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1.
Prisotnost mikroplastike in njena pestrost v vodnem stolpcu in školjkah klapavicah (Mytilus galloprovincialis) iz školjčišč slovenskega morja
Irma Hostnik, 2023, master's thesis

Abstract: V magistrskem delu smo želeli ugotoviti, katera lokacija v slovenskem morju je najbolj primerna za intenzivno gojenje školjk klapavic (Mytilus galloprovincialis) s stališča prisotnosti mikroplastike in na kateri globini so klapavice najmanj podvržene njenemu vplivu. Analizirali smo mikroodpadke, vključujoč mikroplastiko, v vzorcih morske vode ter školjkah iz školjčišč na Debelem rtiču, Seči in Strunjanu. Morsko vodo smo vzorčili z bencinsko črpalko ter na plovilu filtrirali prečrpano vodo na situ s porami 100 µm (vzorčenje in-situ). Na posameznem vzorčnem mestu smo prečrpali tri paralelne vzorce 1 m3 morske vode na dveh globinah. Skupno smo analizirali filtrate 18 m3 morske vode. Poleg morske vode smo na globini vzorčenja vode odvzeli školjke klapavice, in sicer petdeset školjk na posamezni globini. Analizirali smo torej skupno tristo školjk, sto školjk iz vsakega od treh školjčišč. Prisotnost mikroodpadkov in mikroplastike smo potrdili v vseh vzorcih vode. Z najvišjimi koncentracijami mikroodpadkov je izstopala zgornja vzorčna plast školjčišča na Debelem rtiču. Mikroodpadke smo našli v kar 75,7 % školjk. Najvišje povprečno število mikroodpadkov na školjko smo ugotovili pri školjkah iz školjčišča v Strunjanu.
Keywords: mikroplastika, vodna črpalka, školjke, vodni stolpec, morje, koncentracija mikroodpadkov, koncentracija mikroplastike, FTIR
Published in RUNG: 09.10.2023; Views: 639; Downloads: 12
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2.
Removal of copper from aqueous solutions with zeolites and possible treatment of exhaust materials
Nataša Zabukovec Logar, Iztok Arčon, Janez Kovač, Margarita Popova, 2021, original scientific article

Abstract: The mechanism of Cu2+ loading into commercially available natural HEU-type and synthetic LTA-type zeolites for their possible use in environmental processes, such as water and air treatment applications, was studied. Elemental analysis, SEM/EDXS, XRD, XAS and XPS analyses revealed 4-fold coordination of Cu2+ cations with oxygen atoms in the pores, a predominant location of copper atoms on the surface of crystallites and retained crystallinity of zeolites throughout the processes. The post-treatment of Cu2+-loaded samples with HCl and/or NaCl solutions confirmed the predominantly reversible sorption of copper on zeolites from aqueous solutions by ion-exchange mechanism and, therefore, excellent regeneration possibilities for both types of zeolites. Furthermore, with the calcination of exhaust metal-loaded zeolites, catalysts for total toluene oxidation reaction, as a model VOC pollutant, were obtained.
Keywords: Cu2+ ion exchange, Total toluene oxidation, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, Zeolite
Published in RUNG: 03.06.2021; Views: 1897; Downloads: 153
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3.
Effect of the Morphology of the High-Surface-Area Support on the Performance of the Oxygen-Evolution Reaction for Iridium Nanoparticles
Leonard Moriau, Marjan Bele, Živa Marinko, Francisco Ruiz-Zepeda, Gorazd Koderman, Martin Šala, Angelija Kjara Šurca, Janez Kovač, Iztok Arčon, Primož Jovanovič, Nejc Hodnik, Luka Suhadolnik, 2021, original scientific article

Abstract: The development of affordable, low-iridium-loading, scalable, active, and stable catalysts for the oxygen-evolution reaction (OER) is a requirement for the commercialization of proton-exchange membrane water electrolyzers (PEMWEs). However, the synthesis of high-performance OER catalysts with minimal use of the rare and expensive element Ir is very challenging and requires the identification of electrically conductive and stable high-surface-area support materials. We developed a synthesis procedure for the production of large quantities of a nanocomposite powder containing titanium oxynitride (TiONx) and Ir. The catalysts were synthesized with an anodic oxidation process followed by detachment, milling, thermal treatment, and the deposition of Ir nanoparticles. The anodization time was varied to grow three different types of nanotubular structures exhibiting different lengths and wall thicknesses and thus a variety of properties. A comparison of milled samples with different degrees of nanotubular clustering and morphology retention, but with identical chemical compositions and Ir nanoparticle size distributions and dispersions, revealed that the nanotubular support morphology is the determining factor governing the catalyst’s OER activity and stability. Our study is supported by various state-of-the-art materials’ characterization techniques, like X-ray photoelectron spectroscopy, scanning and transmission electron microscopies, Xray powder diffraction and absorption spectroscopy, and electrochemical cyclic voltammetry. Anodic oxidation proved to be a very suitable way to produce high-surface-area powder-type catalysts as the produced material greatly outperformed the IrO2 benchmarks as well as the Ir-supported samples on morphologically different TiONx from previous studies. The highest activity was achieved for the sample prepared with 3 h of anodization, which had the most appropriate morphology for the effective removal of oxygen bubbles.
Keywords: electrocatalysis, oxygen-evolution reaction, TiONx-Ir powder catalyst, iridium nanoparticles, anodic oxidation, morphology−activity correlation
Published in RUNG: 04.01.2021; Views: 2479; Downloads: 0
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4.
5.
Map of revisionist monuments
Gal Kirn, Elvis Krstulović, Iva Kovač, exhibition

Keywords: historical revisionism, East Europe, anti-communism, new monuemnts, rehabilitation of fascism
Published in RUNG: 18.09.2020; Views: 2302; Downloads: 0
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6.
Prevzeto izrazje s področja popularnih glasbenih zvrsti in njegova slovarska obravnava
Petra Kovač, 2019, undergraduate thesis

Abstract: Diplomska naloga obravnava problematiko pisanja prevzetega besedja v slovenskem jeziku. V uvodnem delu se bom najprej posvetila obravnavi problematike prevzemanja besed, načinu prevzemanja v slovenski jezikovni sistem in predstavila tudi historični vidik prevzemanja slovenskih prevzetih besed in besednih zvez. Osrednji del diplomskega dela bo osredotočen na besedje s področja glasbe, zlasti prevzemanje izrazov, povezanih s popularno glasbo. V svojem delu želim ugotoviti, v kateri obliki se posamezni izrazi dejansko uporabljajo, v nepodomačeni ali podomačeni, pri čemer lahko soobstaja več podomačenih različic. S pomočjo korpusa Gigafida bom naredila analizo, s katero bo ugotovljeno, v kolikšni meri jezikovni uporabniki upoštevajo določila normativnih priročnikov glede pisanja prevzetih besed oziroma nasprotno, ali ta pravopisna določila sledijo rabi, ki jo uveljavljajo jezikovni uporabniki. Cilj diplomskega dela je prikazati glavne jezikovne zadrege uporabnikov slovenskega jezika pri zapisovanju besed s področja glasbe, ki smo jih v slovenski jezik prevzeli iz drugih jezikov, in ta opažanja tudi pojasniti.
Keywords: Podomačevanje, prevzete besede, glasbene zvrsti
Published in RUNG: 26.09.2019; Views: 3304; Downloads: 140
.pdf Full text (1,61 MB)

7.
Speleogenetic factors and processes in the karst conduits of Zagorska Mrežnica Spring Cave (Croatia)
Petra Kovač Konrad, 2018, doctoral dissertation

Abstract: Zagorska Mrežnica spring cave is in the Desmerice village, 7.59 km SW from the town of Ogulin. The coordinates of the entrance are X: 399563 m, Y: 5006974 m, and Z: 314 m (HTRS96). The cave system is positioned in the contact zone of Jurassic limestone and the thrust front composed of Triassic Dolomite. The karst drainage system has elements of point recharge through a set of ponors in the hinterland karst poljes and diffuse infiltration through numerous dolines on Velika Kapela Mountain. The karst of Ogulinsko Zagorje area and its epiphreatic and phreatic cave systems have been intensively explored for the last eight years, resulting in the mapping of 1134 m of submerged passages of the Zagorska Mrežnica spring cave. Until 2014 it was the longest mapped submerged system in Croatia explored by cave diving techniques only. Altogether, over 3.5 km of submerged passages in seven caves of Ogulinsko Zagorje (Zagorska Mrežnica spring cave, Spring of Rupečica, Ponor of Rupečica, Cave system Pećine-Veliko vrelo, Spring of Bistrac, Cave Zagorska Peć and Pit Klisura) were explored during 500 hours of diving over a ten-year period. The goal of the research was to determine speleogenetic factors and processes in phreatic conditions. A new methodology for mapping of cave cross-sections, microrelief forms, and structural elements was developed, sediment and petrographic analysis were done, hydrological analysis before and after the building of the accumulation lake Sabljaci, 48 cross-sections of the cave passaged and a 3D model of the cave system was created, water chemistry as well as geomorphological analysis was carried out. In the end, a simplified (modified) vulnerability assessment was also done. The results of my research showed that the distribution of the cave passages is a result of complex tectonic activities that are reflected in the orientation of cave passages. The general orientation of the measured fissures, measured during cave diving, show a dominance of a NWW-SEE direction but also the pattern of cave passages shows a significant dominance of the NE-SW orientation indicating the existence of multiple secondary traverse faults originating from main NW-SE faults. The morphology of the cave passages shows a transition between epiphreatic (possibly vadose) and phreatic phases as well as the presence of paragenetic developments in the ceiling. This indicates the existence of several epiphreatic (possibly vadose) and phreatic speleogenetic phases. The initial shape of the cross-sections was identified by sub-horizontal beds and bedding planes. The mapping of microrelief forms showed that the mechanical erosion was a very intensive process shaping the morphology of the cave passages. The sediment mineralogy coincides with the lithology of the catchment area, and the sub- angular grains reveal relatively short transport distances. Further analysis of the catchment area’s geomorphology and its relevance for the speleogenesis of Zagorska Mrežnica cave show influence of relief structures that have a Dinaric orientation (NW-SE) with cave structures and passage orientations, great relative relief, steep slopes on Velika Kapela, and flat areas of karst poljes dictate the allogenic and autogenic hydrological regime of the cave. A 3D model of the cave system reveals a relationship between the cave system and the landscape, as well as a possible connection with the nearby Zagorska Peć cave. The modified karst vulnerability assessment shows that the catchment area of Zagorska Mrežnica spring cave has a high vulnerability ranking, mainly due to high doline density and the potential large diffuse capacity of infiltration of pollutants.
Keywords: Ogulin Zagorje, karst, spring, speleogenesis, Zagorska Mrežnica spring cave
Published in RUNG: 02.03.2018; Views: 4851; Downloads: 196
.pdf Full text (5,26 MB)

8.
Anketa o delu in življenju sodobnih slovenskih literarnih prevajalk in prevajalcev
2017, interview

Keywords: prevajalci, literarno prevajanje, prevajanje, literatura
Published in RUNG: 21.12.2017; Views: 5154; Downloads: 0
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9.
Extraction of Organochlorine Pesticides from Plastic Pellets and Plastic Type Analysis
Maryline Pflieger, Petra Makorič, Manca Kovač Viršek, Špela Koren, 2017, review article

Abstract: Plastic resin pellets, categorized as microplastics (≤5 mm in diameter), are small granules that can be unintentionally released to the environment during manufacturing and transport. Because of their environmental persistence, they are widely distributed in the oceans and on beaches all over the world. They can act as a vector of potentially toxic organic compounds (e.g., polychlorinated biphenyls) and might consequently negatively affect marine organisms. Their possible impacts along the food chain are not yet well understood. In order to assess the hazards associated with the occurrence of plastic pellets in the marine environment, it is necessary to develop methodologies that allow for rapid determination of associated organic contaminant levels. The present protocol describes the different steps required for sampling resin pellets, analyzing adsorbed organochlorine pesticides (OCPs) and identifying the plastic type. The focus is on the extraction of OCPs from plastic pellets by means of a pressurized fluid extractor (PFE) and on the polymer chemical analysis applying Fourier Transform-InfraRed (FT-IR) spectroscopy. The developed methodology focuses on 11 OCPs and related compounds, including dichlorodiphenyltrichloroethane (DDT) and its two main metabolites, lindane and two production isomers, as well as the two biologically active isomers of technical endosulfan. This protocol constitutes a simple and rapid alternative to existing methodology for evaluating the concentration of organic contaminants adsorbed on plastic pieces.
Keywords: Environmental Sciences, Issue 125, Microplastics, resin pellets, pesticides, persistent organic pollutants, organochlorine pesticides, dichlorodiphenyltrichloroethane, endosulfan, hexachlorocyclohexane, lindane, Fourier transform infrared spectroscopy, pressurized fluid extractor
Published in RUNG: 10.07.2017; Views: 4380; Downloads: 0

10.
Removal of manganese in batch and fluidized bed systems using beads of zeolite a as adsorbent
Mina Jovanovic, Iztok Arčon, Janez Kovač, Nataša Novak Tušar, Bojana Obradovic, Nevenka Rajić, 2016, original scientific article

Abstract: In this study the uptake capacity of Mn(II) ions by zeolite A beads was investigated for different initial Mn concentration (100e400 mg Mn dm^-3) in batch mode at 25e55 C. The obtained adsorption capacity varying from 30 to 50 mg Mn g^-1 demonstrated a high affinity of zeolite A towards Mn(II) present in solutions. Kinetic studies indicated the intra-particle diffusion as the rate limiting step up to 45 C with apparent diffusivities in the range (1.2e2.0) x 10^-13 m2 s^-1 and the activation energy of 21.9 kJ mol^-1, which implies strong interactions between the zeolite A and Mn ions. At 55 C ion-exchange became the rate limiting step. The adsorption isotherms were studied at 25 C showing that the Mn adsorption is the best described by the Langmuir model suggesting a homogenous zeolite surface. XPS analysis of the Mnloaded beads showed that there is no surface accumulation of Mn but an almost uniform Mn distribution inside zeolite A, whereas XANES and EXAFS suggested that the adsorption of Mn(II) was followed by the Mn(II) oxidation and oxide formation. Regeneration of the spent zeolite was examined in 8 adsorption/desorption cycles by a chelating Na2EDTA in a fluidized column. It has been found that zeolite A beads could be reused for at least 4 cycles with satisfactory Mn(II) adsorption efficiencies of about 70%.
Keywords: Zeolite A Manganese Adsorption kinetics EXAFS/XANES XPS
Published in RUNG: 01.04.2016; Views: 5178; Downloads: 0
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