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Elements of Nuclear Energy
Published in C. K. Gupta, Materials in Nuclear Energy Applications, 1989
The atom, the basic unit of matter, as first modeled by Neils Bohr in 1913, consists of a heavy central nucleus surrounded by orbital electrons. The nucleus, in turn, consists of two types of particles, namely, protons and neutrons. Particles inside a nucleus are also collectively referred to as nucleons. The positive charge of the nucleus results from the presence of protons in it. Negatively charged particles called electrons whirl around the nucleus in well-defined orbits/shells at different radial distances from the nucleus. The chemical designation of a given atom is determined by the number of protons in the nucleus. The number of protons denotes the electrical charge of the nucleus and is designated by the letter Z, called the atomic number. A complete atom has the same number of protons and electrons. This accounts for its electrical neutrality. The charge (number of electrons or number of protons) uniquely determines the chemical properties of an atom. The number of neutrons in the nucleus has no effect upon the chemical characteristics of the atom, but does affect the mass. The position of elements in the periodic table is based on their atomic numbers. The sum of the numbers of protons and neutrons in the nucleus is known as the mass number — denoted by the symbol A — and is an index of the mass of the atom. The number of neutrons in the nucleus is thus given by A to Z. A useful shorthand notation for nuclear species or nuclides is ZXA, where X is the chemical symbol, Z is the atomic number, and A is the mass number. Actually, the subscript Z is superfluous because the chemical symbol identifies the number of protons in the nucleus. The use is, therefore, somewhat discretionary. However, the inclusion of the subscript is regarded as a convenient aid in nuclear reaction equation balancing. The characteristics of atomic and nuclear constituents are shown in Table 1. The mass of the atom with a diameter of approximately 10−8 cm is mostly concentrated in the central nucleus with a diameter of approximately 10−12 cm. The proton is 1837 times heavier than the electron, while the mass of the neutron is slightly greater than that of a proton. The charge of an electron is 4.8 × 10−10 electrostatic units (esu) and is the smallest charge known to exist. The number of neutrons in the nucleus of an atom of a given chemical element is not fixed, although the number of protons is fixed. Atoms of an element differing from each other only in the number of neutrons are called isotopes. Isotopes of a given element are indistinguishable chemically, but may be identified by their differences in mass. In nature, there are more than 20 elements which have no isotopes. They are refereed to as anisotopic.
Characterization of soluble and insoluble fractions obtained from a commercial pea protein isolate
Published in Journal of Dispersion Science and Technology, 2022
Pascal Moll, Hanna Salminen, Oskar Seitz, Christophe Schmitt, Jochen Weiss
To determine mineral composition, a microwave heated (ultraCLAVE, MLS GmbH, Leutkirch, Germany) pressure digestion with nitric acid and hydrogen peroxide was performed according to method 2.1.3.[24] A mineral analysis was subsequently carried out by inductively coupled plasma atomic emission spectroscopy (5110, Agilent, Santa Clara, CA, USA) as stated in method 8.10.[24] Total sulfur was determined by dry combustion (Vario EL, Elementar, Langenselbold, Germany) according to ISO 15178:2000.[25] Based on the mineral composition, the molar ionic strength I (mol L−1) was calculated according to Eq. 2: where ci is the molar concentration of ion i (mol L−1) and zi is the charge number of ion i. Sulfur was not considered for this calculation as it was expected to be bound to amino acids, thereby not contributing to ionic strength.
Radiation effects of hydrogen beam injection into a boron-11 tokamak plasma
Published in Radiation Effects and Defects in Solids, 2023
For simplicity, the collision process is assumed to be classical. In this state, the parameter can be determined with the assistance of the slowing-down relation as (19) where is the charge number of energetic hydrogen ions, m is the mass of electrons, is the Coulomb logarithm and is selected as 20, and the function is defined as
Computational Fluid Dynamics Simulation of Fouling of Plate Heat Exchanger by Phosphate Calcium
Published in Heat Transfer Engineering, 2022
Ulla Ojaniemi, Timo Pättikangas, Ari Jäsberg, Eini Puhakka, Antti Koponen
Ion strength I for the solution iswhere ci is the molar concentration of species i, and zi is the charge number of ion i. The total ion strength of the SMUF is of the order of 0.1 M. Therefore, the activity of the ion is derived from the Davies equationwhere is determined with temperature in Celsius [9].