Reduction can occur in the range of
temperatures in which the carbon
curve is lower than the metal curve.
The diagram was devised by the
physical chemist H. J. T. Ellingham.
elliptical polarization See polarization of light.
elongation (in protein synthesis)
The phase in which amino acids are
linked together by sequentially
formed peptide bonds to form a
polypeptide chain. Elongation factors
are proteins that – by binding to a
tRNA–amino-acid complex – enable
the correct positioning of this complex on the ribosome, so that translation can proceed.
eluate See chromatography; elution.
eluent See chromatography; elution.
elution The process of removing an
adsorbed material (adsorbate) from
an adsorbent by washing it in a liquid (eluent). The solution consisting
of the adsorbate dissolved in the eluent is the eluate. Elution is the
process used to wash components of
a mixture through a *chromatography column.
elutriation The process of suspending Ünely divided particles in an upward Ûowing stream of air or water
to wash and separate them into sized
fractions.
emanation The former name for
the gas radon, of which there are
three isotopes: Rn–222 (radium emanation), Rn–220 (thoron emanation),
and Rn–219 (actinium emanation).
emerald The green gem variety of
*beryl: one of the most highly prized
gemstones. The Ünest specimens
occur in the Muzo mines, Colombia.
Other occurrences include the Ural
Mountains, the Transvaal in South
Africa, and Kaligunan in India. Emeralds can also be successfully synthesized.
emergency action code See
hazchem code.
emery A rock composed of corundum (natural aluminium oxide,
Al 2 O 3 ) with magnetite, haematite, or
spinel. It occurs on the island of
Naxos (Greece) and in Turkey. Emery
is used as an abrasive and polishing
material and in the manufacture of
certain concrete Ûoors.
e.m.f. See electromotive force.
emission spectrum See spectrum.
empirical Denoting a result that is
obtained by experiment or observation rather than from theory.
empirical formula See formula.
emulsiÜcation (in digestion) The
breakdown of fat globules in the duodenum into tiny droplets, which provides a larger surface area on which
the enzyme pancreatic *lipase can
act to digest the fats into fatty acids
and glycerol. EmulsiÜcation is assisted by the action of the bile salts
in bile.
emulsion A *colloid in which small
particles of one liquid are dispersed
in another liquid. Usually emulsions
involve a dispersion of water in an
oil or a dispersion of oil in water, and
are stabilized by an emulsiÜer. Commonly emulsiÜers are substances,
such as *detergents, that have
lyophobic and lyophilic parts in their
molecules.
en The symbol for ethylene diamine
(1,2-diaminoethane) functioning as a
bidentate ligand, used in formulae.
enamine A type of compound with
the general formula
R
1 R
2 C = C(R
3
)–NR
4 R
5 ,
203
enamine
e
www.AzShimi.ir www.AzShimi.com
temperatures in which the carbon
curve is lower than the metal curve.
The diagram was devised by the
physical chemist H. J. T. Ellingham.
elliptical polarization See polarization of light.
elongation (in protein synthesis)
The phase in which amino acids are
linked together by sequentially
formed peptide bonds to form a
polypeptide chain. Elongation factors
are proteins that – by binding to a
tRNA–amino-acid complex – enable
the correct positioning of this complex on the ribosome, so that translation can proceed.
eluate See chromatography; elution.
eluent See chromatography; elution.
elution The process of removing an
adsorbed material (adsorbate) from
an adsorbent by washing it in a liquid (eluent). The solution consisting
of the adsorbate dissolved in the eluent is the eluate. Elution is the
process used to wash components of
a mixture through a *chromatography column.
elutriation The process of suspending Ünely divided particles in an upward Ûowing stream of air or water
to wash and separate them into sized
fractions.
emanation The former name for
the gas radon, of which there are
three isotopes: Rn–222 (radium emanation), Rn–220 (thoron emanation),
and Rn–219 (actinium emanation).
emerald The green gem variety of
*beryl: one of the most highly prized
gemstones. The Ünest specimens
occur in the Muzo mines, Colombia.
Other occurrences include the Ural
Mountains, the Transvaal in South
Africa, and Kaligunan in India. Emeralds can also be successfully synthesized.
emergency action code See
hazchem code.
emery A rock composed of corundum (natural aluminium oxide,
Al 2 O 3 ) with magnetite, haematite, or
spinel. It occurs on the island of
Naxos (Greece) and in Turkey. Emery
is used as an abrasive and polishing
material and in the manufacture of
certain concrete Ûoors.
e.m.f. See electromotive force.
emission spectrum See spectrum.
empirical Denoting a result that is
obtained by experiment or observation rather than from theory.
empirical formula See formula.
emulsiÜcation (in digestion) The
breakdown of fat globules in the duodenum into tiny droplets, which provides a larger surface area on which
the enzyme pancreatic *lipase can
act to digest the fats into fatty acids
and glycerol. EmulsiÜcation is assisted by the action of the bile salts
in bile.
emulsion A *colloid in which small
particles of one liquid are dispersed
in another liquid. Usually emulsions
involve a dispersion of water in an
oil or a dispersion of oil in water, and
are stabilized by an emulsiÜer. Commonly emulsiÜers are substances,
such as *detergents, that have
lyophobic and lyophilic parts in their
molecules.
en The symbol for ethylene diamine
(1,2-diaminoethane) functioning as a
bidentate ligand, used in formulae.
enamine A type of compound with
the general formula
R
1 R
2 C = C(R
3
)–NR
4 R
5 ,
203
enamine
e
www.AzShimi.ir www.AzShimi.com