Selective drug trace detection with low-field NMR

Characterization of Shales with Low Field Nmr

Nuclear Magnetic Resonance (NMR) relaxation methods are key techniques for evaluating shales, both from cores and logging data. First, very small pore sizes, down to nano-meter length scales, can be detected and quantified if the NMR tool has the ability to measure relaxation times in the range [0.1 – 1 ms], and second the different proton populations (water, oil, gas, organic matter) can be di...

Low-field NMR measurement procedure when SQUID detection is used.

In reported low-field nuclear magnetic resonance (NMR) measurements using Superconducting Quantum Interference Device (SQUID) detection, the pre-polarizing magnetic field has been usually oriented orthogonal to the measuring field, B(p) perpendicular B(m). Melton et al. systematically analyzed the consequences of B(p) decay in time after turnoff and showed that this decay should be nonadiabatic...

Zero field NMR and NQR with selective pulses and indirect detection

Zero field NMR and NQR spectra are obtained by the application of dc magnetic field pulses to a demagnetized sample. Pulsed dc fields allow for selective excitation of isotopic species and provide a means for coherent manipulation of the spin system in zero field. Using these selective pulses and level crossing techniques, indirect detection of a quadrupolar nucleus may be accomplished via prot...

Permanent Magnet Arrangements for Low-Field NMR

For low-field NMR, NdFeB permanent magnet arrangements are proposed to provide the static polarizing magnetic field. Especially a parallel and a circular arrangement of the permanent magnets, iron yokes and small shim magnets were tested and improved by COMSOL. The intent was to guide the design and the construction of NMR magnets by calculating the magnetic field strength and the associated fi...

اندازه گیری پراکندگی تخلخل در مخازن کربناته با استفاده از(Low Field NMR)