scholarly journals Hysteresis in the Active Oxidation of SiC

2019 ◽  
Vol 41 (42) ◽  
pp. 105-114
Author(s):  
Nathan Jacobson ◽  
Bryan J. Harder ◽  
Dwight D. Myers
Keyword(s):  
Active Oxidation

Active oxidation protection for ABM control surfaces

1971 ◽  
Author(s):  
D. CAWTHON ◽  
C. JOYNER, JR.
Keyword(s):  
Active Oxidation ◽  
Oxidation Protection ◽  
Control Surfaces

scholarly journals A CRYSTALLINE, ACTIVE OXIDATION PRODUCT OF α-CHYMOTRYPSIN

1951 ◽  
Vol 189 (2) ◽  
pp. 671-682 ◽  
Author(s):  
Eugene F. Jansen ◽  
A. Laurence Curl ◽  
A.K. Balls
Keyword(s):  
Oxidation Product ◽  
Active Oxidation

Use of Volume Element Methods to Understand Experimental Differences in Active/Passive Transitions and Active Oxidation Rates for SiC

2013 ◽  
Vol 96 (4) ◽  
pp. 1317-1323 ◽  
Author(s):  
Y. Kubota ◽  
H. Hatta ◽  
T. Yoshinaka ◽  
Y. Kogo ◽  
T. Goto ◽  
...  
Keyword(s):  
Volume Element ◽  
Active Oxidation ◽  
Oxidation Rates

scholarly journals THE FORMATION OF METHEMOGLOBIN BY STREPTOCOCCUS VIRIDANS

1916 ◽  
Vol 24 (4) ◽  
pp. 315-327 ◽  
Author(s):  
Francis G. Blake
Keyword(s):  
Blood Cells ◽  
Chemical Nature ◽  
Oxidation Process ◽  
Streptococcus Viridans ◽  
Bacterial Cells ◽  
Active Oxidation ◽  
Oxidation Processes ◽  
Reduction Processes ◽  
Methemoglobin Formation ◽  
Metabolic Activities

Cultures of Streptococcus viridans when brought into contact with red blood corpuscles have the power of transforming oxyhemoglobin into methemoglobin. The reaction occurs only in the presence of living streptococci when they are able to carry on their metabolic activities. The intensity of the reaction runs roughly parallel with the period of growth and multiplication of the bacteria and gradually diminishes and disappears as growth ceases. There is no apparent relation between the activity of a given strain of Streptococcus viridans in producing methemoglobin and its source or virulence. If the streptococci are suspended in salt solution they are unable to change oxyhemoglobin into methemoglobin unless some nutrient substance is present. Of the various nutrient substances tested dextrose is the most efficient in enabling the organisms to bring about the reaction. The reaction does not occur in the absence of oxygen, and is retarded by an excess of oxygen. Substances which tend to reduce the metabolic activities of the bacteria to a minimum exert an inhibitory action on methemoglobin formation. While not definitely proving it to be so, the results obtained in the above experiments strongly support the supposition that the reaction is not due to injurious substances produced by the bacteria or to products arising from the decomposition of the nutrient material present, but rather to the metabolic activities of the bacteria themselves when they are surrounded by environmental conditions which render growth and multiplication possible. The exact chemical nature of the change of oxyhemoglobin to methemoglobin is not known, but it is probably an oxidation process or a combination of reduction and oxidation processes, as pointed out by Heubner. As Cole has shown, the action of aminophenol is of great interest in this connection, in that it acts like a catalytic agent in being able to transform much more hemoglobin into methemoglobin than would be possible if the reaction were a simple molecular one. The metabolic activities of bacteria are largely in the nature of oxidation and reduction processes. The transformation of oxyhemoglobin into methemoglobin by streptococci of the viridans type, therefore, may be analogous to the action of such substances as aminophenol, and the reaction may be due to the active oxidation and reduction processes occurring in the neighborhood of the bacterial cells. The failure of the reaction to occur in the absence of oxygen and its retardation in the presence of an excess of oxygen, both with streptococci and with pneumococci (Cole) would seem to support this theory. Such results, however, may be due to the abnormal conditions surrounding the bacteria with consequent inhibition of their metabolic activities. Cole concluded as the result of his study of methemoglobin formation by pneumococci that since bacteria may injure red blood cells apparently by disturbances in oxidation in the immediate neighborhood of the organisms rather than by the production of a definite toxin, it is possible that bacteria may injure other tissue cells in a like manner and that the pathological effects produced by these bacteria may be explained on this basis. The experimental results recorded above have shown that the formation of methemoglobin by Streptococcus viridans in no way differs from its formation by pneumococci, and they lend support to the theory that bacteria may be injurious to tissues because of the disturbances in oxidation brought about by the metabolic activities of the organisms, especially those associated with growth and multiplication. It is believed that this theory may be particularly applicable to the pathological effects caused by Streptococcus vindans because the lesions produced by it, whether single or multiple, both in man and in experimental animals, are prone to be localized and associated with the actual presence of the streptococci in the lesions.

Char Oxidation Model Validation in Detailed Coal Simulations

1999 ◽  
Author(s):  
Stefan P. Domino ◽  
Philip J. Smith
Keyword(s):  
Coal Combustion ◽  
Unburned Carbon ◽  
Pulverized Coal Combustion ◽  
Active Oxidation ◽  
Data Set ◽  
Carbon Burnout ◽  
Oxidation Model ◽  
Simulation Results ◽  
Char Oxidation ◽  
Residual Weight

Abstract The controlling mechanisms governing the amount of unburned carbon in fly ash from practical pulverized coal combustion systems have been studied by incorporating elements of the carbon burnout kinetic model (CBK) proposed by Hurt et al. in a computational fluid dynamics based combustion, cfd, simulator. An experimental data set from The International Flame Research Foundation are compared to evaluate mechanistic variations in the carbon burnout processes. Simulation results comparing total exit LOI (defined as the residual weight of carbon in the ash) and centerline carbon burnout indicates that use of a char oxidation submodel, including the effects of a statistical reactivity distribution, thermal annealing of active oxidation sites and a developing ash film resistance layer, is necessary to predict experimentally measured exit LOI and centerline burnout profiles.

Electron-Rich Gold Clusters Stabilized by Poly(vinylpyridines) as Robust and Active Oxidation Catalysts

Langmuir ◽  
2020 ◽  
Vol 36 (27) ◽  
pp. 7844-7849
Author(s):  
Atsushi Matsuo ◽  
Shingo Hasegawa ◽  
Shinjiro Takano ◽  
Tatsuya Tsukuda
Keyword(s):  
Gold Clusters ◽  
Oxidation Catalysts ◽  
Active Oxidation

Acetogenesis does not replace ketogenesis in fasting piglets infused with hexanoate

1998 ◽  
Vol 274 (6) ◽  
pp. E963-E970 ◽  
Author(s):  
Sean H. Adams ◽  
Jack Odle
Keyword(s):  
Fatty Acid ◽  
Continuous Infusion ◽  
Ketone Bodies ◽  
Negative Impact ◽  
Physiological Role ◽  
Active Oxidation ◽  
Acetate Concentration ◽  
Physiological Relevance ◽  
Mitochondrial Fatty Acid

The current studies were performed to better understand the physiological relevance of acetate in the poorly ketogenic piglet and to determine if endogenous acetogenesis rises with increased mitochondrial fatty acid β-oxidation, analogous to ketogenesis. Plasma acetate concentration values in newborn, fasted, or suckled piglets (230–343 μM) were at least 10-fold higher than the ketone bodies, a pattern opposite to that in 24- to 48-h suckled rats (77–175 μM). Employing continuous infusion techniques with sodium [3H]acetate tracer in fasting ∼40-h-old piglets, acetate rate of appearance (Ra) was found to be 34 ± 4 μmol ⋅ min−1 ⋅ kg body wt−1. This basal Ra was double that observed in animals coinfused with sodium [1-14C]hexanoate ( P < 0.001), despite active oxidation of the latter as determined by14CO2production. Active acetogenesis in vivo and relatively abundant acetate in piglet blood are consistent with the hypothesis that acetate plays an important physiological role in piglets. However, the negative impact of hexanoate oxidation upon acetate Ra and the lack of significant changes in circulating acetate in newborn, suckled, and fasted piglets draws into question the extent of analogy between acetogenesis and ketogenesis in vivo.

Active Oxidation and Fume Formation from Liquid SiMn

2016 ◽  
pp. 77-84
Author(s):  
Ida Kero ◽  
Gabriella Tranell
Keyword(s):  
Active Oxidation

scholarly journals Improved oxidation of aromatic and aliphatic hydrocarbons using rate enhancing variants of P450Bm3 in combination with decoy molecules

2016 ◽  
Vol 52 (5) ◽  
pp. 1036-1039 ◽  
Author(s):  
Samuel D. Munday ◽  
Osami Shoji ◽  
Yoshihito Watanabe ◽  
Luet-Lok Wong ◽  
Stephen G. Bell
Keyword(s):  
Fatty Acids ◽  
Aliphatic Hydrocarbons ◽  
Product Selectivity ◽  
Active Oxidation ◽  
Highly Active

The addition of perfluorinated fatty acids to the rate accelerating KT2 mutant of P450Bm3 resulted in the highly active oxidation of cyclohexane and benzenes whilst maintaining the product selectivity.

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