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
Water gel explosive alcohol, guar gum, dextran gums, and urea-formaldehyde resins are the typical gelling agents. Guar, specifically, is a gelling agent used for the aqueous portion of the water gel explosives. The primary component of water gels is monomethylamine nitrate. Monomethylamine nitrate is made from monomethyl amine (MMA) and nitric acid. Water gel explosives are also made of ammonium nitrate, calcium nitrate, aluminum, ethylene glycol and TNT. The proportions of these components vary depending on the desired explosiveness of the water gel. Water gel explosives are produced by combining nitroparaffins, usually nitromethane, with an aqueous salt solution and a gelling agent. These