374 research outputs found
A mini-phoswich scintillator as a possible stop detector for the NUMEN project
No full textAbstractIn the framework of the NUMEN project, aimed at the investigation of the nuclear matrix elements connected to the neutrinoless double beta decay by means of the Double Charge Exchange nuclear reactions (Cappuzzello et al., 2015), a high granularity stop detector for heavy ions is needed. It has to allow the identification of ions up to Z≈10 while maintaining a total energy resolution around 2%. As the use of silicon detectors is not possible, due to their poor radiation hardness, scintillators are being investigated as possible candidates. In this paper we show a promising result obtained using a plastic+inorganic phoswich scintillator readout by means of a Silicon Photo Multiplier
The B16 Standard Solar Models
No full textWe describe a new generation of standard solar models (SSMs), Barcelona 2016 or B16 for short, that includes recent updates on some important nuclear reaction rates, a more consistent treatment of the equation of state and a novel and flexible treatment of opacity uncertainties. Two large sets of SSMs, each based on a different canonical set of solar abundances with high and low metallicity, are calculated and compared with different ensembles of solar observables including solar neutrinos, surface helium abundance, depth of convective envelope and sound speed profile
A constrained analysis of the40 ca(18 o,18 f)40 k direct charge exchange reaction mechanism at 275 mev
No full textThe40 Ca(18 O,18 F)40 K single charge exchange (SCE) reaction is explored at an incident energy of 275 MeV and analyzed consistently by collecting the elastic scattering and inelastic scattering data under the same experimental conditions. Full quantum-mechanical SCE calculations of the direct mechanism are performed by including microscopic nuclear structure inputs and adopting either a bare optical potential or a coupled channel equivalent polarization potential (CCEP) constrained by the elastic and inelastic data. The direct SCE mechanism describes the magnitude and shape of the angular distributions rather well, thus suggesting the suppression of sequential multi-nucleon transfer processes. © 2021 Cavallaro, Bellone, Calabrese, Agodi, Burrello, Cappuzzello, Carbone, Colonna, Deshmukh, Lenske, Spatafora, Acosta, Amador-Valenzuela, Borello-Lewin, Brischetto, Calvo, Capirossi, Chávez, Ciraldo, Cutuli, Delaunay, Djapo, Eke, Finocchiaro, Firat, Fisichella, Foti, Guazzelli, Hacisalihoglu, Iazzi, Fauci, Linares, Lubian, Medina, Moralles, Oliveira, Pakou, Pandola, Petrascu, Pinna, Russo, Sgouros, Solakci, Soukeras, Souliotis, Torresi, Tudisco, Yildirin and Zagatto
Efficacy of mesenchymal stem cells depends on administration route in a murine model of acid inhalation ARD8
No full textINTRODUCTION. Acute respiratory distress syndrome (ARDS) is still associated with high mortality, as only few effective therapies are available. Mesenchymal stem cells (MSCs) showed beneficial effects in various experimental ARDS model, by fine balancing inflammation with increased ability of eliminating the noxa without additional injury. Data on the effects of MSCs in acid inhalation-induced ARDS still lack.
OBJECTIVES. Aim of this study was to test the therapeutic effects of MSCs, administered by intravenous (iv) and intraperitoneal (ip) route, in a murine model of ARDS induced by acid inhalation.
METHODS. Intubated and ventilated mice received 1.5 mL/kg HCl (0.1M) into the right bronchus and were immediately extubated. One hour after acid instillation, MSCs were injected ip or iv (106 cells in 200 μl solution for both routes). Mice treated by iv or ip PBS (200μl) served as controls. Twenty-four hours after MSCs administration mice were sacrificed and arterial blood gases (FiO2 = 0.21) and bronchoalveolar lavage (BAL) were analyzed to assess lung injury.
RESULTS. Survival at 24 hours was 95% for MSCs ip and 85% for iv; no mice died in the PBS groups. Mice treated with MSCs ip showed significantly (p=0.013) higher partial pressure of oxygen in arterial blood (Figure 1) associated with reduction in number of neutrophils recovered in BAL (p=0.055), compared to PBS ip group (Figure 2). In contrast, mice that received MSCs intravenously did not show any beneficial effects in terms of oxygenation and neutrophils recruitment in the alveolar space, if compared to PBS iv group. CONCLUSIONS. MSCs injected intraperitoneally 1 h after onset of acid-induced experimental
ARDS determine a significant improvement in oxygenation at 24 h, possibly by
dampening recruitment of activated neutrophils in the alveolar space. On the other hand,
MSCs iv do not seem to attenuate acid-induced ARDS, maybe because acid environment in
lung parenchyma destroy a significant amount of MSCs as they pass through lung vascular
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Two-step transfer mechanisms in the charge-exchange reaction 40Ca(18O, 18F) 40K at 275 MeV
No full textThe nuclear collision O18+Ca40 at 275 MeV is theoretically studied in the elastic, inelastic, one-nucleon transfer, and charge-exchange channels. The elastic scattering channel is treated within the optical model framework with the help of semimicroscopic double folding potentials, which are constructed by using the realistic nuclear matter densities obtained within the Hartree-Fock-Bogoliubov method, while the distorted wave Born approximation method is adopted to calculate differential cross sections for the other channels. The charge exchange nuclear reaction Ca40(O18, F18)K40 is analyzed by assuming the two-step transfer mechanisms, namely by considering a succession of proton-neutron pickup-stripping processes. Large-scale shell-model calculations are employed to compute the spectroscopic amplitudes, needed in our approach. When compared to the available experimental angular distributions, the obtained results show that the two-step transfer mechanisms play a relevant role in the description of the Ca40(O18, F18)K40 reaction and need to be accounted for in any accurate analysis of the measured cross section
Mesenchymal Stromal Cell-Derived PTX3 Promotes Wound Healing via Fibrin Remodeling
No full textAlthough mesenchymal stromal cells (MSCs) can promote wound healing in different clinical settings, the underlying mechanism of MSC-mediated tissue repair has yet to be determined. Because a nonredundant role of pentraxin 3 (PTX3) in tissue repair and remodeling has been recently described, here we sought to determine whether MSC-derived PTX3 might play a role in wound healing. Using a murine model of skin repair, we found that Ptx3-deficient (Ptx3−/−) MSCs delayed wound closure and reduced granulation tissue formation compared with wt MSCs. At day 2, confocal microscopy revealed a dramatic reduction in green fluorescent protein (GFP)-expressing Ptx3−/− MSCs recruited to the wound, where they appeared to be not only poorly organized in bundles but also scattered in the extracellular matrix. These findings were further confirmed by quantitative biochemical analysis of GFP content in wound extracts. Furthermore, Ptx3−/− MSC-treated skins displayed increased levels of fibrin and lower levels of D-dimer, suggesting delayed fibrin-rich matrix remodeling compared with control skins. Consistently, both pericellular fibrinolysis and migration through fibrin were found to be severely affected in Ptx3−/− MSCs. Overall, our findings identify an essential role of MSC-derived PTX3 in wound repair underscoring the beneficial potential of MSC-based therapy in the management of intractable wounds
Microscopic cluster model for the description of (18O,16O) two-neutron transfer reactions
No full textExcitation energy spectra and absolute cross-section angular distributions were measured for the 13C(18O,16O)15C two-neutron transfer reaction at 84 MeV incident energy. Exact finite-range coupled reaction channel calculations are used to analyse the data considering both the direct two-neutron transfer and the two-step sequential mechanism. For the direct calculations, two approaches are discussed: The extreme cluster and the newly introduced microscopic cluster. The latter makes use of spectroscopic amplitudes in the centre-of-mass reference frame, derived from shell-model calculations. The results describe well the experimental cross sections
Microscopic cluster model for the description of new experimental results on the C 13 (O 18, O 16) C 15 two-neutron transfer at 84 MeV incident energy
No full textThe C13(O18,O16)C15 reaction is studied at 84 MeV incident energy. Excitation energy spectra and absolute cross-section angular distributions for the strongest transitions are measured with good energy and angular resolutions. Strong selectivity for two-neutron configurations in the states of the residual nucleus is found. The measured cross-section angular distributions are analyzed by exact finite-range coupled reaction channel calculations. The two-particle wave functions are extracted using the extreme cluster and the independent coordinate scheme with shell-model derived coupling strengths. A new approach also is introduced, the microscopic cluster, in which the spectroscopic amplitudes in the center-of-mass reference frame are derived from shell-model calculations using the Moshinsky transformation brackets. This new model is able to describe well the experimental cross section and to highlight cluster configurations in the involved wave functions
The NUMEN Project: Toward new experiments with high-intensity beams
No full textThe search for neutrinoless double-beta (0νββ) decay is currently a key topic in physics, due to its possible wide implications for nuclear physics, particle physics, and cosmology. The NUMEN project aims to provide experimental information on the nuclear matrix elements (NMEs) that are involved in the expression of 0νββ decay half-life by measuring the cross section of nuclear double-charge exchange (DCE) reactions. NUMEN has already demonstrated the feasibility of measuring these tiny cross sections for some nuclei of interest for the 0νββ using the superconducting cyclotron (CS) and the MAGNEX spectrometer at the Laboratori Nazionali del Sud (LNS.) Catania, Italy. However, since the DCE cross sections are very small and need to be measured with high sensitivity, the systematic exploration of all nuclei of interest requires major upgrade of the facility. R&D for technological tools has been completed. The realization of new radiation-tolerant detectors capable of sustaining high rates while preserving the requested resolution and sensitivity is underway, as well as the upgrade of the CS to deliver beams of higher intensity. Strategies to carry out DCE cross-section measurements with high-intensity beams were developed in order to achieve the challenging sensitivity requested to provide experimental constraints to 0νββ NMEs
Interplay of the elastic and inelastic channels in the 16O+27Al scattering at Elab = 280 MeV
No full text<p>Recent data indicated a nuclear rainbow-like pattern in the elastic scattering of 16O + 27Al at Elab = 100 MeV that arises from couplings of the ground to the low-lying states of the 27Al nucleus. Similar effect was identified in the elastic angular distribution of 16O + 12C at Elab = 281 and 330 MeV. These experiments show a crucial role of microscopic details of nuclear structure in the elastic scattering of heavy ions at energies well above the Coulomb barrier. In this work we investigate the 16O + 27Al system at Elab = 280 MeV for which a coupled channel calculation predicts a pronounced nuclear rainbow-like structure. Obtained experimental data show evidences of an important coupling of the elastic channel to the inelastic. Coupled channel calculations reproduce the experimental angular distributions when a re-normalization factor on the real part of the optical potential is introduced. A proper theoretical approach still requires a high degree of accuracy for the nuclear structure models and new tools to deal with collective excitations.</p>
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