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New Trends
Published in Vlado Valković, Low Energy Particle Accelerator-Based Technologies and Their Applications, 2022
Single ions can be used to deliver precisely controlled ionization energy to selected regions of living cells, enabling radiation effects to be followed with precision, overcoming many of the limitations of statistical studies. These single-ion applications offer major advances on previous work with collimated beams. Here we presented some of the centers active in this field.
Chemistry and Isotopes of Iodine
Published in Erwin Regoeczi, Iodine-Labeled Plasma Proteins, 2019
The energy required to break an electron away from an atom is termed ionization energy. The level of this energy depends on the electron configuration of the atom and is highest for the elements having completed (full) quantum shells, i.e., the noble gases (formerly known as inert gases) in group VIII. The stability of these gases is said to be conferred on them by their stable electron configuration. In addition to the occupancy of the outermost quantum shell present, the distance of this shell from the nucleus is also a determinant of the ionization energy: both helium (small atom) and radon (large atom) are noble gases, and yet the ionization energy for the former is 566.7 kcal/mol as contrasted by 247.8 kcal/mol for the latter. For more details regarding the relationship between atomic number and ionization energy the interested reader is referred to the literature.1
Fundamental Concepts and Quantities
Published in Shaheen A. Dewji, Nolan E. Hertel, Advanced Radiation Protection Dosimetry, 2019
The energy associated with an electron in the ground state in a hydrogen atom is −13.6 eV. As discussed earlier, if sufficient energy is imparted to this electron, it can move to excited orbital states. If energy greater than the ground state (e.g., 13.6 eV for hydrogen) is imparted to the electron, it is removed completely from the bound state (). This process is termed ionization and results in a free electron and a positively charged nucleus. It is important to note that the amount of energy that can be absorbed is essentially limitless and excess energy greater than the ionization energy is manifested in the form of kinetic energy of the electron. For electromagnetic radiation , and this corresponds to a minimum frequency (or conversely, maximum wavelength, since ) required to produce ionization.
Risk assessment of heterogeneous TiO2-based engineered nanoparticles (NPs): a QSTR approach using simple periodic table based descriptors
Published in Nanotoxicology, 2019
Joyita Roy, Probir Kumar Ojha, Kunal Roy
Ionization potential is the difference of energy between the ground state and state of ionization, and this amount of energy is required to completely remove the loosely attached electrons. The 2nd ionization potential is greater than 1st ionization potential and depends upon the size, charge and the type of electrons removed from outer shell of the atom. Ionization potential also determines the electronegativity and electron affinity of an atom. The low ionization energy of an atom (the energy required to remove the outer shell electron) indicates that the atom can easily lose its outer shell electron and has fewer tendencies to gain electrons. Thus, it clearly indicates that the atoms with high ionization potential will have high electronegativity. The electronegativity is responsible for the catalytic property of the cationic form of the metal and therefore increases the cytotoxicity. The positive regression coefficient of this descriptor indicated that an atom with higher 2nd ionization potential increases the cytotoxicity of the hamster ovary cell and vice versa. As for example, the nanoparticles 6.5Ag_0.5Pt and 6.5Ag are highly toxic (toxicity values are 5.8 and 5.88 respectively) towards the cytotoxicity to hamster ovary cell due to their higher range of 2nd ionization potential (14350.5 and 13455 respectively), whereas in case of nanoparticles 0.25Pt and 0.1Au, the cytotoxicity (4.56 and 4.67 respectively) decreases with its 2nd ionization potential (447.75 and 198 kJ/mol respectively).
Determination of polycyclic aromatic hydrocarbons (PAHs) in carbon black-containing plastic consumer products from the Jordanian market
Published in Toxin Reviews, 2018
Mahmoud A. Alawi, Rana A. Abdullah, Ibrahim Tarawneh
A Gas chromatograph type Agilent 6890 series II with Auto sampler injector series 7683 was used under the following conditions:Injection volume: 2 μL/splitless.Column: BBX-5 (30 cm ×0.25 mm I.D. × 0.25 μm film thickness).Carrier gas: Helium (99.999%), (8 psi)Temperature program 100 °C (10 min), 100–160 °C (25 °C/min), 160–270 °C (5 °C/min), 270 °C isotherm (27 min)Detector: mass selective quadruple – detector, Agilent 5973 N (MSD)Auxiliary (transfer line): 280 °C, Electron Impact Ionization.Ionization Energy: 70 eV.Calibration substance: Perflourotributylamine (PFTBA)Tuning masses: 69/219/502Acquisition mode: Selective ion monitoring (SIM) – mode.Data analysis: HP MSD productivity Chemstation SW.
Synthesis, X-ray structure, in silico calculation, and carbonic anhydrase inhibitory properties of benzylimidazole metal complexes
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Mehdi Bouchouit, Sofiane Bouacida, Bachir Zouchoune, Hocine Merazig, Silvia Bua, Zouhair Bouaziz, Marc Le Borgne, Claudiu T. Supuran, Abdelmalek Bouraiou
The ionisation energy and electron affinity (EA) are important parameters for the understanding the stability towards the removing of one electron from HOMO and the attachment of one electron to LUMO, respectively. Furthermore, the HOMO-LUMO gap has served as a simple measure of kinetic stability, where a molecule with a small or no HOMO-LUMO gap is chemically reactive36, thus, the HOMO-LUMO energy separation can be used as a simple indicator for kinetic stability, where a large gap implies high kinetic stability and low chemical reactivity, because it is energetically unfavourable to extract electrons from a low-lying HOMO and to add electrons to a high-lying LUMO. Generally in simple molecular orbital theory approaches, the HOMO energy (EHOMO) is related to the IP by Koopmanns’ theorem. The adiabatic ionisation potential is obtained by using Equation (1) in which M and M+ were the neutral and oxidised form for the optimised structures37. The adiabatic electron affinities are calculated by taking the difference between the total energy of the neutral ground state (M) and that of the negatively charged complexes (M–) for the optimised structures as given by Equation (2).