Novel graphene/Sn and graphene/SnO_x hybrid nanostructures: Induced superconductivity and band gaps revealed by scanning probe measurements

P&aacute,link&aacute,s, Andrá,s,Moln&aacute,r, Gyö,rgy,Magda, G&aacute,bor Zsolt,Hwang, Chanyong,Tapasztó,, Levente,Samuely, Peter,Szabó,, Pavol,Osv&aacute,th, Zolt&aacute,n Elsevier 2017 Carbon Vol.124 No.-

<P>The development of functional composite nanomaterials based on graphene and metal nanoparticles (NPs) is currently the subject of intense research interest. In this study we report the preparation of novel type of graphene/Sn and graphene/SnOx (1 <= x <= 2) hybrid nanostructures and their investigation by scanning probe methods. First, we prepare Sn NPs by evaporating 7-8 nm tin on highly oriented pyrolytic graphite substrates. Graphene/Sn nanostructures are obtained by transferring graphene on top of the tin NPs immediately after evaporation. We show by scanning tunnelling microscopy (STM) and spectroscopy (STS) that tin NPs reduce significantly the environmental p-type doping of graphene. Furthermore, we demonstrate by low-temperature STM and STS measurements that superconductivity is induced in graphene, either directly supported by Sn NPs or suspended between them. Additionally, we prepare SnOx NPs by annealing the evaporated tin at 500 degrees C. STS measurements performed on hybrid graphene/SnOx nanostructures reveal the electronic band gap of SnOx NPs. The results can open new avenues for the fabrication of novel hybrid superconducting nanomaterials with designed structures and morphologies. (C) 2017 Elsevier Ltd. All rights reserved.</P>

THE FIRST COMBINED SEARCH FOR NEUTRINO POINT-SOURCES IN THE SOUTHERN HEMISPHERE WITH THE ANTARES AND ICECUBE NEUTRINO TELESCOPES

Adri&aacute,n-Martí,nez, S.,Albert, A.,André,, M.,Anton, G.,Ardid, M.,Aubert, J.-J.,Baret, B.,Barrios-Martí,, J.,Basa, S.,Bertin, V.,Biagi, S.,Bormuth, R.,Bouwhuis, M. C.,Bruijn, R. American Astronomical Society 2016 The Astrophysical journal Vol.823 No.1

<P>We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of both detectors, which differ in size and location, forms a window in the southern sky where the sensitivity to point sources improves by up to a factor of 2 compared with individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the southern sky and from a preselected list of candidate objects. No significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for E-2.5 and E-2 power-law spectra with different energy cut-offs.</P>

High-energy neutrino follow-up search of gravitational wave event GW150914 with ANTARES and IceCube

Adri&aacute,n-Martí,nez, S.,Albert, A.,André,, M.,Anghinolfi, M.,Anton, G.,Ardid, M.,Aubert, J.-J.,Avgitas, T.,Baret, B.,Barrios-Martí,, J.,Basa, S.,Bertin, V.,Biagi, S.,Bormuth, R. American Physical Society 2016 Physical Review D Vol.93 No.12

<P>We present the high-energy-neutrino follow-up observations of the first gravitational wave transient GW150914 observed by the Advanced LIGO detectors on September 14, 2015. We search for coincident neutrino candidates within the data recorded by the IceCube and ANTARES neutrino detectors. A possible joint detection could be used in targeted electromagnetic follow-up observations, given the significantly better angular resolution of neutrino events compared to gravitational waves. We find no neutrino candidates in both temporal and spatial coincidence with the gravitational wave event. Within +/- 500 s of the gravitational wave event, the number of neutrino candidates detected by IceCube and ANTARES were three and zero, respectively. This is consistent with the expected atmospheric background, and none of the neutrino candidates were directionally coincident with GW150914. We use this nondetection to constrain neutrino emission from the gravitational-wave event.</P>

Impact of <i>Mycobacterium ulcerans</i> Biofilm on Transmissibility to Ecological Niches and Buruli Ulcer Pathogenesis

Marsollier, Laurent,Brodin, Priscille,Jackson, Mary,Kordul&aacute,kov&aacute,, Jana,Tafelmeyer, Petra,Carbonnelle, Etienne,Aubry, Jacques,Milon, Geneviè,ve,Legras, Pierre,André,, Jean-Paul Public Library of Science 2007 PLoS pathogens Vol.3 No.5

<▼1><P>The role of biofilms in the pathogenesis of mycobacterial diseases remains largely unknown. <I>Mycobacterium ulcerans,</I> the etiological agent of Buruli ulcer, a disfiguring disease in humans, adopts a biofilm-like structure in vitro and in vivo, displaying an abundant extracellular matrix (ECM) that harbors vesicles. The composition and structure of the ECM differs from that of the classical matrix found in other bacterial biofilms. More than 80 proteins are present within this extracellular compartment and appear to be involved in stress responses, respiration, and intermediary metabolism. In addition to a large amount of carbohydrates and lipids, ECM is the reservoir of the polyketide toxin mycolactone, the sole virulence factor of M. ulcerans identified to date, and purified vesicles extracted from ECM are highly cytotoxic. ECM confers to the mycobacterium increased resistance to antimicrobial agents, and enhances colonization of insect vectors and mammalian hosts. The results of this study support a model whereby biofilm changes confer selective advantages to M. ulcerans in colonizing various ecological niches successfully, with repercussions for Buruli ulcer pathogenesis.</P></▼1><▼2><P><B>Author Summary</B></P><P><B/></P><P>Mycobacterium ulcerans is the etiologic agent of Buruli ulcer, a necrotic skin disease affecting humans living close to wetlands in tropical countries. This mycobacteria resides in water where it could colonize many ecological niches such as aquatic plants, herbivorous animals, and water bugs. The latter were shown to be able to transmit the bacteria to mammalian hosts. Here, we described that the bacilli could be structured with a thick envelope called the extracellular matrix (ECM). This peculiar coat contains in small vesicles a toxin named mycolactone, the main virulence factor of M. ulcerans. The ECM confers to the mycobacterium increased resistance to antimicrobial agents and plays a role in virulence. Indeed, a bacteria with ECM is more potent for colonization of insect vectors and mammalian hosts compared to bacteria. Unraveling the regulation of the production of the ECM together with the export of mycolactone will be an important step in developing new pharmacological approaches for the treatment of Buruli ulcer, which has been greatly handicapped by the lack of effectiveness of the current antibiotics.</P></▼2>

Coordinated underground measurements of gamma-ray emitting radionuclides for plasma physics research

Tzika, Faidra,Hult, Mikael,Fenyvesi, Andrá,s,Bandac, Iulian,Degering, Detlev,Ianni, Aldo,Laubenstein, Matthias,de Vismes-Ott, Anne,Marissens, Gerd,Stroh, Heiko,Lutter, Guillaume,Son, Soohyun,Hon Elsevier 2017 Applied radiation and isotopes Vol.126 No.-

<P><B>Abstract</B></P> <P>Forty-eight samples made of CaF<SUB>2</SUB>, LiF and YVO<SUB>4</SUB> were placed inside the KSTAR Tokamak and irradiated by neutrons and charged particles from eight plasma pulses. The aim was to provide information for plasma diagnostics. Due to the short pulse durations, the activities induced in the samples were low and therefore measurements were performed in five low-background underground laboratories. Details of the underground measurements, together with data on the quality control amongst the radiometric laboratories, are presented.</P> <P><B>Highlights</B></P> <P> <UL> <LI> First activation probe experiment was conducted at KSTAR Tokamak. </LI> <LI> The activated samples were measured with low level gamma-ray spectrometry. </LI> <LI> Five CELLAR underground laboratories participated in the measurement campaign. </LI> <LI> The metrological aspects and the comparability of the measurements are discussed. </LI> <LI> The final aim is to determine the neutrons and charged particles fluxes at KSTAR. </LI> </UL> </P>

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

Albareti, Franco D.,Prieto, Carlos Allende,Almeida, Andres,Anders, Friedrich,Anderson, Scott,Andrews, Brett H.,Aragó,n-Salamanca, Alfonso,Argudo-Fern&aacute,ndez, Maria,Armengaud, Eric,Aubourg, American Astronomical Society 2017 The Astrophysical journal Supplement series Vol.233 No.2

<P>The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). As well as its core program, eBOSS contains two major subprograms: the Time Domain Spectroscopic Survey (TDSS) and the SPectroscopic IDentification of ERosita Sources (SPIDERS). This paper describes the first data release from SDSS-IV, Data Release 13 (DR13). DR13 makes publicly available the first 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA. It includes new observations from eBOSS, completing the Sloan Extended QUasar, Emission-line galaxy, Luminous red galaxy Survey (SEQUELS), which also targeted variability-selected objects and X-ray-selected objects. DR13 includes new reductions of the SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification, and new reductions of the SDSS-III APOGEE-1 data, improving stellar parameters for dwarf stars and cooler stars. DR13 provides more robust and precise photometric calibrations. Value-added target catalogs relevant for eBOSS, TDSS, and SPIDERS and an updated red-clump catalog for APOGEE are also available. This paper describes the location and format of the data and provides references to important technical papers. The SDSS web site, http://www.sdss.org, provides links to the data, tutorials, examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned similar to 6 yr operations of SDSS-IV.</P>

Infall Signatures in a Prestellar Core Embedded in the High-mass 70 <i>μ</i>m Dark IRDC G331.372-00.116

Contreras, Yanett,Sanhueza, Patricio,Jackson, James M.,Guzm&aacute,n, André,s E.,Longmore, Steven,Garay, Guido,Zhang, Qizhou,Nguyê,̃,n-Lu’o’, Quang,Tatematsu, Ken’ichi,Nakamura, Fumita American Astronomical Society 2018 The Astrophysical journal Vol.861 No.1

<P>Using Galactic Plane surveys, we have selected a massive (1200M circle dot), cold (14 K) 3.6-70 mu m dark IRDC, G331.372-00.116. This infrared dark cloud (IRDC) has the potential to form high-mass stars, and given the absence of current star formation signatures, it seems to represent the earliest stages of high-mass star formation. We have mapped the whole IRDC with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.1 and 1.3 mm in dust continuum and line emission. The dust continuum reveals 22 cores distributed across the IRDC. In this work, we analyze the physical properties of the most massive core, ALMA1, which has no molecular outflows detected in the CO (2-1), SiO (5-4), and H2CO (3-2) lines. This core is relatively massive (M = 17.6M circle dot), subvirialized (virial parameter alpha(vir) = M-vir/M = 0.14), and is barely affected by turbulence (transonic Mach number of 1.2). Using the HCO+ (3-2) line, we find the first detection of infall signatures in a relatively massive, prestellar core (ALMA1) with the potential to form a high-mass star. We estimate an infall speed of 1.54 km s(-1) and a high accretion rate of 1.96. x. 10(-3) M circle dot yr(-1). ALMA1 is rapidly collapsing, out of virial equilibrium, which is more consistent with competitive accretion scenarios rather than the turbulent core accretion model. On the other hand, ALMA1 has a mass similar to 6 times larger than the clumps Jeans mass, as it is in an intermediate mass regime (M-J = 2.7 < M less than or similar to 30 M circle dot), contrary to what both the competitive accretion and turbulent core accretion theories predict.</P>

OPTICAL AND INFRARED PHOTOMETRY OF GLOBULAR CLUSTERS IN NGC 1399: EVIDENCE FOR COLOR-METALLICITY NONLINEARITY

Blakeslee, John P.,Cho, Hyejeon,Peng, Eric W.,Ferrarese, Laura,Jord&aacute,n, André,s,Martel, André,R. IOP Publishing 2012 The Astrophysical journal Vol.746 No.1

<P>We combine new Wide Field Camera 3 IR Channel (WFC3/IR) F160W (H-160) imaging data for NGC 1399, the central galaxy in the Fornax cluster, with archival F475W (g(475)), F606W (V-606), F814W (I-814), and F850LP (z.(850)) optical data from the Advanced Camera for Surveys (ACS). The purely optical g(475)-I-814, V-606-I-814, and g(475)-z(850) colors of NGC 1399's rich globular cluster (GC) system exhibit clear bimodality, at least for magnitudes I-814 > 21.5. The optical-IR I-814-H-160 color distribution appears unimodal, and this impression is confirmed by mixture modeling analysis. The V-606-H-160 colors show marginal evidence for bimodality, consistent with bimodality in V-606-I-814 and unimodality in I-814-H-160. If bimodality is imposed for I-814-H-160 with a double Gaussian model, the preferred blue/red split differs from that for optical colors; these 'differing bimodalities' mean that the optical and optical-IR colors cannot both be linearly proportional to metallicity. Consistent with the differing color distributions, the dependence of I-814-H-160 on g(475)-I-814 for the matched GC sample is significantly nonlinear, with an inflection point near the trough in the g(475)-I-814 color distribution; the result is similar for the I-814-H-160 dependence on g(475)-z(850) colors taken from the ACS Fornax Cluster Survey. These g(475)-z(850) colors have been calibrated empirically against metallicity; applying this calibration yields a continuous, skewed, but single-peaked metallicity distribution. Taken together, these results indicate that nonlinear color-metallicity relations play an important role in shaping the observed bimodal distributions of optical colors in extragalactic GC systems.</P>

Final report on international comparison CCQM-K74: Nitrogen dioxide, 10 µmol/mol

Flores, Edgar,Idrees, Faraz,Moussay, Philippe,Viallon, Joë,le,Wielgosz, Robert,Fern&aacute,ndez, Teresa,Ramí,rez, Sergio,Rojo, André,s,Shinji, Uehara,Waldé,n, Jari,Sega, Michela Springer-Verlag 2012 METROLOGIA -BERLIN- Vol.49 No.-

<P>There is a high international priority attached to activities which reduce NO<SUB>x</SUB> in the atmosphere. The current level of permitted emissions is typically between 50 µmol/mol and 100 µmol/mol, but lower values are expected in the future. Currently, ambient air quality monitoring regulations also require the measurement of NO<SUB>x</SUB> mole fractions as low as 0.2 µmol/mol. The production of accurate standards at these levels of mole fractions requires either dilution of a stable higher concentration gas standard or production by a dynamic technique, for example one based on permeation tubes.</P><P>The CCQM-K74 key comparison was designed to evaluate the level of comparability of National Metrology Institutes' measurement capabilities and standards for nitrogen dioxide (NO<SUB>2</SUB>) at a nominal mole fraction of 10 µmol/mol.</P><P>The measurements of this key comparison took place from June 2009 to May 2010.</P><P>Seventeen laboratories took part in this comparison coordinated by the BIPM and VSL. The key comparison reference value was based on BIPM measurement results, and the standard measurement uncertainty of the reference value was 0.042 µmol/mol.</P><P>This key comparison demonstrated that the results of the majority of the participants agreed within limits of ±3% relative to the reference value. The results of only one laboratory lay significantly outside these limits. Likewise this comparison made clear that a full interpretation of the results of the comparison needed to take into account the presence of nitric acid (in the range 100 nmol/mol to 350 nmol/mol) in the cylinders circulated as part of the comparison, as well as the possible presence of nitric acid in the primary standards used by participating laboratories.</P><P>Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.</P><P>The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).</P>

Final report of the pilot study CCQM-P110-B1: A comparison of nitrogen dioxide (NO₂) in nitrogen standards at 10 µmol/mol by Fourier transform infrared spectroscopy (FT-IR)

Flores, Edgar,Idrees, Faraz,Moussay, Philippe,Viallon, Joë,le,Wielgosz, Robert,Fern&aacute,ndez, Teresa,Rojo, André,s,Ramí,rez, Sergio,Aoki, Nobuyuki,Kato, Kenji,Jeongsoon, Lee,Moon, D Springer-Verlag 2012 METROLOGIA -BERLIN- Vol.49 No.-

<P>This pilot study compares the performance of participants in analyzing gas mixtures of nitrogen dioxide in nitrogen by comparison with in-house gravimetric standards using Fourier transformed infrared spectroscopy (FT-IR). In this study the same gas mixtures were used as in the key comparison CCQM-K74, which was designed to evaluate the level of comparability of National Metrology Institutes' measurement capabilities for nitrogen dioxide (NO<SUB>2</SUB>) at a nominal mole fraction of 10 µmol/mol. In the comparison CCQM-K74 most of the participants used chemiluminescence, with a small number using UV absorption or FT-IR spectroscopy, and thus it is of interest to improve understanding of the comparative performance of these techniques because they do not exhibit any cross-sensitivity to nitric acid (HNO<SUB>3</SUB>), which was known to be present in the mixtures used for the comparison.</P><P>The results of this pilot study indicate good consistency and a level of agreement similar to that reported in the comparison CCQM-K74, demonstrating that FT-IR can be operated as a comparison method when calibrated with appropriate gas standards and can achieve similar measurement uncertainties to chemiluminescence and UV absorption techniques.</P><P>An additional pilot study, CCQM-P110-B2, was conducted on the same gas mixtures in parallel with this pilot study. The second study addressed FT-IR spectroscopy when used to measure the gas mixtures with respect to reference spectra. The results of this second study will be reported elsewhere.</P><P>Main text.To reach the main text of this paper, click on Final Report.</P><P>The final report has been peer-reviewed and approved for publication by the CCQM-GAWG.</P>