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Genotoxicity of Functionalized Nanoparticles
Published in Vineet Kumar, Praveen Guleria, Nandita Dasgupta, Shivendu Ranjan, Functionalized Nanomaterials II, 2021
Varsha Dogra, Gurpreet Kaur, Rajeev Kumar, Sandeep Kumar
ROS can be detected by fluorescein-compound based test or by electron paramagnetic resonance (EPR). ROS, when coming into contact with fluorescein-compounds such as 2′,7′- difluorescein-diacetate (Wilson et al. 2002; Lin et al. 2006) and dichlorodihydrofluorescein diacetate (Hussain et al. 2005), it results in oxidization and gives fluorescence (Wilson et al. 2002; Long et al. 2007). EPR is a method of detecting materials with unpaired electrons and it is a helpful technique for the detection of radicals such as reactive oxygen and nitrogen species (Fubini and Hubbard 2003).
Nondestructive Evaluation (NDE) of Materials and Structures from Production to Retirement
Published in Yoseph Bar-Cohen, Advances in Manufacturing and Processing of Materials and Structures, 2018
EPR and NMR techniques are very similar; the main difference is that EPR is microwave induced and NMR is radiofrequency-induced transitions of magnetic energy levels of atomic nuclei. NMR has become a major tool for the investigation of the microscopic structure and properties of matter since it was developed in 1945 (Sasaki, 2016). This technique is useful for determining molecular structure and for monitoring chemical reaction mechanisms and rates without affecting the structure, mechanism, or rates of the material or reaction being investigated. EPR is particularly useful for determining molecular structures and monitoring chemical reactions without affecting the samples being examined (Bardet et al., 2009). Out of these two techniques, so far, only NMR has been used as an imaging tool. However, imaging uses no ionizing radiation, and thus, it is nonhazardous. Outside the medical field, NMR has been used for detecting explosives in packages and for determining the moisture content of composite materials (Bouznik et al., 2016).
Methods for Characterizing (Phosphorus) Dendrimers
Published in Anne-Marie Caminade, Cédric-Olivier Turrin, Jean-Pierre Majoral, Phosphorus Dendrimers in Biology and Nanomedicine, 2018
Anne-Marie Caminade, Régis Laurent
EPR is used for studying compounds having one (or more) unpaired electron. Besides metallic radicals, which are mainly characterized by electrochemistry (see Section 2.2.10), the most widely used radicals are various nitroxides. The generation zero of PPH dendrimer functionalized by 6 TEMPO radicals as terminal groups was characterized by X-ray crystallography, which displayed the organization of three branches up and three branches down, relative to the cyclotriphosphazene core in the solid state. Characterization of the same compound by EPR in solution displayed the same geometry, as shown by seven lines centered at g = 2.0066 and separated by ca. 5.0 G in the EPR spectrum. This corresponds to a spectrum generated by the interaction of three TEMPO radicals [48].
Theoretical studies of the Spin Hamiltonian parameters and local structures for Cu2+ centers in MNB ternary glasses
Published in Radiation Effects and Defects in Solids, 2018
Ternary glasses doped with transition-metal (TM) ions exhibit novel properties of optical absorption (1), dielectric (2), photoluminescence (3, 4), ionic conduction (5) and can act as glass-ceramics (6, 7) and laser hosts (8). The TM dopants usually play a crucial role in the above properties because of the unique and abundant electronic energy levels closely related to their immediate environments in the hosts. As is known, electron paramagnetic resonance (EPR) is a powerful technique to study defect structures and electronic properties of paramagnetic TM ions in crystals. The EPR spectra provides a detailed information of the ground state of the doped TM ions and enables one to understand the nature of the crystal field symmetry produced by the ligands around the TM ions. Copper (Cu2+) is a model system with a single 3d hole, corresponding to only one ground state and one excited state under ideal octahedral crystal-fields. Thus, Cu2+ as a topical doping ion was usually applied as probes to provide useful information of the local structures for the studied systems by means of EPR technique over recent years (9–12). For example, the EPR experiments were carried out on the ternary glasses xMgO·(30-x)Na2O·69B2O3 (with MgO concentration 5 ≤ x ≤ 17 mol%) (MNB, hereafter) doped with Cu2+ (in the form of CuO), and the spin Hamiltonian parameters (SHPs) for these Cu2+ centers (the anisotropic g factors g|| and g⊥ and the hyperfine structure constants A|| and A⊥) were measured for various concentration x (13).
Asphaltenes of crude oils and bitumens: The similarities and differences
Published in Petroleum Science and Technology, 2022
Yulia Ganeeva, Ekaterina Barskaya, Ekaterina Okhotnikova, Tatiana Yusupova, Vladimir Morozov, Gennady Romanov
Electronic paramagnetic resonance (EPR) is a useful method for the investigation of paramagnetic species. In most cases, EPR spectra of asphaltenes show an intense central signal with g value close to that of the free electron (g = 2.0023), which is assigned to stable free radical (FR), and hyperfine structure characteristic to vanadyl ions, VO+2, due to coupling of the electron spin (S = 1/2) with the nuclear spin of vanadium (I = 7/2) (Figure 4).
Electron paramagnetic resonance of globin proteins – a successful match between spectroscopic development and protein research
Published in Molecular Physics, 2018
Sabine Van Doorslaer, Bert Cuypers
Parallel to the developments of pulsed EPR, high-field/high-frequency EPR has been introduced [31]. The use of higher magnetic fields, and thus higher mw frequencies, in (CW) EPR or hyperfine spectroscopy allows for a better resolution of features that are overlapping at the standard mw frequencies. However, as we will see later for the ferric globin case, this may come at a cost in signal intensity for very anisotropic g tensors.