Tomas Bata University in Zlín
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Preparing O/W/O emulsion for curcumin (curcuma longa) delivery and in vitro digestibility assay
Get PDFIn this study, simple oil-in-water emulsions (O/W) and multiple O/W/O emulsions were employed as carriers for a curcumin delivery system. The stability of emulsions was evaluated using DSC (differential scanning calorimetry), accompanied by particle size measurement by DLS (dynamic light scattering) and rheological analysis. The amount of freezable water (Wfs) in O/W emulsion was determined to be 80.4%, while that in O/W/O emulsion was 23.7%. Multiple emulsions had a more complex structure than simple emulsions, being characterized by higher stability with predominant loss modulus over storage modulus (G” > G’). The mean surface diameter for O/W emulsion was 198.7 ± 9.8 nm, being approximately two times lower than that for multiple emulsions. Curcumin in vitro digestibility was observed for both emulsions and, additionally, the digestibility of fresh and dried curcuma root powders was investigated. Multiple emulsions were found to be a superior matrix for curcumin delivery, with higher stability and emulsion digestibility of 50.6% for the stomach and small intestine. In vitro digestion of dried curcuma powders and curcuma root samples was monitored by HPLC (high-performance liquid chromatography). The DMD (dry matter digestibility) for dried curcuma powders ranged between 52.9% to 78.8%, and for fresh curcuma (KF) was 95.5%.This research was funded by the Tomas Bata University in Zlin, grant number IGA/FT/2024/005.Tomas Bata University in Zlin; [IGA/FT/2024/005
Plasma mediated immobilization of metformin on polyethylene: effects on drug release, antibacterial activity, and biocompatibility
Get PDFMetformin, a widely used antidiabetic drug, has gained attention for its potential applications in antimicrobial surfaces, delivery systems, and anticancer therapy. However, immobilizing metformin in a stable, bioactive, and dose-controllable manner onto a chemically inert, hydrophobic surface is challenging. The objective of this study is to immobilize metformin at various concentration (0.5, 1, 2, 5, 10, and 20 g·L−1) onto low-density polyethylene (LDPE) surfaces by a multistep approach with the aim of creating bioactive coatings. In this approach, LDPE was first treated with a 40 kHz low pressure plasma discharge in air atmosphere, followed by non-covalent attachment of acrylic acid via a grafting technique. Metformin was covalently attached to the surface via N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS) activation, while its presence on the polymer surface was confirmed by Water contact angle (WCA), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Sustained metformin release with a shift from Fickian to first-order kinetics was observed at higher drug loading. Antibacterial testing against Staphylococcus aureus and Escherichia coli showed no antibacterial effect at the selected concentration levels. Cytocompatibility assays with multipotent mesenchymal cells showed good biocompatibility of modified surfaces, with only dose-dependent cytotoxicity at higher metformin concentrations (>5 g·L−1). These results demonstrate that despite the absence of antibacterial effects, the developed system offers a promising platform for further biomedical applications requiring controlled drug surface functionalization and retained cytocompatibility.Ministry of Education, Youth and Sports of the Czech Republic [RP/CPS/2024-28/005, RP/CPS/2024-28/002]; Slovenian Research Agency [L2-3163, P2-0082]; Ministry of Education, Youth and Sports of the Czech Republic [LM2023039]; Operational Programme Johannes Amos Comenius OP JAC A'pplication [CZ.02.01.01/00/23_021/0009004]; Internal Grant Agency of Tomas Bata University in Zlin, Czech Republic [IGA/CPS/2025/005
How the rubber compounds of different tire's components heat up?
No full textIn general, there are more than a dozen different compounds used in the construction of a truck tire, whereas each compound used is formulated to optimize the overall tire performance, including heat generation. As a tire deflects, the hysteretic loss generated by all the compounds is the main source of heat build-up. Themoreatire deflects, the higher the hysteretic loss and the higher the heat build-up. This means that a tire that is overloaded or underinflated for the load its carrying will generate more heat. In addition, running at higher speeds or at higher ambient temperature will also increase heat build-up. Consequently, the increased tire temperatures in the individual parts are then one of the major causes of rubber degradation and can lead to fatigue cracking, belt separation, tread block tearing and chunking. Moreover, it can affect a tire's air permeability. Therefore, the aim of the current study is to investigate heat build-up of the real rubber compounds applied in to Multi-Purpose Tire (MPT). For that purpose, firstly the characterization of the fundamental mechanical behavior of these rubber compounds has been performed followed by systematic study of heat build-up inside and on the surface of the rubber test specimen during cyclic mechanical loading. Novel testing approach and fully instrumented facility labelled Heat Build-Up Analyzer (Coesfeld GmbH, Germany), which is based on multiaxial measuring capabilities such as dynamic multi-planar bending has been applied for the heat build-up characterization. Finally, the heat build-up properties of each rubber compound are discussed in relation to the relevant application in tire.OP RDE project The Development of Capacity for Research and Development of TBU in Zlin [CZ.02.2.69/0.0/0.0/16_028/0006243]; Ministry of Education, Youth and Sports of the Czech Republic-DKRVO [RP/CPS/2022/006
Solution of the modular PCM-based cooling ceiling and ventilation system
Get PDFMost newly constructed buildings are now built to energy-passive standards, which set requirements for specific heating demand, non-renewable primary energy use, building envelope airtightness, and the frequency of exceeding permissible indoor air temperatures in summer. These temperature exceedances relate to the room's thermal stability, determined by the potential for heat accumulation in surrounding structures over the daily cycle. For buildings with lightweight construction, implementing a Thermal Energy Storage (TES) solution can significantly enhance their energy accumulation ability. This article addresses the design and evaluation of a progressive cooling ceiling system combined with active ventilation system components, including the incorporation of TES based on PCM materials. The proposed solution aims to improve the thermal stability of occupied spaces, thereby significantly reduce the need for mechanical cooling. The research developed a new methodology for measuring the energy performance parameters of modular cooling ceiling systems, with its implementation thoroughly discussed. The evaluation of this solution was conducted within the context of the entire energy system for a reference building, considering various construction types (lightweight, medium, heavy). The overall potential energy savings range from 13% to 32%, depending on the building's construction, while still meeting the required thermal comfort criteria.European Regional Development Fund [CZ.1. 05/2.1.00/19.0376]; Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [MSMT-7778/2014]; Project IN-TERREG V-A SK-CZ/2019/11 [NFP304010Y280
Characterization of fibers prepared by centrifugal spinning from biotechnologically derived chicken gelatin
No full textThe application of biopolymer-based materials is increasing due to better sustainability and environmental protection properties. Gelatin fibers have a specific surface and high porosity, which is why their use in medicine and the food industry is being researched. This article explores the potential of centrifugal spinning to produce gelatin fibers. Gelatin for fiber preparation was obtained from a non-traditional source of collagen (chicken by-products) using a unique enzymatic process. The fiber quality was compared with those prepared from gelatins produced from traditional collagen tissues (porcine, bovine). The results showed that fibers cross-linked with glutaraldehyde vapor preserved their structure even in contact with water. Using a cross-linker controlled swelling ability and solubility while maintaining the fiber structure. On the contrary, uncross-linked gelatin fibers were water soluble due to a high surface-to-volume ratio, facilitating water penetration and dissolution. Scanning electron microscopy (SEM) provided a clearer picture of the morphology of gelatin fibers obtained by centrifugal spinning. Differences in the amount of bonding depending on the raw material used and the presence of a cross-linker were analyzed using Fourier transform infrared spectroscopy (FTIR). The overall results showed that chicken gelatin is a suitable alternative to gelatins from traditional sources and can be used for preparing food and pharmaceutical packaging and coatings, fibers, or bioprinting of 3D matrices.Internal Grant Agency of the Faculty of Technology of Tomas Bata University in Zlin [IGA/FT/2023/008]; Project Development of Recycling and Processing Technologies of the Faculty of Applied Informatics of Tomas Bata University in Zlin [RVO/CEBIA/2019/003
Numerical and experimental modal analysis of a gyroid Inconel 718 structure for stiffness specification in the design of load-bearing components
Get PDFThe study aims to investigate the modal properties of a 60 × 70 × 80 mm gyroid structure made of Inconel 718 with 67.5% porosity. The geometry model for sample production was created using the software PTC Creo, whereas the geometry model for numerical analysis was created using the Python application ScaffoldStructures. FE analysis was performed using ANSYS 2024 R1 software. Free boundary conditions were used in experimental modal analysis to ensure feasibility. The analysis identified the first four natural frequencies ranging from 10 to 16 kHz. The results revealed that the first natural frequency corresponds to the first torsional frequency about the Z axis, the second to the first flexural mode in the XZ plane, the third to the first bending mode in the YZ plane, and the fourth to the first torsional mode about the X axis. Small differences between the results of numerical and experimental modal analysis can be attributed to geometric errors in the manufactured sample, careless removal from the platform, and due to reduction in the complexity of the numerical FE model. Employing modal analysis of a component, the stiffness of a lightweight component can be revealed. In the case of the sample with the cellular structure of gyroid type, relatively high stiffness regarding the material savings was identified, which can be advantageously used in many applications.Ministry of Education, Science, Research and Sport of the Slovak Republic [APVV-19-0550]; KEGA [032TUKE-4/2022]Ministry of Education, Science, Research and Sport; Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky, (APVV-19-0550); Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky; KEGA, (032TUKE-4/2022); University of Rijeka, (uniri-iskusni-tehnic-23-112
Prediction of biaxial properties of elastomers and appropriate data processing
Get PDFAn equibiaxial tension test could be necessary to set up hyperelastic material constants for elastomers exactly. Unfortunately, very often, only uniaxial tension experimental data are available. It is possible to use only uniaxial data to compute hyperelastic constants for a hyperelastic model, but the prediction of behavior in different deformation modes (as is equibiaxial or pure shear) will not work correctly with this model. It is quite obvious that there is some relation between uniaxial and equibiaxial behavior for the elastomers. Thus, we could use uniaxial data to predict equibiaxial behavior. If we were able to predict (at least approximately) equibiaxial data, then we could create a hyperelastic model usable for the general prediction of any deformation mode of elastomer. The method of the appropriate processing of experimental data for such prediction is described in the article and is verified by the comparison with the experiment. The presented results include uniaxial and equibiaxial experimental data, the created average curve of both the deformation modes, and the predicted equibiaxial data. Using Student's t-test, a close coincidence of the real and predicted equibiaxial data was confirmed.Tomas Bata University in Zlin [IGA/FT/2024/002]Univerzita Tomáše Bati ve Zlíně, UTB, (IGA/FT/2024/002
Dye removal from tannery wastewater utilizing footwear waste: A sustainable approach
No full textWaste-to-3R (reduce, reuse, and recycle) is a promising mass balance approach in the leather sector for addressing the current challenge of overproduction of rubber sole waste in the footwear industry and dye pollution in tanneries. In this study, low-cost charcoal derived from discarded natural rubber (NR) soles was effectively employed to remove anionic and cationic dyes from a model tannery dye solution, aligning with mass balance approaches in the leather sector. Discarded rubber charcoal (DRC) was prepared at 350 degrees C using a self-fabricated pyrolytic cell. The resulting charcoal was then dried, ground, and separated through 40-mesh size lab-scale sieves, and it was subsequently employed for the removal of dyes from tannery wastewater. The dye removal performance was optimized by adjusting parameters such as dosage, pH, contact time, and concentration. The maximum adsorption capacity and removal efficiency of the anionic acid dye (AD) were found to be 158.22 mg/g and 88.39% at pH 1, respectively, while those of the cationic methylene blue dye were 166.18 mg/g and 85.53% at pH 12, respectively, between 15 and 30 min, depending on the DRC conditions. Fresh charcoal and dye-loaded charcoal were characterized through Fourier transform infrared spectroscopy, x-ray diffraction, Brunauer-Emmett-Teller, scanning electron microscope (SEM), and transmission electron microscope with Energy-Dispersive X-ray (EDX) Spectroscopy for respective functional groups and morphology studies, and zeta potential measurements were employed to characterize the charcoal surface charge. The SEM image revealed that the shape of the DRC particles resembles a honeycomb structure, with an average size of 573.56 mu m. The adsorption kinetic study indicates that the Freundlich isotherm model and pseudo-second-order kinetics were well-fitted for dye removal in this study. The charcoal exhibited robust stability, retaining its capacity of 57.42 mg/g of AD and 44.94 mg/g of MB dye after four reuse cycles. This resilience was observed in treatment with various desorption agents, including HCl, CH3COOH, NaOH, and C2H5OH. The findings of this study suggest that NR-derived charcoal could be used as a successful substitute for commercial activated carbon in wastewater treatment to get rid of the acid and basic dyes of the leather industry. Based on the observed results, a plausible mechanism was also proposed. Discarded rubber waste is pyrolyzed and converted into charcoal for the removal of dye from tannery wastewater. imageInstitute of Leather Engineering and Technology, University of Dhaka, Dhaka, Bangladesh; IGA project [IGA/CPS/204/005
Analysis of conducted and radiated emission on a self-oscillating capacitive touch sensing circuit
No full textWith the advent of smartphones, there has been a recent increase in the use of capacitive touch sensing for various Human Machine Interfaces (HMI). Capacitive-based touch sensing provides higher flexibility and cost-effectiveness than, methodologies such as resistive-based touch sensing. However, Capacitive-based touch sensing is more prone to disturbances such as Electromagnetic interference (EMI) and noise due to temperature variation. This effect becomes more dominating as the sensing excitation frequency increases. Traditional capacitance to digital circuits, such as sigma-delta capacitive sensing, requires multiple clock cycles to measure sensing capacitance, thus necessitating higher frequency operation. In turn, this produces challenges in Electromagnetic Emission while also increasing its susceptibility to EMI, such as false or ghost touch due to exposure of the sensing electrodes to various frequency electric fields. This paper discusses the conducted electromagnetic emission behavior of an external excitation-frequency independent self-oscillating capacitance-to-time converter, where sensing is done with a single clock cycle, and discusses radiated Electromagnetic emission of the touch sensing electrode. The proposed approach is suitable for touch-sensing applications, mainly when used in a noisy EMI environment, such as inside a vehicle within the Automotive industry.European Union's Horizon Europe research and innovation program under the Marie Sklodowska-Curie grant [101072881]; UKR
How is cut and chip wear influenced by the variation of the cross-link density within the conventional vulcanization system of natural rubber?
No full textThis paper extends previous studies by the authors that aimed to describe the effect of apparent cross-link density (CLD) of the rubber polymer networks on the fracture mechanism caused by cut and chip (CC) wear of natural rubber (NR), demonstrating the positive effect of conventional vulcanization (CV). This work is focused on the determination of the effect of CLD while keeping constant the accelerator-to-sulfur ratio A/S = 0.2, typical for CV systems. For this ratio, different sulfur quantities were chosen, and the concentration of the accelerator N-tert-butyl-benzothiazole sulphonamide (TBBS) was calculated to achieve CLDs in a range from 35 to 524 μmol·cm–3. Standard analyses such as tensile tests, hardness, rebound resilience and DIN abrasion were performed. From these analyses, the optimum physical properties of the NR-based rubber were estimated to be in the CLD range of approximately 60 to 160 μmol·cm–3. A CC wear analysis was performed with an Instrumented cut and chip analyzer (ICCA) and it was found that the highest CC wear resistance of the NR is in the CLD range of 35 to 100 μmol·cm–3. Furthermore, the effect of strain-induced crystallization (SIC) of NR on CC wear and its dependence on the CLD region was discussed. For the first time, we determine a CLD range for a CV system in which the material achieves both optimal mechanical properties and CC wear resistance.Ministry of Education, Youth and Sports of the Czech Republic-DKRVO, (RP_CPS_2024_28_006); Deutsche Forschungsgemeinschaft, DFG, (380321452/GRK2430); Deutsche Forschungsgemeinschaft, DFGMinistry of Education, Youth and Sports of the Czech Republic-DKRVO [RP_CPS_2024_28_006]; DFG (Deutsche Forschungsgemeinschaft) [380321452/GRK2430