Inclusion of Viscosity Into Classical Homogeneous Nucleation Theory for Water Bubbles in Silicate Melts: Reexamination of Bubble Number Density in Ascending Magmas

Nishiwaki, Mizuki; Toramaru, Atsushi

doi:10.1029/2019jb017796

Cited by 6 publications

(2 citation statements)

References 45 publications

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“…The higher concentration of solids provided more nucleation sites, reducing the amount of undercooling required for nucleation. However, in 1.5 wt% collagen slurries, the increased viscosity was likely to have suppressed the formation of nuclei [ 46 ]. This effect might have outweighed the effects of the presence of increased nucleation sites, shifting the nucleation events to higher degrees of undercooling.…”

Section: Discussionmentioning

confidence: 99%

Controlling the Architecture of Freeze-Dried Collagen Scaffolds with Ultrasound-Induced Nucleation

Song,

Philpott,

Best

et al. 2024

Polymers

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Collagen is a naturally occurring polymer that can be freeze-dried to create 3D porous scaffold architectures for potential application in tissue engineering. The process comprises the freezing of water in an aqueous slurry followed by sublimation of the ice via a pre-determined temperature–pressure regime and these parameters determine the arrangement, shape and size of the ice crystals. However, ice nucleation is a stochastic process, and this has significant and inherent limitations on the ability to control scaffold structures both within and between the fabrication batches. In this paper, we demonstrate that it is possible to overcome the disadvantages of the stochastic process via the use of low-frequency ultrasound (40 kHz) to trigger nucleation, on-demand, in type I insoluble bovine collagen slurries. The application of ultrasound was found to define the nucleation temperature of collagen slurries, precisely tailoring the pore architecture and providing important new structural and mechanistic insights. The parameter space includes reduction in average pore size and narrowing of pore size distributions while maintaining the percolation diameter. A set of core principles are identified that highlight the huge potential of ultrasound to finely tune the scaffold architecture and revolutionise the reproducibility of the scaffold fabrication protocol.

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Section: Discussionmentioning

confidence: 99%

Controlling the Architecture of Freeze-Dried Collagen Scaffolds with Ultrasound-Induced Nucleation

Song,

Philpott,

Best

et al. 2024

Polymers

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“…This would reduce the theoretical value of BND by an order of magnitude. Nishiwaki and Toramaru (2019) indicated that, when the viscosity of the melt is high, it suppresses nucleation. The BND in Toramaru's (1995) viscosity-controlled regime may be overestimated.…”

Section: Future Directions In Microscopic Surface Tension Researchmentioning

confidence: 99%

Can spinodal decomposition occur during decompression-induced vesiculation of magma?

Nishiwaki

2024

Preprint

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Volcanic eruptions are driven by decompression-induced vesiculation of supersaturated volatile components in magma. The initial phase of this phenomenon has long been described as a phase of nucleation and growth. Recently, it was proposed that spinodal decomposition (an energetically spontaneous phase separation that does not require the formation of a distinct interface) may occur during decompression-induced magma vesiculation. This suggestion has attracted considerable attention and is currently only based on qualitative textural observations of decompression experiment products (the independence of bubble number density on decompression rate; the homogeneous spatial distribution of the bubbles). In this study, I used a simple thermodynamic approach to quantitatively investigate whether spinodal decomposition can occur during the decompression-induced vesiculation of magma. I drew the binodal and spinodal curves for each magma on the chemical composition-pressure plane by approaching hydrous magmas at several conditions of temperature and chemical composition as two-component symmetric regular solutions of silicate and water, and using experimentally determined values of water solubility in these magmas. The spinodal curve was much lower than the binodal curve for all the magmas at pressures sufficiently below the second critical endpoint (approximately less than 1000 MPa). In addition, the final pressure of all the decompression experiments performed to date fell between these two curves. This suggests that spinodal decomposition is unlikely to occur in the pressure range of magmatic processes in the continental crust or at realistic decompression rates, and that decompression-induced magma vesiculation results from nucleation, as previously suggested. To test this thermodynamic approach, I estimated the ‘microscopic’ surface tension between the melt and the bubble nucleus in previous decompression experiments by substituting the pressure of the spinodal curve into the equation for the dependence of surface tension on the degree of supersaturation. The resulting values were significantly more scattered than those obtained by the conventional method of inversion of the experimental bubble number density using the classical nucleation theory formula. Therefore, it is difficult to judge whether the equation of surface tension as a factor of supersaturation (based on the nonclassical nucleation theory) is appropriate for magma systems. Further careful consideration should be given to both experimental and theoretical aspects of magma vesiculation.

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Mechanism of Bubble Formation

Toramaru

2021

Vesiculation and Crystallization of Magma

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In the previous chapter, we learned that, for bubble generation, a supersaturated state is required. So, how do bubbles actually form in a supersaturated liquid? How do these bubbles grow to bubbles that we can see? To answer these questions and understand bubble formation, it is absolutely necessary for us to consider the meaning of the size and number of bubbles present in highly vesiculated volcanic rocks such as pumice and scoria, described in Chap. 1. These concepts are necessary for us to understand the dominant factors controlling eruption styles and intensity from the bubble texture in highly vesiculated volcanic rocks. In this chapter, we will understand the mechanisms of such bubble formation and behavior of bubbles in liquids based on both theories and experiments. Energetics of Bubble NucleationIn liquids that are supersaturated with a component that can vesiculate (a volatile component), nucleation is the process by which bubbles form embryos. In supersaturated liquids, nucleation does not always occur even if they are slightly supersaturated. Moreover, we already experience it at the table . When you open a bottle or a can of carbonated drinks that are gently carried, you will hear a soft pop and will not see active bubble formation. However, if you open a bottle or a can of the same drink that was subject to impact before opening, you know well that the results will be disastrous when you open it. As shown in Chap. 2, an opened bottle of beer is in supersaturation; however, it seems to require some special energy to vesiculate. In other words, an opened bottle of beer containing carbon dioxide can be stable because it is in supersaturation without work corresponding to the special energy. 1 If we assume that disturbance such as shock does work and gives the special energy required for vesiculation, we will realize what has happened. 1 The word stable used in this sentence actually means metastable. Water can be stable as liquid water even if it is cooled down to 0 • C, i.e., the freezing point. This state is a metastable state and such water is sometimes called supercooled water. Let us consider a metastable state from a point of view of energy under gravity as an analogy. When you place a cuboid on a horizontal plane, you can do it in two ways: where the longest sides are perpendicular to the horizontal plane and where the longest sides are parallel to the horizontal plane. Although the latter has lower potential energy and is stable, the former is stable unless pressed by an external force that is larger than a certain degree of force.

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Inclusion of Viscosity Into Classical Homogeneous Nucleation Theory for Water Bubbles in Silicate Melts: Reexamination of Bubble Number Density in Ascending Magmas

Cited by 6 publications

References 45 publications

Controlling the Architecture of Freeze-Dried Collagen Scaffolds with Ultrasound-Induced Nucleation

Controlling the Architecture of Freeze-Dried Collagen Scaffolds with Ultrasound-Induced Nucleation

Can spinodal decomposition occur during decompression-induced vesiculation of magma?

Mechanism of Bubble Formation

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