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71.
Kako lahko z različnimi vrstami svetlobo opazujemo očem nevidni svet okoli nas
Iztok Arčon, vabljeno predavanje na konferenci brez natisa

Opis: Svetloba nam v vsakdanjem žvljenju omogoča, da vidimo in spoznavamo svet okoli nas. Kako zelo je svetloba pomembna za naše življenje opazimo še posebej, če se za nekaj časa znajdemo v popolni temi. In vendar predstavlja vidna svetloba, ki jo lahko zaznajo naše oči, le droben delček v širokem spektru razlčnih vrst svetlobe, ki nam jih ponuja narava. V predavanju si bomo ogledali, kako lahko s svetlobo različnih valovnih dolžin, od infrardeče, preko vidne, ultravijolične in rentgenske svetlobe, opazujemo očem nevidni svet okoli nas. Spomnili se bomo tudi nekaj velikih znastvenih odkritji o svetlobi v zadnjih dvesto letih. Ta osnovna odkritja o lastnostih svetlobe so nam odprla pogled neposredno v svet atomov in danes omogočajo razvoj sodobnih merskih tehnologij na atomski skali. Brez njih si skoraj ne znamo večpredstavljati razvoja novih tehnološko zanimivih materialov in različnih nanotehnologij in različnih raziskav onesnaženja okolja na atomskem nivoju.
Najdeno v: osebi
Ključne besede: rentgesnka svetloba, UV, IR, slikanje, mikroskopiranje, rentgenska absorpcijska spektroskopija
Objavljeno: 01.10.2018; Ogledov: 733; Prenosov: 0
.pdf Polno besedilo (96,06 KB)

72.
ESUO: The European Synchrotron and FEL User Organisation: Aims & Activities
Iztok Arčon, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: The European Synchrotron and free-electron laser (FEL) User Organisation (ESUO) established in 2010 [1] today represents about 30.000 users. We aim at representing the users from all European countries. Each country is represented within ESUO by one up to four national delegate(s), depending on the size of the user community in the respective country. ESUO’s main objectives are (i) to promote an integrated approach throughout Europe for the use of European synchrotron and FEL facilities, (ii) to enable all European scientists to make use of the existing European synchrotron and FEL research infrastructures, solely based on scientific merit of their submitted proposals for beamtime requests, and this independently from the financial situation of the user (country), (iii) to facilitate open transnational access to European light sources through programmes of the European Union, (iv) to disseminate information about scientific opportunities and funding mechanisms for access to synchrotron and FEL facilities, and (v) to be a discussion and acting partner regarding the coordination of the synchrotron and FEL user activities within Europe. In the past few years, ESUO has contributed to several joint activities in the frame of successfully completed European FP7 projects such as ELISA (March 2009 - August 2011) and CALIPSO (June 2012 - May 2015). Some past ESUO activities concern, amongst others:  the user representation in e.g. the CALIPSO and BioStruct-X European projects by ESUO delegates;  the contribution to the CALIPSOplus project application;  the dissemination of ESUO activities by means of e.g. poster presentations and talks delivered at international conferences, specialized user meetings/workshops, and;  several initiatives which have been attended to promote transnational access activities [3] and to favor the continuation of transnational user access to national facilities in Europe within the new European Framework Program Horizon 2020 [4]. Today, chance is given to ESUO to keep constructively acting for the users in the frame of joint networking activities being part of the HORIZON 2020 project CALIPSOplus [5] (May 2017 – April 2021, Grant Agreement No 730872) coordinated by Helmholtz-Zentrum Dresden-Rossendorf (HZDR). In the framework of CALIPSOplus, ESUO is contributing to project networking activities which are, amongst others, shown in the present contribution. With the aim to further prepare the future science at European synchrotron and FEL user facilities, ESUO is contributing to the League of European Accelerator-based Photon Sources (LEAPS) initiative [6].
Najdeno v: osebi
Ključne besede: European synchrotron user organisation, Transnational access, FEL, CALIPSO
Objavljeno: 01.10.2018; Ogledov: 854; Prenosov: 0
.pdf Polno besedilo (149,14 KB)

73.
Cu and Zr surface sites in photocatalytic activity of TiO [sub] 2 nanoparticles
Olena Pliekhova, O. L. Pliekhov, Mattia Fanetti, Iztok Arčon, Nataša Novak Tušar, Urška Lavrenčič Štangar, 2019, izvirni znanstveni članek

Opis: The present work is focused on the role of ZrO2 modification in the performance of CuO modified TiO2. Zirconia loading leads to formation of more resistant photocatalytic layers compared to samples modified with only copper containing species. Surface modification of mixed phase TiO2 with CuO/ZrO2 improves the degradation of Reactive blue 19 dye under simulated solar irradiation. An in-depth investigation of the catalysts showed that in case of CuO/ZrO2 modification, the covering of the TiO2 surface with zirconium containing species prevents morphological and harmful energetic changes induced by copper species formed on the rutile TiO2 phase at a higher copper loading.
Najdeno v: osebi
Ključne besede: titanium dioxide, surface modification, XAS analysis, surface acidity, Hammett indicators
Objavljeno: 26.03.2019; Ogledov: 592; Prenosov: 0
.pdf Polno besedilo (996,21 KB)

74.
Unraveling the arrangement of Al and Fe within the framework explains the magnetism of mixed-metal MIL-100(Al,Fe)
Gregor Mali, Matjaž Mazaj, Iztok Arčon, Darko Hanžel, Denis Arčon, Zvonko Jagličić, 2019, izvirni znanstveni članek

Opis: Properties of mixed-metal MOFs depend on the distribution of different metals within their frameworks. Determination of this distribution is often very challenging. Using an example of aluminum- and iron-containing MIL-100, we demonstrate that 27Al NMR spectroscopy, when combined with first-principles calculations and magnetic, X-band electron paramagnetic resonance, Fe K-edge extended X-ray absorption fine structure, and Mössbauer measurements, enables one to accurately determine the arrangement of Al and Fe within the metal trimers, which are the basic building units of MIL-100. In this particular material, the incorporation of Fe and Al on the framework metal sites is random. Crucial for deciphering the arrangement is detecting NMR signals, shifted because of the strong hyperfine interaction between the 27Al nuclei and the unpaired electronic spins of Fe3+ ions, assigning the shifted signals aided by first-principles calculations of hyperfine couplings, and quantitatively evaluating the NMR intensities and the measured effective magnetic moment.
Najdeno v: osebi
Ključne besede: Fe EXAFS, XANES, MIL100, MOF, magnetizem
Objavljeno: 26.03.2019; Ogledov: 592; Prenosov: 0
.pdf Polno besedilo (2,57 MB)

75.
Synthesis of a Cu/ZnO Nanocomposite by Electroless Plating for the Catalytic Conversion of CO2 to Methanol
Maja Pori, Iztok Arčon, Marjan Marinšek, Goran Dražić, Blaž Likozar, Zorica Crnjak Orel, Damjan Lašič Jurković, 2019, izvirni znanstveni članek

Opis: The process of methanol synthesis based on the hydrogenation of CO2 was investigated over binary Cu/ZnO catalyst materials, prepared by applying a novel electroless plating fabrication method. The activity of the produced catalytic samples was determined at temperature range between 200 and 300 °C and the feedstock conversion data were supplemented with a detailed microstructure analysis using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD) and Cu and Zn K-edge, X-ray absorption near-edge structure (XANES) measurements and extended X-ray absorption fine-structure (EXAFS) measurements. It was confirmed that the disorder in the Cu crystallites created unique geometrical situations, which acted as the additional reactive centres for the adsorption of the reactant molecule species. Copper and zinc structural synergy (spill-over) was also demonstrated as being crucial for the carbon dioxide’s activation. EXAFS and XANES results provide strong evidence for surface alloying between copper and zinc and thus the present results demonstrate new approach applicable for explaining metal–support interactions.
Najdeno v: osebi
Ključne besede: EXAFS, CuZn alloy, Spillover mechanism, CO2 valorization, Electroless deposition method, Heterogeneous catalysis
Objavljeno: 12.04.2019; Ogledov: 653; Prenosov: 0
.pdf Polno besedilo (1,92 MB)

76.
Alternative Recovery and Valorization of Metals from Exhausted Catalytic Converters in a New Smart Polymetallic Catalyst
Oreste Piccolo, Laura Sperni, Michele Gallo, Katarina Vogel-Mikuš, Iztok Arčon, Franco Baldi, Sebastiano Tieuli, Stefano Paganelli, 2019, izvirni znanstveni članek

Opis: A new metals-polymeric composite, Metx-EPS (I), was prepared to be used as catalyst in water or in two-phase aqueous conditions. The metals source was an exhausted catalytic converter that was grinded and treated with an acidic solution at room temperature. After filtration, the solution was concentrated, neutralized and added to a broth of Klebsiella oxytoca DSM 29614 to produce (I) where metals are embedded in a peculiar polysaccharide structure (EPS). The composite was easily recovered from the fermentation broth and purified. The process protocol was verified many times and was shown to be reproducible satisfactorily. The % recovery of metals, originally present in the converter, was good as determined by atomic absorption. The morphology and the chemical state of main metals in (I) were investigated by X-ray absorption spectroscopy methods (XANES and EXAFS). No metallic alloy seems to be evident. The catalytic activity and a possible synergic effect due to the presence of the different metals was valuated in the hydrogenation of some substrates, valuable precursors for theproduction of fine chemicals.
Najdeno v: osebi
Ključne besede: Biogenerated polymetallic exopolysaccharide, biphasic catalysis, hydrogenation, metals-polymeric composite, new catalyst from metallic wastes, EXAFS, XANES
Objavljeno: 06.05.2019; Ogledov: 435; Prenosov: 0
.pdf Polno besedilo (2,87 MB)

77.
A Biogenerated Polymetallic Catalyst from Society's Wastes
Oreste Piccolo, Stefano Paganelli, Petro Zanatta, Sebastiano Tieuli, Laura Sperni, Franco Baldi, Iztok Arčon, Michele Gallo, Katarina Vogel-Mikuš, 2019, izvirni znanstveni članek

Opis: Aims:Preparation of the new metals - polymeric composite, Met x-EPS (I), to be used as a green catalyst in water or in two-phase aqueous conditions. Study Design: Recovery and valorization of polymetallic wastes to obtain directly new catalysts using a microorganism to explore their application in removal of difficult and dangerous chemical pollutants present in aqueous environment
Najdeno v: osebi
Ključne besede: Metals - polymeric composite, biogenerated polymetallic exopolysaccharide, new catalyst from metallic wastes, hydrodechlorination of PCBs in water
Objavljeno: 06.05.2019; Ogledov: 547; Prenosov: 0
.pdf Polno besedilo (373,55 KB)

78.
New Insights into Manganese Local Environment in MnS-1Nanocrystals
Alenka Ristić, Matjaž Mazaj, Iztok Arčon, Nina Daneu, Nataša Zabukovec Logar, Roger Glaser, Nataša Novak Tušar, 2019, izvirni znanstveni članek

Opis: Manganese plays an important role in redox catalysis using zeolites as inorganic support materials, but the formation of the preferred redox manganese species (framework or extraframework) is still not well understood. Herein, the influence of the amount of manganese together with conventional and microwave-assisted hydrothermal synthesis paths on the formation of manganese species within the zeolite silicalite-1 (S-1) with MFI structure was investigated. It was found out that both synthesis procedures led to the formation of framework and extraframework manganese species, but in different molar ratios. However, the conventional synthesis procedure with all Mn/Si molar ratios generates more framework Mn in comparison to the microwave procedure. Additionally, the diminution of the zeolite crystals to nanoscale from 100 to 200 nm was achieved via the conventional procedure for the first time. UV–vis, Raman, and X-ray absorption spectroscopic analyses revealed different local environments of manganese: Mn3+ incorporated into the silicalite-1 framework as “framework manganese” and Mn2+/3+ present as “extraframework manganese” (Mn2O3, Mn3O4). TEM reveals the presence of Mn3O4 nanorods. Both framework manganese and extraframework manganese exhibit good catalytic activity for styrene epoxidation. Catalytic results suggest that, in oxidation reactions of hydrocarbons, framework manganese is more active at lower Mn contents (Mn/Si < 0.015), whereas extraframework manganese is more active at higher loadings (Mn/Si > 0.015).
Najdeno v: osebi
Ključne besede: MnS-1 Nanocrystals, Mn XANES, EXAFS, zeolites, microwave-assisted hydrothermal synthesis
Objavljeno: 06.05.2019; Ogledov: 624; Prenosov: 0
.pdf Polno besedilo (9,33 MB)

79.
80.
Effects of the molecular potential on coexcitations of valence electrons in the K-shell photoeffect of 3p and 4p elements
Robert Hauko, Jana Padežnik Gomilšek, Alojz Kodre, Iztok Arčon, Giuliana Aquilanti, 2019, izvirni znanstveni članek

Opis: Photoabsorption spectra of gaseous hydrides of 3p (PH3, H2S, HCl) and 4p elements (GeH4, AsH3 , H2Se, HBr) are measured in the energy region within 50 eV above the K edge, to study coexcitations of valence electrons by photoeffect in the K shell. The analysis of the valence coexcitations is extended to Ar, Kr, and SiH4. Relative probabilities and energies of states in the individual coexcitation channels are recovered by modeling the spectral features with a minimal ansatz based on the features in the contiguous noble gas. The extracted parameters are compared to the results of theoretical calculations for molecules (ORCA code) and free atoms (Hartree-Fock code). The experimental results confirm that the valence coexcitations in the 3p and 4p hydride molecules can be satisfactorily described by a two-step process, with the shake of the outer electron following the excitation of the core electron. The total probability—relative to the K-edge jump—of the shake-up processes shows a steady decrease from 19% in Si to 14% in Cl, and from 15% in Ge to 12% in Br. The experimental values for Ar (12%) and Kr (10%) are in accord with the trend. The dominant contribution is the transition to quasiatomic orbitals, in contrast with the deeper coexcitation channels in hydride molecules where transition to molecular orbitals prevails.
Najdeno v: osebi
Ključne besede: X-ray absorption spectra, gaseous hydrides, 3p K-edge spectra, DFT
Objavljeno: 05.09.2019; Ogledov: 383; Prenosov: 0
.pdf Polno besedilo (926,96 KB)

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