11. Linking root traits to copper exclusion mechanisms in Silene paradoxa L. (Caryophyllaceae)Ilaria Colzi, Sara Pignattelli, Elisabetta Giorni, Alessio Papini, Cristina Gonnelli, 2015, original scientific article Abstract: Copper is one of the most important pollutants in mine- contaminated soils. This study tests the response in a sensitive population vs a tolerant one of the model species Silene paradoxa in order to understand the general mechanisms of tolerance at the micromorphological and ultrastructural level.
Two populations of Silene paradoxa were grown in hydroponics and exposed to different CuSO4 treatments. The roots were investigated with light, fluorescence and transmission electron microscope. Callose and lignin were spectrophotometrically determined.
The tolerant population constitutively possessed a higher amount of mucilage and was able to reduce the length of the zone between the apex and the first lignified tracheids. Callose production decreased. It did not show remarkable copper-induced ultrastructural modifications, apart from the presence of precipitates in the tangential walls. The sensitive population showed huge nucleoli with a spongy periphery in the central cylinder together with the presence of electrondense granules in the mitochondria. Plastids were rarely observed and generally very electrondense and elongated.
In the copper tolerant population of S. paradoxa some of the root traits concurring to generate metal-excluding roots were suggested to be mucilage and lignin production and the reduction of the subapical root zone.
Keywords: Root, Copper exclusion, Lignin, Callose, Tolerance to copper, Silene paradoxa
Published in RUNG: 20.04.2020; Views: 2691; Downloads: 0
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12. Role of Cu current collector on electrochemical mechanism of Mg–S batteryAna Robba, Maja Mežnar, Alen Vižintin, Jan Bitenc, Jernej Bobnar, Iztok Arčon, Anna Randon-Vitanova, Robert Dominko, 2020, original scientific article Abstract: Development of magnesium sulfur battery is accompanied with all known difficulties present in Li–S batteries,
however with even more limited choice of electrolytes. In the present work, the influence of current collector on
electrochemical mechanism was investigated in light of different reports where improved behavior was ascribed
to electrolyte. Notable differences in cycling behavior are reported when Al current collector is replaced by Cu
current collector independent of electrolyte. The initial reduction of sulfur follows similar reaction path no mater
of current collector, but formation of MgS can be in competition with formation of CuS in the presence of Cu
cations. With the subsequent cycling cells prepared from cathodes deposited on Cu current collector show
decrease in the voltage and formation of single plateau during cycling. The change corresponds to the
involvement of Cu into the reaction and formation of redox couple Mg/CuS as determined by Cu K-edge XANES
measurements. Corrosion of Cu foil is identified by SEM and serves as a source of Cu cations for the chemical
reaction between Cu and polysulfides. Mg/CuS redox couple shows improved cycling stability, but theoretical
energy density is severely reduced due to substitution of S with CuS as cathode active material.
Keywords: Magnesium
Sulfur
Rechargeable batteries
Current collector
Copper
Corrosion
Published in RUNG: 16.01.2020; Views: 2977; Downloads: 0
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14. Substrate- to Laterally-Driven Self-Assembly Steered by Cu Nanoclusters: The Case of FePcs on an Ultrathin Alumina FilmManuel Corva, Fatema Mohamed, Erika Tomsič, Zhijing Feng, Tomas Skala, Giovanni Comelli, Nicola Seriani, Maria Peressi, Erik Vesselli, 2018, original scientific article Keywords: copper, nanoclusters, alumina, iron phthalocyanine, Ni3Al
Published in RUNG: 03.12.2019; Views: 2953; Downloads: 0
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15. Zr/Cu-TiO2 CATALYSTS FOR PHOTOCATALYTIC WATER TREATMENTOlena Pliekhova, 2019, doctoral dissertation Abstract: This work entitled «Zr/Cu-TiO2 catalysts for photocatalytic water treatment» tackles a problem of tons of dyes discharged everyday mainly from textile industries. This is a huge concern because of dyes persistence, toxicity and potential to the bioaccumulation in living organisms. Here, a small contribution to overall problem is presented.
The research work consists of three main parts: Theoretical background, Experimental and Results and discussion. In the Theoretical background chapter the overall problem is identified and discussed. The main water treatment techniques are presented briefly with their advantages and drawbacks. Photocatalysis assisted with TiO2 is shown as an alternative additional technique with its own pros and cons. Further, a cursory overview of TiO2 modification techniques is made and advantages in using copper and zirconium oxides for TiO2 modification are presented. The reason and possible positive effect of using of two oxides simultaneously for TiO2 modification is indicated. Additionally, a positive impact of solar light for overall rate of dyes degradation assisted with TiO2 is discussed. Within the framework of photosensitization effect, the problem of using dyes for assessment of photocatalytic properties of materials under the visible light is touched on. Photothermal methods as possible beneficial techniques for this purpose are proposed.
In the Experimental chapter, all experimental techniques used in current research work with the technical details specific for the research work are presented. There are methods of materials preparation, photocatalytic tests under different conditions and varying model pollutants, and physico-chemical characterization techniques.
The Results and discussion chapter is divided by three subchapters. Each chapter is dedicated to one hypothesis, which was checked and confirmed or disproved. The first hypothesis is about beneficial loading of copper and zirconium oxides to TiO2. After numerous experiments held, it was concluded that the pair of copper and zirconium oxides is beneficial for simultaneous application on TiO2 surface to promote its performance.
The second subchapter is about zirconium distribution and its impact on the activity of studied materials towards the antraquinone dye Reactive Blue 19. Different techniques such as XRD, TEM, EXAFS and many others were used in order to characterize the materials and to understand the details of the processes taking place. The existence of upper limit of copper oxide loading for its beneficial effect on TiO2 performance was demonstrated. It was observed that zirconium species loading leads to improvement in performance of materials with higher copper loading, which otherwise lowers activity of TiO2 – this is in case when copper only above its optimal level is present. It was concluded that zirconium oxide containing species occupy rutile surface sites in mixed phase TiO2 and this way beneficially influence the material performance towards the dye removal.
The third subchapter is about the visible light TiO2 assisted dye degradation. It is well known that photosensitization mechanism of dye degradation appears under the visible and as a consequence under the solar light irradiation. This leads to the overall enhancement of dyes degradation, which is positive and may be used as a benefit for faster pollutant destruction. However, this fact leads to mishmash in the determination of real photocatalytic activity of materials towards the dye. It was hypothesized that the impact of photosensitization mechanism on the overall material performance against Reactive blue 19 dye (RB19) descends with the dye concentration lowering. Thermal lens spectrometry (TLS) which is sensitive to chemicals at low concentrations was used for hypothesis evaluation.
To summarize the research work achievements, the conclusions of the thesis are given at the end.
Keywords: titanium dioxide, photocatalysis, zirconium/copper, surface modification, water treatment, dyes
Published in RUNG: 03.12.2019; Views: 5907; Downloads: 136
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16. Crystal habit modification of Cu(II) isonicotinate-N-oxide complexes using gel phase crystallisationDipankar Ghosh, Katja Ferfolja, Žygimantas Drabavičius, Jonathan Steed, 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.
Keywords: copper(II) complex, gel phase crystallisation, crystal habit modification, isonicotinate-N-oxide, X-ray diffraction
Published in RUNG: 08.11.2018; Views: 3330; Downloads: 0
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17. The effect of Zr loading on photocatalytic activity of Cu modified TiO2Olena Pliekhova, O. L. Pliekhov, Mattia Fanetti, Iztok Arčon, Nataša Novak Tušar, Urška Lavrenčič Štangar, 2018, published scientific conference contribution Keywords: Titanium diokside, acidic sites, surface titration, copper, zirconium
Published in RUNG: 10.09.2018; Views: 3844; Downloads: 0
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18. Heavy metal analysis with in-situ prepared copper film electrode as a tool for environmental monitoringNana Ivana Hrastnik, 2017, master's thesis Abstract: Monitoring and measuring heavy metals in the environment is of great importance and requires sensitive and reliable analytical techniques capable of detecting trace level concentrations.
Nowadays, measurements of heavy metals are usually performed using sophisticated and expensive instrumental techniques, such as atomic absorption spectroscopy (AAS), atomic fluorescence spectroscopy (AFS), inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectroscopy (ICP-OES) etc. In this aspect, advanced electroanalytical (stripping) techniques represent a favourable alternative, facilitating sensitive and selective measurements of various analytes using relatively simple, portable and non-expensive instrumentation.
This work is an investigation of novel copper-based electrodes for measuring trace levels of selected heavy metal ions, i.e. mercury(II), lead(II), tin(IV) and nickel(II).
The methods of choice were anodic stripping voltammetry (ASV) in combination with the in-situ prepared copper film electrode (CuFE) for measuring low concentrations of mercury(II) and lead(II) (simultaneously) and tin(IV) in the test solutions and adsorptive cathodic stripping voltammetry (AdCSV) for determination of nickel(II).
Metal-film electrodes are regularly employed in electrochemical stripping analysis due to their simple fabrication and surface regeneration. The newly developed CuFE appears to be a cheaper alternative to gold-based electrodes with several attractive electroanalytical characteristics, i.e. with low limits of detection (LOD), good repeatability and favourable linear response.
Keywords: Copper film electrode, anodic stripping voltammetry, adsorptive cathodic stripping voltammetry, heavy metals, environment.
Published in RUNG: 12.09.2017; Views: 4837; Downloads: 266
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19. Role of Surface Cu-O-Zr Sites in the Photocatalytic Activity of TiO2 Nanoscale ParticlesOlena Pliekhova, Iztok Arčon, Nataša Novak Tušar, Urška Lavrenčič Štangar, 2016, published scientific conference contribution abstract Keywords: Photocatalysis, Titanium dioxide, Copper, Zirconia, co-doping, EXAFS, XANES
Published in RUNG: 23.08.2017; Views: 4628; Downloads: 0
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20. 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, 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.
Keywords: copper, metal oxide nanoparticles, detoxification mechanisms, metal pollution, Cu-oxalate
Published in RUNG: 23.08.2017; Views: 4309; Downloads: 0
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