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72. Preliminary chemical and mineralogical characterization of tailings from base metal sulfide deposits in Serbia and North MacedoniaTimotheus 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: 551; Prenosov: 164
 Celotno besedilo (4,76 MB) |
73. Controlled growth of ZnO nanoparticles using ethanolic root extract of Japanese knotweed : photocatalytic and antimicrobial propertiesMiha 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: 438; Prenosov: 205
Celotno besedilo (1,75 MB)
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74. Characterization of atmospheric deposition as the only mineral matter input to ombrotrophic bogValentina Pezdir, Martin Gaberšek, Mateja Gosar, 2022, izvirni znanstveni članek Povzetek: Ombrotrophic peatlands contain a very small percentage of mineral matter that they receive exclusively from atmospheric deposition. Mineral matter deposited on the Šijec bog was characterized using scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). We collected solid atmospheric deposition from snow, rainwater, and using passive samplers. Samples were collected at average atmospheric conditions and after two dust events. Size, morphology, and chemical composition of individual particles were determined. We distinguished four main particle groups: silicates, carbonates, organic particles, and Fe-oxyhydroxides. Silicate particles are further divided into quartz and aluminosilicates. Proportions of these groups vary between samples and between sample types. In all samples, silicate particles predominate. Samples affected by dust events are richer in solid particles. This is well observed in passive deposition samples. Carbonates and organic particles represent smaller fractions and are probably of local origin. Iron-oxyhydroxides make up a smaller, but significant part of particles and are, according to their shape and chemical composition, of both geogenic and anthropogenic origin. Estimated quantity and percentage of main groups vary throughout the year and are highly dependent on weather conditions. Dust events represent periods of increased deposition and contribute significantly to mineral matter input to peatlands.
Ključne besede: atmospheric deposition, SEM/EDS, mineral matter, peatland
Objavljeno v DiRROS: 08.09.2022; Ogledov: 547; Prenosov: 258
Celotno besedilo (3,51 MB)
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75. The effect of dietary fibre content on skatole and indole production in faeces of immunocatrsted male pigsMaja Prevolnik, Urška Tomažin, Marjeta Čandek-Potokar, Martin Škrlep, Nina Batorek Lukač, Etienne Labussiere, 2015, objavljeni znanstveni prispevek na konferenci Ključne besede: prašiči, prehrana prašičev, vlaknine, imunokastracija
Objavljeno v DiRROS: 06.09.2022; Ogledov: 637; Prenosov: 233
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77. Carcass and meat quality traits of pig fatteners from Slovenian Breeding programmeMaja Prevolnik, Martin Škrlep, Dejan Škorjanc, Marjeta Čandek-Potokar, 2008, objavljeni znanstveni prispevek na konferenci Povzetek: The aim of the present study was the comparison of carcass and meat quality traits of commercial pigs of various crossbreeds from two major Slovenian herds. The analysis is based on phenotypic data from field trials which have been collected in the last past five years within the Slovenian breeding programme. Important differences in carcass traits were observed between two herds and were associated to different crossbreeds used. In spite of that economically important result on the slaughter line (lean meat %) was similar for both herds. Meat quality traits were also significantly different between the two herds. Again, the difference could be ascribed to crossbreeds used. However, since the herd effect is connected with abattoir effect, different ante-mortem conditions and/or lower robustness of these animals to premortal stress could also be contributed to the observed differences. The presented results give important information on the state-of-the-art regarding meat quality of Slovenian pigs.
Ključne besede: pigs, carcass quality, meat, breeding programs, Slovenia
Objavljeno v DiRROS: 06.09.2022; Ogledov: 656; Prenosov: 230
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78. Influence of housing conditions on reliability of immunocastration and consequences for growth performance of male pigsKevin Kress, Ulrike Weiler, Sonja Schmucker, Marjeta Čandek-Potokar, Milka Vrecl, Gregor Fazarinc, Martin Škrlep, Nina Batorek Lukač, Volker Stefanski, 2020, izvirni znanstveni članek Povzetek: Immunocastration is a sustainable alternative to piglet castration but faces limited market acceptance. The phenomenon of non-responders has not to date been examined in detail, but adverse and stressful housing conditions (e.g., mixing of groups) might impair the success of vaccinations. Therefore, we evaluated the influence of housing conditions on the immune response after two Improvac® vaccinations at an age of 12 and 22 weeks, respectively. Boars, immunocastrates and barrows (n = 48 each) were assigned to three different housing conditions (n = 36 enriched, n = 36 standard n = 72 repeated social mixing). Immune response was quantified by measuring GnRH-binding and its consequences for testosterone concentrations, development of the genital tract and boar taint. Growth performance was evaluated via average daily gain (ADG). GnRH-binding and testosterone levels revealed that immunocastration reliably suppressed testicular functions after the 2nd vaccination. Housing conditions did not modify testicular function but influenced ADG as animals under mixing grew slower than those under enriched conditions. Gonadal status had only a slight impact on ADG except in immunocastrates, which showed a temporarily higher ADG after the 2nd vaccination. The results show that immunocastration is a reliable procedure under different housing conditions and competitive in terms of growth performance.
Ključne besede: immunocastration, vaccination, Improvac, non-responder, immune response, housing conditions, surgical castration, boar taint, growth performance, genital tract
Objavljeno v DiRROS: 06.09.2022; Ogledov: 626; Prenosov: 226
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