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Abstract: Microwave activation, as a
non-conventional energy source, has received
considerable attention in various fields in addition to
being used for heating or cooking food. Microwaves are
being used for diagnosis of various diseases such as
diabetes mellitus, dental diagnosis, as well as in the
diagnosis and treatment of cancers. Microwave based
hyperthermia technique (thermotherapy) has been used for
the treatment of patients suffering from prostate and
breast cancer where intense microwave generated heat is
used to destroy cancerous tissue. Small molecules can be
synthesized rapidly due to which this technique has
gained wide acceptance as a valuable tool for
accelerating drug discovery and development processes.
In addition microwaves are also used for drying of
fruits, vegetables, flowers, wood, herbs, etc.
disinfection of biomedical waste, decrease air
pollutants, remediation of soil, and extraction of
active constituents. This article enlists various
medicinal, pharmaceutical and other applications of
microwaves.
Introduction: Microwave activation, as a
non-conventional energy source, has received
considerable attention in various fields in addition to
being used for heating or cooking food. This is mainly
because of increasing need for automation and
environment friendliness, and in order to increase
productivity, safety and quality with highly improved
efficiency.1 By “microwaves” we mean the range of radio
frequencies between about 300 MHz (one megahertz is one
million oscillations per second, one GHz is 1,000 MHz)
and about 30 GHz (one gigahertz, or one billion
oscillations per second). Although there is no formal
definition of the frequency range for “microwaves”, some
text books will say all frequencies above 300 MHz as
microwaves. People often misuse the term “millimeter
waves” to mean any microwaves of higher frequencies than
those normally used. Millimeter waves range between 30
GHz to 300 GHz and above 300 GHz waves are considered as
“sub-millimeter waves”. Most common applications are
within the 1 to 40 GHz range. Microwave frequency bands,
as defined by the Radio Society of Great Britain (RSGB)
have been explained in Table 1. Wavelengths in the range
1 to 25 centimeter are extensively used for RADAR
transmissions and the remaining range is used for
telecommunications. In order to avoid interference, the
domestic and industrial microwave-ovens are required to
operate at either 12.2cm (2.45 GHz) or 33.3cm (0.9 GHz)
unless the apparatus is shielded in such a way that no
radiation losses occur. Microwaves are very short radio
waves that travel in an invisible circular motion
through the air. Microwaves go faster than television
waves but slower than infrared rays. They are stronger
than radio frequency waves, but weaker than X-rays. They
can pass through glass, ceramic, paper plastic and
similar materials. They are reflected by metal, aluminum
foil and absorbed by food.
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