Mediterranean Institute of Fundamental Physics

Optimizing the electrochemical performance of sodium manganites as high-energy cathode materials for sodium-ion batteries requires a deep understanding of their electronic properties, intercalation voltages and sodium migration mechanisms. In this work, we present a comprehensive study of pristine (NaxMnO2), doped (NaxLi0.17Mg0.17Mn0.66O2) and mixed transition-metal (NaxNi0.33Mn0.67O2, NaxTi0.17Ni0.33Mn0.5O2, and NaxFe0.17Ni0.33Mn0.5O2) P2-type layered sodium manganese oxides (x = 0 and x = 1), based on density functional theory with on-site U Hubbard interactions to accurately model the properties arising from the strongly correlated nature of transition-metal 3d states in these lamellar systems. The on-site U Hubbard parameters are computed fully from first-principles using linear response theory. For these mixed-valence cathodic materials, we report calculated oxidation states and intercalation voltages in very good agreement with experimental measurements. Moreover, sodium migration pathways are studied, elucidating the activation energies, the migration mechanisms and their tuning with substitution. In particular, Ni and Ti substitution emerges as the most promising strategy for realizing a fully post-lithium and high-performance cathode. Our findings advance the rational design of next-generation energy storage materials by combining advanced computational techniques with experimental validation, offering insights into optimizing the electrochemical and ionic transport properties of sodium-based positive electrodes.

ABSTRACTThe blue shark (Prionace glauca) is a widely distributed pelagic predator that undergoes ontogenetic morphological changes that reflect ecological and functional adaptations. Investigating this aspect could provide powerful tools for elucidating the patterns of trait variation and their significance in relation to environmental conditions. This study explores morphometric variation and its ecomorphological implications in the Mediterranean blue shark population using linear and geometric morphometric analyses. A total of 119 specimens (64 females, 55 males), spanning from juvenile (total lengths [TLs] 85.4–149.8 cm in females and 82.9–121.2 cm in males) to adult (TLs 150.4–333.1 cm in females and 133.2–206.8 cm in males) stages, were analysed through a set of 30 linear measurements. Linear morphometric analysis identified significant differences between the juvenile and subadult/adult groups, particularly in the anterior body region and pectoral fin measurements. Geometric morphometric results revealed that juveniles have a more heterocercal caudal fin shape, which transitions to a less heterocercal form in adults, with a proportionally larger ventral lobe. The first dorsal fin showed positive allometry, becoming higher. The observed ontogenetic differences could improve energy efficiency and manoeuvrability. This aligns with the diel vertical migrations (DVM) of larger individuals and their need for sustained swimming during long‐distance migrations, as well as the enhanced manoeuvrability required by juveniles, notably for predator avoidance. These morphological changes likely reflect adaptations to changing energy requirements and locomotion needs throughout life stages. Although blue sharks maintain a generalist diet across ontogeny, these adaptations may optimise feeding efficiency and swimming performance, particularly in adults. This study highlights the interplay between ontogeny, morphology and ecological function, shedding light on the selective pressures that shape the life history strategies of blue sharks. The findings emphasise the importance of integrating ontogenetic perspectives into ecomorphological studies to better understand the evolutionary adaptations of pelagic sharks.

The Sun albedo of Cosmic Rays (CRs) at GeVs energy has been discovered recently by the FERMI satellite. They are traces of atmospheric CRs hitting solar atmosphere and reflecting skimming gamma photons. Even if relevant for astrophysics, as being a trace of atmospheric solar CR noises they cannot offer any signal of neutrino astronomy. On the contrary, the Moon with no atmosphere, may become soon a novel filtering calorimeter and an amplifier of energetic muon astronomical neutrinos (at TeV up to hundred TeVs energy); these lepton tracks leave an imprint in their beta decay while in flight to Earth. Their TeV electron air-shower are among the main signals. Also, a more energetic, but more rare, PeV up to EeV tau lunar neutrino events may be escaping as a tau lepton from the Moon: [Formula: see text] PeV secondaries, then, may be shining on Earth’s atmosphere in lunar shadows in a surprising way. One or a few gamma air-shower events inside the Moon shadows may occur each year in near future Cherenkov telescope array (CTA) or large high altitude air shower observatory (LHAASO) TeV gamma array detector, assuming a nonnegligible astrophysical TeV up to hundred TeV neutrino component (with respect to our terrestrial ruling atmospheric ones); these signals will open a new wonderful passe-partout keyhole for neutrino, been seen along the Moon. The lunar solid angle is small and the muon or tau expected rate is rare, but with the future largest tau radio array as the giant radio array for neutrino detection (GRAND), one might well discover such neutrino imprint.

Afro-Palearctic migrants move between breeding and wintering grounds along flyways determined by several factors (bird morphology, geography, behavioural adaptations) and raptors often concentrate at straits to avoid long sea crossings. Here we test the hypothesis that raptor passages across different areas of the Turkish straits are similar in species composition as well as flight behaviour. We made simultaneous observations at the Bosphorus and at the Dardanelles in autumn 2010. We tested the influence of weather, time of day and flock size on the intensity and spatial shift of migratory flow as well as the tendency to cross the Dardanelles Strait rather than follow the peninsula. We also collected information of the flight altitude of raptors using an optical range finder. The species composition observed at the two sites was completely different, with eagles predominating at the Bosphorus and small and medium-sized raptors predominating at the Dardanelles Strait. Compensation for wind drift at the Bosphorus was species-specific, with small and medium-sized raptors showing a drift effect by crosswinds, and eagles showing compensation and overcompensation. Mean flight altitude was similar among species, while the response to weather conditions varied, being mainly affected by wind. In the case of Short-toed Snake-eagles, flight ability and response to weather conditions was also age-dependent. These results show that the flight strategies of migrating raptors are species-specific even if some flight parameters may converge as a result of risk minimisation. The differences between species and flyways probably reflect interspecific differences in the ability to fly over water.

Исследован поляритонный спектр неидеальной одномерной решетки связанных микрорезонаторов, содержащих квантовые точки. С помощью численного моделирования в рамках приближения виртуального кристалла изучены особенности дисперсии электромагнитных возбуждений такой системы, вызванные как вариацией расстояний между ближайшими резонаторами, так и вариацией квантовых точек по составу. Получена плотность состояний исследуемых квазичастиц. Работа выполнена в рамках Европейской программы FP7-PEOPLE-2013-IRSES (грант N 612600 "LIMACONA"). DOI: 10.21883/FTT.2017.04.44277.340

Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed.Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007.In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources.

We study localized photonic excitations in a quasi-two-dimensional non-ideal binary microcavity lattice with use of the virtual crystal approximation. The effect of point defects (vacancies) on the excitation spectrum is investigated by numerical modelling. We obtain the dispersion and the energy gap of the electromagnetic excitations which may be considered as Frenkel exciton-like quasiparticles and analyze the dependence of their density of states on the defect concentrations in a microcavity supercrystal.