less than 0.8 of the sum of _re for the pile and the ITS.Translated from Atomnaya Énergiya, Vol. 69, No. 2, pp. 87–92, August, 1990.     

Effect of silver additions on the structural properties and phase composition of TiO<Subscript>2</Subscript>/Ag composites

We have studied the effect of silver nitrate additions on the anatase–rutile transformation of titanium dioxide in TiO₂/Ag composites at low temperature (500°C). The structure and phase composition of the composites with different Ag(I) concentrations have been determined by X-ray diffraction and transmission electron microscopy. The results demonstrate that the percentage of rutile increases with increasing Ag(I) ion concentration, reaching 60 wt %. A mechanism of the anatase–rutile transformation in the composites has been proposed.     

Fully automated chip-based mass spectrometry for complex carbohydrate system analysis

Carbohydrates represent a major class of biopolymers, which occur in nature either as oligosaccharides or glycoconjugates, in which the sugar moiety is linked to proteins or lipids. The significance of mass spectrometry for highly sensitive analysis of complex carbohydrates increased after the introduction of the electrospray ionization and matrix assisted laser desorption/ionization methods and the possibility of tandem MS for sequencing of single molecular species in complex mixtures. Rapid and sensitive characterization of carbohydrates in biological systems by automated nanoscale liquid delivery and chip-based electrospray interface techniques have not been developed so far. In this contribution, the implementation and optimization of a fully automated chip-based nanoelectrospray assembly (NanoMate system), operating in the negative ion mode, in combination with QTOF-tandem MS for mapping/sequencing and computer-assisted structure assignment for carbohydrate components in complex mixtures is presented.