31. Arbuscular mycorrhizal fungi alter Hg root uptake and ligand environment as studied by X-ray absorption fine structureAlojz Kodre, Iztok Arčon, Marta Debeljak, Mateja Potisek, Matevž Likar, Katarina Vogel-Mikuš, 2017, izvirni znanstveni članek Opis: Mercury (Hg) – plant – fungal interactions are only poorly studied. Hg speciation and ligand environment
in maize roots inoculated with arbuscular mycorrhizal (AM) fungi were investigated in order to better
understand the role of AM in Hg soil to root transfer.
The maize plants were grown in Hg polluted substrate (50 mg g1 as dissolved HgCl2) and inoculated
with AM fungi originating from: a) highly Hg polluted environment of a former Hg smelting site in Idrija,
Slovenia, (Glomus sp. – sample AmI), and b) non-polluted environment (commercial AM inoculum
Symbivit1 – sample AmC). Hg speciation and ligand environment in maize roots was studied by Hg-L3
XANES and EXAFS with emphasis on XAS methodology – modelling and fitting the XAFS spectra to extract in a reliable way as much information on Hg coordination as possible. The AmI plants developed more arbuscules and less vesicles than the AmC plants, and also
accumulated more Hg in the roots. A clear difference in Hg coordination between the AM (AmC & AmI)
and the control (ConC & ConI) plants is recognized in Hg L3-edge EXAFS analysis: in the ConC & ConI
maize roots 73–80% of Hg is attached between two sulphur atoms at the distance of 2.34 Å. The remaining
ligand is nitrogen at 2.04 Å. In AmI & AmC roots another Hg-S attachment encompassing four thiol groups
at the S-distance of 2.50 Å are identified, accounting for 21–26%. AM fungi can modify Hg ligand environment in plant roots, thus playing an important role in biogeochemical cycling of Hg in terrestrial
ecosystems.
Ključne besede: EXAFS
XANES
Arbuscular mycorrhiza
Phytoremediation
Toxicity
Hg coordination
Ligand environment
Objavljeno v RUNG: 27.09.2016; Ogledov: 6208; Prenosov: 0
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32. XAS and micro-XRF analysis of mono and bi-metallic exopolysaccharide (FePd-EPS) bio-generated by K. oxytocaIztok Arčon, Stefano Paganelli, Oreste Piccolo, Michele Gallo, Katarina Vogel-Mikuš, Franco Baldi, 2016, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Bacteria Klebsiella oxytoca (DSM 29614) secret a specific exopolysaccharide (EPS) in the presence of Fe(III)-citrate, as sole carbon and energy source, and produces after 7 days an iron gel precipitate (Fe-EPS) [1]. In the presence of palladium or other metal species, the culture of K. oxytoca can produce other mono or bimetal species (Pd-EPS, FePd-EPS) [2]. These bio-materials may be used as green biogenerated catalysts or for other biotechnological purposes. In this work we present the analysis of the morphology and the chemical state of the metals in mono and bi-metallic (Fe-EPS, Pd-EPS, FePd-EPS) complexes, by a combination of micro X-ray fluorescence, X-ray absorption spectroscopy methods (XANES and EXAFS), and transmission electron microscopy. The results show that iron in monometallic Fe-EPS and bimetalic FePd-EPS is in the mineralized form of iron oxides/hydroxides, predominantly in the form of Fe3+, with a small amount of Fe2+ in the structure, as a mixture of different nano-crystalline iron oxides and hydroxides. Palladium on the other hand is found as Pd(0) in the form of metallic nanoparticles with fcc structure in both, bi-metallic (FePd-EPS) and mono-metallic (Pd-EPS) species. In bi-metallic species Pd and Fe nanoparticles agglomerate in larger clusters, but they remain spatially separated. Access to the SR facilities at ESRF (beamline ID21, project LS-2225), DESY (beamline C) Hamburg (project I-20110511 EC) and ELETTRA (beamline XAFS, project 20115112) is acknowledged.
Ključne besede: Klebsiella oxytoca, Fe, Pd, XANES, EXAFS, exopolysaccharide, FePd-EPS
Objavljeno v RUNG: 28.06.2016; Ogledov: 5577; Prenosov: 0
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36. Ustno izročilo in kulturni spomin v zgornjem ObsoteljuKatarina Šrimpf, 2015, doktorska disertacija Opis: Doktorska disertacija z naslovom Ustno izročilo in kolektivni spomin v zgornjem Obsotelju je celovita študija pripovednega izročila zgornjega Obsotelja, območja na slovenskem etničnem ozemlju. V uvodu prinaša predstavitev območja in krajev v treh raziskovanih občinah z zgodovinskega, gospodarskega pa tudi družbenega in kulturnega vidika ter predstavitev gradiva, tako starejšega, ki je bilo zbrano s pomočjo arhivskega dela, kot tudi novejšega, ki je bilo zbrano s terenskim delom. Gradivo je opisano in analizirano skozi žanrsko in tematsko strukturo. Drugi del disertacije je osredotočen na pomen in vlogo, ki jo imajo izbrani elementi pripovednega izročila v družbenem in kulturnem življenju obravnavanega območja. Kot ključni elementi za razumevanje pomena in vloge pripovedništva so se pokazali trije kriteriji: 1) percepcija prostora in časa, 2) konstruiranje identitet, 3) sodobna raba pripovedi in njihovih funkcij. Prostor in čas, kot se kažeta skozi pripovedno izročilo, sta koncipirana s pomočjo liminalnega časa in prostora ter etioloških povedk in zgodovinskih zgodb. Šaljive zgodbe o Lemberžanih ter zbadljivke in druge zgodbe o Hrvatih so v zgornjem Obsotelju priročno sredstvo za ločevanje ene skupine od druge, kar omogoča konstruiranje tako lokalnih kot nacionalnih in drugih identitet. Funkcijo vzbujanja občutka lokalne pripadnosti in vzpostavljanja lokalne identitete ima tudi sodobna raba lokalnega pripovednega izročila, ki je vzeto iz primarnega okolja. Poskus razumevanja pomenov in funkcij, ki jih ima ustno izročilo v lokalnem okolju, je glavna tema te disertacije.
Ključne besede: ustno izročilo, pripovedništvo, zgornje Obsotelje, percepcija prostora in časa, ustvarjanje identitet
Objavljeno v RUNG: 04.12.2015; Ogledov: 6514; Prenosov: 347
 Celotno besedilo (5,95 MB) |
37. Radioactive isotopes in ground waters of SloveniaKatarina Kovačič, 2015, doktorska disertacija Opis: Within the duration of three projects (J7-0363, L1-0437, L1-4280), in the period from 2008 to 2013, measurements of tritium (3H), 40K and γ-ray emitters of uranium (238U, 226Ra and 210Pb) and thorium (228Ra and 228Th) decay series in groundwaters of Slovenia were carried out. Tritium was also measured in precipitation at selected locations. Groundwater sampling sites were selected in order to cover the most representative lithological units that are found in Slovenia and were at the same time evenly distributed throughout the country. In total, 281 samples were measured from 120 different locations.
Measurements in the period 2009-2013 have shown that tritium concentrations in precipitation in Ljubljana are for about 30% lower compared to those in Vienna, however they are in line with seasonal fluctuations observed in Vienna. This was an important information in the process of the reconstruction of past tritium concentrations in precipitation in Ljubljana (tritium curve) for the missing period between 1953 and 1981. Tritium curve represents the input data when determining the average age of water.
In determining the influence of various parameters on the final interpretation of the groundwater age it has been found that the greatest uncertainty contribute the measurements of the tritium curve and the measurements of tritium in groundwater samples. Also, the interaction of other factors (continental effect, rainfall regime, infiltration) and the lack of knowledge of them may have a major impact on the misinterpretation of groundwater age.
Based on tritium concentration, groundwaters were divided into 4 major categories, into groundwaters that are older than 100 years (tritium concentration was below the detection limit), groundwaters, where the older component prevails (concentration of tritium was between 0 and 2.5 TU), groundwaters with the age between 30 and 60 years (the concentration of tritium was on average 8 TU) and recent groundwaters with age up to 15 years (tritium concentration of about 6 TU).
The natural background of γ-ray emitters was determined for each lithological unit. The most represented radionuclide was 40K with concentrations always above the detection limit. A dependency of 40K concentrations on nitrate was observed, especially in the recharge areas, where limestone prevailed. Other γ-ray emitters revealed some dependence on nitrate concentration, especially both radium isotopes (226Ra and 228Ra). The concentration of 210Pb in groundwaters is mainly due to the connection with the surface and consequently with atmospheric 210Pb. The highest concentrations of 238U and 228Ra were measured in groundwaters from recharge areas in clastic rocks with a clay component. In contrast to the expected, concentrations for all γ-ray emitters (except 210Pb) were the lowest or even not detectable, in groundwaters from recharge areas in igneous and metamorphic rocks.
Among γ-ray emitters and categorization based on tritium concentrations, elevated concentrations of 238U were observed in groundwaters with prevailing older component. Elevated concentrations of 40K were also observed in them. The largest scattering of 210Pb and 40K concentrations was observed in recent waters, which indicates a connection with the surface and application of fertilizers.
Ključne besede: Groundwaters, Slovenia, tritium input curve, natural gamma-ray emitters background.
Objavljeno v RUNG: 05.10.2015; Ogledov: 6319; Prenosov: 210
Celotno besedilo (8,62 MB) |
38. Podoba moje vasi - agrarne razmere na Črnovrškem v 19. stoletjuKatarina Rudolf, 2015, diplomsko delo Opis: Predmet raziskave diplomskega dela je individualna kmečka posest na primeru Črnega Vrha nad Idrijo v 19. stoletju. V teoretičnem delu sem obravnavala individualno kmečko posest ter razložila posamezne pojme povezane z njo. Predstavila sem strukturo kmečke posesti in socialno podobo Črnega Vrha tistega časa. Temeljno gradivo, ki sem ga uporabila, je franciscejski kataster.
Ključne besede: Individualna kmečka posest, Črni Vrh nad Idrijo, 19. stoletje, franciscejski kataster, pašnik, travnik, njiva.
Objavljeno v RUNG: 17.09.2015; Ogledov: 5224; Prenosov: 285
Celotno besedilo (2,40 MB) |
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40. Modelling of continuous casting of steel under the influence of electromagnetic field with meshless method : dissertationKatarina Mramor, 2014, doktorska disertacija Ključne besede: kontinuirano ulivanje jekla, laminarni tok, turbulentni tok, naravna konvekcija, prisilna konvekcija, strjevanje, magnetno polje, sklopljeni sistemi, večfizikalni problemi, brezmrežne metode, kolokacija, multikvadriki, radialne bazne funkcije, eksplicitna časovna shema, metoda delnih korakov, verifikacija, simulacija, kontinuirno vlivanje jekla
Objavljeno v RUNG: 22.01.2015; Ogledov: 5571; Prenosov: 268
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