(Y0.5Lu0.5)2O3:Eu3+ nanopowders: Combustion synthesis,structure and optical properties

In this work we explored the possibility of obtaining nanocrystalline (Y_0.5Lu_0.5)₂O₃ powders, doped with europium and co-doped with praseodium, employing polymer complex solution synthesis. Polyethylene glycol, with average molecular weight 200, served both as a fuel and dispersing medium for nanocrystals formation. We investigated structure, morphology, luminescence emission and decay characteristics of obtained powders and how different concentrations of Pr co-dopant affect theirs optical characteristics.     

Recognition of the carbon thin films sub-structures: thermo-optical measurements

Carbon thin films oxidation was investigated on-line by high-sensitivity optical transmission (OT) method. The films have been prepared by common vacuum arc discharge and subsequently air oxidized at linear heating rates until temperatures of their complete gasification. The shape of the optical curves acquired was interpreted in light of deduced partial optical changes, each of them being ascribed by simple sigmoidal dependence. The dependencies converted to their derivative form ordered respective to the temperature scale conveniently represent an inter-relationship among the sequentially evolved films’ optical events, considered as being closely related to the individual carbon-replenishing steps. The dependencies correspond well to the ones obtained on thicker films by means of the thermogravimetry (TG) measurements.     

On the Underlying Lower Order Bundle Functors

For every bundle functor we introduce the concept of subordinated functor. Then we describe subordinated functors for fiber product preserving functors defined on the category of fibered manifolds with m-dimensional bases and fibered manifold morphisms with local diffeomorphisms as base maps. In this case we also introduce the concept of the underlying functor. We show that there is an affine structure on fiber product preserving functors. Tis work was supported by a grant of the GA CR No. 201/02/0225.     

Mössbauer Spectrometer with Novel Moving System and Resonant Detection of Gamma Rays

Temperature-dependent ⁵⁷Fe Mössbauer spectroscopy has been used to elucidate the hyperfine parameters and dynamical behavior of the metal atom in several organo-iron complexes which have one or more η⁵ P₅ ring structures as ligated groups. The spin-lattice relaxation of the (paramagnetic) one-electron oxidation products occurs on a time scale fast compared to τ_1/2 (ME) at temperatures in the range 85 < T < 320 K.     

Identities over the two-element alphabet

In [4] and [5] the authors considered semigroup identities that induce various types of decompositions. In this paper we continue this work for identites over the two-element alphabet. In particular, we solve some problems that are not solved in the general case and we solve several types of well known Tamura's problems. Supported by Grant 0401A of RFNS through Math. Inst. SANU.     

Hankel and Loewner matrices

Mutual relations between the Hankel, Toeplitz, Bézout, and Loewner matrices as well as further connections to rational interpolation and projective geometry are investigated.     

Contributions to the Gaussian Line Broadening of the Proxyl Spin Probe EPR Spectrum Due to Magnetic-Field Modulation and Unresolved Proton Hyperfine Structure

A simple expression is derived to compute the total Gaussian linewidth of a Voigt line that is broadened by sinusoidal magnetic-field modulation as follows: ΔH^G_pp(H_m)²= ΔH^G_pp(0)²+ κ²H²_m, where ΔH^G_pp(H_m) is the Gaussian linewidth observed with an modulation amplitudeH_m/2 and ΔH^G_pp(0) is the Gaussian linewidth in the limit of zero modulation. The field modulation contributes an additional Gaussian broadening of κH_m, where κ is a constant, which adds in quadrature to ΔH^G_pp(0) to give the total Gaussian linewidth. Denoting the overall linewidth of the Voigt line in the absence of modulation broadening by ΔH⁰_pp(0), it is shown, both by analytical means and by spectral simulation, that the constant κ is equal to 1/2 in the limit ofH_m ΔH⁰_pp(0); however, using values ofH_mas large as ΔH⁰_pp(0) leads to only minor departures from κ = 1/2. The formulation is valid both for Lorentzian and Voigt lines and is tested for 2,2,5,5-tetramethylpyrrolidin-1-oxyl-3-carboxylic acid (3-carboxy proxyl) in CCl₄and in aqueous buffer. This spin probe was studied because the proxyl group is the only major spin-probe moiety whose Gaussian linewidth had not been characterized in the literature. For 3-carboxy proxyl, it is found that ΔH^G_pp(0) = 1.04 ± 0.01 G independent of solvent polarity. Precision values of the¹⁴N hyperfine coupling constant for 3-carboxy proxyl at 9.5°C are as follows: 14.128 ± 0.001 G in CCl₄and 16.230 ± 0.002 G in aqueous buffer. The temperature dependence of ΔH^G_pp(0) and the¹⁴N hyperfine coupling constant are reported as empirical equations. Results of the present work taken together with previously published data permits accurate correction for the effects of inhomogeneous broadening due to unresolved hyperfine structure and modulation broadening for the majority of spin probes in common use.     

On the general form of the Beltrami equation and Papkovich's solution of the axially symmetrical problem of the classical theory of elasticity

The paper shows the connection between the general form of the Beltrami equation of compatibility, which had already been derived by the author, and the form given for it in orthogonal curvilinear coordinates by Lurye (para 2, 3).Some of the properties of Papkovich's general solution of the axially symmetrical problem (without body forces) of the theory of elasticity and its relation to the Finzi-Krutkov solution are discussed so as to supplement to a certain extent the paper of Trenin (para 4, 5, 6).