Label‐Free Electrochemical Thrombin Aptasensor Based on Ag Nanoparticles Modified Electrode

A novel label‐free electrochemical method for protein detection based on redox properties of silver was developed. As recognition elements, thrombin‐binding aptamers were used. Screen printed electrodes modified with silver nanoparticles (AgNP) were employed as a sensing platform for aptasensor devices. The oxidation of silver upon polarization served as a basis for analytical response. Three different thrombin binding aptamers with various surface concentrations were studied. Linear range of aptasensor response corresponded to the 10⁻⁹ M to 10⁻⁷ M thrombin concentration range and the detection limit was 10⁻⁹ M.     

Direct Electrochemistry of Heme Proteins on Electrodes Modified with Didodecyldimethyl Ammonium Bromide and Carbon Black

A novel matrix based on commercially available carbon black (CB) N220 and didodecyldimethyl ammonium bromide (DDAB) was shown to be a reliable support for direct electron transfer reactions between screen printed electrode (SPE) and Fe(III)‐heme proteins. Cytochrome c (cyt c), myoglobin (Mb), horseradish peroxidase (HRP) and cytochromes P450 (CYP 51A1, CYP 3A4, CYP 2B4) generated well‐shaped cyclic voltammograms on SPE/CB/DDAB electrodes (both in solution and in immobilized state). The attractive performance characteristics of CB modified electrodes are advantageous over single‐walled carbon nanotubes (SW CNT) based ones. The achieved direct electrochemistry of heme proteins on CB/DDAB‐modified electrodes provided successful elaboration of the immunosensor for cardiac Mb. The immunosensor showed applicability for diagnostics of myocardial infarction displaying significant difference in cardiac Mb content of human blood plasma samples taken from the corresponding patients.     

Interpolation with Specified Error of a Point Series Belonging to a Monotone Curve

The paper addresses the problem of modeling a smooth contour interpolating a point series belonging to a curve containing no special points, which represents the original curve with specified accuracy. The contour is formed within the area of possible location of the parts of the interpolated curve along which the curvature values are monotonously increased or decreased. The absolute interpolation error of the point series is estimated by the width of the area of possible location of the curve. As a result of assigning each intermediate point, the location of two new sections of the curve that lie within the area of the corresponding output section is obtained. When the interpolation error becomes less than the given value, the area of location of the curve is considered to be formed, and the resulting point series is interpolated by a contour that lies within the area. The possibility to shape the contours with arcs of circles specified by characteristics is investigated.     

Point-defect interaction in a dislocation core

By minimizing the thermodynamic potential we derive formulas for equlibrium length-distributions of dislocation segments and one-dimensional clusters formed from point defects in a dislocation core. The theoretical formulas are compared with results of computer modeling. Temporal variations of cluster-formation processes are discussed. Plots of the number of clusters and average and maximum lengths of clusters and dislocation segments as functions of time are presented. Moscow Technological University of Steel and Alloys. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 74–81, April 2000.     

Representation of a Monotone Curve by a Contour with Regular Change in Curvature

The problem of modelling a smooth contour with a regular change in curvature representing a monotone curve with specified accuracy is solved in this article. The contour was formed within the area of the possible location of a convex curve, which can interpolate a point series. The assumption that if a sequence of points can be interpolated by a monotone curve, then the reference curve on which these points have been assigned is monotone, provides the opportunity to implement the proposed approach to estimate the interpolation error of a point series of arbitrary configuration. The proposed methods for forming a convex regular contour by arcs of ellipses and B-spline ensure the interpolation of any point series in parts that can be interpolated by a monotone curve. At the same time, the deflection of the contour from the boundaries of the area of the possible location of the monotone curve can be controlled. The possibilities of the developed methods are tested while solving problems of the interpolation of a point series belonging to monotone curves. The problems are solved in the CAD system of SolidWorks with the use of software application created based on the methods developed in the research work.     

Methods for Concentration of Hydrogen Peroxide To Obtain It in Anhydrous Form

Methods for concentrating hydrogen peroxide and obtaining this compound in anhydrous form, based on removal or binding of water from the surface of solution in an open vessel or in a closed volume and also on binding of water directly in a H₂O₂ solution, are described.