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Foam
Foams are two-phase materials science, material systems where a gas is dispersed in a second, non-gaseous material, specifically, in which gas cells are enclosed by a distinct liquid or solid material. Note, this source focuses only on liquid foams. Note, this source also focuses on liquid foams. Foam "may contain more or less liquid [or solid] according to circumstances", although in the case of gas-liquid foams, the gas occupies most of the volume. In most foams, the volume of gas is large, with thin films of liquid or solid separating the regions of gas. Etymology The word derives from the Old High German, medieval German and otherwise obsolete ''veim'', in reference to the "frothy head forming in the glass once the beer has been freshly poured" (cf. ''ausgefeimt''). Structure A foam is, in many cases, a multi-scale system. One scale is the bubble: materials science, material foams are typically randomness, disordered and have a variety of bubble sizes. At larger siz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weaire–Phelan Structure
In geometry, the Weaire–Phelan structure is a three-dimensional structure representing an idealised foam of equal-sized bubbles, with two different shapes. In 1993, Denis Weaire and Robert Phelan found that this structure was a better solution of the Kelvin problem of tiling space by equal volume cells of minimum surface area than the previous best-known solution, the Kelvin structure. History and the Kelvin problem In two dimensions, the subdivision of the plane into cells of equal area with minimum average perimeter is given by the hexagonal tiling, but although the first record of this honeycomb conjecture goes back to the ancient Roman scholar Marcus Terentius Varro (116-27 BCE), it was not proven until the work of Thomas C. Hales in 1999. In 1887, Lord Kelvin asked the corresponding question for three-dimensional space: how can space be partitioned into cells of equal volume with the least area of surface between them? Or, in short, what was the most efficient soap bubbl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surfactant
Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word ''surfactant'' is a Blend word, blend of "surface-active agent", coined in 1950. As they consist of a water-repellent and a water-attracting part, they enable water and oil to mix; they can form foam and facilitate the detachment of dirt. Surfactants are among the most widespread and commercially important chemicals. Private households as well as many industries use them in large quantities as detergent, detergents and cleaning agents, but also for example as emulsion#Emulsifiers, emulsifiers, wetting agents, foaming agents, Antistatic agent, antistatic additives, or dispersants. Surfactants occur naturally in traditional plant-based detergents, e.g. Aesculus, horse chestnuts or Sapindus, soap nuts; they can also be found in the secretions of some caterpillars. Today one of the most commonly used anionic surfa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dispersed Media
A dispersion is a system in which distributed particles of one material are dispersed in a continuous phase of another material. The two phases may be in the same or different states of matter. Dispersions are classified in a number of different ways, including how large the particles are in relation to the particles of the continuous phase, whether or not precipitation occurs, and the presence of Brownian motion. In general, dispersions of particles sufficiently large for sedimentation are called suspensions, while those of smaller particles are called colloids and solutions. Structure and properties It is widely assumed that dispersions do not display any structure; i.e., the particles (or in case of emulsions: droplets) dispersed in the liquid or solid matrix (the "dispersion medium") are assumed to be statistically distributed. Therefore, for dispersions, usually percolation theory is assumed to appropriately describe their properties. However, percolation theory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tessellations
A tessellation or tiling is the covering of a surface, often a plane (mathematics), plane, using one or more geometric shapes, called ''tiles'', with no overlaps and no gaps. In mathematics, tessellation can be generalized to high-dimensional spaces, higher dimensions and a variety of geometries. A periodic tiling has a repeating pattern. Some special kinds include ''regular tilings'' with regular polygonal tiles all of the same shape, and ''semiregular tilings'' with regular tiles of more than one shape and with every corner identically arranged. The patterns formed by periodic tilings can be categorized into 17 wallpaper groups. A tiling that lacks a repeating pattern is called "non-periodic". An ''aperiodic tiling'' uses a small set of tile shapes that cannot form a repeating pattern (an aperiodic set of prototiles). A ''tessellation of space'', also known as a space filling or honeycomb, can be defined in the geometry of higher dimensions. A real physical tessellation is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colloid
A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend the definition to include substances like aerosols and gels. The term colloidal suspension refers unambiguously to the overall mixture (although a narrower sense of the word '' suspension'' is distinguished from colloids by larger particle size). A colloid has a dispersed phase (the suspended particles) and a continuous phase (the medium of suspension). The dispersed phase particles have a diameter of approximately 1 nanometre to 1 micrometre. Some colloids are translucent because of the Tyndall effect, which is the scattering of light by particles in the colloid. Other colloids may be opaque or have a slight color. Colloidal suspensions are the subject of interface and colloid science. This field of study began in 1845 by Franc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plateau's Laws
Plateau's laws describe the structure of soap films. These laws were formulated in the 19th century by the Belgian physicist Joseph Plateau from his experimental observations. Many patterns in nature are based on foams obeying these laws. Laws for soap films Plateau's laws describe the shape and configuration of soap films as follows: # Soap films are made of entire (unbroken) smooth surfaces. # The mean curvature of a portion of a soap film is everywhere constant on any point on the same piece of soap film. # Soap films always meet in threes along an edge called a Plateau border, and they do so at an angle of arccos(−) = 120°. # These Plateau borders meet in fours at a vertex, at the tetrahedral angle of arccos(−) ≈ 109.47°. Configurations other than those of Plateau's laws are unstable, and the film will quickly tend to rearrange itself to conform to these laws. That these laws hold for minimal surfaces was proved mathematically by Jean Taylor using geom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bubble (physics)
A bubble is a :wikt:globule, globule of a gas substance in a liquid. In the opposite case, a globule of a liquid in a gas, is called a drop (liquid), drop. Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance. Common examples Bubbles are seen in many places in everyday life, for example: * As spontaneous nucleation of supersaturated carbon dioxide in soft drinks * As vapor in boiling water * As air mixed into agitated water, such as below a waterfall * As sea foam * As a soap bubble * As given off in chemical reactions, e.g., baking soda + vinegar * As a gas trapped in glass during its manufacture * As the indicator in a spirit level * As bubble gum Physics and chemistry Bubbles form and coalesce into globular shapes because those shapes are at a lower energy state. For the physics and chemistry behind it, see nucleation. Appearance Bubbles are visible because they have a different refractive index (RI) than the surrou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Materials Science
Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials science stem from the Age of Enlightenment, when researchers began to use analytical thinking from chemistry, physics, and engineering to understand ancient, phenomenological observations in metallurgy and mineralogy. Materials science still incorporates elements of physics, chemistry, and engineering. As such, the field was long considered by academic institutions as a sub-field of these related fields. Beginning in the 1940s, materials science began to be more widely recognized as a specific and distinct field of science and engineering, and major technical universities around the world created dedicated schools for its study. Materials scientists emphasize understanding how the history of a material (''processing'') influences its struc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyancy
Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus, the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the Displacement (fluid), displaced fluid. For this reason, an object with average density greater than the surrounding fluid tends to sink because its weight is greater than the weight of the fluid it displaces. If the objec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isabelle Cantat
Isabelle Cantat (née Durand, born 1974) is a French physicist specializing in foams and their fluid dynamics. She is a professor in the Institute of Physics of Rennes at the Education and career Cantat was born on 5 January 1974 in Rennes. She earned an agrégation in physics in 1996 through study at the École normale supérieure de Lyon. She completed a doctorate in 1999 and a habilitation in 2006. After postdoctoral research at Heinrich Heine University Düsseldorf in Germany, she became maître de conférences in the Groupe Matière Condensée et Matériaux (GMCM) at the University of Rennes 1, which later became part of the Institute of Physics of Rennes (IPR). In 2007 she was promoted to professor. Book Cantat is a coauthor of the book ''Foams: Structure and Dynamics'' (Oxford University Press, 2013, with Sylvie Cohen-Addad, Florence Elias, François Graner, Reinhard Höhler, Olivier Pitois, Florence Rouyer, Arnaud Saint-Jalmes, and Simon Cox). Recognition Cantat was na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Work (physics)
In science, work is the energy transferred to or from an Physical object, object via the application of force along a Displacement (vector), displacement. In its simplest form, for a constant force aligned with the direction of motion, the work equals the Product (mathematics), product of the force strength and the distance traveled. A force is said to do ''positive work'' if it has a component in the direction of the displacement of the point of application. A force does ''negative work'' if it has a component opposite to the direction of the displacement at the point of application of the force. For example, when a ball is held above the ground and then dropped, the work done by the gravitational force on the ball as it falls is positive, and is equal to the weight of the ball (a force) multiplied by the distance to the ground (a displacement). If the ball is thrown upwards, the work done by the gravitational force is negative, and is equal to the weight multiplied by the dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
