Search results for "sperimentale"
showing 10 items of 938 documents
Electron Spin Resonance dosimetry using organic compounds (alanine and ammonium tartrate) for mixed neutron-gamma fields
2016
Alongside with the development of Neutron Capture Therapy (NCT) and the use of thermal neutrons for radiotherapeutic purposes, many efforts have been devoted to the characterization of the beam in order to optimize therapy procedures. Reliable dose measurements should be able to determine the various (neutrons and photonic) components of the mixed beam usually employed for therapy. This paper studies the effect of additives such as boric and gadolinium nuclei on the sensitivity of neutron organic (alanine and ammonium tartrate) dosimeters analyzed through Electron Spin Resonance (ESR) technique (Marrale, 2014). These dosimeters were exposed to a mixed (neutron-gamma) field mainly composed o…
Spin trapping as tool for investigating radiation induced free radicals in biologically active molecules
2017
Since from the second half of the last century the spin trapping has found wide applications in chemistry, biology and medicine [1]. Of particular interest are the studied of the free radicals induced in biologically active molecules, such as DNA and proteins, when they are exposed to ionizing radiation. Their characterization allows to investigate the radiation-induced primary processes inside living cells. Indeed, ionizing radiations produce many kinds of free radicals through direct action; radicals can be formed also by indirect actions. However, the direct detection of these radicals is hard to obtain as they have a too short lifetime and this makes difficult to record them by conventi…
Phenol compounds for Electron Spin Resonance dosimetry in gamma and neutron field
2016
The use of neutrons for cancer treatments has stimulated the research for beam characterization in order to optimize the therapy procedures in Neutron Capture Therapy (Altieri, 2008). Several research laboratories have shown an increasing interest aimed at extending the applicability of Electron Spin Resonance (ESR) dosimetry to radiotherapy with different types of radiation beams. In particular, ESR spectrometry provides absorbed dose measurements through the detection of the stable free radicals produced by ionizing radiations. The ESR dosimetric method has many advantages such as simple and rapid dose evaluation, the readout procedure is non-destructive, linear response of many organic a…
Phenol compounds for Electron Spin Resonance (ESR) dosimetry in gamma and neutron field
2015
The use of neutrons for cancer treatments has stimulated the research for beam characterization in order to optimize the therapy procedures in Neutron Capture Therapy (Altieri, 2008). Several research laboratories have shown an increasing interest aimed at extending the applicability of Electron Spin Resonance (ESR) dosimetry to radiotherapy with different types of radiation beams. In particular, ESR spectrometry provides absorbed dose measurements through the detection of the stable free radicals produced by ionizing radiations. The ESR dosimetric method has many advantages such as simple and rapid dose evaluation, the readout procedure is non-destructive, linear response of many organic a…
Do firms share the same functional form of their growth rate distribution? A statistical test
2014
We introduce a new statistical test of the hypothesis that a balanced panel of firms have the same growth rate distribution or, more generally, that they share the same functional form of growth rate distribution. We applied the test to European Union and US publicly quoted manufacturing firms data, considering functional forms belonging to the Subbotin family of distributions. While our hypotheses are rejected for the vast majority of sets at the sector level, we cannot rejected them at the subsector level, indicating that homogenous panels of firms could be described by a common functional form of growth rate distribution.
School-family relationship: a survey on the communicative and participatory methods of non-indigenous families
2022
Il complesso processo educativo basato sull’educazione delle giovani generazioni comporta un’assunzione di responsabilità da parte delle due principali agenzie educative: la famiglia e la scuola. Per la buona riuscita del processo educativo è necessario che tra le due agenzie ci sia un accordo implicito o esplicito sugli aspetti terminologici e concettuali, affinché si stabilisca una comprensione comune per gli interlocutori e si crei un contesto chiaro e trasparente che non lasci spazio a interpretazioni fallaci (Quaranta, 2019). I cambiamenti socioculturali hanno determinato un pluralismo culturale, religioso e nuove sfide tecnologiche e problematiche comunicative e partecipative (Pati, 2…
Scaffolding patterns of dialogic exchange in toddler classrooms
2021
The present study investigates how often episodes of dialogic exchange can be identified in educator–toddler interactions during play and emerging academic activities, what kind of scaffolding strategies educators use during the episodes of dialogic exchange and, ultimately, what kind of scaffolding patterns of dialogic exchange can be identified based on educators' use of scaffolding strategies. Educator–child interactions were video-recorded in seven European countries, in two toddler classrooms in each country. The video recordings of emerging academic and play activities were transcribed and analysed, combining the principles of theory and a data-driven content analysis. First, 69 episo…
Monte Carlo simulation of energy absorbed in phenolic ESR dosimeters added with gadolinium exposed to thermal, epithermal and fast neutrons
2017
Abstract In this work analyses of the energy released per unit mass in phenolic compound exposed to neutron beams were performed with the aim of predicting the increase in dose achievable by addition of gadolinium (Gd) inside the pellets. In particular, Monte Carlo (MC) simulations were carried out for IRGANOX® 1076 phenolic compound irradiated with neutron beams with different energy spectra at various depths inside a water phantom. The addition of gadolinium increases sensitivity of phenolic ESR (electron spin resonance) dosimeters to neutrons thanks to the high gadolinium cross section for neutron capture and to the large number of secondary particles (mainly Auger and internal conversio…
Electron paramagnetic resonance line shape investigation of the Si-29 hyperfine doublet of the E'γ center in a-SiO2
2007
We report an experimental study by electron paramagnetic resonance (EPR) spectroscopy of the E′γ center and of its hyperfine structure, consisting in a pair of lines split by 42 mT. Our results show that two types of E′γ centers can be distinguished on the basis of the EPR line shapes of their main resonance line and hyperfine structure. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
EPR on Radiation-Induced Defects in SiO2
2014
Continuous-wave electron paramagnetic resonance (EPR) spectroscopy has been the technique of choice for the studies of radiation-induced defects in silica (SiO2) for 60 years, and has recently been expanded to include more sophisticated techniques such as high-frequency EPR, pulse electron nuclear double resonance (ENDOR), and pulse electron spin echo envelope modulation (ESEEM) spectroscopy. Structural models of radiation-induced defects obtained from single-crystal EPR analyses of crystalline SiO2 (alfa-quartz) are often applicable to their respective analogues in amorphous silica (a-SiO2), although significant differences are common.