th  - 1988 - 51st ENC Conference

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PERFORMANCE COMPARISON OF DOUBLE-TUNED SURFACE COILS
J.R. Fitzsimmons*, H.R. Brooker, W. Kuan, and B. Beck
Departments of Radiology and Physics
University of Florida, Sainesville, FL 32611
Recently, several groups have tried to extend the utility of radio frequency (rf)
coils used in NMR spectroscopy and imaging by designing rf coils which resonate at
two or more frequencies (I-3). This study evaluates the advantages and disadvan-
tages of several of the more recent designs suggested by the literature including
one of our own making. In particular, we compare I) the design suggested by
Schnall, et al (I) which makes use of rf "trap" circuits, 2) the loop gap resonator
approach suggested by Grist, et al (2), 3) the transformer coupled planar design by
Fitzsimmons, et al (3). In addition, a set of single tuned coils were constructed
(85 MHz and 34 MHz) to serve as the standard for the above designs. All of these
designs were constructed using the same conductor type (#14 solid copper), capacitor
type (Sprague IOTCC series), diameter coil (4.8cm) and balanced matching scheme.
Two phantoms were used for these experiments, one containing DeO and saline to
approximate the loading effects of the human arm muscle and the other using dilute
phosphoric acid with saline. The unloaded and loaded Q of each coil was measured
using a sweep generator and 50 ohm bridge and each coil was evaluated on a 2.0T SIS
imager/spectrometer using a one pulse experiment. Signal to noise (S/N) measure-
ments were made for each coil at each frequency. Significant differences were found
between coils and within coils on different frequencies.
This research is supported by grants from the National Institute of Health
(P41-RR-02278) and the Veterans Administration Medical Service
I. Schnall, MD, Subramanian, VH, Leigh, JS, and Chance, B. J. Magn. Resort. 65,
122-129 (1985).
2. Grist, T.M., J.B. Kneeland, A. Jesmanowicz, W. Froncisz, and J.S. Hyde.
Fifth Annual Meeting of the Society of Mag. Res. in Med. August, 1986.
~. J.R. Fitzsimmons, H.R. Brooker, B. Beck, Mag. Res. In Med. 5,471-477,1987.
I-- 10g I NMR STUDY OF ALKALINE HYDROLYSIS OF POLY-(ACRYLONITRILE)
(PAN): J. Lovy*, V. Stoy, Kingston Technologies, Inc., Dayton, New
Jersey, 08810.
Although alkaline hydrolysis of PAN has been utilized commercially
as well as studied for many decades, its mechanism was not sufficiently
known.
According to the former studies, the mechanism of hydrolysis of
PAN was essentially identical with hydrolysis of an isolated nitrile
group. The formation of cyclic groups of tetrahydronaphthyridine type
was suggested as a mere minor by-product.
By detailed NMR study we have found that products of alkaline
hydrolysis contain acrylamidine (which was never reported before) in
substantial concentrations. Its formation requires a cyclic mechanism
involving at least two CN groups in 1,3 position.
The further studies of akaline hydrolysis of PAN and a model
compound (glutaronitrile) have shown that the cyclic mechanism is the
dominant one. The influence of reaction conditions and media was also
studied.
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