A soft, brown, nonmetallic chemical element; symbol B. → Atomic number 5; → atomic weight 10.81; → melting point about 2,300°C; → specific gravity 2.3 at 25°C; → valence +3. Boron occurs as borax and boric acid. It is used for hardening steel and for producing enamels and glasses. Since it absorbs slow neutrons, it is used in steel alloys for making control rods in nuclear reactors. Boron was separated in 1808 by Joseph Louis Gay Lussac (1778-1850) and Louis Jacques Thénard (1777-1857) and independently by Sir Humphry Davy (1778-1829).
From bor(ax), from M.Fr. boras, from M.L. borax, from Ar. buraq, from Pers. burah "borax, nitre, used in soldering gold" + (car)bon.
Bor, loan from Fr., as above.
Bose-Einstein condensate (BEC)
Fr.: condensat de Bose-Einstein
A state of matter in which a group of atoms or subatomic particles,
cooled to within → absolute zero,
coalesce into a single quantum mechanical entity
that can be described by a → wave function.
When a group of atoms are cooled down to very near
absolute zero, the atoms hardly move relative to each other, because
they have almost no free energy
to do so. Hence the atoms clump together and enter
the same → ground energy states.
They become identical and the whole group starts behaving as though it were a
single atom. A Bose-Einstein condensate results from a
→ quantum transition phase
called the → Bose-Einstein condensation.
This form of matter was predicted in 1924 by Albert Einstein on
the basis of the quantum formulations of the Indian physicist
Satyendra Nath Bose.
Bose-Einstein condensation (BEC)
Fr.: condensation de Bose-Einstein
A → quantum phase transition during which the → bosons constituting a sufficiently cooled boson gas are all clustered in the → ground energy state. The phase transition results in a → Bose-Einstein condensate. This phenomenon occurs when the temperature becomes smaller than a critical value given by: Tc = (2πħ2 / km)(n / 2.612)2/3, where m is mass of each boson, ħ is the → reduced Planck's constant, k is → Boltzmann's constant, and n is the particle number density. When T ≤ Tc, the → de Broglie wavelength of bosons becomes comparable to the distance between bosons.
Fr.: distribution de Bose-Einstein
âmâr-e Bose-Einstein (#)
Fr.: statistique de Bose-Einstein
Same as → Bose-Einstein distribution.
Any of a class of particles (such as the → photon, → pion, or → alpha particle) that have zero or integral → spin and do not obey the → Pauli exclusion principle. The energy distribution of bosons is described by → Bose-Einstein statistics. See also: → gauge boson, → Higgs boson, → W boson, → Z boson, → intermediate boson.
Boson, in honor of the Indian-American physicist Satyendra Nath Bose (1894-1974).
From botanic, from Fr. botanique, M.L. botanicus, from Gk. botanikos "of herbs," from botane "herb, grass, pasture."
Botein (δ Ari)
Botein, from Ar. Al-Butain "the little belly."
Boteyn, from Ar. Al-Butain.
From O.Fr. bo(u)teille, from L.L. butticula diminutive of L. buttis "a cask."
Botri, loan from Fr. bouteille or E. bottle, as above.
tah (#), pâyin (#)
Fr.: bas, fond
M.E. botme; O.E. botm, bodan "ground, soil, lowest part" (cf. O.Fris. boden "soil," O.N. botn, O.H.G. bodam, Ger. Boden "ground, earth, soil"), akin to Pers. bon "basis; root; foundation; bottom;" Mid.Pers. bun "root; foundation; beginning;" Av. būna- "base, depth" (Skt. bundha-, budhná- "base, bottom," Pali bunda- "root of tree;" Gk. pythmen "foundation;" L. fundus "bottom, piece of land, farm," O.Ir. bond "sole of the foot").
Tah "bottom; end"
(Mid.Pers. tah "bottom." The origin of this term is not clear.
It may be related to PIE *tenegos "water bottom;" cf.
Gk. tenagos "bottom, swamp," Latvian tigas, from *tingas, from
bottom-up structure formation
diseš-e sâxtâr az pâyin bé bâlâ
Fr.: formation des structures du bas vers le haut
1) bandidé; 2) karân
Fr.: lié; lien
Fr.: charge liée
Any electric charge which is bound to an atom or molecule, in contrast to free charge, such as metallic conduction electrons, which is not. Also known as → polarization charge.
Fr.: amas lié
A cluster of astronomical objects, such as stars or galaxies, held together by their mutual gravitational attraction. → bound system.
Fr.: occurrence liée
Fr.: orbite liée
The orbit described by an object around a central gravitational force in a system whose total energy is negative. An elliptical orbit.
Fr.: système lié
A system composed of several material bodies the total energy of which (the sum of kinetic and potential energies) is negative, e.g. a → bound cluster.
Fr.: transition liée-liée
Fr.: transition liée-libre
Fr.: limite, bord
Something that indicates a border or limit; the border or limit so indicated.
From Fr., from O.Fr. bodne, from M.L. bodina, butina "boundary, boundary marker."
Karân, karâné, kenâr from Mid.Pers. karânag, Av. karana- "boundary."