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4863. Muon counting using silicon photomultipliers in the AMIGA detector of the Pierre Auger observatoryA. Aab, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, izvirni znanstveni članek Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays (UHECR), extensive air showers (EAS), EAS muon content, Auger Muons and Infill for the Ground Array (AMIGA), scintillation modules for muon counting, silicon photomultipliers (SiPM) Objavljeno v RUNG: 08.03.2017; Ogledov: 4334; Prenosov: 1 Gradivo ima več datotek! Več... |
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4867. An extracellular polymeric substance quickly chelates mercury(II) with N-heterocyclic groupsFranco Baldi, Michele Gallo, Salvatore Daniale, Dario Battistel, Claudia Faleri, Alojz Kodre, Iztok Arčon, 2017, izvirni znanstveni članek Opis: A strain of Klebsiella oxytoca DSM 29614 is grown on sodium citrate in the presence of 50 mg l−1 of Hg as Hg(NO3)2. During growth, the strain produces an extracellular polymeric substance (EPS), constituted by a mixture of proteins and a specific exopolysaccharide. The protein components, derived from the outer membrane of cells, are co-extracted with the extracellular exopolysaccharide using ethanol. The extracted EPS contains 7.5% of Hg (total amount). This indicates that EPS is an excellent material for the biosorption of Hg2+, through chemical complexation with the EPS components. The binding capacity of these species towards Hg2+ is studied by cyclic voltammetry, and Hg L3-edge XANES and EXAFS spectroscopy. The results found indicate that Hg2+ is mainly bound to the nitrogen of the imidazole ring or other N-heterocycle compounds. The hydroxyl moities of sugars and/or the carboxyl groups of two glucuronic acids in the polysaccharide can also play an important role in sequestring Hg2+ ions. However, N-heterocyclic groups of proteins bind Hg2+ faster than hydroxyl and carboxyl groups of the polysaccharide. Ključne besede: Klebsiella oxytoca, Biosorption, Proteins, Polysaccharide, Cyclic voltammetry, EXAFS analysis Objavljeno v RUNG: 03.03.2017; Ogledov: 4720; Prenosov: 0 Gradivo ima več datotek! Več... |
4868. The mechanism of Li2S activation in lithium-sulfur batteries: Can we avoid the polysulfide formation?Alen Vižintin, Laurent Chabanne, Elena Tchernychova, Iztok Arčon, Lorenzo Stievano, Giuliana Aquilanti, Markus Antonietti, Tim-Patric Fellinger, Robert Dominko, 2017, izvirni znanstveni članek Opis: Electrochemical reactions in the LieS batteries are considered as a multistep reaction process with at least
2e3 equilibrium states. Here we report a possibility of having a conversion of Li2S into sulfur without
detectible formation of polysulfides. That was confirmed by using a novel material system consisting of
carbon coated Li2S particles prepared by carbothermal reduction of Li2SO4. Two independent in operando
measurements showed direct oxidation of Li2S into sulfur for this system, with almost negligible formation
of polysulfides at potentials above 2.5 V vs. Li/Liþ. Our results link the diversity of first charge profiles in the
literature to the Li2S oxidation mechanism and show the importance of ionic wiring within the material.
Furthermore, we demonstrate that the Li2S oxidation mechanism depends on the relative amount of
soluble sulfur in the electrolyte. By controlling the type and the amount of electrolyte within the encapsulating
carbon shell, it is thereby possible to control the reaction mechanism of Li2S activation. Ključne besede: Lithium-sulfur batteries
Li2S active material
XAS
UV/Vis spectroscopy
Li2S activation Objavljeno v RUNG: 03.03.2017; Ogledov: 5239; Prenosov: 0 Gradivo ima več datotek! Več... |
4869. Operando characterization of batteries using x-ray absorption spectroscopy: advances at the beamline XAFS at synchrotron ElettraGiuliana Aquilanti, marco Giorgetti, Robert Dominko, Lorenzo Stievano, Iztok Arčon, Nicola Novello, Luca Ivanc Olivieri, 2017, izvirni znanstveni članek Opis: X-ray absorption spectroscopy is a synchrotron radiation based technique that is able to
provide information on both local structure and electronic properties in a chemically selective
manner. It can be used to characterize the dynamic processes that govern the electrochemical
energy storage in batteries, and to shed light on the redox chemistry and changes in structure
during galvanostatic cycling to design cathode materials with improved properties. Operando
XAS studies have been performed at beamline XAFS at Elettra on different systems. For
Li-ion batteries, a multiedge approach revealed the role of the different cathode components
during the charge and discharge of the battery. In addition, Li-S batteries for automotive
applications were studied. Operando sulfur K-edge XANES and EXAFS analysis was used to
characterize the redox chemistry of sulfur, and to relate the electrochemical mechanism to its
local structure. Ključne besede: operando studies, x-ray absorption spectroscopy, Li-ion batteries, Li-S batteries Objavljeno v RUNG: 03.03.2017; Ogledov: 6214; Prenosov: 0 Gradivo ima več datotek! Več... |
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