An Interpretation of the Vapor Phase Second Virial Coefficient Isotope Effect:  Correlation of Virial Coefficient and Vapor Pressure Isotope Effects

2001 ◽  
Vol 105 (40) ◽  
pp. 9284-9297 ◽  
Author(s):  
W. Alexander Van Hook ◽  
Luis Paulo N. Rebelo ◽  
Max Wolfsberg
Keyword(s):  
Vapor Pressure ◽  
Isotope Effect ◽  
Vapor Phase ◽  
Virial Coefficient ◽  
Isotope Effects ◽  
Second Virial Coefficient

Comments on H/D Isotope Effects on Polarizabilities of Small Molecules. Correlation with Virial Coefficient, Molar Volume, and Electronic Second Moment Isotope Effects

1994 ◽  
Vol 49 (4-5) ◽  
pp. 563-577 ◽  
Author(s):  
W. Alexander Van Hook ◽  
Max Wolfsberg
Keyword(s):  
Refractive Index ◽  
Molar Volume ◽  
Isotope Effect ◽  
Virial Coefficient ◽  
Isotope Effects ◽  
Thermodynamic Activity ◽  
Vibrational Amplitude ◽  
Second Moment ◽  
Index Data ◽  
Refractive Index Data

Abstract Literature data on H/D isotope effects on polarizability are reviewed. An argument based on perturbation theory correlates the isotopic differences with electronic transition moments via vibrational averaging. The contribution of the second moment isotope effect is especially important. The approach is first illustrated with a calculation on H2/D2 and then employed to correlate differential refractive index data on about twenty other H/D isotopic pairs. A table of bond polarizability isotope effects is presented which permits the estimation of polarizability isotope effects for various kinds of H/D substituted compounds. Coupling these results with known isotope effects on vibrational amplitude permits calculation of vapor phase virial coefficient isotope effects, while combina­tion with refractive index data on liquids yields reasonable values for the sum of the isotope effects on molar volume and electronic second moment. However the quantitative correlation of the polarizability isotope effect with isotope effects on vapor pressure or thermodynamic activity is less direct.

Molar Mass and Second Virial Coefficient of Polyethylene Glycol by Vapor Pressure Osmometry

2015 ◽  
Vol 92 (12) ◽  
pp. 2157-2160 ◽  
Author(s):  
Jeffrey J. Schwinefus ◽  
Caleb Checkal ◽  
Brian Saksa ◽  
Nadia Baka ◽  
Kalpit Modi ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Vapor Pressure ◽  
Virial Coefficient ◽  
Molar Mass ◽  
Second Virial Coefficient ◽  
Vapor Pressure Osmometry

Interpretation of Preferential Adsorption Using Random Phase Approximation Theory

1995 ◽  
Vol 60 (10) ◽  
pp. 1641-1652 ◽  
Author(s):  
Henri C. Benoît ◽  
Claude Strazielle
Keyword(s):  
Approximation Theory ◽  
Random Phase Approximation ◽  
Virial Coefficient ◽  
Random Phase ◽  
Second Virial Coefficient ◽  
Solvent Mixture ◽  
Gyration Radius ◽  
Thermodynamic Quantities ◽  
Phase Approximation ◽  
Preferential Adsorption

It has been shown that in light scattering experiments with polymers replacement of a solvent by a solvent mixture causes problems due to preferential adsorption of one of the solvents. The present paper extends this theory to be applicable to any angle of observation and any concentration by using the random phase approximation theory proposed by de Gennes. The corresponding formulas provide expressions for molecular weight, gyration radius, and the second virial coefficient, which enables measurements of these quantities provided enough information on molecular and thermodynamic quantities is available.

scholarly journals Nitrogen isotope effects can be used to diagnose N transformations in wastewater anammox systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paul M. Magyar ◽  
Damian Hausherr ◽  
Robert Niederdorfer ◽  
Nicolas Stöcklin ◽  
Jing Wei ◽  
...  
Keyword(s):  
Isotope Effect ◽  
Isotope Composition ◽  
Isotope Effects ◽  
Nitrogen Isotope ◽  
Anammox Bacteria ◽  
Ammonium Oxidation ◽  
Experimental Conditions ◽  
N Transformations ◽  
Natural Systems ◽  
Inverse Isotope Effect

AbstractAnaerobic ammonium oxidation (anammox) plays an important role in aquatic systems as a sink of bioavailable nitrogen (N), and in engineered processes by removing ammonium from wastewater. The isotope effects anammox imparts in the N isotope signatures (15N/14N) of ammonium, nitrite, and nitrate can be used to estimate its role in environmental settings, to describe physiological and ecological variations in the anammox process, and possibly to optimize anammox-based wastewater treatment. We measured the stable N-isotope composition of ammonium, nitrite, and nitrate in wastewater cultivations of anammox bacteria. We find that the N isotope enrichment factor 15ε for the reduction of nitrite to N2 is consistent across all experimental conditions (13.5‰ ± 3.7‰), suggesting it reflects the composition of the anammox bacteria community. Values of 15ε for the oxidation of nitrite to nitrate (inverse isotope effect, − 16 to − 43‰) and for the reduction of ammonium to N2 (normal isotope effect, 19–32‰) are more variable, and likely controlled by experimental conditions. We argue that the variations in the isotope effects can be tied to the metabolism and physiology of anammox bacteria, and that the broad range of isotope effects observed for anammox introduces complications for analyzing N-isotope mass balances in natural systems.

Vapor-Phase Thermal Conductivity, Vapor Pressure, and Liquid Density of R365mfc

2002 ◽  
Vol 47 (3) ◽  
pp. 554-558 ◽  
Author(s):  
Isabel M. Marrucho ◽  
Nelson S. Oliveira ◽  
Ralf Dohrn
Keyword(s):  
Thermal Conductivity ◽  
Vapor Pressure ◽  
Vapor Phase ◽  
Liquid Density
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