The structures and electrical properties of four NASICON compositions, Na1.4M1.6In0.4(PO4)3 (M = Ti, Sn, Hf, Zr), have been determined and compared. Rietveld refinement of powder X-ray diffraction data confirmed the basic rhombohedral NASICON structure with random occupancy of the octahedral In/M sites, full occupancy of the Na(1) sites and partial occupancy of the Na(2) sites. For three compositions, M = Zr, Sn, and Hf, the 31P MAS NMR peak intensities of the four detected signals, attributed to four different phosphorus environments [P(OM)4 - n (OIn) n (n = 0−3)], were close to the ratios expected for a random distribution of In/M. For M = Ti, some departures from statistical occupancy were apparent. 23Na MAS NMR data gave evidence for two Na+ positions at room temperature for M = Ti, Sn, attributable to occupation of Na(1) and Na(2) sites. For M = Hf, Zr, only a single signal could be resolved at room temperature, which splits into two signals on cooling to − 50 °C, indicating high Na mobility at room temperature. Impedance data obtained on pressed sintered pellets over the range 25−300 °C showed that bulk ionic conductivities increased and activation energies decreased in the sequence Ti, Sn, Hf, Zr. The geometry of the M1M2 bottleneck has been determined from structural data, and a direct correlation found between activation energy for ion conduction and the bottleneck size.

Electrical conductivity and NMR relaxation times (T 1 and T 2 ) have been determined in the Li 0.18 La 0.61 TiO 3 perovskite. At room temperature, the unit cell constants are a ) 3.865-(1), b ) 3.876(1), and c ) 7.788(2) Å and the space group Pmmm (orthorhombic). In this doubled perovskite, the Rietveld analysis of the X-ray powder pattern showed that La ions occupy preferentially one type of sites (z/c ) 0), and Li and vacancies accommodate with the remaining La at the second site (z/c ) 0.5). From this fact, Li motion should be favored in the plane ab; however, exchanges of Li between contiguous layers are detected above 200 K by NMR spectroscopy. From T 1 and T 2 NMR data, two main relaxation mechanisms have been detected, which have been ascribed to localized exchanges (200-273 K) and extended motions of Li (above 273 K). The dc conductivity shows a non-Arrhenius temperature dependence, and local activation energies of 0.41 and 0.26 eV were obtained in the low-and high-temperature ranges, respectively. Both NMR and electrical conductivity relaxations are described by "stretched exponential" functions, characteristic of correlated ion motions.

Abstract-We have investigated the effect of most common oils used in human nutrition on the development of atherosclerosis in apoE-knockout mice. Seven groups of animals, separated according to sex, were fed for 10 weeks either chow diet or the chow diet 10% (wt/wt) enriched with different oils (palm, coconut, 2 types of olive oil, and 2 types of sunflower oil) without addition of cholesterol. At the end of this period, plasma lipid parameters were measured and vascular lesions scored. None of the diets induced changes in plasma cholesterol concentrations, whereas plasma triglycerides were uniformly reduced in all diet groups. Some diets caused significant reductions in the size of atherosclerotic lesions in males and others in females; males responded most to sunflower oils and females to palm oil and one olive oil (II). The lesion reduction in males consuming sunflower oils was associated with the decrease of triglycerides in triglyceride-rich lipoproteins, whereas the decrease in females consuming olive oil II or palm oil was accompanied by an increase in plasma apoA-I. The increase in plasma apoA-I in the latter condition, is mainly due to overexpression of hepatic message elicited by a mechanism independent of apoE ligand. The data suggest that the different diets modulate lesion development in a gender specific manner and by different mechanisms and that the development of atherosclerosis, due to genetic deficiencies, may be modulated by nutritional maneuvers that may be implemented in human nutrition.

Lithium ionic conductivity of Li 0.5 La 0.5 TiO 3 has been studied using nuclear magnetic resonance ͑NMR͒ and admittance spectroscopy ͑AS͒ techniques. Spin-lattice relaxation and electrical conductivity relaxation are well described in terms of stretched-exponential correlation functions in the time domain of the form (t)ϭexp"Ϫ(t/) ␤ …, but showing different relaxation times scales ( 0 ϭ1.4ϫ10 Ϫ11 s from NMR and 0 ϭ10 Ϫ14 s from AS͒, and activation energies ͑0.15 and 0.4 eV, respectively͒. Different ␤ exponents, 1 from spin lattice relaxation and 0.4 from electric-field relaxation have been also deduced. A microscopic activation energy for lithium motion of 0.15 eV is deduced from both techniques. Discrepancies between both techniques are analyzed and discussed in terms of frequency-dependent correlation effects. ͓S0163-1829͑96͒00225-1͔