scholarly journals Nonlinear dynamics of mushy layers induced by external stochastic fluctuations

2018 ◽  
Vol 376 (2113) ◽  
pp. 20170216 ◽  
Author(s):  
Dmitri V. Alexandrov ◽  
Irina A. Bashkirtseva ◽  
Lev B. Ryashko
Keyword(s):  
Phase Transition ◽  
Liquid Phase ◽  
Analytical Solution ◽  
Friction Velocity ◽  
Solid Phase ◽  
Cumulative Effect ◽  
Atmospheric Temperature ◽  
Mushy Layer ◽  
Theme Issue ◽  
Stochastic Fluctuations

The time-dependent process of directional crystallization in the presence of a mushy layer is considered with allowance for arbitrary fluctuations in the atmospheric temperature and friction velocity. A nonlinear set of mushy layer equations and boundary conditions is solved analytically when the heat and mass fluxes at the boundary between the mushy layer and liquid phase are induced by turbulent motion in the liquid and, as a result, have the corresponding convective form. Namely, the ‘solid phase–mushy layer’ and ‘mushy layer–liquid phase’ phase transition boundaries as well as the solid fraction, temperature and concentration (salinity) distributions are found. If the atmospheric temperature and friction velocity are constant, the analytical solution takes a parametric form. In the more common case when they represent arbitrary functions of time, the analytical solution is given by means of the standard Cauchy problem. The deterministic and stochastic behaviour of the phase transition process is analysed on the basis of the obtained analytical solutions. In the case of stochastic fluctuations in the atmospheric temperature and friction velocity, the phase transition interfaces (mushy layer boundaries) move faster than in the deterministic case. A cumulative effect of these noise contributions is revealed as well. In other words, when the atmospheric temperature and friction velocity fluctuate simultaneously due to the influence of different external processes and phenomena, the phase transition boundaries move even faster. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’.

scholarly journals Response of the Surface Phase Transition to an Abrupt Pressure Change: Comparative Study of the 2D Gas–Liquid and 2D Fluid–Solid Phase Transitions

1998 ◽  
Vol 16 (5) ◽  
pp. 391-404 ◽  
Author(s):  
Yosihito Kitayama ◽  
Yosinobll Sakai ◽  
Hiromu Asada
Keyword(s):  
Phase Transition ◽  
Liquid Phase ◽  
Time Constant ◽  
Solid Phase ◽  
Pressure Change ◽  
Fast Decay ◽  
Liquid Phase Transition ◽  
Decay Component ◽  
Slow Decay ◽  
Solid Phase Transition

The manner in which gaseous CH4 and N2 respond to an abrupt pressure change through adsorption and desorption on exfoliated graphite held at a temperature between 77 K and 90 K has been studied with particular emphasis on the role of the 2D (two-dimensional) Gas–Liquid phase transition of the second layer of adsorbed CH4 and of the 2D Fluid–Solid phase transition of adsorbed N2. The pressure relaxation was found to consist of two exponential decay components: a fast one and a slow one. For CH4, the 2D Gas–Liquid phase transition is involved in the fast decay component with a time constant of 2–3 s, while the slow decay component with a time constant of 7–40 s is minor and has been attributed to ripening or coalescence processes in the adsorbed phase. In contrast, the 2D Fluid–Solid phase transition of N2 involves both the fast decay component with a time constant of 2–3 s and the slow decay component with a time constant of 14–16 s, both having nearly equal magnitudes. The difference in the pressure response between the two phase transitions is discussed.

n-pentanol at high pressures: Rotational isomerism in the liquid phase and the liquid-solid phase transition

2006 ◽  
Vol 124 (4) ◽  
pp. 044508 ◽  
Author(s):  
V. G. Baonza ◽  
M. Taravillo ◽  
A. Cazorla ◽  
S. Casado ◽  
M. Cáceres
Keyword(s):  
Phase Transition ◽  
Liquid Phase ◽  
High Pressures ◽  
Solid Phase ◽  
Rotational Isomerism ◽  
Solid Phase Transition

scholarly journals Verification of a mathematical model for the solution of the Stefan problem using the mushy layer method

2021 ◽  
Vol 2021 (3) ◽  
pp. 119-125
Author(s):  
R.S. Yurkov ◽  
◽  
L.I. Knysh ◽  
Keyword(s):  
Phase Transition ◽  
Liquid Phase ◽  
Stefan Problem ◽  
Heat Storage ◽  
Storage Systems ◽  
Phase Interface ◽  
Mushy Layer ◽  
Liquid Phase Transition ◽  
Layer Method ◽  
Solid Liquid

The use of solar energy has limitations due to its periodic availability: solar plants do not operate at night and are ineffective in dull weather. The solution of this problem involves the introduction of energy storage and duplication systems into the conversion loop. Among the energy storage systems, solid–liquid phase transition modules have significant energy, ecologic, and cost advantages. Physical processes in modules of this type are described by a system of non-stationary nonlinear partial differential equations with specific boundary conditions at the phase interface. The verification of a method for solving the Stefan problem for a heat-storage material is presented in this paper. The use of the mushy layer method made it possible to simplify the classical mathematical model of the Stefan problem by reducing it to a nonstationary heat conduction problem with an implicit heat source that takes into account the latent heat of transition. The phase transition is considered to occur in an intermediate zone determined by the solidus and liquidus temperatures rather than in in infinite region. To develop a Python code, use was made of an implicit computational scheme in which the solidus and liquidus temperatures remain constant and are determined in the course of numerical experiments. The physical model chosen for computer simulation and algorithm verification is the process of ice layer formation on a water surface at a constant ambient temperature. The numerical results obtained allow one to determine the temperature fields in the solid and the liquid phase and the position of the phase interface and calculate its advance speed. The algorithm developed was verified by analyzing the classical analytical solution of the Stefan problem for the one-dimensional case at a constant advance speed of the phase interface. The value of the verification coefficient was determined from a numerical solution of a nonlinear equation with the use of special built-in Python functions. Substituting the data for the physical model under consideration into the analytical solution and comparing them with the numerical simulation data obtained with the use of the mushy layer method shows that the results are in close agreement, thus demonstrating the correctness of the computer algorithm developed. These studies will allow one to adapt the Python code developed on the basis of the mushy layer method to the calculation of heat storage systems with a solid-liquid phase transition with account for the features of their geometry, the temperature level, and actual boundary conditions.

scholarly journals Liquid-liquid phase separation of full-length prion protein initiates conformational conversion in vitro

2020 ◽  
Author(s):  
Hiroya Tange ◽  
Daisuke Ishibashi ◽  
Takehiro Nakagaki ◽  
Yuzuru Taguchi ◽  
Yuji O. Kamatari ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Separation ◽  
Liquid Phase ◽  
Prion Protein ◽  
Solid Phase ◽  
Terminal Region ◽  
Liquid Phase Separation ◽  
Solid Phase Transition ◽  
Liquid Liquid Phase Separation

AbstractPrion diseases are characterized by accumulation of amyloid fibrils. The causative agent is an infectious amyloid that is comprised solely of misfolded prion protein (PrPSc). Prions can convert PrPC to proteinase-resistant PrP (PrP-res) in vitro; however, the intermediate steps involved in the spontaneous conversion remain unknown. We investigated whether recombinant prion protein (rPrP) can directly convert into PrP-res via liquid-liquid phase separation in the absence of PrPSc. We found that rPrP underwent liquid-liquid phase separation at the interface of the aqueous two-phase system (ATPS) of polyethylene glycol (PEG) and dextran, whereas single-phase conditions were not inducible. Fluorescence recovery assay after photobleaching revealed that the liquid-solid phase transition occurred within a short time. The aged rPrP-gel acquired proteinase-resistant amyloid accompanied by β-sheet conversion, as confirmed by western blotting, Fourier transform infrared spectroscopy, and Congo red staining. The reactions required both the N-terminal region of rPrP (amino acids 23-89) and kosmotropic salts, suggesting that the kosmotropic anions may interact with the N-terminal region of rPrP to promote liquid-liquid phase separation. Thus, structural conversion via liquid–liquid phase separation and liquid–solid phase transition are intermediate steps in the conversion of prions.

scholarly journals Sensitivity of Pore Collapse Heating to the Melting Temperature and Liquid-phase Shear Viscosity of HMX

2020 ◽  
Author(s):  
Matthew Kroonblawd ◽  
Ryan Austin
Keyword(s):  
Phase Transition ◽  
Liquid Phase ◽  
Melting Temperature ◽  
Shear Viscosity ◽  
Solid Phase ◽  
Scale Model ◽  
Pore Collapse ◽  
Liquid Phase Transition ◽  
Solid Liquid ◽  
Liquid Shear

A multiscale modeling strategy is used to quantify factors governing the temperature rise in hot spots formed by pore collapse from supported and unsupported shock waves in the high explosive HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). Two physical aspects are examined in detail, namely the melting temperature and liquid shear viscosity. All-atom molecular dynamics simulations of phase coexistence are used to predict the pressure-dependent melting temperature up to 5~GPa. Equilibrium simulations and the Green-Kubo formalism are used to obtain the temperature- and pressure-dependent liquid shear viscosity. Starting from a simplified continuum-based grain-scale model for HMX, we systematically increase the complexity of treatments for the solid-liquid phase transition and liquid shear viscosity in simulations of pore collapse. Using a realistic pressure-dependent melting temperature completely suppresses melting for supported shocks, which is otherwise predicted when treating it as a constant determined at atmospheric pressure. Alternatively, large melt pools form around pores during pressure release in unsupported shocks, even with a pressure-dependent melting temperature. Capturing the pressure dependence of the shear viscosity increases the peak temperature of melt pools by hundreds of Kelvin through viscous work. The complicated interplay of the solid-phase plastic work, solid-liquid phase transition, and liquid-phase viscous work identified here motivate taking a systematic approach to building increasingly complex grain-scale models and for guiding interpretation of predictions made using them.

scholarly journals Mathematical modeling of bulk and directional crystallization with the moving phase transition layer

2021 ◽  
Author(s):  
Liubov Toropova ◽  
Danil Aseev ◽  
Sergei Osipov ◽  
Alexander Ivanov
Keyword(s):  
Mathematical Modeling ◽  
Phase Transition ◽  
Transition Layer ◽  
Solid Phase ◽  
Phase Region ◽  
Mushy Region ◽  
Solidification Velocity ◽  
Mushy Layer ◽  
Two Phase ◽  
Phase Layer

This paper is devoted to the mathematical modeling of a combined effect of directional and bulk crystallization in a phase transition layer with allowance for nucleation and evolution of newly born particles. We consider two models with and without fluctuations in crystal growth velocities, which are analytically solved using the saddle-point technique. The particle-size distribution function, solid-phase fraction in a supercooled two-phase layer, its thickness and permeability, solidification velocity, and desupercooling kinetics are defined. This solution enables us to characterize the mushy layer composition. We show that the region adjacent to the liquid phase is almost free of crystals and has a constant temperature gradient. Crystals undergo intense growth leading to fast mushy layer desupercooling in the middle of a two-phase region. The mushy region adjacent to the solid material is filled with the growing solid phase structures and is almost desupercooled.

scholarly journals The Stefan problem in a thermomechanical context with fracture and fluid flow

2021 ◽  
Author(s):  
Tomáš Roubíček
Keyword(s):  
Phase Transition ◽  
Liquid Phase ◽  
Stefan Problem ◽  
Solid Phase ◽  
Phase Field Model ◽  
Liquid Phase Transition ◽  
Time Discretisation ◽  
Eulerian Description ◽  
Solid Liquid ◽  
Viscoelastic Rheology

The classical Stefan problem, concerning mere heat-transfer during solid-liquid phase transition, is here enhanced towards mechanical effects. The Eulerian description at large displacements is used with convective and Zaremba-Jaumann corotational time derivatives, linearized by exploiting the additive Green-Naghdi’s decomposition in (objective) rates. In particular, the liquid phase is a viscoelastic fluid while creep and rupture of the solid phase is considered in the Jeffreys viscoelastic rheology exploiting the phase-field model, exploiting a concept of slightly (so-called “semi”) compressible materials. The $L^1$-theory for the heat equation is adopted for the Stefan problem relaxed by allowing for kinetic superheating/supercooling effects during the solid-liquid phase transition. A rigorous proof of existence of week solutions is provided for an incomplete melting, exploiting a time-discretisation approximation.

Sensitivity of Pore Collapse Heating to the Melting Temperature and Liquid-phase Shear Viscosity of HMX

2020 ◽  
Author(s):  
Matthew Kroonblawd ◽  
Ryan Austin
Keyword(s):  
Phase Transition ◽  
Liquid Phase ◽  
Melting Temperature ◽  
Shear Viscosity ◽  
Solid Phase ◽  
Scale Model ◽  
Pore Collapse ◽  
Liquid Phase Transition ◽  
Solid Liquid ◽  
Liquid Shear

A multiscale modeling strategy is used to quantify factors governing the temperature rise in hot spots formed by pore collapse from supported and unsupported shock waves in the high explosive HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). Two physical aspects are examined in detail, namely the melting temperature and liquid shear viscosity. All-atom molecular dynamics simulations of phase coexistence are used to predict the pressure-dependent melting temperature up to 5~GPa. Equilibrium simulations and the Green-Kubo formalism are used to obtain the temperature- and pressure-dependent liquid shear viscosity. Starting from a simplified continuum-based grain-scale model for HMX, we systematically increase the complexity of treatments for the solid-liquid phase transition and liquid shear viscosity in simulations of pore collapse. Using a realistic pressure-dependent melting temperature completely suppresses melting for supported shocks, which is otherwise predicted when treating it as a constant determined at atmospheric pressure. Alternatively, large melt pools form around pores during pressure release in unsupported shocks, even with a pressure-dependent melting temperature. Capturing the pressure dependence of the shear viscosity increases the peak temperature of melt pools by hundreds of Kelvin through viscous work. The complicated interplay of the solid-phase plastic work, solid-liquid phase transition, and liquid-phase viscous work identified here motivate taking a systematic approach to building increasingly complex grain-scale models and for guiding interpretation of predictions made using them.

Identification of hepatitis a virus in cell cultures by solid phase immune electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 238-239
Author(s):  
C.D. Humphrey ◽  
T.L. Cromeans ◽  
E.H. Cook ◽  
D.W. Bradley
Keyword(s):  
Electron Microscopy ◽  
Liquid Phase ◽  
Cell Cultures ◽  
Rapid Detection ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Solid Phase ◽  
Immune Electron Microscopy ◽  
Detection And Identification

There is a variety of methods available for the rapid detection and identification of viruses by electron microscopy as described in several reviews. The predominant techniques are classified as direct electron microscopy (DEM), immune electron microscopy (IEM), liquid phase immune electron microscopy (LPIEM) and solid phase immune electron microscopy (SPIEM). Each technique has inherent strengths and weaknesses. However, in recent years, the most progress for identifying viruses has been realized by the utilization of SPIEM.

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