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          dalton (Da or D)an alternate name for the unified atomic mass unit (u or amu). The dalton is often used in microbiology and biochemistry to state 
            the masses of large organic molecules; these measurements are typically in 
            kilodaltons (kDa). It seems necessary to have such a unit, since "kilo-amu" 
            would be such a clumsy name. The SI accepts the dalton 
            as an alternate name for the unified atomic mass unit and specifies Da as 
            its proper symbol. The unit honors the English chemist John Dalton (1766-1844), 
            who proposed the atomic theory of matter in 1803.damsymbol for the dekameter (10 meters; see entry below), a metric unit of 
            distance.dana traditional Chinese weight unit, previously spelled tan in many 
            English works. During the European colonial era the unit was equal to 100 catties or 133.333 pounds. 
            In modern China the dan is equal to 100 jin, 
            which is exactly 50 kilograms (110.231 pounds). The dan is the Chinese equivalent 
            of the European quintal or hundredweight.daNsymbol for the decanewton or dekanewton (see below under dekanewton), a 
            common metric unit of force.Danjon scalea scale measuring the brightness (or rather, the darkness) of lunar eclipses, 
            devised by the French astronomer André Louis Danjon (1890-1967). Wikipedia has a description of the scale.darafa unit of electrical elastance, which is the ability of an electric potential 
            to charge a capacitor. The daraf is equal to one volt of potential per coulomb 
            of charge (V/C). The name of the unit is "farad" spelled backwards, because 
            the elastance, in darafs, is 1 divided by the capacitance in farads. This 
            unit is not recognized as part of the SI.darcya CGS unit of permeability. Permeability is the 
            extent to which a solid allows the flow of a fluid. This flow depends on the 
            properties of the solid and also on the dynamic viscosity of the fluid and 
            the difference in pressure driving the flow. One darcy is the permeability 
            of a solid through which one cubic centimeter of fluid, having a viscosity 
            of one centipoise, will flow in one second 
            through a section one centimeter thick and one square centimeter in cross 
            section, if the pressure difference between the two sides of the solid is 
            one atmosphere. It turns out that permeability 
            has the same units as area; since there is no SI unit 
            of permeability, square meters are used. One darcy is equal to about 0.98692 
            x 10-12 square meter. The unit is named for a French scientist, 
            H. Darcy (1803-1858), who did pioneering work in the study of permeability. | 
           John Dalton (1766-1844)
 English chemist and physicist
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