Tomas Bata University in Zlín
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A coupled piezo-triboelectric nanogenerator based on the electrification of biaxially oriented polyethylene terephthalate food packaging films
No full textThis study reports that biaxially oriented silica-filled polyethylene terephthalate (BOPET) films used worldwide as food packaging materials combine unique dual electrification properties that enable the effective conversion of mechanical energy into electricity. The electricity output depends on the physical contact and separation of the polymeric matrix and triboelectric pair material with different affinities for electrons on its surface. To exploit the dual piezoelectric and triboelectric electrification of the films materials, a hybrid piezoelectric triboelectric nanogenerator energy harvester using this film as an electron source was assembled and tested. When BOPET film is paired with polyvinylidene fluoride (PVDF) nanofibre network, which due to the electronegativity difference gained electrons, the performance of the nanogenerator to the output open-circuit increases voltage values above 305 V, and the short-circuit current density and charge density to 12 ± 1 μAcm−2 and 37 ± 2 μCm−2, respectively. Further, underlaying the PVDF tribo-contact layer by a dielectric low permittivity spunbond non-woven polypropylene raises the performance of the nanogenerator more than doubled (624 V) with corresponding densities of 61 ± 7 μAcm−2 and 101 ± 4 μCm−2.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (RP/CPS/2022/003, RP/CPS/2022/007
Portfolio hedging strategy-metals and commodities
Get PDFFrom the perspective of portfolio management, hedging is a proactive risk management measure that aims to protect the portfolio from unwanted drawdown risk and avoid loss on investment by incorporating assets into a portfolio which moves in the opposite direction as the market. However, trying to limit the risk could result in limiting potential profits. Commodities are one of the best hedges against inflation as their price typically accelerates during such times providing benefit to the investor. We use the innovative approach of hedging commodities using a combination of CAPM and RSI Strategy to identify which of 9 observed hard commodities (Aluminium, Zinc, Nickel, Lead, Tin, Copper, Gold, Brent Oil and Natural Gas) should have been incorporated into investment portfolio during the period 2008-2023. The SML strategy is reviewed in the empirical analysis for its suitability as a hedging instrument compared to the RSI, which is regularly used to hedge metals and commodities. Our MS Excel and IBM SPSS software analysis showed that RSI was a better hedging strategy than SML in 21 out of 36 cases but without statistical significance
The influence of social media on brand personality towards consumer purchase intention in the telecom industry: A conceptual study
No full textThe emergence of social media has benefited industry in many forms, notable of which is the formation of a brand personality through firm communication practices. In the telecommunications industry, social media has been a useful tool for brand management. Considering the relationship between brand personality and consumer purchasing as established in numerous existing literature, this study aims to assess the influence of social media on the brand personality, with regards to consumer purchase intention in the telecommunications industry. To meet this objective, the study will review studies related to the current research theme, and conceptualize based on the findings of the studies. The search for paper was implemented with the use of scientific databases such as Web of Science, Scopus, Ebsco, Google Scholar, and other relevant journal databases. This article, not only adds deeper insight to the social media and brand personality literature, but also serves as a source of information for managers in the telecom industry on how to successfully deploy social media practices in the management of their firms' brand. This research will build on and contribute to previous brand personality and consumer psychology literature by examining the influence of social media on roles of brand personality. Limitations and future research directions are presented at the end of the paper. © 8th European Conference on Social Media, ECSM 2021.Univerzita Tomáše Bati ve Zlíně: IGA/FaME/2020/00
Atomic Fe on hierarchically ordered porous carbon towards high-performance Lithium-sulfur batteries
Get PDFLithium-sulfur (Li-S) battery is the promising next-generation energy storage device owing to its ultra-high theoretical energy density and low cost. Unfortunately, its practical performance is significantly hindered by the poor conductivity of sulfur, huge volume change, and soluble lithium polysulfides (LiPSs). To address above issues, single iron (Fe) atoms anchored on hierarchically porous carbon substrate configured by ordered macropores and widespread mesopores/micropores (Fe[sbnd]N[sbnd]C/OC) are synthesized and acted as carbon hosts for sulfur cathodes. Single Fe atoms in Fe-N4 moieties serve as active sites to accelerate conversion kinetics of LiPSs due to strong catalytic ability, thereby the shuttle effect being obviously restrained. Meanwhile, the trimodal-porous structure provides continuous carbon framework for enhanced electrical conductivity, ordered macroporous channels bridged by mesopores for rapid Li+ diffusion, and adequate spaces to reserve sulfur volume oscillation. Consequently, sulfur-loaded Fe[sbnd]N[sbnd]C/OC (Fe[sbnd]N[sbnd]C/OC/S) cathodes exhibit an impressive specific capacity of 1442 mAh g−1 at 0.1C and maintain the capacity retention of 89.2 % after 300 cycles at 1C. It offers fresh insights for designing efficient sulfur hosts to enhance the performance of Li-S batteries. © 2022 Elsevier B.V.LTT20005; 21PJD018; National Natural Science Foundation of China, NSFC: 22108079; China Postdoctoral Science Foundation: 2020M681208National Natural Science Foundation of China [22108079]; Shanghai Pujiang Program [21PJD018]; China Postdoctoral Science Foundation [2020M681208]; Czech Ministry of Education, Youth and Sports INTER -EXCELLENCE [LTT20005]; Feringa Nobel Prize Scientist Joint Research Cente
Adamantane-substituted purine nucleosides: Synthesis, host–guest complexes with β-cyclodextrin and biological activity
Get PDFPurine nucleosides represent an interesting group of nitrogen heterocycles, showing a wide range of biological effects. In this study, we designed and synthesized a series of 6,9-disubstituted and 2,6,9-trisubstituted purine ribonucleosides via consecutive nucleophilic aromatic substitution, glycosylation, and deprotection of the ribofuranose unit. We prepared eight new purine nucleosides bearing unique adamantylated aromatic amines at position 6. Additionally, the ability of the synthesized purine nucleosides to form stable host-guest complexes with beta-cyclodextrin (beta-CD) was confirmed using nuclear magnetic resonance (NMR) and mass spectrometry (ESI-MS) experiments. The in vitro antiproliferative activity of purine nucleosides and their equimolar mixtures with beta-CD was tested against two types of human tumor cell line. Six adamantane-based purine nucleosides showed an antiproliferative activity in the micromolar range. Moreover, their effect was only slightly suppressed by the presence of beta-CD, which was probably due to the competitive binding of the corresponding purine nucleoside inside the beta-CD cavity./0.0/0.0/18_046/0015974, CZ.02.1.01; IGA/FT/2019/007, IGA/FT2018/001; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: LM2018127; Grantová Agentura České Republiky, GA ČR: 21-06553SInternal Founding Agency of Tomas Bata University in Zlin [IGA/FT2018/001, IGA/FT/2019/007]; Czech Science Foundation [21-06553S]; MEYS CR [LM2018127]; European Regional Development Fund-Project "UP CIISB" [CZ.02.1.01./0.0/0.0/18_046/0015974
Controlled release of vitamin U from microencapsulated brassica oleracea l. var. capitata extract for peptic ulcer treatment
Get PDFCabbage plant (Brassica oleracea L. var. capitata) contains compounds such as polyphenols, minerals, and ascorbic acid, as well as some amino acids such as glutamine, which has anti-inflammatory properties. In addition, its nutrient contains the component of vitamin U (S-methylmethionine) which is effective in the treatment and prevention of peptic ulcer disease. The aim of this study is to perform microencapsulation of Brassica oleracea L. var. capitata extract for controlled release of vitamin U for peptic ulcer treatment. Within this scope, vitamin U and some amino acids (L-methionine, L-glutamine, L-histidine, L-lysine, L-aspartic acid) were extracted from a cabbage by extraction methods and microencapsulated. The gelatin/gum Arabic and gelatin/sodium alginate polymer complexes were used as wall materials. Morphological analysis of the microcapsules showed that the microcapsules had a homogeneous, spherical shell structure. The results of HPLC analysis confirmed that vitamin U and amino acid compounds in cabbage extract are also present in the structure of microcapsules. FTIR analysis confirmed the interaction between shell materials and microcapsules, and the similarities in the bands of the plant extract and microcapsules indicated microencapsulation of the plant extract successfully. In vitro release testing of the microcapsules was studied in simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 7.4) for 48 h. The maximum encapsulation efficiency and release were obtained as 86.92% and 93.6% for the gum Arabic-contained microcapsule, respectively.RP/CPS/2022/001, RP/CPS/2022/005; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK; Süleyman Demirel Üniversitesi, SDÜ: FDK-2019-7330; Milli Eğitim Bakanliği, MEBMinistry of Education, Youth and Sports of the Czech Republic - DKRVO [RP/CPS/2022/001, RP/CPS/2022/005]; TUBITAK 2214-A International Research Fellowship Programme; Suleyman Demirel University Scientific Research Projects Coordination Unit [FDK-2019-7330]; Ministry of Educatio
The impact of investment decisions on firm financial performance moderated by economic policy uncertainty: Evidence from the manufacturing sector of Pakistan
No full textThe study examines the link between firm-level investment and firm performance moderated by economic policy uncertainty in the manufacturing sector of Pakistan across the six years from 2015–2020. The System-GMM estimation has been employed to demonstrate the problem of endogeneity with dynamic linear and non-linear models. The study revealed that the moderating impact of economic policy uncertainty has negative and significant impact on investment (investment in tangible assets, investment in intangible assets, and financial leverage) and firm performance (Tobin’s Q). Similarly, economic policy uncertainty regarding investment and firm performance (ROA) is negative and significant in investment in tangible assets, but positive and significant in financial leverage. Our findings remain constant over a range of variable characteristics, even after accounting for endogeneity issues. Our main contribution is the finding that investment and firm performance have a negative and significant relationship with economic policy uncertainty. As economic policy uncertainty raises the firm level, investment decreases, which ultimately impacts firm performance negatively. Thus, the study advises that policymakers make an effort to minimize the effect of economic policy uncertainty at a certain level. They must keep this uncertainty within a reasonable range since increased economic policy uncertainty will push businesses to minimize their short-term and long-term investments. © 2022 AESS Publications. All Rights Reserved.IGA/FaME/2022/00
Spirulina microalgae blend with biohydrogen and nanocatalyst TiO2 and Ce2O3 as step towards emission reduction: Promoter or inhibitor
No full textExtensive use of fossil fuels is the main cause for global warming. Burning of fossil fuels increases the air pollution which leads to adverse human health effects. Biodiesel is one the promising source of the energy to replace fossil fuel. The current study focused on one of the most sustainable microalgae biodiesel blends in the diesel engine. Further, the nanoparticles such as TiO2 and Ce2O3 were sonicated with the blends at the rate of 50 ppm to increase the brake thermal efficiency with least production of the pollutants. In addition to above, the hydrogen is also used as the secondary fuel to enhance the performance and combustion characteristics of the spirulina biodiesel. The constant hydrogen flow rate of 10 L/min was maintained throughout the study. Compared to the diesel fuel, biodiesel blends reported higher BTE due to the oxygenated additives and hydrogen addition. The maximum thermal efficiency for blend B30TH was found to be 29.5 % and minimum specific fuel consumption has been obtained for B30CH at maximum brake power conditions. In all test conditions, the biodiesel blends with hydrogen reported higher in-cylinder pressure and heat release rate. With regard to the emission, adding the biodiesel blends increases the combustion rates which leads to the reduction of accumulation of pollutants such as carbon monoxide, carbon dioxide, hydrocarbons, nitrogen of oxides and smoke. Among the various blends B20CH reported a massive reduction in the emission than B20TH.Van Lang University, Vietnam; King Saud University, Riyadh, Saudi Arabia [RSP-2021/385]RSP-2021/385; King Saud University, KS
The influence of ply stacking sequence on mechanical properties of carbon/epoxy composite laminates
Get PDFIn this work, the effect of ply stacking sequence of carbon/epoxy laminates subjected to flexural, tensile and impact loading was investigated. Five laminates with different stacking configurations were produced using the hand-laying-up technique. This includes a unidirectional laminate, cross-ply laminates, and quasi-isotropic laminates. Following the autoclave curing process, the responses of the composites to bending, tension and impact force were determined according to ASTM standards, and their corresponding strength, stiffness as well as impact energy were evaluated. Likewise, the flexural failure mode associated with each laminate was characterised using an optical microscope. The unidirectional laminates have higher flexural and tensile strength compared to the cross-ply and quasi-isotropic laminates. Moreover, as a result of material symmetry, the flexural and tensile modulus of symmetric cross-ply laminate improved by 59.5% and 3.97% compared to the unsymmetric counterpart. Furthermore, the quasi-isotropic laminates with absorption energy of 116.2 kJ/m2 and 115.12 kJ/m2, respectively have higher impact resistance compared to other samples.Tomas Bata University in Zlin, TBU: CZ.02.1.01/0.0/0.0/17_049/0008407, IGA/FT/2023/004; European Commission, ECInternal grant of TBU in Zlin; project "Innovative and additive manufacturing technologynew technological solutions for 3D printing of metals and composite materials" [IGA/FT/2023/004]; Structural Funds of the European Union project; [CZ.02.1.01/0.0/0.0/17_049/0008407
Trendy w technologiach bezpieczeństwa
No full textModern safety technologies are constantly advancing safety and health at work. The article dealt with new trends in security technologies. Speed is required in many industries. It is also reflected in security technologies. Every newly created risk must be responded to quickly. The innovations on the side of ensuring security also correspond to this. This publication aims to analyze current new security technologies and the possibilities of their use in companies.IGA/FAI/2022/00