Salehi stated that
Oxygen-18, a natural isotope of oxygen, which has its uses in the medical industry, will import currency to Iran.
Oxygen-18 is a natural, stable isotope of oxygen and is an important precursor for the production of fluorodeoxyglucose (FDG) used in positron emission tomography (PET).
During drought, oxygen-16, which is lighter than
oxygen-18, evaporates faster so that the remaining water in the lake and, consequently, the snails' shells, become enriched with
oxygen-18.
Relation between long-term trends of
oxygen-18 isotope composition of precipitation and climate.
The relative abundances of
oxygen-18 and carbon-13 are very sensitive to formation temperature.
Their topics include copper dioxygenases, energy conversion and conservation by cytochrome oxidases, the structure and reactivity of copper-oxygen species revealed by competitive
oxygen-18 isotope effects, chemical reactivity in copper active-oxygen complexes, supramolecular copper dioxygen chemistry, and organic synthetic methods using copper oxygen chemistry.
However, by taking advantage of the ability of SIMS to separate and measure isotopes, the photooxidation products can be labeled with a unique isotope of oxygen, allowing direct measurement of the photooxidation products (see Figure 7).(15,16) If the paint system is exposed to UV light in an atmosphere of
oxygen-18, then
oxygen-18 labeled photooxidation products will be created.
When an oxygen atom has 10 neutrons, or 18 total particles in its nucleus, it is called
oxygen-18. In general, when an atom has a different number of neutrons in its nucleus, it is called an isotope.
Scientists measure the amounts of two isotopes of oxygen in the shells, oxygen-16 and
oxygen-18. The ratio of these isotopes helps them reconstruct a variety of past conditions: seawater temperatures, evaporation, precipitation, river runoff, and the volume of water on Earth that took the form of ice frozen in ice sheets and glaciers, rather than liquid in lakes and oceans.
A conventional proxy for temperature is the ratio of the heavy isotope of oxygen,
Oxygen-18, to the most common form, Oxygen-16.
delta
oxygen-18 ([[delta].sup.18]O) = ([R.sub.sample] /[R.sub.standard] - 1) X 1,000, (1)