Polarization-modulation near-field optical microscope for quantitative local dichroism mapping

A couple of experimental techniques have been implemented to an aperture near-field scanning optical microscopy (NSOM) to obtain reliable measurement of sample dichroism on the local scale. First, a method to test NSOM tapered fiber probes toward polarization conservation into the near optical field is reported. The probes are characterized in terms of the in-plane polarization of the near field emerging from their aperture, by using a thin dichroic layer of chromophore molecules, structured along stretched polymeric chains, to probe such polarization when approached in the near-field region of the probe. Second, to assure that the light intensity coupled in the fiber is polarization independent, an active system operating in real time has been realized. Such combination of techniques allowed quantitative imaging of local dichroism degree and average orientation by means of dual-phase lock-in demodulation of the optical signal. Translation of the coupled light polarization state in the near field has been observed for one-half of the tested probes. For the others, the tip acts as a polarizer, and therefore showed it was not suitable for polarization modulation NSOM measurements

Fermi surfaces of single layer dielectrics on transition metals

Single sheets of hexagonal boron nitride on transition metals provide a model system for single layer dielectrics. The progress in the understanding of h-BN layers on transition metals of the last 10 years are shortly reviewed. Particular emphasis lies on the boron nitride nanomesh on Rh(111), which is a corrugated single sheet of h-BN, where the corrugation imposes strong lateral electric fields. Fermi surface maps of h-BN/Rh(111) and Rh(111) are compared. A h-BN layer on Rh(111) introduces no new bands at the Fermi energy, which is expected for an insulator. The lateral electric fields of h-BN nanomesh violate the conservation law for parallel momentum in photoemission and smear out the momentum distribution curves on the Fermi surface.Comment: 14 pages, 6 figures, 1 table, 1 equation, Accepted for publication in the Special Surface Science issue in honor of Gerhard Ertl's Nobel Priz

Biomonitoring of coastal areas: cadmium effect on cytoskeleton of the calcisponge <i>Clathrina clathrus</i> = Monitoraggio costiero: effetto del cadmio sul citoscheletro della calcispongia <i>Clathrina clathrus</i>

We detected the effect of Cadmium on the cytoskeleton of Clathrina clathrus by immunocytochemistry, confocal microscopy and immunoblotting. Results highlighted the potential of the sponge to resist to the action of heavy metals through the reorganisation of the tubulins and suggest the utilization of sponges for biomonitoring of environmental pollution

A cento anni dalla Grande Guerra. Vol. 3

The volumes on the Great War that are here published are the result of a series of seminars held at the Department of Political and Social Sciences of the University of Florence between 2014 and 2015. Starting from the occasion of the centennial, the authors wanted to take stock of some specific aspects of the studies related to the First World War. To this purpose, historians, military analysts, political scientists and sociologists have questioned the meaning of the fracture that marks the beginning of the twentieth century and, consequently, the basic aspects of the new policy of the “short century”, from both an Italian and European perspective

Structures, Biological Activities and Phylogenetic Relationships of Terpenoids from Marine Ciliates of the Genus Euplotes

In the last two decades, large scale axenic cell cultures of the marine species comprising the family Euplotidae have resulted in the isolation of several new classes of terpenoids with unprecedented carbon skeletons including the (i) euplotins, highly strained acetylated sesquiterpene hemiacetals; (ii) raikovenals, built on the bicyclo[3.2.0]heptane ring system; (iii) rarisetenolides and focardins containing an octahydroazulene moiety; and (iv) vannusals, with a unique C30 backbone. Their complex structures have been elucidated through a combination of nuclear magnetic resonance spectroscopy, mass spectrometry, molecular mechanics and quantum chemical calculations. Despite the limited number of biosynthetic experiments having been performed, the large diversity of ciliate terpenoids has facilitated the proposal of biosynthetic pathways whereby they are produced from classical linear precursors. Herein, the similarities and differences emerging from the comparison of the classical chemotaxonomy approach based on secondary metabolites, with species phylogenesis based on genetic descriptors (SSU-rDNA), will be discussed. Results on the interesting ecological and biological properties of ciliate terpenoids are also reported

Differential Regulation of GABABReceptor Trafficking by Different Modes ofN-methyl-d-aspartate (NMDA) Receptor Signaling

Inhibitory GABAB receptors (GABABRs) can down-regulate most excitatory synapses in the CNS by reducing postsynaptic excitability. Functional GABABRs are heterodimers of GABAB1 and GABAB2 subunits and here we show that the trafficking and surface expression of GABABRs is differentially regulated by synaptic or pathophysiological activation of NMDA receptors (NMDARs). Activation of synaptic NMDARs using a chemLTP protocol increases GABABR recycling and surface expression. In contrast, excitotoxic global activation of synaptic and extrasynaptic NMDARs by bath application of NMDA causes the loss of surface GABABRs. Intriguingly, exposing neurons to extreme metabolic stress using oxygen/glucose deprivation (OGD) increases GABAB1 but decreases GABAB2 surface expression. The increase in surface GABAB1 involves enhanced recycling and is blocked by the NMDAR antagonist AP5. The decrease in surface GABAB2 is also blocked by AP5 and by inhibiting degradation pathways. These results indicate that NMDAR activity is critical in GABABR trafficking and function and that the individual subunits can be separately controlled to regulate neuronal responsiveness and survival

Guida alla redazione degli atti amministrativi

La "Guida alla redazione degli atti amministrativi" intende fornire indicazioni per la redazione degli atti per tutti i funzionari della pubblica amministrazione. Si articola in tre parti: (a) la lingua degli atti, (b) la struttura del provvedimento amministrativo, (c) il rinvio ad altri atti. Ne è autore un gruppo di linguisti e giuristi facenti capo all'ITTIG-CNR (Istituto per le Tecniche e Tecnologie dell'Informazione Giuridica) e dell'Accademia della Crusca

Adsorption and self-organization of CuOEP on heterogeneous surfaces : tuning the molecule-substrate interaction

The adsorption and self-organization of copper(II) octaethyl porphyrin (CuOEP) have been studied in detail on heterogeneous surfaces by Scanning Tunnelling Microscopy (STM), Low Energy Electron Diffraction (LEED) and Ultraviolet Photoelectron Spectroscopy (UPS). The research has been focussed both on the adsorption of CuOEP on clean metals as well as on ultrathin sodium chloride films grown on metals. For this reason, in a first stage, the growth of NaCl films on Cu(111), Ag(111) and Ag(001) has been carefully investigated. For submonolayer coverages the samples show the formation of NaCl islands with a characteristic rectangular shape, which coexist with clean metal regions. Salt structurestoML thick can be identified. CuOEP molecules have been deposited on the so prepared heterogeneous salt-metal surfaces. STM reveals that the molecules self organize in ordered monolayers on the bare metal areas as well as on the NaCl islands. Series of observations performed by increasing the CuOEP coverage in steps fromtoML revealed that the assembly develops in a hierarchical fashion. Molecules sequentially adsorb and assemble first on the bare metal, then on the 1-layer and 2-layer thick NaCl areas. From these observations it can be inferred that the adsorption energy of CuOEP decreases by introducing an insulator layer and by increasing its thickness. Moreover, the investigation of the STM appearance of CuOEP as a function of the bias voltage, indicates a weaker adsorbate-substrate interaction on the NaCl/metal system than on the bare metal. The adsorption of CuOEP on the clean metal has been further investigated by LEED and UPS. Combining LEED and STM, the structure of the molecular layer formed on Cu(111), Ag(111) and Ag(001) is determined. Information on the adsorption conformation of CuOEP has also been gained by high resolution STM. In these measurements several intramolecular features can be recognized and they fit very well with simulated STM images based on DFT calculations. The theoretical predictions of the molecular orbital energies fit also very well with the UPS measurements. In particular the position and the relative intensity of HOMO and HOMO-1 levels show a very good agreement between experiment and calculation. UPS has also been used to measure the work function change of the various metal substrates upon CuOEP adsorption. These experiments prove that, for all metal investigated, a charge transfer from the molecule to the substrate takes place. This charge transfer is found to depend on the work function of the substrate. In particular the comparison between the Ag(111) and Ag(001) cases demonstrates that the observed work function change does not depend only on the chemistry of the substrate but also on the details of the surface electronic structure