In English. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.



Volume 50 No. 1 March 2001


Editorial; 3–4

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Comparison of advanced oxidation processes for the destruction of 2,4-dinitrophenol; 5–17

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Anna GOI and Marina TRAPIDO

Abstract. Several advanced oxidation processes such as hydrogen peroxide photolysis, the Fenton treatment, photo-Fenton treatment, and ozonation combined with hydrogen peroxide and UV-radiation for the destruction of 2,4-dinitrophenol were studied. Advanced oxidation processes, especially the Fenton treatment, were found to be effective for the degradation of 2,4-dinitrophenol and removal of toxicity. According to the Daphnia magna acute toxicity test, advanced oxidation led to complete detoxification of 2,4-dinitrophenol. Also a high degree of nitrogen mineralization during advanced oxidation was achieved.

Key words: advanced oxidation processes, 2,4-dinitrophenol, destruction, toxicity, biodegradability, nitrogen mineralization.

Mass transfer in a liquid–liquid ozonation process; 18–27

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Abstract. A liquid–liquid phase ozonation process for the removal of phenolic compounds from an aqueous solution using fluorinated organic solvents as the ozone carrier was studied. The experimental results showed that the oxidation of phenolic compounds by ozone is a mass transfer process accompanied by a surface reaction in the boundary layer of both the aqueous and the organic phase, whose role depends on the distribution coefficients and concentrations of reactants. The interfacial mass transfer is enhanced by the chemical reaction. Mass transfer coefficients, enhancement factors, and distribution coefficients of phenol, 4-methylphenol, 4-chlorophenol, and ozone were determined.

Key words: ozonation, fluorinated solvent, mass transfer, phenol, 4-methylphenol, 4-chlorophenol.

Modulation of [3H]-8-OH-DPAT binding to rat brain membranes by metal ions; 28–38

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Annemari ARRO, Ain UUSTARE, Jaanus HARRO, and Ago RINKEN

Abstract. The binding of [3H]-8-OH-DPAT to rat hippocampal and cortical membranes was specific and saturable with Kd = 0.87 ± 0.18 nM and Kd = 2.4 ± 0.9 nM, respectively. Guanine nucleotides decreased the [3H]-8-OH-DPAT binding affinity without significant influence on the number of binding sites. The radioligand binding affinity was only slightly affected by the pH in the interval from 6 to 9. The 5-HT1A receptors in cortical membranes were considerably more stable than in hippocampus, indicating that the lipid environment determines the stability of the receptor in these brain regions. All chlorides of monovalent metals studied at concentrations above 30 mM decreased the [3H]-8-OH-DPAT binding. A significant increase in 2 nM [3H]-8-OH-DPAT binding to hippocampal membranes was found in the presence of millimolar concentrations of MgCl2, CaCl2, BaCl2, MnCl2, CoCl2, and NiCl2, while the radioligand binding to cortical membranes was inhibited. It is proposed that different G proteins are coupled to 5-HT1A receptors in rat hippocampus and cerebral cortex.

Key words: 5-HT1A receptors, [3H]-8-OH-DPAT, rat hippocampus, rat cerebral cortex, stability, heavy metals.

Volatile constituents of Matricaria recutita L. from Estonia; 39–45

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Anne ORAV, Tiiu KAILAS, and Kaire IVASK

Abstract. The volatile constituents of Matricaria recutita L. cultivated in Estonia were isolated by SDE and studied by GC/FID and GC/MS. Thirty-seven components were identified. The main components were bisabolol oxide A (20–33%) and B (8–12%), bisabolon oxide A (7–14%), (E)-b-farnesene (4–13%), a-bisabolol (8–14%), chamazulene (5–7%), and en-yn-dicycloether (17–22%). The content of sesquiterpenoid compounds was high, amounting to 70% of the total oil. Variations in the essential oil composition of different chamomile samples and the yields of oil during distillation are also reported.

Key words: Matricaria recutita L. (M. chamomilla L.), Compositae, chamomile, volatile oil SDE extract, GC/FID, GC/MS.

Ion chromatographic determination of major anions and cations in Antarctic ice; 46–51

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Abstract. The ionic content of polar ice sheet is useful in tracing the sources of impurities, which lead to the final composition of the atmosphere. Ion chromatography is a suitable tool for analysing the ionic content of polar ice, provided precautions are taken to avoid ice contamination during sampling and analyses. In the present study a method for handling and analysing ice core samples was developed. The knowledge obtained was then applied for the determination of major ions in Dome B (East Antarctica) ice core to analyse the potential of extracted information for understanding the past atmospheric changes.

Key words: ion chromatography, polar ice.




Estonian Academy of Sciences: Meeting the challenges for 2000–2004. Framework of activities; 52–53

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