Displasia tanatofórica de grado II: reporte de un caso y revisión de la literatura

La displasia tanatofórica (DT) es la osteocondrodisplasia más letal que existe en el periodo neonatal. Se caracteriza por miembros cortos, macrocefalia, tronco de longitud normal y tórax estrecho con hipoplasia pulmonar. Se clasifica en dos subtipos clínicamente definidos: la DT tipo I (DTI), es el subtipo más común y se caracteriza por presentar huesos largos curvados (fémur en forma de receptor telefónico) con o sin deformaciones craneales, y la DT tipo II (DTII), en que los fetos presentan cráneos en forma de “hoja de trébol” y fémures rectos. Muchas de las alteraciones morfológicas de este tipo de enanismo coinciden en ambos subtipos: micrognatia o platispondilia vertebral. Actualmente existen varias formas de diagnosticar este trastorno por imágenes clínicas o técnicas moleculares. Se presentan los hallazgos clínicos y de imagen de un feto de 36 semanas de gestación que presentó macrocefalia, frente prominente, puente nasal plano, costillas cortas y gruesas, tórax estrecho, micromelia extrema y vértebras planas, asociados a una rotura prematura de membrana, en que se estableció el diagnóstico de DT tipo II

Comparative study on the properties of ZnO nanowires and nanocrystalline thin films

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The microstructural, morphological, optical and water-adsorption properties of nanocrystalline ZnO thin films and ZnO nanowires were studied and compared. The ZnO thin films were obtained by a sol-gel process, while the ZnO nanowires were electrochemically grown onto a ZnO sol-gel spin-coated seed layer. Thin films and nanowire samples were deposited onto crystalline quartz substrates covered by an Au electrode, able to be used in a quartz crystal microbalance. X-ray diffraction measurements reveal in both cases a typical diffraction pattern of ZnO wurtzite structure. Scanning electron microscopic images of nanowire samples show the presence of nanowires with hexagonal sections, with diameters ranging from 30 to 90 nm. Optical characterization reveals a bandgap energy of 3.29 eV for the nanowires and 3.35 eV for the thin films. A quartz crystal microbalance placed in a vacuum chamber was used to quantify the amount and kinetics of water adsorption onto the samples. Nanowire samples, which have higher surface areas than the thin films, adsorb significantly more water. (C) 2012 Elsevier B.V. All rights reserved.2135964Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CLAFSwedish Government Strategic Research Area Grant in Materials ScienceCITEDEFCONICETPEDECIBA-FisicaANII (Agencia Nacional de Investigacion e Innovacion)Universidad de la Republica, in Montevideo, UruguayConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [490580/2008-4

Structural characterization of supported nanocrystalline ZnO thin films prepared by dip-coating

Nanocrystalline ZnO thin films prepared by the sol-gel dip-coating technique were characterized by grazing incidence X-ray diffraction (GIXD), atomic force microscopy (AFM), X-ray reflectivity (XR) and grazing incidence small-angle X-ray scattering (GISAXS). The structures of several thin films subjected to (i) isochronous annealing at 350, 450 and 550 degrees C, and (ii) isothermal annealing at 450 degrees C during different time periods, were characterized. The studied thin films are composed of ZnO nanocrystals as revealed by analysing several GIXD patterns, from which their average sizes were determined. Thin film thickness and roughness were determined from quantitative analyses of AFM images and XR patterns. The analysis of XR patterns also yielded the average density of the studied films. Our GISAXS study indicates that the studied ZnO thin films contain nanopores with an ellipsoidal shape, and flattened along the direction normal to the substrate surface. The thin film annealed at the highest temperature, T = 550 degrees C, exhibits higher density and lower thickness and nanoporosity volume fraction, than those annealed at 350 and 450 degrees C. These results indicate that thermal annealing at the highest temperature (550 degrees C) induces a noticeable compaction effect on the structure of the studied thin films. (C) 2011 Elsevier B.V. All rights reserved.Brazilian Synchrotron Light Laboratory (LNLS)LNLSFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESPSECyTCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES/SECyTCNPq/CONICETConsejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq (PROSUL)ANPCyTAgencia Nacional de Promoción Científica y Tecnológica (ANPCyT)CONICETConsejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET)YPF FoundationYPF Foundatio

Comparative study on the properties of ZnO nanowires and nanocrystalline thin films

The microstructural, morphological, optical and water-adsorption properties of nanocrystalline ZnO thin films and ZnO nanowires were studied and compared. The ZnO thin films were obtained by a sol–gel process, while the ZnO nanowires were electrochemically grown onto a ZnO sol–gel spin-coated seed layer. Thin films and nanowire samples were deposited onto crystalline quartz substrates covered by an Au electrode, able to be used in a quartz crystal microbalance. X-ray diffraction measurements reveal in both cases a typical diffraction pattern of ZnO wurtzite structure. Scanning electron microscopic images of nanowire samples show the presence of nanowires with hexagonal sections, with diameters ranging from 30 to 90 nm. Optical characterization reveals a bandgap energy of 3.29 eV for the nanowires and 3.35 eV for the thin films. A quartz crystal microbalance placed in a vacuum chamber was used to quantify the amount and kinetics of water adsorption onto the samples. Nanowire samples, which have higher surface areas than the thin films, adsorb significantly more water