Rate of14N2 desorption from the surfaces of nitrides in the presence and absence of15N2 in the gas phase

1985 ◽  
Vol 29 (2) ◽  
pp. 433-441 ◽  
Author(s):  
V. I. Sobolev ◽  
G. I. Panov ◽  
A. S. Kharitonov
Keyword(s):  
Gas Phase ◽  
Presence And Absence

scholarly journals Pressure dependent aerosol formation from the cyclohexene gas-phase ozonolysis in the presence and absence of sulfur dioxide: a new perspective on the stabilisation of the initial clusters

2012 ◽  
Vol 14 (33) ◽  
pp. 11695 ◽  
Author(s):  
Philip Thomas Michael Carlsson ◽  
Janina Elisabeth Dege ◽  
Claudia Keunecke ◽  
Bastian Christopher Krüger ◽  
Jan Lennard Wolf ◽  
...  
Keyword(s):  
Sulfur Dioxide ◽  
Gas Phase ◽  
Aerosol Formation ◽  
Presence And Absence ◽  
New Perspective

Reactions of thiyl radicals. V. The gas phase photolysis of methyl disulfide and ethyl disulfide mixtures in the presence of ethylene

1968 ◽  
Vol 46 (14) ◽  
pp. 2462-2464 ◽  
Author(s):  
P. M. Rao ◽  
A. R. Knight
Keyword(s):  
Gas Phase ◽  
Methyl Ethyl ◽  
Thiyl Radicals ◽  
Disulfide Formation ◽  
Presence And Absence ◽  
Low Efficiency

The gas phase photolysis of methyl disulfide and ethyl disulfide and their mixtures, in the presence and absence of ethylene, has been studied at 25 °C and λ = 2300–2800 Å. The pure substrates give predominantly the corresponding thiol, whereas co-photolysis yields methyl ethyl disulfide in appreciably larger yields.When ethylene is added, the substrates individually show a reduction in RSH rate and the formation of relatively small amounts of sulfides. In their co-photolysis, added C2H4 does not appreciably alter the rate of methyl ethyl disulfide formation, indicating a low efficiency of RS scavenging by the olefin in this system.Isopropanol and 2,3-dimethyl butane do not increase the thiol yield from the pure substrates.

Behaviour of the surface hydroxide groups of exfoliated kaolinite in the gas phase and during water adsorption

2016 ◽  
Vol 45 (6) ◽  
pp. 2523-2535 ◽  
Author(s):  
Attila Táborosi ◽  
Róbert K. Szilágyi
Keyword(s):  
Gas Phase ◽  
Crystalline Phase ◽  
Water Adsorption ◽  
Chemical Environment ◽  
Presence And Absence

New insights: surface hydroxide groups of the O-sheet and bridging oxide anions of the T-sheet adopt very different orientations in the exfoliated kaolinite from those in the crystalline phase as a function of the presence and absence of an external chemical environment that significantly influences clay reactivity.

Products of the gas-phase reactions of o-, m- and p-xylene with the OH radical in the presence and absence of NOx

1997 ◽  
Vol 93 (16) ◽  
pp. 2847-2854 ◽  
Author(s):  
Eric S. C. Kwok ◽  
Sara M. Aschmann ◽  
Roger Atkinson ◽  
Janet Arey
Keyword(s):  
Gas Phase ◽  
Oh Radical ◽  
Gas Phase Reactions ◽  
Presence And Absence

scholarly journals The formation of SOA and chemical tracer compounds from the photooxidation of naphthalene and its methyl analogs in the presence and absence of nitrogen oxides

2012 ◽  
Vol 12 (5) ◽  
pp. 12163-12201 ◽  
Author(s):  
T. E. Kleindienst ◽  
M. Jaoui ◽  
M. Lewandowski ◽  
J. H. Offenberg ◽  
K. S. Docherty
Keyword(s):  
Nitrogen Oxides ◽  
Gas Phase ◽  
Phthalic Anhydride ◽  
Mass Fraction ◽  
Phthalic Acid ◽  
Organic Aerosol ◽  
Primary Sources ◽  
Smog Chamber ◽  
Mass Fractions ◽  
Presence And Absence

Abstract. Laboratory smog chamber experiments have been carried out to investigate secondary organic aerosol (SOA) formation from the photooxidation of naphthalene and its methyl analogs, 1- and 2-methylnaphthalene (1-MN and 2-MN, respectively). Laboratory smog chamber irradiations were conducted in a flow mode to ensure adequate collection of the aerosol at reasonably low reactant concentrations and in the presence and absence of nitrogen oxides. Phthalic acid and methyl analogs were identified following BSTFA derivatization of the aerosol extract. These compounds were examined to determine whether they could serve as reasonable molecular tracers to estimate the contributions of these precursors to ambient PM2.5. Measurements were also made to determine aerosol parameters from secondary organic aerosol from naphthalene, 1-MN, and 2-MN. A mass fraction approach was used to establish factors which could be applied to phthalic acid concentrations in ambient aerosols, assuming a negligible contribution from primary sources. In addition, the hydrolysis of phthalic anhydride was tested and found to represent a moderate filter artifact in side-by-side filter measurements with and without in-line denuders. This study also provided the opportunity to examine numeric differences using authentic standards for phthalic acid compared to surrogate standards. While the mass fraction based on a surrogate compounds was somewhat lower, the differences are largely unimportant. For naphthalene, mass fractions of 0.023 and 0.019 were determined in the presence and absence of nitrogen oxides, respectively, based on the phthalic acid standards. The mass fractions determined from the laboratory data were then applied to ambient samples where phthalic acid was found and expressed "as naphthalene" since phthalic acid was found to be produced in the particle phase from other PAHs tested. The mass fraction values were applied to samples taken during the 2005 SOAR Study in Riverside, CA and 2010 CalNex Study in Pasadena. In both studies an undetermined isomer of methylphthalic acid was detected in addition to phthalic acid. Laboratory experiment retention times and mass spectra suggest that the major precursor for this compound is 2-MN. For the CalNex Study, SOC values for the gas-phase PAHs (as naphthalene) were found to range from below the detection limit to 20 ng C m−3 which together with the laboratory mass fraction data suggests an upper limit of 1 μg m−3 for SOA due to PAHs. Temporal data over the course of the one-month CalNex study suggest that primary sources of phthalic acid were probably negligible during this study period. However, the values must still be considered upper limits given a potential gas-phase hydrolysis reaction or uptake of phthalic anhydride (subsequently hydrolyzed) onto the collection medium.

Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

1968 ◽  
Vol 26 ◽  
pp. 292-293
Author(s):  
Richard E. Hartman ◽  
Roberta S. Hartman ◽  
Peter L. Ramos
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Gas Phase ◽  
Absolute Temperature ◽  
Residual Gas ◽  
Gas Reactions ◽  
Image Position ◽  
The Right ◽  
Water Gas ◽  
Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

Integration of Core-Edge Spectroscopy Methods for the Study of Polymers

1996 ◽  
Vol 54 ◽  
pp. 154-155
Author(s):  
E. G. Rightor
Keyword(s):  
Excited State ◽  
Polymer Blends ◽  
Gas Phase ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Electronic States ◽  
Core Electron ◽  
Bulk Solids ◽  
Development Application

Core edge spectroscopy methods are versatile tools for investigating a wide variety of materials. They can be used to probe the electronic states of materials in bulk solids, on surfaces, or in the gas phase. This family of methods involves promoting an inner shell (core) electron to an excited state and recording either the primary excitation or secondary decay of the excited state. The techniques are complimentary and have different strengths and limitations for studying challenging aspects of materials. The need to identify components in polymers or polymer blends at high spatial resolution has driven development, application, and integration of results from several of these methods.

Effects of Noise and Increased Vocal Intensity on Stuttering

1977 ◽  
Vol 20 (2) ◽  
pp. 233-240 ◽  
Author(s):  
Sharon F. Garber ◽  
Richard R. Martin
Keyword(s):  
Normal Level ◽  
Auditory Feedback ◽  
Concomitant Increase ◽  
Vocal Intensity ◽  
Presence And Absence

The present study was designed to assess the effects of increased vocal level on stuttering in the presence and absence of noise, and to assess the effects of noise on stuttering with and without a concomitant increase in vocal level. Accordingly, eight adult stutterers spoke in quiet with normal vocal level, in quiet with increased vocal level, in noise with normal level, and in noise with increased level. All subjects reduced stuttering in noise compared with quiet conditions. However, there was no difference in stuttering when subjects spoke with normal compared with increased vocal level. In the present study, reductions in stuttering under noise could not be explained by increases in vocal level. It appears, instead, that reductions in stuttering were related to a decrease in auditory feedback. The condition which resulted in the largest decrease in auditory feedback, speaking in noise with a normal level, also resulted in the largest decrease in stuttering.

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