Basic Radiological Science
Thomas A. Carder in Handling of Radiation Accident Patients, 1993
As explained in Sections 2 and 3, electrons and their configuration around the nucleus of the parent atom are responsible for the chemical properties of elements. The configuration of electrons also determines the chemistry of a compound or of compounds. The living cells within the human body depend on specific and exact chemical relationships between elements and compounds. Compound molecules depend on chemical bonding between element atoms to form molecular units. The bonding between the atoms of a molecule is provided by atoms sharing electrons in the outermost shells. The electrons shared by atoms to form a molecule are called valence electrons. Loss of one or more of the valence electrons can alter the chemistry of the molecule.
Physics of Radiation Biology
Kedar N. Prasad in Handbook of RADIOBIOLOGY, 2020
Electrons are negatively charged particles and orbit the atomic nucleus in a precisely defined path, each path being characterized by its own unique energy level. Electrons are positioned in shells or energy levels that surround the nucleus. The first or K shell contains no more than 2 electrons, the second or L shell no more than 8 electrons, and the third or M shell no more than 18 electrons (Figure 3.2). The outermost electron shell of an atom, no matter which shell it is, never contains more than 8 electrons. Electrons in the outermost shell are termed valence electrons and determine to a large degree the chemical properties of an atom. An atom with an outer shell filled with electrons seldom reacts chemically. These atoms constitute elements known as the inert gases (helium, neon, argon, krypton, xenon, and radon).
Radiation detection and measurement
Alan Martin, Sam Harbison, Karen Beach, Peter Cole in An Introduction to Radiation Protection, 2018
The term solid-state detectors refers to certain classes of crystalline substances that exhibit measurable effects when exposed to ionizing radiation. In such substances, electrons exist in definite energy bands separated by forbidden bands. The highest energy band in which electrons normally exist is the valence band. The transfer of energy from a photon or charged particle to a valence electron may raise it from the valence band through the forbidden band into either the exciton band or the conduction band. The vacancy left by the electron is known as a ‘hole’ and it is analogous to a positive ion in a gas system.
Drinking motives, cultural orientations, and alcohol use among Hispanic college students at the U.S.–Mexico border
Published in Journal of Ethnicity in Substance Abuse, 2022
P. Priscilla Lui, Byron L. Zamboanga, Melissa M. Ertl, Lindsey M. Rodriguez, Jessica L. Martin, Rubi Gonzales
According to the motivational model of alcohol use and supported by empirical data, drinking motives are the most robust and proximal determinants of alcohol use (Cooper, 1994; Cooper et al., 2016; Cox & Klinger, 1988; Kuntsche et al., 2010). Drinking motives often are learned through observations and social interactions with family and friends (LaBrie et al., 2007). Current conceptualizations of drinking motives include dimensions of valence and source (Cooper, 1994). Valence describes positive outcomes (e.g., to improve parties and celebrations) or negative outcomes (e.g., to forget one’s problems) that individuals expect to receive from alcohol use. Motivations to drink can come from internal sources such as forgetting personal problems or external sources such as wanting to be liked by others. Crossing valence and source dimensions results in four distinctive drinking motives: social (positive valence and external source), enhancement (positive valence and internal source), coping (negative valence and internal source), and conformity motives (negative valence and external source; Cooper, 1994).
Quantitative structure–toxicity relationship models for predication of toxicity of ionic liquids toward leukemia rat cell line IPC-81 based on index of ideality of correlation
Published in Toxicology Mechanisms and Methods, 2022
Shahin Ahmadi, Shahram Lotfi, Parvin Kumar
Hybrid descriptors are calculated by the addition of descriptors of correlation weights (CWs) of the SMILES and descriptors of CWs of the molecular graph (Equation (1)) (Toropova and Toropov 2014; Ahmadi and Akbari 2018; Bagri et al. 2020; Lotfi et al. 2020). SMILES based descriptor is obtained by the summation of the CWs of various SMILES attributes of a given molecule (Equation (2)). Similarly, the graph-based descriptor can be obtained using (a) the numbers of paths of length (pk), (b) Valence shells (sk), and (c) the nearest neighbors (nnk) (Equation (3)). T* is the optimal number of thresholds (T) and N* is the number of epochs (N).
Electronic properties of DNA-related molecules containing a bromine atom
Published in International Journal of Radiation Biology, 2023
Misaki Hirato, Misato Onizawa, Yuji Baba, Yoshinori Haga, Kentaro Fujii, Shin-ichi Wada, Akinari Yokoya
The XANES and XPS results showed that the photoelectron binding energies and the K-shell absorption energies of C, N, O, and P were similar, regardless of the presence of a Br atom. Because XANES spectra arise from the transition of the core electrons to the unoccupied level, information about the electronic state of the unoccupied level can be obtained. XPS measurements provide information about the electronic state of the core level by comparing the binding energies of photoelectrons. These results suggest that the Br atom does not contribute substantially to the electronic states of the molecules, particularly for the core level and LUMO, but does contribute to the state related to the excitation of the lattice vibration (oscillation and rotation in the molecule). In addition, we are currently investigating the effect of a Br atom on the valence electronic states involved in the chemical bond.
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