Single crystals of L-valine, C 5 H 11 O 2 N, have been studied by Raman spectroscopy at temperatures from 17 to 300 K over the spectral range 20-3300 cm −1 . A tentative assignment of the bands is given. Careful analysis of the Raman spectra suggests that a series of changes in the low-wavenumber region may be associated with a phase transition undergone by the material, and this possibility is discussed.

Overwhelming evidence supports the importance of the sympathetic nervous system in heart failure. In contrast, much less is known about the role of failing cholinergic neurotransmission in cardiac disease. By using a unique genetically modified mouse line with reduced expression of the vesicular acetylcholine transporter (VAChT) and consequently decreased release of acetylcholine, we investigated the consequences of altered cholinergic tone for cardiac function. M-mode echocardiography, hemodynamic experiments, analysis of isolated perfused hearts, and measurements of cardiomyocyte contraction indicated that VAChT mutant mice have decreased left ventricle function associated with altered calcium handling. Gene expression was analyzed by quantitative reverse transcriptase PCR and Western blotting, and the results indicated that VAChT mutant mice have profound cardiac remodeling and reactivation of the fetal gene program. This phenotype was attributable to reduced cholinergic tone, since administration of the cholinesterase inhibitor pyridostigmine for 2 weeks reversed the cardiac phenotype in mutant mice. Our findings provide direct evidence that decreased cholinergic neurotransmission and underlying autonomic imbalance cause plastic alterations that contribute to heart dysfunction.

Raman spectra of sintered NaNbO 3 ceramics prepared by a new chemical route were obtained for temperatures between 15 and 297 K. From analysis of the results and dielectric permittivity measurements, we observed that the ceramic undergoes two diffuse phase transitions. The first phase transition was observed between 240 and 300 K and the second between 40 and 70 K. Also, analysis of band linewidths points to an orientational mechanism dominating the peak damping and a weak contribution of the anharmonic effect, in contrast to previous results obtained at high temperature.

Single crystals of L-isoleucine, C 6 H 13 O 2 N, have been studied by Raman spectroscopy at temperatures from 17 to 290 K over the spectral range 20-3300 cm −1 . No evidence of a structural phase transition in this temperature range is found, although some splitting of bands associated with the internal modes has been observed. A tentative assignment of the modes is also given.

Polarized Raman spectra of L-arginine hydrochloride monohydrate single crystal were studied at temperatures ranging from 295 to 10 K. The behavior of the linewidth, wavenumber and intensity of several bands is discussed and related to some particular vibrational modes associated with hydrogen bonds or even to other vibrations, such as CN, CCC, CCN and CH vibrations. The disappearance of some bands in the lattice vibrational region was associated with a phase transition undergone by the crystal between 100 and 110 K.