Tomas Bata University in Zlín
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Antibacterial porous systems based on polylactide loaded with amikacin
Get PDFThree porous matrices based on poly(lactic acid) are proposed herein for the controlled release of amikacin. The materials were fabricated by the method of spraying a surface liquid. Description is given as to the possibility of employing a modifier, such as a silica nanocarrier, for prolonging the release of amikacin, in addition to using chitosan to improve the properties of the materials, e.g., stability and sorption capacity. Depending on their actual composition, the materials exhibited varied efficacy for drug loading, as follows: 25.4 ± 2.2 μg/mg (matrices with 0.05% w/v of chitosan), 93 ± 13 μg/mg (with 0.08% w/v SiO2 amikacin modified nanoparticles), and 96 ± 34 μg/mg (matrices without functional additives). An in vitro study confirmed extended release of the drug (amikacin, over 60 days), carried out in accordance with the mathematical Kosmyer–Pepas model for all the materials tested. The matrices were also evaluated for their effectiveness in inhibiting the growth of bacteria such as Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Concurrent research was conducted on the transdermal absorption, morphology, elemental composition, and thermogravimetric properties of the released drug.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: RP/CPS/2022/002; Politechnika Gdańska, GUTMinistry of Education, Youth, and Sports of the Czech Republic [RP/CPS/2022/002
EU Cohesion Policy in the Czech Republic and Poland: Comparison of intervention areas among regions
Get PDFThe cohesion policy of the European Union represents a significant part of its budget and delivers interventions across all regions of the EU. There is little consensus on its efficiency, and its links to fostering convergence on the regional level are uncertain. Nevertheless, regions were shown to benefit from policy interventions promoting their growth and development. The main objective of the policy is to reduce regional disparities that exist among lagging and other, more developed regions. Therefore, this paper focuses on the deliverance of the cohesion policy in Central and Eastern European countries, Poland and the Czech Republic. It explores the support of thematic interventions across its regions in the 2014-2020 period. Findings point out different thematic support of Polish regions according to their relative advancement. Lagging regions of Poland received more substantial support related to promoting the endogenous potential for development and increase in quality of human capital. In contrast, the Czech regions were treated comparably regardless of their development stages. This points to different approaches to implementing the cohesion policy in these countries.[RO/2022/07
In-situ coating of leather with conducting polyaniline in colloidal dispersion mode
Get PDFFour different leathers and a nonwoven fibrous mat have been coated with a conducting polymer, polyaniline, in situ during the oxidation of aniline hydrochloride in the presence of poly(N-vinylpyrrolidone) stabilizer. This colloidal dispersion approach prevented the undesirable formation of free polyaniline precipitate outside the leather fibers. The molecular structure of polypeptide fibers with deposited polyaniline is discussed on the basis of FTIR spectra. Raman spectroscopy confirmed that individual fibers were coated with a conducting polymer. The cross-sectional optical microscopy revealed that the leather was coated on both sides. The layer thickness, tens to hundreds micrometers, was determined by the penetration depth of reaction mixture. In the case of diabetic insole mat gambrela, polyaniline penetrated throughout the sample body. This was also confirmed by the measurement of transversal resistance. The typical sheet resistance was in units to hundreds k omega/sq and differed but was of the same order of magnitude on top and bottom sides. The samples were subject to cyclic bending and of the resistivity changes have been monitored. Antibacterial activity of some leathers improved after the coating with polyaniline.Technology Agency of the Czech Republic, TACR; Tomas Bata University in Zlin, TBU: TP01010006Tomas Bata University in Zlin [TP01010006]; Technology Agency of the Czech Republi
Introduction of an adhesion factor to cube in cube models and its effect on calculated moduli of particulate composites
Get PDFThe cube in cube approach was used by Paul and Ishai-Cohen to model and derive formulas for filler content dependent Young's moduli of particle filled composites assuming perfect filler matrix adhesion. Their formulas were chosen because of their simplicity, and recalculated using an elementary volume approach which transforms spherical inclusions to cubic inclusions. The EV approach led to expression of the composites moduli that allows introducing an adhesion factor kadh ranging from 0 and 1 to take into account reduced filler matrix adhesion. This adhesion factor scales the edge length of the cubic inclusions, thus reducing the stress transfer area between matrix and filler. Fitting the experimental data with the modified Paul model provides reasonable k(adh) for PA66, PBT, PP, PE-LD and BR which are in line with their surface energies. Further analysis showed that stiffening only occurs if k(adh) exceeds root E-M/E-F and depends on the ratio of matrix modulus and filler modulus. The modified model allows for a quick calculation of any particle filled composites for known matrix modulus E-M, filler modulus E-F, filler volume content v(F) and adhesion factor k(adh). Thus, finite element analysis (FEA) simulations of any particle filled polymer parts as well as materials selection are significantly eased. FEA of cubic and hexagonal EV arrangements show that stress distributions within the EV exhibit more shear stresses if one deviates from the cubic arrangement. At high filler contents the assumption that the property of the EV is representative for the whole composite, holds only for filler volume contents up to 15 or 20% (corresponding to 30 to 40 weight %). Thus, for vast majority of commercially available particulate composites, the modified model can be applied. Furthermore, this indicates that the cube in cube approach reaches two limits: (i) the occurrence of increasing shear stresses at filler contents above 20% due to deviations of EV arrangements or spatial filler distribution from cubic arrangements (singular), and (ii) increasing interaction between particles with the formation of particle network within the matrix violating the EV assumption of their homogeneous dispersion.Ministry of Education, Youth and Sports of the Czech Republic-DKRVO [RP/CPS/2022/003
PLA/PHB-based materials fully biodegradable under both industrial and home-composting conditions
Get PDFIn order to make bioplastics accessible for a wider spectrum of applications, ready-to-use plastic material formulations should be available with tailored properties. Ideally, these kinds of materials should also be "home-compostable" to simplify their organic recycling. Therefore, materials based on PLA (polylactid acid) and PHB (polyhydroxybutyrate) blends are presented which contain suitable additives, and some of them contain also thermoplastic starch as a filler, which decreases the price of the final compound. They are intended for various applications, as documented by products made out of them. The produced materials are fully biodegradable under industrial composting conditions. Surprisingly, some of the materials, even those which contain more PLA than PHB, are also fully biodegradable under home-composting conditions within a period of about six months. Experiments made under laboratory conditions were supported with data obtained from a kitchen waste pilot composter and from municipal composting plant experiments. Material properties, environmental conditions, and microbiology data were recorded during some of these experiments to document the biodegradation process and changes on the surface and inside the materials on a molecular level.IGA/FT/2022/006; Agentúra na Podporu Výskumu a Vývoja, APVV: 313011V336, APVV-20-0193, APVV-20-0256; European Regional Development Fund, ERDF: FCH-S-21-7553Internal Grant Agency [IGA/FT/2022/006]; Slovak Research and Development Agency [APVV-20-0256, APVV-20-0193]; European Regional Development Fund [313011V336]; Specific University Research Grant [FCH-S-21-7553
Vanadium metal-organic frameworks derived VOx/Carbon nano-sheets and paperclip-like VOx/nitrogen-doped carbon nanocomposites for sodium-ion battery electrodes
Get PDFIn this work, vanadium metal-organic framework derived VOx/carbon and VOx/N-doped carbon nanocomposites are presented. The methodology introduced here is based on a novel polyol synthesis of vanadium metal-organic frameworks (MOFs) involving a microwave-assisted solvothermal reaction of vanadyl acetylacetonate with biphenyl-4,4'-dicarboxylic acid (Bpdc) and/or 2,2'-bipyridine-4,4'-dicarboxylic acid (NBpdc) in diethylene glycol (DEG) at the temperature of 230 degrees C. The V-based MOFs, labeled as V-Bpdc and V-NBpdc, were used as precursors for the preparation of VOx/carbon and VOx/N-doped carbon nanocomposites with unique sponge-like nano-sheet and paperclip-like morphology, respectively. The nanocomposites were obtained via thermal transformation of as-prepared vanadium MOFs in the argon atmosphere at 600 degrees C. The VOx/carbon sample consists of nano-sheets with the thickness 5-20 nm while the VOx/N-doped carbon paperclip-like nanocomposite has a rod diameter 35-70 nm. It was found that the approach reported here provides an effective and simple preparation pathway of carbon-based nanocomposites containing homogeneously distributed VOx species. Both V-MOFs and V-MOF-derived nanocomposites were characterized by the variety of physicochemical methods. In the following step, the obtained nanocomposites were investigated as electrode materials in sodium-ion batteries. Based on the obtained results, high electrochemical activities of VOx/carbon and VOx/N-doped carbon nanocomposites were evidenced. Particularly, in the case of VOx/N-doped carbon-based electrode, high capacity and low irreversible capacity were achieved. Therefore, reported materials are found to be promising candidates for electrode materials in sodium-ion batteries.FEKT-S-20-6206; INTER-TRANSFER LTT19001, RP/CPS/2020/006; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: LM2018110, LM2018127; Central European Institute of Technology, CEITEC; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.0409; Masarykova Univerzita, MUMinistry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504]; DKRVO [RP/CPS/2020/006]; INTER-TRANSFER [LTT19001]; Operational Program Research and Development for Innovations - European Regional Development Fund; national budget of the Czech Republic [CZ.1.05/2.1.00/19.0409]; BUT specific research program [FEKT-S-20-6206]; MEYS CR [LM2018127, LM2018110
Reuse of textile waste to production of the fibrous antibacterial membrane with filtration potential
Get PDFWasted synthetic fabrics are a type of textile waste source; the reuse of them brings environmental protection and turns waste into a valuable material. In this work, the used nylon (polyamide) stockings were transmuted into a fine fibrous membrane via an electrospinning process. In addition, the safety antibacterial agent, monoacylglycerol (MAG), was incorporated into a recycled fibrous membrane. The results revealed that the neat, recycled polyamide (rPA) fibers with a hydrophobic surface could be converted into hydrophilic fibers by blending various amounts of MAG with rPA solution prior to electrospinning. The filtration efficiency and air/water vapor permeability of the two types of produced membranes, neat rPA, and rPA/MAG, were tested. Their filtration efficiency (E100) was more than 92% and 96%, respectively. The membranes were classified according to Standard EN1822, and therefore, the membranes rPA and rPA/MAG were assigned to the classes E10 and E11, respectively. The air permeability was not affected by the addition of MAG, and water vapor permeability was slightly enhanced. Based on the obtained data, prepared rPA/MAG fibrous membranes can be evaluated as antifouling against both tested bacterial strains and antimicrobial against S. aureus. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Technology Agency of the Czech Republic, TACR: TJ04000226; Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky; Vedecká Grantová Agentúra MŠVVaŠ SR a SAV, VEGA: 2/0168/2
Value stream mapping of ocean import containers: A process cycle efficiency perspective
Get PDFInternational cargo transportation is majorly dependent on marine transport, which moves 80% of the international cargo. With the increase in vessel size and the same yard area available for container transportation, it is important to study the processes and understand the efficiency of the container operations process. This research paper aims to review the import container transportation process and understand the process cycle efficiency through lean six sigma concepts. The process is evaluated from the operations process perspective and documentation process at one of the ports of India. The research has been designed by conducting an industry expert review on the process of container transportation from vessel berthing to gate out for import containers, utilising lean six sigma principles such as value stream mapping (VSM) and process cycle efficiency. The results have contributed to the existing knowledge in identifying the waste in the container handling process and demonstrated the inefficiency in the system from the perspective of waiting time of containers due to customs examination, scanning, and inter-terminal handling and movement. The process cycle efficiency of 40% is calculated by analysing the detailed time of handling containers from vessel berthing to gate out. A new future value stream mapping is proposed considering the process cycle efficiency. Future studies will focus on studying this process for export containers and benchmarking the results with the top-performing ocean ports globally.IGA/FaME/2021/002Internal Grant Agency of FaME TBU in Zlin [IGA/FaME/2021/002
Accurate X-ray absorption spectra near L- and M-edges from relativistic four-component damped response time-dependent density functional theory
Get PDFThe simulation of X-ray absorption spectra requires both scalar and spin-orbit (SO) relativistic effects to be taken into account, particularly near L- and M-edges where the SO splitting of core p and d orbitals dominates. Four-component Dirac-Coulomb Hamiltonian-based linear damped response time-dependent density functional theory (4c-DR-TDDFT) calculates spectra directly for a selected frequency region while including the relativistic effects variationally, making the method well suited for X-ray applications. In this work, we show that accurate X-ray absorption spectra near L-2,L-3- and M-4,M-5-edges of closed-shell transition metal and actinide compounds with different central atoms, ligands, and oxidation states can be obtained by means of 4c-DR-TDDFT. While the main absorption lines do not change noticeably with the basis set and geometry, the exchange-correlation functional has a strong influence with hybrid functionals performing the best. The energy shift compared to the experiment is shown to depend linearly on the amount of Hartee-Fock exchange with the optimal value being 60% for spectral regions above 1000 eV, providing relative errors below 0.2% and 2% for edge energies and SO splittings, respectively. Finally, the methodology calibrated in this work is used to reproduce the experimental L-2,L-3-edge X-ray absorption spectra of [RuCl2(DMSO)(2)(Im)(2)] and [WCl4(PMePh2)(2)], and resolve the broad bands into separated lines, allowing an interpretation based on ligand field theory and double point groups. These results support 4c-DR-TDDFT as a reliable method for calculating and analyzing X-ray absorption spectra of chemically interesting systems, advance the accuracy of state-of-the art relativistic DFT approaches, and provide a reference for benchmarking more approximate techniques.Research Council of NorwayResearch Council of Norway [315822, 252569]; Ministry of Education, Youth and Sports of the Czech Republic -DKRVO [RP/CPS/2020/006]; Slovak Grant Agency VEGAVedecka grantova agentura MSVVaS SR a SAV (VEGA) [2/0135/21, APVV-19-0516]; Slovak Grant Agency APVVSlovak Research and Development Agency [2/0135/21, APVV-19-0516]; UNINETT Sigma2, the National Infrastructure for High Performance Computing and Data Storage in Norway [NN4654K]; Ministry of Education, Youth and Sports of the Czech Republic through the e-INFRA CZ [90140]RP/CPS/2020/006; NN4654K, Sigma2; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: 90140; Norges Forskningsråd: 252569, 315822; Vedecká Grantová Agentúra MŠVVaŠ SR a SAV, VEGA: 2/0135/21, APVV-19-051
Effect of calcination temperature on electrochemical performance of niobium oxides/carbon composites
Get PDFOrthorhombic niobium pentoxide (T-Nb2O5) possesses an intercalation pseudocapacitive behavior, which is a promising candidate of high-rate anodes for Li-ion capacitors. However, its low electric conductivity hinders the realization of this property. In our study, niobium oxides/carbon composites were prepared by calcinating a niobium peroxo-PAA complex (NbPAA) precursor to improve the electric conductivity. It has been found that the calcination temperature played an important role on the chemical compositions of obtained composites. A reduction phenomenon of niobium oxides by carbon was observed at high temperatures. At the medium temperature of 900 °C, the sample was composed of T-Nb2O5, monoclinic Nb2O5 (M-Nb2O5), amorphous carbon and niobium dioxide (NbO2). Due to the high conductivity of carbon, semi-conductivity of NbO2, and high specific capacity of M-Nb2O5, this sample exhibits a good specific capacity of 142 mAh g−1 (0.25 C) and a high-rate capability (capacity retention of 33.1%, 0.25 C to 25 C). It could be used as one of high-rate anodes for Li-ion capacitors. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: LTT20005, RP/CPS/2020/005Ministry of Education, Youth, and Sports, Czech Republic INTER-EXCELLENCE program [LTT20005, RP/CPS/2020/005