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Marina Engelmann, Hannes Schmidt, Javid Safarov, Júrgen Nocke and Egon Hassel

., Santos, F. J. V., Santos, M. S. C. S., Lopes, J. N. C., Veiga, H. I. M., Macatrão, M., Esperança, J. M. S. S., Marques, C. S., Rebelo, L. P. N., Afonso, C. A. M. (2010) Fluid Phase Equilibria 294: 157-179. Rogers, R. D., Seddon, K. R. (eds.): (2003) Ionic Liquids as Green Solvents: Progress and Prospects. ACS Symposium Series. ACS, Washington. Safarov, J., El-Awady, W. A., Shahverdiyev, A., Hassel, E. (2011) Journal of Chemical Engineering Data 56: 106-112. Safarov, J. T. (2003) The Journal

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Michal Malček, Lukáš Bučinský and Stanislav Biskupič

(1996) Phys. Rev. Lett. 77: 3865. Rimarčík J, Punyain K, Lukeš V, Klein E, Dvoranová D, Kelterer AM, Milata V, Lietava J, Brezová V (2011) J. Mol. Struct. 994: 61. Rimarčík J, Punyain K, Lukeš V, Klein E, Kelterer AM, Milata V, Brezová V (2010) ACS 3: 20 Stephens PJ, Devlin FJ, Chabalowski CF, Frisch MJ (1994) J. Phys. Chem. 98: 11623. Zhao Y, Truhlar DG (2006) J. Chem. Phys. 125: 194101.

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Rastislav Monošík, Miroslav Streďanský and Ernest Šturdík

JF (2010) Anal. Chem. 82: 3118-3123. Mani V, Chikkaveeraiah BV, Patel V, Gutkind JS, Rusling JF (2009) ACS Nano 3: 585-594. McNaught AD, Wilkinson A (1997) IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Blackwell Scientific Publications, Oxford. Mieliauskiene R, Nistor M, Laurinavicius V, Csoregi E (2006) Sensor Actuat. B-Chem. 113: 671-676. Mizutani F, Hirata Y, Yabuki S, Iijima S (2003) Senor Actuat. B-Chem. 91: 195

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František Kreps, Štefan Schmidt, Lenka Vrbiková, Lucia Szeifová, Lenka Tmáková and Stanislav Sekretár

Influence of storage and microwave heating on stability of soya spread lipids with linseed content

We have chosen to experiment with soya spreads containing linseeds, which enrich the spreads with essential fatty acids and valuable related substances. The soya spreads with linseeds represent an ideal combination for nutritionally valuable foods with health benefits. In this work we examined the influence of microwave heating and storage on stability of linseed oil and soya spread lipids. Industrially produced soya spreads (S1) with addition of 5, 7 and 10 % linseeds and linseed oil were stored without a protective atmosphere in refrigerator at 5 °C. The lipids of commercial soya spreads (S2) enriched with 2, 5 and 10 % ground linseeds and soya spread lipids (S2) without linseeds were microwave-heated. The data obtained from experiments have shown that the storing of linseed oil for 30 days in refrigerator has caused excess of the maximum acceptable peroxide value (Food Codex of SR). Microwave-heated lipids from commercial soya spreads (S2) enriched with 2 % ground linseeds have the best result of stability and protective factor, compared with lipids from 5 and 10 % linseeds enriching soya spreads (S2). After the 5, 10 and 20 min of microwave heating, the lipids of soya spread (S2) enriched with 2 % ground linseeds have the protective factor 1.02, 1.15 and 1.43 respectively, compared with lipids from soya spread (S2) without linseeds. The microwave heating for 5 min has been accompanied by a decreasing of hydroperoxides and by formation of secondary oxidation products.

Open access

Martina Danihelová, Jana Viskupičová and Ernest Šturdík

Lipophilization of flavonoids for their food, therapeutic and cosmetic applications

Flavonoids represent large group of plant pigments. These polyphenolic compounds may be found in the nature as active components of fruits, vegetables and other plants and derived products. Due to established biological effects they are attractive substances for many areas of human life. Many flavonoids are nowadays used in pharmaceutical, cosmetic and food preparations. Their practical applications are in most cases limited by low solubility and stability in lipophilic media. Chemical or enzymatic lipophilization of flavonoid skeleton may not only increase their solubility and stability in lipophilic environment but also their biological properties. This review summarizes current knowledge in this field.

Open access

Vít Samohýl, Ivan Samohýl and Petr Voňka

Partial Pressures in Thermodynamics of Classical Fluid Mixtures

In the rational thermodynamics of most usual nonequilibrium "classical" fluid mixtures it has been proposed the "thermodynamic" partial pressure which generalize traditional definitions and merge together in an ideal gas mixture. In this paper, these thermodynamic partial pressures are calculated for a (real) gas mixture of methane-ethane-carbon dioxide and a liquid mixture of lithium hydroxide in water. The results are compared with those obtained using the classical formulations of partial pressures calculated in these mixtures as well.

Open access

Lenka Rottmannová, Adam Vagánek, Ján Rimarčík, Vladimír Lukeš and Erik Klein

S—H Bond Dissociation Enthalpies in para- and meta-Substituted Thiophenols: Correlation with Thiophenolic C—S Bond Length

For mono-substituted anilines, phenols, and thiophenols it has been found that N—H, O—H and S—H bond dissociation enthalpies (BDE) depend on Hammett constants approximately linearly. For substituents placed in meta position, linearity of found dependences is usually considerably worse in comparison to para-substituted molecules. Therefore, their applicability for prediction of changes in BDE using substituent Hammett constant may be limited. In this work, we have found that the length of thiophenolic C—S bond, R(C—S), or its shortening after hydrogen atom abstraction, ΔR(C—S), represent suitable descriptors of substituent induced changes in S—H BDE. For fifteen studied meta-substituted thiophenols, these geometry descriptors correlate with S—H BDEs considerably better than Hammett constants.

Open access

Viktor Milata, Ladislav Reinprecht and Juraj Kizlink

Synthesis and antifungal efficacy of 1,3,5-triazines

1,3,5-triazines with tree identical groups: benzotriazol-1/2-yl, imidazol-1-yl, pyrazolyl-1-yl, 3,5-dimethylpyrazolyl-1-yl, 4,5-diphenylimidazol-1-yl, benzimidazolyl-1-yl, 2-methylbenzimidazolyl-1-yl, or 2-phenylbenzimidazolyl-1-yl were synthesised. Their biological activity against wood-destroying fungi Serpula lacrymans, Coniophora puteana and Trametes versicolor was tested by the impregnated filter paper method. S. lacrymans occurred as the most sensitive fungus (from the 3 fungi) in the presence of triazines. Triazines having three imidazol or three 4,5-diphenylimidazol groups were a slightly more effective than others. However, their efficacy in comparison with the commercial fungicides Tebuconazole and IPBC was insufficient.

Open access

Anna Luptáková, Karol Munka and Ján Derco

Increasing of drinking water quality at real water treatment plant by recarbonization process

According to the World Health Organization, chemical and microbial contaminants in drinking water will continue in the interest of suppliers of drinking water. The review establishment of new knowledge for drinking water including the potential benefits of the mineral content is necessary. The paper is focused on an assessment of the quality of water from surface source for drinking water preparation and quality of drinking water produced at the real plant. The lab-scale verification of water recarbonization with lime and carbon dioxide was chosen based on the results of full scale plant data analysis. Recarbonization tests were carried out with the raw water and the impact of recarbonization on coagulation process at different coagulant doses was studied. The results show that water recarbonization had adverse influence on the water treatment processes.

Open access

Jan Balej

Solubility in the System (NH4)2S2O8—NH3—H2O and Mean Activity Coefficients of Saturated Solutions of (NH4)2S2O8

The solubility data of ammonium peroxodisulfate in aqueous ammonia solutions at 15.5 °C have been evaluated using the relative activity coefficient expansion. Using the known value of the mean activity coefficient of saturated solution of ammonium peroxodisulfate in pure water, values of the mean activity coefficients of this salt in the saturated solutions of the given system have been calculated.