Detection of Free Radicals in Electron Beam-Irradiated Mucuna pruriens (L. DC.) Seeds by Electron Spin Resonance

2007 ◽  
Vol 13 (4) ◽  
pp. 249-257 ◽  
Author(s):  
R. Bhat ◽  
K.R. Sridhar
Keyword(s):  
Electron Beam ◽  
Free Radicals ◽  
Seed Coat ◽  
Signal Intensity ◽  
Electron Beam Irradiation ◽  
Linear Increase ◽  
Mucuna Pruriens ◽  
Beam Irradiation ◽  
Satellite Peak ◽  
Spin Resonance

Electron spin resonance (ESR) spectroscopy was employed to detect free radicals in raw Mucuna pruriens (velvet bean) seeds after electron beam irradiation (Microtron source: 0, 2.5, 5, 7.5, 10, 15 and 30 kGy) and conventional processing (roasting, powdering and cooking). The ESR signal of irradiated seeds (g=2.0055±0.0001) was more prominent in the seed coat than cotyledon. Seed coat of irradiated samples showed dose-dependent linear increase of this signal (g = 2.0055) accompanied by a weak triplet (satellite peak; aH = 3 mT) produced exclusively by radiolysis and could be used as an indication of successful irradiation. Irradiated cotyledon portion devoid of satellite peak (triplet) showed a linear increase in signal intensity up to 10 kGy with a sharp decline at higher doses (15 and 30kGy). Stability of radiation-induced ESR signals after 6 months of storage (25 ± 1°C) revealed the presence of a weak triplet with a substantial loss of signal intensity. Thermal effects such as roasting and powdering of seeds increased the signal intensity (g = 2.0055) similar to or in greater proportion than irradiation. Phenolics in seeds, which contribute significantly to detect free radicals in vegetative parts of a plant showed a waning trend in seed coat, while it was vice versa in cotyledon. Textural studies revealed significant loss in firmness after irradiation (p<0.05), which might favour in minimising the cooking time. Results of the present study might help to divulge the beneficial effects of application of electron beam irradiation technology as a better alternative to fumigants in seed preservation for safety and quarantine purposes.

Electron Spin Resonance Studies on Electron Beam Irradiated Carbon Nanotubes Dispersed in Styrene-Isoprene-Styrene Block Copolymer

2004 ◽  
Vol 851 ◽  
Author(s):  
Mircea Chipara ◽  
Wendland Beezhold ◽  
Timothy Webb ◽  
Jeffrey M. Zaleski ◽  
Kristina Stephenson ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electron Beam ◽  
Free Radicals ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Electron Beam Irradiation ◽  
Electron Bombardment ◽  
Beam Irradiation ◽  
Spin Resonance ◽  
Radiation Induced

ABSTRACTElectron spin resonance investigations on the effect of electron bombardment of nanocomposites obtained by dispersing carbon nanotubes within styrene-isoprene-styrene are reported. The experimental results revealed the absence of radiation-induced free radicals and a negligible effect of electron beam irradiation on the electron spin resonance spectra of carbon nanotubes.

Influence of Electron Beam Irradiation on The Nucleation of Fine Water Drops on Misted Silicate (SiO2) Glass

1998 ◽  
Vol 540 ◽  
Author(s):  
K. Oguri ◽  
K. Sato ◽  
T. Izumi ◽  
A. Tonegawa ◽  
K. Takayama ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Surface Condition ◽  
Active Surface ◽  
Esr Spectra ◽  
Dangling Bond ◽  
Beam Irradiation ◽  
Nucleation Frequency ◽  
Spin Resonance ◽  
Water Drops

AbstractBy using an electron beam irradiation, reproducible active surface condition of misting can be obtained on the silicate glass. Since an electron beam irradiation activates the SiO2 surface, it controls and enhances the nucleation frequency of fine water drops. The dangling bond is one of reasons to activate the surface condition. Based on the results of electron spin resonance (ESR) spectra, the electron beam irradiation increases the density of E'-center on the surface.

Hot Set Characterization of Electron Beam Irradiated-Copper (II) Oxide Added LDPE Composites under Acidic Aging

2015 ◽  
Vol 786 ◽  
pp. 63-67
Author(s):  
Tiam Ting Tee ◽  
Soo Tueen Bee ◽  
Tin Sin Lee ◽  
Chantara Thevy Ratnam ◽  
Haraveen Kaur Jogindar Singh
Keyword(s):  
Electron Beam ◽  
Free Radicals ◽  
High Temperature ◽  
Electron Beam Irradiation ◽  
Static Load ◽  
Beam Irradiation ◽  
Duration Time ◽  
The Matrix ◽  
Oxide Particles ◽  
Ldpe Composites

In this research study, the effect of aging duration time and electron beam irradiation dosages on the hot set results of copper (II) oxide added LDPE composites have been investigated. The addition of copper (II) oxide particles in LDPE matrix has significantly reduced the formation of crosslinking networks in LDPE matrix by blocking the mobility of free radicals generated by electron beam irradiation. At lower irradiation dosages (< 100 kGy), all the copper (II) oxide added LDPE composites were immediately failed the hot set test when subjected to static load of 20 N/cm2 under high temperature. Besides, the occurrence of copper (II) oxide particles in LDPE matrix also reduced the matrix continuities of copper (II) oxide added LDPE composites and caused the matrix resistance ability of LDPE matrix to be decreased. The increasing of irradiation dosages has significantly delayed the failing time of all LDPE composites when under static load at high temperature. This is because the increasing of electron beam irradiation could further induce the generation of free radicals to form higher degree of crosslinking networks in LDPE matrix. At higher irradiation dosage up to 250 kGy, the pristine LDPE was observed able to withstand the applied static load under high temperature more than 15 minutes. This is due to higher degree of crosslinking networks formed in LDPE matrix could effectively restrict the mobility of LDPE chains under static load and thus delay the failing of sampels. When the aging duration time increased from 4 days to 14 days, the resistance ability of all LDPE has been significantly weakened due to the occurrence of chain scissioning process in LDPE matrix by delaying the failing time of samples.

Methods to Monitor and Improve the Performance of Specimen Holders for Transmission Electron Cryomicroscopy

1996 ◽  
Vol 54 ◽  
pp. 454-455
Author(s):  
B. L. Armbruster ◽  
B. Kraus ◽  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Beam Irradiation ◽  
Quality Of Data ◽  
Electron Cryomicroscopy ◽  
Thermal Equilibration ◽  
Transmission Electron ◽  
Electron Microscopes

One goal in electron microscopy of biological specimens is to improve the quality of data to equal the resolution capabilities of modem transmission electron microscopes. Radiation damage and beam- induced movement caused by charging of the sample, low image contrast at high resolution, and sensitivity to external vibration and drift in side entry specimen holders limit the effective resolution one can achieve. Several methods have been developed to address these limitations: cryomethods are widely employed to preserve and stabilize specimens against some of the adverse effects of the vacuum and electron beam irradiation, spot-scan imaging reduces charging and associated beam-induced movement, and energy-filtered imaging removes the “fog” caused by inelastic scattering of electrons which is particularly pronounced in thick specimens.Although most cryoholders can easily achieve a 3.4Å resolution specification, information perpendicular to the goniometer axis may be degraded due to vibration. Absolute drift after mechanical and thermal equilibration as well as drift after movement of a holder may cause loss of resolution in any direction.

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