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Development of chitosan nanocomposite coatings for visible-light photocatalytic antiviral applications / Framställning av kitosan-nanokompositbeläggningar för fotokatalytiska antivirala applikationer i synligt ljusNeuman, Michael January 2023 (has links)
During the global pandemic of coronavirus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak, the world was desperately searching for simpler yet more effective solutions to stop the spread of coronavirus (COVID-19). Since no one was prepared for the fast spread of such a contagious virus, there was a shortage of proper protective solutions to stop the spread. Large quantities of alcohol-based disinfectant and hand sanitizers were used, but it led to global shortages. It is desired to have a water-based, easily applied, low-cost and long-lasting disinfectant that can prevent the spread of coronavirus on any surface, without the issue of skin allergies or skin-drying as often found while using alcohol. Inspired by nature, chitosan (CS), a natural biopolymer with well-known antimicrobial and film-forming properties, was tested in this study for the preparation of coatings spread onto various surfaces and the antiviral effect was evaluated. Zinc oxide (ZnO), a material generally recognized as safe (GRAS) by the US Food and Drug Administration (FDA), is a photocatalyst that was embedded in chitosan to enhance the antimicrobial and antiviral performance of the coatings. In order to apply water-based chitosan formulation on hydrophobic polypropylene (PP) surgical mask and polyethylene terephthalate (PET) surface, the plastics were treated with either oxygen plasma or corona plasma to improve the surface hydrophilicity. The corona plasma treatment decreased the water contact angle (WCA) of the surgical mask from approximately 125° to 101° and drastically reduced WCA of the PET film from approximately 100° to 29°. The PET film was coated with CS – ZnO nanocomposite, which contains 1% chitosan and 5 wt.% (w.r.t weight of chitosan) ZnO nanoparticles. The capability of photocatalytic degradation of CS – ZnO coating was demonstrated during the degradation of methylene blue dye molecules. Additionally, we evaluated the antiviral effect of the CS – ZnO nanocomposite coating on PET plastic films under typical room lighting conditions by measuring the inactivation of lentivirus. This approach utilizes the pseudotype system, which is a reliable tool to study under conventional biosafety conditions, particularly for certain pathogenic strains of coronaviruses (CoVs) which have a strong pathogenicity. / Under den globala coronapandemin, utbrottet av allvarligt akut respiratoriskt syndrom coronavirus 2 (SARS-CoV-2), sökte världen desperat efter enklare men ändå mer effektiva lösningar för att stoppa spridningen av coronaviruset (COVID-19). Eftersom ingen var förberedd på en så smittsam sjukdom uppstod en brist på lämpliga skyddsmetoder för att stoppa spridningen. Stora mängder alkoholbaserade desinfektionsmedel och handdesinfektionsmedel användes, vilket skapade en global brist. Det önskades en vattenbaserad, lättapplicerad, kostnadseffektiv och långvarig desinfektionsmedel som kunde förhindra spridningen av coronaviruset på vilken yta som helst, utan problem med allergiska reaktioner eller uttorkning av huden som ofta uppstår vid användning av alkohol. Med inspiration från naturen testades kitosan, en naturlig biopolymer med välkända antimikrobiella och film-formande egenskaper, för att göra beläggningar på olika ytor och testa deras antivirala effekt. Zinkoxid (ZnO), ett material som allmänt erkänns som säkert (GRAS) av US Food and Drug Administration (FDA), är en fotokatalysator och användes i kitosanbeläggningen för att förbättra den antimikrobiella och antivirala effekten. För att applicera den vattenbaserade kitosanformuleringen på hydrofoba ytor på en kirurgisk mask av polypropen (PP) och en plastfilm av polyetylentereftalat (PET), behandlades plasterna med antingen O2 eller corona plasma för att förbättra ytornas hydrofilicitet. Behandlingen av corona plasma minskade vattenkontaktvinkeln på den kirurgiska masken från cirka 125° till 101° och för PET-filmen från cirka 100° till 29°. PET-filmen belades med CS – ZnO nanokomposit, som innehåller 1% kitosan och 5 wt.% (med avseende på vikten av kitosan) ZnO nanopartiklar. Förmågan till fotokatalytisk nedbrytning av CS – ZnO-beläggningen demonstrerades genom att bryta ned metylenblå färgmolekyler. Dessutom utvärderades vi den antivirala effekten av CS – ZnO nanokompositbeläggningen på PET-filmer i normal rumsbelysning genom att mäta dess förmåga att inaktivera lentivirus. Denna metod använder pseudotypsystemet, vilket är ett tillförlitligt verktyg för att studera under konventionella biosäkerhetsförhållanden, särskilt för vissa patogena stammar av coronavirusen (CoVs) som har en hög patogenicitet.
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Vysílání v roušce - sonda do výroby zpravodajství České televize vprostřed koronavirové krize / Broadcasting with a Face Mask - Insight into Czech TV News Production in the middle of the Coronavirus CrisisŠenkýř, Jan January 2020 (has links)
The thesis documents circumstances of TV news production at the time when the government was taking unprecedented measures to prevent from spreading of a new type of coronavirus (SARS- CoV-2). The documentation is based on ten interviews with Czech Television reporters and anchormen together with both the analysis and interpretation of these interviews. The work is bringing the evidence of journalists from the most turbulent period. It makes efforts to contextualize how the journalists perceived the government interventions as well as enforced changes in the course of their work. The thesis reflects also the role of the journalists themselves and how they see it themselves. The majority of interviews were done during emergency rule. The final text is based on oral history method alongside with the reflection on contact points with journalism. It reflects also on a possibility whether the coronavirus crisis might move both mentioned professions forward.
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Harmonizace rodinných a pracovních rolí u pracovníků bez možnosti práce z domova během koronavirové krize / Harmonization of family and work roles for workers who do not have the option of working from home during the coronavirus crisisŠrámková, Nikola January 2021 (has links)
The thesis deals with the harmonization of family and work roles of workers without the possibility of working from home during the so-called first wave of the coronavirus crisis in 2020. The goal of this thesis is to describe the harmonization possibilities of family and the work roles in the Czech Republic. Another goal of this thesis is to find out what circumstances influenced the parents without the possibility of working from home to stay at work during the COVID-19 pandemic. Last but not least, the goal was set to map the harmonization of the family and of the work roles of the parents without the possibility of working from home during the COVID-19 pandemic in the Czech Republic. The theoretical basis of the thesis is the concept of family-work conflict in conjunction with the concept of work-life balance. These theoretical aspects were conceptualized with the issue of Covid-19, labor market conditions and the tools that make it easier to match the parental and the work roles in the Czech Republic. The research work works with primary and secondary data. The primary data was obtained through the semi-structured interviews with the affected individuals (the parents who take care of a child under the age of 10 and at the same time working in a position without the possibility of working from...
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