Stabilization of silver clusters by matrices of various chemical nature

Silver clusters having unusual optical and chemical properties and characterized by a band at 320–330 nm, are shown to be stabilized by solid matrices of various chemical nature.

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Ferromagnetic resonance and bistability field in a uniaxial magnetic film

Peculiarities of ferromagnetic resonance (FMR) corresponding to bias along the “hard” magnetic axis of a film with 2D uniaxial anisotropy are studied based on numerical solution of magnetic moment dynamics equations. It is shown that an additional resonance peak is formed in the FMR spectrum in the vicinity of “bistability field” H _b . The dependence of this field on the amplitude of the microwave field and damping parameters is analyzed.     

Spin-wave resonance in a tangentially magnetized thin film

The imaginary part of the magnetic susceptibility determining the position, amplitude, and width of damped bulk and surface spin-wave eigenmodes in the spin system of a thin film magnetized in the film plane along the uniaxial bulk and surface anisotropy axis is analyzed numerically for various values of the degree of surface spin pinning. The presence of damping and the finiteness and asymmetry of the degree of surface spin pinning are shown to cause significant changes in the spin-wave resonance spectrum.     

Structural analysis of composite metal-insulator materials by small-angle x-ray scattering

A small-angle x-ray scattering study of the structure of Cu: SiO₂ composite films obtained by magnetron cosputtering is reported. The experimental spectra are analyzed by direct numerical simulation of scattering from a polydisperse system of spherical particles with a high volume concentration. The calculated scattering spectra were found to fit well to the experiment if a log-normal particle distribution in size is assumed, and the parameters of this distribution were determined.     

Polymerization of Ferrocene in an Electrodeless High-Frequency Discharge Helium Plasma: II.1 Structure and Crystallization Dynamics of Plasmochemically Polymerized Films

The main frequencies in the IR spectra of ferrocene and plasmochemically polymerized ferrocene films obtained in the plasma of an electrodeless high-frequency discharge in mixtures of helium and ferrocene are the same. The appearance in the IR spectra of the films of weak bands is associated with partial decomposition of ferrocene molecules in the high-frequency discharge plasma.     

Segmentation of Heteropolymer Sequences Specifying Subsequences with Different Composition and Statistical Properties

We have studied the segmentation of two‐letter AB heterosequences composed of subsequences with different composition and distribution of A and B monomer units along the chain. Our approach is based on the segmentation function S(k) introduced in the present work and on the Jensen–Shannon divergence measure determined with respect to the probabilities of the lengths of uniform blocks of A and B monomer units. It is shown that the function S(k) is extremely sensitive to the sequence statistics. Even visual analysis of S(k) allows judgment on some features of sequence statistics. In particular, function S(k) is constant for random copolymers, it is an oscillating function for random block copolymers and shows monotonic growth up to some constant value for proteinlike copolymers. However, due to significant fluctuations observed for short sequences, the function S(k) can be effectively used only for segmentation of a heterosequence composed of very long subsequences. On the other hand, we find that the Jensen–Shannon divergence measure does not allow one to judge the type of statistics, but is extremely efficient for segmentation of a heterosequence. Therefore, the two introduced functions, being mutually complementary, provide an effective approach for recognizing and segmentation of heterosequences. As an example, the methods developed are applied for concatenating sequences of different proteins.

Segmentation function S(k, l, x) as a function of parameter k and starting number x of “window” for a sequence composed of elastin and ribonuclease sequences.     

Salt effects on macrophase separations in non‐stoichiometric mixtures of oppositely charged macromolecules: Theory and experiment

In the field of biological applications, polyelectrolyte complexes are proposed to encapsulate bioactive compounds, to deliver drugs, and also to transfect genes into cells under the name of polyplexes. Complex formation is obtained by addition of a polycation solution into a polyanion solution or vice‐versa. This work proposes a theoretical approach to describe complex formation in the case of non‐stoichiometric mixtures of oppositely charged macroions having different degrees of ionization and different degrees of polymerization under different salt conditions. In a second part, comparison was made with experimental data collected when a weak polybase, namely poly(l ‐lysine) under its bromide form was added stepwise to solutions of various polyanions under their sodium salt form, namely poly(l ‐lysine citramide imide), poly(l ‐lysine citramide), and poly(β‐malic acid), the latter lacking hydroxyl groups attached to the main chain. The stability of stroichiometric complexes made of poly(l ‐lysine) and poly(l ‐lysine citramide) having different molecular masses is discussed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1717–1730     

Spectral manifestation of the interaction of polyurethane components with oxide groups

The spectral-structural characteristics of polyurethane compositions with antipyrene fillers were investigated by a method of IR spectroscopy. The changes revealed in the vibrational spectra can be caused by intermolecular interaction of oligoether and diphenylmethane diisocyanate with aluminum-, boron-, and phosphor-containing compounds.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 1, pp. 133–135, January–February, 2005.     

The structure of fullerene films and their metallocene doping

Hexagonal close-packed (HCP) C₆₀ and C₇₀ films have been prepared by the Langmuir method and examined by electron microscopy and electron-diffraction analysis. It has been shown that the vacuum deposition of a C₆₀+C₇₀ mixture results in the formation of a film with small sized grains and a distorted C₆₀-HCP structure. The simultaneous deposition of C₆₀ and ferrocene results in the formation of a film with a changed morphology and an electron-diffraction pattern that contains a variable amount of ferrocene depending on the experimental conditions. The electron-diffraction pattern corresponds to the presence of the known molecular complex C₆₀[(C₅H₅)₂Fe]₂. The analogous simultaneous deposition of fullerene C₆₀ and cobaltocene results in the formation of a C₆₀ film stable in air and water, which contains carbon and cobalt (from the data of X-ray fluorescence, electron microscopy and microdiffraction). It has a different morphology and different diffraction patterns than pure C₆₀ films and, depending on the cobaltocene content (relative to that of fullerene), appears to be a fullerite film doped with various amounts of cobaltocenium fullende, which is an ionic compound.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1379–1383, August, 1994.The work was financially supported by the Russian Foundation for Basic Research (Projects 93-03-4676 and 93-03-18368).     

A Convenient Method of N-Methylphthalimide Synthesis

We suggest a convenient method to obtain N-methyiphthalimide with a high yield in the reaction of phthalic anhydride with aqueous methylamine.