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Structure of Matter
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
To characterise a given nuclide, the following symbolism is used: , in which X is the element nuclide symbol, Z the atomic number and A the mass number. Isotones are atoms that have the same number of neutrons (i.e. A–Z), such as .Isotopes are atoms that have the same number of protons (Z) with a different number of neutrons. They are therefore different versions of the same element. Many elements are made of a mixture of several isotopes, with a fairly stable composition. An effective mass number A for such elements may then be calculated and is not necessarily an integer.Isobars are atoms that have the same number of nucleons (value of A) but belong to different elements because they have different values of Z (e.g. ).
Physics for medical imaging
Published in Ken Holmes, Marcus Elkington, Phil Harris, Clark's Essential Physics in Imaging for Radiographers, 2021
All atoms have a specific atomic number and this is based on the number of protons in the nucleus. For example, naturally occurring carbon has 6 protons forming part of its nucleus and therefore has an atomic number of 6.
Physics of Radiation Biology
Published in Kedar N. Prasad, 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).
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.
Calculation of the initial DNA damage induced by alpha particles in comparison with protons and electrons using Geant4-DNA
Published in International Journal of Radiation Biology, 2020
Hossein Moeini, Mojtaba Mokari, Mohammad Hassan Alamatsaz, Reza Taleei
We used Geant4-DNA (Geant4 v10.4) for particle transportation and simulation of the interaction of the primary alphas and secondary particles with a body of water. The toolkit works out both physical and chemical interactions and renders information such as energy depositions and corresponding interaction positions in a step-wise manner along the propagation of particles. The important processes for DNA damage calculations that are dealt with in Geant4-DNA include elastic, ionization, excitation, and Auger cascades. The tracking cutoff for electrons was set to 7.4 eV, below which the tracking stops and the particle energy is locally deposited. A physical interaction in Geant4-DNA was described by a physics process which can be associated with complementary or alternative cross-section models (Incerti et al. 2010). The employed electron, proton, and hydrogen atom models in this work and their corresponding energy ranges are explained in previous publications (Mokari, Alamatsaz, Moeini, Taleei 2018; Mokari, Alamatsaz, Moeini, Babaei-Brojeny, et al. 2018). The alpha models used for nuclear scattering (100–1 MeV), electronic excitation (1–400 MeV), ionization (0–400 MeV), and charge decrease (1–400MeV) were G4DNAIonElasticModel, G4DNAMillerGreenExcitationModel, G4DNARuddIonisationModel and G4DNARuddIonisationExtendedModel, and G4DNADingfelderChargeDecreaseModel, respectively (De la Fuente Rosales et al. 2018).
Comprehensive characterisation of the heterogeneity of adalimumab via charge variant analysis hyphenated on-line to native high resolution Orbitrap mass spectrometry
Published in mAbs, 2019
Florian Füssl, Anne Trappe, Ken Cook, Kai Scheffler, Oliver Fitzgerald, Jonathan Bones
Data analysis was performed in Thermo Scientific BioPharma Finder™ 2.0 software using the ReSpect™ algorithm for deconvolution. Deconvolution of spectra of main lysine variants was performed using the Sliding Window deconvolution feature. All other analyses were based on deconvolution after manual peak integration. The average molecular masses obtained after deconvolution were compared to the theoretical mass of intact adalimumab considering G0F/G0F, G0F/G1F and G1F/G1F or G0F/G2F glycoforms as well as theoretical masses of modifications such as: single and double lysine loss, glycation, single and double deamidation, succinimide formation, Asp loss or double C-terminal proline amidation and fragmentation. Exact masses used for comparison and annotation were obtained by using the atomic weights and isotopic compositions provided by the Commission on Isotopic Abundances and Atomic Weights. Details on the BioPharma Finder™ 2.0 parameter settings used can be found in Table S3 in the Supporting Information.