equilibrium isotope effect SeeISOTOPE EFFECT.
equivalent The mass of acid required to provide one
mole of hydrogen ions in a reaction, or the mass of
base required to react with a mole of hydrogen ions.
equivalent weight (1) Acid, the mass that provides
one mole of H+. (2) Base, the mass that neutralizes one
mole of H+. (3) Reduction–oxidation reaction, the mass
of reactant that either gains or loses one mole of elec-
trons.
Erlanger, Joseph(1874–1965) AmericanNeurosci-
entist Joseph Erlanger was born on January 5, 1874,
in San Francisco, California, to Herman and Sarah
Erlanger. He received a B.S. in chemistry at the Univer-
sity of California and later attended Johns Hopkins
University to study medicine, receiving an M.D. in
- He was appointed assistant in the department of
physiology at the medical school after spending a year
of hospital training at Johns Hopkins Hospital until
1906, moving up successively as instructor, associate,
and associate professor. He was then appointed the
first professor of physiology in the newly established
Medical School of the University of Wisconsin. In
1910 he was appointed professor of physiology in the
reorganized Medical School of the Washington Univer-
sity in St. Louis, retiring in 1946 as chairman of the
school.
In 1922 in collaboration with his student Herbert
Gasser, Erlanger adapted the cathode-ray oscillograph
for studying nerve action potentials. They amplified the
electrical responses of a single nerve fiber and analyzed
them with the use of the oscilloscope. The characteris-
tic wave pattern of an impulse generated in a stimu-
lated nerve fiber could be observed on the screen and
the components of the nerve’s response studied.
Erlanger and Gasser were given the Nobel Prize for
medicine or physiology in 1944 for this work. Erlanger
later worked on the metabolism of dogs with shortened
intestines, on traumatic shock, and on the mechanism
of the production of sound in arteries.
With Gasser he wrote Electrical Signs of Nervous
Activity(1937). He died on December 5, 1965, in St
Louis, Missouri.
ESE(electron spin echo) See ELECTRON SPIN-ECHO
SPECTROSCOPY.ESEEM(electron spin-echo envelope modulation)
SeeELECTRON SPIN-ECHO SPECTROSCOPY.ESR(electron spin resonance) SeeELECTRON PARAM-
AGNETIC RESONANCE SPECTROSCOPY.ester Any organic compound produced through the
reaction of a carboxylic acid and alcohol that removes
the water from the compound. An example is ethyl
acetate.eta (η) symbol SeeHAPTO.ethanol Another word for ethyl alcohol, C 2 H 5 OH.ether A compound with an oxygen atom attached to
two hydrocarbon groups. Any carbon compound con-
taining the functional group C–O–C, such as diethyl
ether.ethylene(C 2 H 4 ) A reactive chemical made from nat-
ural gas or crude oil components (occurs naturally in
both petroleum and natural gas) that acts as a plant
hormone. The only gaseous hormone, it is used for
accelerating fruit ripening (bananas), maturing citrus
fruit color, leaf abscission, aging, and increasing the
growth rate of seedlings, vegetables, and fruit trees.ET-value See DIMROTH-REICHARDT ET PARAMETER;
Z-VALUE.euchromatin Within a nucleus of eukaryotes there
are two types of a mixture of nucleic acid and protein
called CHROMATIN that make up a CHROMOSOME:
euchromatin and heterochromatin. During interphase,
the genetically active euchromatin is uncoiled and is100 equilibrium isotope effect