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112. Biotransformation of copper oxide nanoparticles by the pathogenic fungus Botrytis cinereaEva Kovačec, Marjana Regvar, Johannes Teun van Elteren, Iztok Arčon, Tamás Papp, Darko Makovec, Katarina Vogel-Mikuš, 2017, izvirni znanstveni članek Opis: Two plant pathogenic fungi, Botrytis cinerea and Alternaria alternata, isolated from crop plants, were
exposed to Cu in ionic (Cu2þ), microparticulate (MP, CuO) or nanoparticulate (NP, Cu or CuO) form, in
solid and liquid culturing media in order to test fungal response and toxic effects of the mentioned
compounds for the potential use as fungicides. B. cinerea has shown pronounced growth and lower levels
of lipid peroxidation compared to A. alternata. Its higher resistance/tolerance is attributed mainly to
biotransformation of CuO and Cu NPs and CuO MPs into a blue compound at the fungal/culturing media
interface, recognized by Cu K-edge EXAFS analysis as Cu-oxalate complex. The pronounced activity of
catechol-type siderophores and organic acid secretion in B. cinerea induce leaching and mobilization of
Cu ions from the particles and their further complexation with extracellularly secreted oxalic acid. The
ability of pathogenic fungus to biotransform CuO MPs and NPs hampers their use as fungicides. However
the results show that B. cinerea has a potential to be used in degradation of Cu(O) nanoparticles in
environment, copper extraction and purification techniques.
Ključne besede: copper, metal oxide nanoparticles, detoxification mechanisms, metal pollution, Cu-oxalate
Objavljeno v RUNG: 23.08.2017; Ogledov: 4374; Prenosov: 0
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113. Edge profiles in K shell photoabsorption spectra of gaseous hydrides of 3p elements and homologuesRobert Hauko, Jana Padežnik Gomilšek, Alojz Kodre, Iztok Arčon, Giuliana Aquilanti, izvirni znanstveni članek Opis: Photoabsorption spectra of gaseous hydrides of 3p elements (PH3, H2S, HCl) are measured in the energy region of
photoexcitations pertaining to K edge. The analysis of the edge profile is extended to hydrides of 4p series (GeH4,
AsH3, H2Se, HBr) from an earlier experiment, and to published spectra of 2p hydrides (CH4, NH3, H2O, HF) and
noble gases Ar, Kr and Ne and SiH4. The edge profiles are modelled with a linear combination of lorentzian
components, describing excitations to individual bound states and to continuum. Transition energies and
probabilities are also calculated in the non-relativistic molecular model of the ORCA code, in good agreement
with the experiment. Edge profiles in the heavier homologues are closely similar, the symmetry of the molecule
governs the transitions to the lowest unoccupied orbitals. In 2p series the effect of the strong nuclear potential
prevails. Transitions to higher, atomic-like levels remain very much the same as in free atoms.
Ključne besede: X-ray absorption spectra, gaseous hydrides, 3p K-edge spectra, DFT
Objavljeno v RUNG: 23.08.2017; Ogledov: 3671; Prenosov: 0
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114. Electrochemical dissolution of iridium and iridium oxide particles in acidic media : transmission electron microscopy, electrochemical flow cell coupled to inductively coupled plasma mass spectrometry and X-ray absorption spectroscopy studyPrimož Jovanovič, Nejc Hodnik, Francisco Ruiz-Zepeda, Iztok Arčon, Barbara Jozinović, Milena Zorko, Marjan Bele, Martin Šala, Vid Simon Šelih, Samo B. Hočevar, Miran Gaberšček, 2017, izvirni znanstveni članek Opis: Iridium based particles as the most promising proton exchange membrane electrolyser electrocatalysts were investigated
by transmission electron microscopy (TEM), and by coupling of electrochemical flow cell (EFC) with online inductively
coupled plasma mass spectrometer (ICP-MS). Additionally, a thin-film rotating disc electrode (RDE), an identical location transmission
and scanning electron microscopy (IL-TEM and IL-SEM) as well as an X-ray absorption spectroscopy (XAS) studies have
been performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that iridium
particles dissolved already well below oxygen evolution reaction (OER) potentials, presumably induced by iridium surface oxidation
and reduction processes, also referred to as transient dissolution. Overall, thermally prepared rutile type IrO2 particles (T-IrO2)
are substantially more stable and less active in comparison to as prepared metallic (A-Ir) and electrochemically pretreated (E-Ir)
analogues. Interestingly, under OER relevant conditions E-Ir particles exhibit superior stability and activity owing to the altered
corrosion mechanism where the formation of unstable Ir(>IV) species is hindered. Due to the enhanced and lasting OER performance,
electrochemically pre-oxidized E-Ir particles may be considered as the electrocatalyst of choice for an improved low temperature
electrochemical hydrogen production device, namely a proton exchange membrane electrolyser.
Ključne besede: Iridium Oxide Par-ticles, Electrochemical Dissolution of Iridium, Ir L3-edge XANES
Objavljeno v RUNG: 23.08.2017; Ogledov: 3914; Prenosov: 0
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117. 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: 4663; Prenosov: 0
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118. 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: 5172; Prenosov: 0
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119. 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: 6178; Prenosov: 0
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