Paramagnetic Resonance Hyperfine Structure of the Free Radical (SO3)2NO=

1953 ◽  
Vol 21 (10) ◽  
pp. 1905-1906 ◽  
Author(s):  
B. Smaller ◽  
E. L. Yasaitis
Keyword(s):  
Free Radical ◽  
Hyperfine Structure ◽  
Paramagnetic Resonance

Influence of particle size on the paramagnetic components of kaolins from different origins

Clay Minerals ◽  
2012 ◽  
Vol 47 (4) ◽  
pp. 539-557 ◽  
Author(s):  
N. Worasith ◽  
B. A. Goodman
Keyword(s):  
Particle Size ◽  
Free Radical ◽  
Hyperfine Structure ◽  
Structural Changes ◽  
The Other ◽  
Epr Spectra ◽  
Paramagnetic Resonance ◽  
Oh Groups ◽  
Size Fractions ◽  
Particle Size Fractions

AbstractElectron paramagnetic resonance (EPR) spectra of different particle size fractions of four kaolins from diverse sources in North America, Europe and Asia have been investigated in order to characterize their paramagnetic properties and heterogeneity. There were major differences in the sources of the EPR signals from transition metals; V and Mn were structural, Fe was both structural and as associated oxides, and Cu was in the form of an adsorbed ion. The radiation-induced free radical signals commonly known as the A- and B-centres were observed in three of the deposits; however, in addition to the previously reported 27Al hyperfine structure associated with the B-centre, we also observed much smaller 27Al hyperfine structure on the g┴ feature of the A-centre. The other kaolin sample produced four free radical signals that have not previously been reported in kaolins. Each had substantial 1H hyperfine splitting; three are interpreted as corresponding to defect centres associated with Si-OH groups, and the other to a Si hole surrounded by protonated O atoms. The EPR spectra changed progressively with particle size, and measurements on the Asian specimens after grinding showed major differences in the Fe3+ signals from the same particle size fractions separated from the natural samples, thus supporting previous reports that grinding results in major structural changes in the minerals.

Phosphorus hyperfine structure in the electronic spectrum of the HPCl free radical

2004 ◽  
Vol 121 (3) ◽  
pp. 1405-1411 ◽  
Author(s):  
Brandon S. Tackett ◽  
Dennis J. Clouthier ◽  
Allan G. Adam ◽  
Scott A. Shepard
Keyword(s):  
Free Radical ◽  
Hyperfine Structure ◽  
Electronic Spectrum

Investigation of Antioxidant Activity of Pomegranate Juices by Means of Electron Paramagnetic Resonance and UV-Vis Spectroscopy

2015 ◽  
Vol 98 (4) ◽  
pp. 866-870 ◽  
Author(s):  
Violetta Kozik ◽  
Krystyna Jarzembek ◽  
Agnieszka Jędrzejowska ◽  
Andrzej Bąk ◽  
Justyna Polak ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Free Radical ◽  
Epr Spectroscopy ◽  
Antioxidant Properties ◽  
Free Radical Scavenger ◽  
Pomegranate Juice ◽  
Radical Scavenger ◽  
Paramagnetic Resonance ◽  
Vis Spectroscopy ◽  
Electron Paramagnetic

Abstract Pomegranate fruit (Punica granatum L.) is a source of numerous phenolic compounds, and it contains flavonoids such as anthocyanins, anthocyanidins, cyanidins, catechins and other complexes of flavonoids, ellagitannins, and hydrolyzed tannins. Pomegranate juice shows antioxidant, antiproliferative, and anti-atherosclerotic properties. The antioxidant capacity (TEAC) of the pomegranate juices was measured using electron paramagnetic resonance (EPR) spectroscopy and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) as a source of free radicals, and the total phenolic (TP) content was measured using UV-Vis spectroscopy. All the examined pomegranate juices exhibited relatively high antioxidant properties. The TEAC values determined by means of EPR spectroscopy using Trolox (TE) as a free radical scavenger were in the range of 463.12 to 1911.91 μmol TE/100 mL juice. The TP content measured by the Folin-Ciocalteu method, using gallic acid (GA) as a free radical scavenger, widely varied in the investigated pomegranate juice samples and ranged from 1673.62 to 5263.87 mg GA/1 L juice. The strongest antioxidant properties were observed with the fresh pomegranate juices obtained from the fruits originating from Israel, Lebanon, and Azerbaijan. Correlation analysis of numerical data obtained by means of EPR spectroscopy (TEAC) and UV-Vis spectroscopy (TP) gave correlation coefficient (r) = 0.90 and determination coefficient (r2) = 0.81 (P <0.05).

Paraquat-induced lung injury: prevention by N-tert-butyl-alpha-phenylnitrone, a free-radical spin-trapping agent

1992 ◽  
Vol 262 (2) ◽  
pp. L147-L152
Author(s):  
T. Sata ◽  
E. Kubota ◽  
H. P. Misra ◽  
M. Mojarad ◽  
H. Pakbaz ◽  
...  
Keyword(s):  
Free Radical ◽  
Lung Injury ◽  
Guinea Pig ◽  
Weight Ratio ◽  
Spin Trapping ◽  
Lung Weight ◽  
Paramagnetic Resonance ◽  
Arterial Perfusion ◽  
Tert Butyl ◽  
Trapping Agent

The herbicide paraquat causes lung injury that is believed to be oxygen-radical mediated. To further characterize this injury and explore new methods of preventing it, we used the spin-trapping agent N-tert-butyl-alpha-phenylnitrone (PBN) to identify the paraquat radical in lung tissue and to reduce the injury resulting from the subsequent generation of reactive oxygen species. The formation of a paraquat free radical by guinea pig lung was detected under anaerobic conditions by electron paramagnetic resonance spectrometry. Infused (25, 50, or 100 mg/kg) into guinea pig lungs (perfused at constant flow with Krebs solution containing 4% bovine serum albumin and ventilated with 95% O2-5% CO2), paraquat produced dose-dependent increases in peak airway pressure (Paw), mean pulmonary arterial perfusion pressure (Ppa), and wet-to-dry (W/D) lung weight ratio. At 100 mg/kg, paraquat increased Paw by 589.6 +/- 59.8% (mean +/- SE, n = 8) and W/D ratio from 5.33 +/- 0.07 to 6.29 +/- 0.11 (P less than 0.001). Pulmonary vascular leak index increased from 0.40 +/- 0.09 to 1.96 +/- 0.45 (P less than 0.02), without changes in pulmonary microvascular pressure. Perfusate concentrations of thromboxane B2 and 6-ketoprostaglandin F1 alpha increased, but indomethacin did not reduce the injury. PBN (2.3 mM) markedly attenuated all evidence of lung injury, which was also reduced by catalase, mannitol, ethanol, and vitamin E.(ABSTRACT TRUNCATED AT 250 WORDS)

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