scholarly journals Kinetic analysis of mechanoradical formation during the mechanolysis of dextran and glycogen

2017 ◽  
Vol 13 ◽  
pp. 1174-1183 ◽  
Author(s):  
Naoki Doi ◽  
Yasushi Sasai ◽  
Yukinori Yamauchi ◽  
Tetsuo Adachi ◽  
Masayuki Kuzuya ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Electron Spin Resonance ◽  
Room Temperature ◽  
Particle Diameter ◽  
Helical Structure ◽  
Esr Spectra ◽  
Radical Concentration ◽  
Maximum Value ◽  
Spin Resonance ◽  
Branched Structure

A detailed electron spin resonance (ESR) analysis of mechanically induced free radicals (mechanoradicals) formation of glucose-based polysaccharides, dextran (Dx) and glycogen (Gly) was performed in comparison with amylose mechanoradicals. The ESR spectra of the samples mechanically fractured at room temperature were multicomponent. The radical concentration of Dx and Gly mechanoradicals gradually decreased during vibratory milling after reaching the maximum value. Although the molecular weight of Dx or the particle diameter of Gly steeply diminished until reaching the each maximum value of radical concentration, after that the molecular weight or the particle diameter slowly decreased. These results suggested that Dx and Gly mechanoradicals might be more unstable than amylose radicals possessing an intramolecular helical structure due to the branched structure.

scholarly journals A new method for determining the concentration of vanadyl ions in clays

2011 ◽  
Vol 62 (2) ◽  
pp. 181-186 ◽  
Author(s):  
Pavle Premović ◽  
Budimir Ilić ◽  
Dragan Đorđević
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Room Temperature ◽  
Esr Spectra ◽  
New Method ◽  
Simple Method ◽  
Routine Work ◽  
Spin Resonance ◽  
Resonance Data ◽  
Electron Spin Resonance Data

A new method for determining the concentration of vanadyl ions in claysA novel and simple method for quantitatively determining the concentration of vanadyl ions in clays using electron spin resonance data has been developed. Several vanadyl standards with concentrations between 200-1000 ppm were prepared in a mixture of glycerol and kaolinite (KGa-2). The anisotropic electron spin resonance (ESR) spectra were recorded at room temperature, and the specific intensity of the line (attributed to nuclear spin m = -5/2||) was determined. For vanadyl concentrations between 50 ppm and 200 ppm, the standards must be prepared by mixing kaolinite with known vanadyl content (FBT2A-03) and kaolinite (GB1) containing no vanadyl. The method is applicable without modification to other clays and clay-rich sediments containing vanadyl ions. The whole procedure is very suitable for routine work.

scholarly journals Electron Spin Resonance Measurement with Microinductor on Chip

2011 ◽  
Vol 2011 ◽  
pp. 1-3
Author(s):  
Akio Kitagawa
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Room Temperature ◽  
Near Field ◽  
Esr Spectra ◽  
Ethanol Solution ◽  
Spin Resonance ◽  
On Chip ◽  
Processing Circuit ◽  
Probe Head

The detection of radicals on a chip is demonstrated. The proposed method is based on electron spin resonance (ESR) spectroscopy and the measurement of high-frequency impedance of the microinductor fabricated on the chip. The measurement was by using a frequency sweep of approximately 100 MHz. The ESR spectra of di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH) dropped on the microinductor which is fabricated with CMOS 350-nm technology were observed at room temperature. The volume of the DPPH ethanol solution was 2 μL, and the number of spins on the micro-inductor was estimated at about 1014. The sensitivity is not higher than that of the standard ESR spectrometers. However, the result indicates the feasibility of a near field radical sensor in which the microinductor as a probe head and ESR signal processing circuit are integrated.

ELECTRON SPIN RESONANCE OF Fe+3 IN CORDIERITE

1966 ◽  
Vol 44 (11) ◽  
pp. 2749-2755 ◽  
Author(s):  
N. E. Hedgecock ◽  
S. C. Chakravartty
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Room Temperature ◽  
Esr Spectra ◽  
Orthorhombic Symmetry ◽  
Zero Field ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Spin Resonance

ESR spectra of Fe+3 located at one of the aluminium sites in cordierite have been investigated at X- and K-band frequencies at room temperature. The spectra exhibit large zero-field splitting and have been fitted to a spin Hamiltonian of orthorhombic symmetry, having constants b20 = 14.6 ± 0.1 kG, b22 = 8.5 ± 0.1 kG, and isotropic g = 2.004 ± 0.002.

Electron spin resonance of spin trapped radicals in γ-irradiated polycrystalline dipeptides. Chromatographic separation of radicals

1982 ◽  
Vol 60 (12) ◽  
pp. 1480-1485 ◽  
Author(s):  
Keisuke Makino ◽  
Peter Riesz
Keyword(s):  
High Performance Liquid Chromatography ◽  
Electron Spin Resonance ◽  
Ring Opening ◽  
High Performance ◽  
Room Temperature ◽  
Spin Trap ◽  
Esr Spectra ◽  
Spin Resonance ◽  
Carboxyl Terminal ◽  
Deamination Reaction

Polycrystalline dipeptides (glycyl-glycine, glycyl-L-valine, glycyl-L-leucine, L-alanyl-glycine, and L-prolyl-L-alanine) were γ-irradiated at room temperature in the absence of air. Subsequently they were dissolved in aqueous solutions containing 2-methyl-2-nitrosopropane as the spin trap. From the esr spectra of the nitroxide radicals separated by high-performance liquid chromatography, structural assignments of the radicals were made. For glycyl peptides, H-abstraction from the α-carbon atoms of the carboxyl terminal residues and from the side-chains were observed. For L-alanyl-glycine, H-abstraction from the glycyl residue and the formation of the deamination radical could be shown to occur. For L-prolyl-L-alanine, the ring opening (deamination) reaction, decarboxylation and H-abstraction from the C-terminal a-carbon were seen.

Structure of radicals produced by γ-radiolysis. Part 4. Adamantane matrices doped with various 5-membered heterocyclic molecules

1976 ◽  
Vol 54 (12) ◽  
pp. 1971-1984 ◽  
Author(s):  
D. L. Winters ◽  
A. Campbell Ling
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Room Temperature ◽  
Esr Spectra ◽  
Heterocyclic Molecules ◽  
First Derivative ◽  
X Band ◽  
Spin Resonance ◽  
Spin Center ◽  
Esr Spectrometry

The effects of γ-adiolysis at room temperature on adamantane and adamantane-d16 matrices doped with 5-membered heterocyclic molecules has been examined by X-band electron spin resonance (esr) spectrometry. Radical structures formed from heterocyclic solute molecules are discussed and tentative assignments made for 2-methyl-, 3-methyl-, and 2,5-dimethylthiophene, 2-methyl-, and 2,5-dimethylfuran. Discussion of possible radical structures derived from furan, tetrahydrofuran, 2-methyl- and 3-methyltetrahydrofuran, 2,5-dihydrofuran, and 4,5-dihydro-2-methylfuran, is included, but unambiguous assignments of structure cannot be made for these compounds from the esr data obtained. Other molecules examined included thiophene, pyrrole, and 1-methyl- and 1,2,5-trimethylpyrrole. For these latter molecules, experimentally obtained first derivative X-band esr spectra were too poorly resolved to allow rational discussion of possible structures. It was noted that perdeuterated adamantane matrices provided superior resolution for esr spectra derived from radicals with a delocalized spin center such as allyl or allenyl species.

scholarly journals Force detection of high-frequency electron spin resonance near room temperature using high-power millimeter-wave source gyrotron

2021 ◽  
Vol 118 (2) ◽  
pp. 022407
Author(s):  
Hideyuki Takahashi ◽  
Yuya Ishikawa ◽  
Tsubasa Okamoto ◽  
Daiki Hachiya ◽  
Kazuki Dono ◽  
...  
Keyword(s):  
Electron Spin Resonance ◽  
Millimeter Wave ◽  
Electron Spin ◽  
High Power ◽  
High Frequency ◽  
Room Temperature ◽  
Force Detection ◽  
Wave Source ◽  
Spin Resonance ◽  
Millimeter Wave Source

FREE RADICALS OF BIOLOGICAL INTEREST: PART II. ELECTRON SPIN RESONANCE (ESR) SPECTRA OF 2537 A IRRADIATED AMINO ACIDS

1967 ◽  
Vol 45 (12) ◽  
pp. 1831-1839 ◽  
Author(s):  
W. F. Forbes ◽  
P. D. Sullivan
Keyword(s):  
Amino Acids ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Hydrogen Abstraction ◽  
Esr Spectra ◽  
Side Chain ◽  
Biological Interest ◽  
Spin Resonance ◽  
Cyclohexadienyl Radical ◽  
Secondary Radical

Polycrystalline amino acids, when irradiated with 2537 Å light, afford a variety of electron spin resonance signals. These signals are generally stable at room temperature for relatively long periods of time. For a number of the spectra obtained, there is evidence that more than one radical species contributes to the observed spectra. The signals obtained frequently differ from those obtained on exposure to ionizing radiation. The postulated species formed can often be visualized as being formed by effective hydrogen abstraction from the alkyl-substituted tertiary carbon atom or from the —OH, —SH or —NH group contained in the side chain. For L-phenylalanine a secondary radical is obtained, which is ascribed to a cyclohexadienyl radical.

Electron spin resonance observations of photochemically generated contact ammonium ion-pairs of fluoro-substituted ketones

1979 ◽  
Vol 57 (5) ◽  
pp. 600-602 ◽  
Author(s):  
K. S. Chen ◽  
T. Foster ◽  
J. K. S. Wan
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Ion Pairs ◽  
Esr Spectra ◽  
Ammonium Ion ◽  
Spin Resonance ◽  
Photochemical Systems

Contact radical ion-pairs of ammonium and fluoro-substituted ketones were generated in photochemical systems and their here-to-fore elusive esr spectra were characterized.

Magnetic resonance studies of metal–olefin complexes. I. Electron spin resonance spectra of γ-irradiated silver perchlorate cycloalkene complexes

1970 ◽  
Vol 48 (17) ◽  
pp. 2740-2744 ◽  
Author(s):  
D. R. Gee ◽  
K. E. Russell ◽  
J. K. S. Wan
Keyword(s):  
Electron Spin Resonance ◽  
Magnetic Resonance ◽  
Spin Density ◽  
Room Temperature ◽  
Paramagnetic Species ◽  
Magnetic Resonance Studies ◽  
Silver Perchlorate ◽  
Spin Resonance ◽  
The Stability ◽  
Polycrystalline Silver

Paramagnetic species have been detected in γ-irradiated polycrystalline silver perchlorate – cycloalkene complexes at room temperature and identified as Ag+ cycloalkenyl radicals, with spin density on Ag decreasing from 4.6 to 1.5% with increasing size of the cycloalkenyl ring. The extent of the spin density on Ag increases with the stability of the parent complexes.

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