An Alternative Mechanism for the Production of Hydroxyl Radicals by Stimulated Neutrophils

1982 ◽  
pp. 423-427 ◽  
Author(s):  
M. J. Okolow-Zubkowska ◽  
H. A. O. Hill
Keyword(s):  
Hydroxyl Radicals ◽  
Alternative Mechanism

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

Can Mouse-tracking Reveal Attribute Processing Speeds in Dietary Self-control? Commentary on Sullivan et al. (2015) and Lim et al. (2018) with A Simulation Study

2018 ◽  
Author(s):  
Chao Zhang ◽  
Martijn Willemsen ◽  
Daniel Lakens
Keyword(s):  
Simulation Study ◽  
Processing Speed ◽  
Empirical Data ◽  
Self Control ◽  
Alternative Mechanism ◽  
Mouse Tracking ◽  
Tracking Method ◽  
Cognitive Mechanism ◽  
Speed Difference ◽  
Original Hypothesis

In this commentary, we re-examine the use of a mouse-tracking method for revealing attribute processing speed difference in dietary self-control (Sullivan et al. 2015; Lim et al., 2018). Through re-analyses of Sullivan et al. (2015)’s data and a simulation study, it can be shown that the attribute-angle correlations in the empirical data, which were used to estimate processing speeds, are attributed primarily to their common correlations with choice. The simulation study further suggests that when we account for the choice-mediated attribute-angle correlations, the data patterns used for supporting the original hypothesis can be produced by implementing a plausible alternative mechanism unrelated to processing speeds. The mouse-tracking method therefore fails to provide clear evidence for processing speed difference as a cognitive mechanism of self-control. Researchers should be cautious when using the mouse-tracking method to estimate attribute processing speeds.

Trihalomethane Formation Potential and Disinfection

1992 ◽  
Vol 27 (1) ◽  
pp. 185-202
Author(s):  
C.R. Erland Jansson
Keyword(s):  
Hydroxyl Radicals ◽  
Giardia Lamblia ◽  
Test Results ◽  
Formation Potential ◽  
Trihalomethane Formation Potential ◽  
Resistant Species ◽  
Low Levels ◽  
High Concentrations ◽  
Operational Data ◽  
Surface Water Supply

Abstract The UVOX process was developed to reduce the high concentrations of trihalomethanes, a potentially hazardous disinfection by-product found in a surface water supply for a community in northeastern Saskatchewan. Pilot plant tests were conducted at a throughput of 1.25 l/s utilizing UV to produce hydroxyl radicals from photolysis of H2O2 with air cooled UV units. These tests continued through 1985 andl986 to provide operational data for all seasons of the year. Test results indicated that the UVOX process was effective in reducing trihalomethane formation potential to very low levels. Recent concerns have also centred on the biocidal effectivenesss of disinfectants, particularly when applied to inactivation of resistant species of microogranisms, such as the cysts of Giardia lamblia. The UVOX process in a single pass configuration slightly enhanced the ability of UV to inactivate Giardia cysts.

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