Search results for " ESR"
showing 10 items of 46 documents
Detection of Irradiated Food and Evaluation of the Given Dose by Electron Spin Resonance, Thermoluminescence, and Gas Chromatographic/Mass Spectromet…
2018
Abstract The treatment of food with ionizing radiation, at doses lower than 10 kGy, is a preservation technology, which can be used to reduce food spoilage due to microorganisms and to decrease insect infestation, enhancing, in the same time, the hygienic quality, extending the shelf life of food itself. In order to increase the general consumer acceptance and accordingly to facilitate the commercialization and trade of irradiated food, the European Committee for Standardization (CEN) validated reliable analytical techniques to identify irradiated foodstuffs for legal control purposes, distinguished in Chemical, Physical, and Microbiological ones, depending on the characteristics of marker …
CHARACTERIZATION OF THE GAMMA DOSE COMPONENT IN THE NEUTRON FIELD OF A BNCT IRRADIATION FACILITY
2017
At the University of Pavia, a neutron irradiation facility has been constructed for preclinical in vitro and in vivo studies for BNCT. The facility is a wide channel (40 x 20 x 100 cm3) inside the graphite Thermal Column of the 250 KW research reactor TRIGA Mark II. The neutron field consists in a thermal component ranging from about 1010 and 109 cm-2s-1 along the longitudinal axis of the channel and it is uniform within 10% along the transversal axes. The fast neutron contamination (En > 1.58 keV) is more than 2 orders of magnitude lower. The gamma background coming from the core has been reduced with a 20 cm thick bismuth shield, however in the facility a gamma component is still prese…
Neutron dosimetry by means of electron spin resonance (ESR) tecnique
2012
Along with the Neutron Capture Therapy (NCT) development and with the use of thermal neutrons for radiotherapeutic purposes, many efforts have been devoted to the beam characterization in order to optimize the therapy procedures. Reliable dosimetric measurements should be able to determine the various components (neutronic and photonic) of the mixed beam usually employed for therapy. We have studied the effect of the additive such as gadolinium and 10B-boric acid on the neutron sensitivity of alanine ESR dosimeters exposed to a gamma and mixed (n, gamma) field mainly composed by thermal neutrons. We have chosen both this additive nuclei because of their very high capture cross section to th…
EPR/alanine dosimetry for two therapeutic proton beams
2016
Abstract In this work the analysis of the electron paramagnetic resonance (EPR) response of alanine pellets exposed to two different clinical proton beams employed for radiotherapy is performed. One beam is characterized by a passive delivery technique and is dedicated to the eyes treatment (OPTIS2 beam line). Alanine pellets were irradiated with a 70 MeV proton beam corresponding to 35 mm range in eye tissue. We investigated how collimators with different sizes and shape used to conform the dose to the planned target volume influence the delivered dose. For this purpose we performed measurements with varying the collimator size (Output Factor) and the results were compared with those obtai…
ESR dosimeter material properties of phenols compound exposed to radiotherapeutic electron beams
2017
Abstract There is a need for a sensitive dosimeter using Electron Spin Resonance spectroscopy for use in medical applications, since non-destructive read-out and dose archival could be achieved with this method. This work reports a systematic ESR investigation of IRGANOX ® 1076 exposed to clinical electron beams produced by a LINAC used for radiation therapy treatments. Recently, dosimetric features of this material were investigated for irradiation with 6 0Co γ -photons and neutrons in both pellet and film shape and have been found promising thanks to their high efficiency of radiation-matter energy transfer and radical stability at room temperature. Here the analysis of the dosimetric fea…
Multitechnique Analysis of the Hydration in Three Different Copper Paddle-Wheel Metal-Organic Frameworks
2019
The structural instability in a humid environment of the majority of metal-organic frameworks (MOFs) is a challenging obstacle for their industrial-scale development. Recently, two water-resistant MOFs have been synthetized, STAM-1 and STAM-17-OEt. They both contain copper paddle wheels, like the well-known water-sensitive HKUST-1, but different organic linkers. The crystal lattice of both the MOFs undergoes a phase transition upon interaction with water molecules. Their unusual flexibility allows the controlled breaking of some interpaddle wheel Cu-O interactions in the so-called crumple zones, with a mechanism called hemilability, which is considered to have a crucial role for the stabili…
Pulsed EPR analysis of tooth enamel samples exposed to UV and gamma radiations
2010
Pulsed EPR analysis of tooth enamel samples exposed to UV and gamma-radiations
2011
Abstract The electron paramagnetic resonance (EPR) spectroscopy is widely applied for retrospective dosimetric purposes by means of quantitative detection of radicals in tooth enamel and bone samples. In this work we report a study by cw and pulsed EPR on two samples of human tooth enamel respectively irradiated by UV (254 nm) and γ-exposed. The continuous wave (cw) EPR spectra have shown the usual presence in both samples of two types of CO 2 − radicals, with axial and orthorombic g tensors. We have obtained the electron spin echo detected EPR (ED-EPR) spectra at 80 K of the two samples, and we have shown that they are suitable to mark the difference between the effects produced by the dif…
Irradiation detection of herbal ingredients used in plant food supplements by Electron Spin Resonance on samples pre-treated with alcoholic extraction
2020
Abstract This study aimed to verify the applicability of the EN 1787 method for the detection of irradiation in herbal ingredients used in Plant Food Supplements (PFSs). In matrices such as herbs and spices the main limit of the method is the presence of intrinsic radicals responsible for spurious signals leading to complex ESR spectra. To overcome this limit, before ESR measurement a treatment with alcohol has been proposed (Delincee and Soika, 2002; Ahn et al., 2012, 2014). As reported in the literature, this treatment is expected to reduce/eliminate the confounding signals so that the samples may be correctly classified. In this study the efficacy of the pre-treatment was tested on raw h…