Inside-out NMR with two concentric ring magnets.

We report the design and the implementation of an inside-out NMR sensor that produces a large sensitive region with substantially uniform magnetic field at a remote location. The construction using a pair of ring magnets is simple yet provides multiple benefits, including large sample volume, operation with low RF power, and the ability to measure samples with long T and high diffusivity. A palm-size inside-out NMR sensor (57 mm OD × 29 mm height, 420 g including the housing and the coil PCB) was built with inexpensive magnets.

Low fields but high impact: Ex-situ NMR and MRI.

"There's plenty of room at the bottom". This was the title of Richard Feynman's well-known lecture in 1959, often considered a seminal event in the history of nano-sciences and technologies. For magnetic resonance (MR), we borrow the statement to suggest a plethora of opportunities in low-field NMR/MRI with miniaturized apparatus, particularly the ex-situ type.

Unilateral NMR with a barrel magnet.

Unilateral NMR can examine samples without regard to sample size. It is also an easy path to mobile or portable NMR as well as inexpensive NMR. The objective of this work was to develop unilateral NMR with an improved performance in a sample region that was remote from the apparatus.

Effect of off-resonance on T saturation recovery measurement in inhomogeneous fields.

Saturation-recovery measurements with Carr-Purcell-Meiboom-Gill sequences are commonly employed to measure the longitudinal relaxation time constant, T, in grossly inhomogeneous fields. We show that in general the off-resonant effect generates unexpected extra signals in the T measurement. In the present study, we derive a modified T kernel that accounts for this off-resonance effect quantitatively.

Transformer-coupled NMR probe.

In this study, we propose an NMR probe circuit that uses a transformer with a ferromagnetic core for impedance matching. The ferromagnetic core provides a strong but confined coupling that result in efficient energy transfer between the sample coil and NMR spectrometer, while not disturbing the B(1) field generated by the sample coil. We built a transformer-coupled NMR probe and found that it offers comparable performance (loss <1 dB) to a conventional capacitor-coupled circuit.

Non-destructive Analysis of Oil-Contaminated Soil Core Samples by X-ray Computed Tomography and Low-Field Nuclear Magnetic Resonance Relaxometry: a Case Study.

Non-destructive measurements of contaminated soil core samples are desirable prior to destructive measurements because they allow obtaining gross information from the core samples without touching harmful chemical species. Medical X-ray computed tomography (CT) and time-domain low-field nuclear magnetic resonance (NMR) relaxometry were applied to non-destructive measurements of sandy soil core samples from a real site contaminated with heavy oil. The medical CT visualized the spatial distribution of the bulk density averaged over the voxel of 0.

Use of magnetic resonance microscopy for the nondestructive observation of xylem cavitation caused by pine wilt disease.

ABSTRACT The development of xylem cavitation caused by pine wilt disease was visualized nondestructively with a compact magnetic resonance (MR) microscope system. A T(1)-weighted spin-echo sequence clearly visualized the water-filled xylem of Japanese black pine (Pinus thunbergii) as white zones, whereas cavitated xylem was represented as dark areas. Cavitated areas in the xylem were first observed 6 to 9 days after inoculation with the pinewood nematode (Bursaphelenchus xylophilus), and enlarged gradually over several days.

Correlation between acoustic emission, water status and xylem embolism in pine wilt disease.

The occurrence of cavitation events and embolism during the latent, early stage and the late developmental stages of pine wilt disease was monitored nondestructively by acoustic emission (AE) and high-resolution magnetic resonance microscopy, respectively, and the results were compared with changes in leaf water potential and stem thickness. In the latent stage of the disease, when no embolisms were observed, cavitation events were detected by AE during the daytime in water-stressed Japanese black pine (Pinus thunbergii Parl.) seedlings, indicating that cavitation occurred at the individual tracheid level.

Thawing of frozen vegetables observed by a small dedicated MRI for food research.

The thawing process for boiled and frozen edible vegetables was traced by a dedicated MRI for food research. The MRI system is small, with a 1.0-T static magnetic field, and can be placed in an ordinary research room with a light air conditioner.

Development of a compact mouse MRI using a yokeless permanent magnet.

A compact mouse MRI has been developed using a 1.0T yokeless permanent magnet and portable MRI console. The entire system was installed in a space measuring 2 m x 1 m.

Development of a compact MRI system for trabecular bone volume fraction measurements.

A compact MRI system for measuring trabecular bone volume fraction (TBVF) of the calcaneus was developed with the use of a 0.21 T permanent magnet and portable MRI console. The entire system weighed < 600 kg and was installed in a 2 m x 2 m space.

Super-parallel MR microscope.

A super-parallel MR microscope in which multiple (up to 100) samples can be imaged simultaneously at high spatial resolution is described. The system consists of a multichannel transmitter-receiver system and a gradient probe array housed in a large-bore magnet. An eight-channel MR microscope was constructed for verification of the system concept, and a four-channel MR microscope was constructed for a practical application.