Coadsorption of bulky ions by surfactants. Monomolecular layers of tris(2,2'-bipyridyl)ruthenium(II) complex with sodium lauryl sulphate on glassy carbon, platinium, n-SnO2, and n-Si electrodes

1984 ◽  
Vol 49 (10) ◽  
pp. 2187-2196 ◽  
Author(s):  
Jan Lasovský ◽  
František Grambal ◽  
Miroslav Rypka
Keyword(s):  
Glassy Carbon ◽  
Complex Cation ◽  
Radiant Energy ◽  
Electric Energy ◽  
Sodium Lauryl Sulphate ◽  
Surface Films ◽  
Order Of Magnitude ◽  
Monomolecular Layers ◽  
Self Association ◽  
Semiconductor Electrodes

The electrochemical and photochemical behaviour of tris(2,2'-bipyridyl)ruthenium(II) complex (I) on glassy carbon, platinium, n-SnO2, and n-Si electrodes in the presence of sodium lauryl sulphate (II) was investigated. The surfactant in low concentrations induces self-association of the complex cation and its accumulation in the electrode-solution interface. At the optimum concentrations of sodium lauryl sulphate (cII ~0.6 mmol l-1) and of the complex (cI < 0.1 mmol l-1), monomolecular layers composed of I, II counterions are formed on the electrodes. The formation of the surface films does not depend on the kind of the electrode and improves the sensitivity of the voltammetric determination of I by as much as an order of magnitude. For the semiconductor electrodes, the surface films enhance the efficiency of conversion of radiant energy into electric energy. The effect under study may participate in the photosynthesis of green plants.

scholarly journals The effect of ozone on wet atmospheric corrosion of aluminium of high-voltage lines

2019 ◽  
Vol 294 ◽  
pp. 05010
Author(s):  
Galina Tatarchenko ◽  
Nataliia Beloshitskaya ◽  
Viktor Sychenko ◽  
Vitalii Liashuk
Keyword(s):  
Oxide Film ◽  
Traffic Safety ◽  
Electric Energy ◽  
Protective Layer ◽  
Cyclic Polarization ◽  
Humid Atmosphere ◽  
Electrode Layer ◽  
Positive Side ◽  
Order Of Magnitude ◽  
Auger Spectra

One of the factors influencing traffic safety is the uninterrupted power supply of interlocking devices. As a rule transmission of electric energy is carried out using aluminum wires. In order to assess the reliability of power lines in the work, research was carried out on the influence of ozone on corrosion of aluminum in a humid atmosphere and acidic medium. It was found that the presence of oxygen dissolved in acetic acid leads to anode currents increase, while at crossover ozone, cathode currents increase by an order of magnitude and 2-3 times the anode decreases; the corrosion potential of an Ecor shifts to the positive side at 0.15V. The decrease in the density of anode currents in the presence of ozone proceeds due to the growth of the thickness of the aluminum oxide film. According to the Auger-spectra, the film is increased by 3-4 times compared with the nonzonized medium, due to which the corrosion resistance of aluminum Кm increases from 0.066 to 0.025 g/(m2·h). The rate of formation of oxides depends on the concentration of oxidants in the solution, and on their oxidative activity. According to calculations of thermodynamic factors that determine the preferred route of oxidation, the probability of formation of oxides in the presence of ozone is significantly higher. Local destruction of the protective layer occurs mainly in defective places and places of local increase in pH of the electrode layer. Investigation of the cyclic polarization of a sample of aluminum, pre-cathode activated by a current of 1 mA/cm2 density, showed the presence of hysteresis, which decreases in the next 2-3 cycles. In this case, the exterior of the aluminum shifts to (0.10 ÷ 0.15) V is more positive and the corrosion rate is reduced, which indicates the formation of an oxide film in which irreversible changes occur. The change in the inclination of the polarization curves indicates that the cathodic reaction is delayed and is associated with the change in the structure of the surface layer of the electrode and the diffusion restrictions of ozone recovery.

Fluorescence Microscopy Study of Protein Adsorption at Modified Glassy Carbon Surfaces

2005 ◽  
Vol 58 (4) ◽  
pp. 275 ◽  
Author(s):  
Alison J. Downard ◽  
Sandra L. Jackson ◽  
Emelyn S. Q. Tan
Keyword(s):  
Fluorescence Microscopy ◽  
Ethylene Glycol ◽  
Protein Adsorption ◽  
Glassy Carbon ◽  
Direct Method ◽  
Primary Amines ◽  
Tetraethylene Glycol ◽  
Surface Films ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene

Glassy carbon (GC) surfaces were modified with thin films by means of electrochemically assisted reduction of aryl diazonium salts and oxidation of primary amines. GC plates with modified and unmodified areas were exposed to solutions of fluorescently labelled bovine serum albumin (BSA-FITC). Fluorescence microscopy was found to be a simple and direct method for comparing adsorption of BSA-FITC between the different areas. Modification with methylbenzene, hexylbenzene, poly(ethylene glycol) benzene, and tetraethylene glycol diamine groups increases protein adsorption relative to unmodified GC. Hexylamine and the poly(ethylene glycol) diamine ED-2003 reduce protein adsorption. The results give insight into some factors controlling protein adsorption at these surface films.

Wear Reduction and Surface Layer Formation by a ZDDP Additive

1987 ◽  
Vol 109 (4) ◽  
pp. 577-586 ◽  
Author(s):  
Said Jahanmir
Keyword(s):  
Surface Layer ◽  
Surface Analysis ◽  
Iron Sulfide ◽  
Surface Deformation ◽  
Wear Behavior ◽  
Surface Films ◽  
Contact Loads ◽  
Order Of Magnitude ◽  
Sulfide Content ◽  
Wear Reduction

The results of wear tests and surface analyses confirmed that the wear behavior in the presence of ZDDP is controlled by chemically reacted surface films. Surface analysis by Auger microprobe showed that the reacted layer is composed of iron sulfide and zinc phosphate and that it extends to several hundred Å below the contact surface. It was found that the effectiveness of ZDDP in wear reduction was dependent on the test conditions. Under low loads and temperatures, it decreased wear by two orders of magnitude. However, at higher loads and temperatures, wear was increased by one order of magnitude. Scanning electron microscopy confirmed that at low loads, ZDDP changes the wear mechanism from plowing to a mild form of surface deformation, whereas at high loads plowing is changed to delamination of the surface layer. Surface analysis by Auger showed that higher loads and temperatures had resulted in reduction of sulfur content in the surface films. This reduction is attributed to changes in the reaction kinetics at higher contact temperatures caused by high contact loads and elevated oil temperatures. Since sulfides are usually harder than phosphates, the higher wear rate by delamination is explained by the loss of film strength due to reduction of sulfide content.

scholarly journals Electrochemical and microstructural characterization of platinum supported on glassy carbon

2007 ◽  
Vol 61 (3) ◽  
pp. 135-141
Author(s):  
Sanja Terzic ◽  
Vladislava Jovanovic ◽  
Dusan Tripkovic ◽  
Andrzej Kowal ◽  
Jerzy Stoch
Keyword(s):  
Methanol Oxidation ◽  
Glassy Carbon ◽  
Microstructural Characterization ◽  
Electrochemical Treatment ◽  
Organic Residues ◽  
Remarkable Effect ◽  
Platinum Particles ◽  
Order Of Magnitude

The effect of the electrochemical oxidation of glassy carbon on the deposition of platinum particles and the electrocatalytic activity of platinum supported on oxidized glassy carbon were studied for methanol oxidation in H2SO4 solution. Platinum was potentiostatically deposited from H2SO4 + 6mM H2PtCl6 solution. Glassy carbon was anodically polarized in 1 M NaOH at 1.41 V (SCE) for 35 and 95 s and in 0.5 M H2SO4 at 2V (SCE) for 35; 95 s and 2.25 V for 35 and 95 s. Electrochemical treatment of the GC support leads to a better distribution of platinum on the substrate and has remarkable effect on the activity. The activity of the Pt/GCox electrode for methanol oxidation is larger than that of polycrystalline Pt and by more than one order of magnitude larger than that of a Pt/GC electrode. This increase in activity indicates the pronounced role of the organic residues of the GC support on the properties of Pt particles deposited on glassy carbon.

scholarly journals Effect of glassy carbon properties on the electrochemical deposition of platinum nano-catalyst and its activity for methanol oxidation

2007 ◽  
Vol 72 (2) ◽  
pp. 165-181 ◽  
Author(s):  
Sanja Terzic ◽  
Dusan Tripkovic ◽  
Vladislava Jovanovic ◽  
Amalija Tripkovic ◽  
Andrzej Kowal
Keyword(s):  
Methanol Oxidation ◽  
Glassy Carbon ◽  
Specific Activity ◽  
Carbon Support ◽  
Pt Electrode ◽  
Nano Catalyst ◽  
Platinum Particles ◽  
Different Temperatures ◽  
Order Of Magnitude ◽  
Anodic Polarisation

The effects of the properties of glassy carbon on the deposition of platinum particles and the electrocatalytic activity of platinum supported on glassy carbon (GC/Pt) for methanol oxidation in alkaline and acidic solutions were studied. Platinum was potentiostatically deposited on two glassy carbon samples, thermally treated at different temperatures, which were either polished or anodicaly polarised in acid (GCOX-AC/Pt) and in alkali (GCOX-AL/Pt). Anodic polarisation of glassy carbon, either in alkaline or acidic solution, enhances the activity of both types of GC/Pt electrodes for methanol oxidation. The activity of the catalysts follows the change in the properties of the glassy carbon support upon anodic treatment. The specific activity of the GCOX-AL/Pt electrode for this reaction in alkali is increased only a few times in comparison with the activity of the GC/Pt one. On the other hand, the specific activity of the GCOX-AC/Pt electrode for methanol oxidation in acid is about one order of magnitude higher than that of the GC/Pt electrode. The role of the substrate on the properties of catalyst is discussed in detail. .

Electrochemistry Behavior of Ag/TiO2 Nanobelts and its Potential Applications on Mercapto Proteins Detection

2015 ◽  
Vol 37 ◽  
pp. 85-91
Author(s):  
Yan Min Wang ◽  
Xiu Hong Hao ◽  
Hong Liu
Keyword(s):  
Glassy Carbon ◽  
Phosphate Buffer Solution ◽  
Carbon Electrodes ◽  
Electrochemical Characteristics ◽  
Trace Detection ◽  
Buffer Solution ◽  
Glassy Carbon Electrodes ◽  
Potential Applications ◽  
Order Of Magnitude ◽  
Electrochemistry Behavior

Glassy carbon electrodes (GCEs) were modified by TiO2 and Ag/TiO2 heterostructured nanobelts, respectively. The corresponding electrodes were marked as TiO2/GCE and Ag/TiO2/GCE, respectively. The electrochemical properties of Ag/TiO2/GCE had good and stable electrochemical characteristics in phosphate buffer solution (PBS), and it can be applied to the trace detection of L-cysteine. When the concentration of L-cysteine is in 10-7 order of magnitude, it is more sensitive.

STUDIES ON THE ISOLATION OF SPIRILLUM SPUTIGENUM

1957 ◽  
Vol 3 (5) ◽  
pp. 679-686 ◽  
Author(s):  
J. B. Macdonald ◽  
E. M. Madlener
Keyword(s):  
Surface Layer ◽  
Gold Foil ◽  
Selective Inhibition ◽  
Inhibitory Effect ◽  
Sodium Lauryl Sulphate ◽  
Surface Films ◽  
Oral Flora ◽  
Oxidation Reduction ◽  
Marked Inhibitory Effect ◽  
Reducing Substances

Three approaches were used in attempting to improve the method of isolating Spirillum sputigenum from the human oral cavity:(1) attempts to induce spreading surface growth;(2) selective inhibition of interfering organisms;(3) adjustment of oxidation–reduction potentials.Five of eight strains of Spirillum sputigenum grew as spreading surface films on a blood agar medium in which the base was a veal heart infusion. Increase in the amount of spread could not be induced by varying the agar content of the medium. Sodium lauryl sulphate (0.01%) was found to have a marked inhibitory effect on the human oral flora but did not inhibit Spirillum sputigenum. A method of recording potentials of the surface layer of solidified media using a gold foil electrode is described. Changes in potential of the surface layer of a number of media during reduction in a Brewer jar are recorded. Media in which the potential was rapidly reduced supported growth of Spirillum sputigenum. Of several reducing substances added to media, sheep's serum was the most effective in accelerating a drop in potential. Using a medium compounded of veal heart infusion, sodium lauryl sulphate, and sheep's serum, Spirillum sputigenum was recovered in pure culture from 16 out of 21 samples of gingival scrapings.

Figures-of-merit for the technical development and application of advanced oxidation technologies for both electric- and solar-driven systems (IUPAC Technical Report)

2001 ◽  
Vol 73 (4) ◽  
pp. 627-637 ◽  
Author(s):  
James R. Bolton ◽  
Keith G. Bircher ◽  
William Tumas ◽  
Chadwick A. Tolman
Keyword(s):  
Solar Energy ◽  
Organic Contaminants ◽  
Electric Energy ◽  
Advanced Oxidation ◽  
Polluted Water ◽  
Driven Systems ◽  
Figures Of Merit ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Advanced Oxidation Technologies

Advanced oxidation technologies (AOTs), which involve the in situ generation of highly potent chemical oxidants, such as the hydroxyl radical (áOH), have emerged as an important class of technologies for accelerating the oxidation (and hence removal) of a wide range of organic contaminants in polluted water and air. In this report, standard figures-of-merit are proposed for the comparison and evaluation of these waste treatment technologies. These figures-of-merit are based on electric-energy consumption (for electric-energy-driven systems) or collector area (for solar-energy-driven systems). They fit within two phenomenological kinetic order regimes: 1) for high contaminant concentrations (electric energy per mass, EEM, or collector area per mass, ACM) and 2) for low concentrations (electric energy per order of magnitude, EEO, or collector area per order of magnitude, ACO). Furthermore, a simple understanding of the overall kinetic behavior of organic contaminant removal in a waste stream (i.e., whether zero- or first-order) is shown to be necessary for the description of meaningful electric- or solar-energy efficiencies. These standard figures-of-merit provide a direct link to the electric- or solar-energy efficiency (lower values mean higher efficiency) of an advanced oxidation technology, independent of the nature of the system, and therefore allow for direct comparison of widely disparate AOTs. These figures-of-merit are also shown to be inversely proportional to fundamental efficiency factors, such as the lamp efficiency (for electrical systems), the fraction of the emitted light that is absorbed in the aqueous solution, and the quantum yield of generation of active radicals.

Surface Films on Zircaloy-2 Samples Cracked in Neutral Aqueous NaCl by Stress Corrosion

1973 ◽  
Vol 31 ◽  
pp. 46-47
Author(s):  
R.A. Ploc
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Stress Corrosion ◽  
Zirconium Dioxide ◽  
Surface Film ◽  
Surface Films ◽  
Continuous Layer ◽  
Transmission Electron ◽  
Product Film

Samples of low-nickel Zircaloy-2 (material MLI-788-see(1)), when anodically polarized in neutral 5 wt% NaCl solutions, were found to be susceptible to pitting and stress corrosion cracking. The SEM revealed that pitting of stressed samples was occurring below a 2000Å thick surface film which behaved differently from normal zirconium dioxide in that it did not display interference colours. Since the initial film thickness was approximately 65Å, attempts were made to examine the product film by transmission electron microscopy to deduce composition and how the corrosion environment could penetrate the continuous layer.

A controller for safe, convenient operation of LaB6 emitters on electron-beam instruments

1983 ◽  
Vol 41 ◽  
pp. 408-409
Author(s):  
W. J. Abramson ◽  
H. W. Estry ◽  
L. F. Allard
Keyword(s):  
Electron Beam ◽  
Control System ◽  
Thermal Shock ◽  
Appropriate Care ◽  
Electron Guns ◽  
Tungsten Filaments ◽  
Order Of Magnitude ◽  
Main Components

LaB6 emitters are becoming increasingly popular as direct replacements for tungsten filaments in the electron guns of modern electron-beam instruments. These emitters offer order of magnitude increases in beam brightness, and, with appropriate care in operation, a corresponding increase in source lifetime. They are, however, an order of magnitude more expensive, and may be easily damaged (by improper vacuum conditions and thermal shock) during saturation/desaturation operations. These operations typically require several minutes of an operator's attention, which becomes tedious and subject to error, particularly since the emitter must be cooled during sample exchanges to minimize damage from random vacuum excursions. We have designed a control system for LaBg emitters which relieves the operator of the necessity for manually controlling the emitter power, minimizes the danger of accidental improper operation, and makes the use of these emitters routine on multi-user instruments.Figure 1 is a block schematic of the main components of the control system, and Figure 2 shows the control box.

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