Tomas Bata University in Zlín
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Biomass-derived Carbon dots and their coated surface as a potential antimicrobial agent
Get PDFCarbon dots (CDs) with an average diameter of 6.3 nm were synthesized from the medicinal seed extract of Syzygium cumini L. using one-pot hydrothermal synthesis. The prepared CDs exhibited excitation-dependent emission characteristics with photoluminescence (PL) emission maxima at an excitation of 340 nm. The CDs at 500 µg/mL displayed antimicrobial activities against four common pathogens. Both Staphylococcus aureus and S. epidermidis were completely eradicated by CDs within 12 h, compared to 24 h for Escherichia coli and Klebsiella pneumonia. The release of various oxygen species (ROS) was postulated to play a critical role in bacterial eradication. The CDs decorated on cotton fabric by ultrasonication also displayed good antibacterial activities against the above bacteria. The finding opens a plausible use of CDs in biomedical textiles with potent antimicrobial properties against both Gram-negative and Gram-positive bacteria.RP/CPS/2022/007; Tomas Bata University in Zlin, TBU: IGA/CPS/2022/002Ministry of Education, Youth and Sports of the Czech Republic Program-DKRVO [RP/CPS/2022/007]; Internal Grant Agency of Tomas Bata University in Zlin, Czech Republic [IGA/CPS/2022/002
Verification of finger positioning accuracy of an affordable transradial prosthesis
Get PDFWhether due to unpleasant events, injuries or illnesses, people lose the mobility of their hands. In extreme cases, amputation of the hand or hands can also occur. This paper deals with designing and fabricating an affordable transradial prosthesis using 3D printing and measuring finger positioning accuracy during a long-term test. The prosthesis’ design was inspired by the tested wire construction used in both low-cost commercial and do-it-yourself prostheses. The shape of the partial parts of the prosthesis was adapted for production using 3D printing. A high priority was also placed on using as few electronics as possible, while the used electronics also has to be affordable. Six MG995 servo motors were utilized to provide movement for the fingers, thumbs and wrist, and an Arduino Nano R3 was used to control their function. A control glove was subsequently developed to control the prosthesis, allowing accurate measurement of the angles of the finger’s distal phalanges. Their measured angle served as a reference for matching the angles on the prosthetic hand. To verify the prosthesis’s durability and the finger grip’s accuracy, a long-term test of 100,000 cycles, which repeated the western world’s finger-counting system from 0 to 5, was performed. It was determined that there is only a minor deviation from the initial finger position based on measurements of the accuracy of the finger position before and after the long-term test. Only minimal wear of functional parts after the long-term test was observed. No significant deviations from the desired finger angles were measured.IGA/CebiaTech/2023/00
Effect of chain extending cross-linkers on the disintegration behavior of composted PBAT/PLA blown films
Get PDFA biodegradable blend of PBAT—poly(butylene adipate-co-terephthalate)—and PLA—poly(lactic acid)—for blown film extrusion was modified with four multi-functional chain extending cross-linkers (CECL). The anisotropic morphology introduced during film blowing affects the degradation processes. Given that two CECL increased the melt flow rate (MFR) of tris(2,4-di-tert-butylphenyl)phosphite (V1) and 1,3-phenylenebisoxazoline (V2) and the other two reduced it (aromatic polycarbodiimide (V3) and poly(4,4-dicyclohexylmethanecarbodiimide) (V4)), their compost (bio-)disintegration behavior was investigated. It was significantly altered with respect to the unmodified reference blend (REF). The disintegration behavior at 30 and 60 °C was investigated by determining changes in mass, Young’s moduli, tensile strengths, elongations at break and thermal properties. In order to quantify the disintegration behavior, the hole areas of blown films were evaluated after compost storage at 60 °C to calculate the kinetics of the time dependent degrees of disintegration. The kinetic model of disintegration provides two parameters: initiation time and disintegration time. They quantify the effects of the CECL on the disintegration behavior of the PBAT/PLA compound. Differential scanning calorimetry (DSC) revealed a pronounced annealing effect during storage in compost at 30 °C, as well as the occurrence of an additional step-like increase in the heat flow at 75 °C after storage at 60 °C. The disintegration consists of processes which affect amorphous and crystalline phase of PBAT in different manner that cannot be understood by a hydrolytic chain degradation only. Furthermore, gel permeation chromatography (GPC) revealed molecular degradation only at 60 °C for the REF and V1 after 7 days of compost storage. The observed losses of mass and cross-sectional area seem to be attributed more to mechanical decay than to molecular degradation for the given compost storage times.RP/CPS/2022/002, RP/CPS/2022/003; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMTMinistry of Education, Youth, and Sports of the Czech Republic-DKRVO [RP/CPS/2022/003, RP/CPS/2022/002
Development of all-solid-state Li-ion batteries: From key technical areas to commercial use
Get PDFInnovation in the design of Li-ion rechargeable batteries is necessary to overcome safety concerns and meet energy demands. In this regard, a new generation of Li-ion batteries (LIBs) in the form of all-solid-state batteries (ASSBs) has been developed, attracting a great deal of attention for their high-energy density and excellent mechanical-electrochemical stability. This review describes the current state of research and development on ASSB technology. To this end, study of the literature and patents as well as market analysis over the last two decades were carried out, highlighting how scientific achievements have informed the application of commercially profitable ASSBs. Analyzing the patents registered over the past 20 years revealed that the number of them had increased exponentially-from only few per year in early 2000 to more than 342 in 2020. Published literature and patents on the topic declare a solid-state electrolyte (SSE) to be the main component of ASSBs, and most patented examples are referred to as solid inorganic electrolytes (SIEs), followed by solid polymer electrolytes (SPEs) and solid hybrid electrolytes (SHEs) in popularity. Investigation of company websites, social media profiles, reports, and academic publications identified 93 companies associated with ASSBs. A list of leading businesses in the solid-state battery sector was compiled, out of which 36 provided information on the ASSB units in their product portfolio for detailed analysis.Technology Agency of the Czech Republic, TACR: TK03030157Technology Agency of the Czech Republic, Theta Program [TK03030157
The influence of motivations to share knowledge in preventing knowledge sabotage occurrences: An empirically tested motivational model
Get PDFThe purpose of this research is to assess the impact of intrinsic and extrinsic motivations to share knowledge on knowledge sabotage, in order to shape a motivational model designed to reduce sabotage incidents in practice. It contributes to knowledge management literature broadening our understanding of knowledge sabotage, which has been highlighted as the most extreme counterproductive knowledge behaviour due to its deliberate nature of harming others for personal gain. In fact, even though knowledge sabotage has been widely identified in organizations, we still know too little about such a potentially dangerous phenomenon. In our empirical investigation, data collection took place through online questionnaires addressed to 329 employees and managers of heterogeneous companies from Europe. Data has been analysed employing a structural equation modelling (SEM) technique, whose results confirmed the relevance of this phenomenon and identified a negative relationship between intrinsic motivations to share knowledge and the phenomenon of knowledge sabotage. In the end, our conclusions can be useful to expand researchers' and practitioners' awareness of the most extreme counterproductive workplace behaviour that threatens the process of intra-organizational knowledge sharing
The impact of divergent algal hydrocolloids addition on the physicochemical, viscoelastic, textural, and organoleptic properties of cream cheese products
Get PDFThe aim of the current study was to evaluate the addition of different algal hydrocolloids (κ-carrageenan, ι-carrageenan, furcellaran, and sodium alginate) at three different concentrations (0.50, 0.75, and 1.00% w/w) on the physicochemical, viscoelastic, textural, and organoleptic properties of model cream cheese (CC) samples. On the whole, the highest viscoelastic moduli and hardness values of the CC samples were reported when κ-carrageenan was used. Furthermore, increasing the concentrations of the tested hydrocolloids led to increases in the viscoelastic moduli and hardness values of CC. Recommendations for softer-consistency CC production include the application of κ-carrageenan at a concentration of 0.50–0.75% (w/w) or the use of furcellaran and sodium alginate at a concentration of 1.00% (w/w). For the production of CC with a more rigid consistency, it is recommended to apply κ-carrageenan at a concentration higher than 0.75% (w/w).IGA/FT/2023/007Internal Grant Agency of Tomas Bata University in Zlin [IGA/FT/2023/007
Three-dimensional printing process for musical instruments: Sound reflection properties of polymeric materials for enhanced acoustical performance
Get PDFAcoustical properties of various materials were analyzed in order to determine their potential for the utilization in the three-dimensional printing process of stringed musical instruments. Polylactic acid (PLA), polyethylene terephthalate with glycol modification (PET-G), and acrylonitrile styrene acrylate (ASA) filaments were studied in terms of sound reflection using the transfer function method. In addition, the surface geometry parameters (Sa, Sq, Sz, and Sdr) were measured, and their relation to the acoustic performance of three-dimensional-printed samples was investigated. It was found that a higher layer height, and thus a faster printing process, does not necessarily mean poor acoustical properties. The proposed methodology also proved to be a relatively easy and rapid way to test the acoustic performance of various materials and the effect of three-dimensional printing parameters to test such a combination at the very beginning of the production process.Tomas Bata University in Zlin, TBU: IGA/FT/2023/006; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: RP/CPS/2022/003Ministry of Education, Youth, and Sports of the Czech Republic; project DKRVO [RP/CPS/2022/003]; TBU [IGA/FT/2023/006
Fe3O4 imbuing carboxymethyl cellulose/dextran sulfate nanocomposite hydrogel beads: an effective adsorbent for methylene blue dye pollutant
Get PDFIn this study, initially synthesized magnetic nanoparticles modified with citrate ions (MNPs/m-MNPs) were entrapped in aluminum-carboxymethyl cellulose/dextran sulfate beads to form hybrid nanocomposites (m-MNPs-C/D0.5) using a simple two-pot method. Sodium dodecyl sulfate surfactant was employed to develop a porous interconnected structure. The synergistic effect of the hybrid nanocomposites was studied for the parametric adsorption of methylene blue dye pollutant. The swelling ability of hybrid hydrogels was also studied for different solution pH. The results clearly indicated that equilibrium was reached faster at about 3 h for the m-MNPs-loaded magnetic beads (m-MNPs-C/D0.5), whereas at 6 h for the MNPs-loaded beads (MNPs0.4-C/D0.5) and the unloaded simple ones (MNPs0-C/D0.5). Experimental data modeling of adsorption kinetics and isotherms as well as thermodynamic study showed a good correlation with pseudo-second order kinetic and Langmuir models while the adsorption process on magnetic beads was exothermic. The maximum adsorption capacity for MNPs0-C/D0.5 and the optimized m-MNPs0.3-C/D0.5 hydrogel were 380 and 529 mg g−1, respectively. Furthermore, all hydrogels were perfectly regenerated and then reused for five adsorption-desorption cycles without apparent loss of stability that confirms their consideration as alternative and effective adsorbents for wastewater treatment. The manufactured beads were characterized by scanning electron microscopy/energy dispersive X-Ray, dynamic light scattering, X-ray diffraction, thermogravimetric analysis, vibrating sample magnetometer and fourier-transform infrared spectroscopy
The role of HR indicators on performance of Czech companies: A multi-sector perspective
Get PDFRooted in the perspective of role theory, the use of human resource indicators to improve performance is a hugely important area in the HRM field, but most of our understanding on this comes from prior research on large firms. Importantly, our study looks at under-researched area of HR indicators to examine the size of company and ownership structure on HR indicators and decision making comprehensively on small, medium-sized and large firms specifically in the context of Central European region such as Czech Republic. To address recent calls in the literature for an investigation of this nature, this research examined the role of size of company, ownership structure on HR indicators for organizational performance at micro level (employee perspective). Data were collected by using survey-based questionnaire from 896 managers working in the Czech companies at various sector level. Chi-square test and Z -score of P-value were used. The results demonstrate that size of company and ownership structure are the key drivers of HR indicators at the workplace. More importantly, our research also suggests that ownership structure positively influences decision making by using HR indicators. To date, there is fairly limited has been done on HR indicators with respect to size of company and ownership structure in the Central European region specially in Czech Companies. Importantly, this research contributes to the nascent literature that positions HR indicators as an effect mechanism at the organizational setting at different sectoral level. Our research also suggest measures of HR indicators and present implications for both research and managerial practice.IGA-K-TRINITY/2022/005Internal Grant Agency of FaME TBU; [IGA/FaME/2021/009]; [IGA-K- TRINITY/2022/005
Experimental and numerical description of the heat build-up in rubber under cyclic loading
No full textThis paper describes a new numerical method - within an ANSYS Workbench finite element method environment - for simulating the kinetics of the Heat Build-up process in rubber under cyclic multiaxial loading. A novel measuring setup controls a multiaxial load which forces the heat build-up by combining the dynamic alteration torque and multi-planar bending. In this method, the experimentally determined Heat Build-up is calculated numerically from the strain energy density with the determined hyperelastic material parameters at room temperature. A new quantity, the so-called dissipation constant, is introduced which makes it possible to determine the dissipation energy of cyclically loaded specimen. The experiments and calculations were carried out for a broad range of loading conditions, varying in both bending angle and rotational speed. Finally, the agreement between the experimentally determined and the calculated data is discussed.Ministry of Education, Youth and Sports of the Czech Republic - DKRVO [RP/CPS/2022/006]; project OP RDE Junior Grants of TBU in Zlin [CZ.02.2.69/0.0/0.0/19_073/0016941