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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A linear polymer of (1→4)-linked β-<small>D</small>-glucopyranosyl units, and the most abundant of all naturally occurring substances. Cellulose constitutes approximately a third of all vegetable matter and thus it exists in far greater quantity than any other polysaccharide. It occurs as a principal structural component of the cell walls of mosses and seaweeds (25–30%), annual plants (25–35%), and trees (40–50%); cotton fiber contains 98% cellulose along with 1% protein, 0.65% pectic substance, and 0.15% mineral matter. Cellulose also is produced by some microorganisms, in a few cases reaching amounts of 20–30%.
Industry:Science
A linear structural member supported both transversely and rotationally at one end only; the other end of the member is free to deflect and rotate. Cantilevers are common throughout nature and engineered structures; examples are a bird's wing, an airplane wing, a roof overhang, and a balcony.
Industry:Science
A linear, homogeneous partial differential equation that determines the evolution with time of a quantum-mechanical wave function.
Industry:Science
A linear, passive, two-port electric circuit element whose transmission properties are such that it is effectively a half wavelength longer for one direction of transmission than for the other direction of transmission. Thus a gyrator is a device that causes a reversal of signal polarity for one direction of propagation but not for the other. (A two-port element has a pair of input terminals and a pair of output terminals.) This device is novel, since it violates the theorem of reciprocity.
Industry:Science
A link in several kinds of mechanisms. Usually one end of a connecting rod is intended to follow a circular path, while the other end follows a path along a straight line or a curve of large radius. The term is sometimes applied, however, to any straight link that transmits motion or power from one linkage to another within a mechanism. <b>Figure 1</b> shows conventional arrangements of connecting rods in typical mechanisms. In some applications (for example, the connecting rod between the crank and an overhead oscillating member or walking beam in a well-drilling rig, or between the steering column and cross-links in an automobile) the connecting rod is called a pitman.
Industry:Science
A linkage that transmits rotation between two shafts whose axes are coplanar but not coinciding. The universal joint is used in almost every class of machinery: machine tools, instruments, control devices, and, most familiarly, automobiles.
Industry:Science
A lipid that contains one or more phosphate groups. Like fatty acids, phospholipids are amphipathic in nature; that is, each molecule consists of a hydrophilic (having strong affinity for water) portion and a hydrophobic (lacking affinity for water) portion. Due to the amphipathic nature and insolubility in water, phospholipids are ideal compounds for forming biological membranes. Phospholipids are present in plasma lipoproteins, egg yolk, soya bean, and animal tissues such as brain. Commercially, phospholipids are used to make chocolates, caramels, and many other prepared foods. They are important components in cosmetics and are also used as solubilizing and texturizing agents in pharmaceutical preparations. Medically, phospholipids are used to form therapeutic liposomes—microscopic spheres enclosed by phospholipid membranes and containing specific drugs for delivery into the body. The phospholipid sphere fuses with the plasma membrane of the target cell, and the drug inside the liposome is emptied into the cell. Some liposomes are preferentially recognized by certain organs in the body, thus facilitating the targeted delivery of drugs.
Industry:Science
A list of chemical elements arranged along horizontal rows in increasing atomic number. It is organized such that the vertical columns consist of elements with remarkably similar properties. The first column, known as the alkali metals (albeit with hydrogen, a nonmetal on top), contains elements with just one outer (valence) electron. The last column has completely filled valence orbitals leading to chemically inert elements called the noble gases. The position of elements in the periodic table provides a powerful method of classifying not only the physical properties of elements but also their expected properties in molecules and solids.
Industry:Science
A lithium aluminum phosphate mineral of basic formula LiAl(PO<sub>4</sub>)(F). The structure of amblygonite consists of phosphate (PO<sub>4</sub>) groups of tetrahedra and AlO<sub>6</sub> groups of octahedra. Each PO<sub>4</sub> tetrahedron is connected to an AlO<sub>6</sub> octahedron. Corner-sharing octahedra form zig-zag chains along the b axis. Lithium (Li) is in fivefold coordination, and lies between the PO<sub>4</sub> tetrahedra and nearest AlO<sub>6</sub> octahedra. The dominant substitution in this mineral structure is hydroxyl (OH) for fluorine (F). This substitution gives rise to the amblygonite-montebrasite (LiAlPO<sub>4</sub>(OH)) solid solution series. When OH is greater than F, the mineral is known as montebrasite. Appreciable amounts of sodium substitute for lithium in the five-coordinated polyhedra. The sodium-rich varieties such as natromontebrasite and hedronite are rare.
Industry:Science
A little-studied group of ciliates comprising an order of the Holotrichia. The majority occur as commensals on marine crustaceans. This association is generally more intimate and complex than that of the chonotrichs found on related hosts. Their life histories may become exceedingly complicated, and they appear to bear a direct relationship to the molting cycles of their hosts. Apostomes are particularly characterized by the presence of a unique rosette in the vicinity of an inconspicuous mouth opening and the possession of only a small number of ciliary rows wound around the body in a spiral fashion. <i>Foettingeria</i> (see <b>illus.</b>) is an example commonly encountered.
Industry:Science
