Tomas Bata University in Zlín
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Aqueous photo-RAFT polymerization under ambient conditions: synthesis of protein-polymer hybrids in open air
No full textA photoinduced reversible addition-fragmentation chain-transfer (photo-RAFT) polymerization technique in the presence of sodium pyruvate (SP) and pyruvic acid derivatives was developed. Depending on the wavelength of light used, SP acted as a biocompatible photoinitiator or promoter for polymerization, allowing rapid open-to-air polymerization in aqueous media. Under UV irradiation (370 nm), SP decomposes to generate CO2 and radicals, initiating polymerization. Under blue (450 nm) or green (525 nm) irradiation, SP enhances the polymerization rate via interaction with the excited state RAFT agent. This method enabled the polymerization of a range of hydrophilic monomers in reaction volumes up to 250 mL, eliminating the need to remove radical inhibitors from the monomers. In addition, photo-RAFT polymerization using SP allowed for the facile synthesis of protein-polymer hybrids in short reaction times (<1 h), low organic content (≤16%), and without rigorous deoxygenation and the use of transition metal photocatalysts. Enzymatic studies of a model protein (chymotrypsin) showed that despite a significant loss of protein activity after conjugation with RAFT chain transfer agents, the grafting polymers from proteins resulted in a 3-4-fold recovery of protein activity.Fundacja na rzecz Nauki Polskiej, FNP; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Fonds de recherche du Québec, FRQ; Fonds de recherche du Québec – Nature et technologies, FRQNT, (301734); Fonds de recherche du Québec – Nature et technologies, FRQNT; National Science Foundation, NSF, (CHE 2401112, DMR 2202747); National Science Foundation, NSF; J. W. Fulbright Commission in the Czech Republic, (2022-21-1, RP/CPS/2022/007); Narodowa Agencja Wymiany Akademickiej, NAWA, (BPN/PPO/2022/1/00027); Narodowa Agencja Wymiany Akademickiej, NAWA; Narodowe Centrum Nauki, NCN, (DEC-2023/07/X/ST5/01484); Narodowe Centrum Nauki, NCNFonds de recherche du Quebec (FRQNT) [301734]; J. W. Fulbright Commission in the Czech Republic [2022-21-1]; Project DKRVO [RP/CPS/2022/007]; MEYS of the Czech Republic; National Science Centre within the MINIATURA project [DEC-2023/07/X/ST5/01484]; Foundation for Polish Science (FNP); NSF [CHE 2401112]; [DMR 2202747
Tribological properties of 3D printed materials in total knee endoprosthesis
Get PDFThe submitted paper deals with biotribological contact in total knee arthroplasty. The goal was to evaluate the influence of the metal component production technology on tribological parameters in defined environments. The reference sample was a standard available test ball made of the subject material, used in testing tribological properties by the "Ball on Pin" method. The preparation of the experiment consisted in the production of test disks from UHMWPE (Ultra High Molecural Weight Polyethylene) material and the production of a metal test component with a spherical surface. The condition of the experiment and the basis of this contribution is to compare the properties of conventionally produced metal material against 3D printing. Using the SLM method, a sample with a semi-spherical surface on a cylindrical shank was produced, which was subsequently ground and polished to reflect the characteristics of the standard supplied test ball. The last step was the production of a suitable fixture in order to fit the sample into the tribometer. The so-called dry friction of the heterogeneous Ti6Al4V–UHMWPE pair and the friction in a biological lubricating environment represented by bovine serum were evaluated. The evaluation of the contact surfaces took place using a profilometer and an electron microscope. The coefficient of friction was determined directly from the test device - tribometer.University of Defencegrant "Modern Technologies for the Processing of Advanced Materials Used for Interdisciplinary Applications" [FSI-S-22-7957
Targeted delivery of letrozole using a modified metal–organic framework as a promising candidate in breast cancer therapy
No full textMetal–organic framework (MOF) can play a carrier role for an anticancer drug like letrozole (LTZ). This study reports an innovative and pH-responsive drug delivery system based on chitosan (CS) and folic acid (FA)-coated MOF. Higher cellular penetration can occur through higher folate receptors on the surface of cancer cells compared to normal cells. Firstly, ZIF-8@LTZ nanoparticles were successfully synthesized with an excellent loading efficiency of about 92%. LTZ was loaded into ZIF-8 ports and then capped with the CS-FA conjugate. The synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy, zeta potential analysis, X-ray diffraction (XRD), circular dichroism, dynamic light scattering (DLS), and scanning electron microscopy (SEM). 5-Diphenyltetrazolium bromide (MTT) assay was used to investigate the toxicity of synthesized nanoparticles, and apoptosis assay was used to investigate the mechanism of cell death after treatment with nanoparticles. In vitro release study confirms the controlled release of LTZ at high-performance acidic pH in cancerous media. About 75% of LTZ was released during 120 h at pH 5, and 60% and 49% drug release was obtained for pH 6 and pH 7.4, respectively. The cell culture results confirmed that ZIF-8@LTZ@CS-FA was more toxic than ZIF-8@LTZ, and it is more effective for targeting of positive receptor cells in breast cancer. The results of apoptosis analysis confirmed that LTZ and its ZIF-8 derivatives significantly promote the activity of caspase 3/7 enzymes in MCF-7 cells. Moreover, the engineered nanocarrier can be a very promising candidate for targeted and controlled cancer treatment.Razi UniversityResearch Council of Razi University, Kermanshah, Ira
Resilience in preschool and elementary school teachers in the Czech Republic
Get PDFThis study explores the resilience of preschool and elementary school teachers (ISCED Level 1) in the Czech Republic. The data were gathered from a sample of 476 preschool teachers and 193 elementary school teachers using The Sense of Coherence Scale, a 29-item measure developed by Antonovsky. This scale consists of three dimensions, specifically comprehensibility, meaningfulness and manageability. The study related resilience with the school level (preschool or elementary school), education completed by teachers, duration of experience and age of teachers. As hypothesised, these teacher demographic variables are associated significantly with teacher resilience. Preschool teachers have significantly lower resilience than teachers from elementary schools. Teachers with higher education levels have higher resilience in the comprehensibility dimension. Finally, teachers with longer practice and with older age have significantly higher resilience than teachers with shorter practice and younger age. The findings are discussed within the Czech Republic educational and practice context.Tomas Bata University in Zlin project FSR FORD [5-6/2021-23/FHS/ 001
The Acoustic Index User's Guide: A practical manual for defining, generating and understanding current and future acoustic indices
No full textEcoacoustics, the study of environmental sound, is a rapidly growing discipline offering ecological insights at scales ranging from individual organisms to whole ecosystems. Substantial methodological developments over the last 15 years have streamlined extraction of ecological information from audio recordings. One widely used set of methods are acoustic indices, which offer numerical summaries of the spectral, temporal and amplitude patterns in audio recordings. Currently, the specifics of each index's background, methodology and the soundscape patterns they are designed to summarise, are spread across multiple sources. Critically, details of index calculation are sometimes scarce, making it challenging for users to understand how index values are generated. Discrepancies in understanding can lead to misuse of acoustic indices or reporting of spurious results. This hinders ecological inference, replicability and discourages adoption of these tools for conservation and ecosystem monitoring, where they might otherwise provide useful insight. Here we present the Acoustic Index User's Guide—an interactive RShiny web app that defines and deconstructs eight of the most commonly used acoustic indices to facilitate consistent application across the discipline. We break the acoustic indices calculations down into easy-to-follow steps to better enable practical application and critical interpretation of acoustic indices. We demonstrate typical soundscape patterns using a suite of 91 example audio recordings: 66 real-world soundscapes from terrestrial, aquatic and subterranean systems around the world, and 25 synthetic files demonstrating archetypal soundscape patterns. Our interpretation figures signpost specific soundscape patterns likely to be reflected in acoustic indices' values. This RShiny app is a living resource; additional acoustic indices will be added in the future through collaboration with authors of pre-existing and new indices. The app also serves as a best-practice template for the information required when publishing new acoustic indices, so that authors can facilitate the widest possible understanding and uptake of their indices. In turn, improved understanding of acoustic indices will aid effective hypothesis generation, application and interpretation in ecological research, ecosystem monitoring and conservation management.Engineering and Physical Sciences Research Council, EPSRC, (EP/V007866/1); Engineering and Physical Sciences Research Council, EPSRC; Leverhulme Trust, (RPG‐2020‐160, ECF‐2020‐571); Leverhulme TrustEngineering and Physical Sciences Research Council [EP/V007866/1]; Leverhulme Trust [RPG-2020-160, ECF-2020-571
The effect of packaging material and adjunct culture on the biogenic amine content, microbiological and textural properties of Dutch-type cheese
No full textThe aim of the study was to assess the effects of the packaging materials applied (shrink foil, copolymer coating and food wax) in combination with Lacticaseibacillus casei CCDM 198 microbial strain on biochemical, microbiological and textural properties of Dutch-type cheese during ripening (at 12 ± 1 °C for 168 days). A multivariate principal component analysis method based on a correlation matrix was employed to evaluate the relationships between basic chemical properties, textural and microbiological parameters, biogenic amine and free amino acid contents in relation to the packaging material used and the length of the ripening time. The use of different packaging materials did not have a significant effect on the salt content, fat content, and pH values, whereas significant differences were observed for dry matter content and textural properties development. The presence of Lacticaseibacillus casei CCDM 198 strain accelerated proteolysis in all samples. Shrink foil and food wax had similar effects on the development of biogenic amine content during ripening, while considerable differences were observed for the samples wrapped in copolymer coating. Copolymer coating in combination with Lacticaseibacillus casei CCDM 198 strain was able to reduce biogenic amine content by up to 28% after 168 days.Ministerstvo Zemědělství; National Agency for Agriculture Research, (QK1710156, LM2023069); Horizon 2020 Framework Programme, H2020, (857560, OP VVV CZ.02.1.01/0.0/0.0/17_043/0009632)Ministry of Agriculture of the Czech Republic; National Agency for Agriculture Research [QK1710156]; Research Infrastructure RECETOX RI [LM2023069]; H2020 CETOCOEN Excellence [857560]; OP VVV [CZ.02.1.01/0.0/0.0/17_043/0009632
Effect of gentamicin sulfate and polymeric polyethylene glycol coating on the degradation and cytotoxicity of iron-based biomaterials
Get PDFThe work is focused on the degradation, cytotoxicity, and antibacterial properties, of iron-based biomaterials with a bioactive coating layer. The foam and the compact iron samples were coated with a polyethylene glycol (PEG) polymer layer without and with gentamicin sulfate (PEG + Ge). The corrosion properties of coated and uncoated samples were studied using the degradation testing in Hanks’ solution at 37 °C. The electrochemical and static immersion corrosion tests revealed that the PEG-coated samples corroded faster than samples with the bioactive PEG + Ge coating and uncoated samples. The foam samples corroded faster compared with the compact samples. To determine the cytotoxicity, cell viability was monitored in the presence of porous foam and compact iron samples. The antibacterial activity of the samples with PEG and PEG + Ge against Escherichia coli CCM 3954 and Staphylococcus aureus CCM 4223 strains was also tested. Tested PEG + Ge samples showed significant antibacterial activity against both bacterial strains. Therefore, the biodegradable iron-based materials with a bioactive coating could be a suitable successor to the metal materials studied thus far as well as the materials used in the field of medicine.Agentúra na Podporu Výskumu a Vývoja, APVV; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Vedecká Grantová Agentúra MŠVVaŠ SR a SAV, VEGA, (02/00006/22); Vedecká Grantová Agentúra MŠVVaŠ SR a SAV, VEGA; International Visegrad Fund, IVF, (22310096); International Visegrad Fund, IVF; DKRVO, (RP/CPS/2022/005); Faculty of Natural Sciences UPJŠ in Košice, (vvgs-2023-2518)Slovak Research and Development Agency [APVV-20-0278]; VEGA [02/00006/22]; Ministry of Education, Youth and Sports of the Czech Republic [DKRVO RP/CPS/2022/005]; Internal scientific grant system of the Faculty of Natural Sciences UPJS in Kossice [vvgs-2023-2518]; Visegrad Grants from International Visegrad Fund [22310096
Shifting from sustained to delayed drug delivery systems: Encapsulated mesoporous silica-chitosan grafted polylactic acid-based composite approach
No full textThe current study demonstrates a desired drug delivery-controlled system with a wide range of release parameters. It illustrates the feasibility of carriers in the systems for extended and short drug release. Herein, mesoporous silica nanoparticles (MSNs) coated with chitosan (Cs) grafted polylactic acid (PLA) composite were fabricated by a sol-gel method in the form of micrometric porous particles (∼270 nm) with ζ-potential of −17.7 ± 1.7 mV and a specific surface area and total pore volume of 122700 cm2/g and 0.057 cm3/g, respectively. The prepared template of polymer-silica composite pores proved to be essential in the incorporation of Doxorubicin (Dox) drug molecules with adsorption capacity of 83.33 mg/g and encapsulation efficiency of 88 %. Dox was incorporated via the solvent diffusion method into the polymer-silica composites at suitable pH and concentration, resulting in solid drug dispersions. The silica-Cs-g-PLA composites showed greater effectiveness in the delayed release of the Dox with complete release after 10 days as compared to pristine MSNs and silica-Cs, which were completed after 12 h and 24 h, respectively. The drug release profiles were studied at different pH (2, 7, and 8), with maximum results obtained at pH 2. Both pristine MSNs and silica-Cs suffered from the burst effect, which was overcome by the grafting of PLA. The functionalized silica-Cs with PLA shows a significant change in the drug release properties from a sustained release process for pristine MSNs and silica-Cs to an enhanced delayed process for the silica-Cs-g-PLA composite, which makes this composite attractive for oral multi-particulate formulations of modified release.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Tomas Bata University in Zlín, TBU; Centre of Polymer Systems; DKRVO, (RP/CPS/2022/002)Ministry of Education, Youth and Sports of the Czech Republic - DKRVO [RP/CPS/2022/002
Unraveling the financial impact of COVID-19 on the tourism industry through a difference-in-difference analysis
No full textThe COVID-19 pandemic has had a significant and enduring effect on the tourism industry, specifically impacting travel agencies. To respond effectively, it is essential to comprehend the financial repercussions and challenges that these agencies confront. This study seeks to address existing gaps in knowledge by conducting a comprehensive examination of the tourism industry's financial performance in the post-COVID-19 era. Our methodology utilizes a Difference-In-Difference (D-I-D) approach, considering multiple investigations to establish a causal connection between the pandemic and the financial stability of tourism service providers. We analyse changes in the overall financial health of the tourism industry relative to other sectors both before and after the COVID-19 outbreak using Altman Z scores. Furthermore, we assess accounting harmonization across diverse jurisdictions and financial frameworks (IFRS, US GAAP, Czech GAAP, German HGB). Data is sourced from 11 multinational corporations in the tourism sector, supplemented with financial data from sectors such as Automotive, Manufacturing, Food and beverage, and Real Estate. Our empirical findings indicate that non-tourism entities experienced a 19% lower likelihood of bankruptcy post-COVID-19. This finding underscores the uniqueness of the tourism industry's challenges during the pandemic. In addition to these findings, we provide practical recommendations designed to assist companies in the tourism industry as they navigate the recovery phase following the pandemic. These insights are pivotal in enabling the industry to build resilient strategies and ensure its sustainability in a post-pandemic landscape.European Cooperation in Science and Technology, COST; NATO; COST, (CA22110); Tomas Bata University in Zlín, TBU, (IGA/FaME/2022/007); Tomas Bata University in Zlín, TBUCOST (European Cooperation in Science and Technology) [CA22110]; Internal Grant Agency of the Tomas Bata University in Zlin bearing [IGA/FaME/2022/007
Effect of personnel aspects on sustainable development of SMEs in the Visegrad region
No full textThe aim of the article is to quantify and evaluate the impact of personnel aspects on the sustainability of small and medium-sized enterprises in the business environment of the countries of the Vysehrad Group. Empirical research was carried out on a sample of 1,585 small and medium-sized enterprises in four countries of the European Union. The questionnaire was filled out by the owners or top managers of the enterprises. Correlation analysis and linear regression analysis were used to evaluate the scientific question and statistical hypotheses. The subject of the investigation was personnel risks, such as employee turnover, employee error rates, or employee interest in learning. Sustainable development was characterized as the company's ability to remain in the business environment for the next five years. The results yielded interesting findings. All personnel aspects affect the sustainability of the company. Employee turnover is the most important determinant that has the strongest influence on the company's survival in the business environment.EU Funds - OP Research, Development and Education in cooperation [CZ.02.2.69/0.0/0.0/16_027/0008464]; Ministry of Education, Youth and Sports, Czech Republi