E. V. Ignat’eva

Pseudocavitation during low-frequency treatment of melts

Low-frequency and ultrasonic treatments of a melt are compared theoretically. The phenomenon caused by low-frequency treatment of a melt and called pseudocavitation is considered. The conditions of the appearance of this phenomenon are revealed, and an experiment on mixing of a “light” aluminum powder with “heavy” Wood’s alloy is performed under pseudocavitation conditions.

Principal distinction of the methods of low-frequency and ultrasonic effects on melts

Factors that determine the difference between low-frequency and ultrasonic treatments methods are discussed: cavitation phenomena, dissipative losses, and the possibility for the turbulent mixing of the melts. The independence of each method is proven.

Search for new binding sites for the transcriptional factor SF-1 by the SITECON method: Experimental verification and analysis of regulatory regions of orthologous genes

165 Recognition of transcriptional factor binding sites in genomic sequences is a promising approach to deciphering the regulatory code of DNA. Today, the methods of recognition of transcriptional factor binding sites based of various principles (consensus, weight matrices, etc.) are known and widely used [1]. However, in most cases, the recognition accuracy of transcriptional factor binding sites is insufficient for analysis of extended genomic sequences [2, 3], which makes it necessary to use additional criteria that allow the percent of false predictions to be decreased [3–5]. In addition, in different situations, the existing methods of recognition of transcriptional factor binding sites may differ significantly with respect to recognition quality even within the same approach (e.g., weight matrixes) [6]. For this reason, development of new approaches to recognizing transcriptional factor binding sites remains a topical problem. Another key problem is determination whether the transcriptional factor binding sites predicted by computer methods are functional in the regulatory regions of different genes in vivo (i.e., in chromosomes in living cells).

Combined Low-Frequency and Electro-Impulse Treatment of Molten Metal

A method is given for preparing alloy using combined low-frequency and electro-impulse action on a melt. Metallographic comparison is provided for the result of using this procedure with results of preparing alloy with separate low-frequency and electro-impulse methods on the example of alloy of the Al–Ti–C system. It is established that melt treatment by the new method leads to a variety of aluminide growth shapes.

Imparting Ductility to a Steel–Aluminum Composite Laminate in Forming Operations

One of the major disadvantages of corrosion-inhibiting aluminum coatings on steel is the presence of a brittle intermetallide layer between the steel substrate and aluminum coating. This paper reports results from an investigation of the problem. A manufacturing scheme based on the treatment of such laminated composites by forming operations is proposed.

On the “elasticity” of waves during vibrating action on a melt

The problem of the elasticity of the ultrasonic and low-frequency waves generated in a metallurgical melt by a vibrating piston is theoretically considered on the basis of acoustic equations and experimental data. The modes of vibration treatment of melts where a wave can or cannot be considered as elastic have been determined.

Steel-aluminum layered composite with a nanostructured intermediate layer

The results of an investigation into the influence of the degree of deformation on the structure of components of the layered steel-aluminum composite are presented. It is shown that the noticeable structural variations start from reduction ratio ɛ > 75%, or e > 1.54 in logarithmic units. The plastic deformation mechanism of a brittle intermetallic layer is described. It is shown that the viscoplastic intermediate layer of the steel-aluminum layered composite can be obtained by rolling when bringing the deformation ratio to 90%. As for the submicron structure, it can be obtained at ɛ > 95%, or e > 3.

Features of the low-frequency treatment of melts

A method for obtaining cast composites using the effect of low frequencies on the melt is presented. Some features of the process and the results of vibrational treatment are unobvious and require theoretical explanation. The factors that prevent the introduction of the powders into the melt volume and the factors affecting the variation in the sizes of the structural components of the melt during low-frequency melting are considered. A new interpretation of the crushing and coagulation mechanism during low-frequency treatment (LFT) with a mathematical description and experimental confirmation is proposed.

Analysis of the refinement and coalescence of solid particles during low-frequency treatment of metal melts

The refinement and subsequent coalescence of powder particles and the related aluminides forming during low-frequency treatment of aluminum composite melts are studied. The milling of the initial particles to the limiting size of several micrometers and their subsequent association into conglomerates and a mathematical description of these processes are presented in terms of a new approach.

Conglomeration of metallic power and destruction of conglomerates

Theoretical principles describing the formation and disintegration of conglomerates are developed and used to formulate a method for mixing nanodisperse, ultradisperse, and highly disperse powders, with simultaneous disintegration of conglomerates. The operation of the corresponding mixing equipment is described.