Kinetic growth models at different biological development levels

The quasi-chemical biological growth model suggested earlier was used to derive kinetic equations for population growth of various biological species. A cycle of sequential stages of population development can be represented in the form of quasi-chemical equations; the kinetic equations describing the development cycle allow the population size changes to be predicted quantitatively depending on the conditions. As distinct from the extrapolation-simulation model, the kinetic parameters in kinetic biological growth models are the experimental population growth characteristics. The models developed were verified and parametrically identified on the basis of the experimental data to show that they were in agreement with experiment to within measurement errors.     

A sorbent based on phosphorylated lignin

A procedure was developed for preparing an effective sorbent based on lignin phosphorylated in the presence of urea. The phosphorus content was 16.6 wt %. The total exchange capacity was 0.86 mmol g⁻¹ for Cu²⁺ ions and 0.23 mmol g⁻¹ for UO₂²⁺ ions. The effect of urea on the lignin phosphorylation was examined by IR spectroscopy.     

Structure of aldose condensation products with 2-hydroxyand 2-sulfanylbenzohydrazides

The structure of the condensation products of 2-hydroxy- and 2-sulfanylbenzohydrazides with a series of aldoses (L-arabinose, D-ribose, L-ramnose, D-galactose, D-glucose, D-mannose) was studied by ¹H and ¹³C NMR spectroscopy. The condensation products of monosaccharides with 2-hydroxybenzohydrazide in DMSO-d ₆ solution exist as equilibrium mixtures of linear hydrazone and cyclic pyranose and furanose forms, the cyclic tautomers being represented by two stereoisomers (α- and β-anomers). The aldose condensation products with 2-sulfanylbenzohydrazide in the crystalline state have cyclic 1,3,4-benzothiadiazepine structure, while in DMSO-d ₆ solution they undergo complete or partial isomerization into cyclic pyranose tautomer.     

Optical method for detecting variations of the magnetic field strength

A method of detecting the magnetic field variation is proposed and implemented experimentally. The method employs the rotation of the speckle pattern of light transmitted through an optical fiber that is placed into a longitudinal magnetic field and the recording of a holographic grating in a photorefractive crystal using the speckle field. The possibility of detecting the shape of a 0.15-s magnetic field pulse is demonstrated experimentally.     

Mechanism of the protonation of azulenes in aqueous solutions of acids

In aqueous solutions of strong acids (H₂SO₄, H₃PO₄, and HCl) containing azulene, the fast reversible protonation of azulene is accompanied by the slow formation of a disperse dark violet dye insoluble in acids, alcohol, and heptane. On the basis of the kinetic specifics of this reaction and the nonlinear (nearly reciprocal quadratic) dependence of the concentrations ratio of their cationic and neutral forms on the Hammett acidity function known for azulene and 14 of its derivatives, azulene is shown not to be a Hammett base. A mechanism for the reversible reactions of the azulenium cation is proposed that considers supramolecular dimers to be the basic state of azulene and its derivatives. The scheme includes reactions of the unstable intermediate π complexes formed from the dimers and hydrated hydrogen cations; the complexes quickly dissociate in the opposite direction and react with the hydrated protons to yield azulenium cations and unstable molecules that induce polymerization of the dimers.     

A New Branch of the Diversity-Oriented Synthesis Based on 4-Oxoalkane-1,1,2,2-tetracarbonitriles: Synthesis of Cyano-Substituted Iminofuran Derivatives

4-Oxo-3,4-diphenylbutane-1,1,2,2-tetracarbonitrile reacted with aliphatic, aromatic, and heterocyclic aldehydes in the presence of ammonium acetate to afford previously unknown iminofuran derivatives, 5-imino-4-(2-oxo-1,2-diphenylethyl)tetrahydrofuran-3,3,4-tricarbonitriles.     

Effect of the conditions of synthesis and the pH of the medium on the dimensional characteristics of nanocomplexes of selenium with chymotrypsin

The possibility of controlling the dimensions of nanocomplexes of chymotrypsin with selenium nanoparticles by varying the amount of the reducing agent during synthesis, the ratio of the reacting substances’ concentrations, and the pH of the medium is shown by means of static and dynamic light scattering.     

Reactivity with Respect to Bases of 5-Hydroxy-7-oxo-6-azabicyclo[3.2.1]octane-1,2,2-tricarbonitriles

Russian Journal of Organic Chemistry -