No abstract

A detailed structural study of the incorporation of Fe into SrTiO 3 nanoparticles is reported. Slightly irondoped strontium titanate nanoparticles with 0, 1, 3 and 5 mol% concentration of iron were grown using a sol-gel hydrothermal process and characterised using Raman scattering, X-ray photoelectron and X-ray diffraction spectroscopy. The amorphisation of the nanostructures was observed as the iron content increased, which was confirmed by the TEM images. The XPS results indicated that the oxidation states of the Sr atoms were maintained in 2?. However, a mixture of Fe 3? and Fe 4? atoms was observed as the Fe content increased, resulting in a significant number of oxygen vacancies in the perovskite structure. The analysis of Raman spectra indicated that the intensity, linewidth and frequency shift of the TO 4 phonon can be used as an indicator of the Fe content as well as a local temperature probe for future thermal analysis. Graphical abstract Temperature evolution of the Raman spectra of STO:Fe 1 mol%. The peaks with star correspond to the second-order processes. (b) Temperature dependence of the TO 4 phonon mode. Blue dots denote measured Raman spectra, and the red solid lines are the Lorentzian fits to respective spectra.

A new synthetic route to obtain high-purity strontium titanate, SrTiO3, using the sol–gel-hydrothermal reaction of TiCl4 and a SrCl2 solution in an oxygen atmosphere has been developed. In the synthesized products the SrTiO3 nanoparticles are nearly spherical and decrease in size with the reaction time (48 h) down to a diameter of about 40 nm. The microstructure and composition of the as-synthesized samples were investigated by X-ray diffraction (XRD), high-resolution TEM (HRTEM), Raman spectroscopy, atomic force microscopy (AFM), and energy-dispersive X-ray spectroscopy (EDX). All the samples were identified as cubic perovskite phase.This work has been partially financed by FONDECYT Grant under contract No 1080401. The authors thank the Facultad de Ciencias Fı´sicas y Matema´ticas of the Universidad de Chile for the use of their analytical equipment (XRD, TEM, and XPS). R.A.Z. acknowledges FUNDACION ANDES Grant under contract No C-13876

Código numérico 2001-2420Palabras clave Cuero cabelludo. Colgajos. Código numérico 2001-2420Presentamos una serie de casos realizados en el Servicio de Cirugía del Hospital Clínico San Pablo en Coquimbo, Chile, entre Abril de 1998 y Abril de2005. Se trata de un grupo de estudio de 22 pacientes consecutivos con pérdida traumática o quirúrgica del cuero cabelludo, mayor de 3cm de diámetro. Se empleó para la reconstrucción colgajo semilunar, en espejo o en remolino vascularizados a partir de las ramas principales del cuero cabelludo. Analizamos en cada caso el tamaño del defecto, pérdida de hueso asociada, tipo de cirugía, resultados de la cobertura y complicaciones.La edad media de los pacientes fue de 40.6 años con un rango entre 3 y 71 años. El área anatómica comprometida fue parietal en 11 pacientes (50%), temporal en 7 (31,8%), occipital en 3 (13,6%) y frontal en 1 caso (4,5%). La causa de la pérdida de sustancia fue resección de tumores malignos o benignos en 10 casos, postraumática en 5, postquirúrgica en 4, y por alopecia en 3. El tamaño medio del defecto fue de 147 cm 2 con un rango entre 28 y 615 cm 2 .El colgajo empleado fue doble en espejo en 10 casos (50%), semilunar de deslizamiento en 9 (36,4%) y en remolino en 3 (13,6%). En 6 pacientes se utilizó un injerto dermo-epidérmico para cerrar un defecto residual del área dadora del colgajo (dos semilunares y dos en espejo). Veintiun pacientes (45%) evolucionaron sin incidencias, con cicatrización del colgajo en un plazo máximo de 21 días. Un paciente con pérdida ósea tras dos craneotomías, presentó necrosis parcial distal del colgajo y falleció por neumonía aspirativa.Comparamos los tres tipos de reparación de acuerdo al tamaño del defecto y a la superficie del mismo. La elección de colgajo doble en espejo, remolino o semilunar, al aplicar la prueba de Kruskal Wallis, no se relacionó con la superficie del defecto, y la elección del colgajo fue atribuible al azar, p > 0.05. La principal razón para escoger uno u otro fue la ubicación del defecto.En conclusión, la estrategia de reconstrucción del cuero cabelludo mediante colgajos arterializados permite el cierre de grandes defectos en una operación fácil y con cicatrices inaparentes que quedan ocultas bajo el cabello. Es por ello que creemos que estos procedimientos son la mejor alternativa de tratamiento y recomendamos su uso por sus resultados fiables cuando se siguen los principios técnicos del manejo de colgajos. We present sucessive cases performed at Surgery Department of Hospital San Pablo, Coquimbo, Chile, between April1998, and April 2005: Twenty two consecutive patients suffering surgical or postinjury scalp defects, greater than 3 cm of diameter. Semilunar flap, mirror flap, or multiple pinwheel flap arterialized from the main scalp arteries were used for reconstruction. We determinate in every case the large of the defect, asociated bone loss, kind of surgery, end result and complications. Reconstrucción inmediata de cuero cabelludoPatients' mean age was 40.6 years with rank between 3 and 71 years...

CuO nanowires were successfully made through a simple wet chemical method at room temperature by immersing on copper sheets in a 4 M ammonia solution for 4 days and then subjecting it to heat treatment. Immersion time and heat treatment have an important effect on the length, diameter, and density of the CuO nanostructures. X-ray powder diffraction (XRD) patterns indicated that the samples are composed of a single phase, CuO. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy studies showed that the wet-treated samples consisted of nanofiber-like structures of monoclinic CuO, while the heat-treated samples consisted of well-defined nanowires which also exhibited the monoclinic phase.

No abstract

Barium titanate (BaTiO 3 ) powders with particle sizes about 50 nm in diameter were synthesized using a hydrothermal route. The powders were characterized using various experimental techniques such as XRD, TEM and Raman spectroscopy, and they showed a good crystallinity and homogeneity without heat treatments. Also, Raman spectra showed the presence of the tetragonal phase. In addition, various calcination treatments were made to BaTiO 3 powders with the purpose to improve their ferroelectric properties. In general, calcination treatments improved the crystallinity and homogeneity of the samples considerably but did not modify the internal structure of the BaTiO 3 , which was observed in the Raman spectra. On the other hand, from theoretical calculations were established that the cubic phase should be better dielectric in comparison with the tetragonal phase, but this latter would have better optical properties. However, experimental evidences are indicative that the cubic phase would predominate in the synthesis of the compound.

Chavez-Angel E.. Synthesis and optical characterization of Er-doped bismuth titanate nanoparticles grown by sol-gel hydrothermal method. Ceramics International, (2017). 43.