Influence of the atomic weight of the target on the magnitude of the energy accommodation coefficient of ions of a partially ionized gas flow

One of the most essential parameters in the investigation of singularities in molecule interaction with the surface of a solid is the energy accommodation coefficient. Data on the positive ion accommodation coefficients in the energy range 1–100 eV are scarce [1], hence the value of _i is often taken close to one, although this condition is not satisfied in practice for the majority of working gases. In this paper we discuss the resultant measurements of the value of _i in a high-speed flow of rarified plasma.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 83–87, May–June, 1979.     

General formalism for plane guided waves in transversely inhomogeneous anisotropic plates

The sextic approach to plane waves in infinite (visco)elastic plates of arbitrary anisotropy and transverse inhomogeneity is outlined. A particular thrust is set on continuous inhomogeneity when the propagator is defined by the Peano expansion. Despite underlying explicit intricacy, the basic framework of the pursued formalism is little affected by a through-plate variation of material. To make it evident, the principal algebraic symmetry of the propagator for unattenuated waves and the ensuing arrangement of the impedance as a Hermitian matrix with specific traits are inferred directly from energy considerations. Staying the same as for homogeneous plates, those features yield useful developments in the broader context of inhomogeneity. The formalism may be expressed in either pair picked among velocity, frequency and wavenumber, but different choices of a dispersion variable are shown to entail analytical dissimilarities. In addition, the impact of the profile symmetry and of the horizontal plane of crystallographic symmetry is examined. The surface-impedance method and some other aspects of the numerical treatment are discussed.     

The Stroh formalism and the reciprocity properties of reflection-transmission problems in crystal piezo-acoustics

The paper is concerned with the Helmholtz-Rayleigh reciprocity, which implies invariance of mode-into-mode transformation with respect to interchange of incident mode and reflected or transmitted mode. This concept is considered for a wide range of acoustic reflection-transmission problems in anisotropic piezoelectric media. Resorting to the ideas of the Stroh formalism and casting the wave solutions of a boundary problem into a self-orthogonal and complete set, we develop the common approach which allows us to prove the reciprocity properties in a similar fashion for reflection-transmission for various boundary conditions.     

Impact of localized inhomogeneity on the surface-wave velocity and bulk-wave reflection in solids

The effect of a weak surface, near-surface and interfacial inhomogeneity on the frequency dependence of the surface wave velocity and of the SH (shear horizontal) wave reflectivity in isotropic elastic media is studied analytically and numerically. The inhomogeneity is modeled as an infinite planar layer with continuously varying properties. Weak inhomogeneity may markedly affect the dispersion of the Rayleigh velocity and especially of the reflectivity. It is demonstrated how this effect, particularly pronounced at high frequency, depends on the extent of inhomogeneity. The material data for damaged and ideal concrete and several simple examples of inhomogeneity profiles are utilized for the numerical calculations based on the Peano expansion. The use of explicit low- and high-frequency approximations is also exemplified. Among these, simple WKB asymptotics are shown to be particularly helpful for the Rayleigh velocity in the case of a prominent inhomogeneity attached to the surface and for the reflection on weak interfaces.     

Orientational contribution to the piezoelectric constants of BaTiO3 ceramic in ferroelectric phases with various symmetries

A self-consistent method based on the interaction of a piezoelectric sphere with a piezoelectric medium that has anisotropic elastic and dielectric properties is used to calculate the components of the tensor piezoelectric modulus of BaTiO₃ ceramic in all three ferroelectric modifications. A comparison of the calculated and measured piezoelectric moduli shows that at least 60–70% of the piezoelectric effect in BaTiO₃ ceramic is caused by domain boundary movement throughout the entire ferroelectric region. Fiz. Tverd. Tela (St. Petersburg) 41, 1080–1083 (June 1999)     

Synthesis and photophysical properties of the products of the reaction of 5-methyl-7-phenyl[1,3]oxazolo[5,4-b]pyridin-2(1H)-one with amino acids

Chemistry of Heterocyclic Compounds - The reaction of amino acid esters with 7-phenyl[1,3]oxazolo[5,4-b]pyridin-2(1H)-one led to the derivatives of...     

Naphthoquinone-derived polyol macrolides from natural sources

Russian Chemical Bulletin - New biologically active substances isolated from natural sources provide valuable information on structural motifs that are important for a specific type of activity and...     

New approach to the synthesis of 2,2':5',2'-terthiophene-5,5'-and 2,2':5',2':5',2''-quaterthiophene-5,5''-dicarboxylic acids

Chemistry of Heterocyclic Compounds - The reaction of bromosuccinimide with esters of 3-substituted 2,2'-bithiophene-5-carboxylic acids was used to obtain their 5'-bromo derivatives, which...     

On the motion of a heavy body with a circular base on a horizontal plane and riddles of curling

In this paper we discuss the dynamics of an axisymmetric rigid body whose circular area moves upon a horizontal rough surface. We investigate the interaction between the character of the law of friction and the curvature of the body’s trajectory. For the case of a curling stone it is shown that the observed effects can only be explained using the dependence of the friction coefficient on the Gümbel number. The procedure for constructing the law of friction based on experimental data is developed. It is shown that the available data can only be substantiated by means of anisotropic friction. The simplest model of such friction is constructed which provides quantitative coincidence with the experiment.     

Comments on “An analytical study of sound transmission through unbounded panels of functionally graded materials. Journal of Sound and Vibration 330(6) (2011)1153-1165”

The vector function in Eq. (28) which is presented as the solution of a system of ordinary differential equations is incorrect.