The goal of the NUMEN collaboration is the measurement of the cross sections of Double Charge Exchange reactions for several couple of ion projectile-target, in order to provide helpful data to study ...the nuclear matrix elements of the neutrino-less double β-decay. The need of big statistics and high precision in the measurements require the use of high intensity beams and very thin targets. This creates some problems to the design of the target frame and to the dissipation of the heat generated by the beam. The present paper reports a possible solution for the cooling system and the production technique of a tin target, together with the results of the preliminary tests of heat dissipation.
Mono- and bimetallic palladium–gold catalysts supported on zirconia and ceria, both sulfated and non-sulfated, are tested for the direct synthesis of hydrogen peroxide under very mild (1 bar and 20 ...°C) and non-explosive conditions. Catalysts are characterized by N
2 physisorption, sulfur content analysis, temperature programmed reduction (TPR), Fourier transmission infrared (FTIR) spectroscopy and high resolution transmission electron microscopy (HRTEM). Catalytic tests are carried out with different gas mixtures and after various pretreatments. Best catalytic results are observed using sulfate doped zirconia samples and H
2/O
2 mixtures containing a large excess of oxygen. Monometallic gold catalysts are completely inactive, while the addition of gold to palladium improves both the productivity and the selectivity of the process. Surface oxidized Pd and Pd–Au catalysts pretreated with hydrogen and oxygen show higher activity and selectivity with respect to non-pretreated samples. A mechanistic explanation is proposed.
The study of heavy-ions induced double charge-exchange (HI-DCE) nuclear reactions is a promising way to access data-driven information on neutrino-less double-beta decay nuclear matrix elements. In ...the following, particular attention is given to the (18O,18Ne) and (20Ne,20O) HI-DCE reactions as tools for β+β+ and β−β− decays, respectively. The experiments are performed in Catania at the Laboratori Nazionali del Sud of the Istituto Nazionale di Fisica Nucleare (INFN-LNS). The MAGNEX magnetic spectrometer is used to momentum analyse the ejectiles of a large network of nuclear reactions. New preliminary experimental data for the 76Se(18O,18F)76As and 76Ge(20Ne,20F)76As single charge exchange (SCE) and for the 76Se(18O,18Ne)76Ge and 76Ge(20Ne,20O)76Se DCE nuclear reactions were also investigated.
The 18O+48Ti reaction was studied at the energy of 275 MeV for the first time under the NUMEN and NURE experimental campaigns with the aim of investigating the complete reaction network potentially ...involved in the 48Ti→48Ca double charge exchange transition. Understanding the degree of competition between successive nucleon transfer and double charge exchange reactions is crucial for the description of the meson exchange mechanism. Into this context, angular distribution measurements for one- and two-nucleon transfer reactions for the system 18O+48Ti were performed at the MAGNEX facility of INFN-LNS in Catania. An overview of the status of the analysis for the two-proton transfer reaction will be given.
Quantitative measurements of CO chemisorption in the range 140–180 K, supported by FTIR data on adsorbed CO, were performed on Au/TiO
2, Au/Fe
2O
3, and Au/CeO
2 catalysts. On the first two samples, ...which had similar particle size distributions, an average Au/CO chemisorption stoichiometry of about 3, referred to step-edge Au atoms, was found. On Au/CeO
2, where very small clusters and quite large particles are present, the CO-chemisorbed volume was much higher than expected, due to the prevailing contribution of very small Au clusters. On the same sample, a change in the IR absorption coefficient was observed and was reasonably explained.
Heavy-ion one-nucleon transfer reactions are promising tools to investigate single-particle configurations in nuclear states, with and without the excitation of the core degrees of freedom. An ...accurate determination of the spectroscopic amplitudes of these configurations is essential for the study of other direct reactions as well as beta-decays. In this context, the 76Se(18O,17O)77Se one-neutron transfer reaction gives a quantitative access to the relevant single particle orbitals and core polarization transitions built on 76Se. This is particularly relevant, since it provides data-driven information to constrain nuclear structure models for the 76Se nucleus.The excitation energy spectrum and the differential cross section angular distributions of this nucleon transfer reaction was measured at 275 MeV incident energy for the first time using the MAGNEX large acceptance magnetic spectrometer. The data are compared with calculations based on distorted wave Born approximation and coupled channel Born approximation adopting spectroscopic amplitudes for the projectile and target overlaps derived by large-scale shell model calculations and interacting boson-fermion model.These reactions are studied in the frame of the NUMEN project. The NUMEN (NUclear Matrix Elements for Neutrinoless double beta decay) project was conceived at the Istituto Nazionale di Fisica Nucleare–Laboratori Nazionali del Sud (INFN-LNS) in Catania, Italy, aiming at accessing information about the nuclear matrix elements (NME) of neutrinoless double beta decay (0νββ) through the study of the heavy-ion induced double charge exchange (DCE) reactions on various 0νββ decay candidate targets. Among these, the 76Se nucleus is under investigation since it is the daughter nucleus of 76Ge in the 0νββ decay process.
Quantitative volumetric measurements of low temperature CO chemisorption on Au/ZrO2 catalysts and Fourier transform infrared measurements of adsorbed CO in well defined and controlled conditions of ...temperature and pressure are here presented as widely accessible and reproducible methods for determining the concentration of gold sites able to chemisorb CO on Au/ZrO2 catalysts. HRTEM analyses were also performed in order to support the validity of the measurements.
Patients with vascular parkinsonism have higher cognitive decline and more basal ganglia lesions. We aimed to evaluate the relationship of cognitive impairment with functional connectivity between ...the basal ganglia and cingulate cortex in vascular parkinsonism.
Thirty patients (8 with vascular parkinsonism and 22 with Parkinson disease) and 23 controls were enrolled. The Mattis Dementia Rating Scale and the Stroop Task were used to assess cognitive decline. MR imaging examinations included T1-MPRAGE, FLAIR, and resting-state fMRI sequences. MPRAGE was segmented to obtain basal ganglia and cingulate cortex volumes. FLAIR was segmented to obtain white matter hyperintensity lesion volume. Resting-state fMRI sequences were used to compare basal ganglia functional connectivity with the cingulate cortex between patients and controls.
Patients with vascular parkinsonism exhibited impaired attention, resistance to interference, and inhibitory control and an increased number of errors on the Stroop Task. They also had higher caudate nucleus and white matter hyperintensity lesion volumes, which were positively correlated (ρ = 0.75, P < .0001). Caudate nucleus functional connectivity with the perigenual anterior cingulate cortex was increased in patients with vascular parkinsonism compared with controls and patients with Parkinson disease, and it was positively correlated with the caudate nucleus volume (ρ = 0.44, P = .016). Caudate nucleus functional connectivity with the posterior cingulate cortex was decreased in patients with vascular parkinsonism compared with controls and negatively correlated with the number of errors on the Stroop test (ρ = -0.51, P = .0003).
In patients with vascular parkinsonism, cognitive decline could be related to changes of caudate nucleus functional connectivity with the cingulate cortex at resting-state, which may be induced by ischemia-related remodelling.
Unifacial leaves are described in different angiosperm groups, especially in monocotyledons, which show anatomical and molecular evidence of an abaxialization process. Among the structural ...characters, the anatomy of epidermis and growth tissues has been reported. Special focus has been given to vascularization patterns, such as the presence and organization of peripheral vascular bundles. In the Aizoaceae, peripheral vascular bundles exhibit two patterns: exoscopic and endoscopic bundles; however, studies including an ontogenetic approach with evidence for a unifacial condition in the group are lacking. We investigated eleven Ruschioideae species, including members of two tribes (Ruschieae and Dorotheantheae), which present flat and terete leaves. Our results show that all leaves present a bifacial leaf base, with xylem cells oriented toward the adaxial face present in collateral vascular bundles. However, the occurrence of peripheral endoscopic vascular bundles in the leaf blade in all terete leaves demonstrates a unifacial condition which is present only at the leaf blades. Based on ontogenetics studies, we demonstrate that the peripheral endoscopic bundles begin their differentiation in the abaxial side of the leaf primordia, suggesting the occurrence of an abaxialization process during leaf blade development.
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