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1.
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, original scientific article

Abstract: 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.
Found in: ključnih besedah
Keywords: copper, metal oxide nanoparticles, detoxification mechanisms, metal pollution, Cu-oxalate
Published: 23.08.2017; Views: 2429; Downloads: 0
.pdf Fulltext (1,52 MB)

2.
Crystal habit modification of Cu(II) isonicotinate-N-oxide complexes using gel phase crystallisation
Jonathan Steed, Žygimantas Drabavičius, Katja Ferfolja, Dipankar Ghosh, Krishna Kumar Damodaran, 20, original scientific article

Abstract: We report the crystallisation of three forms of copper(II) isonicotinate-N-oxide complex and their phase interconversion via solvent-mediated crystal to crystal transformation. The different forms of copper complex have been isolated and characterised by single crystal X-ray diffraction. Gel phase crystallisation performed in hydrogels, low molecular weight gels and gels of tailored gelator showed crystal habit modification. Crystallisation in aqueous ethanol resulted in concomitant formation of blue (form-I) and green (form-II/IV) crystals while use of low molecular weight gel results in selective crystallization of the blue form-I under identical conditions. Comparison of gel phase and the solution state crystallisation in various solvent compositions reveals that the blue form-I is the thermodynamically stable form under ambient conditions.
Found in: ključnih besedah
Summary of found: ...report the crystallisation of three forms of copper(II) isonicotinate-N-oxide complex and their phase interconversion via...
Keywords: copper(II) complex, gel phase crystallisation, crystal habit modification, isonicotinate-N-oxide, X-ray diffraction
Published: 08.11.2018; Views: 1648; Downloads: 0
.pdf Fulltext (968,24 KB)

3.
Effect of Na, Cs and Ca on propylene epoxidation selectivity over CuOx/SiO2 catalysts studied by catalytic tests, in-situ XAS and DFT
Janvit Teržan, Matej Huš, Iztok Arčon, Blaž Likozar, Petar Djinović, 2020, original scientific article

Abstract: This research focuses on epoxidation of propylene over pristine, Na, Ca and Cs modified CuOx/SiO2 catalysts using O2. The selectivity of the reaction is analyzed using a combination of catalytic tests, in-situ XAS and DFT calculations. The initially present subnanometer CuO clusters are present in all catalysts which re-disperse/flatten during reaction. During catalytic reaction, the Cu1+ becomes the predominant oxidation state. There is no correlation between propylene oxide (PO) selectivity and copper oxidation state. DFT analysis of the propylene reaction pathway revealed that Na, Cs, and Ca addition decreases the bonding strength of propylene to CuO and decreases the O2 activation barrier, while simultaneously increase the exothermicity of O2 dissociation. The Na induced Cu-O bond modification decreases the activation barrier from 0.87 to 0.71 eV for the oxametallacycle (OMC) ring closure (first step in the reaction pathway favoring selectivity towards PO) compared to pristine 5Cu catalyst. At the same time, we observed an increase (from 0.45 to 0.72 eV) of the barrier for the abstraction of allylic hydrogen. The opposite effect is achieved by Ca addition: the activation barrier for OMC ring closure increases to 1.08 eV and that for allylic hydrogen stripping decreases to 0.16 eV.
Found in: ključnih besedah
Summary of found: ...no correlation between propylene oxide (PO) selectivity and copper oxidation state. DFT analysis of the propylene reaction...
Keywords: Alkali modification, propylene epoxidation, reaction mechanism, copper oxide, activation barrier.
Published: 05.06.2020; Views: 1089; Downloads: 0
.pdf Fulltext (22,78 MB)

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