The anomalous temperature dependence of NQR frequencies which is often observed in crystals in which there is reorientational motion of ions or molecules is considered. Two theories of the phenomena, the jump rotation theory and the pseudo-spin theory, are described, and their successes and failures are discussed. The importance of considering other properties such as pressure dependence of NQR...

There are two principal mechanisms of acetylcholine (ACh) release from the resting motor nerve terminal: quantal and non-quantal (NQR); the former being only a small fraction of the total, at least at rest. In the present article we summarize basic research about the NQR that is undoubtedly an important trophic factor during endplate development and in adult neuromuscular contacts. NQR helps to...

A reinvestigation of the nitrogen-14 NQR in thiourea has permitted to record, apparently for the first time, the resonances above 169 K. The first order and second order of the transitions at 169 K and 202 K, respectively, appear clearly from the temperature dependence of the resonance frequencies; the modulated structure, incommensurate or commensurate, is also seen on the N NQR spectrum. This...

Z. Naturforsch. 51a, 793 -796 (1996); received February 1, 1996 We have carried out Ru N M R and NQR measurements in superconductor CeRu 2 having Tc = 6.1 K in the temperature range of 1 . 3 3 0 K. From the 9 y Ru N M R in 10.2 T above H c 2 , T { T c o n s t was found in the measured-T range, and the value of T , T K 2 is almost the same as that in the uncorrelated Korringa relation, suggestin...

The performance of rectangular radio frequency (RF) coils capable of being used to detect nuclear quadrupole resonance (NQR) signals from blister packs of medicines has been compared. The performance of a fixed-pitch RF coil was compared with that from two variable-pitch coils, one based on a design in the literature and the other optimized to obtain the most homogeneous RF field over the whole...

A pulsed NQR spectrometer specifically designed to facilitate real-time tuning of pulse sequence parameters is described. A modular approach based on the interconnection of several rack-mounted blocks provides easy access to all spectrometer signals and simplifies the task of modifying the spectrometer design. We also present experimental data that demonstrates the ability of the spectrometer t...

The 1 2 7 I-NQR of(HOCH 2 )3 CNH 3 I was determined in the range 77 < T/K<310. At T = 310 K the NQR signal fades out (Tm = 463 K). The 127I spectrum ( T =77 K.): v, =29.195 MHz, v2 = 14.597 MHz, rj(121l)=0, e Q # zz6 _ 1 (1 2 7 I) = 97.315 MHz, is in agreement with the crystal structure. The 127I NQR spectrum of l,3-diammonium-2,2-dimethylpropane diiodide, (H 3 NCH 2 C(CH 3 ) 2 CH 2 N H 3)2+ -2...

A very high sensitivity continuous wave NQR spectrometer was developed to detect pure NQR transitions at low frequencies (down to 200 kHz). A signal-to-noise ratio of more than 100 to 1 has been achieved at about 1.36 MHz for crystalline B 2 0 3 . Two large n B responses have been found in vitreous B 2 0 3 (NMR detected only one site) with linewidths of less than 30 kHz. A1 NQR spectra were obt...

The objectives were to estimate aluminum (Al) oral bioavailability under conditions that model its consumption in drinking water, and to test the hypotheses that stomach contents and co-administration of the major components of hard water affect Al absorption. Rats received intragastric 26Al in the absence and presence of food in the stomach and with or without concomitant calcium (Ca) and magn...

The results of comparison of experimental C1 NQR parameters for a great number of organic and organometallic compounds and estimated ones using ab initio calculations at the RHF/6-31G(d) level were systematized. The NQR frequency changes on going from one compound to another depend, in general, on the changes of populations of the CI atom p„-orbitals in these compounds and, first of all, of pop...