The potential of 17O NMR spectroscopy for the investigation of A2B2O7 ceramic oxides important in the encapsulation of radioactive waste is demonstrated, with post-synthetic enrichment by exchange with 17O2 gas. For Y2Sn2O7, Y2Ti2O7 and La2Sn2O7 pyrochlores, enrichment of the two distinct O species is clearly non quantitative at lower temperatures (∼700 °C and below) and at shorter times, despi...

-35Cl NQR and calorimetric measurements in BCPS have been reinvestigated between 77 K and room temperature (NQR) and between 100 K and 180 K (C~). It is shown that, in contradiction with conclusions found in literature, there is no lock-in transition at 11 5 K. These

Electron paramagnetic resonance spectroscopy at 139.5 GHz has been used to study p21 ras complexed with Mn(II) and guanosine 5'-(beta, gamma-imidotriphosphate), an analog of GTP. The p21 sample studied was selectively labeled with [17O gamma]threonine to a final enrichment of 30%. A Mn(II)-17O hyperfine interaction was observed, but the value of the coupling constant, 0.11 +/- 0.04 mT, is the s...

Pulsed NQR has been used to get information about the two phase transitions (PT) in 4,4'-dichlorobenzophenone. The measurements of the NQR spectrum and spin-lattice relaxation suggest that the PT's correspond to a normal-incommensurate and to the lock-in of a commensurate structure at lower temperature. Strong hysteresis has been observed, which could be assigned to memory effects produced by d...

For the first time, 17O NMR studies were performed on 17O-enriched crystalline pyrophosphates (magnesium-, sodium- and barium-pyrophosphate) by means of triple-quantum magic-angle spinning (3QMAS) and double-rotation (DOR) in the high external field of 17.6 T. Oxygen atoms in bridging positions (P-OB-P) exhibit a significant higher quadrupole coupling constant compared to oxygen atoms in termin...

the analysis of the 27al and 35cl quadrupole coupling parameters of aluminum methyl chloride dimers were carried out on the basis of the density functional theory (dft). the available experimental values of quarupole coupling constants were compared with their calculated ones. in this investigation, the correlations were made between calculated 27al and 35cl nuclear quadrupole coupling constant...

The sodium ion-translocating NADH:quinone oxidoreductase (Na(+)-NQR) from the pathogen Vibrio cholerae exploits the free energy liberated during oxidation of NADH with ubiquinone to pump sodium ions across the cytoplasmic membrane. The Na(+)-NQR consists of four membrane-bound subunits NqrBCDE and the peripheral NqrF and NqrA subunits. NqrA binds ubiquinone-8 as well as quinones with shorter pr...

NaN02 is a famous ferroelectric material with spontaneous polarization (Ps) along the crystallographic b-axis, which undergoes an order-disorder transition at Tc = 437 K [1 3]. The Ps, arising from the ordering of N 0 2 and the accompanying shift of Na, is sensitive to the environment. Information on the local structure in NaN02 has been obtained by employing N NQR [4 5]. A change of the local ...