51. Effects of desiccation and freezing on microbial ionizing radiation survivability : considerations for Mars sample returnWilliam H. Horne, Tine Grebenc, Rok Tkavc, Cene Gostinčar, Nina Gunde-Cimerman, 2022, izvirni znanstveni članek Povzetek: Increasingly, national space agencies are expanding their goals to include Mars exploration with sample return. To better protect Earth and its biosphere from potential extraterrestrial sources of contamination, as set forth in the Outer Space Treaty of 1967, international efforts to develop planetary protection measures strive to understand the danger of cross-contamination processes in Mars sample return missions. We aim to better understand the impact of the martian surface on microbial dormancy and survivability. Radiation resistance of microbes is a key parameter in considering survivability of microbes over geologic times on the frigid, arid surface of Mars that is bombarded by solar and galactic cosmic radiation. We tested the influence of desiccation and freezing on the ionizing radiation survival of six model microorganisms: vegetative cells of two bacteria (Deinococcus radiodurans, Escherichia coli) and a strain of budding yeast (Saccharomyces cerevisiae); and vegetative cells and endospores of three Bacillus bacteria (B. subtilis, B. megaterium, B. thuringiensis). Desiccation and freezing greatly increased radiation survival of vegetative polyploid microorganisms when applied separately, and when combined, desiccation and freezing increased radiation survival even more so. Thus, the radiation survival threshold of polyploid D. radiodurans cells can be extended from the already high value of 25 kGy in liquid culture to an astonishing 140 kGy when the cells are both desiccated and frozen. However, such synergistic radioprotective effects of desiccation and freezing were not observed in monogenomic or digenomic Bacillus cells and endospores, which are generally sterilized by 12 kGy. This difference is associated with a critical requirement for survivability under radiation, that is, repair of genome damage caused by radiation. Deinococcus radiodurans and S. cerevisiae accumulate similarly high levels of the Mn antioxidants that are required for extreme radiation resistance, as do endospores, though they greatly exceed spores in radioresistance because they contain multiple identical genome copies, which in D. radiodurans are joined by persistent Holliday junctions. We estimate ionizing radiation survival limits of polyploid DNA-based life-forms to be hundreds of millions of years of background radiation while buried in the martian subsurface. Our findings imply that forward contamination of Mars will essentially be permanent, and backward contamination is a possibility if life ever existed on Mars.
Ključne besede: ionizing radiation, life on Mars, astrobiology, radiation, fungi, bacteria, radiotolerance
Objavljeno v DiRROS: 03.11.2022; Ogledov: 683; Prenosov: 325
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52. Mid-Cretaceous calcarenite in stone products from the Roman colony of Emona, Regio X (modern Ljubljana, Slovenia)Rok Brajkovič, Bojan Djurić, David Gerčar, Blanka Cvetko Tešović, Boštjan Rožič, Luka Gale, 2022, izvirni znanstveni članek Povzetek: Over the course of studying stone products from theRoman colony of Emona (Regio X), stratigraphicallyundefined calcarenite that was used to make simplesepulchral and architectural stone products wasdetected. The calcarenite used is late Aptian to earlyCenomanian in age. The corresponding facies werefound in the Lower Flyschoid Formation outcroppingnear the town of Medvode, within the local radius ofEmona. The Roman quarry was likely located in thisarea near the Sava River. According to the collecteddata, the quarry was in operation mainly in the 1stcentury.
Ključne besede: Cretaceous, microfacies, quarry production, Regio X, Roman time, stone products
Objavljeno v DiRROS: 17.08.2022; Ogledov: 754; Prenosov: 489
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53. Multi-method study of the Roman quarry at Podpeč sedimentary succession and stone productsRok Brajkovič, Luka Gale, Bojan Djurić, 2022, izvirni znanstveni članek Povzetek: The paper presents a multi-method characterisation of the Roman quarry of the middle Lower Jurassic (Pliensbachian) limestone situated in the village of Podpeč, south of Ljubljana, and examples of the placement of stone products made from micritic, fine-grained, and oolithic facies into the known extent of the quarry. 23 m of the rock succession from the ancient quarry was exposed at the northern tip of the St. Ana Hill by archaeological trenching. Petrological, micropaleontological, mineralogical, geochemical, and isotopic analyses of carbon, oxygen, and strontium were performed in order to characterise the rocks exploited in the quarry. Additionally, a new detailed geological map of the wider Podpeč area was prepared, which defines in detail the lithostratigraphic units in the area.
Ključne besede: Lower Jurassic, Podbukovje Formation, provenance, facies, foraminifera, geochemistry, Emona, geoarchaeology
Objavljeno v DiRROS: 27.07.2022; Ogledov: 859; Prenosov: 291
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54. Kamnolom apnenca v Podpeči pri Ljubljani in njegovi izdelkiBojan Djurić, Luka Gale, Rok Brajkovič, 2022, izvirni znanstveni članek Povzetek: Kamnolom v naselju Podpeč pri Ljubljani velja za glavni kamnolom rimske kolonije Emone (Ljubljana). Obstoj antič-nega kamnoloma v Podpeči je bil do sedaj utemeljen le na podlagi makroskopske podobnosti med Členom litiotidnega apnenca, ki izdanja v Podpeči, in z njim povezanimi rimskimi spomeniki, odkritimi v Ljubljani. V okviru pričujočega dela smo skušali poiskati oprijemljive arheološke in geoarheološke dokaze za njegov obstoj. V skrajno severnem delu kamnoloma smo izvedli arheološko sondiranje, hkrati pa natančno določili sestavo apnenca na tem območju in v 288 izdelkih iz antične Emone. Sondiranje severno od modernega kamnoloma je odkrilo dobro ohranjene sledove rimsko-dobne kamnoseške dejavnosti. Hkrati je litološka analiza spomenikov iz Emone razkrila, da je kar 182 (ali 64 odstotkov) analiziranih spomenikov izdelanih iz apnenca, litološko identičnega različkom, ki izdanjajo v Podpeči. Ti različki se prostorsko grupirajo severno od modernega kamnoloma. Pri tem sicer ostaja odprto vprašanje pripadnosti nekaterih različkov apnenca v izdelkih, ki so brez diagnostičnih komponent in bi lahko pripadali tudi nekoliko starejšemu Členu krkinega apnenca. Rekonstrukcijo obsega starega kamnoloma omogoča primerjava faciesov izvornih litostratigrafskih enot in izdelkov, pa tudi historična analiza zgodnjih kartografskih in katastrskih dokumentov. Analiza najzgodnejših izdelkov je omogočila hipotezo o prihodu kamnosekov iz kamnoloma v Nabrežini.
Ključne besede: Slovenija, Podpeč, Emona, rimska doba, litiotidni apnenec, mikrofaciesna analiza, rimski in novoveški kamnolom, izdelki
Objavljeno v DiRROS: 21.07.2022; Ogledov: 831; Prenosov: 616
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56. Nacionalna gozdna inventura : interna navodila za terensko delo (2020-2024) : (ver. 02 / 2022) : dopolnitve 13. 5. 2022Mitja Skudnik, Jure Žlogar, Aleš Poljanec, Rok Pisek, Anže Martin Pintar, Gal Kušar, Matjaž Guček, Andrej Grah, Marko Kovač, 2020, slovar, enciklopedija, leksikon, priročnik, atlas, zemljevid Ključne besede: nacionalna gozdna inventura, monitoring, terenske meritve, trajne vzorčne ploskve, navodila
Objavljeno v DiRROS: 07.06.2022; Ogledov: 995; Prenosov: 404
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57. Influence of deep cryogenic treatment on natural and artificial aging of Al-Mg-Si alloy EN AW 6026Matic Klug Jovičević, Rok Rezar, Patricia Jovičević Klug, Bojan Podgornik, 2022, izvirni znanstveni članek Ključne besede: aluminum alloy, microstructure, mechanical properties, precipitation, dispersoids, deep cryogenic treatment
Objavljeno v DiRROS: 06.05.2022; Ogledov: 651; Prenosov: 248
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58. Priporočila za obravnavo bolnikov z rakom debelega črevesa in danke2020, slovar, enciklopedija, leksikon, priročnik, atlas, zemljevid Ključne besede: rak debelega črevesa, rak danke, bolniki, zdravljenje
Objavljeno v DiRROS: 18.03.2022; Ogledov: 937; Prenosov: 518
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59. Furfural hydrogenation over Cu, Ni, Pd, Pt, Re, Rh and Ru catalysts : Ab initio modelling of adsorption, desorption and reaction micro-kineticsRok Šivec, Matej Huš, Blaž Likozar, Miha Grilc, 2022, izvirni znanstveni članek Objavljeno v DiRROS: 08.03.2022; Ogledov: 660; Prenosov: 523
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60. Potential link between ectomycorrhizal community composition and host tree phenologyTina Unuk Nahberger, Rok Damjanić, Hojka Kraigher, Tine Grebenc, 2021, izvirni znanstveni članek Povzetek: The timing of leaf phenology tends to be crucial in controlling ecosystem processes such as the acquisition of carbon and water loss as well as in controlling tree nutrient cycling. To date, tree phenology has mostly been associated with environmental control (e.g., temperature and photoperiod) in a relationship with inheritance, while it has rarely been linked with ectomycorrhizal community compositional changes through the host tree’s phenological stages. Seasonal variations of fungal communities have been widely studied, but little is known about mycorrhiza community composition changes along phenological stages. Therefore, we analyzed ectomycorrhizal communities associated with silver fir and their compositional changes during the transition between phenological stages. The phenological stages of each individual tree and time of bud break were monitored weekly for two years and, at the same time, ectomycorrhiza was harvested from selected silver fir trees. In total, 60 soil cores were analyzed for differences in the ectomycorrhizal community between phenological stages using Sanger sequencing of individual ectomycorrhizal morphotypes. A significant difference in beta diversity for an overall ectomycorrhizal community was confirmed between analyzed time periods for both sampled years. Species-specific reactions to transitions between phenological stages were confirmed for 18 different ectomycorrhizal taxa, where a positive correlation of Russula ochroleuca, Russula illota, Tomentella sublilacina, and Tylospora fibrillosa was observed with the phenological stage of bud burst.
Ključne besede: Abies alba (Mill.), ectomycorrhizal community, phenological stages
Objavljeno v DiRROS: 20.12.2021; Ogledov: 870; Prenosov: 637
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