Dynamical Dzyaloshinsky-Moriya interaction in KCuF3

The spin dynamics of the prototypical quasi-one-dimensional antiferromagnetic Heisenberg spin S=1/2 chain KCuF3 is investigated by electron spin resonance spectroscopy. Our analysis shows that the peculiarities of the spin dynamics require a new dynamical form of the antisymmetric anisotropic spin-spin interaction. This dynamical Dzyaloshinsky-Moriya interaction is related to strong oscillations of the bridging fluorine ions perpendicular to the crystallographic c axis. This new mechanism allows us to resolve consistently the controversies in observation of the magnetic and structural properties of this orbitally ordered perovskite compound.     

Broadband emission of dye mixtures in films and polymer matrices

Emission of mixtures of organic compounds in thin acrylic films and matrices is investigated from the blue to red range of the spectrum. The present paper is aimed at studying the feasibility of obtaining white light by conversion of output diode radiation (379 nm) using a mixture of fluorophors. It is demonstrated that the emission band shape depends on ratios of dye concentrations and geometry of excitation and registration that must be taken into account in the development of devices based on these compounds.__________This revised version was published online in May 2005 with a correction on affiliation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 67–70, November, 2004.     

Activated Carbons from Waste Wood in Wastewater Treatment To Remove Surfactants

Activated carbons synthesized by steam-gas treatment of charcoal produced from wastes formed in cutting of mixed wood were tested in adsorption of surfactants from aqueous solutions: anionic (Volgonat, Uglepen, neutralized black catalyst) and cationic (Katamin AB). Isotherms of adsorption of these impurities are presented, and a flowsheet of step-by-step wastewater treatment to remove surfactants by adsorption is suggested.     

New Lead Orthosilicate {Pb4(О(ОН)2)}[SiO4] with a Framework of Anion-Centered Pb Tetrahedra Related to Sodalite

Crystallography Reports - New lead silicate {Pb4(О(ОН)2)}[SiO4] was synthesized under hydrothermal conditions and structurally characterized, sp. gr. P213, а = 8.9756(13)...     

Simulations of light scattering spectra of a nanoshell on plane interface based on the discrete sources method

The resonance properties of nanoshells are of great interest in nanosensing applications such as surface enhanced Raman scattering or biological sensing. In this paper the discrete sources method has been applied to analyze the spectrum of evanescent light scattering from a nanoshell particle deposited near a plane surface. Based on the rigorous theoretical model, which allows to take into account all features of the scattering problem as: medium with frequency dispersion, presence of the interface, the objective aperture and its location and core-shell asphericity, the scattering spectrum of nanoshells was calculated. The dependence of the local nanoshell spectral density behavior on its properties is discussed.     

EPR spectra of a GdMnO3 thin film on a SrTiO3 substrate

Electron paramagnetic resonance (EPR) spectra of a GdMnO₃/SrTiO₃ thin film in the X band have been measured in the temperature interval from 200 to 450 K. Signals from two types of paramagnetic centers have been observed in the spectra. The first paramagnetic center is a subsystem of Gd³⁺ ions, in the EPR spectrum of which the fine structure lines are resolved below 350 K. The second paramagnetic center is a system of manganese and gadolinium ions, in the EPR spectrum of which an exchange-narrowed line is observed with the width ΔH several times less than the width ΔH of an exchange-narrowed line observed in the GdMnO₃ single crystal. Unusual magnetic properties are due to the mismatch of the lattice parameters of the GdMnO₃ thin film and the SrTiO₃ substrate.     

The structural-phase state of C<Subscript>60</Subscript>-C<Subscript>70</Subscript> fullerene mixtures

The structural and phase state of the C₆₀-C₇₀ system at various C₆₀/C₇₀ ratios in mixtures obtained by the vaporization of solutions in toluene at ∼98°C was studied by X-ray structure analysis, differential scanning calorimetry, and infrared spectroscopy. Solid solutions based on the face-centered cubic packing of C₆₀ are not formed in the C₆₀-C₇₀ system at C₇₀ contents from 0.5 to 50 wt %. The hexagonal close packing of a solid solution of C₆₀ in C₇₀ can be formed as a result of the thermally activated decomposition of the ternary crystal solvate in the C₆₀-C₇₀-C₆H₅CH₃ system. The structural state of multiphase mixtures formed under conditions far from equilibrium is characterized by a high degree of structure imperfection and greater ability to undergo oxidation compared with C₆₀ and C₇₀.     

Light scattering by an erythrocyte based on discrete sources method: Shape and refractive index influence

An efficient method for the fast detection of properties of a single erythrocyte from its scattering characteristics is needed in practice. To develop such a method a detailed investigation of the light scattering properties of the erythrocyte and their dependence on its shape and refractive index is of great interest. In this paper the influence of the real erythrocyte's shape with deep concavities and refractive index on the scattering characteristics is analyzed based on an updated scheme of the discrete sources method. Realistic shape models of an erythrocyte, calculated from minima of membrane potential energy are considered. The numerical scheme of discrete sources method has been adjusted for shape profiles given numerically. An improved algorithm allows increasing of an accuracy of calculations.     

Calculating the nominal yield point of structurally heterogeneous powders

Perm. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 1, pp. 134–138, January–February, 1995.