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Basic Atomic and Nuclear Physics
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Gudrun Alm Carlsson, Michael Ljungberg
An electron from the surrounding electron shell is captured by the nucleus, and it interacts with a proton, which results in the formation of a neutron and a neutrino. The process is called electron-capture (EC), and when capturing an electron from the K-shell, one defines this as a K-capture. The likelihood is the largest for electrons captured in the shells closest to the nucleus, especially those with the quantum number l=0. The nucleus reduces Z (number of protons) by one, while A remains unchanged. Electron capture is drawn as a decay diagram in Figure 2.14.
Nuclear Structure and Decay
Published in Eric Ford, Primer on Radiation Oncology Physics, 2020
Other possible nuclear decay modes are shown in Figure 2.2.5. In electron capture (EC) an inner-shell electron interacts with the nucleus and the result is that a proton is lost. An example of such a decay is 125I (iodine) decaying into 125mTe (tellurium) in a metastable state, i.e. a high energy state of the nucleus that lasts for a long time but eventually decays into a ground state. After EC there is a vacancy in an inner shell electron and an outer shell electron can transition into this state, producing a characteristic photon. Auger electrons can also be emitted. For more on characteristic photons and Auger electrons see Section 5.1.2.
Biomedical Imaging Molecular Imaging
Published in Lawrence S. Chan, William C. Tang, Engineering-Medicine, 2019
Christian J. Konopka, Emily L. Konopka, Lawrence W. Dobrucki
EC is the second method by which unstable neutron deficient nuclides decay. In general, neutron deficient isotopes which are of high atomic number decay more predominantly by electron capture, whereas those with lower atomic numbers will decay primarily by β+ decay. During EC the positive charge in the nucleus is decreased when a K-shell electron is captured by the parent nucleus. This capture results in the conversion of a proton to a neutron and the ejection of a neutrino and can be represented by the equation:
9th international symposium on physical, molecular, cellular, and medical aspects of Auger processes: preface
Published in International Journal of Radiation Biology, 2023
Katherine A Vallis, Roger F. Martin, Nadia Falzone
Removal of an inner orbital electron through the photoelectric effect, electron capture, or internal conversion leads to a vacancy which is then filled by a cascade of electron transitions from the outer shells. These transitions are accompanied by the emission of low energy ‘Auger’ electrons or characteristic X-rays. Auger electrons have low energy (<25 keV), have a short track length and are densely ionizing. As a result, the absorbed radiation dose they deposit in biological material is extremely high but restricted to a nanoscale volume (a few nm3) around the decay site. These qualities mean that Auger electron emitting radionuclides are suited to the ultra-precise delivery of radiation to individual cells, organelles or even to specific molecular targets, and so hold promise as oncologic therapeutic agents.
A perspective toward mass spectrometry-based de novo sequencing of endogenous antibodies
Published in mAbs, 2022
Sebastiaan C. de Graaf, Max Hoek, Sem Tamara, Albert J. R. Heck
In electron-based techniques, such as electron capture-induced dissociation (ECD), positively-charged peptide ions capture electrons, leading to the generation of odd-electron species that dissociate promptly without significant vibrational redistribution.56–58 In contrast to collisional dissociation, this process is not directed toward the most labile bonds, and produces distinctively c and z fragment ions through the dissociation of N-Cα bond (Figure 4c). Similarly, high-energy ultra-violet photon-based activation and dissociation techniques (UVPD) also cause bond dissociation without substantial energy redistribution. This is enabled by a number of chromophores along the peptide backbone and results in a wide array of co-occurring fragment ion types (a/x, b/y, c/z), depending on the wavelength used.51,52 Highly energetic fragmentation methods can also lead to w-type ions, which involve an amino acid side-chain dissociation.59,60 In de novo sequencing, this may be advantageous since it allows leucine and isoleucine to be distinguished, although they have identical masses.
Quercetin Antagonizes Esophagus Cancer by Modulating miR-1-3p/TAGLN2 Pathway-Dependent Growth and Metastasis
Published in Nutrition and Cancer, 2022
Yuyin Wang, Xia Chen, Jun Li, Chenmei Xia
Currently, the most effective treatment strategy against EC is chemotherapies, which can induce cytotoxicity on EC cells by increasing apoptosis and suppressing distance metastasis of cancer. However, chemotherapies are still rendered less satisfactory considering the general side effects. As a natural compound abundant in fruits and vegetables, Que is characterized by low cell toxicity. In our study, we assessed the effects of the compound on the proliferation and metastasis of EC cells. The data showed that the administration of Que suppressed the viability and invasion of EC cells, confirming the anti-EC effects of Que. To further explain the mechanism driving the function of Que, we also detected the changes in miR-1-3p/TAGLN2 axis. It was found that with the treatment of Que, the expression of miR-1-3p was induced, while the expression of TAGLN2 was inhibited. Moreover, the inhibition of miR-1-3p in Que-treated ECs restoredcell viability and invasion ability, which implied that the induction of miR-1-3p was indispensable for anti-EC function of Que.