Radioactive tracer such as a cell or tissue, or as a flow tracer to track fluid flow. Radioactive tracers are also used to determine the location of fractures created by hydraulic fracturing in natural gas production. Radioactive tracers form the basis of a variety of imaging systems, such as, PET scans, SPECT scans and technetium scans. Radiocarbon dating uses the naturally occurring carbon-14 isotope as an isotopic label. Isotopes of a chemical element differ only in the mass number. For example, the isotopes of hydrogen can be written as H, H and H, with the mass number at top left. When the
Guar Guar The Guar or cluster bean, with the botanical name Cyamopsis tetragonoloba, is an annual legume and the source of guar gum. It is also known as Gavar, Guwar, or Guvar bean. The origin of "Cyamopsis tetragonoloba" is unknown, since it has never been found in the wild. It is assumed to have developed from the African species "Cyamopsis senegalensis". It was further domesticated in India and Pakistan, where it has been cultivated for many centuries. Guar grows well in semiarid areas, but frequent rainfall is necessary. This legume is a very valuable plant within a crop rotation cycle, as