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Keve T. Kiss, Rolf Klee, Luc Ector and Éva Ács

References ÁCS É., SZABÓ K., KISS K. T., 2002: Nature conservation oriented algal biodiversity monitoring investigations in the main arm and some dead arms of the River Tisza I. Benthic diatoms. Limnological Reports 34, 111-120. ÁCS, É., SZABÓ, K., KISS, Á. K., TÓTH, B., ZÁRAY, GY., KISS, K. T., 2006: Investigation of epilithic algae on the River Danube from Germany to Hungary and the effect of a very dry year on the algae of the River Danube. Archiv für Hydrobiologie Suppl. Large Rivers 16, 389-417. ÁCS

Open access

Józef Bergier, Ewelina Niźnikowska, Barbara Bergier, Pongrac Acs, Ferdinand Salonna and Jan Junger

V, Holmen TL, Kurtze N, Cuypers K, Midthjell K. Reliability and validity of two frequently used self-administered physical activity questionnaires in adolescents. BMC Med Res Methodol. 2008;8:47; doi: 10.1186/1471-2288-8-47. 24. Janssen I, Leblanc A. Systematic review of the health benefits of physical activity and fitness in school-aged children and youth. Int J Behav Nutr Phys Act. 2010;7:40; doi: 10.1186/1479-5868-7-40. 25. Ács P, Hécz R, Paár D, Stocker M. Physical inactivity and the national economy in Hungary. Közgazdasági

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Ágnes Bolgovics, Éva Ács, Gábor Várbíró, Keve Tihamér Kiss, Balázs A. Lukács and Gábor Borics

assessments in Europe. Journal of Applied Phycology 10, 215-224. KISS, K. T., l987: Phytoplankton studies in the Szigetköz section of the Danube during l98l- l982. Archiv für Hydrobiologie, Algological Studies 47, 247-273. KISS, K. T., ÁCS, É., 2009: The algal fl ora of the River Bodrog. Thaiszia - Journal of Botany, Kosice 19, Suppl. 1, 99-124. KISS, K. T., GENKAL, S. I., 1996: Phytoplankton of the Danube’s reservoirs in September 1995 from Germany to Hungary. Limnologische Berichte Donau 1, 143-148. KISS, K

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A.C.S. Peacock, Claudia Glatz and T. Emre Şerifoğlu

Open access

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

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

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.

Open access

Jana Medvecká, Jozef Halaška, Klaudia Jomova and Jan Moncol

Structures of copper(II) 2-chlorobenzoate monohydrate and copper(II) 3,5-dichlorobenzoate trihydrate

The crystal structures of the title compounds, [Cu2(μ2-2-Clbz)4(H2O)2] (1) and [Cu(3,5-Cl2bz)2(H2O)3] (2), have been redetermined at 150 K. The compound 1 forms dimeric complex where two Cu2+ cations are bridged through four 2-chlorobenzoate ligands. The Cu2+ ion in 1 is pentacoordinated by four oxygen atoms of bridging 2-chlorobenzoate ligands and one coordinated water molecule. The compound 2 forms mononuclear complex, where the Cu2+ ion is pentacoordinated by two oxygen atoms of monodentate 3,5-dichlorobenzoate ligands and three coordinated water molecule. Both complexes are connected through O—H· · ·O hydrogen bonds into frameworks. The π-π stacking interactions are also observed in crystal structure of 2.

Open access

Lenka Rottmannová, Kraiwan Punyain, Ján Rimarčík, Vladimír Lukeš, Erik Klein and Anne-Marie Kelterer

Theoretical study of 2-phenylpyrrole molecule using various quantum-chemical approaches

A systematic theoretical study of 2-phenylpyrrole (PhPy) is presented for its neutral and monocharged states. The calculations were performed using the semiempirical Austin Model 1 (AM1) method, ab initio Møller-Plesset perturbation theory up to the second-order (MP2), density functional theory (DFT) and its tight-binding approximation (DFTB+). The comparison of the obtained equilibrium geometries showed that the C—C bond lengths in the phenylene ring are practically identical for the neutral state. Electric charging leads to significant changes in the geometry with respect to the neutral state. The C—N bonds in PhPy are elongated and the negative charging produces the out-of-plane distortion of N—H bond from the aromatic ring plane. The anionic state of the investigated molecule is connected with a higher perturbation of bond length alternation in both rings in comparison to the cationic state. The vibrationaly broadened absorption spectra, based on the on-the-fly molecular dynamics (MD) simulations, are also presented and compared with experimental spectra. Although the DFTB+ method has the tendency to planarize the investigated molecular structure, the agreement of simulated absorption spectra based on the MD DFTB+ geometries with TD-DFT calculations is acceptable.