Generalization of the kinetics of chemical dissolution under conditions of gas formation

1986 ◽  
Vol 50 (5) ◽  
pp. 563-565
Author(s):  
G. A. Aksel'rud ◽  
A. I. Dubynin ◽  
B. I. Duda
Keyword(s):  
Chemical Dissolution ◽  
Gas Formation ◽  
Kinetics Of

Mechanisms and Kinetics of Reactions Leading to Natural Gas Formation during Coal Maturation

2000 ◽  
Vol 14 (2) ◽  
pp. 235-259 ◽  
Author(s):  
Steven J. M. Butala ◽  
Juan Carlos Medina ◽  
Terrence Q. Taylor ◽  
Calvin H. Bartholomew ◽  
Milton L. Lee
Keyword(s):  
Natural Gas ◽  
Gas Formation ◽  
Kinetics Of

scholarly journals Zero Stress Aging of Glass and Carbon Fibers in Water and Oil—Strength Reduction Explained by Dissolution Kinetics

Fibers ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 107 ◽  
Author(s):  
Andreas T. Echtermeyer ◽  
Andrey E. Krauklis ◽  
Abedin I. Gagani ◽  
Erik Sæter
Keyword(s):  
Carbon Fibers ◽  
Fiber Strength ◽  
Glass Fibers ◽  
Dissolution Kinetics ◽  
Strength Degradation ◽  
Strength Reduction ◽  
Chemical Dissolution ◽  
Structural Applications ◽  
Kinetics Of ◽  
Over Time

Understanding the strength degradation of glass and carbon fibers due to exposure to liquids over time is important for structural applications. A model has been developed for glass fibers that links the strength reduction in water to the increase of the Griffith flaw size of the fibers. The speed of the increase is determined by regular chemical dissolution kinetics of glass in water. Crack growth and strength reduction can be predicted for several water temperatures and pH, based on the corresponding dissolution constants. Agreement with experimental results for the case of water at 60 °C with a pH of 5.8 is reasonably good. Carbon fibers in water and toluene and glass fibers in toluene do not chemically react with the liquid. Subsequently no strength degradation is expected and will be confirmed experimentally. All fiber strength measurements are carried out on bundles. The glass fibers are R-glass.

The expansion kinetics of cellular glass in the thermoplastic state under the hydrated mechanism of gas formation

2017 ◽  
Vol 43 (4) ◽  
pp. 330-334 ◽  
Author(s):  
Ya. I. Vaisman ◽  
A. A. Ketov ◽  
Yu. A. Ketov ◽  
M. Yu. Slesarev
Keyword(s):  
Gas Formation ◽  
Cellular Glass ◽  
Kinetics Of ◽  
Thermoplastic State

scholarly journals Photosynthesis under very high oxygen concentrations in dense microbial mats and biofilms

2018 ◽  
Author(s):  
Dirk de Beer ◽  
Volker Meyer ◽  
Judith Klatt ◽  
Tong Li
Keyword(s):  
Microbial Mats ◽  
Removal Rate ◽  
Bubble Formation ◽  
Water Volume ◽  
Energy Costs ◽  
Light Conditions ◽  
Gas Formation ◽  
High Concentrations ◽  
Kinetics Of ◽  
Very High

AbstractUsing microsensors O2concentrations were measured in photosynthetically active microbial mats of up to 3 mM, corresponding to a partial pressure of 3 bar. This could damage mats by internal gas formation, and be inhibitory by formation of reactive oxygen species (ROS) and reduced effectivity of RuBisCo. The reliability of the electrochemical microsensors was checked by creating elevated O2concentrations in a water volume placed inside a pressure tank. A microsensor mounted with the tip in the gassed water bath showed a response linearly proportional to 5.5 mM corresponding to 4 bar pure O2pressure. After release of the pressure the O2concentration reduced quickly to 2.5 mM, then stabilized and subsequently reduced slowly over 14 hours to approximately 2 mM. We concluded that the very high O2concentrations measured in phototrophic microbial mats are real and O2oversaturation in mats is a stable phenomenon. As consequence of high O2concentrations, net production of H2O2occurred. The accumulation was, however, limited to the respiratory zone under the photosynthetic layer. Despite the high gas pressure inside mats, no disruption of the mat structure was apparent by bubble formation inside the mats,and bubbles were only observed at mat surfaces. Additions of H2O2to high concentrations in the water column were efficiently removed in the photosynthetically active zone. As the removal rate was linearly proportional to the H2O2influx, this removal occurred possibly not enzymatically but by abiotic processes. Phototrophic microorganisms can produce O2at high rates under strongly elevated O2levels, despite the decreased efficiency due to the unfavorable kinetics of RuBisCo and energy costs for protection. Under non-limiting light conditions, this apparent dilemma is, however, not disadvantageous.ImportanceBiofilms are often used in photobioreactors for production of biomass, food or specialty chemistry. Photosynthesis rates can be limited by high O2levels or high O2/CO2ratios which are especially enhanced in biofilms and mats, due to mass transfer limitations. High O2may lead to reactive O2species (ROS) and reduce the efficiency of RuBisCo. Moreover, gas formation may destabilize their structure. Here we show that extremely high levels of O2are possible in mats and biofilms without ebullition, and while maintaining very high photosynthetic activity.

Influence of oxide bond energies on the kinetics of chemical dissolution of anodic oxides on valve metals

1988 ◽  
Vol 18 (4) ◽  
pp. 532-537 ◽  
Author(s):  
A. G. Gad-Allah ◽  
H. A. Abd El-Rahman ◽  
M. M. Abou-Romia
Keyword(s):  
Chemical Dissolution ◽  
Bond Energies ◽  
Valve Metals ◽  
Kinetics Of
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