Determination of the size of particles of highly dispersed materials by low temperature nitrogen adsorption

The average size of particles of highly dispersed materials (Al₂O₃, TiO₂, Y₂O₃) is calculated from their specific surface areas. The latter is determined with the analysis of sorption capacity of materials with nitrogen at ?196°C in the ranges of relative equilibrium pressures of 0.05–0.35 (the Brunauer-Emmett-Teller method, BET) and 0.4–0.7 (the comparative method). Good agreement is obtained between results produced with the comparative method and familiar methods of analysis such as scanning and transmission electron microscopy and small-angle X-ray scattering.     

RESTRICTED LIE ALGEBRAS WITH MAXIMAL 0-PIM

In this paper it is shown that the projective cover of the trivial irreducible module of a finite-dimensional solvable restricted Lie algebra is induced from the one dimensional trivial module of a maximal torus. As a consequence, the number of the isomorphism classes of irreducible modules with a fixed p-character for a finite-dimensional solvable restricted Lie algebra L is bounded above by p ^MT(L), where MT(L) denotes the maximal dimension of a torus in L. Finally, it is proved that in characteristic p > 3 the projective cover of the trivial irreducible L-module is induced from the one-dimensional trivial module of a torus of maximal dimension, only if L is solvable.     

Synthesis of cerium dioxide sols by an ion exchange method

Finely dispersed CeO₂ hydrosol is synthesized through ion exchange in aqueous solutions of cerium chloride in the presence of anionite AV-17-8.     

Differential non-destructive image current detection in a fourier transform quadrupole ion trap

Dual-detector differential non-destructive Fourier transform detection in a quadrupole ion trap is shown to improve signal intensity and reduce noise compared with spectra recorded using a single detector. A larger area detector in each end-cap electrode is machined to fit its hyperbolic shape and so minimize field imperfections on the z-axis. Argon, acetophenone and bromobenzene spectra were recorded to allow a comparison between single- and dual-detector (differential) modes of detection and to demonstrate the improvement achieved with differential detection. Copyright 1999 John Wiley & Sons, Ltd.     

Optical properties of spherical monodisperse Y2O3-ZnO nanoparticles

Based on the developed technique for synthesizing spherical mesoporous particles of yttrium oxide with a size dispersion of 10?C15% and methods for infiltrating active components into them, spherical nanocrystalline particles of composition Y₂O₃-ZnO have been synthesized. The nanocomposite structure has been studied, and the spectra of diffuse reflection and photoluminescence of heteroparticles, as well as the stimulated emission spectra of zinc oxide excitons, have been analyzed after annealing at various temperatures. The formation of ZnO nanocrystals in Y₂O₃ sphere pores is observed during material synthesis with a single infiltration procedure. The lasing is associated with a change in the effective refractive index and local photon density of states in phosphor nanoparticles, i.e., spherical optical cavities.     

Synthesis of yttrium hydroxide hydrosols

Ion exchange of YCl₃ aqueous solutions with anion-exchanger AV-17-8 was used to synthesize yttrium hydroxide as a stable sol having average particle sizes of 3–15 nm and as a powder having specific surfaces of 50–160 m²/g.