Electrochemical study of H3PMo12 retention on Vulcan carbon grafted with NH2 and OH groups

In this work, we show a comparative study based on the effects of specific chemical functional groups (–OH, –NH2), grafted on Vulcan carbon (VC) with the incorporation of a specific polyoxometalate (POM), PMo12 (H3PMo12O40), to improve electrochemical performance. We observed a decrease in the specific surface area of the grafted matrices (VC-OH and VC-NH2) [1], and the same trend was observed for PMo12 (POM) incorporation. Our electrochemical studies showed low concentrations of POM in unmodified VCs and higher POM concentrations for grafted matrices (VC-OH and VC-NH2) after 500 voltammetric cycles, especially for the VC grafted with –OH groups (VC-OH-POM). Mechanisms have been proposed for POM interaction with the grafted groups in carbon, emphasizing the role of aqueous medium and redox activity of POM. Cyclic voltammograms suggested the POM anchoring through –OH groups with a strong interaction as a covalent bond, resulting in a surface coverage of 1.66 × 10−11 mol cm−2. Surface modifications could be extrapolated to other carbons, and the materials could be employed for different potential applications such as photocatalysis, amperometric sensors, fuel cells, and supercapacitors.Fil: Cuentas Gallegos, Ana Karina. Universidad Nacional Autónoma de México; México. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: López Cortina, S.. Universidad Autonoma de Nuevo Leon; MéxicoFil: Brousse, T.. Université de Nantes. Institut Des Materiaux Jean Rouxel; FranciaFil: Pacheco Catalán, D.. Centro de Investigación Científica de Yucatán; MéxicoFil: Fuentes Quezada, Eduardo. Centro de Investigación y Desarrollo Tecnológico en Electroquímica; México. Universidad Nacional Autónoma de México; México. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mosqueda, H.. Universidad Autonoma de Nuevo Leon; MéxicoFil: Orozco Gamboa, G.. Centro de Investigación y Desarrollo Tecnológico en Electroquímica; Méxic

CO72 357. Reconstrucción del cuerpo fibroso mitroaórtico: Resultados perioperatorios y supervivencia a largo plazo

ObjetivosDescribir las características clínicas, resultados perioperatorios y supervivencia a largo plazo de pacientes sometidos a sustitución valvular mitral y aórtica con reconstrucción de la fbrosa mitroaórtica según técnica de David.MétodosRevisión retrospectiva de pacientes sometidos a sustitución valvular y reconstrucción de la fibrosa mitroaórtica intervenidos en los últimos 14 años. Se incluyen 27 pacientes, 63% varones, edad 55,3±16,1 años, EuroSCORE 34,4±25,9. El 70,4% de los pacientes presentaban al menos una cirugía previa. La indicación para el procedimiento fue endocarditis infecciosa complicada con absceso de la unión mitroaórtica en el 74,1%; en el restante 25,9% la principal indicación fue la necesidad de ampliación del anillo aórtico en el seno de una valvulopatía mitroaórtica.ResultadosLa supervivencia perioperatoria (30 días) fue del 85,2%. No se observó mortalidad entre los pacientes sin endocarditis. Estancia media: 42,8±42,8 días. Complicaciones perioperatorias: accidente cerebrovascular agudo (ACVA) 3,1% (1), balón de contrapulsación intraaórtica (BCIA) 11,1% (3), insuficiencia renal aguda (IRA) 7,4% (2), infarto agudo de miocardio (IAM) 3,7% (1), reintervención por sangrado 14,8% (4), ventilación mecánica prolongada 11,1% (3), necesidad de marcapasos (MP) definitivo 22,2%. La supervivencia acumulada para los supervivientes a 1, 3 y 5 años fue de 85,9±7,6%, 75,8 ± 9,5% y 45,5 ± 11,1%, respectivamente. No se observó diferencia significativa al comparar la super-vivencia a 1, 3 y 5 años entre los grupos intervenidos por endocarditis y los no endocarditis (log rank 0,146).ConclusionesLa reconstrucción de la fibrosa mitroaórtica mediante técnica de David representa una alternativa terapéutica para el manejo de patología compleja que involucra esta estructura. Hemos observado buenos resultados perioperatorios y a largo plazo teniendo en cuenta el perfil de alto riesgo de los pacientes que requieren este tipo de intervención

Mining minerals and critical raw materials from bittern: Understanding metal ions fate in saltwork ponds

Seawater represents a potential resource for raw materials extraction. Although NaCl is the most representative mineral extracted other valuable compounds such as Mg, Li, Sr, Rb and B and elements at trace level (Cs, Co, In, Sc, Ga and Ge) are also contained in this "liquid mine". Most of them are considered as Critical Raw Materials by the European Union. Solar saltworks, providing concentration factors of up-to 20 to 40, offer a perfect platform for the development of minerals and metal recovery schemes taking benefit of the concentration and purification achieved along the evaporation saltwork ponds. However, the geochemistry of these elements in this environment has not been yet thoroughly evaluated. Their knowledge could enable the deployment of technologies capable to achieve the recovery of valuable minerals. The high ionic strengths expected (0.5-7 mol/kg) and the chemical complexity of the solutions imply that only numerical geochemical codes, as PHREEQC, and the use of Pitzer model to estimate the activity coefficients of the different species in solution can be adopted to provide valuable description of the systems. In the present work, for the first time, PHREEQC Pitzer code database was extended to include the target minor and trace elements using Trapani saltworks (Sicily, Italy) as a case study system. The model was able to predict: i) the purity in halite and the major impurities contained, mainly Ca, Mg and sulphate species; ii) the fate of minor components as B, Sr, Cs, Co, Ge and Ga along the evaporation ponds. The results obtained pose a fundamental step in critical raw materials mining from seawater brine, for process intensification and combination with desalination

Detection of bridge emission above 50 GeV from the Crab pulsar with the MAGIC telescopes

The Crab pulsar is the only astronomical pulsed source detected at very high energy (VHE, E>100GeV) gamma-rays. The emission mechanism of VHE pulsation is not yet fully understood, although several theoretical models have been proposed. In order to test the new models, we measured the light curve and the spectra of the Crab pulsar with high precision by means of deep observations. We analyzed 135 hours of selected MAGIC data taken between 2009 and 2013 in stereoscopic mode. In order to discuss the spectral shape in connection with lower energies, 4.6 years of {\it Fermi}-LAT data were also analyzed. The known two pulses per period were detected with a significance of $8.0 \sigma$ and $12.6 \sigma$. In addition, significant emission was found between the two pulses with $6.2 \sigma$. We discovered the bridge emission above 50 GeV between the two main pulses. This emission can not be explained with the existing theories. These data can be used for testing new theoretical models.Comment: 5 pages, 4 figure

Measurement of the Crab Nebula spectrum over three decades in energy with the MAGIC telescopes

The MAGIC stereoscopic system collected 69 hours of Crab Nebula data between October 2009 and April 2011. Analysis of this data sample using the latest improvements in the MAGIC stereoscopic software provided an unprecedented precision of spectral and night-by-night light curve determination at gamma rays. We derived a differential spectrum with a single instrument from 50 GeV up to almost 30 TeV with 5 bins per energy decade. At low energies, MAGIC results, combined with Fermi-LAT data, show a flat and broad Inverse Compton peak. The overall fit to the data between 1 GeV and 30 TeV is not well described by a log-parabola function. We find that a modified log-parabola function with an exponent of 2.5 instead of 2 provides a good description of the data ($\chi^2=35/26$). Using systematic uncertainties of red the MAGIC and Fermi-LAT measurements we determine the position of the Inverse Compton peak to be at (53 $\pm$ 3stat + 31syst -13syst) GeV, which is the most precise estimation up to date and is dominated by the systematic effects. There is no hint of the integral flux variability on daily scales at energies above 300 GeV when systematic uncertainties are included in the flux measurement. We consider three state- of-the-art theoretical models to describe the overall spectral energy distribution of the Crab Nebula. The constant B-field model cannot satisfactorily reproduce the VHE spectral measurements presented in this work, having particular difficulty reproducing the broadness of the observed IC peak. Most probably this implies that the assumption of the homogeneity of the magnetic field inside the nebula is incorrect. On the other hand, the time-dependent 1D spectral model provides a good fit of the new VHE results when considering a 80 {\mu}G magnetic field. However, it fails to match the data when including the morphology of the nebula at lower wavelengths.Comment: accepted by JHEAp, 9 pages, 6 figure

The unidentified TeV source (TeVJ2032+4130) and surrounding field: Final HEGRA IACT-System results

The unidentified TeV source in Cygnus is now confirmed by follow-up observations from 2002 with the HEGRA stereoscopic system of Cherenkov Telescopes. Using all data (1999 to 2002) we confirm this new source as steady in flux over the four years of data taking, extended with radius 6.2 arcmin (+-1.2 arcmin (stat) +-0.9 arcmin (sys)) and exhibiting a hard spectrum with photon index -1.9. It is located in the direction of the dense OB stellar association, Cygnus OB2. Its integral flux above energies E>1 TeV amounts to \~5% of the Crab assuming a Gaussian profile for the intrinsic source morphology. There is no obvious counterpart at radio, optical nor X-ray energies, leaving TeVJ2032+4130 presently unidentified. Observational parameters of this source are updated here and some astrophysical discussion is provided. Also included are upper limits for a number of other interesting sources in the FoV, including the famous microquasar Cygnus X-3.Comment: 7 pages, 3 figures. Accepted for publication in Astronomy & Astrophysic

First broadband characterization and redshift determination of the VHE blazar MAGIC J2001+439

We aim to characterize the broadband emission from 2FGL J2001.1+4352, which has been associated with the unknown-redshift blazar MG4 J200112+4352. Based on its gamma-ray spectral properties, it was identified as a potential very high energy (VHE; E > 100 GeV) gamma-ray emitter. The source was observed with MAGIC first in 2009 and later in 2010 within a multi-instrument observation campaign. The MAGIC observations yielded 14.8 hours of good quality stereoscopic data. The object was monitored at radio, optical and gamma-ray energies during the years 2010 and 2011. The source, named MAGIC J2001+439, is detected for the first time at VHE with MAGIC at a statistical significance of 6.3 {\sigma} (E > 70 GeV) during a 1.3-hour long observation on 2010 July 16. The multi-instrument observations show variability in all energy bands with the highest amplitude of variability in the X-ray and VHE bands. We also organized deep imaging optical observations with the Nordic Optical Telescope in 2013 to determine the source redshift. We determine for the first time the redshift of this BL Lac object through the measurement of its host galaxy during low blazar activity. Using the observational evidence that the luminosities of BL Lac host galaxies are confined to a relatively narrow range, we obtain z = 0.18 +/- 0.04. Additionally, we use the Fermi-LAT and MAGIC gamma-ray spectra to provide an independent redshift estimation, z = 0.17 +/- 0.10. Using the former (more accurate) redshift value, we adequately describe the broadband emission with a one-zone SSC model for different activity states and interpret the few-day timescale variability as produced by changes in the high-energy component of the electron energy distribution.Comment: 17 pages, 15 figures, Accepted for publication in A&

Revealing the last 13,500 years of environmental history from the multiproxy record of a mountain lake (Lago Enol, northern Iberian Peninsula)

This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s10933-009-9387-7.We present the Holocene sequence from Lago Enol (43°16′N, 4°59′W, 1,070 m a.s.l.), Cantabrian Mountains, northern Spain. A multiproxy analysis provided comprehensive information about regional humidity and temperature changes. The analysis included sedimentological descriptions, physical properties, organic carbon and carbonate content, mineralogy and geochemical composition together with biological proxies including diatom and ostracod assemblages. A detailed pollen study enabled reconstruction of variations in vegetation cover, which were interpreted in the context of climate changes and human impact. Four distinct stages were recognized for the last 13,500 years: (1) a cold and dry episode that includes the Younger Dryas event (13,500–11,600 cal. year BP); (2) a humid and warmer period characterizing the onset of the Holocene (11,600–8,700 cal. year BP); (3) a tendency toward a drier climate during the middle Holocene (8,700–4,650 cal. year BP); and (4) a return to humid conditions following landscape modification by human activity (pastoral activities, deforestation) in the late Holocene (4,650–2,200 cal. year BP). Superimposed on relatively stable landscape conditions (e.g. maintenance of well established forests), the typical environmental variability of the southern European region is observed at this site.The Spanish Inter-Ministry Commission of Science and Technology (CICYT), the Spanish National Parks agency, the European Commission, the Spanish Ministry of Science, and the European Social Fund

The Cherenkov Telescope Array Large Size Telescope

The two arrays of the Very High Energy gamma-ray observatory Cherenkov Telescope Array (CTA) will include four Large Size Telescopes (LSTs) each with a 23 m diameter dish and 28 m focal distance. These telescopes will enable CTA to achieve a low-energy threshold of 20 GeV, which is critical for important studies in astrophysics, astroparticle physics and cosmology. This work presents the key specifications and performance of the current LST design in the light of the CTA scientific objectives.Comment: 4 pages, 5 figures, In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.223