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The atomic mass constant, denoted m u, is defined identically, giving m u = 1 / 12 m(12 C) = 1 Da. [ 3 ] This unit is commonly used in physics and chemistry to express the mass of atomic-scale objects, such as atoms , molecules , and elementary particles , both for discrete instances and multiple types of ensemble averages.
The enzyme unit, or international unit for enzyme (symbol U, sometimes also IU) is a unit of enzyme's catalytic activity. [1]1 U (μmol/min) is defined as the amount of the enzyme that catalyzes the conversion of one micro mole of substrate per minute under the specified conditions of the assay method.
Rack with sample component sizes including an A/V half-rack unit. A rack unit (abbreviated U or RU) is a unit of measure defined as 1 + 3 ⁄ 4 inches (44.45 mm). [1] [2] It is most frequently used as a measurement of the overall height of 19-inch and 23-inch rack frames, as well as the height of equipment that mounts in these frames, whereby the height of the frame or equipment is expressed ...
One dalton is equal to 1 ⁄ 12 the mass of a carbon-12 atom in its natural state. Thus, the numeric value of the atomic mass when expressed in daltons has nearly the same value as the mass number . The value of 1 unified atomic mass unit in kilograms is m u = 1.660539066 × 10 − 27 k g {\displaystyle m_{\rm {u}}=1.660539066\times 10^{-27 ...
Hartree defined units based on three physical constants: [1]: 91 Both in order to eliminate various universal constants from the equations and also to avoid high powers of 10 in numerical work, it is convenient to express quantities in terms of units, which may be called 'atomic units', defined as follows:
Theoretical isotope distribution for the molecular ion of caffeine. The molecular mass (abbreviated M r) of a substance, formerly also called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of 12 C).
One therm is equal to about 1,055 megajoules. Common units for selling by volume are cubic metre or cubic feet. Natural gas in the US is sold in therms or 100 cubic feet (100 ft 3). In Australia, natural gas is sold in cubic metres. One cubic metre contains about 38 megajoules. In most of the world, natural gas is sold in gigajoules.
The US fluid ounce is based on the US gallon, which in turn is based on the wine gallon of 231 cubic inches that was used in the United Kingdom prior to 1824. With the adoption of the international inch, the US fluid ounce became 1 ⁄ 128 gal × 231 in 3 /gal × (2.54 cm/in) 3 = 29.5735295625 mL exactly, or about 4% larger than the imperial unit.