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Land Contamination
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
Radioactive decay occurs when an unstable atomic nucleus spontaneously loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type (parent nuclide) transforming into an atom of a different type (daughter nuclide). All elements with an atomic number greater than 80 possess radioactive isotopes, and all isotopes of elements with an atomic number greater than 83 are radioactive (Kathren 1991).
Chemistry of Contaminants
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
Radioactive decay occurs when an unstable atomic nucleus spontaneously loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type (parent nuclide) transforming into an atom of a different type (daughter nuclide). All elements with an atomic number greater than 80 possess radioactive isotopes, and all isotopes of elements with an atomic number greater than 83 are radioactive (Kathren 1991).
Perspectives
Published in Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff, Radiation and Radioactivity on Earth and Beyond, 2020
Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff
Nuclear fusion is a reaction between light atomic nuclei which lead to formation of a heavier nucleus and the release of an important amount of energy. One way to fusion is penetrating the Coulomb barrier by force, by giving the nuclei a huge amount of kinetic energy. This usually requires heating the particles to tens of millions degrees. The process operates in the stars (Chapter 5) and was demonstrated on Earth with the explosion of the first thermonuclear device. The other way is to try to screen one nucleus from the repulsive effects of the other by binding the nuclei with a particle of opposite charge. The muonic hydrogen atom may be the right tool.
Modeling and optimization for adsorption of thorium (IV) ions using nano Gd:ZnO: application of response surface methodology (RSM) and artificial neural network (ANN)
Published in Inorganic and Nano-Metal Chemistry, 2022
Thorium is the second member of the actinides section of the periodic table and was discovered by Jöns Jacob Berzelius in 1828. It constitutes approximately 0.0007% of the earth's crust. This element is included in the structure of approximately 60 minerals and is not found in free form in nature like uranium. Structurally, it is mostly used by being produced in Taurite Monazite mineral. There are twenty-seven unstable isotopes of thorium (212-237Th) in nature, and there are only 232Th in nature.[28] It has the longest half-life of any natural isotope that begins with the emission of radioactive 232Th alpha particles and stabilizes at 208Pb by emitting beta and gamma rays. This element is three or four times more abundant than uranium in the earth's crust. It is used in increasing the resistance of magnesium in alloys at high temperatures, coating tungsten filaments in lighting, electronic devices, high-quality camera lenses, making high-temperature resistant crucibles, and in nuclear technology and laboratories. As an element with a low toxic effect, radioactive minerals such as uranium and thorium pose a radioactive risk with rays such as alpha, beta, and gamma as a product of the fragmentation of the atomic nucleus.[29]
Synthesis, theoretical DFT analysis, photophysical and photochemical properties of a new zinc phthalocyanine compound
Published in Inorganic and Nano-Metal Chemistry, 2022
Mehmet Salih Ağırtaş, Derya Güngördü Solğun, Umit Yıldıko
Molecular electrostatic potential (MEP) electron density is a very useful descriptor in identifying electrophilic and nucleophilic reactions in the compound and understanding hydrogen bonding interactions.[34,41–43] In order to estimate the reactive regions of electrophilic or nucleophilic attacks for the phthalocyanine molecule examined in study, MEP was calculated with optimized geometry at B3LYP and CAMB3LYP/6-311G levels. For different electrostatic potential values on the MEP surface, red represents the most negative, blue represents the most positive and green represents the neutral electrostatic potential regions. Negative electrostatic potential corresponds to proton withdrawal, while positive electrostatic potential corresponds to proton propulsion by the atomic nucleus. Figure 9 shows the MEP graph for zinc phthalocyanine compound calculated by B3LYP-CAMB3LYP methods. It is clear from the MEP that the negative charge includes substituent groups and that the positive region is predominantly on the metal atom (Zn41), the hydrogen of the aromatic ring, and the hydrogen corresponding to the methyl groups (Figures 10 and 11).
Determination of acid dissociation constants and reaction kinetics of dimethylamine-based PPCPs with O3, NaClO, ClO2 and KMnO4
Published in Journal of Environmental Science and Health, Part A, 2019
Xiaofeng Wang, Beihai Zhou, Xia Shao
Doxylamine and carbinoxamine contain a pyridine group that can obtain a proton. The pKa values of doxylamine and carbinoxamine believed to correspond to the pyridine group were 5.5 and 6.2, respectively. The pKa value of the pyridine molecule was 5.25. The lone pair electrons on nitrogen in pyridine are in the sp2 hybrid orbitals where the s orbital part is greater than that in the sp3 hybrid orbitals. The strong attraction of the atomic nucleus leads to a weak proton binding capacity. The pyridine group has a weaker alkalinity than the DMA group.