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The mechanism of Li2S activation in lithium-sulfur batteries: Can we avoid the polysulfide formation?
Robert Dominko, Tim-Patric Fellinger, Markus Antonietti, Giuliana Aquilanti, Lorenzo Stievano, Iztok Arčon, Elena Tchernychova, Laurent Chabanne, Alen Vižintin, 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.
Najdeno v: osebi
Ključne besede: Lithium-sulfur batteries Li2S active material XAS UV/Vis spectroscopy Li2S activation
Objavljeno: 03.03.2017; Ogledov: 2142; Prenosov: 0
.pdf Polno besedilo (2,98 MB)

An extracellular polymeric substance quickly chelates mercury(II) with N-heterocyclic groups
Claudia Faleri, Dario Battistel, Salvatore Daniale, Michele Gallo, Franco Baldi, 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.
Najdeno v: osebi
Ključne besede: Klebsiella oxytoca, Biosorption, Proteins, Polysaccharide, Cyclic voltammetry, EXAFS analysis
Objavljeno: 03.03.2017; Ogledov: 1731; Prenosov: 0
.pdf Polno besedilo (1,66 MB)

Biotransformation of copper oxide nanoparticles by the pathogenic fungus Botrytis cinerea
Katarina Vogel-Mikuš, Darko Makovec, Tamás Papp, Iztok Arčon, Johannes Teun van Elteren, Marjana Regvar, Eva Kovačec, 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.
Najdeno v: osebi
Ključne besede: copper, metal oxide nanoparticles, detoxification mechanisms, metal pollution, Cu-oxalate
Objavljeno: 23.08.2017; Ogledov: 1305; Prenosov: 0
.pdf Polno besedilo (1,52 MB)

Electrochemical dissolution of iridium and iridium oxide particles in acidic media
Miran Gaberšček, Samo B. Hočevar, Vid Simon Šelih, Martin Šala, Marjan Bele, Milena Zorko, Barbara Jozinović, Iztok Arčon, Francisco Ruiz-Zepeda, Nejc Hodnik, Primož Jovanovič, 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.
Najdeno v: osebi
Ključne besede: Iridium Oxide Par-ticles, Electrochemical Dissolution of Iridium, Ir L3-edge XANES
Objavljeno: 23.08.2017; Ogledov: 1073; Prenosov: 0
.pdf Polno besedilo (1,43 MB)

Correlations between photocatalytic activity and Cu structure in Cu-modified TiO2-SiO2
T. Čižmar, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: osebi
Ključne besede: Titanium dioxide, Cu-modified, TiO2-SiO2, photocatalysts, photocatalytic activity, Cu K-edge XANES, EXAFS
Objavljeno: 26.06.2017; Ogledov: 1455; Prenosov: 0
.pdf Polno besedilo (641,42 KB)

Chemical structure in Cu-modified TiO2-SiO2 nanocomposites calcined at 500 °C for 1 h in air
T. Čižmar, Iztok Arčon, Urška Lavrenčič Štangar, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: osebi
Ključne besede: Cu-modified TiO2-SiO2 photocatalysts, titanium dioxide, metal doping, Cu K-edge XANES, EXAFS, photocatalytic activity
Objavljeno: 22.08.2017; Ogledov: 11090; Prenosov: 0
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Edge profiles in K shell photoabsorption spectra of gaseous hydrides of 3p elements and homologues
Giuliana Aquilanti, Alojz Kodre, Iztok Arčon, Robert Hauko, Jana Padežnik Gomilšek, 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.
Najdeno v: osebi
Ključne besede: X-ray absorption spectra, gaseous hydrides, 3p K-edge spectra, DFT
Objavljeno: 23.08.2017; Ogledov: 1102; Prenosov: 0
.pdf Polno besedilo (703,57 KB)

Role of Surface Cu-O-Zr Sites in the Photocatalytic Activity of TiO2 Nanoscale Particles
Nataša Novak Tušar, Iztok Arčon, Urška Lavrenčič Štangar, Olena Pliekhova, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: osebi
Ključne besede: Photocatalysis, Titanium dioxide, Copper, Zirconia, co-doping, EXAFS, XANES
Objavljeno: 23.08.2017; Ogledov: 1570; Prenosov: 0
.pdf Polno besedilo (426,28 KB)

Structural analysis of sunlight efficient Cu and Zr modified TiO2 photocatalyst
Olena Pliekhova, Iztok Arčon, Urška Lavrenčič Štangar, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: osebi
Ključne besede: TiO2, photocatalysis, EXAFS, surface modification
Objavljeno: 23.08.2017; Ogledov: 1399; Prenosov: 0
.pdf Polno besedilo (577,74 KB)

Contribution of Cu and Zr to the Properties of TiO2 for Photocatalytic Water Treatment
Olena Pliekhova, Iztok Arčon, Nataša Novak Tušar, Urška Lavrenčič Štangar, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: osebi
Ključne besede: Photocatalysis, water treatment, surface modification, durability
Objavljeno: 23.08.2017; Ogledov: 1505; Prenosov: 0
.pdf Polno besedilo (509,62 KB)

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