Negative refractionNegative refraction is the electromagnetic phenomenon where light rays become refracted at an interface that is opposite to their more commonly observed positive refractive properties. Negative refraction can be obtained by using a metamaterial which has been designed to achieve a negative value for (electric) permittivity (ε) and (magnetic) permeability (μ); in such cases the material can be assigned a negative refractive index. Such materials are sometimes called "double negative" materials.
Sandwich-structured compositeIn materials science, a sandwich-structured composite is a special class of composite materials that is fabricated by attaching two thin-but-stiff skins to a lightweight but thick core. The core material is normally low strength, but its higher thickness provides the sandwich composite with high bending stiffness with overall low density. Open- and closed-cell-structured foams like polyethersulfone, polyvinylchloride, polyurethane, polyethylene or polystyrene foams, balsa wood, syntactic foams, and honeycombs are commonly used core materials.
Feature filmA feature film or feature-length film (often abbreviated to feature) is a narrative film (motion picture or "movie") with a running time long enough to be considered the principal or sole presentation in a commercial entertainment program. The term feature film originally referred to the main, full-length film in a cinema program that included a short film and often a newsreel. Matinee programs, especially in the US and Canada, in general, also included cartoons, at least one weekly serial and, typically, a second feature-length film on weekends.
Honeycomb structureHoneycomb structures are natural or man-made structures that have the geometry of a honeycomb to allow the minimization of the amount of used material to reach minimal weight and minimal material cost. The geometry of honeycomb structures can vary widely but the common feature of all such structures is an array of hollow cells formed between thin vertical walls. The cells are often columnar and hexagonal in shape. A honeycomb shaped structure provides a material with minimal density and relative high out-of-plane compression properties and out-of-plane shear properties.
Competitive inhibitionCompetitive inhibition is interruption of a chemical pathway owing to one chemical substance inhibiting the effect of another by competing with it for binding or bonding. Any metabolic or chemical messenger system can potentially be affected by this principle, but several classes of competitive inhibition are especially important in biochemistry and medicine, including the competitive form of enzyme inhibition, the competitive form of receptor antagonism, the competitive form of antimetabolite activity, and the competitive form of poisoning (which can include any of the aforementioned types).
AnisotropyAnisotropy (ˌaenaɪˈsɒtrəpi,_ˌænɪ-) is the structural property of non-uniformity in different directions, as opposed to isotropy. An anisotropic object or pattern has properties that differ according to direction of measurement. For example many materials exhibit very different properties when measured along different axes: physical or mechanical properties (absorbance, refractive index, conductivity, tensile strength, etc.). An example of anisotropy is light coming through a polarizer.
Silent filmA silent film is a film with no synchronized recorded sound (or more generally, no audible dialogue). Though silent films convey narrative and emotion visually, various plot elements (such as a setting or era) or key lines of dialogue may, when necessary, be conveyed by the use of inter-title cards. The term "silent film" is something of a misnomer, as these films were almost always accompanied by live sounds. During the silent era that existed from the mid-1890s to the late 1920s, a pianist, theater organist—or even, in large cities, a small orchestra—would often play music to accompany the films.
Short filmA short film is any motion picture that is short enough in running time not to be considered a feature film. The Academy of Motion Picture Arts and Sciences defines a short film as "an original motion picture that has a running time of 40 minutes or less, including all credits". In the United States, short films were generally termed short subjects from the 1920s into the 1970s when confined to two 35 mm reels or less, and featurettes for a film of three or four reels. "Short" was an abbreviation for either term.
Diffraction gratingIn optics, a diffraction grating is an optical grating with a periodic structure that diffracts light into several beams travelling in different directions (i.e., different diffraction angles). The emerging coloration is a form of structural coloration. The directions or diffraction angles of these beams depend on the wave (light) incident angle to the diffraction grating, the spacing or distance between adjacent diffracting elements (e.g., parallel slits for a transmission grating) on the grating, and the wavelength of the incident light.
Aggregate (composite)Aggregate is the component of a composite material that resists compressive stress and provides bulk to the composite material. For efficient filling, aggregate should be much smaller than the finished item, but have a wide variety of sizes. For example, the particles of stone used to make concrete typically include both sand and gravel. Aggregate composites tend to be much easier to fabricate, and much more predictable in their finished properties, than fiber composites.
