Marangoni studies

Pitteri, B., Marangoni, G., Visentin, F., Bobbo, T., Bertolasi, V. and Gilli, P. (1999) Equilibrium and kinetic studies of (2,2 6, 2"-terpyridine)gold(III) complexes. Preparation and crystal structure of [Au(terpy)(0H)][C104]2. Journal of the Chemical Society, Dalton Transactions, (5), 677. 

An issue as interesting as it is contentious is that of electrolyte inhibition of bubble coalescence. Recently, a number of studies have reported the ion-specific nature of electrolyte inhibition of bubble coalescence, albeit in static (non-acoustic) fields [43 -9]. Some electrolytes appear to be highly efficacious whereas others almost completely ineffectual in inhibiting coalescence and ion combination rules have been devised to predict the behavior of various ion pairs. Various explanations have been proposed, most implying a gas-liquid interfacial mechanism. Christenson and Yaminsky [44] have reported a correlation between the inverse Marangoni factor, (dy/ dc]) 2, and coalescence inhibition ability for several different... 

CLSM is a relatively new method in food science. Several reviews discussing the application of this technique in microstructural studies of food products have been published recently (Heertje et al., 1987 Blonk and Vanaalst, 1993 Marangoni and Hartel, 1998). These reviews have shown the advantages of using CLSM over conventional techniques for study-... 

Several studies have explored the phase behavior of milk fat and its fractions (Mulder, 1953 Timms, 1980, 1984 Marangoni and Lencki, 1998). Milk fat composition is often discussed in terms of groups or fractions of TAGs, which are chemically and physically distinct (Timms, 1980 Bornaz et al., 1993 Marangoni and Lencki, 1998). For example, saturated and monounsaturated TAGs account for 65 mol% of the TAGs in milk fat... 

Wright, A.J., Narine, S.S., Marangoni, A.G. 2001a. Comparison of experimental techniques used in lipid crystallization studies. In, Crystallization and Solidification Properties of Lipids (N. Widlak, R. Hartel, S. Narine, eds.), pp. 120-131, AOCS Press, Champaign, IL. 

The study of wet steady-state foams has shown that the foam films at the upper layers rupture at very large thicknesses, i.e. before reaching thicknesses at which specific thermodynamic properties begin to appear [96]. Under these conditions the properties of wet steady-state foams are determined mainly by the effects of Marangoni and Gibbs, which stabilise kinetically the whole system [94-97,116,121,122]. 

Narine, S.S., and Marangoni, A.G. (1999b). Mieroscopic and rheological studies of fat crystal networks. J. Cryst. Growth. 198, 1315-1319. 

ZOpT can be used to study both self-similar and self-affine fractal objects. The data at low frequencies (u and v <10) is not to be included in the calculation of D j. Figure 17.25 from Tang and Marangoni (2006) illustrates how Df, and ZOpT are calculated from the double logarithmic plot ofX vs. Y for polarized light microscopy images of the fat crystal networks. 

Tang, D., and Marangoni, A.G. (2006). Quantitative study on the mierostrueture of colloid fat crystal networks and fractal dimensions. Advanees in Colloid and Interface Science. 

Electrophoresis of bubbles and drops is a story on its own. As long ago as 1861 Quincke ) observed the electrophoresis of small air bubbles in water. Such a motion is possible only when there is a double layer at the Interface, containing free ions. It is extremely difficult to keep oil-water or air-water Interfaces rigorously free from adsorbed ionic species. When these are present, especially for surfactants, Marangoni effects make the surface virtually inexten-slble then the drops or bubbles behave as solid spheres. Electrophoretic studies... 

Numerous studies have shown that mass transfer of solute from one phase to the other can alter the behavior of a liquid-liquid dispersion—because of interfacial tension gradients that form along the surface of a dispersed drop. For example, see Sawistowski and Goltz, Trans. Inst. Chem. Engrs., 41, p. 174 (1963) BaWcer, van Buytenen, and Beek, Chem Eng. Sci., 21(11), pp. 1039-1046 (1966) Rucken-stein and Berbente, Chem. Eng. Sci., 25(3), pp. 475—482 (1970) Lode and Heideger, Chem. Eng. Sci., 25(6), pp. 1081—1090 (1970) and Takeuchi and Numata, Int. Chem. Eng., 17(3), p. 468 (1977). These interfacial tension gradients can induce interfaci turbulence and circulation within drops. These effects, known as Marangoni instabilities, have been shown to enhance mass-transfer rates in certain cases. 

Capillarity phenomena are everyday occurrences that result from the existence of surface tension or interfacial tensions. In addition to the static phenomena discussed herein, surface tension and capillarity are also responsible for numerous dynamic phenomena that may result from localized gradients in temperatures or in compositions the study of dynamic capillary phenomena (e.g., Marangoni flows, Benard cells) is the subject of much literature coverage and is beyond the scope of this survey. 

Stemling and Scriven wrote the interfacial boundary conditions on nonsteady flows with free boundary and they analyzed the conditions for hydrodynamic instability when some surface-active solute transfer occurs across the interface. In particular, they predicted that oscillatory instability demands suitable conditions cmcially dependent on the ratio of viscous and other (heat or mass) transport coefficients at adjacent phases. This was the starting point of numerous theoretical and experimental studies on interfacial hydrodynamics (see Reference 4, and references therein). Instability of the interfacial motion is decided by the value of the Marangoni number, Ma, defined as the ratio of the interfacial convective mass flux and the total mass flux from the bulk phases evaluated at the interface. When diffusion is the limiting step to the solute interfacial transfer, it is given by... 

In the last two sections, we considered mass transfer from the film toward the droplets and the reverse, from droplets toward the film. In both cases, the diffusion fluxes lead to stabilization of the film. Here we consider the third possible case corresponding to mass transfer from the first droplet toward the second one across the film between them. In contrast with the former two cases, in the last case the mass transfer is found to destabilize the films. Experimentally, the diffusion transfer of alcohols, acetic acid, and acetone was studied. - The observed destabilization of the films can be attributed to the appearance of Marangoni instability, which manifests itself through the growth of capillary waves at the interfaces, which eventually can lead to film rupture. 

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