Search the repository

A+ | A- | | SLO | ENG

Keywords: prevajalci, literarno prevajanje, prevajanje, literatura
Published in RUNG: 21.12.2017; Views: 5289; Downloads: 0
This document has many files! More...

Abstract: Magistrsko delo obravnava vpliv aerosoliziranih delcev na fiziološki in vnetni odziv makrofagov J774.2. Makrofage smo v prvem delu izpostavili suspenziji filtra z delci črnega ogljika, v drugem delu pa smo postopek izpostavitve ponovili s suspenzijo filtrov, na katere so bili vzorčeni delci iz zunanjega zraka. V obeh primerih smo celice izpostavili različnim koncentracijam suspenzij in analizirali njihov vpliv po 24- urni ali 48- urni inkubaciji. Celično viabilnost smo določili z reagentom PrestoBlue, gensko stabilnost smo ugotavljali z imunofluorescenčno metodo (anti-fosfo-histon H2A.X), oksidativni stres pa smo kvantificirali z barvilom karboksi-H2DCFDA. Vnetni odziv izpostavljenih celic smo opazovali s testom fagocitoze in določanjem citokina TNFα (test ELISA). Rezultati so pokazali, da suspenzija črnega ogljika vpliva na celično živost makrofagov v odvisnosti od koncentracije dodane suspenzije. Dokazali smo povečan nastanek prostih kisikovih radikalov (ROS), znižano gensko stabilnost, ter povečan imunski odziv izpostavljenih celic. Delci črnega ogljika so bistveno povečali obseg fagocitoze in izločanje vnetnega citokina TNFα pri izpostavljenih makrofagih. Pri vseh testih se je odziv večal z višjimi koncentracijami suspenzije črnega ogljika. Rezultati analiz s suspenzijo realnih vzorcev so pokazali, da je vnetni imunski odziv eden prvih odgovorov makrofagov na izpostavljenost okoljskim aerosolom. Opazili smo tudi večje število poškodb DNA izpostavljenih makrofagov, medtem ko je bila viabilnost teh celic še neprizadeta. Na osnovi rezultatov magistrske naloge smo zaključili, da okoljski aerosoli sprožijo vnetni odziv izpostavljenih makrofagov, negativno pa vplivajo tudi na njihovo gensko stabilnost, viabilnost in nastanek ROS. Predvidevamo, da je izraženost učinkov odvisna tudi od koncentracije in sestave okoljskih aerosolov.
Keywords: Makrofagi, črni ogljik, okoljski aerosoli, vnetni odziv, genotoksičnost.
Published in RUNG: 13.10.2017; Views: 5857; Downloads: 286
Full text (1,85 MB)

Abstract: The doctoral dissertation focused on improving photocatalytic activity of nanopowdered ZnO by constructing I) Metal-Semiconductor and II) Semiconductor-Semiconductor heterostructures. Both heterostructure types have been reported to have a beneficial effect on photocatalytic efficiency. For the first part (I) Ag/ZnO nanocomposite was synthesized. Here we investigated an influence of polyvinylpyrrolidone (PVP) addition during the synthesis on the particle properties and their photoactivity. The second part (II) describes procedure development of ZnO based semiconductor-semiconductor composite that resulted in synthesis of highly efficient ZnO/CuWO4 composite. Ag/ZnO nanocomposite was synthesized from precursors in ethylene glycol (EG) in a hydrothermal reactor at 180 °C for 3h. No further thermal treatment was required after the synthesis since all samples showed good crystallinity. Silver precursor loading was 2.7 wt%, because this amount has shown the best photoactivity in preliminary sample testings. Two separate batches of Ag/ZnO nanopowders were prepared, one with addition of PVP, one without (labelled Ag/ZnO and Ag/ZnO*, respectively). All powders were in nanometer range, TEM images showed a major difference between the samples with and without PVP. While Ag nanoparticles were deposited uniformly over ZnO, Ag/ZnO* exhibited a substantial agglomeration of Ag. The photocatalytic efficiency was assessed under UV-Vis light. Ag/ZnO reached complete decolourization of 10–5 M methyl orange (MO) already in 80 min after the beginning of irradiation. The calculated degradation rate constant (k) for the Ag/ZnO was almost 2-times larger than for TiO2 P25 and 4-times larger than for ZnO. Ag/ZnO* also showed higher activity than pure ZnO*, but was inferior to Ag/ZnO (1.6-times of Ag/ZnO*). A reusability test performed on Ag/ZnO showed an excellent photoactivity of reused powders; second and third cycle exhibited higher photoactivity than the first cycle. The supreme photocatalytic activity of Ag/ZnO was also confirmed by degradation of terephthalic acid. To develop an efficient semiconductor-semiconductor heterostructure we have synthesized a combination of several materials with ZnO. We performed preliminary photocatalytic tests in order to assess the functionality of these heterostructures. The tested systems were the following: ZnO/MWCNT, ZnO/GO, ZnO/SiC, ZnO/Co3O4, ZnO/AgVO3. The synthesis of heterostructures was done via hydrothermal synthesis. The commercial or synthesized powers were dispersed together with the ZnO precursor in EG medium (180 °C/3h). The aim was to obtain higher photoactivity than that of pure ZnO. None of these systems was able to outperform pure ZnO. ZnO/CuWO4 system has, however, significantly improved ZnO photoactivity. Several synthesis routes were investigated, including the influence of different structure directing agents (PVP, CTAB, starch). The best performing system was obtained by separate hydrothermal synthesis of ZnO and CuWO4 in water with PVP. XRD analysis confirmed that to obtain the crystalline CuWO4 thermal treatment (500 °C) is needed. The heterostructure was also synthesized in ethanolic solution. ZnO particles were in a nanometer range, CuWO4 were larger and ranged from 200 to 400 nm. CuWO4 has successfully decreased the charge recombination in ZnO, which was confirmed by transient absorption spectroscopy studies. The photocatalytic activity was assessed for both MO and TPA (10–4 M) degradation. The ZnO/CuWO4 composite has completely decolourized the dye in 60 min of UV-Vis irradiation. k for ZnO/CuWO4 was ~2.5-times larger than that of ZnO. A 3-cycle reusability test with MO showed a small decrease in efficiency in the last cycle. TPA degradation has revealed lower efficiency for ZnO/CuWO4 in air but high efficiency in O2 and N2 atmosphere, where it reached 90% and 55% degradation rate, respectively.
Keywords: photocatalysis, zinc oxide, heterostructures, powders, Ag/ZnO composites, ZnO/CuWO4 composites
Published in RUNG: 31.05.2017; Views: 6296; Downloads: 362
Full text (4,11 MB)

Keywords: sluicing, discourse particles, multiple wh-fronting, wh-phrase, left periphery, syntax, Slovenian
Published in RUNG: 14.12.2016; Views: 4750; Downloads: 0
This document has many files! More...

Abstract: How does linguistic structure affect children’s acquisition of early number word meanings? Previous studies have tested this question by comparing how children learning languages with different grammatical representations of number learn the meanings of labels for small numbers, like 1, 2, and 3. For example, children who acquire a language with singular-plural marking, like English, are faster to learn the word for 1 than children learning a language that lacks the singular-plural distinction, perhaps because the word for 1 is always used in singular contexts, highlighting its meaning. These studies are problematic, however, because reported differences in number word learning may be due to unmeasured cross-cultural differences rather than specific linguistic differences. To address this problem, we investigated number word learning in four groups of children from a single culture who spoke different dialects of the same language that differed chiefly with respect to how they grammatically mark number. We found that learning a dialect which features “dual” morphology (marking of pairs) accelerated children’s acquisition of the number word two relative to learning a “non-dual” dialect of the same language.
Keywords: števila, številke, slovnično število, dvojina, narečja, usvajanje, učenje, slovenščina, angleščina, numbers, grammatical number, dual, dialects, acquisition, learning, Slovenian, English
Published in RUNG: 10.08.2016; Views: 5038; Downloads: 244
Full text (1,38 MB)