A new naturalized alien plant in Sicily: Cotula australis (Sieber ex Spreng.) Hook. f. (Asteraceae) on the Acropolis of Lipari Island (Aeolian Archipelago)

In February 2018 a copious population of Cotula australis Hook f. (Asteraceae, Anthemideae) was found on the cobblestones of the Acropolis of Lipari Island (Aeolian Archipelago, NE Sicily). This population represents the first record in southern Italy and is located at a distance of about 470 km as the crow flies from the nearest neighbour. From the phytosociological point of view, C. aus- tralis dominates a therophytic subnitrophilous dwarf vegetation of trampled sites which can be ascribed to the cosmopolitan class Polygono-Poetea annuae Rivas Mart. 1975. This plant communi- ty is proposed as a new association, Galio muralis-Cotuletum australis, which can be considered a Mediterranean vicariant of the Polycarpo tetraphylli-Cotuletum australis Wildpret, Perez de Paz, Del Arco & Garcia Gallo 1988, recorded from the Canary Islands and Portugal. Some hypotheses on the origin of the Aeolian population in the frame of a documented very fast recent propagation world- wide are discussed

Potentiometric MRI of a Superconcentrated Lithium Electrolyte: Testing the Irreversible Thermodynamics Approach.

Superconcentrated electrolytes, being highly thermodynamically nonideal, provide a stringent proving ground for continuum transport theories. Herein, we test an ostensibly complete model of LiPF6 in ethyl-methyl carbonate (EMC) based on the Onsager-Stefan-Maxwell theory from irreversible thermodynamics. We perform synchronous magnetic resonance imaging (MRI) and chronopotentiometry to examine how superconcentrated LiPF6:EMC responds to galvanostatic polarization and open-circuit relaxation. We simulate this experiment using an independently parametrized model with six composition-dependent electrolyte properties, quantified up to saturation. Spectroscopy reveals increasing ion association and solvent coordination with salt concentration. The potentiometric MRI data agree closely with the predicted ion distributions and overpotentials, providing a completely independent validation of the theory. Superconcentrated electrolytes exhibit strong cation-anion interactions and extreme solute-volume effects that mimic elevated lithium transference. Our simulations allow surface overpotentials to be extracted from cell-voltage data to track lithium interfaces. Potentiometric MRI is a powerful tool to illuminate electrolytic transport phenomena

Bifurcations of discrete breathers in a diatomic Fermi-Pasta-Ulam chain

Discrete breathers are time-periodic, spatially localized solutions of the equations of motion for a system of classical degrees of freedom interacting on a lattice. Such solutions are investigated for a diatomic Fermi-Pasta-Ulam chain, i. e., a chain of alternate heavy and light masses coupled by anharmonic forces. For hard interaction potentials, discrete breathers in this model are known to exist either as ``optic breathers'' with frequencies above the optic band, or as ``acoustic breathers'' with frequencies in the gap between the acoustic and the optic band. In this paper, bifurcations between different types of discrete breathers are found numerically, with the mass ratio m and the breather frequency omega as bifurcation parameters. We identify a period tripling bifurcation around optic breathers, which leads to new breather solutions with frequencies in the gap, and a second local bifurcation around acoustic breathers. These results provide new breather solutions of the FPU system which interpolate between the classical acoustic and optic modes. The two bifurcation lines originate from a particular ``corner'' in parameter space (omega,m). As parameters lie near this corner, we prove by means of a center manifold reduction that small amplitude solutions can be described by a four-dimensional reversible map. This allows us to derive formally a continuum limit differential equation which characterizes at leading order the numerically observed bifurcations.Comment: 30 pages, 10 figure

Ecologia e distribuzione di Chamaerops humilis L. (Arecaceae) nella Sicilia nord-orientale

I settori costieri e collinari della Sicilia nord-orientale e delle Eolie sono stati esplorati ai fini della raccolta di informazioni aggiornate sulla distribuzione dei popolamenti di palma nana e sulle caratteristiche ecologiche delle stazioni che li ospitano. I risultati delle indagini di campo sono stati integrati dalla verifica dei toponimi locali legati ai nomi dialettali della specie. Si con- ferma la totale assenza della palma nana lungo l’intero settore costiero dei Nebrodi. Dei nove popolamenti accertati, quattro si trovano alle Eolie, due sul versante ionico e tre sul versante tir- renico dei Peloritani; uno di questi ultimi, localizzato su Capo Calavà, risulta inedito. La conco- mitanza di diversi fattori di stress e l’impatto plurisecolare dell’uomo è probabilmente responsa- bile del carattere relittuale di gran parte dei popolamenti considerati, che danno vita a consorzi molto discontinui, e sono rappresentati da piccoli nuclei che formano aggruppamenti semplifi- cati sotto un profilo fisionomico e poveri in termini floristici, perlopiù confinati in contesti roc- ciosi costieri. Di contro, la recente espansione della palma nana registrata a Lipari sembra dipen- dere dalla cessazione delle attività agricole. Infine, i casi di naturalizzazione registrati a Milazzo, Tindari, Panarea, Scaletta Zanclea e Taormina derivano dal suo uso come pianta ornamentale e pongono in risalto l’urgente necessità di regolamentare la sua introduzione per evitare l’inquina- mento genetico dei nuclei autoctoni.The coastal and hilly sectors of NE Sicily and the Aeolian Archipelago have been explored, in order to obtain up-to-date information on the distribution of the populations of Chamaerops humilis and on their site conditions. In addition to the field surveys, any local toponym possibly related to the Sicilian vernacular names of the dwarf palm was checked and verified throughout the investigat- ed area. The total absence of the species along the coasts of Nebrodi Massif is confirmed. Of the 9 extant populations, 4 are located on the Aeolian Islands, 2 along the Ionian coast and 3 along the Tyrrhenian coast of Peloritani Mountains: among them, the one of Capo Calavà represents a new record. The co-occurrence of centuries-long human disturbance and several forms of envi- ronmental stresses could be the reason for the relict connotation of most of the considered popu- lations, which also are very discontinuous and consisting of small patches formed by a few indi- viduals, in simplified and species-poor assemblages, mostly found on sea-facing rocky cliffs. On the other hand, the recent spread of Chamaerops humilis in Lipari could be related to the aban- donment of agricultural practices. Finally, the naturalisation cases recorded in Milazzo, Tindari, Panarea, Scaletta Zanclea and Taormina, where the dwarf palm escaped from public and private gardens, point out the urgent need of regulating its introduction, in order to avoid the genetic pol- lution of the autochthonous populations

Engineering Solution-Processed Non-Crystalline Solid Electrolytes for Li Metal Batteries

Non-crystalline Li-ion solid electrolytes (SEs), such as lithium phosphorus oxynitride, can uniquely enable high-rate solid-state battery operation over thousands of cycles in thin film form. However, they are typically produced by expensive and low throughput vacuum deposition, limiting their wide application and study. Here, we report non-crystalline SEs of composition Li-Al-P-O (LAPO) with ionic conductivities > 10-7 S cm-1 at room temperature made by spin coating from aqueous solutions and subsequent annealing in air. Homogenous, dense, flat layers can be synthesized with submicrometer thickness at temperatures as low as 230 °C. Control of the composition is shown to significantly affect the ionic conductivity, with increased Li and decreased P content being optimal, while higher annealing temperatures result in decreased ionic conductivity. Activation energy analysis reveals a Li-ion hopping barrier of ≈0.4 eV. Additionally, these SEs exhibit low room temperature electronic conductivity (< 10-11 S cm-1) and a moderate Young’s modulus of ≈54 GPa, which may be beneficial in preventing Li dendrite formation. In contact with Li metal, LAPO is found to form a stable but high impedance passivation layer comprised of Al metal, Li-P, and Li-O species. These findings should be of value when engineering non-crystalline SEs for Li-metal batteries with high energy and power densities

Relationship between recruitment and mother plant vitality in the alien species Acacia cyclops A. Cunn. ex G. Don

Acacia cyclops is a widespread invader in Mediterranean-climate regions. However, although its naturalization in the Mediterranean Basin dates back only a few years ago, and the invasion process has not been studied hitherto. We investigated seedlings recruitment strategy adopted by A. cyclops in a small island (Lampedusa, Italy) where its natural regeneration was strictly confined under mother plants canopy. Healthy plants (DCP), plants at incipient senescence (SCP) and dead plants (DP) were distinguished according to vitality and canopy status. Living plants were also characterized in relation to leaf C and N isotope composition. Regeneration pattern (seedlings and saplings abundance) was related to the microclimatic differences (soil temperature, air temperature and humidity, soil nutrients, light) observed between canopies and adjacent open areas, and among canopy types. Living canopies ensure milder conditions, reducing extreme values as well as fluctuations between night and day. However, beneath canopies (DP, SCP and DCP) seedlings may benefit from significantly higher soil nutrients content than in the outside, while light availability was much higher under DP. Saplings to seedlings ratio was found to be around 12 under DP, while under SCP it was slightly higher than 1, and just less than 0.5 under DCP. Moreover, saplings growth was significantly higher under SCP and DP, suggesting a prominent role of light in driving seedlings recruitment. Stable isotope analyses of C and N provided ecophysiological information in relation to changes in canopies structure. Thus, while seedling stage appears to be more nutrient-limited, subsequent sapling stage is much more light-limited. Although the species is not yet displaying an invasive spreading on the island, our study provides clear evidence that senescent canopies are better facilitators than healthy in preserving the invasive potential of A. cyclops. This finding suggests some best practices in order to gradually reduce the presence of the alien species within its pristine nuclei of introduction

Floristic and vegetation changes on a small mediterranean island over the last century

A synthetic and updated overview about the vascular flora and vegetation of the Island of Capo Passero (SE‐Sicily) is provided. These data issue from two series of field surveys—the first carried out between 1997 and 2000, and the second between 2005 and 2019 and mostly focused on refining and implementing vegetation data. The current islet’s flora consists of 269 taxa, of which 149 (58%) are annual plants. The Mediterranean species are largely prevailing, 108 (40%) of which have a strictly Mediterranean biogeographical status. The comparison with a species list published in 1919 and updated in 1957 suggest that, despite the overall prevalence of anemochorous taxa, the vertebrate fauna represents an important vector for the plant colonization of the island, while the immigration of myrmechocorous taxa does not compensate the extinction rate. As many as 202 phy-tosociological relevés, 191 of which issue from original recent field surveys, enabled identifying 12 different plant communities. The comparison with a vegetation map published in 1965 suggests a strong reduction in dune habitats (2120 and 2210 according to EU ‘Habitats’ Directive 92/43), as well as a deep disruption in the succession typical of the local psammophilous vegetation series. In order to preserve rare, endangered and protected plant species (such as Aeluropus lagopoides, Cichorium spinosum, Limonium hyblaeum, L. syracusanum, Poterium spinosum, Senecio pygmaeus and Spergularia heldreichii) and to stop the ongoing habitat degradation, urgent and effective conservation measures should be adopted for this tiny, yet precious islet

Riemann solvers and undercompressive shocks of convex FPU chains

We consider FPU-type atomic chains with general convex potentials. The naive continuum limit in the hyperbolic space-time scaling is the p-system of mass and momentum conservation. We systematically compare Riemann solutions to the p-system with numerical solutions to discrete Riemann problems in FPU chains, and argue that the latter can be described by modified p-system Riemann solvers. We allow the flux to have a turning point, and observe a third type of elementary wave (conservative shocks) in the atomistic simulations. These waves are heteroclinic travelling waves and correspond to non-classical, undercompressive shocks of the p-system. We analyse such shocks for fluxes with one or more turning points. Depending on the convexity properties of the flux we propose FPU-Riemann solvers. Our numerical simulations confirm that Lax-shocks are replaced by so called dispersive shocks. For convex-concave flux we provide numerical evidence that convex FPU chains follow the p-system in generating conservative shocks that are supersonic. For concave-convex flux, however, the conservative shocks of the p-system are subsonic and do not appear in FPU-Riemann solutions