Tomas Bata University in Zlín
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Analysis of rheological behavior of elastomeric blends
No full textThis work deals with the study of rheological properties of two types of elastomeric blends. Rheological properties such as shear rate, shear stress and dynamic (shear) viscosity of two types of elastomeric blends with a different compositions were measured. The properties were determined by capillary and oscillating rheometer under laboratory conditions and also by using an extruder under operating conditions. The work was mainly focused on determining of the deviation of elastomeric blends from Newtonian fluid flow, which was determined on the basis of obtained graphical dependences of blends from measured rheological parameters using different types of rheometers and a wide range of shear rates. Since elastomeric blends are considered to be pseudoplastic fluids, the shear viscosity values showed a decreasing tendency with increasing shear rate. Blend 1 has better flow properties and thus processing properties because the deviation from the Newtonian flow is smaller and closer to the ideal fluid flow. Blend 2 contains a higher proportion of natural rubber, and thus shows higher stiffness and poorer processability.European Regional Development Fund, ERDF, (313011W442, ITMS2014, KEGA 003TnUAD-4/2022
In situ doping polyanions enables concentration-gradient Ni-rich cathodes for long-life lithium-ion batteries
No full textThe novel Ni-rich cathode materials with concentration-gradient structures have become a research hotspot by virtue of their advantages of high specific capacity and thermal stability. However, the unfavorable interdiffusion of transition metals (TMs) during lithiation leads to flattening of the gradient and weakens the surface passivation effect. Herein, we successfully constructed a concentration-gradient nickel-rich cathode with an average composition of LiNi0.83Co0.05Mn0.12O2 via a SiO44- polyanion doping strategy (GNCM-Si). SiO44- doping allows the preservation of the concentration-gradient structure at high lithiation temperatures by hindering TM (Ni, Mn) interdiffusion, ensuring high surface stability of nickel-rich cathodes at the end of charge. Besides, the strong Si-O bond effectively stabilizes the lattice oxygen framework, thereby reducing oxygen evolution and further enhancing thermal stability. Accordingly, the as-obtained concentration-gradient cathode demonstrates a high reversible specific capacity of 210.5 mA h g-1 and a high Coulombic efficiency of 89.7% at 0.1C. Impressively, it retains 92.7% of its initial capacity after 500 cycles in pouch-type full cells at 25 °C and 1C. This finding offers a viable idea for constructing concentration-gradient cathodes to meet the high safety requirements of lithium-ion batteries.National Natural Science Foundation of China, NSFC, (21975074, 91834301); Shanghai Municipal Education Commission; Fundamental Research Funds for the Central UniversitiesNational Natural Science Foundation of China [21975074, 91834301]; National Natural Science Foundation of China; Innovation Program of Shanghai Municipal Education Commission; Fundamental Research Funds for the Central Universitie
Effect of extraction methods on aroma profile, antioxidant activity and sensory acceptability of specialty coffee brews
Get PDFSpecialty coffees from various geographical origins were processed using different extraction methods. Four extraction techniques were employed: cold brew (CB), espresso (ES), French press (FR), and aeropress (AE). The potential health benefits of coffee brews were linked to their antioxidant activity, as determined by the DPPH assay, and total polyphenol content (TPC) measured through the Folin–Ciocalteu reducing-capacity assay. The Columbia (C) espresso coffee type (omni-roasting) exhibited the highest antioxidant activity (86.31 ± 0.70) μmol/100 mL, with a TPC value of (44.41 ± 0.35) mg GAE/g. Quantitative analyses of caffeine and chlorogenic acid were conducted using high-performance liquid chromatography (HPLC). The evaluation of coffee aroma profiles involved the application of headspace solid-phase microextraction/gas chromatography–mass spectrometry (HS-SPME/GC-MS) and was complemented by sensory analysis following the Specialty Coffee Association (SCA) standard protocol. The predominant volatile compounds found in all samples included furans, phenols, pyrazines, and terpenes. The EY espresso type (medium dark roasting) had the highest levels of most coffee volatiles. The C cold brew type (omni-roasting) was rated as the preferred coffee in terms of its sensory characteristics and flavour. In summary, ES and CB were found to be more effective extraction methods for the parameters assessed.Tomas Bata University in Zlín, TBU, (IGA/FT/2023/007); Univerzita Palackého v Olomouci, UP, (IGA_PRF_2023_024)Palacky University in Olomouc [IGA_PRF_2023_024]; Tomas Bata University in Zlin [IGA/FT/2023/007
Comparison of plasma-polymerized thin films deposited from 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline: I film properties
Get PDFPoly(2-oxazoline) is a promising new class of polymeric materials due to their antibiofouling properties and good biocompatibility. Poly(2-oxazoline) coatings can be deposited on different substrates via plasma polymerization, which can be more advantageous than other coating methods. The aim of this study is to deposit poly(2-oxazoline) coatings using a surface dielectric barrier discharge burning in nitrogen at atmospheric pressure using 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline vapours as monomers and compare the film properties. For the comparison, the antibacterial and cytocompatibility tests were peformed according to ISO norms. The antibacterial tests showed that all the deposited films were highly active against Staphylococcus aureus and Escherichia coli bacteria. The chemical composition of the films was studied using FTIR and XPS, and the film surface’s properties were studied using AFM and surface energy measurement. The cytocompatibility tests showed good cytocompatibility of all the deposited films. However, the films deposited from 2-methyl-2-oxazoline exhibit better cytocompatibility. This difference can be explained by the different chemical compositions and surface morphologies of the films deposited from different monomers.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (DKRVO RP/CPS/2022/005, RP/CPS/2022/001, RP/CPS/2022/002); Ministerstvo Obrany České Republiky, MOČRMinistry of Defence of the Czech Republi
Degradation of polylactic acid/polypropylene carbonate films in soil and phosphate buffer and their potential usefulness in agriculture and agrochemistry
Get PDFBlends of poly(lactic acid) (PLA) with poly(propylene carbonate) (PPC) are currently in the phase of intensive study due to their promising properties and environmentally friendly features. Intensive study and further commercialization of PPC-based polymers or their blends, as usual, will soon face the problem of their waste occurring in the environment, including soil. For this reason, it is worth comprehensively studying the degradation rate of these polymers over a long period of time in soil and, for comparison, in phosphate buffer to understand the difference in this process and evaluate the potential application of such materials toward agrochemical and agricultural purposes. The degradation rate of the samples was generally accompanied by weight loss and a decrease in molecular weight, which was facilitated by the presence of PPC. The incubation of the samples in the aqueous media yielded greater surface erosions compared to the degradation in soil, which was attributed to the leaching of the low molecular degradation species out of the foils. The phytotoxicity study confirmed the no toxic impact of the PPC on tested plants, indicating it as a “green” material, which is crucial information for further, more comprehensive study of this polymer toward any type of sustainable application.Uniwersytet Humanistyczno-Przyrodniczy im. Jana Długosza w Częstochowie, UJD; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Ministerstwo Edukacji i Nauki, MNiSWDKRVO; Ministry of Science and Higher Education for the Jan Dlugosz University in Czestochow
The effect of synthesis method and oxidizing agent on cytotoxicity and ecotoxicity of polyaniline
No full textThe unique properties of polyaniline (PANI), as representative of conducting polymers (CPs) predetermine their use in biomedical field. While the material properties of PANI prepared by chemical or microwave synthesis are well known, their biological properties have not been adequately addressed and compared. To fill this gap, PANI powders were prepared by either chemical or microwave synthesis using different oxidizing agent (ammonium persulfate, APS vs potassium iodate, KIO3) and studied. The effect on cytotoxicity and ecotoxicity were determined according to the ISO protocol and inhibition of bioluminescence in Photobacterium phosphoreum, respectively. The significant effect of both factors, the synthesis route and oxidizing agent, on biological performance was confirmed. The choice of optimum preparation condition for PANI synthesis highly improved its cytotoxicity and ecotoxicity compared to previously described PANI forms. Results of the here presented work are crucial for the further utilization of PANI in wide spectrum of biomedical applications.DKRVO, (RP/CPS/2022/001); TBU in Zlin, (IGA/CPS/2023/001); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GA ČR, (23-07425S); Ministry of Business, Innovation and Employment, MBIE, (UOAX0812); Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja, MPNTR, (451-03-47/2023-01/200146)Ministry of Education, Science and Technological Development of the Republic of Serbia [UOAX0812]; Ministry of Education, Youth and Sports of the Czech Republic [451-03-47/2023-01/200146]; TBU in Zlin [RP/CPS/2022/001]; Resources of Specific Academic Research [IGA/CPS/2023/001
Influence of personal cultural orientations in artificial intelligence adoption in small and medium-sized enterprises
No full textThis study aims to propose a theoretical model that examines the significance of personal cultural orientations, specifically focusing on innovativeness, independence, and ambiguity intolerance, in the adoption of artificial intelligence (AI) within small and medium-sized enterprises (SMEs). Additionally, the study establishes a relationship between personal cultural orientations and the Unified Theory of Acceptance and Use of Technology (UTAUT), particularly considering performance expectancy and facilitating conditions. SMEs face unique challenges and barriers in their pursuit of competitiveness, which necessitate alternative approaches and methodologies to foster the acceptance of new innovations like AI, beyond traditional technology adoption models. Employing a qualitative methodology, emphasizing documentary research, and utilizing inferential and deductive reasoning, a theoretical model is proposed. This model aims to demonstrate how analysing personal cultural orientations can facilitate the design of effective strategies and policies to support SMEs’ AI adoption, promoting their growth and sustainability in a technology-driven and highly volatile environment
Unveiling the mediating nexus of digital transformation on digital leadership and enterprise performance in manufacturing firms
No full textIn today's rapidly evolving business landscape, digital transformation has become an imperative for organizations seeking to stay competitive and relevant. The relentless advancement of technology has brought about unprecedented opportunities and challenges, necessitating a shift in leadership paradigms to embrace the digital era fully. This investigation seeks to test the nexus between digital leadership, digital transformation, and enterprise performance. Empirically, the Smart PLS approach was employed to test the affiliation between digital leadership and enterprise performance, through the mediating effect of digital transformation. We collected data on manufacturing firms consisting of 471 managers across the various regions of Ghana. The finding indicates that digital leadership and digital transformation exhibit a positive affiliation with enterprise performance. Finally, digital transformation had a favorable mediating effect on the nexus between digital leadership and enterprise performance. Practitioners and firms would be motivated to seize the advantages of digital transformation as an opportunity to improve firm performance. Again, manufacturing firms that want to be leaders in the digital space have to acquire the services of a digital leader as part of their management portfolio team. This study contributes to the literature by providing new theoretical explanations for the inconsistent affiliation between digital leadership, digital transformation, and enterprise performance. This investigation also assists enterprises in reevaluating their digital strategies
Mechanical resistance of safety elements in transportation
Get PDFPolycarbonate is a thermoplastic polymer used in many sectors including security and transportation. Polycarbonate plastic parts can be used in automotive applications because of their low strain, durability, performance, and slow deterioration. This engineering polymer is easily moldable, processable, and thermoformable. This article tests the polycarbonate shield, grit from the polycarbonate shield, and injection molded polycarbonate specimens on a drop-weight impact test. This study is focused on the comparison of the mechanical properties (especially on the impact resistance) between injection molded polycarbonate, and polycarbonate safety shield. Statistical evaluation of the results shows that the injection molded polycarbonate does not reach the mechanical properties of the protect shield.Internal Grant Agency of Tomas Bata University, (IGA/CebiaTech/2023/001
The impact of religiosity on quality of life
No full textBackground: The article explored certain aspects of Christianity and its impact on a person's quality of life, the relationship between Greek eudaimonia and New Testament Beatitudes, as well as the connection between quality of life and postmodern hedonism.
Conclusion: Further research could also focus on various groups of respondents who are not immediately threatened by illness or death and investigate how the impact of religiosity on quality of life, social capital, or health is perceived among them.[VEGA 1/0706/20]; [KEGA 011KU-4/2023