نتایج جستجو برای: surface nmr signal
تعداد نتایج: 1078099 فیلتر نتایج به سال:
In-situ nuclear magnetic resonance (NMR) core flooding system has enabled researchers to monitor several rock properties such as porosity, pore size distribution, and fluid saturation along the tested samples with high resolutions under reservoir conditions. However, spatially resolved strength/mechanical property alteration coupled migration/substitution remains poorly characterized. To this e...
Scalar coupling constants and signal splitting patterns in NMR spectra contain a wealth of short-range structural information. The extraction of these parameters from (1)H NMR spectra is often prohibited by simultaneous scalar coupling interactions with several other protons. Here we present a high-resolution NMR experiment where scalar coupling to only one selected signal is visible. All other...
in this study, a method for determining the location and extent of myocardial infarction using body surface potential map data that is obtained from physionet challenge 2007 database has been suggested. this data is related to four patients with myocardial infarction that we used from two patients as training set to determine rules, and from two other patients for testing set and the conclusion...
Wettability and NMR surface relaxation are related to each other. Wettability controls the fluid distribution in porous media. NMR surface relaxation dictates that the fluid in contact with the mineral surface has a relaxation time shorter than its bulk value. In this study, first, the nature of wettability effect on NMR responses was demonstrated by a parameter ρ2, eff, the effective surface r...
Two new hexahydropyrimidine compounds were prepared in high yield by condensation of an equimolar amount of 1,3-diamine with 2-dipyridylketone at room temperature in dichloromethane. The desired hexahydropyrimidine structures were confirmed on the basis of their UV-Visible, elemental analysis, FT-IR, 1H-NMR, TG/DTG, and EI-MS ...
After initial proof-of-principle demonstrations, optically pumped nitrogen-vacancy (NV) centres in diamond have been proposed as a non-invasive platform to achieve hyperpolarisation of nuclear spins molecular samples over macroscopic volumes and enhance the sensitivity magnetic resonance (NMR) experiments. In this work, we model process polarisation external by NV theoretically evaluate their p...
T1 NMR Relaxation and Petrophysical Properties Marc Fleury 1 1 IFP Energies Nouvelles NMR relaxation is routinely used in the field of geosciences to give basic petrophysical properties such as porosity, pore size distribution, saturation etc. In this tutorial, we will give the basic principle used in the interpretation of the NMR signal and compare the results with other standard petrophysical...
This paper discusses a new nuclear magnetic resonance (NMR) method that can provide wettability, saturation, and oil viscosity values in rocks partially saturated with oil and brine. The method takes advantage of two new technological advances in NMR well logging—the MRF* Magnetic Resonance Fluid Characterization Method and NMR “diffusion-editing” (DE) pulse sequences. We discuss the principles...
Introduction: Application of biofeedback techniques in rehabilitation has turned into an exciting research area during the recent decade. Providing an appropriate visual or auditory biofeedback signal is the most critical requirement of a biofeedback technique. In this regard, changes in Surface Electromyography (SEMG) signals during wrist movement can be used to generate an indictable visual b...
In situ solid-state NMR methodologies have been used to investigate the photocatalytic oxidation of ethanol (CH3CH2OH) over a series of SnO2-based photocatalysts. The adsorption of ethanol on commercially available SnO2 powder was studied using both cross-polarization 13C NMR and REDOR experiments, and showed the formation of two surface ethanol species, hydrogen-bonded ethanol at surface hydro...
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