lipoxygenase A nonHEME iron ENZYME that cat-
alyzes the INSERTIONof O 2 into polyunsaturated fatty
acids to form hydroperoxy DERIVATIVEs.
liquefaction When a solid begins to act as a fluid.
liquid aerosol A colloidal suspension of liquid in
gas.
liquid crystal An organic molecule that has crystal-
like properties but is liquid at normal temperatures.
liquid drop model (of the nucleus) States that
NUCLEONs interact strongly with each other, just like
molecules in a drop of liquid, which allows scientists to
correlate many facts about nuclear masses and energies,
as well as providing a useful model for understanding a
large class of nuclear reactions, including fission.
littoral zone The shallow shoreward region of a
freshwater body, just beyond the breaker zone, where
light penetrates to the bottom sediments, giving rise to
a zone that is colonized by rooted plants called helo-
phytes; a region of a lake or pond where the water is
less than 6 meters deep; in oceanography, the line
extending from the high-water line to about 200
meters; also called the intertidal zone where submer-
sion of tides is a normal event. The near-surface open
water surrounded by the littoral zone is the limnetic
zone, which gets ample light and is dominated by
plankton. The littoral system is divided into a eulittoral
(lower, middle, and upper) zone and a sublittoral (sub-
tidal or supratidal) zone, the zone exposed to air only
at its upper limit by the lowest spring tides. They are
separated at a depth of about 50 meters. The term is
also frequently used interchangeably with intertidal
zone.
Loewi, Otto(1873–1961) Austrian/American Physi-
cian, pharmacologist Otto Loewi was born on June
3, 1873, in Frankfurt-am-Main, Germany, to Jacob
Loewi, a merchant, and Anna Willstätter. He
attended the humanistic gymnasium (grammar
school) locally in 1881–90 and entered the Universi-
ties of Munich and Strassburg as a medical student
in 1891. In 1896 he received a doctor’s degree at
Strassburg University.
After spending a few months working in the bio-
chemical institute of Franz Hofmeister in Strassburg,
he became an assistant to Carl von Noorden, clinician
at the city hospital in Frankfurt during 1897–98. In
1898 he became an assistant of Professor Hans Horst
Meyer, a renowned pharmacologist at the University
of Marburg-an-der-Lahn, and professor of pharmacol-
ogy in Vienna. In 1905 Loewi became associate pro-
fessor at Meyer’s laboratory, and in 1909 he was
appointed to the chair of pharmacology in Graz. In
1940 he moved to the United States and became
research professor at the School of Medicine of New
York University, New York City, where he remained
until his death.
His neurological researches during the period
1921–26 provided the first proof that chemicals were
involved in the transmission of impulses from one
nerve cell to another and from neuron to the responsive
organ. It was for his discovery of the chemical trans-
mission of nerve impulses that he received the Nobel
Prize in physiology or medicine in 1936, jointly with
Sir Henry Dale. Loewi spent his years investigating the
physiology and pharmacology of metabolism, the kid-
neys, the heart, and the nervous system. He became an
American citizen in 1946 and died on December 25,
1961.London forces Attractive forces between apolar
molecules due to their mutual polarizability. They are
also components of the forces between POLAR
MOLECULEs. Also called dispersion forces.
See alsoVAN DERWAALS FORCES.lone (electron) pair Two paired electrons localized
in the valence shell on a single atom. Lone pairs should
be designated with two dots. The term nonbonding
electron pairis more appropriate and is found in many
modern textbooks.loose ion pair SeeION PAIR.168 lipoxygenase