Chemical relaxation experiments on mixed conducting oxides with large stoichiometry deviations

2015 ◽  
Vol 280 ◽  
pp. 66-73 ◽  
Author(s):  
Andreas Falkenstein ◽  
David N. Mueller ◽  
Roger A. De Souza ◽  
Manfred Martin
Keyword(s):  
Conducting Oxides ◽  
Chemical Relaxation ◽  
Relaxation Experiments

Transient Formation of a Complex Between α-Chymotrypsin, Proflavin, and Tosylarginine Methyl Ester (TAME)

1972 ◽  
Vol 50 (3) ◽  
pp. 257-260 ◽  
Author(s):  
George H. Czerlinski ◽  
Catherine Odell
Keyword(s):  
Methyl Ester ◽  
Ternary Complex ◽  
Competitive Inhibitor ◽  
Relaxation Processes ◽  
Relaxation Time Constant ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
Fast Relaxation ◽  
Chemical Relaxation ◽  
Relaxation Experiments

Chemical relaxation experiments were conducted on the reaction of α-chymotrypsin, with the competitive inhibitor proflavin and the substrate analogue TAME (tosylarginine methyl ester) in phosphate buffer, pH 6.7, observing transmission changes at 465 mμ. Two chemical relaxation processes were observed with the slow one attributed to a monomolecular interconversion of the enzyme–substrate complex. The concentration dependence of the reciprocal fast relaxation time constant only agrees with the equations derived for the involvement of a labile ternary complex between enzyme, substrate, and inhibitor (as simplest model).

Measuring oxygen surface exchange kinetics on mixed-conducting composites by electrical conductivity relaxation

2015 ◽  
Vol 3 (19) ◽  
pp. 10296-10302 ◽  
Author(s):  
Bobing Hu ◽  
Yunlong Wang ◽  
Zhuoying Zhu ◽  
Changrong Xia ◽  
Henny J. M. Bouwmeester
Keyword(s):  
Dual Phase ◽  
Conductivity Relaxation ◽  
Surface Exchange ◽  
Electrical Conductivity Relaxation ◽  
Chemical Relaxation ◽  
Relaxation Experiments ◽  
Exchange Kinetics ◽  
Heterogeneous Phase ◽  
Oxygen Surface Exchange ◽  
Oxygen Surface

Chemical relaxation experiments in reducing atmospheres show little to no contribution of heterogeneous phase-boundaries to oxygen surface exchange kinetics on Sr2Fe1.5Mo0.5O6−δ–Sm0.2Ce0.8O2−δ dual-phase composites.

Interaction of H2O, O2 and H2 with Proton Conducting Oxides Based on Lanthanum Scandates

2019 ◽  
pp. 88-100
Author(s):  
A. S. Farlenkov ◽  
N. A. Zhuravlev ◽  
Т. A. Denisova ◽  
М. V. Ananyev
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Gas Phase ◽  
Molecular Hydrogen ◽  
Proton Magnetic Resonance ◽  
Partial Pressure Of Oxygen ◽  
Proton Conducting ◽  
Conducting Oxides ◽  
Temperature Range ◽  
Apparent Level

The research uses the method of high-temperature thermogravimetric analysis to study the processes of interaction of the gas phase in the temperature range 300–950 °C in the partial pressure ranges of oxygen 8.1–50.7 kPa, water 6.1–24.3 kPa and hydrogen 4.1 kPa with La1–xSrxScO3–α oxides (x = 0; 0.04; 0.09). In the case of an increase in the partial pressure of water vapor at a constant partial pressure of oxygen (or hydrogen) in the gas phase, the apparent level of saturation of protons is shown to increase. An increase in the apparent level of saturation of protons of the sample also occurs with an increase in the partial pressure of oxygen at a constant partial pressure of water vapor in the gas phase. The paper discusses the causes of the observed processes. The research uses the hydrogen isotope exchange method with the equilibration of the isotope composition of the gas phase to study the incorporation of hydrogen into the structure of proton-conducting oxides based on strontium-doped lanthanum scandates. The concentrations of protons and deuterons were determined in the temperature range of 300–800 °C and a hydrogen pressure of 0.2 kPa for La0.91Sr0.09ScO3–α oxide. The paper discusses the role of oxygen vacancies in the process of incorporation of protons and deuterons from the atmosphere of molecular hydrogen into the structure of the proton conducting oxides La1–xSrxScO3–α (x = 0; 0.04; 0.09). The proton magnetic resonance method was used to study the local structure in the temperature range 23–110 °C at a rotation speed of 10 kHz (MAS) for La0.96Sr0.04ScO3–α oxide after thermogravimetric measurements in an atmosphere containing water vapor, and after exposures in molecular hydrogen atmosphere. The existence of proton defects incorporated into the volume of the investigated proton oxide from both the atmosphere containing water and the atmosphere containing molecular hydrogen is unambiguously shown. The paper considers the effect of the contributions of the volume and surface of La0.96Sr0.04ScO3–α oxide on the shape of the proton magnetic resonance spectra.

Correlation between electrical and rheological measurements on sewage sludge

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
E. Dieudé-Fauvel ◽  
J.-C. Baudez ◽  
P. Coussot ◽  
H. Van Damme
Keyword(s):  
Sewage Sludge ◽  
Rheological Parameters ◽  
Clear Correlation ◽  
Electrical Measurements ◽  
Rheological Measurements ◽  
Sludge Characterization ◽  
Relaxation Experiments ◽  
Rheological Experiments ◽  
The One ◽  
Microstructure Of The Material

In order to improve sewage sludge characterization for both dewatering and agricultural spreading, we have studied their electrical and rheological properties. On the one hand, electrical measurements give a picture of the microstructure of the material (charges, particles mobility), whereas on the other hand, rheological experiments describe its macrostructure (consistency). The interactions of the matter are the link between them. Our results showed that sludge becomes more conductive when its dry content (for a defined composition) or the temperature increases, and also during aging. In parallel its apparent viscosity increases with the dry content but decreases with the temperature or during aging. In each case a clear correlation was found between electrical and rheological parameters. This relationship clearly depends on sludge composition, and also on parameters such as the temperature, the observation frequency, the velocity range in the case of relaxation experiments. Finally, those types of experiments can be correlated to improve the comprehension of sludge structure and consistency characterization.

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