167 research outputs found

    In-Plane Hydrogen Bonds and Out-of-Plane Dipolar Interactions in Self-Assembled Melem Networks

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    Melem(2,6,10-triamino-s-heptazine) is the building block of melon,a carbon nitride (CN) polymer that is proven to produce H2 from water under visible illumination. With the aim of bringing additional insight into the electronic structure of CN materials, we performed a spectroscopic characterization of gas-phase melem and of a melem-based self-assembled 2D H-bonded layer on Au(111) by means of ultraviolet and X-ray photoemission spectroscopy (UPS, XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. In parallel, we performed density functional theory (DFT) simulations of the same systems to unravel the molecular charge density redistribution caused by the in-plane H-bonds. Comparing the experimental results with the spectroscopic DFT simulations, we can correlate the induced charge accumulation on the N-amino atoms to the red-shift of the corresponding N 1s binding energy (BE) and of the N-amino 1s -> LUMO+n transitions. Moreover, when introducing a supporting Au(111) surface in the computational simulations, we observe a molecule-substrate interaction that almost exclusively involves the out-of-plane molecular orbitals, leaving those engaged in the in-plane H-bonded network rather unperturbed

    The European project HIALINE (Health Impacts of Airborne Allergen Information Network): results of pollen and allergen of Betula monitoring in Parma (2009)

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    Introduction. Exposure to allergens is pivotal in determining sensitization and allergic symptoms in individuals. Pollen grain counts in ambient air have traditionally been assessed to estimate airborne allergen exposure. However, the exact allergen content in ambient air is unknown. HIALINE therefore monitored atmospheric concentrations of Betula, Poaceae and Olea pollen grains and matched their major allergens Bet v1, Phl p5 and Ole e1 across Europe. Monitoring the allergens themselves together with pollen in ambient air might be an improvement in allergen exposure assessment. New knowledge through the use of new experimental approaches in the field of aerobiological monitoring will enable better in the prevention and clinical management of pollinosis. In order to disseminate the knowledge of the project we present the results of first year of birch pollen grains and the matched major pollen allergen Bet v1 monitored in Parma (UNIPR), Italy with a short reference to the results obtained by the other participants and about developing models of dissemination and forecasts of pollen and allergens. Materials and methods. The pollen was sampled by a Hirst pollen trap. Allergens was collected with a CHEMVOL® high-volume cascade impactor, extracted from pollen and quantified by ELISA. Antibodies for analysis of Bet v1 are delivered by the industrial partner in this project. Quality control has been carried out for the monitoring pollen activities and allergen concentrations. Results. The project has highlighted that it is possible also to measure pollen allergen in ambient air in different European areas. The results obtained from the center of Parma and other European partners have highlighted the different allergenic powers of pollen of Betula, in different geographical areas. Moreover, daily in each area the allergenic power of pollen grains was very variable. Discussion. HIALINE has been a very important project to understand the mechanisms of sensitization, clinical management of pollinosis and to improve immunotherapy towards a tailored immunotherapy. The results of the project will help medical doctors, authorities and patients, to better manage the different aspects related to pollinosis

    Observation of the Shadowing of Cosmic Rays by the Moon using a Deep Underground Detector

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    Using data collected by the MACRO experiment during the years 1989-1996, we show evidence for the shadow of the moon in the underground cosmic ray flux with a significance of 3.6 sigma. This detection of the shadowing effect is the first by an underground detector. A maximum-likelihood analysis is used to determine that the angular resolution of the apparatus is 0.9+/-0.3 degrees. These results demonstrate MACRO's capabilities as a muon telescope by confirming its absolute pointing ability and quantifying its angular resolution.Comment: 14 pages, 8 figures Submitted to Phys. Rev.

    Measurement of the atmospheric neutrino-induced upgoing muon flux using MACRO

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    We present a measurement of the flux of neutrino-induced upgoing muons (~100 GeV) using the MACRO detector. The ratio of the number of observed to expected events integrated over all zenith angles is 0.74 +/- 0.036 (stat) +/- 0.046(systematic) +/- 0.13 (theoretical). The observed zenith distribution for -1.0 < cos(theta) < -0.1 does not fit well with the no oscillation expectation, giving a maximum probability for chi^2 of 0.1%. The acceptance of the detector has been extensively studied using downgoing muons, independent analyses and Monte-Carlo simulations. The other systematic uncertainties cannot be the source of the discrepancies between the data and expectations. We have investigated whether the observed number of events and the shape of the zenith distribution can be explained by a neutrino oscillation hypothesis. Fitting either the flux or zenith distribution independently yields mixing parameters of sin^2 (2theta)=1.0 and delta m^2 of a few times 10^-3 eV^2. However, the observed zenith distribution does not fit well with any expectations giving a maximum probability for chi^2 of 5% for the best oscillation hypothesis, and the combined probability for the shape and number of events is 17%. We conclude that these data favor a neutrino oscillation hypothesis, but with unexplained structure in the zenith distribution not easily explained by either the statistics or systematics of the experiment.Comment: 7 pages (two-column) with 4 figure

    Limits on dark matter WIMPs using upward-going muons in the MACRO detector

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    We perform an indirect search for Weakly Interacting Massive Particles (WIMPs) using the MACRO detector to look for neutrino-induced upward-going muons resulting from the annihilation of WIMPs trapped in the Sun and Earth. The search is conducted in various angular cones centered on the Sun and Earth to accommodate a range of WIMP masses. No significant excess over the background from atmospheric neutrinos is seen and limits are placed on the upward-going muon fluxes from Sun and Earth. These limits are used to constrain neutralino particle parameters from supersymmetric theory, including those suggested by recent results from DAMA/NaI.Comment: 14 pages, 7 figures, submitted to Phys. Rev.

    Atmospheric neutrino induced muons in the MACRO detector

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    A measurement of the flux of neutrino-induced muons using the MACRO detector is presented. Different event topologies, corresponding to different neutrino parent energies can be detected. The upward throughgoing muon sample is the larger event sample. The observed upward-throughgoing muons are 26% fewer than expected and the zenith angle distribution does not fit with the expected one. Assuming neutrino oscillations, both measurements suggest maximum mixing and Dm2 of a few times 10-3 eV2. The other samples are due to the internally produced events and to upward-going stopping muons. These data show a regular deficit of observed events in each angular bin, as expected assuming neutrino oscillations with maximum mixing, in agreement with the analysis of the upward-throughgoing muon sample.Comment: 7 pages 6 figures to appear in the proceedings of XVIII International Conference on Neutrino Physics and Astrophysics (Neutrino'98), Takayama, Japan 4-9 June, 199

    Nuclearite search with the MACRO detector at Gran Sasso

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    In this paper we present the results of a search for nuclearites in the penetrating cosmic radiation using the scintillator and track-etch subdetectors of the MACRO apparatus. The analyses cover the beta =v/c range at the detector depth (3700 hg/cm^2) 10^-5 < beta < 1; for beta = 2 x 10^-3 the flux limit is 2.7 x 10^-16 cm^-2 s^-1 sr^-1 for an isotropic flux of nuclearites, and twice this value for a flux of downgoing nuclearites.Comment: 16 pages, 4 Encapsulated Postscript figures, uses article.sty. Submitted to The European Physical Journal

    Activating Killer Immunoglobulin Receptors and HLA-C: A successful combination providing HIV-1 control

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    Several studies demonstrated a relevant role of polymorphisms located within the HLA-B and -C loci and the Killer Immunoglobulin Receptors (KIRs) 3DL1 and 3DS1 in controlling HIV-1 replication. KIRs are regulatory receptors expressed at the surface of NK and CD8+ T-cells that specifically bind HLA-A and -B alleles belonging to the Bw4 supratype and all the -C alleles expressing the C1 or C2 supratype. We here disclose a novel signature associated with the Elite Controller but not with the long-term nonprogressor status concerning 2DS activating KIRs and HLA-C2 alleles insensitive to miRNA148a regulation. Overall, our findings support a crucial role of NK cells in the control of HIV-1 viremia

    Spatial and Temporal Variations in the Annual Pollen Index Recorded by Sites Belonging to the Portuguese Aerobiology Network

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    This study presents the findings of a 10-year survey carried out by the Portuguese Aerobiology Network (RPA) at seven pollen-monitoring stations: five mainland stations (Oporto, Coimbra, Lisbon, Évora and Portimão) and two insular stations [Funchal (Madeira archipelago) and Ponta Delgada (Azores archipelago)]. The main aim of the study was to examine spatial and temporal variations in the Annual Pollen Index (API) with particular focus on the most frequently recorded pollen types. Pollen monitoring (2003–2012) was carried out using Hirst-type volumetric spore traps, following the minimum recommendations proposed by the European Aerobiology Society Working Group on Quality Control. Daily pollen data were examined for similarities using the Kruskal–Wallis nonparametric test and multivariate regression trees. Simple linear regression analysis was used to describe trends in API. The airborne pollen spectrum at RPA stations is dominated by important allergenic pollen types such as Poaceae, Olea and Urticaceae. Statistically significant differences were witnessed in the API recorded at the seven stations. Mean API is higher in the southern mainland cities, e.g. Évora, Lisbon and Portimão, and lower in insular and littoral cities. There were also a number of significant trends in API during the 10-year study. This report identifies spatial and temporal variations in the amount of airborne pollen recorded annually in the Portuguese territory. There were also a number of significant changes in API, but no general increases in the amount of airborne pollen
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