Unveiling the electronic transformations in the semi-metallic correlated-electron transitional oxide Mo8O23.

Mo8O23 is a low-dimensional chemically robust transition metal oxide coming from a prospective family of functional materials, MoO3-x, ranging from a wide gap insulator (x = 0) to a metal (x = 1). The large number of stoichometric compounds with intermediate x have widely different properties. In Mo8O23, an unusual charge density wave transition has been suggested to occur above room temperature, but its low temperature behaviour is particularly enigmatic. We present a comprehensive experimental study of the electronic structure associated with various ordering phenomena in this compound, complemented by theory. Density-functional theory (DFT) calculations reveal a cross-over from a semi-metal with vanishing band overlap to narrow-gap semiconductor behaviour with decreasing temperature. A buried Dirac crossing at the zone boundary is confirmed by angle-resolved photoemission spectroscopy (ARPES). Tunnelling spectroscopy (STS) reveals a gradual gap opening corresponding to a metal-to-insulator transition at 343 K in resistivity, consistent with CDW formation and DFT results, but with large non-thermal smearing of the spectra implying strong carrier scattering. At low temperatures, the CDW picture is negated by the observation of a metallic Hall contribution, a non-trivial gap structure in STS below ∼170 K and ARPES spectra, that together represent evidence for the onset of the correlated state at 70 K and the rapid increase of gap size below ∼30 K. The intricate interplay between electronic correlations and the presence of multiple narrow bands near the Fermi level set the stage for metastability and suggest suitability for memristor applications.

Crystal structure of indapamide determined from powered diffraction data.

Indapamide is used in the treatment of hypertension. In the European Pharmacopoeia it is specified that indapamide may contain up to 3 wt.% of water. On the basis of the results of thermal (TGA, DSC), DVS and X-ray powder diffraction analyses it has been supposed that this feature arises from the fact that indapamide exists in the form of a non-stoichiometric hydrate. The water molecules are only weakly and reversibly bound into the crystal structure. The major framework of the crystal structure, built of indapamide molecules, remains practically unchanged upon dehydration and/or hydration processes. In order to prove this hypothesis and understand the hydration-dehydration behavior, the as yet unknown crystal structure of indapamide needed to be determined. Since it was not possible to grow any adequate single crystals, we decided to solve the structure from laboratory X-ray powder diffraction data. The solved structure confirmed the hypothesis of weakly bound water in the voids between the indapamide molecules and also served as a basis to evaluate and explain the relative humidity dependence of the unit cell parameters of indapamide.

Characterization of piroxicam crystal modifications.

Piroxicam polymorphism was extensively studied in the past. The objective of the present work was to evaluate polymorphism of piroxicam once again and to characterize the obtained crystal forms. Three polymorphic forms and one monohydrate form were obtained by crystallization from saturated solutions in various solvents. Polarity of solvents and crystallization rate defined by temperature of crystallization were found to be critical parameters in determining the polymorphic form. A new polymorphic form designated as form III was obtained by forced crystallization using dry ice. Only form I with the highest melting point was found to be stable under mechanical and thermal stress. Differences in IR spectra were attributed mainly to the differences in number and positions of H-bonds in the piroxicam crystal forms. Slow crystallization of piroxicam from absolute ethanol solution resulted in a mixture of form II and monohydrate. Crystal structure analysis proved that form II represents form alpha(2) already proposed in the literature. Differences in dissolution rates among crystal forms of piroxicam were attributed to differences in their wettability, where highest wettability was obtained for monohydrate and the lowest for form III.

Síndrome de Ehlers Danlos y embarazo: presentación de un caso y revisión de la literatura / Ehlers Danlos Syndrome and pregnancy: a case report and literature review

El síndrome de Ehlers Danlos es una alteración hereditaria del tejido conectivo, manifestada por una síntesis inadecuada de colágeno. Se caracteriza por un incremento en la elasticidad y fragilidad muscular, tegumentaria, vascular y en ligamentos; su asociación con el embarazo es poco frecuente y la experiencia reportada en cuando a evolución, manejo y complicaciones del mismo es escasa, siendo estas últimas graves para el binomio fetal. Se presenta el caso de un paciente primigesta con embarazo de 39.1 SDG asociado a síndrome de Ehlers Danlos, así como la descripción del control prenatal y resolución del embarazo. Se realiza revisión de la literatura y la relación que existe con respecto a complicaciones y manejo específico