共查询到20条相似文献,搜索用时 15 毫秒
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The onset of intermediate states (denaturation bubbles) and their role during the melting transition of DNA are studied using the Peyrard-Bishop-Dauxois model by Monte Carlo simulations with no adjustable parameters. Comparison is made with previously published experimental results finding excellent agreement. Melting curves, critical DNA segment length for stability of bubbles, and the possibility of a two-state transition are studied. 相似文献
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Motivated by the “new inflationary universe scenario”, we have made a detailed study of the bubble nucleation process in (nearly) Coleman-Weinberg models with small positive scalar field mass terms. Our goal has been to show the consistency and interrelation between Coleman's analysis of bubble nucleation in flat space, the work of Coleman and De Luccia on bubble nucleation with gravitational effects and the recent dramatically different results of Hawking and Moss on bubble nucleation in Coleman-Weinberg models in a de Sitter background. Many of our results apply to more general classes of potentials. 相似文献
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O. Yavas A. Schilling J. Bischof J. Boneberg P. Leiderer 《Applied Physics A: Materials Science & Processing》1997,64(4):331-339
with a pressure pulse width of . Additionally, the phase of an acoustic pulse is observed to change upon reflection at the liquid–solid interface if bubbles
are present, providing a direct proof for laser-induced bubbles.
Received: 5 December 1996/Accepted: 6 January
1997 相似文献
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H. N. Yoshikawa F. Zoueshtiagh H. Caps P. Kurowski P. Petitjeans 《The European physical journal. E, Soft matter》2010,31(2):191-199
The stability of centimeter scale air bubbles is studied in quiescent suspending liquid under an imposed oscillatory acceleration
field. Experiments were performed in reduced- and normal-gravity environments. A strong acceleration resulted in an instability
leading to the breakups of the bubbles in both gravity environments. The breakup onset was investigated and found to be characterized
by a critical acceleration a
cr . The influence of the liquid viscosity and the gravitational environment was studied. Empirical correlations for the onset
are presented and discussed with the intention to reveal splitting mechanism. The inertial mechanism often deemed to cause
the breakup of drops subjected to a rapid gas stream is shown to give explanations consistent with the experiments. A breakup
criterion for both gravitational environments is proposed through discussions from an energetic point of view. 相似文献
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G. Münster S.B. Rutkevich 《The European Physical Journal C - Particles and Fields》2003,27(2):297-303
In many systems in condensed matter physics and quantum field theory, first order phase transitions are initiated by the
nucleation of bubbles of the stable phase. In homogeneous nucleation theory the nucleation rate can be written in the form of the Arrhenius law: . Here is the energy of the critical bubble, and the prefactor can be expressed in terms of the determinant of the operator of fluctuations near the critical bubble state. In general it
is not possible to find explicit expressions for and . If the difference between the energies of the stable and metastable vacua is small, the constant can be determined within the leading approximation in , which is an extension of the ”thin wall approximation”. We have done this calculation for the case of a model with a real-valued
order parameter in two dimensions.
Received: 11 September 2002 / Revised version: 30 October 2002 / Published online: 24 January 2003
RID="a"
ID="a" e-mail: munsteg@uni-muenster.de
RID="b"
ID="b" e-mail: rut@ifttp.bas-net.by
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Present address: Universit?t Essen, Fachbereich 7 - Physik, Universit?tsstr. 5, 45117 Essen, Germany 相似文献
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Sear RP 《J Phys Condens Matter》2012,24(5):052205
We study the nucleation of a new thermodynamic phase in the presence of quenched disorder. The quenched disorder is a generic model of both impurities and disordered porous media; both are known to have large effects on nucleation. We find that the nucleation rate is non-self-averaging. This is in a simple Ising model with clusters of quenched spins. We also show that non-self-averaging behaviour is straightforward to detect in experiments, and may be rather common. 相似文献
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Nanobubbles on a hydrophilic surface immersed in water and ethanol are inferred from the response of the surface to two consecutive heat pulses with a variable separation time. Bubble nucleation occurs at specific positions on the surface during the first heat pulse but at lower nucleation temperatures and random locations on the second. Nanobubbles are hypothesized to form on collapse of the bubble from the first pulse. 相似文献
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Colloidal suspensions of charged latex microspheres in water exhibit liquid-like or crystalline ordering depending on particle interaction and concentration. By virtue of large particle spacing and slow dynamics, colloidal systems offer a unique opportunity to study interfacial structure and dynamics. This paper presents the first reported experimental study of the nucleation rate density, c, of an nonequilibrium (supercooled) colloidal liquid to colloidal crystal first order phase transition. Local and global observations of colloidal crystals growing from a metastable colloidal liquid were used to determine c. Microscopic local observations revealed homogeneous nucleation and constant interface velocity growth of quasispherical crystallites in the bulk and heterogeneous nucleation of a crystalline sheet with lower growth velocity at the cell wall. Complementary global observations of the recrystallization transition made by measuring the time dependence of the suspension transparency (the fraction of transmitted laser light) determined c by fitting this curve to a model based on an extension of Avrami's theory of crystallization. 相似文献
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A metastable lattice gas with nearest-neighbor interactions and continuous-time dynamics is studied using a generalized Becker-D?ring approach in the multidimensional space of cluster configurations. The preexponential of the metastable-state lifetime (inverse of nucleation rate) is found to exhibit distinct peaks at integer values of the inverse supersaturation. Peaks are unobservable (infinitely narrow) in the strict limit T-->0, but become detectable and eventually dominate at higher temperatures. 相似文献
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The effect of the heating rate on the nucleation of metallic glass in a rapid heating process starting from the glass transition temperature is investigated. The critical nucleus radius increases with the increase of the temperature of the undercooling liquid. If the increment rate of the critical nucleus radius, owing to the heating process, is higher than the growth rate of the nuclei, the nuclei generated at the low temperature will become the embryos at the high temperature. This means that the high heating rate can make no nucleation happen in the heating process. In consideration of the interfacial energy, the growth rate of the nuclei increases with the increase of their size and the growth rate of the critical nucleus is zero. Thus, the lower heating rate can also make the nuclei decline partially. Finally, this theory is used to analyze the nucleation process during laser remelting metallic glass. 相似文献