Tomas Bata University in Zlín
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Titanium dioxide and halloysite loaded polylactic acid-based membrane continuous flow photoreactor for 17α-ethinylestradiol (EE2) hormone degradation: Optimization, kinetics, mechanism, and reusability study
No full textExposure to endocrine-disrupting chemicals (EDCs) has been linked to harmful effects in biota due to their widespread chemical persistence. In this paper, we report on the fabrication of electrospun polylactic acid (PLA) based nanofibers functionalized with TiO2 nanoparticles. The PLA-based TiO2 nanofibers were further stabilized with the incorporation of halloysite (HNT) particles. The nanofibers were fabricated in varied concentrations of HNT (5, 10, 15%), while TiO2 was kept at 10% for all the prepared samples. The fabricated samples were evaluated for elimination of synthetic 17α-ethinylestradiol (EE2) hormone as a model EDC pollutant. By using combined adsorptive and photocatalytic processes, the as-prepared samples were evaluated in a continuous flow system under dark and UV-light irradiation for EE2 removal. The best-performing sample with an optimized concentration of PLA/TiO2/HNT (85, 10, 5%) was able to eliminate 71.6% of EE2 hormone under UV irradiation at a hormone concentration of 0.1 mg/L. The maximum removal capacity obtained was 1.26 mg/g in 2 h, which best fitted the pseudo-first-order kinetics model. The sample was further utilized for additional experiments by changing experimental parameters, such as contact time, solution pH, and flow rate. To elucidate the actual degradation of the EE2 hormone, LCMS analysis was carried out to monitor the formation of by-products, which indicated that EE2 was fragmented into different potentially benign molecules. Finally, the best-performing sample was utilized for ten cyclic runs under optimized conditions for which the sample maintained sufficiently high degradation without any loss in structural integrity. Overall, the results showed that the developed PLA/TiO2/HNT nanofibers have a high potential to target persistent organic pollutants.DKRVO, (RP/CPS/2022/002, RP/CPS/2022/007); Ministry of Education , Youth, and Sports of the Czech Republic; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Fundação para a Ciência e a Tecnologia, FCT, (2022.06165, LA/P/0056/2020, UIDP/00100/2020); Universitat de Barcelona, UBMinistry of Education, Youth, and Sports of the Czech Republic-DKRVO [RP/CPS/2022/002, RP/CPS/2022/007]; Fundacao para a Ciencia e Tecnologia [2022.06165. PTDC, PIDDAC-UIDB/00100/2020, UIDP/00100/2020, LA/P/0056/2020
Pressure-driven piezoelectric sensors and energy harvesting in biaxially oriented polyethylene terephthalate film
Get PDFThis study reports the possibility of using biaxially oriented polyethylene terephthalate (BOPET) plastic packaging to convert mechanical energy into electrical energy. Electricity is generated due to the piezoelectricity of BOPET. Electricity generation depends on the mechanical deformation of the processing aids (inorganic crystals), which were found and identified by SEM and EDAX analyses as SiO2. BOPET, as an electron source, was assembled and tested as an energy conversion and self-powered mechanical stimuli sensor using potential applications in wearable electronics. When a pressure pulse after pendulum impact with a maximum stress of 926 kPa and an impact velocity of 2.1 m/s was applied, a voltage of 60 V was generated with short-circuit current and charge densities of 15 μAcm−2 and 138 nCm−2, respectively. Due to the orientation and stress-induced crystallization of polymer chains, BOPET films acquire very good mechanical properties, which are not lost during their primary usage as packaging materials and are beneficial for the durability of the sensors. The signals detected using BOPET sensors derived from pendulum impact and sieve analyses were also harvested for up to 80 cycles and up to 40 s with short-circuit voltages of 107 V and 95 V, respectively. In addition to their low price, the advantage of sensors made from BOPET plastic packaging waste lies in their chemical resistance and stability under exposure to oxygen, ultraviolet light, and moisture.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (RP/CPS/2022/003, RP/CPS/2022/007)Ministry of Education, Youth, and Sports of the Czech Republic [RP/CPS/2022/007, RP/CPS/2022/003
Iron-nickel metal foams modified by phosphides as robust catalysts for a hydrogen evolution reaction
No full textMinisterstvo školstva, vedy, výskumu a športu Slovenskej republiky, (VEGA 1/0095/21, VEGA 2/0027/23); Agentúra na Podporu Výskumu a Vývoja, APVV, (APVV-20-0299, APVV-20-0576)Scientific Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic [VEGA 1/0095/21, VEGA 2/0027/23]; Slovak Research and Development Agency [APVV-20-0299, APVV-20-0576
Mechanical properties and Mullins effect in rubber reinforced by montmorillonite
Get PDFThe present work investigated the properties of rubber vulcanizates containing different nanoparticles (Cloisite 20A and Cloisite Na+) and prepared using different sonication amplitudes. The results showed that a maximum improvement in tensile strength of more than 60% over the reference sample was obtained by the nanocomposites containing 2 wt.% Cloisite 20A and 1 wt.% Cloisite Na+ and mixed with a maximum amplitude of 270 μm. The modulus at 300% elongation increased by approximately 18% and 25% with the addition of 2 wt.% Cloisite 20A and 3 wt.% Cloisite Na+, respectively. The shape retention coefficient of rubber samples was not significantly affected by the mixing amplitude, while the values of the softness measured at the highest amplitude (270 μm) were higher compared to those of mixtures homogenized with lower amplitudes. The loading-unloading and loading-reloading processes showed similar trends for all tested nanocomposites. However, they increased with increasing levels of sample stretching but were not significantly affected by filler content at a given elongation. More energy was dissipated during the loading-unloading process than during the loading-reloading. SEM micrographs of rubber samples before and after cycling loading showed rough, stratified, and elongated morphologies. XRD results showed that elastomeric chains were intercalated in the MMT nanosheets, confirming the improvement of mechanical properties. The difference between the hydrophilic pristine nanoclay (Cloisite Na+) and organomodified MMT (Cloisite 20A) was also highlighted, while the peaks of the stretched rubber samples were smaller, regardless of the rubber composition, due most probably to the decrease of interlayer spacing
Nutritional and bioactive properties and antioxidant potential of Amaranthus tricolor, A. lividus, A viridis, and A. spinosus leafy vegetables
Get PDFClimate change results in continuous warming of the planet, threatening sustainable crop production around the world. Amaranth is an abiotic stress-tolerant, climate-resilient, C4 leafy orphan vegetable that has grown rapidly with great divergence and potential usage. The C4 photosynthesis allows amaranth to be grown as a sustainable future food crop across the world. Most amaranth species grow as weeds in many parts of the world, however, a few amaranth species can be also found in cultivated form. Weed species can be used as a folk medicine to relieve pain or reduce fever thanks to their antipyretic and analgesic properties. In this study, nutritional value, bioactive pigments, bioactive compounds content, and radical scavenging potential (RSP) of four weedy and cultivated (WC) amaranth species were evaluated. The highest dry matter, carbohydrate content, ash, content of iron, copper, sodium, boron, molybdenum, zinc, β-carotene and carotenoids, vitamin C, total polyphenols (TP), RSP (DPPH), and RSP (ABTS+) was determined in Amaranthus viridis (AV). On the other hand, A. spinosus (AS) was found to have the highest content of protein, fat, dietary fiber, manganese, molybdenum, and total flavonoids (TF). In A. tricolor (AT) species the highest total chlorophyll, chlorophyll a and b, betaxanthin, betacyanin, and betalain content was determined. A. lividus (AL) was evaluated as the highest source of energy. AV and AT accessions are underutilized but promising vegetables due to their bioactive phytochemicals and antioxidants.Department of Genetics and Plant Breeding; King Saud University Riyadh Saudi Arabia; Bangabandhu Sheikh Mujibur Rahman Agricultural University, BSMRAU, (RSP2024R346); Internal Grant Agency of Tomas Bata University in Zlín, (IGA/FT/2024/006)Department of Genetics and Plant Breeding, the Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh; King Saud University Riyadh Saudi Arabia [IGA/FT/2024/006]; Internal Grant Agency of Tomas Bata University in Zlin; [RSP2024R346
The impact of digital platforms on the creativity of remote workers through the mediating role of explicit and tacit knowledge sharing
No full textPurpose: Remote working has brought forward many challenges for employees as the phenomenon is still new for most employees across the globe. Some of these challenges may be addressed by the recent adoption of digital technologies by organizations. In this vein, our study explores the impact of digital platform capability on the creativity of employees through the mediating mechanism of explicit and tacit knowledge sharing.
Design/methodology/approach: The data were gathered from higher education institutes (HEIs) in a developing country, Pakistan which recently saw a major disruption during the Covid-19 pandemic. The proposed hypotheses were tested through Structural Equational Modeling (SEM) and the results confirmed our hypotheses.
Findings: The findings confirmed that the digital platform capabilities impact both tacit and explicit knowledge sharing among these remote employees. Likewise, the results also supported the mediating role of both explicit and tacit knowledge sharing on the creativity of these remote workers.
Originality/value: Our results are significant as they confirm the impact of digitalization on remote workers’ creativity predisposition. We thus advance the academic debate on the problems of knowledge sharing in remote working. We prove that digital capabilities outweigh the challenges created due to new forms of work driven by the pandemic. It further highlights the important areas to focus on while planning human resource policies in the new normal
Experimental study on the distribution and growth characteristics of trapped air bubbles in ice slices at different freezing temperatures
No full textIcing is a phenomenon that exists widely in daily life and industry, and always brings some disadvantages. The dissolved air tends to become micro bubbles and trapped in ice, which have an effect on the physical properties of the ice. To explore the distribution and growth characteristics of trapped air bubbles in ice, experiments are carried out in a horizontal Hele-Shaw cell at different freezing temperatures. Results show that the trapped air bubbles in ice are classified into egg-shaped bubbles and needle-shaped bubbles according to an aspect ratio of bubble length to width larger and smaller than five. All the widths, lengths, and volumes of egg-shaped and needle-shaped bubbles increase with the distance from the cooler increasing and the freezing temperature decreasing. The length and volume of needle-shaped bubbles are larger than those of egg-shaped ones. The behaviors of trapped air bubbles are mainly affected by the freezing rate. When the bubble growth rate is greater than 20 μm/s, there are only egg-shaped bubbles in the ice, and when the bubble growth rate is less than 10 μm/s, there are only needle-shaped bubbles in the ice. The volumes of ESBs and NSBs both increase linearly with the bubble growth time at all freezing temperatures. These findings help deepen the understanding of trapped air bubbles in ice and provide guidance for improving icing and optimizing deicing strategies.National Foreign Expert Project, (G2022178023L); National Natural Science Foundation of China, NSFC, (52076013); Ministry of Science, ICT and Future Planning, MSIP; National Research Foundation of Korea, NRF, (51925605); Beijing Municipal Science and Technology Commission, Adminitrative Commission of Zhongguancun Science Park, (3212024)National Natural Science Foundation of China [52076013, 51925605]; Beijing Municipal Science & Technology Commission [3212024]; Government of the Republic of Korea (Ministry of Science and ICT); National Research Foundation of Korea; National Foreign Expert Project [G2022178023L
Incremental clickstream pattern mining with search boundaries
No full textRecently, there has been a growing interest in sequential pattern mining in data mining, with a particular focus on clickstream pattern mining. These areas hold the potential for discovering valuable patterns. However, traditional mining algorithms in these domains often assume that databases are static, simplifying the mining process. In reality, databases are updated incrementally over time, partially rendering a portion of the previous results invalid. This necessitates rerunning algorithms on updated databases to obtain accurate frequent patterns. As database size increases, this approach can become time-consuming and affect performance. To tackle this issue, we propose PSB-CUP to mine frequent clickstream patterns in an incremental update manner. PSB-CUP employs the concept of search borders to reduce the search space and the information retained in memory. Furthermore, an IDList generation method called “partial imbalance join” was proposed to reconstruct possibly missing information during the incremental process. This join method, however, requires more extra information to be cached in exchange for speed. We then improve this technique by introducing “recursive imbalance join”, removing the need for extra cached data in the PSB-CUP + algorithm. The experimental results show that our proposed algorithms are efficient for incremental clickstream pattern mining.Faculty of Applied Informatics, Tomas Bata University in Zlin; Internal Grant Agency of Tomas Bata University, (IGA/CebiaTech/2023/004)Internal Grant Agency of Tomas Bata University [IGA/CebiaTech/2023/004
A modern pathway to the prevention of cardiovascular diseases
No full textIntroduction: Nutrition is an essential lifestyle factor for maintaining good health. The correct composition of food is an essential part of the prevention of cardiovascular diseases. Proper nutrition is a basic prerequisite for healthy human development and the main condition for the prevention of cardiovascular diseases. Therefore, in our research, we focused on the modern prevention of cardiovascular diseases.Research sample group and research objective: We approached 240 cardiology clinic patients who came for a checkup cardiology examination with various cardiology diagnoses. The goal of the research was to map the level of awareness of the adult population in the context of modern prevention of cardiovascular diseases. Methods: To verify the hypotheses, we used the tools of inductive statistics, Chi-square test. We made the decision about the significance of the differences based on the calculated value and a significance level of 0.05.Results: Through a deeper analysis, we found that the awareness about modern prevention of cardiovascular diseases, i.e., the consumption of black coffee, red wine 0.2 dl per day, 70% dark chocolate, and Omega 3 fatty acids is unsatisfactory among our selected sample of respondents. We also found a statistically significant relationship between cardiology diagnoses and BMI in a selected sample of respondents. The frequency of cardiology examinations has an effect on respondents' awareness of modern prevention of cardiovascular diseases.Conclusion: The role of the prevention and reduction of risk factors in society is not only a small part necessary to prevent the occurrence and spread of cardiovascular diseases, it is an important element needed to improve the overall health of the population. Such prevention can be achieved mainly by providing sufficient information and supporting and motivating individuals to have a better lifestyle, as well as by creating greater interest and responsibility for their own health
Study of absorption and emission spectra of substituted terthiophene compounds by methods of theoretical chemistry
No full textTerthiophene derivatives attract interest due to their prospective applications in optoelectronic or sensor devices. Due to their nontoxicity they can be considered as suitable candidates in biological applications. Supramolecular organization of the matter is one of the most interesting topics in contemporary materials science. Amphiphilic chromophores based on substituted terthiophenes are capable of self-assembly into supramolecular architectures. In this work, we aim at simulation of the spectral properties of terthiophene with oligo(ethylene oxide) substituents by the methods of quantum chemistry and molecular dynamics (MD). The potential energy surface (PES) of this molecule was determined by the methods of density functional theory (DFT) for the ground state and time-dependent density-functional theory (TD-DFT) for the excited state. MD simulations in water than revealed the most frequented molecular conformations in both these states. Absorption and fluorescence spectra were determined for all these conformations, including the surrounding water molecules, using TD-DFT and averaged over the conformation space to obtain the final absorption and fluorescence spectrum. The calculated spectra were compared with their experimental counterparts and the differences were discussed in context of the supramolecular structure revealed by confocal microscopy. In spite of its simplicity, this approach provides a satisfactory approximation of absorption and fluorescent spectra of these molecules obtained by computational methods.Tomas Bata University in Zlín, TBU, (IGA/FT/2023/006); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMTTomas Bata University in Zli