| Autor: |
Danilenko, A., Braudo, E., Pavlovskaya, N., Yushkova, E., Zhuravleva, I. |
| Zdroj: |
Biophysics; Feb2011, Vol. 56 Issue 1, p47-50, 4p |
| Abstrakt: |
It has been found by reversed-phase chromatography that humic acids obtained from vermicomposts of different duration of vermicomposting consist of a hydrophilic and a hydrophobic fractions, the hydrophobic fraction having a substantially lower content of charged, probably carboxylic, groups. A change in the sign of the temperature dependence of the heat capacity of dilute aqueous solutions of humic acids at ∼58°C has been found by differential scanning microcalorimetry, which indicates an increase in the hydration of hydrophobic groups. A jump-wise increase in heat capacity in the temperature range from 86 to 90°C was also found, which is perhaps due to hydration of hydrophobic groups in the interior of 'micelles', because of 'devitrification' of the hydrophobic nucleus of micelle-like structures. It was shown that increasing the duration of vermicomposting leads to an increase in the relative content of the hydrophobic fraction of humic acids and in the cooperativity of the thermodynamic transition, which manifests itself as the jump of heat capacity, which probably results from the increase in the 'micelle' size. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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