23 (2017) Scientific papers, Series A
Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/75253
Procházet
Článekpeer-reviewedpublisher's version Otevřený přístup Rheological properties of the polyurethane adhesives(University of Pardubice, 2017) Palarczyková, Zuzana; Šiška, Bedřich; Machač, IvanIn this contribution, the results of measurements are presented concerning rheological and mechanical properties of polyurethane adhesives used in the automotive industry. The work is focused on the determination of rheological characteristics of the individual components of polymeric adhesives tested and on rheological and mechanical properties of the adhesives in the hardening process. Experiments were performed with one type of single-component adhesive and three types of two-component adhesives. All the components of PUR adhesives tested were viscoplastic with a certain degree of yield stress. The respective flow curves showed a shear-thinning and thixotropic behaviour; the results of oscillatory tests demonstrating that elastic behaviour dominated for all adhesive components. The elasticity of an adhesive evidently depended on their mixing ratio. Finally, it has been found out that adhesive gelation points measured in the hardening process could be detected much faster at a higher temperature than at a lower one.Článekpeer-reviewedpublisher's version Otevřený přístup 30 years with carbon paste electrodes at the University of Pardubice(University of Pardubice, 2017) Švancara, Ivan; Metelka, Radovan; Mikysek, Tomáš; Vytřas, KarelIn this review (with 425 Refs), three decades of the electrochemistry and electroanalysis with carbon paste electrodes characterising the research activities of the electroanalytical group at the University of Pardubice (EAG UPa) are summarised, when presenting all the achievements and, where applicable, also highlighting research outputs throughout the time. In more detail, reminded are the very beginnings in the mid-1980s and the early era at the University of Chemical Technology. The article contains the complete list of publications plus a great majority of conference presentations associated with the field and having been prepared by the EAG UPa in the period 1987-2016.Článekpeer-reviewedpublisher's version Otevřený přístup Extended release tablets containing co-processed dry binders and tramadol hydrochloride – determination of the content uniformity(University of Pardubice, 2017) Myslíková, Kateřina; Komersová, Alena; Lochař, Václav; Mužíková, JitkaAn automated method for the extended release tablet processing and determination of tramadol hydrochloride in matrix tablets containing coprocessed dry binders has been developed by using a bench-top robotic system connected with HPLC system. The automated operations include (i) disintegration steps of the dosage form, (ii) homogenisation, (iii) setting time, (iv) filtration, (v) dilution, and (vi) injection of a sample into the HPLC vials or chromatographic system. The method developed has been optimized and validated; recoveries of spike tests being found in the range of 97.8-99.6 %. The relative standard deviation representing the precision of the method was 1.02 % for tramadol hydrochloride in tablets with DisintequikTM MCC 25 and 1.15 % for tramadol hydrochloride in tablets with Prosolv® SMCC 90. The validated method was applied to the determination of the target substance in samples of two commercial pharmaceutical formulations: Tralgit SR 100 and Tramadol Retard Actavis 100 mg.Článekpeer-reviewedpublisher's version Otevřený přístup A zwitterionic (poly)methacrylate monolitic capillary column with dual HILIC – reversed-phase mechanism for uni- and two-dimensional HPLC(University of Pardubice, 2017) Staňková, Magda; Jandera, PavelSulfobetaine zwitterionic monolithic columns were synthesized by in-situ polymerization (in fused silica capillaries) of a N,N-dimethyl-N-metacryloxyethyl- N-(3-sulfopropyl) ammonium betaine (MEDSA) functional monomer in combination with different cross-linking monomers. From among the ten crosslinkers tested, bisphenol A glycerolate dimethacrylate provides monolithic capillary columns with best chromatographic efficiency (60 000-70 000 theoretical plates per meter). The respective columns show excellent column-tocolumn reproducibility of pore morphology, separation selectivity, good permeability and low mass transfer resistance, so that being suitable for fast and selective separation of various samples. Monolithic sulfobetaine polymethacrylate (BIGDMA-MEDSA) micro-columns designed in our laboratory exhibit a dual retention mechanism, in acetonitrile-rich mobile phase, polar (hydrophilic) interactions control the retention (HILIC separation mode), whereas in more aqueous mobile phases the column shows essentially non-polar with a major role of hydrophobic interactions properties (reversed-phase, RP mode). The dual-mode retention mechanism was investigated and applied to the HILIC and reversedphase HPLC separations of barbiturates, sulfonamides, nucleobases, nucleosides, phenolic, and other carboxylic acids, polyphenols, flavonoids plus other lowmolecular compounds. The separation selectivities in the HILIC and RP dimensions are highly complementary to each other, so that a zwitterionic sulfobetaine polymethacrylate micro-column can be used in the first dimension of two-dimensional LC in alternating RP and HILIC modes, coupled with a short (3- 5 cm) alkyl-bonded core-shell or silica-based monolithic column in the second dimension, for HILIC×RP and RP×RP comprehensive two-dimensional separations. During the HILIC×RP period, a programme with the decreasing acetonitrile gradient is used for separation in the first dimension, so that at the end of the gradient the polymeric monolithic micro-column is equilibrated with a highly aqueous mobile phase and is ready for repeated sample injection, in this case, for separation under reversed-phase gradient conditions with the increasing concentration of acetonitrile in the first dimension.Článekpeer-reviewed Otevřený přístup Laser induced breakdown spectrometry for quantitative analysis of Cd in artificial sweat leachate of jewellery(University of Pardubice, 2017) Zvolská, Magdalena; Pouzar, Miloslav; Černohorský, Tomáš; Jarolím, OldřichA new method has been developed for the determination of cadmium in artificial sweat leachate using laser induced breakdown spectrometry (LIBS). Small volume of liquid samples could be applied onto the solid carrier, dried under the IR lamp, and subsequently analysed by the LIBS device. For calibration, two series of standard solutions of artificial sweat were prepared: alkaline (pH 8) and acidic (pH 5.5). The known volumes of the Cd standard (with concentration of 1 ± 0.001 g l–1) were added into the samples of artificial sweat; calibration standards prepared ranging from 0-40 mg l–1 for acidic and 0-30 mg l–1 for alkaline sweat. To optimize the LIBS measurements, the regression parameters (R2, AIC, MEP) were the criteria of choice. For our purposes, three cadmium lines at wavelengths 214.44 nm, 226.50 nm, and 228.80 nm were monitored. In model solutions, the method developed has provided the limits of detection (LODs) of 0.08 mg l–1 for acidic and of 0.06 mg l–1 for alkaline sweat. The optimized method could then be used for the determination of Cd in artificial sweat leachates of jewellery samples, when the values obtained were in good agreement with the results from the reference analysis by ICP-OES. The proposed method is fast, simple, and requiring only minimal volume of samples. For analysis of leachate of jewellery, fabrics or products of daily consumption, this approach employing LIBS can be an interesting alternative to commonly used techniques, such as ICP OES or AAS.Článekpeer-reviewedpublisher's version Otevřený přístup Effect of surface treatment of pigment particles with polyparaphenylene-diamine phosphate on their corrosion inhibiting properties in organic coatings(University of Pardubice, 2017) Hájková, Tereza; Kalendová, Andréa; Kohl, Miroslav; Antošová, BarboraThe main goal of this work was to investigate the corrosion inhibiting and physical properties of organic coatings containing pigments whose surface had been modified with a layer of a conductive polymer in comparison with the untreated pigments. Four perovskite-based pigments, viz. CaTiO3, SrTiO3, CaMnO3 and SrMnO3, were prepared by high-temperature calcination, and their surface modified with a layer of the conductive polymer poly(pphenylenediamine). This modification was achieved by oxidative polymerisation. The physico-chemical properties of the pigments were examined by XRD, XRF, and SEM. The composite pigments were used in coatings (paints) based on a solvent-type epoxy-ester resin. The pigment volume concentration (PVC) in the paints was 1 %, 5 %, 10 %, and 15 %. The paint films were subjected to physicomechanical tests and accelerated corrosion tests; the respective results being correlated with the pigment type and concentration and with the surface modification with poly(p-phenylenediamine) as a conductive polymer. The anticorrosion and mechanical properties of the paints have been compared to those of a reference paint containing zinc phosphite hydrate, a proven and established anticorrosion pigment.Článekpeer-reviewedpublisher's version Otevřený přístup Investigation of the structural and charge properties of a polyamide nanofiltration membrane(University of Pardubice, 2017) Wallace, Edwin; Cuhorka, Jiří; Mikulášek, PetrNanofiltration (NF) membrane had gained interest worldwide due to the excellent removal of contaminant(s) with lower energy consumption compared to reverse osmosis. NF is used for several environmental applications; for example, pharmaceutical and biotechnology, or desalination. The fundamental principle behind the separation mechanism of nanofiltration can be fully understood by defining the structural and charge properties of the membrane. In the present work, a polyamide thin-film composite NF membrane (AFC 30) was used for characterization of the structural and charge surface properties. The structural properties are the pore radius (rp) and the membrane thickness-to-porosity ratio ()x/Ak), respectively. The interpretation of values from the different uncharged solutes rejection allows one to determine the structural properties of AFC 30. This was done by using modelling of rejection of the uncharged solutes with the aid of the Donnan steric partitioning model (DSPM). In addition, the membrane was considered to be modelled as a bundle of cylindrical pores. It has been observed that the pore radius and thickness-to-porosity ratio from AFC 30 membrane are similar irrespective of the different uncharged solutes. The fixed charge density on the membrane surface was determined by experiments with sodium chloride at different concentrations. The data from such a sodium chloride experiment(s) were used to calculate the effective charge density (KX) by using the Spiegler–Kedem model together with a charge model called Teorell–Meyer–Sievers (TMS). Then, it has been revealed that the membrane charge depends solely on the salt concentration in the solution because of the ion adsorption onto the membrane surface. The reliance of the charge density of the NaCl concentration follows the well-known equation — Freundlich isotherm.Článekpeer-reviewedpublisher's version Otevřený přístup Eco-friendly sucrose and polyvinyl acetate-based polymeric systems(University of Pardubice, 2017) Puková, Kateřina; Machotová, Jana; Mikulášek, Petr; Rückerová, AdélaThis work is focused on the synthesis of aqueous polymeric dispersions based on polyvinyl acetate and sucrose formed by emulsion polymerization technique. These polymeric latexes can be used in the field of sustained release fertilizer encapsulation or as ecological paper glue with the subsequent biological disposal. The main objective of the work was to bond covalently sucrose into polyvinyl acetate ensuring the effective biodegradation of the respective polymer mainly in the soil environment. We have searched for an optimal ratio between the polymer and the simple sugar in the alkaline medium so that the resulting latex could exhibit good water solubility, sufficient bond strength, and the stability of atmospheric humidity. Using infrared spectroscopy, the process of binding sucrose into the polymer chain of vinyl acetate has been demonstrated.Článekpeer-reviewedpublisher's version Otevřený přístup The synthesis of Zn-Al hydrotalcites under different conditions and testing in aldol condensation(University of Pardubice, 2017) Hájek, Martin; Muck, Jáchym; Kozáček, Pavel; Kocík, Jaroslav; Lederer, Jaromír; Vávra, AlešThe Zn-Al hydrotalcites (materials with the layered structure) with constant molar ratio of Zn/Al 2:1 were synthesized by co-precipitation method under different reaction conditions, such as pH, the concentration of ions, temperature throughout co-precipitation, the intensity of stirring, etc. The mixed oxides were formed from hydrotalcites by calcination at 450 °C. All synthesized materials were characterized by X-ray diffraction, thermogravimetric analysis, and via the specific surface area. The influence of the synthesis conditions on the crystallite size and specific surface area were studied. The formation of hydrotalcites as well as mixed oxides was confirmed by X-ray diffraction. The mixed oxides chosen were rehydrated, which enabled to restore their layered structure. Both mixed oxides and rehydrated (mixed) oxides were tested in the aldol condensation of furfural, resulting in finding that the rehydration would decrease the conversion of furfural when using all the rehydrated mixed oxides.Článekpeer-reviewedpublisher's version Otevřený přístup Determination of selected fatty acids in dried blood spot by gas chromatography-flame ionization detection(University of Pardubice, 2017) Andrlová, Lenka; Řeháková, Zuzana; Kanďár, RomanWith the aim to minimize the amount of biological material needed for analysis, a new type of sample preparation has been used for the determination of the percentage content of fatty acids in human blood. The blood samples from the volunteers (n = 30) were processed in two ways, as a plasma and as dried blood spot (DBS) samples. The fatty acids were firstly derivatized into the respective esters and, subsequently, separated and detected using gas chromatography (GC) with a flame ionization detector (FID). The results obtained from the DBS sample analysis were compared with those obtained by the established method for the determination of fatty acids in plasma.Článekpeer-reviewedpublisher's version Otevřený přístup Preparation of zinc oxide nanoparticles for polymeric systems(University of Pardubice, 2017) Matysová, Edita; Cousy, Simon; Zelenka, Jiří; Svoboda, LadislavThe aim of the work was the synthesis of zinc oxide nanoparticles incorporated into water-based polymer systems together with assessment of their effect on the mechanical properties of the prepared nanocomposites. ZnO nanoparticles were prepared by basic precipitation of zinc salts in water. To ensure perfect compatibility with the polymeric systems and to control the particle size, the ZnO nanoparticle surface was modified by polymeric surfactants tailored for this purpose. ZnO particles were physically bonded to the water-based system via electrostatic interactions. All the composites have shown improved mechanical properties compared to the unmodified systems depending on the ZnO concentration in the water-based system.Článekpeer-reviewedpublisher's version Otevřený přístup Analysis of volatile organic compounds in rose petals using headspace solid-phase microextractor coupled to gas chromatography-mass spectroscopy(University of Pardubice, 2017) Eisner, Aleš; Surmová, Silvie; Bajer, Tomáš; Kosová, Tereza; Ventura, KarelHeadspace solid-phase microextraction coupled to gas chromatography and mass spectrometry (HS-SPME-GC/MS) has been optimised for the analysis of volatile compounds in six samples of rose petals (Rosa Mariyo, Rose Tara, Rosa Rhodos, Rosa Sudoku, Rosa Deep Purple, Rosa Tacazzi). Volatiles from roses were extracted using a SPME fibre by carrying out the subsequent separation and identification by comparison of their mass spectra with mass spectra libraries and retention indexes. Several factors influencing the SPME were taken into account; namely, extraction time, extraction temperature and the sample weight. The optimal parameters of the extraction of volatile compounds were obtained based on statistical evaluation; the most suitable conditions being the extraction time of 60 min., the extraction temperature of 90 °C and the sample weight of 0.7 g.Článekpeer-reviewedpublisher's version Otevřený přístup Primer or primer-free gluing: problems of adhesives in automotive industry(University of Pardubice, 2017) Prokůpek, Luboš; Večeřa, Miroslav; Machotová, JanaThe presented work aims at the comparison of physical and mechanical properties of commercially available black polyurethane adhesives designed for the glass bonding in automotive industry and at the assessment of adhesive systems with a primer. These adhesives require application and drying out of the appropriate polymer or a primer-free adhesive layer before bonding. UV stability is additionally measured in a view of the changing colours and mechanical properties.Článekpeer-reviewedpublisher's version Otevřený přístup Catalitic activity of Agaricus bisporus mushroom tyrosinase to acetaminophenon in the presence of L-proline(University of Pardubice, 2017) Sýs, Milan; Klikarová, Jitka; Česlová, Lenka; Vytřas, KarelSecondary reaction of amino acid L-proline with 4-acetamido-o-benzoquinone as a product of the enzymatic oxidation of acetaminophen mediated by mushroom tyrosinase isolated from Agaricus bisporus has been studied by amperometric detection in the batch injection analysis configuration and by ultraviolet-visible spectrophotometry. Actually, this scientific work is focused on finding out whether it would be possible to develop an indirect electrochemical method based on the amperometric biosensing suitable for monitoring of the L-proline in various honey samples. For optimum content of acetaminophen (100 :mol dm–3) and tyrosinase (3.33 :g cm–3), a satisfactory linear range from 0.1 to 0.5 mmol dm–3 L-proline was obtained for absorption maximum at 332 nm. However, it is necessary to mention that the indirect determination of L-proline by the amperometric tyrosinase biosensor still presents a challenge in the field of developing biological sensors for monitoring of this amino acid.Článekpeer-reviewedpublisher's version Otevřený přístup Flow of viscoelestic liquids through metal filter screens(University of Pardubice, 2017) Machač, Ivan; Šiška, BedřichThis article reports on the results of the pressure drop measurements in dependence on the liquid volume flow rate in the creeping flow of viscoelastic aqueous polymer solutions through woven metal screens. The respective experiments were performed in a plastic cell of 50 mm inner diameter in which the tested screen had been placed. In such measurements, the six types of screens of different weaving were examined in the flow of nine various polymer solutions. In the flow, a strong elastic pressure drop excess manifests itself. By analysing the experimental data, it has been verified that the pressure drop excess can be evaluated using the corrective Deborah number function.Článekpeer-reviewedpublisher's version Otevřený přístup Crystallization in Sb0.5Se99.5 glass studied under and without protective atmosphere(University of Pardubice, 2017) Honcová, Pavla; Pilný, Petr; Stehlík, Stanislav; Košťál, PetrThe crystallization in a Sb0.5Se99.5 glass was studied by DSC method. The manipulation with amorphous samples was done under the protective atmosphere of argon and also without this protection, by simply exposing to the air. The obtained DSC traces as well as their kinetic characterization have shown that the atmosphere during the manipulation with amorphous material has significant influence on its crystallization behaviour.