Fractional composition of nitrogen compounds in forest-steppe Chernozems.

The N-containing component of humic acids regularly and significantly changes downward in the profile of forest-steppe Chernozems, affecting the total nitrogen content, its fractional composition, and the amino acid composition. -from Journal summar

Study of the nitrogen-containing component of humic acids in forest-steppe Chernozems.

Regular changes are shown to occur in the nitrogeneous component of humic acids with increasing depth in the profile of Chernozems. -from Journal summar

Humus Content and Composition in the Water-Stable Aggregates of Dark Gray Forest Soils

Humus distribution and composition in different fractions of water-stable soil aggregates isolated from the samples of the humus horizon of dark gray forest soil were studied by the Han method. Total humus content and the content of its most hydrophobic and low-molecular fractions in the water-stable aggregates tend to decrease with a decrease in aggregate size. This regularity is less manifested in the lower layers of the humus horizon in comparison with its upper layers

On the chemical structure of humic substances in soils

Humic substances are present in real soils as a nonvalently and valently bound ensemble that belongs to a group of spatially structured systems, in which the heterogeneity of adsorption surfaces of secondary minerals is associated, in a complicated manner, with the heterogeneity of organic macromolecules and intra- and intermolecular links. An indefinite multitude of possible macromolecular conformations of humic substances can correspond to the minimum of free energy in the whole structured system

The structure of chromatophores from purple photosynthetic bacteria fused with lipid-impregnated collodion films determined by near-field scanning optical microscopy

AbstractLipid-impregnated collodion (nitrocellulose) films have been frequently used as a fusion substrate in the measurement and analysis of electrogenic activity in biological membranes and proteoliposomes. While the method of fusion of biological membranes or proteoliposomes with such films has found a wide application, little is known about the structures formed after the fusion. Yet, knowledge of this structure is important for the interpretation of the measured electric potential. To characterize structures formed after fusion of membrane vesicles (chromatophores) from the purple bacterium Rhodobacter sphaeroides with lipid-impregnated collodion films, we used near-field scanning optical microscopy. It is shown here that structures formed from chromatophores on the collodion film can be distinguished from the lipid-impregnated background by measuring the fluorescence originating either from endogenous fluorophores of the chromatophores or from fluorescent dyes trapped inside the chromatophores. The structures formed after fusion of chromatophores to the collodion film look like isolated (or sometimes aggregated, depending on the conditions) blisters, with diameters ranging from 0.3 to 10 μm (average ≈1 μm) and heights from 0.01 to 1 μm (average ≈0.03 μm). These large sizes indicate that the blisters are formed by the fusion of many chromatophores. Results with dyes trapped inside chromatophores reveal that chromatophores fused with lipid-impregnated films retain a distinct internal water phase

Theory and practice of unit creation for technogenic material compacting

No Abstrac

Application of Membrane Filtration to Prevent Microbial Contamination of Lysimeter Water

Ultrafiltration is suggested for the elimination of artifacts evolved from the biochemical transformation of water-soluble organic substances in lysimeter collectors. A membrane filter installed between the vessel of the lysimeter and its collector provides the separation of microbial cells from water-soluble organic substances immediately at the infiltrate accumulation

Separation of the Groups of Humic Substances upon Recurrent Treatment with Solvents

The recurrent (up to 20 times) reprecipitation of an alkaline extract from the Al horizon of dark gray forest soil by acids at pH 1.5 does not provide a complete separation of the acid-soluble fraction from the acid-insoluble residue of humic substances. A satisfactory separation of the residue into hymatomelanic and humic acids can be achieved by several treatments with dioxane, provided that the residue is subjected to reprecipitation before every extraction procedure

Kinetics of the process of ion exchange and specific adsorption in water-stable aggregates

The results of investigation of the kinetics of processes of potassium ion exchange and copper adsorption by water-stable aggregates of dark-gray forest soil are considered. It is supposed that the specific adsorption of Cu(II) is limited by internal diffusion. Copyright © 1996 by MAHK Hayka/Interperiodica Publishing