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Wyszukujesz frazę "Postema, M." wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
Lagrangian formalism for computing oscillations of spherically symmetric encapsulated acoustic antibubbles
Autorzy:
Johansen, K.
Postema, M.
Powiązania:
https://bibliotekanauki.pl/articles/332496.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
microbubbles
spatio–temporal bubble dynamics
Rayleigh-Plesset equation
Opis:
Antibubbles are gas bubbles containing a liquid droplet core and, typically, a stabilising outer shell. It has been hypothesised that acoustically driven antibubbles can be used for active leakage detection from subsea production facilities. This paper treats the dynamics of spherically symmetric microscopic antibubbles, building on existing models of bubble dynamics. A more complete understanding of microbubble dynamics demands that the effects of the translational dynamics is included into the Rayleigh-Plesset equation, which has been the primary aim of this paper. Moreover, it is a goal of this paper to derive a theory that is not based on ad-hoc parameters due to the presence of a shell, but rather on material properties. To achieve a coupled set of differential equations describing the radial and translational dynamics of an antibubble, in this paper Lagrangian formalism is used, where a Rayleigh-Plesset-like equation allows for the shell to be modelled from first principles. Two shell models are adopted; one for a Newtonian fluid shell, and the other for a Maxwell fluid shell. In addition, a zero-thickness approximation of the encapsulation is presented for both models. The Newtonian fluid shell can be considered as a special case of the Maxwell fluid shell. The equations have been linearised and the natural and damped resonance frequencies have been presented for both shell models.
Źródło:
Hydroacoustics; 2016, 19; 197-207
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theory of Red Blood Cell Oscillations in an Ultrasound Field
Autorzy:
Johansen, K.
Kimmel, E.
Postema, M.
Powiązania:
https://bibliotekanauki.pl/articles/178064.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
spatio-temporal cell dynamics
Rayleigh-Plesset equation
spherical cell
red blood cell
erythrocyte
sonophore
Opis:
Manipulating particles in the blood pool with noninvasive methods has been of great interest in therapeutic delivery. Recently, it was demonstrated experimentally that red blood cells can be forced to translate and accumulate in an ultrasound field. This acoustic response of the red blood cells has been attributed to sonophores, gas pockets that are formed under the influence of a sound field in the inner-membrane leaflets of biological cells. In this paper, we propose a simpler model: that of the compressible membrane. We derive the spatio-temporal cell dynamics for a spherically symmetric single cell, whilst regarding the cell bilayer membrane as two monolayer Newtonian viscous liquids, separated by a thin gas void. When applying the newly-derived equations to a red blood cell, it is observed that the void inside the bilayer expands to multiples of its original thickness, even at clinically safe acoustic pressure amplitudes. For causing permanent cell rupture during expansion, however, the acoustic pressure amplitudes needed would have to surpass the inertial cavitation threshold by a factor 10. Given the incompressibility of the inner monolayer, the radial oscillations of a cell are governed by the same set of equations as those of a forced antibubble. Evidently, these equations must hold for liposomes under sonication, as well.
Źródło:
Archives of Acoustics; 2017, 42, 1; 121-126
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bubble-Like Response of Living Blood Cells and Microparticles in an Ultrasound Field
Autorzy:
Mazzawi, N.
Postema, M.
Kimmel, E.
Powiązania:
https://bibliotekanauki.pl/articles/1383573.pdf
Data publikacji:
2015-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.80.Cs
47.55.df
87.80.Fe
Opis:
The bilayer sonophore model suggests that ultrasound induces a pulsating structure in the intra-membrane hydrophobic space between the two lipid monolayer leaflets of the cell membrane, assembled by dissolved gas of the surrounding area, which absorbs acoustic energy and transforms it by creating intra-cellular structural changes. This void has been referred to as a bilayer sonophore. The bilayer sonophore inflates and deflates periodically when exposed to ultrasound and may itself radiate acoustic pressure pulses in the surrounding medium in the same way a gas bubble does: once exposed to ultrasound the bilayer sonophore becomes a mechanical oscillator and a source of intracellular cavitation activity. In this paper, we describe observations of the clustering behaviour of living cells and several other particles in a standing sound field generated inside a ring transducer. Upon sonication, blood cells and monodisperse polystyrene particles were observed to have been trapped in the same locations, corresponding to nodes of the ultrasound field. Because polystyrene is hydrophobic, it behaves like a particle trapped inside a thin gas shell. In fact, the sonophore model treats biological cells in a similar way. Microbubbles that form the ultrasound contrast agent Quantison™ behave differently, however. These microbubbles accumulated in circles faster than blood cells and polystyrene particles. In addition, they form tightly packed clusters at the nodes, indicating very strong secondary Bjerknes forces. Cluster formation is not to be expected in cells with predicted sonophore sizes on the order of 10-100 nm.
Źródło:
Acta Physica Polonica A; 2015, 127, 1; 103-105
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustically Active Antibubbles
Autorzy:
Kotopoulis, S.
Johansen, K.
Gilja, O.
Poortinga, A.
Postema, M.
Powiązania:
https://bibliotekanauki.pl/articles/1383564.pdf
Data publikacji:
2015-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
47.55.dd
43.25.Yw
43.80.Sh
Opis:
In this study, we analyse the behaviour of antibubbles when subjected to an ultrasonic pulse. Specifically, we derive oscillating behaviour of acoustic antibubbles with a negligible outer shell, resulting in a Rayleigh-Plesset equation of antibubble dynamics. Furthermore, we compare theoretical behaviour of antibubbles to behaviour of regular gas bubbles. We conclude that antibubbles and regular bubbles respond to an acoustic wave in a very similar manner if the antibubble's liquid core radius is less than half the antibubble radius. For larger cores, antibubbles demonstrate highly harmonic behaviour, which would make them suitable vehicles in ultrasonic imaging and ultrasound-guided drug delivery.
Źródło:
Acta Physica Polonica A; 2015, 127, 1; 99-102
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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