61. Environmental hazard of polypropylene microplastics from disposable medical masks : acute toxicity towards Daphnia magna and current knowledge on other polypropylene microplasticsAnita Jemec Kokalj, Andraž Dolar, Damjana Drobne, Marjan Marinšek, Matej Dolenec, Luka Škrlep, Gregor Strmljan, Branka Mušič, Andrijana Sever Škapin, 2022, original scientific article Abstract: The COVID-19 pandemic has increased the use of disposable plastics, including medical masks, which have become a necessity in our daily lives. As these are often improperly disposed of, they represent an important potential source of microplastics in the environment. We prepared microplastics from polypropylene medical masks and characterised their size, shape, organic chemical leaching, and acute toxicity to the planktonic crustacean Daphnia magna. The three layers of the masks were separately milled and characterised. Each of the inner frontal, middle filtering, and outer layers yielded different types of microplastics: fibres were obtained from the inner and outer layer, but irregular fragments from the middle layer. The shape of the obtained microplastics differed from the initial fibrous structure of the intact medical mask layers, which indicates that the material is deformed during cryo-milling. The chemical compositions of plastics-associated chemicals also varied between the different layers. Typically, the inner layer contained more chemicals related to antimicrobial function and flavouring. The other two layers also contained antioxidants and their degradation products, plasticisers, cross-linking agents, antistatic agents, lubricants, and non-ionic surfactants. An acute study with D. magna showed that these microplastics do not cause immobility but do physically interact with the daphnids. Further long-term studies with these microplastics are needed using a suite of test organisms. Indeed, studies with other polypropylene microplastics have shown numerous adverse effects on other organisms at concentrations that have already been reported in the environment. Further efforts should be made to investigate the environmental hazards of polypropylene microplastics from medical masks and how to handle this new source of environmental burden.
Keywords: COVID-19 pandemic, plastics-associated chemicals, Daphnia magna, fibres, fragments, nanofibres, polypropylene microplastics, single-use plastic
Published in DiRROS: 05.05.2023; Views: 413; Downloads: 260
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62. Analyte-driven clustering of bio-conjugated magnetic nanoparticlesTilen Potisk, Jurij Sablić, Daniel Svenšek, Elena Sanz-de Diego, Francisco J. Teran, Matej Praprotnik, 2023, original scientific article Keywords: biochemistry, nanoparticles, magnetic nanoparticles, proteins, biosensors
Published in DiRROS: 16.03.2023; Views: 594; Downloads: 235
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66. Lower Permian (Artinskian) chondrichthyan tooth remains (Petalodontidae) from Dovje (Karavanke Mts., NW Slovenia)Matija Križnar, 2022, original scientific article Abstract: Fossil remains of chondrichthyan tooth bases (roots) were found in Lower Permian beds exposed along the forest road between Dovje and Plavški Rovt. These layers are part of the clastic development of the Trogkofel Group beds. They are composed of an alternation of dark to light-grey shales, siltstone, and sandstone with rare beds of the conglomerate. Within the clastic succession, layers or lenses of dark-grey to black limestones (biosparitic, biomicritic and oolitic) and limestone breccias occur. The limestone consists remains of algae, fusulinids, brachiopods, and mostly crinoids (Palermocrinus and Entrochus). Detail study has shown that two remains of tooth bases belong to the genus Petalodus, one of them to the species Petalodus ohioensis. The bases are tongue-shaped and come to a rounded point in the distal (base end) edge. On the surface of the base, the typical oval-shaped foramina are visible. In addition, the osteodentine is visible on the cross-section of one specimen. Teeth of Petalodus are often the most common chondrichthyan fossil vertebrate remains reported from the Carboniferous and Permian rocks of the USA, Europe, and Russia. In Slovenia, Petalodus ohioensishas been recorded only from Upper Carboniferous beds. The new record of Lower Permian remains contributes to the knowledge of this cosmopolitan but still common genus of Late Paleozoic chondrichthyans.
Keywords: fossils, Petalodontiformes, Petalodus ohioensis, Upper Paleozoic, Artinskian, Karavanke Mountains, Slovenia
Published in DiRROS: 18.01.2023; Views: 667; Downloads: 295
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68. Vloga javne gozdarske službe pri obvladovanju požara Goriški Kras in posledice požara za gozdne ekosistemeAleš Poljanec, Boris Rantaša, Jaša Saražin, Branka Gasparič, Matej Kravanja, Marija Kolšek, Boštjan Košiček, 2022, professional article Abstract: Požar Goriški Kras, ki je vzplamtel 15. 7. 2022, pogašen pa je bil 29. 7. 2022, je doslej največji požar v Sloveniji, saj je zajel skupaj 3.707 ha površin, od tega 2.902 ha gozdov. Pogorela površina v Sloveniji in Italiji skupaj obsega okoli 4.500 ha. V intervencijo gašenja požara je bila že prvi dan nastanka požara vključena javna gozdarska služba, ki jo opravlja Zavod za gozdove Slovenije. Gozdarji so štabu za vodenje intervencije dali na voljo gozdarske karte z zarisom vseh prometnic. Zaradi dobrega poznavanja terena je bila glavna naloga ZGS sprva pomagati posameznim gasilnim enotam pri orientaciji v prostoru in usmerjanju po protipožarnih presekah in gozdnih cestah. V času največjega razvoja požara so bile naloge delavcev ZGS preusmerjene v sečnjo ob prometnicah in naseljih, kjer bi bilo mogoče ustaviti širjenje požara. V aktivnost so se vključili tudi gozdarji družbe Slovenski državni gozdovi (SiDG) in iz ZGS vpoklicani izvajalci sečnje in drugih del na protipožarnih presekah ter prostovoljci. Neposredna škoda v gozdovih je bila ocenjena na 24,9 milijona evrov, požar pa je pomembno prizadel tudi ekološke in socialne funkcije gozda
Keywords: požari v naravnem okolju, Goriški Kras, javna gozdarska služba, intervencijski posek, protipožarno varstvo
Published in DiRROS: 13.12.2022; Views: 631; Downloads: 176
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69. Comparison of the corrosion properties of CoCrMo dental alloys in artificial salivaTadeja Kosec, Mirjam Bajt Leban, Matej Kurnik, Igor Kopač, 2021, original scientific article Abstract: CoCrMo alloys are known for their biocompatible properties, which, together with their favorable mechanical properties, mean they can be efficiently used in dentistry. With the development of selective laser melting for the fabrication of 3D-printed ob - jects, interest in the corrosion properties of this alloy has risen in the field of prosthodontics. In the study, CoCrMoW dental al - loys were studied in artificial saliva at body temperature, i.e., 37 °C. Different forms of CoCrMoW alloy were selected: a refer - ence sample, i.e., original material as received from the supplier, a cast sample acquired from an ordinary procedure in a dental laboratory, and two 3D-printed samples made from CoCrMoW powder using the selective laser melting (SLM) method. Electro - chemical, spectroscopic and hardness measurements were conducted. It was shown that the reference and cast samples have similar microstructural and electrochemical properties, while the electrochemical properties of the 3D-printed samples differ, most probably due to the effect of the higher micro porosity and chemical composition of the alloys.
Keywords: CoCrMo dentalne zlitine, umetna slina, aditivne tehnologije, precizijsko ulivanje, korozija
Published in DiRROS: 02.12.2022; Views: 345; Downloads: 135
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