state may have been reached either
as a result of a random Ûuctuation or
an external force (such as an electric
or magnetic Üeld) and that the evolution towards equilibrium is the same
in both cases (for a sufÜciently
small Ûuctuation). The Ûuctuation–
dissipation theorem enables *transport coefÜcients to be calculated in
terms of response to external Üelds.
Ûuidization A technique used in
some industrial processes in which
solid particles suspended in a stream
of gas are treated as if they were in
the liquid state. Fluidization is useful
for transporting powders, such as
coal dust. Fluidized beds, in which
solid particles are suspended in an
upward stream, are extensively used
in the chemical industry, particularly
in catalytic reactions where the powdered catalyst has a high surface
area. They are also used in furnaces,
being formed by burning coal in a
hot turbulent bed of sand or ash
through which air is passed. The bed
behaves like a Ûuid, enabling the
combustion temperature to be reduced so that the production of
polluting oxides of nitrogen is diminished. By adding limestone to the
bed with the fuel, the emission of
sulphur dioxide is reduced.
High-pressure Ûuidized beds are
also used in power-station furnaces
in a combined cycle in which the
products of combustion from the
Ûuidized bed are used to drive a gas
turbine, while a steam-tube boiler in
the Ûuid bed raises steam to drive a
steam turbine. This system both increases the efÜciency of the combustion process and reduces pollution.
Ûunitrazepam A *benzodiazepine
used medically in some countries as
a powerful hypnotic, sedative, and
muscle relaxant. It was marketed in
the US under the tradename Rohypnol. Flunitrazepam has become notorious as a so-called ‘date rape’ drug. It
is quickly eliminated from the body,
difÜcult to detect, and causes amnesia, so that victims cannot remember
events that occur when under the
inÛuence of the drug.
229
fluorine
f
N
N
N
H 2
C
H 3
O
F
Flunitrazepam
Ûuorescein A yellowish-red dye
that produces yellow solutions with a
green Ûuorescence. It is used in tracing water Ûow and as an *adsorption
indicator.
Ûuorescence See luminescence.
Ûuoridation The process of adding
very small amounts of Ûuorine salts
(e.g. sodium Ûuoride, NaF) to drinking water to prevent tooth decay. The
Ûuoride becomes incorporated into
the Ûuoroapatite (see apatite) of the
growing teeth and reduces the incidence of dental caries.
Ûuoride See halide.
Ûuorination A chemical reaction
in which a Ûuorine atom is introduced into a molecule. See halogenation.
Ûuorine Symbol F. A poisonous
pale yellow gaseous element belonging to group 17 (formerly VIIB) of the
periodic table (the *halogens); a.n. 9;
r.a.m. 18.9984; d. 1.7 g dm
–3
; m.p.
–219.62°C; b.p. –188.1°C. The main
mineral sources are *Ûuorite (CaF 2 )
www.AzShimi.ir www.AzShimi.com
as a result of a random Ûuctuation or
an external force (such as an electric
or magnetic Üeld) and that the evolution towards equilibrium is the same
in both cases (for a sufÜciently
small Ûuctuation). The Ûuctuation–
dissipation theorem enables *transport coefÜcients to be calculated in
terms of response to external Üelds.
Ûuidization A technique used in
some industrial processes in which
solid particles suspended in a stream
of gas are treated as if they were in
the liquid state. Fluidization is useful
for transporting powders, such as
coal dust. Fluidized beds, in which
solid particles are suspended in an
upward stream, are extensively used
in the chemical industry, particularly
in catalytic reactions where the powdered catalyst has a high surface
area. They are also used in furnaces,
being formed by burning coal in a
hot turbulent bed of sand or ash
through which air is passed. The bed
behaves like a Ûuid, enabling the
combustion temperature to be reduced so that the production of
polluting oxides of nitrogen is diminished. By adding limestone to the
bed with the fuel, the emission of
sulphur dioxide is reduced.
High-pressure Ûuidized beds are
also used in power-station furnaces
in a combined cycle in which the
products of combustion from the
Ûuidized bed are used to drive a gas
turbine, while a steam-tube boiler in
the Ûuid bed raises steam to drive a
steam turbine. This system both increases the efÜciency of the combustion process and reduces pollution.
Ûunitrazepam A *benzodiazepine
used medically in some countries as
a powerful hypnotic, sedative, and
muscle relaxant. It was marketed in
the US under the tradename Rohypnol. Flunitrazepam has become notorious as a so-called ‘date rape’ drug. It
is quickly eliminated from the body,
difÜcult to detect, and causes amnesia, so that victims cannot remember
events that occur when under the
inÛuence of the drug.
229
fluorine
f
N
N
N
H 2
C
H 3
O
F
Flunitrazepam
Ûuorescein A yellowish-red dye
that produces yellow solutions with a
green Ûuorescence. It is used in tracing water Ûow and as an *adsorption
indicator.
Ûuorescence See luminescence.
Ûuoridation The process of adding
very small amounts of Ûuorine salts
(e.g. sodium Ûuoride, NaF) to drinking water to prevent tooth decay. The
Ûuoride becomes incorporated into
the Ûuoroapatite (see apatite) of the
growing teeth and reduces the incidence of dental caries.
Ûuoride See halide.
Ûuorination A chemical reaction
in which a Ûuorine atom is introduced into a molecule. See halogenation.
Ûuorine Symbol F. A poisonous
pale yellow gaseous element belonging to group 17 (formerly VIIB) of the
periodic table (the *halogens); a.n. 9;
r.a.m. 18.9984; d. 1.7 g dm
–3
; m.p.
–219.62°C; b.p. –188.1°C. The main
mineral sources are *Ûuorite (CaF 2 )
www.AzShimi.ir www.AzShimi.com