Results 261 to 270 of about 340,629 (297)

A resistive Q-switch for low-field NMR systems

Journal of Magnetic Resonance, 2018
An NMR Q-switch was designed and constructed specifically for use with low-field NMR apparatus. This featured a comparatively simple resistive damping design. It served to reduce the r.f. probe ring-down time, and hence reduced the signal acquisition delay from 25 ms to 9 ms, on an Earth's magnetic field NMR system.
J Z, Zhen, K T, O'Neill, E O, Fridjonsson, P L, Stanwix, M L, Johns   +4 more
openaire   +2 more sources

Differentiation of fentanyl analogues by low-field NMR spectroscopy

Analytica Chimica Acta, 2019
Forensic laboratories commonly receive new psychoactive substances such as fentanyl analogues and other synthetic opioids that are difficult to identify. Slight changes to chemical structures, e.g. shifting the position of functional groups such as methyl groups or halogens on the aromatic ring, may not be distinguished using traditional methods.
Jonathan Duffy, Aaron Urbas, Matthias Niemitz, Katrice Lippa, Ioan Marginean   +4 more
openaire   +2 more sources

Optical Atomic Magnetometry for Ultra-Low-Field NMR Detection

2013
Abstract This chapter deals with detection of nuclear magnetic resonance (NMR) signals in the ultra-low-field (ULF) regime, by means of optical atomic magnetometers (OAMs). A general introduction is provided about specific NMR features occurring when nuclei precess in microtesla fields, or weaker.
BEVILACQUA, GIUSEPPE, BIANCALANA, VALERIO, DANCHEVA, YORDANKA, MOI, LUIGI   +3 more
openaire   +3 more sources

NMR Spectroscopy for Chemical Analysis at Low Magnetic Fields

2011
This chapter addresses the limits of low-field NMR spectroscopy for chemical analysis and will answer the question of whether high-resolution NMR spectroscopy for chemical analysis of solutions can be achieved with magnetic fields much lower than 0.1 T without losing the chemical information which at high field is derived from the chemical shift and ...
Glöggler, S., Blümich, B., Appelt, S.
openaire   +3 more sources

Low-Field NMR Line Shape Dueto Anisotropic Local Fields. II

Journal of the Physical Society of Japan, 1993
The effects of the random modulation of fluctuating local fields on the NMR spectrum in a weak external dc-field are studied using a numerical method. The local field is assumed to change through the three-dimensional anisotropic Gaussian-Markovian processes.
Yoshio Aoyama, Motoyuki Tanaka
openaire   +1 more source

Hyphenated low‐field NMR techniques: combining NMR with NIR, GPC/SEC and rheometry

Magnetic Resonance in Chemistry, 2015
Hyphenated low‐field NMR techniques are promising characterization methods for online process analytics and comprehensive offline studies of soft materials. By combining different analytical methods with low‐field NMR, information on chemical and physical properties can be correlated with molecular dynamics and complementary chemical information.
Räntzsch, Volker, Wilhelm, Manfred, Guthausen, Gisela   +2 more
openaire   +3 more sources

A low-field, low-cost Halbach magnet array for open-access NMR

Journal of Magnetic Resonance, 2005
A working prototype of a novel low-cost Halbach-array-based NMR system is described. The new design provides open access to the sample relative to conventional NMR magnet designs and this facilitates the simultaneous use of multi-sensor techniques on the same sample, in which NMR/MRI can potentially be combined with other spectroscopies such as ...
B P, Hills, K M, Wright, D G, Gillies
openaire   +2 more sources

Strong pulsed excitations using circularly polarized fields for ultra-low field NMR

Journal of Magnetic Resonance, 2014
A pulse, which is produced by a single coil and thereby has a linear polarization, cannot coherently drive nuclear spins if the pulse is stronger than the static field B0. The inaccuracy of the pulse, which arises from the failure of the rotating wave approximation, has been an obstacle in adopting multiple pulse techniques in ultra-low field NMR where
Jeong Hyun, Shim, Seong-Joo, Lee, Kwon-Kyu, Yu, Seong-Min, Hwang, Kiwoong, Kim   +4 more
openaire   +2 more sources

Oil-Viscosity Predictions From Low-Field NMR Measurements

SPE Reservoir Evaluation & Engineering, 2005
Summary Canada contains vast reserves of heavy oil and bitumen. Viscosity determination is key to the successful recovery of this oil, and low-field nuclear magnetic resonance (NMR) shows great potential as a tool for estimating this property. An NMR viscosity correlation previously had been developed that is valid for order-of-magnitude
J. Bryan, A. Kantzas, C. Bellehumeur
openaire   +1 more source

Low-field NMR

Journal of Magnetic Resonance (1969), 1986
Deborah J Kerwood, Philip H Bolton
openaire   +1 more source