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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: 385; Downloads: 244
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Keywords: kakovost lesa, perspektivne drevesne vrste, Quercus cerris, cer, Robinia pseudoacacia, navadna robinija, Populus sp., topol, Pinus nigra, črni bor, Pseudotsuga menziesii, navadna ameriška duglazija, Castanea sativa, pravi kostanj
Published in DiRROS: 27.03.2023; Views: 573; Downloads: 128
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Published in DiRROS: 14.03.2023; Views: 573; Downloads: 104
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Abstract: This paper is a study of the self-immolation of the Mahayana Buddhist monk Thich Quang Duc in 1963, Saigon. It highlights some of the reactions to this event, as well as more recent academic analyses, and contrasts them with the letter of the monk Thich Nhat Hanh who disagreed that the self-immolation was a protest or suicide. This ontological discrepancy motivated new research approaches. In order to show it as studyable, the paper thematizes it by introducing the conceptual pair of visible-invisible. It presents a discussion by Mario Blaser that addresses the field of epistemology and ontology, also commenting on some fundamental theoretical approaches such as the ontological turn and cosmopolitics. The paper argues that the invisible – for example ontological – contents of the event have been overlooked in many analyses, or oversimplified by using an objectivist or political vocabulary.
Keywords: Chinese religion, Buddhism, engaged Buddhism, politics, cosmopolitics, ontological turn, Western-centrism
Published in DiRROS: 28.02.2023; Views: 356; Downloads: 171
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Keywords: onkologija, rak dojke, kemoterapija
Published in DiRROS: 14.02.2023; Views: 387; Downloads: 95
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