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(11/10) Ученые из ИФХЭ РАН и МГУ под руководством Ольги Виноградовой поняли, как «полосатая» гидрофобность..
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Results 81 - 90 of 118
81.

ESR Spectra Modeling for Ordered and Fractal Aggregates of Metal Nanoparticles

S. V. Dolotov

 

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia

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Received March 6, 2008

 

Abstract — ESR spectra are calculated for aggregates of mono- and polydisperse particles designed by special algorithm and characterized by preset values of fractal dimensionality and prefactor. The dependence of ESR spectrum on the aggregate size, fractal dimensionality, external field (for anisotropic aggregates), and character of large and small particles packing in the aggregate in the case of polydisperse system is demonstrated.

 

PACS numbers: 76.30.-v; 75.75.+a

DOI: 10.1134/S0033173208050202
12/09/2008 | 847 Hits | Print

82.

Scanning Electrochemical Diagnostics of Initial Stages of Anodic Dissolution of Carbon Steel in Chloride Containing Solutions

M. A. Petrunin, L. B. Maksaeva, D. N. Tyurin, and V. A. Kotenev

 

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia

Received June 6, 2007

 

Abstract — An optical PC scanner is used in combination with electrochemical methods of controlling the pitting destruction by an example of the initial states of the anodic dissolution of carbon steel St3 in 0.1 M sodium chloride solution. It is shown that under anodic polarization at the active dissolution conditions, the carbon steel surface exhibits noticeable formation of local defects looking as pits. Under free corrosion conditions in chloride-containing media, this pitting includes at least two stages, namely, the pits initiation and their development, where the first stage is completed in 60 min of tests.

 

PACS numbers: 81.70.Fy

DOI: 10.1134/S0033173208050214
12/09/2008 | 921 Hits | Print

83.

Studying Intermolecular Processes in Thin Surface Layers with Microcantilever Transducers. Formation of Protein Fibrils on a Solid Support

G. A. Kiselev, P. V. Kudrinskii, I. V. Yaminskii, and O. I. Vinogradova

 

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,Leninskii pr. 31, Moscow, 119991 Russiae-mail: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

Received April 23, 2008

 

Abstract — The possibility of studying the processes of intermolecular interaction in thin surface layers by means of microcantilever transducer (MCT) are considered. The use of MCT makes it possible to observe the catalytic growth of amyloid fibrils from chemically immobilized lisozyme molecules on the gold or silicon supports at enhanced acidity (pH 3.0) and room temperature, whereas aggregation in the volume occurs under the same conditions at a higher temperature of 57frame0frame1. Forces that arise in the monolayer protein films during their aggregation are analyzed. A correlation is revealed between the development of lateral strains and the growth rate of protein fibrils in the monolayer. It is shown that for a protein covalently immobilized on the silicon (mica) surface, the aggregation rate is 4.6 (as revealed by the analysis of kinetic data on the caltilever bending) and 5 times (according to estimates of the number of fibrils in an AFM image) slower than on the gold surface. A model for calculating the pair interactions between protein molecules in a monolayer during their aggregation is proposed. Using this model and based on the experimental data, the pair interaction forces of lysozyme molecules on the gold and silicon surfaces are calculated. The calculated forces coincide in the order of magnitude with the data of force spectroscopy on the artificial expansion of an aggregate of lysozyme molecules T4 [23]. It is confirmed experimentally that chemical immobilization of lysozyme on the mica surface leads to deformation (flattening) of protein molecules as compared with their native conformation.

 

PACS numbers: 07.79.Lh, 87.64.Dz

DOI: 10.1134/S0033173208060015
24/11/2008 | 1138 Hits | Print

84.

Transfer and Deposition of Carbon- and Nitrogen-containing Radicals and Ions Produced by Glow Discharge in Hydrogen/Methane/Nitrogen Mixtures

A. E. Gorodetskiia, R. Kh. Zalavutdinova, V. L. Bukhovetsa, A. P. Zakharova, G. T. Razdobarin†,b, E. E. Mukhinb, and V. V. Semenovb

 

a Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia

b Ioffe Physicotechnical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021 Russia

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Received November 11, 2007

 

Abstract — Transfer and deposition of the decomposition products of a dc glow discharge with hollow cathode in a hydrogen/methane flow are discussed. Hydrocarbon (a-C:H) films were deposited at inner surfaces of the hollow cathode and quartz tube bounded the discharge. The carbon deposition rate in the hollow cathode was 3–10 times higher than in the positive column and in afterglow range. Acetylene, ethylene, and ethane prevailed in the plasma-reaction gaseous products. When molecular nitrogen was introduced to the near-cathode plasma at a flow rate equal to or higher than that of methane, the carbon deposition rate at the cathode inner surfaces dropped down by 1.5 to 2 orders of magnitude. The carbon that has been consumed in the a-C:H films formation in the cathode is now transformed mainly to hydrogen cyanide (HCN). The carbon deposition rate in the positive column and in afterglow range (T = 300 K) were comparable with those in the H2/CH4 mixture. In the a-C/N:H deposits, the nitrogen concentration was 15 to 25 at %. The experiments showed that nitrogen can be used as a component of the gas flow specially introduced near the mirror in protecting the optical surfaces in diagnostic channels of the ITER tokamak against a-C:H film deposition.

 

PACS numbers: 52.77.Bn; 52.77.Dq; 81.05.Uw; 81.15.Jj

DOI: 10.1134/S0033173208060027


24/11/2008 | 1197 Hits | Print

85.

The Effect of Atomic Hydrogen on the Anodic Dissolution of Iron in a Sulfate Electrolyte Studied with Impedance Spectroscopy

M. A. Maleeva, A. A. Rybkina, A. I. Marshakov, and V. V. Elkin

 

Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia

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Received May 3, 2008

 

Abstract — Impedance spectra of an iron membrane electrode are recorded in a range of the active metal dissolution potentials in an acidic sulfate solution. The rate constants of the elementary adsorption stages of iron dissolution are found to decrease with an increase in the amount of atomic hydrogen. This results in a decrease in the metal surface coverage with intermediate particles of the anodic process.

 

PACS numbers: 82.45.Qr

DOI: 10.1134/S0033173208060039
24/11/2008 | 1132 Hits | Print

86.

Effect of Anodic Surface Treatment of Cobalt Silicides on the Hydrogen Evolution Reaction

V. S. Povroznik, A. B. Shein, and I. N. Mikova

 

Perm' State University, ul. Bukireva 15, Perm’, 614600 Russia

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Received April 17, 2007

 

Abstract — Effect of the anodic surfaces treatment of cobalt silicides with different content of the metal and silicon components on the mechanism and kinetics of hydrogen evolution in acid solutions is studied.

PACS numbers: 82.45.Qr

DOI: 10.1134/S0033173208060040
24/11/2008 | 1149 Hits | Print

87.

Adsorption Properties of Synthetic Piceatannol

K. E. Polunin, P. N. Kolotilov, D. V. Dzardanov, A. V. Larin, and I. A. Polunina

 

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia

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Received July 2, 2008

 

Abstract — The adsorption isotherms of synthetic piceatannol (trans-3,5,3',4'-tetrahydroxystilbene) from nframe0hexane–ethyl acetate at nanodispersed silicon, titanium, and aluminum oxides were measured under static conditions. The adsorption properties of piceatannol and other hydroxystilbenes were compared with those of polyphenols. It was found that piceatannol adsorbs at titanium oxide better than at alumina and silica and almost as well as phloroglucinol adsorbs at these oxides. The adsorption isotherms can be satisfactorily approximated by the Freundlich equation for the model of localized adsorption at energetically heterogeneous sites. The influence of the nature and concentration of the polar components of a binary organic solvent on the adsorption of piceatannol at silica gel was studied by normal-phase chromatography and UV spectroscopy. The dependences of the retention factors of piceatannol and other hydroxystilbenes on the solvent composition were described by a simple analytical equation. The optimum composition of the mobile phase for separation of piceatannol and other stilbenoids was found.

PACS numbers: 82.45.Qr

DOI: 10.1134/S0033173208060052
24/11/2008 | 1127 Hits | Print

88.

Supramolecular Bisporphyrin Cages: Design and Ways of Self-Assembly of Supramolecular Bisporphyrin Structures for Molecular Nanomotors and Nanosensors

Yu. P. Yashchuk, V. S. Tyurin, and I. P. Beletskaya

 

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia

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Received March 6, 2008

 

Abstract — Self-assembly of supramolecular ensembles of coordination bisporphyrins was studied in reactions of meso-tetrakis(3-hydroxyphenyl)porphyrinatozinc with LaCl3, MnCl2, CrCl3, and SnCl2 and exodentate ligands (1,4-diazabicyclo[2.2.2]octane and 4,4'-bipyridyl). A design and ways of self-assembly of bisporphyrins structures were developed.

PACS numbers: 81.16.Fg

 

DOI: 10.1134/S0033173208060064
24/11/2008 | 1188 Hits | Print

89.

Electrochemical Synthesis and Spectroelectrochemical Properties of Nanostructured Polyaniline Layers in the Presence of Various Polyamidosulfonic Acids

 A. A. Isakova, O. L. Gribkova, A. A. Nekrasov, V. F. Ivanov, V. A. Tverskoi*, and A. V. Vannikov

 

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia

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* Lomonosov State Academy of Fine Chemical Technology, pr. Vernadskogo 86, Moscow, 117571 Russia

Received February 29, 2008

 

Abstract — Electrochemical matrix polymerization of nanostructured polyaniline layers in the presence of polyamidosulfonic acids differing in the rigidity of the polymer framework was studied in a wide concentration range. The spectroscopic, electrochemical, and morphological properties of the resulting layers were examined. It was found that the accelerated electropolymerization is due to (1) preliminary association of aniline with the sulfo groups of the polyacids and (2) a high local concentration of the protons near its macromolecule. The use of a polyacid with a rigid polymer framework afforded an interpolymer complex with polyaniline in side chains. With a semirigid matrix, both a two-strand complex (characteristic of an acid matrix with a flexible chain) and a branched complex were obtained.

 

PACS numbers: 78.67.Bf

DOI: 10.1134/S0033173208060076
24/11/2008 | 1214 Hits | Print

90.

Nanostructure and Energy Properties of the Stainless Steel X18N10T Surface Studied by Scanning Tunneling Microscopy and Scanning Tunneling Spectroscopy. 2. Measurements at Different Potentials in HCl and H2SO4 Solutions.

Yu. M. Stryuchkova and E. V. Kasatkin

 

Karpov Institute of Physical Chemistry, ul. Vorontsovo pole 10, Moscow, 105054 Russia
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Received Fabruary 13 2008

 

Abstract — Stainless steel Kh18N10T is studied by electrochemical scanning tunneling microscopy (ESTM) and electrochemical scanning tunneling spectroscopy (ESTS) at the interface with solutions of 0.01 N HCl and 0.1 N H2SO4 at the controlled sample and tip potentials. The sample potential varied from –0.46 to +1.14 V in 0.01 N HCl and from –0.06 to +0.74 V (NHE) in 0.1 N H2SO4. It is shown that although in the studied acid solutions at the controlled potential the surface is smother than in air, this does not allow one to determine the extremal values of parameters , , and corresponding to individual properties of Fe, Cr, and Ni or their oxides. It is shown that compared to the steel nanorelief, the sample potential has a stronger effect on the electrophysical properties that determine the tunneling transfer of electrons.

 

PACS numbers: 68.37.Ef, 81.07.-b

DOI: 10.1134/S0033173208060088
24/11/2008 | 1165 Hits | Print

  

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