Digitální knihovnaUPCE
 

17 (2011) Scientific papers, Series A

Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/75335

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201122

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Nyní se zobrazuje 1 - 10 z 22
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Analysis of ethoxylated nonylphenols by combination of HPLC and CZE
    (University of Pardubice, 2011) Fischer, Jan; Česla, Petr; Samková, Libuše
    The separation of samples of ethoxylated nonylphenol type surfactants by twodimensional method combining liquid chromatography with capillary zone electrophoresis has been studied. In the first part of the work, separation conditions using reversed-phase liquid chromatography with isocratic elution were optimized. Thus six different stationary phases were compared to provide highest resolution of ethoxylated nonylphenol surfactants with various degrees of ethoxylation in water/methanol and water/acetonitrile mobile phases. The separation of nonylphenol branch isomers was carried out using capillary zone electrophoresis in non-coated and poly(acryl amide) coated capillaries employing solvofobic interaction approach in background electrolyte containing sodium dodecyl sulfate and acetonitrile. Finally, nonionic surfactants were analyzed using combination of optimized methods of liquid chromatography and capillary zone electrophoresis in off-line automated two-dimensional system.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Determination of serum creatinine in selected groups of patients by means of HPLC with UV detection – comparison with Jaffé and enzymatic assays
    (University of Pardubice, 2011) Štramová, Xenie; Kanďár, Roman
    A reversed-phase high-performance liquid chromatography method for the determination of creatinine in human serum samples has been developed. Results from measurements of by a high-performance liquid chromatography on 232 serum samples were compared with enzymatic and Jaffé methods. The serum samples were deproteinized with ethanol. For the separation, a column MAG 1, 250 mm x 4.6 mm, Labiospher PSI 100 C18, 5 :m, was used. The mixture of ethanol and 25 mmol l–1 sodium hydrogenphosphate (3:97 v/v), pH 6.5 was used as a mobile phase. The analytical performance of this method is satisfactory: the intra-assay and inter-assay coefficients of variation were below 6 %. Quantitative recoveries of spiked serum samples were between 101.8 and 106.0 %. The limit of quantification was 10.0 :mol l–1. The results obtained by chromatographic method correlated well with Jaffé assays. Enzymatic method gave at average significantly higher values depending on a group of patients. The presented high-performance liquid chromatographic assay is useful for the analysis of samples where the classical Jaffé or enzymatic methods do not give reliable results and can be a candidate for reference method.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    In vitro antimicrobial activities of anethole, carvacrol, cinnamon bark oil, eugenol, guaiazulene and thymol against G streptococci
    (University of Pardubice, 2011) Kusáková, Eva; Mosio, Petra
    The present study describes the antimicrobial activity of various natural substances against group G streptococci. A total of 50 strains of group G streptococci was included in this study. The minimum bactericidal concentrations of 6 substances — anethole, eugenol, guaiazulene, carvacrol, cinnamon bark oil from Cinnamomum zeylanicum and thymol were obtained by the broth microdilution method. The substances were extended either directly in brain heart infusion broth or in 24 % ethanol. Carvacrol was found to be the most effective substance with the highest antimicrobial activity, which inhibited the growth of 90 % of group G streptococci strains at the concentration of 236.7 :g ml–1. The minimum bactericidal concentrations of eugenol, oil from the bark of Cinnamomum zeylanicum, and thymol were 1000 :g ml–1. Anethole and guaiazulene were the least effective natural substances in our study.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Assessment of glutathione reductase inhibition
    (University of Pardubice, 2011) Nýdlová, Erika; Roušar, Tomáš
    Glutathione reductase is a crucial enzyme for maintaining of intracellular glutathione levels. This enzyme catalyzes the NADPH-dependent reduction of glutathione disulfide to the reduced form (GSH). The aim of our study was to estimate a possible inhibitory effect on glutathione reductase activity in the presence of two substances that cause glutathione depletion - ethacrynic acid and diethyl maleate. We also tested glutathione as a possible inhibitor. The experiments were performed with yeast glutathione reductase. GR activity was determined using spectrophotometric method based on measurement of absorbance decline (8 = 340 nm) due to oxidation of NADPH. We found that dose dependent inhibition of glutathione reductase occurred in the presence of ethacrynic acid; the enzyme activity was inhibited by 19 % and 29 % in the presence of 500 :M and 1000 :M ethacrynic acid, respectively. We also found that although diethyl maleate is able to induce deep glutathione depletion in the cell, it does not affect the GR activity. On the other hand, we found dose dependent inhibitory effect through reduced glutathione — the presence of 10 mM GSH caused a decrease in enzyme activity by 60 %. We conclude that our finding of inhibitory effect in the presence of glutathione is of great importance since the GSH levels are very high in the cells. It follows that glutathione reductase possesses a substantial reserve in enzyme activity that could be used in oxidative stress conditions.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Aromatic diazo and azo compounds LXIV. New amino compounds and new azo dyes based on naphto[2,1-d]oxazole
    (University of Pardubice, 2011) Mužík, Ferdinand
    The paper is focused on innovation of a chemical process leading to new amino compounds of structural formula I and their application to preparation of new azo dyes II. The procedure of preparation of the key derivative is presented. This derivative is aminonaphthoxazoledisulfonic acid III, which is used in syntheses of a number of azo dyes belonging to various technological and application categories. In this way, a chemically new class of azo dyes, containing the naphtho[2,1-d]oxazole skeleton in their molecules, was established.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Kinetic processes in Te-Se glasses
    (University of Pardubice, 2011) Svoboda, Roman; Honcová, Pavla; Málek, Jiří
    Structural relaxation kinetics and crystallization kinetics of chosen compositions from the Se-Te glassy system were studied under non-isothermal conditions by using differential scanning calorimetry in dependence on particle size. The purpose of this contribution is to demonstrate the extent of information accessible by the present-day kinetic analysis provided by the differential scanning calorimetry and to suggest its importance and merit for the development of new high-tech PCM materials. Enthalpic relaxation was described on the basis of Tool–Narayanaswamy–Moynihan model. Single set of TNM parameters was obtained from the curve-fitting procedure for each studied glass. A comparison with our previous measurements on a-Se was made and the development of particular TNM parameters with increasing Te content was discussed in terms of changes in molecular structure of the material. The curve-fitting results were further verified by several independent non-fitting methods. The crystallization kinetics was described in terms of the nucleation-growth Johnson–Mehl–Avrami model. Complexity of the crystallization process was in this case represented by very closely overlapping consecutive competing surface and bulk nucleation-growth mechanisms. Mutual interactions of both mechanisms as well as all other observed effects were explained in terms of thermal gradients, surface crystallization centres arising from the sample preparation treatments and changing amount of volume nuclei originating from the combination of prenucleation period and the very glass preparation phase. Advanced error analysis was performed for each step of the kinetic study. A new criterion for quick determination of the dominating crystallization mechanism — surface or bulk — was introduced.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Kinetic study of dehydration of calcium oxalate trihydrate
    (University of Pardubice, 2011) Honcová, Pavla; Málek, Jiří; Vařečka, Jan; Sádovská, Galina
    The dehydration of calcium oxalate trihydrate was studied by using DSC method. The dehydration proceeds in two steps where the first two molecules of water dehydrate around 100 °C and consequently the last molecule of water dehydrates at a temperature around 200 °C. The kinetic analysis was done and the apparent activation energy, pre-exponential factor and kinetic exponents of autocatalytical model were evaluated for both effects.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Testing of corrosive-inhibitive properties of zinc orthophosphate doped with lanthanum orthophosphate
    (University of Pardubice, 2011) Myšková, Veronika; Bělina, Petr; Šulcová, Petra
    This paper deals with the study of corrosion-inhibition properties of commercially used pigment Zn3(PO4)2 after the modification with lanthanum orthophosphate in various molar ratios. The system Zn3(PO4)2/LaPO4 was prepared in one step synthesis by crystallization method. Individual pigments were examined in the synthetic-based paint and water-based paint. The samples were exposed to influences in the condensation chamber, atmosphere of 100 % humidity and to the content of 0.2 a 1 dm3 SO2. The prepared pigments were evaluated from the viewpoint of the degree of rusting, the blistering, degree of cracking, corrosion in the surroundings of cut and corrosion in the surface. The evaluation, which took place in the comparison with commercially available samples and laboratory prepared Zn3(PO4)2, show very good efficiency for the protection of metallic materials.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Synthesis and thermodynamic properties of amorphous calcium phosphate
    (University of Pardubice, 2011) Kohutová, Anna; Pilný, Petr; Honcová, Pavla; Svoboda, Ladislav
    The formation of amorphous calcium phosphate (ACP) was studied in the context of urinary stones formation. Processes of ACP precipitation were observed in simulated medium: in aqueous solutions of potassium chloride and artificial urine (SRAU) at the ionic strength of 0.3 mol dm–3. Amorphous structure of calcium phosphate was verified by X-ray diffraction analysis and Raman spectroscopy. Thermochemical study of ACP precipitation was investigated by using the isoperibolic reaction twin calorimeter. The experiments were carried out at the initial concentrations of ACP in the range from 6 to 14 mmol dm–3 for KCl solution and 6-16 mmol dm–3 for SRAU. The ACP precipitation was performed by reaction of Ca2+ and ions with Ca:P molar ratio close to 1.5 at the temperatures of 298.15 K and 310.15 K. The molar enthalpy of ACP formation was calculated by use of ACP solubility which was determined in this work. Molar enthalpies of ACP formation, )Hm, are 29.8 ± 0.9 kJ mol–1 at 298.15 K and 36.3 ± 0.9 kJ mol–1 at 310.15 K in KCl solution, and )Hm 298.15 = 35.4 ± 1.3 kJ mol-1 and )Hm 310.15 = 41.6 ± 1.5 kJ mol–1 in SRAU.
  • Náhled
    ČlánekOtevřený přístuppeer-reviewedpublished
    Screens of offset prints and ink content in recycling process
    (University of Pardubice, 2011) Bolanča Mirković, Ivana; Majnarić, Igor; Bolanča, Zdenka; Modrić, Mara
    The influence of the screen of the offset colour prints on the recycling effectiveness has been investigated in this work. The printing form contained four parts. Two parts were realized by the amplitude modulated screening with the screen ruling L 60 lines cm–1 screen and 80 lines cm–1 screen, while the other two were realized by frequency modulated screening (diameter of the individual dot 20 :m and 40 :m). Gloss and mat fine art paper and paper made from the recycled raw materials were used for the preparation of samples. On the basis of the obtained results it can be concluded that the dirt spot number and the area are greater when the print made with AM screening was used for recycling in relation to the print made with FM screenings. Number of the particles formed in the disintegration process of prints has been explained from the aspect of the printing surface coverage. It was proved that in that combination the coating of the printing substrate is an essential factor for the effectiveness of the deinking flotation. The number and the area of the dirt spots as a function of their classes are depleted according to the exponential function used as a fit in one model.