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Bagdoev A.G.,Armenian National Academy of Sciences | Vardanyan A.V.,Armenian National Academy of Sciences | Vardanyan S.V.,Armenian National Academy of Sciences | Martirosyan A.N.,Goris State University
Multidiscipline Modeling in Materials and Structures | Year: 2010

Purpose - The purpose of this paper is to investigate the problem of fracture of construction by solution of several mixed unsteady boundary value problems of elasticity, determination of stress intensity factors and concentration of stresses near edges of cracks and by numerical calculations of them obtained by explicit formulae. Design/methodology/approach - The main methods of solution are integral transformations of Laplace and Fourier, method of Winner-Hopf system solution by avoiding the singularities of coefficients of their matrices and factorization of them using numerical solution of the same order system of Fredholm integral equations. The solution for stresses is obtained in originals by effective Smirnov-Sobolev form. The obtained integrals for stress intensity coefficients are calculated for considered cases of plane and anti-plane problems of cracks, and for more complex space problem of crack are carried out all mentioned analytical investigations, including derivation of stresses distributions formulae near crack edge. Findings - These analytic and numerical methods based on dynamic elasticity approximation on account of singularities near cracks edge allow precise calculation of the possibility and character of fracture of media under any loading of rather complex type. Originality/value - Results can be useful for investigation of constructions responsibility. The developed mathematical methods are original and modern, using all actual effective methods of investigation of solutions of linear system of equations with three and four independent variables for complex initial, boundary value problems. © Emerald Group Publishing Li.

Grigoryan Z.A.,Goris State University | Karapetyan A.T.,Yerevan State University of Architecture and Construction
Journal of Contemporary Physics | Year: 2014

The behavior of a mixture of short fragments of double-stranded DNA and a flexible-chain polymer is addressed. The role of the DNA double helix in the formation of the crystalline phase in the flexible-chain polymer’s melt is examined. It is shown that the presence of DNA rigid fragments in melt results in increase in the melting temperature. A shift of the melting temperature of a perfect crystal with respect to the pure melt of polymer is calculated. © 2014, Allerton Press, Inc.

Grigoryan Z.A.,Goris State University
Journal of Contemporary Physics | Year: 2014

Phase behavior of short double-stranded DNA molecules dissolved in the water-containing polymer matrix is considered theoretically. Flexible-chain polymer molecules are assumed to be neutral. The phase behavior of DNA fragments is shown to be governed by the effective attraction, occurring due to polyvalent cations dissolved in water, and the osmotic pressure of the flexible-chain polymer. © 2014 Allerton Press, Inc.

Grigoryan Z.A.,Goris State University | Karapetian A.T.,Yerevan State University of Architecture and Construction
Biophysical Reviews and Letters | Year: 2015

It is shown that the molecules of double - stranded DNA form a liquid-crystaline ordered phase, depending on the value of parameter of Flory-Huggins, DNA aspect ratio, energy of attraction between the molecules of DNA and volume fraction of the flexible polymer. Liquid crystalline order formation in double-stranded DNA, immeresed in the polymeric matrix occurs with increase of the volume fraction of the flexible polymer. The orrdered phase formation in double-stranded DNA is governed by volume fraction of DNA and by temperature. The results clearly show the effect of the polymer matrix on the ordering in DNA molecules. © World Scientific Publishing Company.

Karapetian A.T.,Yerevan State University of Architecture and Construction | Grigoryan Z.A.,Goris State University | Mamasakhlisov Y.S.,Yerevan State University | Minasyants M.V.,Yerevan State University | Vardevanyan P.O.,Yerevan State University
Journal of Biomolecular Structure and Dynamics | Year: 2016

The melting transition of DNA-ligand complexes, allowing for two binding mechanisms to different DNA conformations is treated theoretically. The obtained results express the behavior of the experimentally measurable quantities, degree of denaturation, and concentrations of bound ligands on the temperature. The range of binding parameters is obtained, where denaturation curves become multiphasic. The possible application to the nanocomposites crystallization is discussed. © 2015 Taylor and Francis.

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