Tomas Bata University in Zlín
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Investigating the flexural properties of 3D-printed nylon CF12 with respect to the correlation between loading and layering directions
Full text linkThe article deals with the investigation of the flexural properties of 3D-printed Nylon CF12 with regard to the correlation between the loading and layering directions. It also discusses the prospective consideration of a suitable combination of lightweight material, 3D-printing, and cellular structures for application in sports, such as the production of poles for pole vaulting. Full-volume samples (with and without orbital shell) and porous (Diamond, Primitive, and Gyroid) samples sizes of 20 × 20 × 250 mm were fabricated and subjected to experimental three-point bending tests. The force–displacement dependencies were plotted, and the data were further evaluated. The results showed that the flexural properties of 3D-printed full-volume beams are significantly influenced by the direction of loading relative to the layering, while for porous beams with cellular structures, the differences in properties are very small. Also, the mismatches between the material properties listed in the datasheets and achieved within the research were identified and indicate the necessity to verify mechanical properties of newly developed products experimentally.Ministry of Education, Science, Research and Sport; Ministry of Education, Science, Research and Sports, (APVV-19-0550); Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA, (042TUKE-4/2025, M-HU-1506-2425); Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGAMinistry of Education, Science, Research and Sport of the Slovak Republic; [APVV-19-0550]; [KEGA 042TUKE-4/2025
Cryptocurrency in Vietnam: A deep dive into adoption factors and their interactions
Full text linkWhile traditional behavioral finance theories such as the TRA, TPB, and TAM have provided substantial insights, their application to the rapidly evolving digital finance sector, particularly cryptocurrency markets, has been limited. Addressing this gap, our study integrates Digital Trust Theory (DTT) with these frameworks to examine the role of government support in Crypto Adoption (CA) within Vietnam's dynamic but unregulated market, a prominent emerging market in global crypto trading. Utilizing Structural Equation Modeling, we processed data collected from 255 participants using SmartPLS 4.0 to explore complex relationships among User Characteristics (UC), Technology Characteristics (TC), External Environment (EX), and their impacts on Crypto Trust (CT) and Crypto Adoption CA. This dataset, comprising responses from a diverse array of participants including tech-savvy youths, business professionals, and financial experts across various regions of Vietnam, provides a robust basis for understanding the nuanced influences on cryptocurrency behaviors. Our findings underscore the significant mediating roles of Crypto Trust and governmental regulation, highlighting the crucial influence of External Environment factors on trust dynamics. These insights not only contribute to academic discourse by refining traditional behavioral finance theories for the digital era but also offer practical guidance for fostering a sustainable cryptocurrency market, thereby supporting economic development and financial security in Vietnam.Faculty of Management and Economics, Tomas Bata University in Zlín; Univerzita Tomáše Bati ve Zlíně, UTB; FaME TBU, (IGA/FaME/2024/015
Unlocking the potential of chlorophyll-based carbon dots towards water-splitting, white-light LED and encryption applications
No full textThe versatile traits of carbon dots (CD) have positioned them as a compelling subject of study across various burgeoning fields. This work has successfully sourced CD from a porphyrin-containing compound, chlorophyll, which boasts outstanding light-harvesting and energy transfer capabilities. CD with excellent physicochemical properties were synthesized using a low-cost solvothermal method. The optical properties of CD have been harnessed for water-splitting applications with ZnO, resulting in significantly improved current efficiency of the photoanodes. When irradiated with AM1.5 G illumination, ZnO/CD heterojunction provided the highest photocurrent efficiency (0.225 mA/cm2 at 1.23 V vs RHE) as a result of enhanced light absorption across the UV to the visible region and improved interfacial charge transfer kinetics in comparison to the pristine ZnO. Additionally, the nanocomposite prepared of CD and boric acid (BACD) evinced promising naked eye phosphorescence for 10 s with an average phosphorescence lifetime of 1.5 s. The BACD nanocomposite was used as a free-standing thin film phosphor material for white light LED preparation and as an ink for data encryption. The results demonstrate that the acquired CD hold substantial promise for a variety of applications.Intelligence & Talent for the Zlín Region; Changzhou Institute of Technology, CIT; Ministry of Education, Youth and Sports of the Czech Republic DKRVO, (RP/CPS/2024-28/007)Ministry of Education, Youth and Sports of the Czech Republic DKRVO [RP/CPS/2024-28/007
Electrical properties of semiconductor/conductor composites: Polypyrrole-coated tungsten microparticles
Full text linkTungsten microparticles were coated with globular or nanotubular polypyrrole in situ during the oxidation of pyrrole in aqueous medium with ammonium peroxydisulfate or iron(III) chloride, respectively. The resulting core–shell composites with various contents of tungsten were obtained as powders composed of metal particles embedded in a semiconducting polymer matrix. The coating of tungsten with polypyrrole was analysed by FTIR and Raman spectroscopies. The resistivity of composite powders was determined by the four-point van der Pauw method as a function of pressure applied up to 10 MPa. The degree of compression was also recorded and its relation to electrical properties is discussed on the basis of the percolation concept. The electrical properties of composites are afforded by polypyrrole matrix and they are independent of tungsten content. As the conducting tungsten particles are separated by polypyrrole shells, they cannot produce conducting pathways and behave similarly as a nonconducting filler.Ministry of Education, Youth and Sports of the Czech Republic; Technology Agency of the Czech Republic [TK03030157]; [DKRVO RP/CPS/2024-28/005]Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; DKRVO, (RP/CPS/2024-28/005); Technology Agency of the Czech Republic, TACR, (TK03030157); Technology Agency of the Czech Republic, TAC
How has climate change been affected by electricity digitalization, supply chain digitalization, and green technologies? Building a path to environmentally sustainable development in E7 nations
No full textConsumption-based CO2 emissions act as a critical indicator to identify the influence of electricity digitalization, supply chain digitalization, and green technologies on climate change, highlighting the need to establish appropriate environmental policies. This study addresses a significant gap in the literature by examining the relationship among electricity digitalization, supply chain digitalization, energy intensity, environment-related technologies, globalization, and economic growth on consumption-based CO2 emissions in the E7 nations from 1995 to 2023. Based on the Method of Moment Quantile Regression (MMQR), Bootstrap Quantile Regression (BSQR), and pairwise Dimitrescu causality tests, this study provides new findings on the drivers of CO2 emissions in these countries. The findings of the MMQR reveal that electricity digitalization, supply chain digitalization, energy intensity, and economic growth enhance CO2 emissions. Conversely, the results demonstrate that developing environment-related technology and globalization decreases CO2 emissions. It implies that even though digitalization, energy intensity, and economic growth may lead to emission intensification, there is evidence that it should reduce emission intensification through technological advancement, embracing green technologies and focusing intensely on environmental sustainability. Additionally, BSQR produced results similar to those of MMQR. The efficiencies highlighted in this study serve as important signals for policymakers. They must consider digitalization and economic growth while also promoting environmentally friendly practices. This aligns with SDG 13 (Climate Action), which aims to mitigate CO₂ emissions, and SDG 7 (Affordable and Clean Energy), which encourages energy efficiency and the transition to renewable energy sources in the E7 nations.National Natural Science Foundation of China, NSFC, (72174021); National Natural Science Foundation of China, NSFCNational Natural Science Foundation of China [72174021
Facile transformation of graphite composites into their porous analogues with superior electrical, thermal, and EMI shielding properties
No full textNovel porous conducting polymer composites were prepared through the direct expansion of expandable graphite within a melted polypropylene matrix. A facile in-situ method resulted in a remarkable reduction in the electrical percolation threshold of composites containing expanded graphite, forming an accordion-like network inside the polymer matrix compared to their non-expanded compact analogues. Despite their porosity, the expanded samples showed increased thermal conductivity, and the variation of electrical and thermal conductivity with the filler concentration adhered to the percolation theory and Lichtenecker model, respectively. Depending on the concentration, the expansion process notably enhanced the electromagnetic interference (EMI) shielding efficiency, producing a composite with shielding performance above 20 dB. The presented strategy enables a facile and cost-effective improvement of the electrical, thermal, and EMI shielding properties without affecting the weight of the composite, making it highly relevant for industrial adoption.Authors EK and TP acknowledge the project DKRVO (RP/CPS/2024-28/003), and RM and MC acknowledge DKRVO (RP/CPS/2024-28/007), supported by the Ministry of Education, Youth and Sports of the Czech Republic .Ministry of Education, Youth and Sports of the Czech Republic [RP/CPS/2024-28/003, RP/CPS/2024-28/007
Photoreforming of PET and PLA microplastics for sustainable hydrogen production using TiO2and g-C3N4photocatalysts
Full text linkPhotoreforming of polyethylene terephthalate (PET) and polylactic acid (PLA) microplastics has been investigated as a sustainable approach for hydrogen evolution. Thermodynamic analysis confirmed the feasibility of hydrogen evolution during the degradation of PET and PLA under UV irradiation (254anm). Photolysis experiments in water demonstrated that hydrogen, methane, and carbon monoxide were the primary gaseous products. PLA yields higher amounts of hydrogen than PET. The presence of NaOH significantly reduced hydrogen evolution, likely because of the scavenging of hydrogen radicals with hydroxide ions and neutralisation of carboxylic groups. Photocatalytic experiments in water using TiO2 and graphitic carbon nitride (g-C3N4) further increased the hydrogen yields of PET and PLA, with a more pronounced effect on PLA. However, in NaOH suspensions, hydrogen evolution increased only for PLA in the presence of TiO2, while g-C3N4 had no effect. This was attributed to the instability of g-C3N4 under alkaline conditions, as confirmed by the structural analysis.European Commission, EC, (CZ.10.03.01/ 00/22_003/0000048, CZ.02.01.01/00/23_021/0008588); European Commission, EC; Ministry of Education, Youth, and Sports, (LM2023056); Vysoká Škola Bánská - Technická Univerzita Ostrava, (SP 2024/009); Vysoká Škola Bánská - Technická Univerzita OstravaEuropean Union under the REFRESH - Research Excellence For REgion Sustainability and High-tech Industries [CZ.10.03.01/00/22_003/0000048, INOVO!!!, CZ.02.01.01/00/23_021/0008588]; Ministry of Education, Youth, and Sports - European Union [LM2023056]; VSB-Technical University of Ostrava [2024/009
Tribological characteristics of magnetorheological fluids based on carbonyl iron particles coated with various types of organosilanes
Full text linkMagnetorheological fluids (MRFs) belong to the category of smart materials capable of reversibly altering their rheological behaviour under the influence of an external magnetic field. One of the most critical issues encountered in real-world applications, such as semi-active damping systems, is the long-term operational stability caused primarily by the excessive wear of the contact surfaces of the system. This study investigates the tribological and rheological behavior of magnetorheological fluids (MRFs) containing carbonyl iron particles (CIPs) coated with various organosilanes. The MRFs were prepared using CIPs coated with (3-aminopropyl) triethoxysilane (APTES), tetraethoxysilane (TEOS), vinyltrimethoxysilane (VTMS), and hexamethyldisilane (HMDS). Tribological experiments, conducted using a ball-on-disc configuration, demonstrated that organosilane-coated CIPs significantly improve the tribological characteristics compared to bare CIPs. The specific wear rate decreased from 3.393 x 10-4 mm3 N-1 m-1 for bare CIPs to 1.248 x 10-4 mm3 N-1 m-1 for HMDS-coated CIPs. The friction coefficient was also reduced, with HMDS-coated CIPs showing the lowest value. Rheological experiments revealed a direct correlation between shear viscosity and magnetic field strength, with organosilane-coated CIPs exhibiting lower viscosity and improved sedimentation stability. Among the coatings, HMDS showed the most significant reduction in wear and friction, attributed to the formation of a protective tribo-layer.TBU in Zlin [IGA/FT/2025/004, FSI-S-23-8212, RP/CPS/2024-28/003, RP/CPS/2024-28/007
The significance of possible non-occlusive mesenteric ischemia in relation to neurological outcomes in patients with refractory cardiac arrest – Secondary analysis of the Prague OHCA study
No full textBackground: Intestinal injury as a consequence of ischemia–reperfusion injury after refractory cardiac arrest is not fully understood. This study evaluates the occurrence of clinical signs reflecting possible non-occlusive mesenteric ischemia (NOMI) to outcomes in patients with refractory cardiac arrest.
Methods: In a post-hoc analysis of a randomized, prospective Prague OHCA study comparing ECPR vs. CPR approaches in refractory out-of-hospital CA, all patients who survived longer than one hour after hospital admission were analyzed. We assessed possible NOMI based on clinical signs (mainly profuse diarrhea and abdominal distension) and their onset within 12 h of admission. Its occurrence was correlated with neurologically unfavorable outcome (Cerebral Performance Category (CPC) Scale 3–5) at 180 days. Cox regression was used to evaluate the relationship of particular variables to adverse neurological outcomes.
Results: Of the 256 study participants, 61 developed possible NOMI: 46 (51.7%) in the ECPR group and 15 (16.5%) in the CPR group. Adverse neurological outcomes occurred in 41 (89%) and nine (60%) patients, respectively. The number of patients developing possible NOMI was higher in those treated with ECPR (p > 0.01). Its occurrence correlated with cardiac arrest length, elevated levels of neuron-specific enolase and procalcitonin at 48 and 72 h. It was independently associated with adverse outcomes. In Cox regression, possible NOMI was associated with poor neurological outcomes in ECPR patients.
Conclusion: The development of profuse diarrhea, abdominal distension and other signs suggesting non-occlusive mesenteric ischemia in patients with refractory out-of-hospital cardiac arrest are observed more frequently in patients with poor neurological outcome at day 180, especially in patients treated with ECPR.Všeobecná Fakultní Nemocnice v Praze, VFN; Frank Lloyd Wright's Martin House, MH, (CZ-DRO-VFN64165); Frank Lloyd Wright's Martin House, MHVFN: General University Hospital in Prague [MH CZ-DRO-VFN64165]; Charles Universit
Influence of hydrolysis on non-isothermal crystallization of poly(butylene succinate-co-adipate) (PBSA)
Full text linkThis study investigates the impact of hydrolysis on the crystallization behavior of poly(butylene succinate-co-adipate) (PBSA), a biodegradable polyester. Hydrolysis was conducted in a controlled environment using phosphate-buffered saline at 70 °C to isolate the impact of hydrolytic degradation on the polymer’s properties. The consequent changes in molecular weight characteristics were tracked using gel permeation chromatography (GPC), revealing a decrease in both weight average molecular weight (Mw) and an increase in polydispersity index (PDI) as hydrolysis progressed. The thermal behavior of PBSA during hydrolysis was thoroughly investigated using differential scanning calorimetry (DSC), which demonstrated significant changes in melting temperature (Tm), glass transition temperature (Tg), and crystallinity (X). These changes in Tm and Tg suggest a change in copolymer composition, likely due to the greater susceptibility of the adipic acid unit to hydrolysis compared to the succinic acid unit. Furthermore, polarized optical microscopy (POM) was employed to observe the morphological evolution of PBSA, showing a transition from spherulitic structures in the early stages of hydrolysis to dendritic structures with prolonged hydrolysis time. The decrease in nucleation activity led to a reduction in the number of spherulites, which in turn allowed the remaining spherulites to grow larger.Department of Polymer Engineering, Faculty of Technology; Tomas Bata University in Zlín, TBU, (IGA/FT/2024/008); Tomas Bata University in Zlín, TBUDepartment of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlin; [IGA/FT/2024/008