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The formation of bimetallic composites by the electrochemical codeposition of Fe(III)Cl-5,10,15,20-tetrakis(4-aminophenyl)porphyrin and Mn(III)Cl-5,10,15,20-tetrakis(4-aminophenyl)porphyrin was studied. The composites were obtained by the superoxide-assisted electrochemical deposition from mixed solutions of DMSO with equal concentrations of porphyrins. The spectral analysis of the composites showed that they were enriched in the Mn complexes of porphyrin. A comparative analysis of the morphology, electroactive surface area, and specific features of oxygen electroreduction on the films of individual porphyrins and the composites was carried out. It was shown that the catalytic activity of bimetallic composite was higher than that of the materials based on the individual metal complexes. [ABSTRACT FROM AUTHOR]

This work confirms formation of surface films of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (H2T(4-NH2Ph)P) in dimethylsulfoxide in the potential range of oxygen electroreduction. Kinetics of variation of faradaic currents and of the interface characteristics are studied at the working electrode potentials of +0.5 V (porphyrin electrooxidation), –0.9 V (oxygen electroreduction), and –1.25 V (coreduction of porphyrin and oxygen). It is shown that the working electrode surface is passivated at the potential of +0.5 V and faradaic currents decrease fast. At the potentials of –0.9 and –1.25 V, the working electrode surface passivation is less pronounced. As shown by analysis of electrode impedance spectra, a film is formed on the electrode surface under electroreduction conditions (–0.9 and –1.25 V), as opposed to electrooxidation conditions (+0.5 V). Charge transport through this film can be characterized by modeling the interface impedance. The kinetics of variation of the interface parameters allow estimating the stage mechanism of film formation and restructuring of the formed layer. [ABSTRACT FROM AUTHOR]

The system Cu/HO-CHOH-CuSO was studied in a wide range of organic component concentrations by the impedance spectroscopy method. In the studied range of ethanol concentrations the diffusion of ions to an electrode is the limiting stage of the electrode process. An increase in the ethanol concentration results in a decrease in the double electrical layer capacity, which is caused by a change in the double electrical layer structure at the electrode-solution boundary. [ABSTRACT FROM AUTHOR]

By the method of impedance spectroscopy the properties of the phase boundary of Cu|H2O + i-C3H7OH + CuSO4 system were investigated. The impedance hodographs were obtained, in the form of circles with displaced centers. The capacity values of electrical double layer, exchange currents, and resistance of the electrolyte solution depending on the mole fraction of 2-propanol were determined. The role of organic component in the formation of the electrical double layer in the studied system is elucidated. [ABSTRACT FROM AUTHOR]

The magnetic susceptibility χ, thermopower α, and resistivity ρ of single crystals of the manganate La0.825Sr0.175MnO3 are investigated in the temperature interval 77–300 K and at pressures to 14 kbar. All of these measurements reveal the presence of a transition to a ferromagnetic metallic state at TC≈280 K and a structural transition at Tstr≈200 K. The pressure coefficients of these transition temperatures are found to be ∂TC/∂P=+1.3 K/kbar and ∂Tstr/∂P=-6.3 K/kbar. The thermopower α(T) is everywhere positive, has a domelike shape, and decreases with increasing pressure. On the χ(T) curve at T≈100 K there is a feature that is shifted to lower temperatures under pressure (∂TM/∂P=-5.8 K/kbar). The physical cause of this feature is discussed. [ABSTRACT FROM AUTHOR]

The pulse incorporation of radiolabelled mannitol, glycerol, thymidine, uridine and protein hydrolysate has been studied during the Escherichia coli growth. The incorporation of carbohydrates and predecessors is sharply changed before and after lag-phase, that is due evidently to the partial synchronization of cell population. Three cell divisions have been found: before lag-phase (determined by the curve of optical density), at the end of it and after it termination. Cell division is accompanied by removal of catabolic repression from glycerol utilization, by increase of protein, RNA and DNA synthesis rates. The rates of biopolymer synthesis decrease sharply at the beginning of lag-phase, but DNA synthesis is going on at a rather high level.

The dynamics of RNA and protein metabolism (as indicated by the incorporation of labeled precursors) during electrophysiological 'learning" and electrical stimulation of isolated ganglia of the snails Tritonia diomedia and Helix pomatia has been investigated. 'Learning" phenomenon manifested itself in the maintenance of synchronous discharges in the electrical activity of the neurons after cessation of the stimulus. At all the electrical stimulations, fast periodic processes of accumulation-degradation of RNA and protein were observed. Radioautographic studies indicate that these processes begin at first in the glia and then in the neurons. The pattern of incorporation of the precursor into the protein is similar to that into RNA, indicating that short-living RNA is involved into the synthesis of short-living proteins. Aurantin (a mixture of actinomycines) inhibits glial synthesis of RNA to a greater extent than neuronal one,-both at rest and electrical stimulation. On the other side, aurantin hinders or even completely blocks "learning" phenomenon. It is suggested that normal RNA metabolism is necessary for the formation of trace phenomena. No essential differences in the metabolism of RNA, protein and nucleotides were found during "learning" and stimulation.

During the cell growth with mixture of three sources of carbon (mannit-arabinose-glycerol, glucose-sorbite-glycerol, glucose-sorbite-galactose) the components of the mixture have been found to be utilized in series. After using up the first, the repression is eliminated unselectively in utilization both the second and the third. Then after the lag-period the utilization repression of the third carbon source by the second one occurs. The phenomenon of "remaining repression" consisting in that at the cell growth with mixture of mannite and sorbite after using up the first carbohydrate the cells cannot start utilizing the second has been described.