Results 11 to 20 of about 22,867 (163)

Enzymatic Single-Molecule Kinetic Isotope Effects [PDF]

Journal of the American Chemical Society, 2013
Ensemble-based measurements of kinetic isotope effects (KIEs) have advanced physical understanding of enzyme-catalyzed reactions, but controversies remain. KIEs are used as reporters of rate-limiting H-transfer steps, quantum mechanical tunnelling, dynamics and multiple reactive states.
Pudney, Christopher R., Lane, Richard S K, Fielding, Alistair J., Magennis, Steven W., Hay, Sam, Scrutton, Nigel S.   +5 more
openaire   +4 more sources

Strontium isotope effect on Solid-Liquid extraction system using a polymer resin with 2.2.2-Cryptand anchor groups [PDF]

مجله علوم و فنون هسته‌ای, 2020
The chemical isotope exchange with macrocyclic polyethers is one of the relatively new methods for isotope separation. These separations are based on the phenomenon of isotope effect, in which the kinetic and the stability of the complex formation ...
E. Zolfonoun
doaj   +1 more source

Isotope effect in the formation of H₂ from H₂CO studied at the atmospheric simulation chamber SAPHIR [PDF]

Atmospheric Chemistry and Physics, 2010
Formaldehyde of known, near-natural isotopic composition was photolyzed in the SAPHIR atmosphere simulation chamber under ambient conditions. The isotopic composition of the product H2 was used to determine the isotope effects in formaldehyde photolysis.
R. Koppmann, E. Schlosser, R. Tillmann, T. Brauers, H. Spahn, B. Bohn, R. Wegener, S. Walter, T. Röckmann, F. Rohrer   +9 more
doaj   +1 more source

Nitrogen Isotope Fractionation During Archaeal Ammonia Oxidation: Coupled Estimates From Measurements of Residual Ammonium and Accumulated Nitrite

Frontiers in Microbiology, 2020
The naturally occurring nitrogen (N) isotopes, 15N and 14N, exhibit different reaction rates during many microbial N transformation processes, which results in N isotope fractionation. Such isotope effects are critical parameters for interpreting natural
Maria Mooshammer, Ricardo J. E. Alves, Barbara Bayer, Michael Melcher, Michaela Stieglmeier, Lara Jochum, Simon K.-M. R. Rittmann, Margarete Watzka, Christa Schleper, Gerhard J. Herndl, Gerhard J. Herndl, Wolfgang Wanek   +11 more
doaj   +1 more source

Kinetic Isotope Effects in Asymmetric Reactions [PDF]

Chemistry – A European Journal, 2010
AbstractKinetic isotope effects are exquisitely sensitive probes of transition structure. As such, kinetic isotope effects offer a uniquely useful probe for the symmetry‐breaking process that is inherent to stereoselective reactions. In this Concept article, we explore the role of steric and electronic effects in stereocontrol, and we relate these ...
Thomas, Giagou, Matthew P, Meyer
openaire   +2 more sources

A kinetic chemistry tagging technique and its application to modelling the stable isotopic composition of atmospheric trace gases [PDF]

Geoscientific Model Development, 2010
Isotope composition, in many cases, holds unique information on the sources, chemical modification and sinks of atmospheric trace gases. Vital to the interpretation and use of an increasing number of isotope analyses is appropriate modelling.
S. Gromov, P. Jöckel, R. Sander, C. A. M. Brenninkmeijer   +3 more
doaj   +1 more source

Kinetic 15N-isotope effects on algal growth [PDF]

Scientific Reports, 2017
AbstractStable isotope labeling is a standard technique for tracing material transfer in molecular, ecological and biogeochemical studies. The main assumption in this approach is that the enrichment with a heavy isotope has no effect on the organism metabolism and growth, which is not consistent with current theoretical and empirical knowledge on ...
Andriukonis, Eivydas, Gorokhova, Elena
openaire   +3 more sources

Shifts in rotifer life history in response to stable isotope enrichment: testing theories of isotope effects on organismal growth [PDF]

Royal Society Open Science, 2017
In ecology, stable isotope labelling is commonly used for tracing material transfer in trophic interactions, nutrient budgets and biogeochemical processes.
Elena Gorokhova
doaj   +1 more source

Mechanism of the Reaction of lron(I) Ions with Neutral 4-Octyne in the Gas Phase – Experimental Evidence for an irreversible β-Hydrogen Transfer

CHIMIA, 1986
Experimental evidence is presented that β-hydrogen transfer, to generate bis-olefin Fe⊕ complexes from bare Fe⊕ and 2H-labeled 4-octynes is neither reversible nor associated with a primary kinetic isotope effect; unimolecular loss of labeled ethylene ...
Christian Schulze, Thomas Weiske, Helmut Schwarz   +2 more
doaj   +1 more source

Experimental Determination of Primary and Secondary Deuterium Isotope Effects in the FeI-Mediated CH/CC Bond Activation of [Fe(4-Heptanone)]⊕ Complexes in the Gas Phase

CHIMIA, 1989
The gas-phase behaviour of [Fe(4-heptanone)]⊕ is in several aspects quite distinct from that of other Fe⊕ complexes as far as kinetic details of the individual steps of CH/CC bond activation are concerned.
Detlef Schröder, Helmut Schwarz
doaj   +1 more source