scholarly journals EPR-Investigation of Irradiated Imported Foodstuffs and Parameters of EPR Signals

2012 ◽  
Vol 14 (4) ◽  
pp. 343 ◽  
Author(s):  
T. Seredavina ◽  
O. Stakhov ◽  
N. Sushkova ◽  
A. Nurkasymova
Keyword(s):  
Dose Range ◽  
Radiation Sterilization ◽  
Paramagnetic Resonance ◽  
Wide Range ◽  
Radiation Induced ◽  
Electron Paramagnetic Resonance Technique ◽  
Probable Impact ◽  
Gamma Irradiated ◽  
Electron Paramagnetic ◽  
Selection Of

Study by EPR (electron paramagnetic resonance) technique of a wide range of food products imported to Kazakhstan and of analogous domestic foodstuffs has been carried out in order to develop a methodic that would make it possible to control the fact of radiation sterilization of food. Elaborated method of sample preparing for EPR-study included dividing into components, removing moisture by drying or lyophilizing then grinding till dimensional work fraction. Selection of optimal conditions for spectra recording and algorithm of spectra treatment enabled authors to allocate correctly initial EPR-signals and to obtain information on shape, intensities and parameters. Model gamma-irradiations of the initial whole products with subsequent study of prepared EPR-specimen have been carried out. Influence of irradiation on the intensities of EPR-signals and possible changes of EPR-characteristics have been studied in dose range (0.1-25) kGy. EPR-signals of free radicals (FR) of radiation origin were obtained from the EPR-spectra of gamma-irradiated delicious fruits, citrus, vegetables and others. Nonmonotonous dependences of FR concentration on a dose, along with linear ones were observed. Intensities of initial signals and of radiation-induced ones are much higher in solid components, than in pulp, dependences on dose are more close to linearity, which can be used in some cases for retrospective EPR-dosimetry. The obtained results can be explained taking into account specificities of the studied objects, and probable impact of radiochemical reactions of the irradiated water products with radicals formed in substances of foodstuff at irradiation.

scholarly journals Facile Synthesis of L-Cysteine Functionalized Graphene Quantum Dots as a Bioimaging and Photosensitive Agent

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1879
Author(s):  
Mila Milenković ◽  
Aleksandra Mišović ◽  
Dragana Jovanović ◽  
Ana Popović Bijelić ◽  
Gabriele Ciasca ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Gamma Irradiation ◽  
Hela Cells ◽  
Graphene Quantum Dots ◽  
Morphological Properties ◽  
Paramagnetic Resonance ◽  
Chemical Reagents ◽  
Amino Amide ◽  
Gamma Irradiated ◽  
Electron Paramagnetic

Nowadays, a larger number of aggressive and corrosive chemical reagents as well as toxic solvents are used to achieve structural modification and cleaning of the final products. These lead to the production of residual, waste chemicals, which are often reactive, cancerogenic, and toxic to the environment. This study shows a new approach to the modification of graphene quantum dots (GQDs) using gamma irradiation where the usage of reagents was avoided. We achieved the incorporation of S and N atoms in the GQD structure by selecting an aqueous solution of L-cysteine as an irradiation medium. GQDs were exposed to gamma-irradiation at doses of 25, 50 and 200 kGy. After irradiation, the optical, structural, and morphological properties, as well as the possibility of their use as an agent in bioimaging and photodynamic therapy, were studied. We measured an enhanced quantum yield of photoluminescence with the highest dose of 25 kGy (21.60%). Both S- and N-functional groups were detected in all gamma-irradiated GQDs: amino, amide, thiol, and thione. Spin trap electron paramagnetic resonance showed that GQDs irradiated with 25 kGy can generate singlet oxygen upon illumination. Bioimaging on HeLa cells showed the best visibility for cells treated with GQDs irradiated with 25 kGy, while cytotoxicity was not detected after treatment of HeLa cells with gamma-irradiated GQDs.

scholarly journals DeerLab: a comprehensive software package for analyzing dipolar electron paramagnetic resonance spectroscopy data

2020 ◽  
Vol 1 (2) ◽  
pp. 209-224 ◽  
Author(s):  
Luis Fábregas Ibáñez ◽  
Gunnar Jeschke ◽  
Stefan Stoll
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Software Package ◽  
Method Development ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Global Analysis ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Least Squares Fit ◽  
Wide Range ◽  
Electron Paramagnetic

Abstract. Dipolar electron paramagnetic resonance (EPR) spectroscopy (DEER and other techniques) enables the structural characterization of macromolecular and biological systems by measurement of distance distributions between unpaired electrons on a nanometer scale. The inference of these distributions from the measured signals is challenging due to the ill-posed nature of the inverse problem. Existing analysis tools are scattered over several applications with specialized graphical user interfaces. This renders comparison, reproducibility, and method development difficult. To remedy this situation, we present DeerLab, an open-source software package for analyzing dipolar EPR data that is modular and implements a wide range of methods. We show that DeerLab can perform one-step analysis based on separable non-linear least squares, fit dipolar multi-pathway models to multi-pulse DEER data, run global analysis with non-parametric distributions, and use a bootstrapping approach to fully quantify the uncertainty in the analysis.

Radiation-induced defects in montebrasite: An electron paramagnetic resonance study of O – hole and Ti3+ electron centers

2020 ◽  
Vol 105 (7) ◽  
pp. 1051-1059
Author(s):  
José R. Toledo ◽  
Raphaela de Oliveira ◽  
Lorena N. Dias ◽  
Mário L.C. Chaves ◽  
Joachim Karfunkel ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electron Irradiation ◽  
Color Centers ◽  
Hydroxyl Groups ◽  
Γ Irradiation ◽  
Paramagnetic Resonance ◽  
Radiation Induced ◽  
Induced Defects ◽  
Electron Paramagnetic ◽  
Hole Centers

Abstract Montebrasite is a lithium aluminum phosphate mineral with the chemical formula LiAlPO4(Fx,OH1–x) and considered a rare gemstone material when exhibiting good crystallinity. In general, montebrasite is colorless, sometimes pale yellow or pale blue. Many minerals that do not have colors contain hydroxyl ions in their crystal structures and can develop color centers after ionization or particle irradiation, examples of which are topaz, quartz, and tourmaline. The color centers in these minerals are often related to O− hole centers, where the color is produced by bound small polarons inducing absorption bands in the near UV to the visible spectral range. In this work, colorless montebrasite specimens from Minas Gerais state, Brazil, were investigated by electron paramagnetic resonance (EPR) for radiation-induced defects and color centers. Although γ irradiation (up to a total dose of 1 MGy) did not visibly modify color, a 10 MeV electron irradiation (80 MGy) induced a pale greenish-blue color. Using EPR, O− hole centers were identified in both γ- or electron-irradiated montebrasite samples showing superhyperfine interactions with two nearly equivalent 27Al nuclei. In addition, two different Ti3+ electron centers were also observed. From the γ irradiation dose dependency and thermal stability experiments, it is concluded that production of O− hole centers is limited by simultaneous creation of Ti3+ electron centers located between two equivalent hydroxyl groups. In contrast, the concentration of O− hole centers can be strongly increased by high-dose electron irradiation independent of the type of Ti3+ electron centers. From detailed analysis of the EPR angular rotation patterns, microscopic models for the O− hole and Ti3+ electron centers are presented, as well as their role in the formation of color centers discussed and compared to other minerals.

Ultra-broadband EPR spectroscopy in field and frequency domains

2018 ◽  
Vol 20 (22) ◽  
pp. 15528-15534 ◽  
Author(s):  
P. Neugebauer ◽  
D. Bloos ◽  
R. Marx ◽  
P. Lutz ◽  
M. Kern ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Magnetic Properties ◽  
Epr Spectroscopy ◽  
Paramagnetic Resonance ◽  
Powerful Technique ◽  
Electronic And Magnetic Properties ◽  
Wide Range ◽  
Frequency Domains ◽  
Electron Paramagnetic

Electron paramagnetic resonance (EPR) is a powerful technique to investigate the electronic and magnetic properties of a wide range of materials.

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