Conditions for improving the extraction of substances with antioxidant properties from bearberry (Arctostaphylos Adams) leaves have been studied. It is established that the natural antioxidants are most completely extracted by maceration in a constant electric field (U = 35 V, I = 250 mA) for 2 h at 303 K with stirring. The optimum extractant is 1% aqueous acetic acid with added surfactant (Tween-80, 8.8 × 10− 4 M). This extract increases the stability (storage time) of sunflower oil more than four times. The proposed method of electroextraction increases the yield of extracted substances with antioxidant properties and decreases the yield of ballast substances without complicating the procedure and increasing the consumption of materials.

Conditions of intensification of the extraction of substances with antioxidant properties from the leaves of bearberry (Arctostaphylos Adans) have been studied. It is established that the nature antioxidants are most completely extracted by maceration in a constant electric field (U = 35 V,I = 250 mA) for 2 h at 303 K with stirring. The optimum extractant is 1% aqueous solution of acetic acid with additives of surfactant (Twin-80, 8.8 × 10-4 M). This extract increases the stability (storage time) of sunflower oil more then four times. The proposed method of electroextraction increases the yield of extracted substances with antioxidant properties at a reduced yield of ballast substances without complicating the procedure and increasing the consumption of materials.

The nature of magnetism in all-carbon crystals composed of polymeric layers of covalently bound fullerene (C-60) molecules is considered. The results of quantum-chemical calculations performed using the unrestricted Hartree-Fock approximation and the semiempirical AM1 method are presented. It is shown that the exchange integrals J of both a free C-60 molecule and a monomer unit of the polymer are too large ensure the required magnetic susceptibility of the fullerene crystal. However, the J value exhibits an approximately n-fold decrease for an oligomer molecule consisting of n C-60 units. Therefore, in the case of large n, the exchange integral can be reduced to a low level sufficient to provide for a significant magnetic susceptibility. A nanosize (scaly) model of the observed magnetism is proposed that is consistent with recent experimental data, which are indicative of a nanostructural character of magnetic fullerene samples.

A partly radical character of fullerene molecules is revealed by the presence of effectively unpaired electrons (the same circumstance determines the singlet instability of solutions to the Hartree-Fock RHF and UHF SCF equations). We analyzed the instability of Hartree-Fock solutions, found the stable pure spin singlet state, and determined its energy and the properties of its wave function. Both the energy and wave function of the UHF solution were shown to closely approximate those of the stable solution. We determined the total number of effectively impaired electrons (N-D) and the partial contributions to this number of each atom (N-DA) using the UHF solution. The procedure for calculations and reliability of the results obtained are discussed for the example of several diatomic molecules. The ND and NDA values were calculated for the singlet state of the X-60 (X = C, Si) and C-70 molecules. Independent calculations showed that the distributions of the NDA values and free valence over fullerene atoms were closely similar. This allows NDA to be used as an indicator of the chemical activity of the atoms.

In a study of the reactivity of sterically protected phenols in the reaction with ethylbenzene peroxy radicals as a function of their molecular structure and as compared with unprotected phenols, we have established the major characteristic features of the structure–antioxidant activity relation for phenols of different structures.

A study was made of the chemiluminescence in the course of initiated oxidation of sunflower oil with a luminescence activator in the presence of natural phenols. The kinetic parameters \({{k_2 } \mathord{\left/ {\vphantom {{k_2 } {\sqrt {k_1 } }}} \right. \kern-\nulldelimiterspace} {\sqrt {k_1 } }}\) were determined, which take into account the appearance of chemiluminescence and characterize the antioxidative activity of the phenols.

A computational (quantum-chemical) experiment has been performed on constructing a silicon nanofiber by gas-phase deposition. A model of two-step polymerization has been proposed in which a fullerene Si 60 molecule serves as the main structural unit. The formation of oligomers of the molecule containing from three to eight molecular units explains the discrete values of the fiber width observed experimentally. The formation of a “rouleau” of oligomers leads to fiber growth in terms of length. It is shown that both steps are favorable in energy with the decisive superiority of a high-spin state, which poses the question of considering silicon nanofibers to be molecular magnets.

Advantages and disadvantages of two approaches to electronic structure calculations of molecules using the NDDO approximation are revealed.

The SCF MO LCA0 method in the MNDO approximation has been used to consider the electronic structure of the surface compounds ≡SlODlCl3 (El = C, Si, Ge, Sn), modelled by extended clusters. The thermal stabilities of these groups are compared and conclusions ore drawn about the probable mechanism of the interaction of the surface silanol groups of SiO2 with ElCl4 molecules.

The electronic structure of cluster models of fragments of a. silica surface with defect centers [stressed disiloxane bridges, radical (≡Si, ≡SiO) and ionic (≡Si+, ≡SiO−) groups] and impurity centers (boron and aluminum atoms) has been investigated by the MO-LCAO-SCF method in the MNDO approximation. It has been shown on the basis of an analysis of the energetics of the defect structures (with complete optimization of the geometry of the clusters) that the dehydroxylation of silica with the formation of radical and ionic centers is energetically significantly more favorable than is the formation of disiloxane bridges. The influence of impurity boron and aluminum atoms on the properties of the surface fragments of SiO2 has been considered. It has been shown that the migration of impurity boron atoms, which isomorphously replace silicon atoms in the lattice, from the bulk to the surface of silica is energetically unfavorable.

The MO LCAO SCF method has been used in the MNDO approximation to examine the electronic structures and formation energies for adsorption complexes for water on SiO2 stabilized by hydrogen and coordination bonds. Stabilization by several hydrogen bonds cannot explain the high initial heats of adsorption for dehydrated silica. H2O coordination complexes give higher energies, and hydroxylated silicon atoms on SiO2 are considered as primary water-adsorption centers.

Parameter definition is considered for the AM 1 method, which is a new modification of MNDO incorporating better correction for atomic-core repulsion, so the promising approach can be used to calculate energy and structural characteristics for molecules and adducts. Calculations have been performed on heats of formation, ionization potentials, and dipole moments for various compounds, as well as structure parameters (bond lengths and bond and torsion angles), which are close to the standard ones and reproduce experimental values satisfactorily.