Effect of medium composition on the monooxygenase activity of immobilized hemin in aniline oxidation

The effect of the composition of the reaction medium on the rate of aniline oxidation to p-aminophenol by hydrogen peroxide on hemin immobilized on -propylimidazole-modified silica has been studied. Organic solvent additives (alcohols, esters and nitriles) are shown to increase the reaction rate. The observed effect is attributed to the decrease of the medium dielectric constant.

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- , , --. , (, , ) . .

     

Colloid-induced structure in liquid crystal media

The structural perturbations induced by colloidal particles immersed in a model nematic subjected to an external field are calculated employing integral equation methods. Maps of the density-orientational distribution about a colloidal particle are obtained, and these provide a microscopic picture of the colloid's nematic coat. We focus on colloidal particles that favor homeotropic anchoring, but planar anchoring cases are also considered. The range and structure of the nematic coat is shown to be significantly influenced by the nature of the anchoring, the size of the colloidal particle, the range and strength of the colloid-nematogen interaction, and the external field strength. All of these factors are discussed.     

Effect of reductant adsorption on the ESR parameters of O

The change in the ESR parameters of O ₂ ^– ion-radicals under the effect of adsorption of reducing molecules on zinc oxide consists in the increase of the Z-component of the g-tensor. This change is assumed to be due to the transition of O ₂ ^– coordination from -to the -type.

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- O ₂ ^– , Z- g-. , O ₂ ^– - -.

     

Reinforced Concrete Fracture Diagnostics under Conditions of Bending by Parameters of the Electric Response to an Impact Action

Technical Physics - Regularities of changes in the stress-strain state of reinforced concrete in the process of testing for four-point bending have been studied. The change in characteristics of...     

Observation of a narrow feature at 1545 MeV in the system of two K S mesons

Preliminary results of examining the system of two K _S mesons in the region of comparatively high transferred momenta are reported. The events were observed in the π^? p interactions at an energy of 40 GeV on the ITEP 6-m magnetic spectrometer with a neutral trigger. At transferred momenta |t|>0.5 GeV², a maximum with width Γ?10 MeV was observed in the K _S K _S system at a mass of 1545 MeV with statistical significance of no less than 6 standard deviations. This phenomenon can be interpreted as the manifestation of a resonance with the indicated parameters.     

Reaction mechanism and principles of choosing catalysts for selective oxidation at C?H bonds

Reaction mechanism for selective oxidation of organic compounds at C–H bonds is discussed. The criteria of selecting catalysts for these reactions have been formulated; 1) fast heterolytic activation of C–H bonds; 2) relatively slow primary activation of oxygen; 3) fast diffusion of oxygen vacancies; 4) fast electron transfer from the adsorbed substrate to catalyst.

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C–H . : 1) C–H ; 2) ; 3) ; 4) .

     

IR spectra of methane adsorbed on MgO

Methane adsorbed on MgO is activated to form CH₃ fragments stabilized on cations and OH groups.

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, MgO CH₃-, OH-.

     

Mechanism of catalysis and factors responsible for oxide catalyst activity in deep oxidation reactions

A general scheme for the deep oxidation mechanism on oxide catalysts including stepwise and concerted mechanisms as well as their mutual transformations is suggested. The principal factor responsible for the activity in the concerted mechanism region is the rate of oxygen binding. For the stepwise mechanism the main factor is the rate of catalyst interaction with oxidizable reactant.

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