Concept

Isotope

Publications associées (245)

Three applications of path integrals: equilibrium and kinetic isotope effects, and the temperature dependence of the rate constant of the [1,5] sigmatropic hydrogen shift in (Z)-1,3-pentadiene

Recent experiments have confirmed the importance of nuclear quantum effects even in large biomolecules at physiological temperature. Here we describe how the path integral formalism can be used to describe rigorously the nuclear quantum effects on equilibr ...

Springer Verlag2010

Diffusion-Weighted Spectroscopy: A Novel Approach to Determine Macromolecule Resonances in Short-Echo Time H-1-MRS

Rolf Gruetter, Cristina Ramona Cudalbu, Nicolas Kunz

Quantification of short-echo time proton magnetic resonance spectroscopy results in >18 metabolite concentrations (neurochemical profile). Their quantification accuracy depends on the assessment of the contribution of macromolecule (MM) resonances, previou ...

Wiley-Blackwell2010

Apparent transverse relaxation rates in systems with coupled carbon-13 spins

Geoffrey Bodenhausen, Nicolas Aeby

In systems with homonuclear scalar couplings, the envelopes of spin echoes obtained with simple refocusing pulses or trains of such pulses are normally modulated so that it is difficult to extract transverse relaxation rates. It has been shown recently tha ...

Royal Society of Chemistry2010

Validation of a nanoliquid chromatography-tandem mass spectrometry method for the identification and the accurate quantification by isotopic dilution of glutathionylated and cysteinylated precursors of 3-mercaptohexan-1-ol and 4-mercapto-4-methylpentan-2-one in white grape juices

Marc Moniatte, Jérôme Vialaret

A rapid nanoLc-MS/MS method was developed and validated for the simultaneous determination of glutathionylated and cysteinylated precursors of 3-mercapto-hexan-1-ol (3MH) and 4-methyl-4-mercaptopentan-2-one in grape juice using stable isotope dilution assa ...

2010

Proton Transfer Studied Using a Combined Ab Initio Reactive Potential Energy Surface with Quantum Path Integral Methodology

Jiri Vanicek, Wei Zhang

The rates of intramolecular proton transfer are calculated on a full-dimensional reactive electronic potential energy surface that incorporates high-level ab initio calculations along the reaction path and by using classical transition state theory, path-i ...

2010

Analysis of labelled compounds by mass spectroscopy in the presence of heavy isotopes at natural abundance: the NAIC program

A program is described, which allows the intensity contributions from naturally occurring heavy isotopes to be eliminated from the mass spectrometric ions of an artificially labelled compound. This allows the accurate measurement of the isotopomer distribu ...

2009

Effect of environmental conditions and skeletal ultrastructure on the Li isotopic composition of scleractinian corals

Anders Meibom

The lithium isotope compositions (Li-7/Li-6) and Li/Ca ratios of shallow-water and deep-sea corals (Porites lutea, Cladocora caespitosa, Lophelia pertusa and Desmophyllum cristagalli) were measured using a Cameca ims 1270 ion microprobe. The two C. caespit ...

2009

Quantification of biodegradation for o-xylene and naphthalene using first order decay models, Michaelis-Menten kinetics and stable carbon isotopes

At a former wood preservation plant severely contaminated with coal tar oil, in situ bulk attenuation and biodegradation rate constants for several monoaromatic (BTEX) and polyaromatic hydrocarbons (PAH) were determined using (1) classical first order deca ...

2009

Pristine extraterrestrial material with unprecedented nitrogen isotopic variation

Anders Meibom

Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, high ...

2009

Diffusion Coefficients of Biomolecules Using Long-Lived Spin States

Geoffrey Bodenhausen, Paul Romeo Vasos, Riddhiman Sarkar, Puneet Ahuja

We report the first observation of long-lived states (LLS) having lifetimes TLLS that exceed the corresponding spin−lattice relaxation times T1 by more than a factor 6 in a protein. Slow diffusion coefficients characteristic of large biomolecules can be de ...

2009

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