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
Xanthan gum gum as a laxative. As described above, xanthan gum binds water very efficiently, which significantly aids passing stools. Some people react to much smaller amounts of xanthan gum with symptoms of intestinal bloating and diarrhea. There are many substitutes for xanthan gum when used for baking such as guar gum and locust bean gum. Xanthan gum is produced by the fermentation of glucose, sucrose, or lactose. The polysaccharide is prepared by the bacteria being inoculated into a sterile aqueous solution of carbohydrate(s), a source of nitrogen, dipotassium phosphate, and some trace elements. The medium is well-aerated and stirred, and the