Search results for "FISICA APPLICATA"

Alanine EPR pellets for dosimetry of clinical proton and carbon ion beams

2015

The main gol of the present work is to investigate the response behaviour of alanine EPR pellets in clinical proton anc carbon ion beams. Proton irradiations were carried out at PSI (Switzerland) using both passive and active scattering modality, whereas, C ions irradiation were performed at GSI (Germany) adopting the raster scanning modality.

ALANINE/ESR DOSIMETRY FOR TOTAL BODY IRRADIATION USING AN ANTHROPOMORPHIC PHANTOM

2016

Introduction: Total Body Irradiation (TBI) is a technique widely used in the radiation blood-oncology in the treatment of patients that need bone marrow transplantation or peripheral stem cell transplantation. This technique has some limitations such as the lack of homogeneity of the dose distribution (which may show variations of 20% in the different areas), irradiation of critical organs such as the lungs, the liver, the intestine and the eye-lens which can receive a dose comparable to that nominal and require appropriate shielding and a proper evaluation of the dose absorbed by them. The positive outcome of this type of radiation therapy is strictly related to a precise and accurate meas…

Dosimetry to Electron Spin Resonance (ESR) using organic compounds (alanine and ammonium tartrate) for mixed neutron-gamma fields

2015

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. These dosimeters were exposed to a mixed (neutron-gamma) field mainly composed of thermal neutro…

Comparison of EPR response of alanine and Gd2O3-alanine dosimeters exposed to TRIGA Mainz reactor.

2015

In this work we report some preliminary results regarding the analysis of electron paramagnetic resonance (EPR) response of alanine pellets and alanine pellets added with gadolinium used for dosimetry at the TRIGA research reactor in Mainz, Germany. Two set-ups were evaluated: irradiation inside PMMA phantom and irradiation inside boric acid phantom. We observed that the presence of Gd2O3 inside alanine pellets increases the EPR signal by a factor of 3.45 and 1.24 in case of PMMA and boric acid phantoms, respectively. We can conclude that in the case of neutron beam with a predominant thermal neutron component the addition of gadolinium oxide can significantly improve neutron sensitivity of…

Ni-Based Alloy Nanostructured Electrodes for Alkaline Electrolyzers

In water alkaline electrolyzer field, the development of Nickel-based nanostructured electrode is one of the possible ways to improve the water electrolysis efficiency

The Effect of Electronic Properties of Anodized and Hard Anodized Ti and Ti6Al4V on Their Reactivity in Simulated Body Fluid

2022

The electronic properties of barrier and porous layers on Ti and Ti6Al4V were studied. Barrier anodic oxides grown to 40 V on Ti and on Ti6Al4V are both n-type semiconductors with a band gap of 3.3 eV and 3.4 eV respectively, in agreement with the formation of amorphous TiO2. Anodizing to 200 V at 20 mA cm−2 in calcium acetate and β-glycerol phosphate disodium pentahydrate leads to the formation of Ca and P containing porous films with a photoelectrochemical behaviour dependent on the metallic substrate. A band gap of 3.2 eV and the flat band potential of −0.5 V vs Ag/AgCl were measured for the porous oxide on Ti, while optical transitions at 2.15 eV and a significantly more positive flat b…

MODELLISTICA MATEMATICA E PIATTAFORME INFORMATICHE A SUPPORTO DELLA RICERCA AMBIENTALE

2021

La modellizzazione matematica è diventata ormai uno strumento essenziale nell’avanzamento delle conoscenze in qualsiasi campo della scienza, dall’econometria alla psicologia, dalla chimica all’epidemiologia, come vissuto di recente nella pandemia da SARS-coV-2. Anche quelle che erano una volta discipline “soft” come la biomedicina o l’ecologia possono ora usufruire di tecniche di rappresentazione ed esplicazione dei processi estremamente utili alla comprensione delle dinamiche in gioco. Questa evoluzione, dovuta in non piccola parte all’attuale disponibilità di abbondante potenza di calcolo elettronico a costi ridotti, non è però opera ed appannaggio soltanto della nostra generazione. Lo st…

Characterization of Thin Passive Film-Electrolyte Junctions. The Amorphous Semiconductor (a-SC) Schottky Barrier Approach.

2017

A detailed study of the electronic properties of thin (< 20 nm) anodic TiO2 potentiostatically grown on titanium in two different solutions is presented. The results show that the nature of the anodizing solution affects the electronic properties of the anodic film and in particular the density of electronic state (DOS) distribution. Different DOS were derived from the experimental data analyzed according to the theory of amorphous semiconductor (a-SC) Schottky barrier. It is shown that the usual non-linear and frequency dependent Mott-Schottky plots are in agreement with expected theoretical behaviour of a-SC Schottky barrier. It is shown the importance of the DOS distribution in determini…

Amorphous Silicon Nanotubes via Galvanic Displacement Deposition

2013

Amorphous silicon nanotubes were grown in a single step into a polycarbonate membrane by a galvanic displacement reaction conducted in aqueous solution. In order to optimize the process, a specifically designed galvanic cell was used. SEM images, after polycarbonate dissolution, showed interconnected nanotube bundles with an average length of 18 μm and wall thickness of 38 nm.The deposited silicon was revealed by EDS analysis, whilst X-ray diffraction and Raman spectroscopy showed that nanotubes have an amorphous structure. Silicon nanotubes were also characterized by photo-electrochemical measurements that showed n-type conductivity and optical gap of ~1.6 eV. Keywords: Silicon nanotubes, …

Cholesterol facilitates interactions between α‐synuclein oligomers and charge‐neutral membranes

2015

AbstractOligomeric species formed during α-synuclein fibrillation are suggested to be membrane-disrupting agents, and have been associated with cytotoxicity in Parkinson’s disease. The majority of studies, however, have revealed that the effect of α-synuclein oligomers is only noticeable on systems composed of anionic lipids, while the more physiologically relevant zwitterionic lipids remain intact. We present experimental evidence for significant morphological changes in zwitterionic membranes containing cholesterol, induced by α-synuclein oligomers. Depending on the lipid composition, model membranes are either unperturbed, disrupt, or undergo dramatic morphological changes and segregate …