Formation and decomposition of Lanthanum Monoxocarbonate

Amorphous lanthanum carbonate was prepared by hydrolysis of lanthanum isopropoxide using ammonia water in the atmosphere. Lanthanum monoxocarbonate, La₂O(CO₃)₂ · H₂O, crystallizes when this amorphous material was washed with hot water. The crystallization and thermal behavior of the crystalline material are studied by X-ray diffraction, thermal analysis, and infrared spectroscopy. The decomposition of La₂O(CO₃)₂ · H₂O into type-IA (LaO)₂CO₃ is observed at 440 to 540°C. Decomposition isotherms are described by the contracting cube equation, the activation energy being 42.6 kcal mol^?1. Type-IA (LaO)₂CO₃ subsequently decomposes to A-type La₂O₃ at 750 to 870°C. The kinetics is also interpreted in terms of the contracting cube equation, the activation energy being 58.3 kcal mol^?1.     

Limited slowdown of endocrine-disruptor diffusion in confined fluid lipid membranes

Self-diffusion rates of lipids and trapped bisphenol A (BPA) are determined in various sizes of confined but fluid membranes by high-field-gradient NMR at 600 MHz. Micelles and vesicles of 3- to 400-nm diameters are used as model membranes to get an insight into the molecular diffusion in such soft environments. The slowdown of BPA and lipid motions is leveled off in 100- and 400-nm vesicles, although the hydrodynamic continuum model gives the aggregate motion slowed inversely to the aggregate size. Instead, the limited motion is related to the intra-membrane fluidity.     

Anisotropy of the Raman spectra of nanographite ribbons

A polarized Raman study of nanographite ribbons on a highly oriented pyrolytic graphite substrate is reported. The Raman peak of the nanographite ribbons exhibits an intensity dependence on the light polarization direction relative to the nanographite ribbon axis. This result is due to the quantum confinement of the electrons in the 1D band structure of the nanographite ribbons, combined with the anisotropy of the light absorption in 2D graphite, in agreement with theoretical predictions.