Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 9281486

Multiple nonlinear stimulated echoes.

I Ardelean·R Kimmich·S Stapf·D E Demco
View original source ↗Export metadata ↓

Abstract

Three-pulse sequences in the presence of magnetic field gradients at high magnetic fields produce multiple nonlinear stimulated echoes (NOSE) at times ntau1 after the third pulse, where n is an integer and tau1 the interval between the first two pulses. These phenomena are due to the demagnetizing field produced by the spatial modulation of the nuclear magnetization arising in the sample after the first two pulses. The theory is presented and compared with experiments. The dependence of the NOSE amplitudes on the flip angles and on the pulse intervals is described. Implications for multidimensional NMR experiments based on sequences of three or more pulses in the presence of field gradients are discussed.

Explore related subjects

DimethylpolysiloxanesMagnetic Resonance SpectroscopySiliconesWetting AgentsJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

I Ardelean, R Kimmich, S Stapf, D E Demco. 1997. Multiple nonlinear stimulated echoes.. https://doi.org/10.1006/jmre.1997.1197

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Study of on-line monitoring of lactate based on optical fibre sensor and in-channel mixing mechanism.

A PDMS-based microfluidic device with integrated optical fibres was developed for online monitoring of lactate. The detection is based on the optical adsorption of the colour solution formed by in-channel mixing of sample and reagent solutions. Computational Fluid Dynamics (CFD) simulation and kinetic study of the colour development were conducted to determine the minimum channel length and optimum residential time for homogenous mixing and maximum optical adsorption respectively. The system was proved to be able to detect lactate with good linearity (R(2)=0.98), response time of about 130 s and estimated limitation of detection (LOD) of 0.52 mM (about 47 mg/L), which is sufficient for a general online lactate detection. Due to the miniaturization of sensing system and micro-scale mixing, higher detection sensitivity (0.15 V/mM) can be realized than the mixing in lab-scale equipments (0.08 V/mM).

Dimethylpolysiloxanes↗
PubMed2006

Glass-fiber reinforced poly(acrylate)-based sorptive materials for the enrichment of organic micropollutants from aqueous samples.

A novel and simple approach to sorptive materials for the extraction of organic compounds from environmental samples is presented. It entails the use of glass fiber fabric strips coated with a customized poly(acrylate) (PA) formulation as extraction medium. Analytes were enriched by means of shaking of the PA strip in the sample and then subsequently thermally desorbed and analyzed by GC-MS. The performance of the sorptive materials was evaluated by the enrichment of compounds with different polarities (phenols, hexachlorobenzene and hexachlorocyclohexanes) from water samples. Parameters that affect the extraction process such as pH, ionic strength of the solvent, mixing mechanism, extraction time and desorption conditions were investigated. The extraction abilities of the PA extraction medium were compared with that of commercially available poly(dimethylsiloxane) (PDMS) Twisters. The results revealed that the new material shows higher affinity for phenolic compounds presumably due to the presence of polar groups. The partition coefficients for the PA strips estimated in this work were up to 15 times higher than for the PDMS Twister, resulting in higher recoveries and lower detection limits. The method was applied for the quantification of the aforementioned compounds in contaminated surface water samples from Bitterfeld (Germany). Using both PA strips and PDMS Twisters, good agreement of the extraction data was achieved.

Dimethylpolysiloxanes↗