atomic mass unit


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Related to atomic mass unit: relative atomic mass, atomic weight

unit

 [u´nit]
1. a single thing; one segment of a whole that is made up of identical or similar segments.
2. a specifically defined amount of anything subject to measurement, as of activity, dimension, velocity, volume, or the like.
3. a distinct part of a hospital, usually having a specific physical location and serving a defined function; see under names of specific units.
Ångström unit angstrom.
atomic mass unit (u) (amu) the unit of mass equal to ¹⁄₁₂ the mass of the nuclide of carbon 12. Called also dalton.
autonomous nursing unit a nursing unit under a decentralized administration system in which the staff is responsible for all aspects of unit functioning.
British thermal unit (BTU) a unit of heat formerly widely used, being the amount necessary to raise the temperature of 1 pound of water from 39° to 40°F., equal to approximately 252 calories.
CH50 unit the amount of complement that will lyse 50 per cent of a standard preparation of sheep red blood cells coated with antisheep erythrocyte antibody.
continuing education unit (CEU) a unit of credit for educational offerings given to professional persons, determined by a professional organization according to a mathematical formula after a thorough review of the program of study, the qualifications of the instructors, and the program objectives.
critical care unit intensive care unit.
electrostatic u's (esu) that system of units that is based on the fundamental definition of a unit charge as one that will repel a similar charge with a force of 1 dyne when the two charges are 1 cm apart in a vacuum.
environmental control unit a computerized system that allows the handicapped individual to operate several different appliances using a keyboard or other input device.
heat unit the amount of heat energy that is produced by one kVp (kilovolt peak) and one mA (milliampere) for one second with single phase, full wave rectified radiographic equipment.
Hounsfield unit an arbitrary unit of x-ray attenuation used for CT scans. Each voxel is assigned a value on a scale in which air has a value of −1000; water, 0; and compact bone, +1000.
intensive care unit see intensive care unit.
International unit (IU)
1. a unit of enzyme activity equal to the amount of enzyme that catalyzes the conversion of one micromole of substrate or coenzyme per minute under specified conditions (temperature, pH, and substrate concentration) of the assay method. Abbreviated U.
2. any of several arbitrary units that have been adopted by international bodies to express the quantities of certain vitamins (A, C, D, and thiamine hydrochloride), hormones (androgen, chorionic gonadotropin, estradiol benzoate, estrone, insulin, progesterone, and prolactin), and drugs (digitalis and penicillin).
Kienböck's unit a unit of x-ray exposure equal to 0.1 erythema dose; symbol X.
motor unit the unit of motor activity formed by a motor nerve cell and its many innervated muscle fibers.
postanesthesia care unit (PACU) a specialty unit in a hospital for giving postanesthesia care (care of patients recovering from anesthesia and intravenous sedation); formerly called recovery room.
radiologic u's units used to measure radiation, including roentgens, rads, rems, and curies.
u's of service (UOS)
1. the number of procedures done by a department.
2. individuals or groups of individuals who are the recipients of nursing care.
short procedures unit (short term care unit) a nursing unit where patients are briefly cared for following a medical or surgical procedure and are then discharged without spending the night.
SI unit any unit of the International System of units (the metric system); see also si units.
step-down unit a nursing unit designated to provide care for patients who are stable enough to be discharged from the intensive care unit but are not yet ready to be cared for on a medical-surgical unit.
Svedberg unit (S) a unit equal to 10−13 second used for expressing sedimentation coefficients of macromolecules.
Svedberg flotation unit (Sf) a unit equal to 10−13 second used for expressing negative sedimentation coefficients of macromolecules that float rather than sink in a centrifuge, e.g., lipoproteins.
terminal respiratory unit the functional unit of the lung, including a respiratory bronchiole, alveolar ducts and sacs, and alveoli; called also primary lobule of lung and primary respiratory lobule.
USP unit one used in the United States Pharmacopeia for expressing potency of drugs and other preparations.

a·tom·ic mass u·nit (amu),

a unit of mass equal by definition to 1/12 of the mass of an atom of carbon-12, which equals 1.6605402 × 10-27 kg; in terms of energy, 1 amu equals 931.49432 MeV. Compare: dalton.

atomic mass unit (amu)

[ətom′ik]
the mass of a neutral atom of an element, expressed as 112 of the mass of the isotope carbon-12, which has a value of exactly 12. The energy equivalent of 1 amu is 931.2 MeV. The mass equivalent of 1 amu is 1.66 (10-24 g).

atomic mass unit

A unit in mass spectrometry that represents the relative scale, in which the mass of 1H is given an integral value of 1, 12C is 12, and so on. The amu is an older unit, and has been replaced by the unified atomic mass unit.

a·tom·ic mass unit

(amu) (ă-tom'ik mas yū'nit)
A unit of mass by definition equal to 11/2 of the mass of an atom of carbon 12, which equals 1.6605402 × 10-27 kg; in terms of energy, 1 amu equals 931.49432 MeV.
Compare: dalton

unit

1. a single thing; one segment of a whole that is made up of identical or similar segments.
2. a specifically defined amount of anything subject to measurement, as of activity, dimension, velocity, volume, or the like.

Angstrom unit
atomic mass unit
see dalton.
International unit
1. see si units.
2. a unit of enzyme activity equal to the amount of enzyme that catalyzes the conversion of one micromole of substrate or coenzyme per minute under specified conditions (temperature, pH and substrate concentration) of the assay method. Abbreviated U.
3. any of several arbitrary units that have been adopted by international bodies to express the quantities of certain vitamins (A, C, D and thiamin hydrochloride), hormones (androgen, chorionic gonadotropin, estradiol benzoate, estrone, insulin, progesterone and prolactin), and drugs (digitalis and penicillin).
SI unit
any unit of the International System of units (the metric system). See si units.