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(11/10) Ученые из ИФХЭ РАН и МГУ под руководством Ольги Виноградовой поняли, как «полосатая» гидрофобность..
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(11/10) Ученые обнаружили пути проникновения вирусов гриппа и ВИЧ в организм
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(17/04) Курс “Анализ геномных данных”, Москва, 2 – 11 июля 2012
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(12/03) Впервые получено изображение атомов, движущихся в молекуле
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Results 31 - 40 of 134
31.

Technology of Integrated Usage of Fullerene Materials in Sorbent Production

 

M. L. Podvyaznikov, V. V. Samonin, E. A. Spiridonova, and V. Yu. Nikonova

St.-Petersburg State University of Technology, Moskovskii pr. 26, St.-Petersburg, 190013 Russia

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Received June 5, 2008

 

Abstract — Information about the main directions of the developing production technology of adsorbing materials, containing bound fullerenes, is given. The most promising is the usage of fullerene microquantities as a modifier of sorbing materials of diverse nature, which substantially increases their activity.

 

PACS numbers: 68.43.-h

DOI: 10.1134/S2070205109020129
10/04/2009 | 807 Hits | Print

32.

Adsorption of Formaldehyde at Mineral Nanoporous Sorbents Exposed to a Pulse Magnetic Field

L. I. Bel’chinskaya*, N. A. Khodosova*, and L. A. Bityutskaya**

* Voronezh State Forestry Engineering Academy, ul. Timiryazeva 8, Voronezh, Russia

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** Voronezh State University, Universitetskaya pl. 1, Voronezh, Russia

Received June 5, 2008

 

Abstract — The influence of the preexposure of various nanoporous aluminosilicate sorbents to a pulse magnetic field on the adsorption of the formaldehyde vapor was considered. The effect of the pulse magnetic field on the surface morphology of the sorbents and intensifying the sorption activity was estimated. A magnetic field with B = 0.011 T intensified the adsorption by a montmorillonite sample, while an increase in the magnetic induction from 0.011 to 0.12 T enhanced the adsorption by clinoptilolite-containing samples. A combination of the pulse magnetic field (B = 0.011 T) and thermal treatment intensified the adsorption of formaldehyde at all the sorbents studied. The sorbents exposed to the pulse magnetic field were most active 48 h after the exposure. The relaxation time was 72 h for all the systems studied at different B values.

 

PACS numbers: 68.43.-k

DOI: 10.1134/S2070205109020130
10/04/2009 | 768 Hits | Print

33.

Binder Influence on the Structural and Mechanical Properties of Porous Silicate Ceramics

A. I. Rat’ko, A. I. Ivanets, E. A. Stepanova, and S. M. Azarov

 

Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus,
ul. Surganova 9/1, Minsk, 220072 Belarus

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Received June 5, 2008

 

Abstract — The influence of aluminum- and silicon-based binders on the structural and mechanical properties of porous silicate ceramics constructed from powdery structural elements was studied. Data from x-ray powder diffraction analysis, differential thermal analysis, IR spectroscopy, and scanning electron microscopy allowed to propose a structuration mechanism during high-temperature treatment of ceramic samples composed of crystalline silica and an aluminosilicate binder.

 

PACS numbers: 81.05.Je,Mh

DOI: 10.1134/S2070205109020142
10/04/2009 | 823 Hits | Print

34.

Influence of the Carbonization Conditions on the Formation of the Porous Structure of Activated Carbon from Cotton Lignin

M. G. Ismailova

 

Sultanov Research Institute of Pharmaceutical Chemistry, Uzbekistan

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Received June 5, 2008

 

Abstract — Carbonization (thermal pyrolysis) is the determining step in the formation of the porous structures and other physicochemical properties of activated carbons obtained from cotton lignin. Activation of the samples carbonized at 800frame0frame1 produces carbon sorbents with the optimum parameters.

PACS numbers: 68.43.-h

DOI: 10.1134/S2070205109020154
10/04/2009 | 960 Hits | Print

35.

Investigation of Calcareous Deposits Formation on Copper and 316L Stainless Steel under Cathodic Polarization in Artificial Seawater1

 

M. Sarlak, T. Shahrabi, and M. Zamanzade

Department of Materials Science and Engineering, Faculty of Engineering, Tarbiat Modares University,
Nasr bridge, Tehran, Iran

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Received July 17, 2007

 

Abstract — The formation and growth of calcareous deposits on 316L stainless steel and copper under cathodic polarization in artificial seawater were investigated by electrochemical tests and analytical techniques such as SEM, EDX and XRD. The deposits mineral compositions were related to the types of metallic materials and were different on each substrate. On 316L stainless steel at potentials less negative than the water reduction potential (–1100 mV/SCE), the deposits were composed of aragonite with low amounts of brucite; at the potentials more negative than the water reduction potentials, only of brucite. Around the water reduction potentials, the deposits were composed of both aragonite and brucite together. However the formation of brucite was noted before activating the water reduction processes. The results were moderately similar to that on mild steel and the type of deposited phases depended on potentials, at which the cathodic protection was carried out. The deposits formed on copper differed from those on 316L stainless steel and the types of deposited phases were independent from water reduction potential on copper (–1150 mV/SCE). Hence, the deposits were composed only of aragonite at all potential ranges. Due to the low current densities observed in chronoamperometric curves during cathodic polarization and in sufficient alkalinity, it seemed that the brucite could not deposit on this metallic substrate.

 

PACS numbers: 31.65.Kn

DOI: 10.1134/S2070205109020166
10/04/2009 | 1050 Hits | Print

36.

Constant Magnetic Field Refinement of Chromium-free Conversion Coatings on AZ31 Magnesium Alloy

 

G. Bikulcius, A. Rucinskiene, E, Sudavicius, and A. Selskis

Institute of Chemistry, ul. Goshtauto 9, Vilnius, 01018 Lithuania

Received October 02, 2007

 

Abstract—By the electrochemical protective efficiency of conversion coatings on an AZ31 alloy, it is shown that the corrosion stability of AZ31 alloy depends on the activating solution treated with magnetic field. Scanning electron microscopic studies demonstrate that the surface morphology of conversion coatings is identical irrespective of the magnetic field treatment. The cross-section composition of conversion coatings is deter-mined by x-ray photoelectron spectroscopy (XPS). XPS data demonstrate that a conversion coating treated with magnetic field is thicker than coatings nonsubjected to this treatment. It is also shown that a conversion coating of AZ31 alloy mainly consists of oxides and hydroxides, namely, MgO, Mg(OH)2, MgF2 and Al2O3, MgAl2O4. However, when magnetic field is applied, the aluminum concentration increases from 0.73 to 6.65 at. %, and the fluorine concentration decreases from 12.06 to 8.11 at. %.

 

PACS numbers: 81.65.Kn

DOI: 10.1134/S2070205109020178
10/04/2009 | 911 Hits | Print

37.

Peculiarities of Long-Term Effect of Hydrosulfide-Enriched  Seawater on a Copper Alloy

I. E. Zanin, V. Yu. Kondrashin, V. N. Latartsev, and V. V. Chernyshev

 

Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russia

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Received May 26, 2007

 

Abstract — Copper specimens (coins) found at the bottom of Taman bay, which lied in water for about 1600years, manifested a very high corrosion resistance. The uniqueness of the phenomenon is attributed to the heightened concentration of hydrogen sulfide caused by the activity of mud volcano in this region. Under the layer of insoluble corrosion products, namely copper sulfides and disulfides, the items preserved the original surface relief.

PACS numbers: 82.45.Bb

 

DOI: 10.1134/S207020510902018X
10/04/2009 | 981 Hits | Print

38.

Electrochemical Behaviour of Zinc in Chloride and Acetate Solutions1

G. Kilinframe0frame1eker and H. Galframe2p

 

a Cukurova University, Department of Chemistry, Adana, Turkey

b Eastern Mediterranean University, Department of Chemistry, G. Magusa, T.R.N.C.

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Received August 14, 2007

 

Abstract — The corrosion behaviour of zinc in chloride medium was investigated in the absence as well as the presence, of acetate ions. The temperature effect was also investigated by varying the temperature in a range of 298 to 328 K, while the pH was kept constant at 8.5. Polarization resistance (Rp) and activation energy (Ea) values were determined, by means of potentiodynamic and EIS measurements. Thermodynamic properties were evaluated with the current-potential measurements. The temperature, ionic species and the parts of oxide film on anodic and cathodic processes are discussed. It was shown that zinc acetate [Zn(CH3COO)2] formation could provide important protection with other zinc corrosion products, against the attack of corrosive environment.

 

PACS numbers: 82.45.Hk

DOI: 10.1134/S2070205109020191
10/04/2009 | 987 Hits | Print

39.

Recent Trends in Experimental and Theoretical Investigations of Chemisorption on Metal-Electrolyte Interface. II. Contact Electric Resistance Method1,2

V. A. Marichev

 

Department of Chemistry, University of Western Ontario, London, Ontario, Canada

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Abstract — New trends in experimental and theoretical investigations of chemisorption on electrodes are considered on examples of in situ spectroscopic studies and the density functional theory calculations. The partial charge transfer during ionic and molecular adsorption from aqueous solutions on coinage and platinum metals and the thermodynamic uncertainty regarding the direction of the charge transfer are discussed. The contact electric resistance technique (CER) was shown to offer a new approach to considering these problems. This technique provides information on the coefficient and direction of the charge transfer, the kinetics of the transformation of the electrode surface during the conversion of adsorbed ions to adatoms, and the role of competitive adsorption of water. It was examined how the charge transfer is related to the electrosorption valence of anions and what the role plays the tunneling of electrons in the generation of the CER signal. The CER was demonstrated to be dependent on the potential E, the coverage, and the residence charge of the adsorbate. For the adsorption of halide ions from aqueous solutions on 1B metals, the bell shaped CER vs. E dependences were obtained. The maxima in these dependences correspond to the onset of substantial charge transfer, their position and amplitudes being determined by the nature of the metal and anion and the concentration of the latter. At E< Emax, halide ions are adsorbed without appreciable charge transfer; within the range Emax (Emax 0.1 V), the charge transfer for silver and gold approaches 1, being far less for copper. For a given metal, Emax increases in the series frame0 < frame1 frame2 frame3 while for a given anion, Emax increases in the series Au < Ag frame4 Cu. Based on the measured CER-E dependences, a quantitative criterion of the substantial charge transfer during ionic and molecular adsorption was proposed. This criterion was demonstrated to be consistent with the published data on charge transfer in various adsorbate-adsorbent systems. In particular, it shows that the hydrophilicity and electronic properties of 1B metals differently influence charge transfer during ionic and molecular adsorption. New electrosorption equations have been proposed describing the partial charge transfer and screening of the adsorbate charge due to partial ionization of the surface atoms. An experimental approach to solve the “anion problem” in the density functional theory has been developed basing on the CER-measured values of Emax in corresponding electrochemical systems.


PACS numbers: 68.43.–h, 78.30.–j

 

DOI: 10.1134/S2070205109030010
22/06/2009 | 932 Hits | Print

40.

Kinetics of Phase Transformations in a Binary Alloy Surface Layer at the Selective Dissolution. II. Agframe0Au|Ag+* System

O. A. Kozaderov, A. V. Vvedenskii, and O. V. Koroleva

 

Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russia

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Received April 12, 2008

 

Abstract — Based on the theoretical investigation [1], the conditions of phase transformation of gold on Ag–Au alloy surfaces, which are selectively dissolved in a nitrate environment at the overcritical anodic polarization, are experimentally found. Kinetic regularities of the formation of Au° individual gold phase on the alloy surface depending on the alloy composition and overpotential, as well as on the presence of surface active organic substances in the solutions and the passivating alloying additives in the alloy are determined.

PACS numbers: 82.45.Qr

 

DOI: 10.1134/S2070205109030022
22/06/2009 | 936 Hits | Print

  

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