Tomas Bata University in Zlín
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Application of green solvents as a replacement of toxic dimethylformamide in the polylactic acid electrospinning process
No full textNanofibres based on polylactic acid (PLA) have a wide range of applications, including air filtration. They are prepared by electrospinning using toxic solvents as dimethylformamide. This study focused on the use of green solvents to prepare electrospinnable solutions. It was found that a combination of solvents is necessary. A nozzle electrospinning technique was applied to produce PLA nanofibres from optimised dual (ethyl or methyl lactate with acetone) or ternary (cyclopentanone, acetone and ethyl or methyl lactate) solvent system. The prepared nanofibres were evaluated for morphology and quality of nanofibres (SEM), surface wettability (contact angle), filtration properties (automated filter tester) and pore size and distribution (porometry). Potential changes in the chemical composition and the presence of residual solvent were investigated by FTIR, TGA and headspace analysis. It was found that green solvents can substitute dimethylformamide; especially combination of cyclopentanone/ethyl lactate/acetone provides air filtration properties comparable to dimethylformamide/acetone-based systems.European Just Transition Fund; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Ministerstvo Životního Prostředí, MŽP, (CZ.10.03.01/00/22_003/0000045, CZ.02.01.01/00/23_021/0009004); Ministerstvo Životního Prostředí, MŽP; Tomas Bata University in Zlín, TBU, (RP/CPS/2024-28/002); Tomas Bata University in Zlín, TBUEuropean Just Transition Fund within the Operational Programme: Just Transition under the aegis of the Ministry of the Environment of the Czech Republic [CZ.10.03.01/00/22_003/0000045]; European Just Transition Fund within the Operational Programme Johannes Amos Comenius OP JAC "Application potential development in the field of polymer materials in the context of circular economy compliance (POCEK) " [CZ.02.01.01/00/23_021/0009004]; Development process of Centre of Polymer Systems, Tomas Bata University in Zlin, program DKRVO - Ministry of Education Youth and Sports of the Czech Republic [RP/CPS/2024-28/002
Design and surface enhancement of ABS parts manufactured by Arburg plastic freeforming (APF) using chemical vapor treatment
Get PDFAdditive manufacturing (AM) has become a key technology for fabricating highly customized products without the need for specific tools. Despite the benefits, this technology has some limitations, such as a poor surface finish of the products. Chemical treatment methods have been proven effective for the enhancement of surface finish. To this date, such treatments were applied to the objects manufactured by various AM methods, but there is no data available for the products manufactured by Arburg plastic freeforming (APF). The APF is a unique technique based on the deposition of tiny polymer droplets to build a final component directly from pellets. In this study, we investigate the effects of chemical treatment in hot acetone vapors on the surface roughness, (micro)mechanical properties, and optical and molecular changes of acrylonitrile butadiene styrene (ABS) samples produced by APF. The dynamics of the treatment process were studied as a function of exposure time to acetone vapors. The results showed that bulk mechanical properties were preserved, while significant changes occurred in the surface mechanics, specifically the indentation hardness. Along with the chemical treatment, the surface roughness exhibited nontrivial behavior but ultimately yielded a ∼ 90 % reduction after 35 s, texture homogenization with the simultaneous improvement in gloss, from 2.2 to 45 GU, and surface aesthetics. The surface finishing process was very fast and easily scalable, offering valuable information for the design of ABS products in industrial applications.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMTMinistry of Education, Youth and Sports of the Czech Republic [RP/CPS/2024-28/007
Cycling towards sustainable tourism and mobility: Insights from the Czech Republic
No full textThe purpose of this article is to explore the role of cycling tourism in promoting sustainable urban mobility and environmentally friendly tourism practices, with a focus on the Czech Republic. The study investigates the motivations, behaviors, and preferences of cycling tourists, particularly in the post-COVID-19 context. Findings reveal that relaxation and exploring new destinations are primary motivations for cyclists, who favor dedicated cycling paths over mixed road traffic. Generation Z tends to use bicycles for leisure activities with friends, rather than for long-distance touring. Contrary to expectations, the availability of charging stations for e-bikes is not yet a significant factor influencing cycling route choices in the country. The results also show that, during long-distance cycling trips, tourists tend to prefer local guesthouses or alternative forms of accommodation over hotels. Cyclists also prioritize routes that are close to amenities such as dining facilities, highlighting the importance of accessible infrastructure. Furthermore, after the pandemic, there has been a shift towards active forms of mobility, such as walking and cycling, over the use of public transport. This study provides valuable insights into how cycling tourism can contribute to sustainability goals by promoting eco-friendly travel options and encouraging urban planners to develop cycling-friendly infrastructure. The findings suggest that cycling tourism is an important driver of sustainable urban mobility, offering a model for integrating tourism with broader urban development strategies focused on reducing environmental impacts.Tomas Bata University in Zlín, TBU, (IGA/FaME/2023/015); Tomas Bata University in Zlín, TB
Factors influencing internationalization of micro-enterprises and SMEs in Central Europe
Get PDFInternationalizing a company is particularly challenging for microenterprises and SMEs due to the limited resources available for managing strategic activities. This paper aimed to create a model of the factors influencing the internationalization process of micro-enterprises and SMEs from Central Europe. The study employed principal component analysis to identify latent components of the model, namely innovation, strategic management (SM), and barriers. The factors and their relationships were analyzed using Logit regression and ANOVA. Additionally, the influence of two control variables on the selected factors and barriers to internationalization was examined. The research findings indicate that the most significant barrier to internationalization is the difference in tax policies. Furthermore, a significant correlation exists between innovation and strategic management barriers, while the strategies for innovation depend on the size and age of the company.Debreceni Egyetem, D
A comprehensive review of natural fiber reinforced Polymer composites as emerging materials for sustainable applications
No full textThe increasing depletion of fossil fuels and the growing demand for eco-friendly materials have driven the development of natural fiber composites. These composites possess desirable mechanical properties such as eco-friendliness, good thermal characteristics, lightweight, lower production costs, and renewability, making them preferable to synthetic composites made from glass and carbon. The use of natural fiber composites in various industries such as automotive, construction, defense, and infrastructure has grown due to their ability to reduce greenhouse gas emissions. This review examines recent advancements in natural fiber reinforced Polymer composites (NFRPCs), focusing on the diverse types of natural fibers such as flax, hemp, and ramie used as fillers and various plastics employed as Polymer matrices. It also discusses the pre-processing treatments of natural fibers, including chemical, mechanical, and thermal methods, which are crucial for optimizing NFRPC properties. Additionally, the review discusses both conventional and advanced manufacturing techniques and the key factors influencing the production quality of NFRPCs and their diverse industrial applications. However, a major challenge for NFRPCs is the hydrophilic nature of plant fibers, which limits bonding with the Polymer matrix and results in poor mechanical characteristics. Future research should focus on developing effective and affordable surface modifiers, dispersion aids, or coupling agents and on understanding the bonding mechanisms at the interface. Nanoscale interfacial characterization is crucial for exploring stress transfer, interfacial penetration, and adhesion. Incorporating nano reinforcements such as graphene and carbon nanotubes can enhance interfacial properties but preserving the intrinsic strength of modified fibers remains a challenge. Eco-friendly in-situ Polymer coatings such as polydopamine and polypyrrole offer potential solutions.Univerzita Tomáše Bati ve Zlíně, UTB, (IGA/FT/2025/004); Univerzita Tomáše Bati ve Zlíně, UTB; TAČR TREND, (FW10010536)Tomas Bata University, Zlin, Czech Republic [IGA/FT/2025/004]; TACR TREND [FW10010536
Unlocking the role of byproducts in reactive laser ablation in liquids: A pathway to dual-function Au-Ti nanostructures
No full textIn this study, we explore the dual functionality of reactive laser ablation in liquids (RLAL) for fabricating nonequilibrium Au-Ti nanoparticles (NPs) and laser-induced periodic surface structures (LIPSS) on Ti solid targets. By irradiating Ti solid targets in an aqueous KAuCl4 solution, we synthesize Au-Ti NPs with distinct optoelectronic properties, including enhanced light absorption into the visible spectrum and plasmonic effects that promote efficient charge separation. Concurrently, LIPSS formed on the Ti surface act as heterogeneous nucleation sites, facilitating controlled nanostructure growth and significantly enhancing the solid target's photocatalytic performance. Both the NPs and treated Ti solid target exhibit promising electrochemical activity, with the presence of Au-boosting light-driven processes under UV and visible light. The synergy between the NPs’ optoelectronic behavior and the potential catalytic properties of the modified Ti surfaces creates a versatile platform for applications in photocatalysis, energy conversion, and sensors after further developments. Our findings underscore RLAL as a sustainable, efficient method for creating multielement nanostructures and modifying solid surfaces, advancing their utility in green chemistry and light-driven technologies.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (RP/CPS/2024-28/007)European Union [101079345]; Ministry of Education, Youth and Sports of the Czech Republic [RP/CPS/2024-28/007
Detecting and Preventing Credential Misuse in OTP-Based Two and Half Factor Authentication Toward Centralized Services Utilizing Blockchain-Based Identity Management
No full textThis paper focuses on the problem of detection and prevention of stolen and misused secrets (such as private keys) for authentication toward centralized services. We propose a solution for this problem, based on SmartOTPs, the two-factor authentication scheme against the blockchain, which is intended for smart contract wallets and utilizes one-time passwords (OTPs). We modify SmartOTPs for our purposes and utilize them in the setting of two-and-a-half-factor authentication against a centralized service provider. Out of two and a half factors of our solution, the first factor stands for the private key, and the second and a half factor stands for OTPs and their precursors (a.k.a., pre-images), where OTPs are obtained from the precursors by cryptoaraphically secure hashing. We describe the protocol for bootstrapping our approach as well as the authentication procedure. In the case of stolen creden-tials from the client, we show that our solution enables the user to immediately detect it and proceed to re-initialization with fresh credentials. We utilize blockchain-based identity management and decentralized identities of users to simplify the overhead of the registration process and reinitialization.Key Digital Technologies Joint Undertaking, KDT JU, (101007273, FIT-S-23-8151); Key Digital Technologies Joint Undertaking, KDT J
Integration of gold nanoparticles into BiVO4/WO3 photoanodes via electrochromic activation of WO3 for enhanced photoelectrochemical water splitting
Get PDFThe development of highly efficient photoanodes is crucial for enhancing the energy conversion efficiency in photoelectrochemical water splitting. Herein, we report an innovative approach to fabricating an Au/BiVO4/WO3 ternary junction that leverages the unique benefits of WO3 for efficient electron transport, BiVO4 for broadband light absorption, and Au nanoparticles (NPs) for surface plasmon effects. The BiVO4/WO3 binary junction was constructed by depositing a BiVO4 layer onto the surface of the WO3 nanobricks via consecutive drop casting. Au NPs were subsequently integrated into the BiVO4/WO3 structure through electrochromic activation of WO3. The optimal BiVO4 loading for the highest-performing BiVO4/WO3 heterostructure and the light intensity dependence of the photocurrent efficiency were also determined. Flat-band potential measurements confirmed an appropriate band alignment that facilitates electron transfer from BiVO4 to WO3, while work function measurements corroborated the formation of a Schottky barrier between the incorporated Au NPs and BiVO4/WO3, improving charge separation. The best-performing Au NP-sensitized BiVO4/WO3 photoanode thin films exhibited a photocurrent density of 0.578 mA cm-2 at 1.23 V vs RHE under AM 1.5G (1 sun) illumination and a maximum applied-bias photoconversion efficiency of 0.036% at 1.09 V vs RHE, representing an enhancement factor of 12 and 2.3 compared to those of pristine BiVO4 and WO3 photoanodes, respectively. This study presents a promising and scalable route for fabricating noble metal-sensitized, metal oxide-based nanocomposite photoanodes for solar water splitting.Ministry of Education, Youth and Sports of the Czech Republic DKRVO, (RP/CPS/2024-28/007); INTER-EXCELLENCE, (LTT20010); Horizon 2020, (739566, 101122061); Horizon 2020Horizon 2020 Framework Programme [RP/CPS/2024-28/007, LTT20010]; Ministry of Education, Youth and Sports of the Czech Republic DKRVO [739566, 101122061]; European Union's Horizon 2020 research and innovation programme [CIT-ZK]; Intelligence & Talent for the Zlin Regio
Covalently conjugated polypyrrole-chitosan nanofibrous conductive composites prepared using dialdehyde polysaccharide linkers
No full textPolypyrrole (PPy) composites, despite their conductivity and bioactivity, are prone to degradation (e.g., exfoliation or delamination) due to the lack of chemical bonds between PPy and the matrix. Rather than suppressing this degradation through laborious methods involving toxic organic linkers or custom pyrrole derivatives to achieve covalently bonded PPy composites, this study introduces a novel polysaccharide-based approach. This method uses dialdehyde polysaccharides (DAPs) to conjugate PPy to chitosan nanofibers (CHITs) covalently. DAPs stabilize CHITs through Schiff base chemistry and then conjugate pyrrole via aldol condensation. During subsequent polymerization, the conjugated pyrrole is incorporated into the PPy layer formed around the CHITs, covalently linking both polymers. The resulting composites exhibit good conductivity and cytocompatibility, making them promising for biomedical applications and tissue engineering. Moreover, this method is not limited to chitosan but can be extended to other amine-containing substrates.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GAČR, (24- 11534S); Grantová Agentura České Republiky, GAČR; Centre of Polymer Systems, (RP/CPS/2024-28/001
Superior microwave absorbing cement-based composite using graphite flake / MnFe2O4 spinel ferrite nanoparticles
No full textIn this study, graphite flake-cement (GFC) composite and MnFe2O4-cement (MFC) nanocomposite with desirable porous structures were developed. The microwave absorption performance of developed cement composites was investigated in the X-band frequency (8.2–12.4 GHz). The developed GFC composite displayed a minimum reflection loss of −19.3 dB (corresponding to 98.826 % electromagnetic wave absorption) at 9.7 GHz with a thickness of 7 mm and an effective absorption bandwidth (EAB) (at which the reflection loss reaches −10 dB) of 0.8 GHz. The MFC composite attained the minimum reflection loss of −44.5 dB (corresponding to 99.996 % EM wave absorption) at 11.7 GHz with a thickness of 7 mm and EAB of 1.3 GHz. The study suggests that adding conductive graphite flakes or MnFe2O4 spinel ferrite magnetic fillers into cement can provide efficient microwave absorption characteristics. The electromagnetic parameters, such as complex permittivity and permeability, dielectric loss, and magnetic loss, were also analyzed. In addition, the results of this study implied that the graphite flakes or MnFe2O4 nanoparticle-incorporated cement composite might be used to create buildings with greater resistance to electromagnetic radiation.Tomas Bata University in Zlín, TBU; Centre of Polymer Systems; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; DKRVO, (RP/CPS/2024-28/007); Internal Grant Agency, (IGA/CPS/2025/004)Ministry of Education, Youth and Sports of the Czech Republic - DKRVO at the Centre of Polymer Systems [RP/CPS/2024-28/007]; Tomas Bata University in Zlin, Czech Republic; Internal Grant Agency [IGA/CPS/2025/004