Specific ionic conduction in poly[oligo (oxyethylene glycol) methacrylate] (PMEO)–Li salt complexes under high‐pressure CO2

We measured the ionic conductivity of amorphous poly[oligo (oxyethylene glycol) methacrylate] (PMEO)–lithium salt complexes under a CO₂ pressure varying from 0.1 to 20 MPa. The pressure dependence of the conductivity was positive, and the conductivity was higher than that under an inert gas such as N₂. The ion‐conductive behavior has been modeled using both the Vogel–Tammann–Fulcher (VTF) equation and activation volume theory. The calculated parameters of the VTF equation show that CO₂ that had permeated into the PMEO matrix acts as solvent molecules to dissolve ions and lower the glass transition temperature at high pressures. The ionic conduction in PMEO complexes under high‐pressure CO₂ was scarcely related to the VTF parameters and activation volume equations. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3151–3158, 2005     

Revision of the volumetric method for measurements of liquid–liquid equilibria in binary systems

A theoretical analysis of the accuracy of the volumetric method for the determination of liquid–liquid equilibrium was carried out. The results show that, under certain conditions, this method can be used to investigate systems showing relatively small mutual solubilities. Relations were derived to estimate standard deviations of the equilibrium compositions determined by the volumetric method.

In the experimental part of the work, an apparatus for measurements of mutual solubilities of liquids was constructed. A procedure that enabled us to determine precisely volumes of liquid phases was developed. This procedure and apparatus present the advantage that relatively small amounts of samples are required (approximately 2 × 20 ml). Theoretical conclusions concerning the applicability of the volumetric method were checked by measuring mutual solubilities at 303.15 K in systems methylcyclohexane + N,N-dimethylformamide, 1-butanol + water and dimethyl phthalate + water. Further, the method was used to measure systematically the liquid–liquid equilibrium in systems ethyl acetate + ethylene glycol and phenyl acetate + ethylene glycol at temperatures from 293 to 323 K. Data for these systems were acquired by means of other methods as well and a good agreement was observed on comparison.     

Geometric properties of semilinear and semibounded sets

We calculate the universal Euler characteristic and universal dimension function on semilinear and semibounded sets and obtain some criteria for definable equivalence of semilinear and semibounded sets in terms of these invariants. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A convergence result for spatially inhomogeneous Preisach operators

Based on the properties of the strongly nonlinear Preisach operator, a convergence result is proved under reasonable assumptions. This work was supported by the project MSM4781305904 of the Czech Ministry of Education     

Microhydration of the magnesium(II) acetate cation in the gas phase

Electrospray ionization of aqueous solutions of magnesium(II) acetate leads to microhydrated magnesium acetate cations of the type [(CH(3)COO)(2m-1)Mg(m)(H(2)O)(n)](+) with m = 1-4 and n = 0-4, which are characterized by mass spectrometry and, for the cluster with three water molecules, also by infrared multiphoton dissociation spectroscopy. Density functional theory is used to determine the energies of microhydration for the mononuclear species [(CH(3)COO)Mg(H(2)O)(n)](+) with n = 0-6 and the associated changes in molecular structure. While bidentate coordination of the acetato ligand is generally preferred, at higher values of n, a switch to a monodentate coordination becomes energetically competitive.     

Characteristics of the energy bands and the spectroscopic parameters of Pr3+ ions in PrCl3 mixed methanol, iso-propanol and butanol solutions

An investigation on the absorption spectra of the praseodymium chloride (PrCl(3)) in methanol, iso-propanol and butanol is carried out between 190 nm and 1100 nm. We have observed and assigned six energy bands of the 4f(2) electronic configuration of the Pr(3+) ion in the visible to near-infra-red and one due to 4f5d configuration in the ultraviolet region. The 4f5d band has been detected properly for low concentration of PrCl(3). We have also constructed a free-ion Hamiltonian and calculated the energy levels of the 4f(2) configuration theoretically. Hence, the best fit free-ion parameters are deduced.     

Allotropic transformation of Se<Subscript>8</Subscript> to Se<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>

Single crystals of cycloocta-Se, unambiguously characterized by XRD were prepared and used in a study of its allotropic transformation to polycatena-Se by DSC supported by Raman spectroscopy and optical microscopy. It was found that the transformation of a Se₈ single crystal to polycrystalline Se _n proceeds progressively within the volume of the monoclinic single crystal without shape change. All the results of DSC, Raman spectroscopy, and optical microscopy indicate that previous proposals on cycloocta-Se melting during transformation are not realistic.