Pathogenic microorganisms associated with Ready-to-Eat fresh-cut vegetables and referred to in the model may include Listeria monocytogenes, Salmonella. , Shigella. , Escherichia coli O157:H7, viruses (Hepatitis A virus, Norovirus, and Rota virus), and parasites (Cyclospora. and Cryptosporidium. ).
An isotope is a form of a chemical element whose atomic nucleus contains a specific number of neutron s, in addition to the number of proton s that uniquely defines the element.The nuclei of most atom s contain neutrons as well as protons.n atom of carbon-14 contains 6 protons and 8 neutrons and is denoted 14 C. Over time, 14 C decays into 12 C. Sometimes the isotope of an element is denoted by writing the nucleon number after the chemical symbol, and not as a superscript.
Isotopes are atoms of the same element (that is, with the same number of protons in their atomic nucleus), but having different numbers of neutrons. Most (66 of 94) naturally occurring elements have more than one stable isotope.Thus, for example, there are three main isotopes of carbon.he mass number of an element, A, is the number of nucleons (protons and neutrons) in the atomic nucleus. Different isotopes of a given element are distinguished by their mass numbers, which are conventionally written as a superscript on the left hand side of the atomic symbol (e.g., 238 U).