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Acoustic Estimation of Resonance Frequency and Sonodestruction of SonoVue Microbubbles

Jurkonis R., Lamanauskas N., Šatkauskas S.

Archives of Acoustics

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2015

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Vol. 40, No. 3

293--300

EN

Acoustic properties of ultrasound (US) contrast agent microbubbles (MB) highly influence sonoporation efficiency and intracellular drug and gene delivery. In this study we propose an acoustic method to monitor passive and excited MBs in a real time. MB monitoring system consisted of two separate transducers. The first transducer delivered over an interval of 1 s US pulses (1 MHz, 1% duty cycle, 100 Hz repetition frequency) with stepwise increased peak negative pressure (PNP), while the second one continuously monitored acoustic response of SonoVue MBs. Pulse echo signals were processed according to the substitution method to calculate attenuation coefficient spectra and loss of amplitude. During US exposure at 50–100 kPa PNP we observed a temporal increase in loss of amplitude which coincided with the US delivery. Transient increase in loss of amplitude vanished at higher PNP values. At higher PNP values loss of amplitude decreased during the US exposure indicating MB sonodestruction. Analysis of transient attenuation spectra revealed that attenuation coefficient was maximal at 1.5 MHz frequency which is consistent with resonance frequency of SonoVue MB. The method allows evaluation of the of resonance frequency of MB, onset and kinetics of MB sonodestruction.

2

Rayleigh-Lamb waves in micropolar thermoelastic plate coated with inviscid fluid

Kumar R., Partap G.

International Journal of Applied Mechanics and Engineering

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2011

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Vol. 16, no 3

709-729

EN

The propagation of Rayleigh-Lamb waves in a micropolar generalized thermoelastic plate coated with an inviscid fluid is investigated in the context of Lord and Shulman (L-S), Green and Lindsay (G-L) and Chandrasekhariah and Tzou (C-T) theories of thermoelasticity. The secular equations for the symmetric and skew-symmetric mode propagation are derived. The regions and short wavelength waves of secular equations are also discussed. At short wavelength limits, the secular equations reduce to the Rayleigh surface wave frequency equation. Finally, the numerical solution is carried out for a magnesium crystal composite material plate coated with water layers. The dispersion curves, attenuation coefficients and amplitudes of stresses and temperature distribution for symmetric and skew-symmetric wave modes are computed analytically and presented graphically. This work could be useful in underwater acoustics. The present study has immense applications to defence science, mainly in geophysical problems, such as water-covered or oil-covered layers in the earth's crust.

3

Property of Materials on Wave Propagation in Microstretch Generalized Thermoelastic Solid

Gupta R. R., Kumar R.

Mechanics and Mechanical Engineering

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2009

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Vol. 13, nr 1

91-112

EN

The present paper is aimed at studying the effect of temperature dependent properties of elastic materials on wave propagation in a microstretch generalized thermoelastic solid. The mathematical model has been simplified by using the Helmholtz decomposition technique and secular equations connecting phase velocity with wave number, for symmetric and skew symmetric wave modes are derived. Phase velocity, attenuation coefficients, amplitude ratios and specific loss are obtained. The results obtained are compared with those obtained by author previous work. Finally, in order to illustrate the analytical developments, the numerical solution of secular equations, amplitude ratios and specific loss with wave number for different angle of inclination is carried out for magnesium crystal material with the help of Cardon's method. This type of study has many applications in various fields of science and technology.

4

Analysis of free vibrations for Rayleigh lamb waves in a micropolar viscoelastic plate

Kumar R., Partap G.

International Journal of Applied Mechanics and Engineering

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2008

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Vol. 13, no 2

383-397

EN

The propagation of free vibrations in a homogeneous isotropic micropolar viscoelastic plate subjected to stress free conditions is investigated. The secular equations for symmetric and skew symmetric wave mode propagation are derived. The regions of secular equations are obtained and special cases such as Lame modes, thin plate results and short wavelength waves are also discussed. At short wavelength limit, the secular equations for symmetric and skew symmetric waves in a stress free plate reduce to the Rayleigh surface wave frequency equation. The amplitudes of normal force stress, tangential force stress and tangential couple stress are obtained and depicted graphically. Finally, numerical solution is carried out for magnesium crystal composite material plate.