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- ItemFUNCTIONAL TUNGSTEN-BASED THIN FILMS AND THEIR CHARACTERIZATION(TANGER Ltd, 2024-01-08) Košelová, Zuzana; Horáková, Lenka; Sobola, Dinara; Burda, Daniel; Knápek, Alexandr; Fohlerová, ZdenkaAnodization is a technique that can be used to create thin layers of oxide on the surface. Thin oxide layers have been found to be useful in a variety of applications, including emitters of electrons. Tungsten is still often choice for cold field emitters in commercial microscopy applications. His suitable quality can be improved even more by deposition of thin layer. Not only emission characteristic can be improved, but also emitter operating time can be prolonged. Tungsten oxide is known for its excellent resistance to corrosion and chemical attack, which is due to its stable crystal structure and the strong chemical bonds between tungsten and oxygen atoms. Many techniques were applied for this purpose, with various advantages and disadvantages. For this work anodization was chosen because of controllable uniform material coverage and easy accessibility without the need for expensive complex equipment. The anodization process involves applying an electrical potential to tungsten while it is immersed in an electrolyte solution. This causes a thin layer of tungsten oxide to form on the surface of the metal. The thickness and properties of the resulting oxide layer can be controlled by adjusting the anodization conditions, such as the electrolyte solution, voltage, and the duration of the process. In this work, H3PO4 was used as electrolyte To test whether these tungsten oxide layers would be viable for electron emitters, for use in electron guns and other devices that require high-quality electron emitters, we put them through a series of tests. Properties were evaluated using appropriate techniques. In general, anodization of tungsten to create thin tungsten oxide layers is a promising technique for producing high-quality electron emitters.
- ItemAssessing Lettuce Exposure to a Multipharmaceutical Mixture under Hydroponic Conditions: Findings through LC-ESI-TQ Analysis and Ecotoxicological Assessments(AMER CHEMICAL SOC, 2024-11-28) Mravcová, Ludmila; Jašek, Vojtěch; Hamplová, Marie; Navrkalová, Jitka; Amrichová, Anna; Zlámalová Gargošová, Helena; Fučík, JanThe escalating global water scarcity demands innovative solutions, one of which is hydroponic vegetable cultivation systems that increasingly use reclaimed wastewater. Nevertheless, even treated wastewater may still harbor various emerging organic contaminants, including pharmaceuticals. This study aimed to comprehensively assess the impact of pharmaceuticals, focusing on bioconcentration factors (BCFs), translocation factors (TFs), pharmaceutical persistence in aqueous environment, ecotoxicological end points, and associated environmental and health risks. Lettuce (Lactuca sativa) was cultivated hydroponically throughout its entire growth cycle, exposed to seven distinct concentration levels of contaminants ranging from 0 to 500 mu gL-1 over a 35-day period. The findings revealed a diverse range of BCFs (2.3 to 880 Lkg(-1)) and TFs (0.019-1.48), suggesting a high potential of pharmaceutical uptake and translocation by L. sativa. The degradation of 20 pharmaceuticals within the water-lettuce system followed first-order degradation kinetics. Substantial ecotoxicological effects on L. sativa were observed, including increased mortality, alterations in root morphology and length, and changes in biomass weight (p < 0.05). Furthermore, the estimated daily intake of pharmaceuticals through L. sativa consumption suggested considerable health risks, even if lettuce would be one of the many vegetables consumed. It is hypothetical, as the values were calculated. Moreover, this study assessed the environmental risk associated with the emergence of antimicrobial resistance (AMR) in aquatic environments, revealing a significantly high risk of AMR emergence. In conclusion, these findings emphasize the multifaceted challenges posed by pharmaceutical contamination in aquatic environments and the necessity of proactive measures to mitigate associated risks to both environmental and human health.
- ItemEvaluating stress resilience of cyanobacteria through flow cytometry and fluorescent viability assessment(Sringer, 2024-11-06) Kroupová, Zuzana; Slaninová, Eva; Mrázová, Kateřina; Krzyžánek, Vladislav; Hrubanová, Kamila; Fritz, Ines; Obruča, StanislavCyanobacteria are prokaryotic organisms characterised by their complex structures and a wide range of pigments. With their ability to fix CO2, cyanobacteria are interesting for white biotechnology as cell factories to produce various high-value metabolites such as polyhydroxyalkanoates, pigments, or proteins. White biotechnology is the industrial production and processing of chemicals, materials, and energy using microorganisms. It is known that exposing cyanobacteria to low levels of stressors can induce the production of secondary metabolites. Understanding of this phenomenon, known as hormesis, can involve the strategic application of controlled stressors to enhance the production of specific metabolites. Consequently, precise measurement of cyanobacterial viability becomes crucial for process control. However, there is no established reliable and quick viability assay protocol for cyanobacteria since the task is challenging due to strong interferences of autofluorescence signals of intercellular pigments and fluorescent viability probes when flow cytometry is used. We performed the screening of selected fluorescent viability probes used frequently in bacteria viability assays. The results of our investigation demonstrated the efficacy and reliability of three widely utilised types of viability probes for the assessment of the viability of Synechocystis strains. The developed technique can be possibly utilised for the evaluation of the importance of polyhydroxyalkanoates for cyanobacterial cultures with respect to selected stressor-repeated freezing and thawing. The results indicated that the presence of polyhydroxyalkanoate granules in cyanobacterial cells could hypothetically contribute to the survival of repeated freezing and thawing.
- ItemEffect of stabilized organic amendments on biodegradability of poly-3-hydroxybutyrate, soil biological properties, and plant biomass(Springer, 2024-09-27) Brtnický, Martin; Holátko, Jiří; Hammerschmiedt, Tereza; Mustafa, Adnan; Kameníková, Eliška; Kintl, Antonín; Radziemska, Maja; Baltazár, Tivadar; Malíček, Ondřej; Kučerík, JiříPoly-3-hydroxybutyrate (P3HB) is a biodegradable polymer with a potential extensive use in agriculture. However, while P3HB biodegradation boosts microbial enzyme activity, it significantly reduces plant biomass due to nutrient competition. In this study, we test the hypothesis that these detrimental effects can be mitigated though the co-application of nutrient-rich organic amendments, such as compost and digestate. A pot experiment with lettuce (Lactuca sativa), grown in soil amended with P3HB lone or combined with either compost or digestate. Six variants were tested: Control, Compost, Compost + P3HB, Digestate, Digestate + P3HB, and P3HB alone. We evaluated degradation of the P3HB polymer, biological soil properties, and both the dry and fresh biomass of the lettuce. We observed that adding P3HB alone enhanced dehydrogenase and urease activities, as well as all types of respiration, except for L-arginine-induced respiration. However, it strongly and negatively affected the biomass of lettuce (both aboveground and root). The strong adverse effects of P3HB on plant growth were also observed when compost was co-applied, although this combination enhanced all enzyme activities except for suppressed beta-glucosidase. Conversely, co-applying digestate with P3HB alleviated the negative effect of P3HB on both the dry and fresh biomass together lettuce. Additionally, this combination increased the activity of several enzymes (dehydrogenase, arylsulfatase, N-acetyl-beta-D-glucosaminidase, urease), and enhanced all types of respiration, except for L-arginine-induced respiration. The use of biodegradable plastics in agriculture is on rise, but it may be compromised, because their biodegradation my negatively impact plant growth. The results showed that co-application of digestate is an effective solution to alleviate these effects, while co-application of compost failed. Generally, organic amendments seem to be an option to alleviate the negative effects of bioplastics biodegradation, and offers options how to handle the treatment of waste bioplastics or their residues, but further investigation is needed to understand the underlaying mechanisms involved.
- ItemTemperature effect on the kinetic profile of Ziegler-Natta catalyst in propene polymerization(SPringer Nature, 2024-09-10) Kolomazník, Vít; Cejpek, Igor; Skoumal, MiroslavPropene polymerization kinetic profiles with a diether-based Ziegler-Natta MgCl2-supported catalyst were investigated in a stainless-steel batch reactor. The initial 10 min period characterizes various temperature levels with a constant volume of liquid propene. The lowest temperature level corresponds to the usual prepolymerization temperature (10 degrees C), and the highest level corresponds to the usual main polymerization temperature (70 degrees C). The effects of the starting temperature levels were evaluated through polymerization kinetic patterns computed namely from the second polymerization period carried out at 70 degrees C for the next 90 min. Based on the heat transfer data, the kinetic profiles were fitted to suitable semi-empirical equations derived from fundamental kinetic approaches using the first and second orders of the catalyst active sites decay. Both approaches adequately describe the dependence of the initial activities and deceleration constants on the temperature during the initial period.