Search results for "spin resonance"
showing 10 items of 156 documents
Electron Spin Resonance study of charge trapping in α-ZnMoO4 single crystal scintillator
2015
The origin and properties of electron and hole traps simultaneously appearing in a-ZnMoO4 scintillator after X-ray irradiation at low temperatures (T < 35 K) were studied by Electron Spin Resonance (ESR). ESR spectrum of the electron type trap shows pronounced superhyperfine structure due to the interaction of electron spin with nuclear magnetic moments of 95,97Mo and 67Zn lattice nuclei. Considering the nearly tetragonal symmetry of the center this allows us to identify the electron trap as an electron self-trapped at the (Mo(1)O4) 2 complex. Nearly 60% reduction of the spin–orbit coupling at the Mo(1) ion is caused by the overlap of the Mo and ligand oxygen orbitals indicating an essentia…
Physiological Levels of Nitric Oxide Diminish Mitochondrial Superoxide. Potential Role of Mitochondrial Dinitrosyl Iron Complexes and Nitrosothiols.
2017
Mitochondria are the major source of superoxide radicals and superoxide overproduction contributes to cardiovascular diseases and metabolic disorders. Endothelial dysfunction and diminished nitric oxide levels are early steps in the development of these pathological conditions. It is known that physiological production of nitric oxide reduces oxidative stress and inflammation, however, the precise mechanism of “antioxidant” effect of nitric oxide is not clear. In this work we tested the hypothesis that physiological levels of nitric oxide diminish mitochondrial superoxide production without inhibition of mitochondrial respiration. In order to test this hypothesis we analyzed effect of low p…
The effect of organic solvents on selected microorganisms and model liposome membrane
2019
The effect of methanol, ethanol, acetone, N,N-dimethylformamide (DMF), dimethyl sulfoxide and Nujol on the growth of Escherichia coli DH5α, Bacillus subtilis and Saccharomyces cerevisiae D273 was investigated. All of the tested cultures appeared susceptible to the organic media they were treated with, which evinced in apparent hindering of cell development. The observed diverse solvent tolerance, except from their different biochemical activity, may also be related to the changes in cell membrane fluidity induced by the solvent species. Parallel electron paramagnetic resonance investigations using egg yolk lecithin model liposomes revealed that the fluidity of the phospholipid system in cel…
Oxidation-Induced Increase In Photoreactivity of Bovine Retinal Lipid Extract
2017
Open access original paper Source : 10th EPR Workshop on Applications of EPR in Biology and Medicine, 2016 in Krakow, POLAND.; International audience; The mammalian retina contains a high level of polyunsaturated fatty acids, including docosahexaenoic acid (22:6) (DHA), which are highly susceptible to oxidation. It has been shown that one of the products of DHA oxidation-carboxyethylpyrrole (CEP), generated in situ, causes modifications of retinal proteins and induces inflammation response in the outer retina. These contributing factors may play a role in the development of age-related macular degeneration (AMD). It is also possible that some of the lipid oxidation products are photoreactiv…
The influence of tin compounds on the dynamic properties of liposome membranes: A study using the ESR method
2005
AbstractThe influence of organic and inorganic compounds of tin on the dynamic properties of liposome membranes obtained in the process of dipalmitoylphosphatidylcholine (DPPC) sonication in distilled water was investigated. This was carried out by means of the spin ESR probe method. The probes were selected in such a way as to penetrate different areas of the membrane (a TEMPO probe, 5-DOXYL stearic acid, 16-DOXYL stearic acid). Four compounds of tin were chosen: three organic ones, (CH3)4Sn, (C2H5)4Sn and (C3H7)3SnCl, and one inorganic one, SnCl2. The investigated compounds were added to a liposome dispersion, which was prepared prior to that. The concentration of the admixture was change…
Can copper(II) mediate Hoogsteen base-pairing in a left-handed DNA duplex? A pulse EPR study
2010
Pulse EPR spectroscopy is sued to investigate possible structural features of the copper(II) ion coordinated to poly(dG-dC) poly(dG-dC) in a frozen aqueous solution, and the structural change of the polynucleotide induced by the presence of the metal ion. Two different copper species were identified and their geometry explained by a molecular model. According to this model, one species is exclusively coordinated to a single guanine with the N7 nitrogen atom forming a coordinative bond with the copper. In the other species, a guanine and a cytosine form a ternary complex together with the copper ion. A copper crosslink between the N7 of guanine and N3 of cytosine is proposed as the most prob…
Structural analysis of Cu(II) ligation to the 5'-GMP nucleotide by pulse EPR spectroscopy.
2007
JBIC Journal of Biological Inorganic Chemistry, 12 (6)
Synthesis, Stability and Relaxivity of TEEPO-Met: An Organic Radical as a Potential Tumour Targeting Contrast Agent for Magnetic Resonance Imaging
2018
Cancer is a widespread and life-threatening disease and its early-stage diagnosis is vital. One of the most effective, non-invasive tools in medical diagnostics is magnetic resonance imaging (MRI) with the aid of contrast agents. Contrast agents that are currently in clinical use contain metals, causing some restrictions in their use. Also, these contrast agents are mainly non-specific without any tissue targeting capabilities. Subsequently, the interest has notably increased in the research of organic, metal-free contrast agents. This study presents a new, stable organic radical, TEEPO-Met, where a radical moiety 2,2,6,6-tetraethylpiperidinoxide (TEEPO) is attached to an amino acid, methio…
Lanthanide–saccharide chemistry: synthesis and characterisation of Ce(III)–saccharide complexes
2000
A series of nine Ce(III) complexes has been synthesised with seven different monosaccharides (D-glucose, D-fructose, D-galactose, D-mannose, L-sorbose, D-ribose and D-xylose) and two different disaccharides (D-maltose and L-lactose), and these have been characterised with various analytical, spectral, magnetic and electrochemical techniques. The NMR studies have highlighted some interesting features about the metal-ion-binding pattern of the saccharides. Some additional coordination has been proposed along with the chelating groups in the saccharide molecules, based on the shifts in 13C NMR spectra. On the other hand, solution absorption studies and solid-state magnetic susceptibilities hav…
In-situ observation of beta-ray induced UV optical absorption in a-SiO2: radiation darkening and room temperature recovery
2006
International audience; We studied the optical absorption in the 3.0-6.2 eV range induced in bulk amorphous SiO2 by beta-ray irradiation up to similar to 1 MGy at room temperature. The induced absorption was measured in situ both during irradiation and in the post irradiation time. Our data evidence E', center as the main defect induced by irradiation and the partial decay of their absorption band at about 5.8 eV after irradiation. A quantitative analysis of the time evolution of the induced absorption shows that the transmission recovery observed after irradiation is compatible with the reaction of radiation-induced defects with H-related (H-2, H2O) species diffusing in the amorphous matrix