Features of plane wave propagation along the layers of a prestrained nanocomposite

Features of the propagation of longitudinal and transverse plane waves along the layers of nanocomposites with process-induced initial stresses are studied. The composite has a periodic structure: it is made by repeating two highly dissimilar layers. The layers exhibit nonlinear elastic behavior in the range of loads under consideration. A Murnaghan-type elastic potential dependent on the three invariants of the strain tensor is used to describe the mechanical behavior of the composite constituents. To simulate the propagation of waves, finite-strain theory is used for developing a problem statement within the framework of the three-dimensional linearized theory of elasticity assuming finite initial strains. The dependence of the relative velocities of longitudinal and transverse waves on two components of small initial stresses in each layer and on the volume fraction of the constituents is studied. It is established that there are thickness ratios of layers in some nanocomposites such that the wave velocities are independent of the initial stresses and equal to the respective wave velocities in composites without initial stresses __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 4, pp. 3–26, April 2007.     

Fracture of cylindrical shells with cracks in tension

In practice, cracks may frequently be introduced in structural components during the course of the technological manufacturing and service. Studies concerning the strength prediction of structures with cracks are therefore of considerable importance. During the fracture process of thin-walled structure elements, material local to the crack may buckle. The fracture characteristics may be affected considerably. Both theoretical and experimental studies of this problem were made for plates [1]. In this work, experimental results are presented for the deformation and fracture of cylindrical shells with cracks.     

Theoretical description of a delamination mechanism in fibrous micro- and nanocomposites

Theoretical analysis and numerical modeling of unidirectional fibrous micro- and nanocomposites carried out based on the theory of two-component mixture testify that the second mode of a transverse wave propagating along and polarized across the fibers may produce, at high frequencies, a kinematical pattern critical for the strength of the composite material. While the wave propagates, the components (matrix and fibers) of the mixture oscillate in antiphase. This fact may be critical because such oscillations generate forces separating the matrix and fibers, which is typical for the delamination of composite materials.Translated from Prikladnaya Mekhanika, Vol. 40, No. 10, pp. 78–87, October 2004.     

A new sensitive spectrophotometric determination of sodium 2-mercaptoethanesulfonate using leuco xylene cyanol FF

A simple and accurate spectrophotometric method for determination of sodium 2-mercaptoethanesulfonate (MESNa) with leuco xylene cyanol FF (LXCFF) has been developed. The proposed method is based on the reaction of MESNa with potassium iodate(V) in acidic medium to liberate iodine, which oxidizes leuco xylene cyanol FF to its blue form xylene cyanol FF. The xylene cyanol FF dye formed shows maximum and stable absorbance at pH 4.1–4.2. Absorbance of the obtained colored products was measured at 613 nm. The molar absorptivity, limit of detection and limit of determination of the method were found to be 3.64 × 10⁴ L/mol cm, 0.29 and 0.33 μg/mL, respectively. The colour system obeys Beer’s laws in the range 0.4–4.0 μg/mL of MESNa. All the variables were studied in order to optimize the reaction conditions. The procedure was used for determination of MESNa in pharmaceutical preparations. Reliability of determination was confirmed applying standard iodometric method, recommended by European and Polish Pharmacopoeia.     

Model system for targeted drug release triggered by immune-specific signals

A new sense-and-act system was realized by integrating a biocatalytic/bioaffinity electrode responding to immune signals represented by an antibody and a polymer-modified electrode loaded with drug-mimicking species. The release of the drug-mimicking species was achieved specifically in response to a signal antibody, thus demonstrating for the first time an immune-induced drug-releasing process. The present approach promises new options for future applications in controlled drug release and personalized medicine.

On the problem of evaluation of scientific publications

The paper is concerned with the problem of evaluation of scientific publications as a part of the general problem of scientific information environment. A discussion on objective citation (entitled “Proposal from the Timoshenko Institute” and took place on the Internet in July 2007) is reviewed. New criteria (h-index, g-index) are discussed. A recent discussion by the mathematician community on the evaluation of scientific publications is presented. Some comments and proposals are formulated     

Presentation of the monographs of the S. P. Timoshenko Institute of Mechanics to the scientific community

This paper presents information on 220 monographs published by scientists of the S. P. Timoshenko Institute of Mechanics (National Academy of Sciences of Ukraine) and available in the Library of Congress (USA), and on ways (reading rooms and catalog numbers) of familiarizing oneself with them. The Library of Congress Online Catalog makes it possible to obtain information on these monographs via the Internet at any center of science in any country. This allows the scientific community to access the results presented in these monographs and resolves the problem of presenting them to the world’s scientific community __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 3, pp. 3–49, March 2006.     

A dynamic problem for a prestressed compressible layered half-space

The linearized theory of elasticity for prestressed bodies is used to solve a stationary plane problem for a prestressed two-layer half-space under a surface load moving with constant velocity. The half-space is assumed to be compressible and to have an arbitrary elastic potential. The Fourier transform is used to obtain the fundamental solution of the problem for different contact conditions and load velocities. A compressible material with a harmonic elastic potential is considered as an example __________ Translated from Prikladnaya Mekhanika, Vol. 44, No. 4, pp. 35–55, April 2008.