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Quantification anomalies in single pulse LA-ICP-MS analysis associated with laser fluence and beam size
Ana Jerše, Kristina Mervič, Johannes Teun van Elteren, Vid Simon Šelih, Martin Šala, 2022, izvirni znanstveni članek

Objavljeno v DiRROS: 24.11.2022; Ogledov: 13; Prenosov: 10
.pdf Celotno besedilo (1,39 MB)
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Pristine and ruthenium-doped ▫$TiO_2$▫ nanoclusters for nitrogen reduction reaction : Ab initio study of structure and adsorption
Taja Žibert, Blaž Likozar, Matej Huš, 2023, izvirni znanstveni članek

Objavljeno v DiRROS: 22.11.2022; Ogledov: 30; Prenosov: 22
.pdf Celotno besedilo (1,83 MB)
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Influence of alkalis on the phase development of belite-sulfoaluminate clinkers
Barbara Čeplak, Katarina Šter, Maruša Mrak, Luka Škrlep, Mirijam Vrabec, Sabina Dolenec, 2022, izvirni znanstveni članek

Povzetek: This paper presents a study on the influence of different amounts of alkalis (K2O and Na2O) on clinker phase formation, microstructure, phase composition and reactivity of belite-sulfoaluminate cement clinker. Using X-ray powder diffraction and scanning electron microscopy with energy dispersive spectrometry, it was found that the amount of C2S and C4AF increases with the incorporation of alkalis, while the amount of C4A3Ś and CŚ decreases. In addition to the major phases, the samples with alkalis also consist of minor phases such as C3A (tricalcium aluminate), KŚ (arcanite), and KC2Ś3 (Ca-langbeinite). The major ions in the major phases were substituted by alkali cations and some other ions (Ca2+, Al3+, Fe3+, S2-, S6+, Si4+). The alkalis also affect the microstructure of the clinker, e.g., the shape of the grains. Consequently, isothermal calorimetry was used to detect differences in hydration kinetics. The clinker with 2 wt. % K2O content was the most reactive, while the sample with 0.5 wt. % Na content was the least reactive. The latter was primarily influenced by the content of the main and minor phases of the clinker.
Ključne besede: belite-sulfoaluminate clinker, clinker microstructure, alkalis, reactivity
Objavljeno v DiRROS: 22.11.2022; Ogledov: 37; Prenosov: 10
.pdf Celotno besedilo (4,45 MB)

Preliminary chemical and mineralogical characterization of tailings from base metal sulfide deposits in Serbia and North Macedonia
Timotheus Martin Christoph Steiner, Viktor Bertrandsson Erlandsson, Robert Šajn, Frank Melcher, 2022, izvirni znanstveni članek

Povzetek: Tailings of old mines often contain metals, which were not of economic interest or could not be recovered with the existing technology at the time of active mining. This is especially true for metals that often occur as by-products in Cu-Pb-Zn-(Ag-Au) ores as Sb, Mo, Ge, and In. A fundamental characterization of some tailings is presented in terms of their mineralogy and content of valuable metals which could be extracted to finance a possible remediation and improve the supply of the EU with critical metals. Tailings from active and abandoned mines in Serbia (Bor, porphyry Cu/Au; Krivelj, porphyry Cu/Au; Blagodat, hydrothermal Pb-Zn; Lece, epithermal Au; Rudnik, hydrothermal/skarn Pb-Zn) and North Macedonia (Sasa, Pb-Zn; Probištip, Pb-Zn; Bučim, porphyry Cu; Lojane, fault-bound vein-type low-temperature As, Sb, Cr at the contact of rhyolite and serpentinite) were studied. Analysis for major and trace elements used a multi-method approach (lithium borate fusion and ICP-MS/OES analysis, gravimetric analysis, instrumental neutron activation analysis, total digestion ICP-OES, infrared spectroscopy) with mineral identification by scanning electron microscopy. Concentrations of the major commodity elements (Cu, Pb, Zn, Au, Ag) varies within several orders of magnitude depending on mineralogy and ore type. Critical metals (Co, Ga, Ge, Sb) contents are low with some exceptions. Some tailings contain moderate to elevated potentially toxic element levels (As, Cd, Pb, Tl). For the sample from Probištip which yielded the highest valuable metal concentrations (>5000 ppm Pb, 4020 ppm Zn), a heavy mineral concentrate of the sand size fraction (0.06 mm to 0.5 mm) was produced and analyzed by SEM and LA-ICP-MS for additional rare phases and trace elements. In all tailings studied, additional milling would be needed to separate ore from gangue minerals. Increasing metal prices might facilitate feasibility studies for some of the localities in the future, despite the limited quantitative information about the characterized tailings.
Ključne besede: rudniški odpadki, kemija, mineralogija, rudna nahajališča, sulfidi
Objavljeno v DiRROS: 22.11.2022; Ogledov: 38; Prenosov: 8
.pdf Celotno besedilo (4,76 MB)

Tree rings, wood density and climate–growth relationships of four Douglas-fir provenances in sub-Mediterranean Slovenia
Luka Krajnc, Jožica Gričar, Jernej Jevšenak, Polona Hafner, Robert Brus, 2022, izvirni znanstveni članek

Povzetek: Tree rings, wood density and the climate–growth relationship of four Douglas-fir provenances were analysed separately for the juvenile and adult phases. Four provenances were selected from an existing IUFRO provenance trial planted in 1971 based on their diameter at breast height and vitality. Increment cores were extracted from individual trees, on which we measured tree-ring widths (RW), earlywood widths (EWW) and latewood widths (LWW). Wood density was assessed in standing trees using resistance drilling. The climate–growth correlations were calculated between provenance chronologies of RW, EWW, LWW and latewood share, and the day-wise aggregated Standardised Precipitation-Evapotranspiration Index (SPEI). The analysis was done separately for the juvenile and mature phases of growth. Provenances 1064 (Jefferson) and 1080 (Yelm) exhibited larger annual radial increments than provenances 1028 (Merrit) and 1089 (Cathlamet). The two provenances with the highest annual radial increment in the juvenile phase did not exhibit the same trend in the adult phase. In all provenances, RW, and consequently EWW and LWW, were wider in the juvenile than in adult phase. The share of latewood was in all cases higher in juvenile wood than in mature wood. All four provenances had similar wood densities in both analyzed growth phases. Our analysis showed that when selecting the most promising provenance for planting, possible changes in relative growth rate from the juvenile to adult phase need to be considered.
Ključne besede: Pseudotsuga menziesii, SPEI, juvenile phase, adult phase, latewood share, resistance drilling
Objavljeno v DiRROS: 21.11.2022; Ogledov: 33; Prenosov: 12
.pdf Celotno besedilo (3,07 MB)
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8-oxoguanine forms quartets with a large central cavity
Simon Aleksič, Janez Plavec, Peter Podbevšek, 2022, izvirni znanstveni članek

Objavljeno v DiRROS: 21.11.2022; Ogledov: 32; Prenosov: 19
.pdf Celotno besedilo (3,94 MB)
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Controlled growth of ZnO nanoparticles using ethanolic root extract of Japanese knotweed : photocatalytic and antimicrobial properties
Miha Ravbar, Ajda Kunčič, Lev Matoh, Sonja Smole Možina, Martin Šala, Andraž Šuligoj, 2022, izvirni znanstveni članek

Povzetek: Synthesis of zinc oxide (ZnO) nanoparticles (NPs) was mediated by plant extracts to assist in the reduction of zinc atoms during the synthesis and act as a capping agent during annealing.The preparation used ethanolic extracts from the roots of Japanese knotweed (Fallopia japonica). Two major outcomes could be made. (i)A synergistic effect of multiple polyphenolic components in the extract is needed to achieve the capping effect of crystallite growth during thermal annealing at 450 °C characterized by an exponential growth factor (n) of 4.4 compared to n = 3 for bare ZnO. (ii) Synergism between the ZnO NPs and plant extracts resulted in superior antimicrobial activity against both Gram-positive bacteria, e.g., Staphylococcus aureus, and Gram-negative bacteria, e.g., Escherichia coli and Campylobacter jejuni. The materials were also tested for their antimicrobial activity against S. aureus under ultraviolet (UV) illumination. Also here, the photocatalyst prepared with plant extracts was found to be superior. The residues of the plant extract molecules on the surface of the catalyst were identified as the main cause of the observed differences, as proved by thermal gravimetry. Such a preparation using ethanolic extract of Fallopia japonica could serve as a more controlled synthesis of ZnO and potentially other metal oxides, with low environmental impact and high abundance in nature.
Objavljeno v DiRROS: 21.11.2022; Ogledov: 43; Prenosov: 20
.pdf Celotno besedilo (1,75 MB)
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Positional motif analysis reveals the extent of specificity of protein-RNA interactions observed by CLIP
Klara Kuret, Aram-Gustav Amalietti, D. Marc Jones, Charlotte Capitanchik, Jernej Ule, 2022, izvirni znanstveni članek

Objavljeno v DiRROS: 21.11.2022; Ogledov: 39; Prenosov: 18
.pdf Celotno besedilo (14,06 MB)
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