V. S. Plotnikov

Graphics processors in problems of electron tomography

Algorithms were developed for the tomographic reconstruction of structure from microscopic images using graphics processors of general application. The effect of noise and the choice of reconstruction filters for tomographic problems in materials science is investigated. It is shown that the use of ρ-filtration in reconstruction allows one to estimate the geometrical characteristics of three-dimensional microstructures in amorphous metal alloys.

Methods of Analysis of the Structure of Materials on the Basis of Orthogonal Transformations of Microscopic Images

Some methods for studying the structure of materials on the basis of microscopic images are considered. The images are analyzed using various orthogonal transformations: Fourier, cosine, Hartley, and continuous wavelet transformations.

Investigation of DNA-damage and Chromosomal Aberrations in Blood Cells under the Influence of New Silver-based Antiviral Complex.

PURPOSE The problem of infectious diseases and drug resistance is becoming increasingly important worldwide. Silver is extensively used as an anti-infective agent, but it has significant toxic side effects. In this regard, it is topical to develop new silver compounds with high biological activity and low toxicity. This work is aimed to study DNA damage and chromosomal aberrations in blood cells under the influence of new silver-based compound of general formula C6H19Ag2N4LiO6S2, with antiviral activity. METHODS The comet assay was applied for the genotoxic affects assessment on mice blood leukocytes. DNA damage was determined bases on the percentage of DNA in a comet tail (tail DNA), under the influence of silver complex in different concentrations. Genotoxic effect of the tested substance on the somatic cells was determined by chromosomal aberration test of bone marrow cells of mice. RESULTS In the course of the experiments, no essential changes in the level of DNA damage in the cells were found, even at highest concentrations. The administration of the substance in doses up to 2.5 g/kg in mice did not cause any increase in the frequency of chromosomal aberration in bone marrow cells. CONCLUSION Taking into account known silver drug genotoxic properties, the use of a given complexed silver compound has possible great advantages for potential applications in the treatment of infectious diseases.

Structure Evolution of Fe- and Co-Based Amorphous Alloys Studied by the Electrical Resistivity Measurements

The subject of this study is the change of the electrical resistivity of Fe-based metallic glasses during heat treatment. Electrical resistivity is a structure-sensitive characteristic of materials. In metallic glasses, the scattering of conduction electrons on the disordered structure is the main mechanism responsible for the electrical resistivity. Hence amorphous metallic alloys have a much higher residual resistivity as compared to their crystalline analogs. It is typical for metallic glasses that the temperature coefficient of resistivity (TRC) is smaller than for the corresponding crystalline materials, and it can be either positive or negative.

HAADF-STEM investigation of the structures of electrolytically deposited CoP and CoNiP alloys

The structure and chemical composition of electrolytically deposited films of CoP and CoNiP amorphous alloys are studied by means of high-angle annular dark-field scanning transmission electron microscopy in the z-contrast mode, and via EELS and EDS spectroscopy with high locality. It is shown that variations in chemical composition correlate with heterogeneities in film structure.

Electron tomography and STEM investigations of the structure of multilayer amorphous and nanocrystalline alloys of CoP-CoNiP, CoW-CoNiW systems under external action

The structure of amorphous and nanocrystalline alloys of the CoP-CoNiP and CoW-CoNiW systems under the external action is investigated by means of high-resolution transmission electron microscopy and electron tomography. It is revealed that the crystalline phase is predominantly nucleated in the regions with the maximum density gradient. Algorithms for image filtering and reconstruction for a graphical processor unit are implemented.

Investigating the structure of electrolytically deposited alloys of the CoP-CoNiP system under thermal action

The problems of structural relaxation and crystallization of electrolytically deposited amorphous metal alloys of the CoP-CoNiP system are investigated. The onset of the structural relaxation and crystallization is found to occur through the nucleation of nanocrystalline particles of an unrecognized CoxNiyP1−x−y phase. An increase in the concentration of Ni is shown to yield a substantial thickening of the amorphous structure and to increase the temperature of the onset of structural relaxation and crystallization by 50–70°C.

Effect of composition on the structural relaxation of amorphous iron-based alloys

The structural relaxation of iron-based amorphous alloys upon changes in their relative electrical resistance and magnetic moments upon a rise in temperature is investigated. The presence of Nb in Fe(Cu, Nb)–Si,B alloys stabilizes amorphous states, lowering the Curie temperature TCam and raising the temperature of the paramagnetic–ferromagnetic magnetic phase transition.

Electron tomography as a tool for studying the structures of amorphous alloys

Structural defects in amorphous and nanocrystalline alloys of the CoP–CoNiP–NiP and CoW‒CoNiW–NiW systems are studied by means of electron tomography. An algorithm and software are developed to optimize the level of binarization of tomographic models used to select objects. Computer simulations show that the distribution of the volume of material density fluctuations is a Pareto distribution. It is established that a modified Pareto distribution describes the experimental distribution of volumes with a smaller error.

Surface irregularities and magnetism in amorphous metal foils on Fe basis

This paper presents the study results of morphology contact and free surface at amorphous metal foils (Fe7Co71Ni12(SiB)10, Fe70Ni10(SiB)10, Fe60Co30(SiB)10) and their analysis of the elemental composition. Using spectral methods of research was allowed to make a comparative analysis size and anisotropy of distribution topological inhomogeneities. A parallel study of spinning foils by Mossbauer spectroscopy and Vibrating sample magnetometer (VSM) possible to determine the magnetic state of the samples.