22 (2016) Scientific papers, Series A
Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/75385
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Článek Otevřený přístup peer-reviewedpublished The quality of fruit bars and crackers designated for the raw food vegan diet(University of Pardubice, 2016) Červenka, Libor; Brožková, Iveta; Fišerová Tereza, /Fruit bars and crackers designated for the raw vegan diet were evaluated with regard to the microbial quality, the presence of antioxidants (phenolics, flavonoids, and condensed tannins), and antioxidant properties. Since these products had been subjected to air drying up at 42 °C, the oxidation state of the fat (peroxide and thiobarbituric values) and the activity of superoxide dismutase and catalase was determined. In general, the samples were considered to be of good microbial quality, high antioxidant content, and capacity. As found out, the drying process did not alter the lipid oxidation and kept the activity of catalase constant in finished products.Článek Otevřený přístup peer-reviewedpublished Quercetin or glycine reaction products with acrylamide: A quantative approach to acrylamide detection using a pencil graphite electrode(University of Pardubice, 2016) Žabčíková, Simona; Kučerová, Petra; Červenka, LiborIn this article, the equimolar mixtures of acrylamide (AAm) and quercetin or glycine in aqueous solution at different pH, and after heating (100 °C for 60 min) have been studied. (Bare) pencil graphite electrode (PGE) in combination with square wave voltammetry were applied to the qualitative identification of the products. An interaction of AAm and quercetin at pH 2.0 resulted in the increase of reduction current at +128 mV, and an additional shift to +140 mV before and after heat treatment, respectively. PGE gave rise to only response for heat-treated AA/glycine mixture at pH 2.0, showing a higher oxidation current at positive potential and a higher reduction current at negative potential. In neutral media, two oxidation peaks were observed for heated AAm/glycine mixture. Theoretical considerations have been proposed.Článek Otevřený přístup peer-reviewedpublished Effect of harvesting and processing of stinging nettle on the antioxidant capacity of its infusions(University of Pardubice, 2016) Česlová, Lenka; Šilarová, Petra; Fischer, JanThe antioxidant properties of different matrices can be determined using various methods. In this work, two spectrophotometric methods based on the scavenging activity of the radicals DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2’- azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) were used together with a spectrophotometric method based on the ferric reduction power of phenolic compounds. The results obtained using all three methods were compared and discussed for infusions prepared from different parts of stinging nettle (Urtica dioica L.). The relation with the time of harvest and location of grow were also examined. Finally, the antioxidant capacity of all the studied nettle infusions were correlated with the total phenolic content determined using Folin–Ciocalteu reagent.Článek Otevřený přístup peer-reviewedpublished Characterization of α-tocopherol extraction into a selected carbon paste binder(University of Pardubice, 2016) Sýs, Milan; Vytřas, KarelAn extraction of "-tocopherol from different water-ethanolic mixtures into a commonly used paste binder was studied by ultraviolet spectrometry and anodic square wave voltammetry. It has been observed that distribution of the "-tocopherol between two immiscible phases is controlled by equilibrium constant that is significantly affected by the amount of organic solvent present in the aqueous phase. Moreover, it is evident that extraction of some biologically active compounds into the carbon paste could be used as the accumulation step within the extractive stripping voltammetric procedure to improve the sensitivity of their appropriate electroanalytical determination.Článek Otevřený přístup peer-reviewedpublished Attractive applications of less noble metal ions in stripping voltammetry at metal film electrodes(University of Pardubice, 2016) Vytřas, Karel; Tyszczuk-Rotko, Katarzyna; Metelka, Radovan; Ashrafi, Amir M.An overview is dished up to show how the presence of a less noble metal ion in the samples subjected to electroanalytical measurements may sometimes lead to a positive effect on determinations of some analytes at the trace concentration level. First, an unexpected behaviour of Sb-based electrodes is mentioned allowing one its application also in the anodic potential range. A role of less noble metals is documented on the stripping voltammetric determination of mercury(II) or bismuth(III) at antimony film-coated carbon paste electrodes, where an apparent catalytic effect caused by the presence of cadmium(II) was observed offering a significant improvement of the analytical signal for both the cations. This phenomenon was attributed to the formation of intermetallic compounds during the electrolytic accumulation at the electrode surface. Very recently, a new approach was reported based on the preparation of metal film electrodes that utilize the combination of ex situ and/or in situ plating methods and the use of reversibly deposited mediator. By plating the metal film onto the surface of glassy carbon electrode together with zinc acting as mediator metal, followed by its subsequent oxidation and further deposition of the metal of interest, a higher surface coverage of the electrode with metal particles could be achieved. Application of the newly developed technique was demonstrated on the determination of nickel(II) at a lead film electrode with the aid of adsorptive stripping voltammetry, as well as on the determination of tin(IV) at a bismuth film electrode when using square-wave anodic stripping voltammetry.Článek Otevřený přístup peer-reviewedpublished Determination of branched chain fatty acids in plasma of type 2 diabetics(University of Pardubice, 2016) Laštovička, Petr; Čermák, Tomáš; Hájek, Filip; Líbalová, Martina; Nováková Mužáková, Vladimíra; Skalický, Jiří; Čegan, AlexanderInsulin resistance in type 2 diabetic patients reduces activation of PPAR, which may lead to accumulation of branched-chain fatty acids, as well as saturated fatty acids, when natural sources of these fatty acids are dairy products. The aim of our study was to verify whether or not the accumulation of the branched chain fatty acids takes place in type 2 diabetes and, if so, to specify the corresponding lipid fraction. Totally 23 anonymised plasma samples of type 2 diabetic patients had been collected and subsequently divided by glycosidic haemoglobin levels into two groups of 11 compensated and 12 decompensated; the plasma of 10 healthy blood donors being further processed. At first, the samples were divided into particular lipid classes using thin layer chromatography. Then, we set the content of individual fatty acids in all lipid classes using gas chromatography. The results were calculated and evaluated statistically by applying the SigmaStat 3.5 program. It has been found that the most abundant branched chain fatty acid is 14-methylhexadecanoic acid as statistically significant increase of this acid was found in both compensated diabetics (p # 0.001) and decompensated ones (p # 0.001) in comparison with controls. The 14-methylhexadecanoic acid was ascertained in the diacylglycerol fraction, as well as in free fatty acid fraction of the compensated (p = 0.008) and decompensated (p = 0.007) diabetics. Furthermore, an increase in the content of branched-chain fatty acids in diabetic patients has been proved. An accumulation of these substances in diabetics thus raises a question on their actual effect on the human organism.Článek Otevřený přístup peer-reviewedpublished Release kinetics of tramadol hydrochloride from solid drug formulations(University of Pardubice, 2016) Myslíková, Kateřina; Komersová, Alena; Lochař, VáclavThe aim of this paper is to present the use of a reaction and a dissolution kinetic approach for evaluating the dissolution profile of a drug. As model substances, two controlled-release formulations (with different type of matrix) with tramadol hydrochloride were chosen. Release kinetics of tramadol hydrochloride was studied at isothermal conditions (37 °C) and at different pH values for media used for dissolution. The dissolution profiles obtained by using HPLC with UV detection were fitted by the first-order kinetic model, Korsmeyer–Peppas, Higuchi, and Weibull models. The main results of regression analysis were the determination of the first-order release rate constant (k1), the release exponent (n) from Korsmeyer–Peppas model, Higuchi constant (KH), and the parameters of Weibull model (b, λ).Článek Otevřený přístup peer-reviewedpublished Activity and selectivity of Mg-Fe mixed oxides in the aldol condensation of furfural(University of Pardubice, 2016) Kocík, Jaroslav; Kikhtyanin, Oleg; Tomášová, Adéla; Smoláková, Lucie; Hájek, Petr; Čapek, LiborThe aim of this work has been to compare the activity and selectivity of Mg-Fe mixed oxides in the aldol condensation of furfural with that of previously studied Mg-Al mixed oxides. Mg-Fe mixed oxides were prepared by thermal pre-treatment of hydrotalcites with a Mg/Fe molar ratio from 1.1 to 7.6. Structural and textural properties of Mg-Fe mixed oxides were analysed by using of XRD and N2- adsorption. It was found that Mg-Fe mixed oxides exhibited lower conversion of furfural in contrast to the Mg-Al mixed oxides, but being more selective to 4-(2- furyl)-3-buten-2-one (FAc). The difference in the conversion of furfural was relatively low among the Mg-Fe mixed oxides with the Mg/Fe molar ratio in the range of 1.1-5.5.Článek Otevřený přístup peer-reviewedpublished Application of new types of the sequestering agents to colourise cotton with the reactive dyes in hard water(University of Pardubice, 2016) Bayerová, Petra; Hajdová, Zuzana; Burgert, Ladislav; Černý, MichalIn this work, a possibility to use the sequestering agents in the development stage for colourising in hard water was investigated. To treat a cotton material in this way, the reactive dyes of vinylsulfone type were chosen. The quality of coloration was evaluated using the degree of exhaustion of the dye bath together with an objective color measurement.Článek Otevřený přístup peer-reviewedpublished Acrylic coatings modification by reactive nanogels prepared by emulsion polymerisation: A study(University of Pardubice, 2016) Machotová, Jana; Šňupárek, Jaromír; Prokůpek, Luboš; Večeřa, MiroslavIn this paper, the influence of hydroxyl-functionalised acrylic nanogels incorporated into solvent-borne and water-borne acrylic binder system on the properties of coating films is described. Our approach has been to show the usefulness of prepared reactive nanogels as network precursors. As found out, the application of nanogels did not affect the surface appearance and the transparency of solvent-borne thermosetting coatings. Moreover, the presence of nanogel network precursors accelerated the cure at ambient temperature, thus improving the final hardness of coatings.