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Nuclear Fuels, Nuclear Structure, the Mass Defect, and Radioactive Decay
Published in Robert E. Masterson, Introduction to Nuclear Reactor Physics, 2017
The constant of proportionality that expresses the relationship between the number of atoms you start with and the number of atoms that decay is called the radioactive decay constant. The radioactive decay constant has the units of inverse seconds (s−1), or inverse time. Each element and its isotopes has a different radioactive decay constant. The radioactive decay constant is usually referred to in scientific literature by the symbol λ (lambda). The radioactive decay constant has the units of inverse seconds, or more generally, inverse time. If you are familiar with college math or calculus, you probably know that we can express the proportionality relationship between the amount of material we start with, N, and the amount of material that decays, ΔN, by a simple differential relationship of the formwhereλ is the radioactive decay constant that we previously discussedΔt is the amount of elapsed timeThis relationship can also be written as dN = −Nλ dt. All radioactive decay is based on such a relationship. The radioactive decay constant λ for each element (and its individual isotopes) can be determined empirically with great precision. It is this precision that allows us to carbon date materials and thereby determine the age of various extinct animals, plants, and even ancient moon rocks.
Radioactive Materials and Radioactive Decay
Published in Robert E. Masterson, Nuclear Engineering Fundamentals, 2017
The decay fraction is independent of the amount of atoms in a sample. On the other hand, the number of atoms that decay is directly proportional to how many atoms you start with. The more atoms there are in the sample, the more atoms there are that will decay. The constant of proportionality that expresses the relationship between the number of atoms you start with and the number of atoms that decay is called the radioactive decay constant. The radioactive decay constant has the units of inverse seconds (s−1) or inverse time. Each element and its isotopes have a different radioactive decay constant. The radioactive decay constant is usually referred to in scientific literature by the symbol λ (lambda). The radioactive decay constant has the units of inverse seconds or, more generally, inverse time. If you are familiar with college math or calculus, you probably know that we can express the proportionality relationship between the amount of material we start with, N, and the amount of material that decays, ΔN, by a simple differential relationship of the form
Overview of biological mechanisms of human carcinogens
Published in Journal of Toxicology and Environmental Health, Part B, 2019
Nicholas Birkett, Mustafa Al-Zoughool, Michael Bird, Robert A. Baan, Jan Zielinski, Daniel Krewski
Emissions from coal-tar pitch and roofing-tar were mutagenic in S. typhimurium in the presence of an exogenous metabolic activation system, and in two mammalian cell systems in the presence and absence of an exogenous metabolic activation system. These emissions induced sister chromatid exchange in Chinese hamster ovary cells and enhanced viral transformation in Syrian hamster embryo cells both in absence and presence of an exogenous metabolic activation system. Coal tar applied topically to the skin of male mice produced a complex pattern of DNA adducts and markedly elevated the mutation frequency in lambda-lacZ transgenic mice (MutaMouse). DNA strand-breaks were detected in exposed mice. The urine from psoriasis patients undergoing coal-tar treatments was mutagenic in bacteria. Peripheral blood lymphocytes of workers occupationally exposed to coal tars exhibited increased chromosomal damage.
Rapid label-free detection of E. coli using a novel SPR biosensor containing a fragment of tail protein from phage lambda
Published in Preparative Biochemistry and Biotechnology, 2018
Genetic analyses of tail protein J from phage lambda[32] have suggested that the C-terminal portion of the 1132-amino-acid protein might be sufficient for binding to LamB, the surface receptor of its target, E. coli K-12.[33] LamB is a nonspecific channel in the outer membrane, allowing the diffusion of small molecules, such as maltose and maltodextrins. Wang et al. constructed a fusion protein in which the C-terminal portion of the J protein was fused to maltose-binding protein (MBP), and confirmed its ability to bind LamB. However, it was shown that the binding of the fusion protein to LamB only partially reduced the uptake of maltose, and that one-third of LamB molecules did not bind to the fusion protein,[33] suggesting that the presence of the large MPB (∼42 kDa) in the fusion protein might cause steric hindrance.