Results 251 to 260 of about 9,679,616 (302)

Isotope Effect and Isotope Separation: A Chemist's View.

Journal of Nuclear Science and Technology, 2002
What causes the isotope effects (IE)? This presentation will be centered around the equilibrium isotope effects due to the differences in the nuclear masses. The occurrence of the equilibrium constant, K, of isotope exchange reactions which differ from the values predicted by the classical theory of statistical mechanics, Kcl , is explored.
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Isotope Effects in Plasmonic Photosynthesis

Angewandte Chemie, 2020
AbstractThe photoexcitation of plasmonic nanoparticles has been shown to drive multistep, multicarrier transformations, such as the conversion of CO2 into hydrocarbons. But for such plasmon‐driven chemistry to be precisely understood and modeled, the critical photoinitiation step in the reaction cascade must be identified.
Sungju Yu, Prashant K. Jain
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The effect of the thermodynamic isotope effect on the distribution of isotopic molecules

Bulletin of the Academy of Sciences of the USSR Division of Chemical Science, 1961
1. The thermodynamic isotope effect (TIE) may cause the distribution of isotopic molecules to differ substantially from the statistical distribution, especially in the case of light elements. 2. A method is indicated for setting up a system of algebraic equations, the solution of which makes it possible to calculate the concentration of ...
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Isotope effects on isotope effects: equilibrium nitrogen isotope effects on the basicity of pyridine in protium and deuterium oxides

The Journal of Physical Chemistry, 1989
The {sup 14}N/{sup 15}N isotope effect on the pK{sub a} of pyridinium ion is 18% larger in D{sub 2}O than in H{sub 2}O: pK{sub a}{sup 14} {minus} pK{sub a}{sup 15} = {minus}0.0090{sub 7} {plus minus} 0.0001{sub 6} in H{sub 2}O and {minus}0.0107{sub 2} {plus minus} 0.0001{sub 5} in D{sub 2}O.
Joseph L. Kurz, Moheb M. Nasr
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Deuterium Isotope Effect on Carbon Isotope Fractionation in Photosynthesis

Science, 1967
Plants grown in D 2 O show a decreased tendency to fractionate carbon-13 during photosynthetic incorporation of carbon dioxide. The isotopic ratio C 13 /C 12 of the tissues of deuterated plants appears to be proportional to the deuterium content of the tissue.
R A, Uphaus, J J, Katz
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Isotope Effect in Superconducting Fullerenes

Science, 1992
The effect of isotopic substitution on the superconducting transition temperature, T c , in alkali-doped C 60 has been examined. Paradoxically, it is found that a substantial decrease in T c with the increasing isotopic mass is possible even ...
S, Chakravarty, S A, Kivelson, M I, Salkola, S, Tewari   +3 more
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Isotope effects on the crotonase reaction

Biochemistry, 1989
The primary, alpha-secondary, beta-secondary, and beta'-secondary deuterium and primary 18O kinetic isotope effects on V/K for the dehydration of [(3S)-3-hydroxybutyryl]pantetheine by bovine liver crotonase (enoyl-CoA hydratase, EC 4.2.1.17) have been determined by the equilibrium perturbation method.
B J, Bahnson, V E, Anderson
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Observation of Isotope Effects in Sonoluminescence

Physical Review Letters, 1995
The spectrum of sonoluminescence emitted by single bubbles of H{sub 2}, D{sub 2}, He{sup 3}, and He{sup 4} trapped in H{sub 2}O and D{sub 2}O has been measured. We find that heavy water has a dramatic effect on the spectrum of hydrogenic gases, yielding a blackbody-type spectrum with a spectral peak at about 400 nm.
, Hiller, , Putterman
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Measurement of Enzyme Isotope Effects

2017
Enzyme isotope effects, or the kinetic effects of "heavy" enzymes, refer to the effect of isotopically labeled protein residues on the enzyme's activity or physical properties. These effects are increasingly employed in the examination of the possible contributions of protein dynamics to enzyme catalysis.
Svetlana A, Kholodar, Ananda K, Ghosh, Amnon, Kohen   +2 more
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Isotope Effects on Nuclear Shielding

Progress in Nuclear Magnetic Resonance Spectroscopy, 1984
Publisher Summary Isotope effects have been known for a long time and an excellent review covering the early reports exists. The magnitude of the isotope shift is generally dependent on how remote the isotope substitution is from the nucleus under observation.
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