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Alloys
Published in Alan Cottrell, An Introduction to Metallurgy, 2019
Below the critical temperature the domain boundaries have positive tensions and we may thus expect them to try to arrange themselves like films in a soap froth. From elementary experiences we know that in mechanically stable soap froths two bubbles (domains) meet across a surface, i.e. a soap film; three meet along a line, where three films join; and four meet at a corner, where four films meet at a point. This arrangement is impossible in an alloy such as CuZn, however, because there are only two different schemes of order, i.e. Cu on the β sub-lattice and Cu on the β sub-lattice, respectively. It is impossible for three different schemes of order to meet along a line, or four to meet at a point, because there are only two available. Hence a mechanically stable foam structure cannot be developed by the domain boundaries in CuZn. Domain growth can thus occur without hindrance once the temperature falls below Tc. Long-range order develops easily in this alloy.
Color from Interactions of Light Waves with Bulk Matter
Published in Mary Anne White, Physical Properties of Materials, 2018
A soap film is composed of soap molecules and water molecules. It is more energetically favorable for the soap molecules to have their hydrophobic ends away from the water pointing out into the air, which can, at appropriate concentration, give a bilayer structure, as shown schematically in Figure 4.14. The main difference between a thick soap film and a thin one is the number of water molecules between the soap layers.
Interfacial Catalysis at Oil/Water Interfaces
Published in Alexander G. Vdlkdv, Interfacial Catalysis, 2002
For decades, colloid and surface scientists have known that amphiphilic molecules such as phospholipids can self-assemble or self-organize themselves into supramolecular structures of bilayer lipid membranes (planar BLMs and spherical liposomes), emulsions, and micelles [2-4]. As a matter of fact, our current understanding of the structure and function of biomembranes can be traced to the studies of these experimental systems such as soap films and Langmuir monolayers, which have evolved as a direct consequence of applications of classical principles of colloid and interfacial chemistry. As already mentioned in Section I, the seminal work on the self-assembly of planar lipid bilayers and bilayer or “black” lipid membranes was carried out in 1959-1963. The idea started while one of the authors was reading a paperback edition of Soap Bubbles by C. V. Boys. These early researchers realized that a soap film in air in its final stage of thinning has a structure, which may be depicted as two monolayers sandwiching an aqueous surfactant solution. The picture of the so-called “black” soap films had been suggested many years ago by Gibbs, Overbeek, Mysels, Corkill, and others (see Ref. 2 and references cited therein). Rudin and coworkers showed that an underwater “soap film” or a BLM formed from brain extracts was self-sealing to puncture with many physical and chemical properties similar to those of biomembranes [3,4]. On modification with a certain protein, this otherwise electrically “inert” structure of about 6nm thick became excitable displaying characteristic features similar to those of action potentials of the nerve membrane. Thus, in the four plus decades since its inception, the conventional BLM along with the liposome has been extensively used as a model of biomembranes [3,4]. In particular, the BLMs have been adopted to elucidate the molecular mechanisms of biomembrane functions such as ion sensing, material transport, electrical excitability, gated channels, antigen-antibody binding, signal transduction, and energy conversion, to name a few. We will digress for a moment in the following paragraphs to describe biomembranes of the cell.
Instabilities of soap film structures in square cuboid frame
Published in Philosophical Magazine, 2020
Wang Chen, Chunhui Sha, Zuosheng Lei
The Evolver works in dimensionless units. Because surface energy is the only energy considered in our models, gravity is neglected, and the absolute value of the surface tension is unimportant. Films are assumed to be ideally dry, namely, have zero thickness. Therefore, all the liquid is in the Plateau borders or nodes. The liquid fraction of the soap film configuration is then given by the total volume of liquid divided by the volume of the square cuboid. In this paper, the disjoining pressure is not taken into consideration, which implies zero contact angle between the film and the adjacent Plateau border. The surface tension of the Plateau borders is set to a fixed bulk interfacial tension , and film tension is set to . Gradient descent method and Hessian iterations are used to minimise surface energy , where denotes the areas of the interfaces, and is either or , depending on whether the surface belongs to a Plateau border or a film.
Pierre-Gilles de Gennes and physics of liquid crystals
Published in Liquid Crystals Reviews, 2018
Further on, the scientist took interest in ‘soap bubbles’. He was attracted by the time dynamics of thinning process of their walls (soap films). The important de Gennes’ contribution to the theory of thinning of soap films was finding the analogy between the appearance of the lower thickness area in the film (the so-called stratification domain) and going out of a liquid (e.g. water) drop from the hydrophobic solid surface. The last phenomenon is called ‘dewetting’ and it is opposite to ‘wetting’. It was found that in both mentioned cases an excessive liquid was flowing through the edge bubbles, and the border of a stratification domain in a soap film, as well as a fluid drop front retreated from a hydrophobic surface possessed a constant velocity. The possibility of such analogy was first pointed out to de Gennes by F. Brochard-Wyart in 1987.
Soap films and GeoGebra in the study of Fermat and Steiner points
Published in International Journal of Mathematical Education in Science and Technology, 2018
To explain why the soap film was a minimal surface students used their own words and interpretations of the physical phenomenon they were observing. One team discussed in terms of the strength of the soap film and reported the results of their results to the whole group (names are pseudonyms). (In their small group)Amanda: I mean it makes sense that it would like minimize when it's as taut (makes pulling motion with both hands) as it can possible be.Daniel: So, it can be as thick as possible so it doesn't pop.Lynn: Yeah cause it's the same amount of soap and, all you do is change the radius, so it's gonna be the strongest when the soap is the smallest.Daniel: …Yeah, if the soap is strongest when it's thickest, it wants to minimize the amount of distance it has to cover.(To the whole class)Lynn: the strength of the film is gonna be the strongest when the film is the thickest and has the most amount of soap in that area (moves hands apart). And it's always the same amount of soap when you pull it out of, once it's out of the soap bucket, so therefore it's gonna pick the minimal distance so that there's the most amount of soap in the smallest amount of area so that way you get the biggest thickness or value.