Effect of electrical circuits on duration of an acoustic pulse radiated by a piezoplate.

By means of numerical computation, pulse mode of a piezoelectric radiator in the form of a plate, loaded with a liquid and connected to R-L circuits in various combinations, is investigated. The computations were carried out having taken into account the internal resistance of the electric generator. Numerical results, based on the theory, are provided for examples of parallel and series circuits connected to a piezoelectric plate.

Acoustoelastic effect in stressed heterostructures.

Mechanical stresses influence the phase velocity of acoustic waves, known as the AE (acoustoelastic) effect. In order to calculate the AE effect of biaxially stressed layered systems, we extended the transfer matrix method for acoustic wave propagation by considering the change of the density, the influence of residual stress, and the modification of the elastic stiffness tensor by residual strain and by third-order constants. The generalized method is applied to the calculation of the angular dispersion of the AE effect for transverse bulk modes and surface acoustic waves on Ge(001).

Topological nature of the genetic code.

A model for topological coding of proteins is proposed. The model is based on the capacity of hydrogen bonds (property of connectivity) to fix conformations of protein molecules. The protein chain is modeled by an n -arc graph with the following elements: vertices (alpha -carbon atoms), structural edges (peptide bonds) and connectivity edges (virtual edges connecting non-adjacent atoms).

Non-linear algorithms based on SAFT ideas for reconstruction of flaws.

The main idea and the assumptions of time domain synthetic aperture focusing technique (SAFT) are discussed. It is underlined that the major SAFT assumption is that the flaw can be represented by a number of single non-interacting scalar point scatterers, which act as point sources after illumination with the incident wavefield. As a result some important classes of flaws are incorrectly reconstructed by means of SAFT.

Crystallization of the isobutylphosphocholine-cholesterol-isobutanol (1:3:3) complex and its investigation by X-ray analysis: interaction of phopholipid headgroups with cholesterol.

A crystal complex consisting of the isobutyl analog of phosphatidylcholine (PC) (isobutylphosphocholine), cholesterol, and isobutanol with molecular ratio 1:3:3 was obtained and investigated by means of X-ray analysis. The complex was shown to correspond to the monoclinic system (sp. gr.