نتایج جستجو برای: 2h isotope shift
تعداد نتایج: 178729 فیلتر نتایج به سال:
Carbon (?13C) and hydrogen (?2H) compound-specific isotope analyses on sedimentary hydrocarbons are widely used for ecological reconstructions oil-source rock or oil-oil correlations. However, the effects of thermal alteration isotopic composition not fully understood, potentially imparting a bias interpretation older more mature sequences. We measured ?13C ?2H n-alkanes in 23 extracted bitumen...
deuterium substitution on two ortho-substituted-och2-fragments in nitro-benzo-9-crown-3 induces low frequency shifts, positive mndcj, in all 13c nmr resonances which is an indication of the increased shielding in this crown ether. the magnitude of these shifts vary from 15dc7=716 to 54dc3=15 ppb for c7 and c3 cd3cocd3, and c6d6 on mndcj values were investigated. the mndcj values depended more o...
As has been detailed in [1, 2], dielectronic recombination (DR) of few-electron heavy-ions is a promising novel approach to study nuclear properties like charge radii and hyperfine effects. Isotope shift measurements of highly charged ions by means of DR complement nicely optical (laser) spectroscopic techniques in neutral atoms or moderately charged ions since the interpretation of the energy ...
1. alpha-Deuterium kinetic isotope effects on the phosphorolysis of inosine catalysed by Escherichia coli purine nucleoside phosphorylase were measured by the equilibrium-perturbation technique, by using the change in absorbance at 250 nm (approx. 20%). 2. Values of 2H(V/K) of 1.13(9) at pH 5.0, 1.10(5) at pH 6.1, 1.09(4) at pH 7.3, 1.08 at pH 8.4 and 1.16(4) at pH 9.4 were obtained. 3. These a...
Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional ...
Protein turnover in living systems has been measured with the use of stable isotope labeled tracers for over half a century [1]. Recent advances, in mass spectrometry, sample preparation and separation sciences have made it possible for this approach to become applicable at a global proteomics level, permitting analysis of the turnover of many proteins instead of single proteins or an aggregate...
Darwin-Foldy nuclear-size corrections in electronic atoms and nuclear radii are discussed from the nuclear-physics perspective. Interpretation of precise isotope-shift measurements is formalism dependent, and care must be exercised in interpreting these results and those obtained from relativistic electron scattering from nuclei. We strongly advocate that the entire nuclear-charge operator be u...
The most notable trend in the sedimentary iron isotope record is a shift at the end of the Archean from highly variable δ56 Fe values with large negative excursions to less variable δ56 Fe values with more limited negative values. The mechanistic explanation behind this trend has been extensively debated, with two main competing hypotheses: (i) a shift in marine redox conditions and the transit...
effects on chemical shift of hydrogen bonded compounds in solution. For recent more complete reviews see [7, 8, 25] and for isotope effects primarily on intermolecular hydrogen bonding and in the solid state the papers by the Limbach group [3, 4, 33, 34]. The paper will concentrate on intrinsic isotope effects and not so much on equilibrium ones. The review will also concentrate on situations w...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید