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Search Results: 1 - 10 of 471051 matches for " A. Torres-Pardo "
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Epitaxial Piezoelectric Pb( ) Thin Films on Silicon for Energy Harvesting Devices
A. Sambri,D. Isarakorn,A. Torres-Pardo,S. Gariglio,Pattanaphong Janphuang,D. Briand,O. Stéphan,J. W. Reiner,J.-M. Triscone,Nico F. de Rooij,C. H. Ahn
Smart Materials Research , 2012, DOI: 10.1155/2012/426048
Abstract: We report on the properties of ferroelectric Pb(Zr0.2Ti0.8)O3 (PZT) thin films grown epitaxially on (001) silicon and on the performance of such heterostructures for microfabricated piezoelectric energy harvesters. In the first part of the paper, we investigate the epitaxial stacks through transmission electron microscopy and piezoelectric force microscopy studies to characterize in detail their crystalline structure. In the second part of the paper, we present the electrical characteristics of piezoelectric cantilevers based on these epitaxial PZT films. The performance of such cantilevers as vibration energy transducers is compared with other piezoelectric harvesters and indicates the potential of the epitaxial approach in the field of energy harvesting devices. 1. Introduction In the last decade, studies on epitaxial ferroelectric thin films have led to many interesting results and exciting discoveries [1]. The possibility of tailoring or even enhancing some physical parameters via epitaxial strain engineering [2–4] has suggested the idea of the exploitation of such thin films for several technological applications [5]. Nevertheless, the benefits of the epitaxial approach on the performances of ferroelectric thin film-based devices have to compensate the hurdles related to the epitaxial growth on industrial substrates such as silicon, the modern technological platform. It is in fact well known that the basic requirements for the epitaxy, that is, a good lattice match between substrate and film and a reciprocal chemical stability, are not easily fulfilled in the case of oxide growth on silicon. Beside the difference in lattice parameters and thermal expansion coefficients, the main problem is the surface reactivity of silicon to oxygen, with the formation of an amorphous layer of silicon dioxide that hints any further epitaxy. Moreover, the cations of most ferroelectric compounds interdiffuse into the silicon substrate, forming spurious extra phases at the interface [6]. In order to overcome such difficulties, a suitable buffer layer is needed that acts as a barrier for cations migration and as a structural template for the growth of the ferroelectric epitaxial film [7–9]. PZT is one of the most investigated ferroelectric materials, due to its high values of remnant polarization and piezoelectric coefficients. In the bulk form, it displays a complex phase diagram versus the Ti/Zr content: for the stoichiometry of our choice, that is, Pb( )O3 (PZT 20/80), it is ferroelectric with a tetragonal structure up to a transition temperature of 460°C [10]. It
Spectroscopic mapping of local structural distortions in ferroelectric PbTiO3/SrTiO3 superlattices at the unit-cell scale
Almudena Torres-Pardo,Alexandre Gloter,Pavlo Zubko,Noemie Jecklin,Celine Lichtensteiger,Christian Colliex,Jean-Marc Triscone,Odile Stephan
Physics , 2011, DOI: 10.1103/PhysRevB.84.220102
Abstract: The local structural distortions in polydomain ferroelectric PbTiO3/SrTiO3 superlattices are investigated by means of high spatial and energy resolution electron energy loss spectroscopy combined with high angle annular dark field imaging. Local structural variations across the interfaces have been identified with unit cell resolution through the analysis of the energy loss near edge structure of the Ti-L2,3 and O-K edges. Ab-initio and multiplet calculations of the Ti-L2,3 edges provide unambiguous evidence for an inhomogeneous polarization profile associated with the observed structural distortions across the superlattice.
Método analítico por cromatografía líquida de alta resolución para el estudio de estabilidad del jarabe de loratadina 0,1 %
Torres Amaro,Leonid; García Pe?a,Caridad M.; Pardo Ruiz,Zenia;
Revista Cubana de Farmacia , 2007,
Abstract: a high resolution liquid chromatography method was validated to study the stability of loratidine syrup 0.1 %. the calibration curve in the range from 13.6 to 3.36 μg/ml was lineal, with a coefficient of correlation equal to 0.99975. the intercept and slope statistical test was not significant. the recovery obtained was 100.2 % in the concentration range studied, and the cochran and student (t) tests results were not important. the variation coefficient in the repeatability study was equal to 0.41 % for 10 replications assayed, whereas in the reproducibility fischer and student tests were not remarkable. the method proved to be specific, lineal, accurate, and exact.
DESARROLLO DE UNA ONTOLOGíA EN EL CONTEXTO DE LA WEB SEMáNTICA A PARTIR DE UN TESAURO DOCUMENTAL TRADICIONAL
Guzmán Luna,Jaime A; Torres Pardo,Durley; López García,Alba Nubia;
Revista Interamericana de Bibliotecología , 2006,
Abstract: a thesaurus is a documentary tool that is used to catalog and retrieve information in specialized environments. in the search for better alternatives in the representation of information resources, ontologies-in the context of the semantic web-are being seen as a new means of representing the knowledge that currently exists in thesauri, now that it has been demonstrated that ontologies make it possible to improve the precision and the reutilization of all kinds of knowledge. the objective of this work is to present an option for the migration of the traditional documentary thesaurus to ontology in the environment of the semantic web, with the objective of permitting its use in document retrieval.
SABIOS: una aplicación de la Web semántica para la gestión de documentos digitales
Guzmán Luna,Jaime A.; Torres Pardo,Durley; Ovalle,Demetrio A.;
Revista Interamericana de Bibliotecología , 2007,
Abstract: the semantic web seeks to convert information into knowledge. to do so, it must be based fundamentally on semantic and descriptive markings not only of the documents but the data as well, by means of automatically structured and legible information that provides the machines with a greater capacity for managing and retrieving the data. sabios proposes to introduce emergenttechnologies based on semantics and combined with multi-agent systems and information retrieval techniques in order to improve the processes of insertion, cataloging, and retrieval of digital documents, thereby implementing a system composed of three modules: a knowledge module, a semantic search module, and finally a module for visualizing and navigating the results
Validación del método analítico para el estudio de estabilidad del inyectable de clonazepam 1 mg/mL Validationof the analytical method for the stability study of clonazepam injection 1 mg/mL
Caridad M García Pe?a,Zenia Pardo Ruiz,Leonid Torres Amaro,Adriana Mu?oz Cernada
Revista Cubana de Farmacia , 2004,
Abstract: Se validó el método analítico desarrollado para el estudio de estabilidad en la cuantificación de clonazepam inyectable 1 mg/mL por cromatografía líquida de alta resolusión con detección ultravioleta a 310 nm. La curva de calibración se realizó en el rango de 20,8 a 43,2 μg/mL, la cual fue lineal con un coeficiente de correlación igual a 0,99624; la prueba estadística para el intercepto y la pendiente se consideró no significativa. Se obtuvo un recobrado del 99,6 % en el rango de concentración estudiado y las pruebas de Cochran′(G) y Student′s (t) resultaron no significativas. El coeficiente de variación en el estudio de la repetibilidad se comportó igual a 0,69 % para 10 réplicas ensayadas, mientras que en los análisis de la precisión intermedia las pruebas de Fischer y Student fueron no significativas. El método se cosidera específico, lineal, preciso y exacto. The analytical method developed by the stability study in the quantification of injectable clonazepam 1 mg/mL was validated by high resolution liquid chromatography with ultraviolet detection at 310 nm. The calibatrion curve was performed in the range from 20.8 to 43.2 mug/mL, which was lineal, with a correlation coefficient equal to 0.99624. The statistical test for the interval and the slope was considered as non significant. It was attained a recovery of 99,6 % in the studied concentration range. Cochran (G) and Student's (t) tests were not important. The variation coefficient in the repeatability study was equal to 0.69 % for 10 tested replicas, whereas Fischer and Student's tests were not significant in the analysis of intermediate precision. The method was considered specific, lineal, accurate and exact.
Método analítico por cromatografía líquida de alta resolución para el estudio de estabilidad del jarabe de loratadina 0,1 % Analytical method by high resolution liquid chromatography for the stability study of loratidine syrup 0.1 %
Leonid Torres Amaro,Caridad M. García Pe?a,Zenia Pardo Ruiz
Revista Cubana de Farmacia , 2007,
Abstract: Se validó un método de cromatografía líquida de alta resolución para el estudio de estabilidad del jarabe de loratadina 0,1 %. La curva de calibración en el rango de 13,6 a 3,36 μg/mL fue lineal, con un coeficiente de correlación igual a 0,99975; la prueba estadística para el intercepto y la pendiente, no significativa. El recobrado obtenido resultó de 100,2 % en el rango de concentración estudiado, y las pruebas de Cochran y Student (t), no significativas. El coeficiente de variación en el estudio de repetibilidad fue igual a 0,41 % para 10 réplicas ensayadas, mientras que en la reproducibilidad las pruebas de Fischer y Student, no significativas. El método resultó específico, lineal, preciso y exacto. A high resolution liquid chromatography method was validated to study the stability of loratidine syrup 0.1 %. The calibration curve in the range from 13.6 to 3.36 μg/mL was lineal, with a coefficient of correlation equal to 0.99975. The intercept and slope statistical test was not significant. The recovery obtained was 100.2 % in the concentration range studied, and the Cochran and Student (t) tests results were not important. The variation coefficient in the repeatability study was equal to 0.41 % for 10 replications assayed, whereas in the reproducibility Fischer and Student tests were not remarkable. The method proved to be specific, lineal, accurate, and exact.
Macrophage and Nitric Oxide in the american Tripanosomiasis
María Eugenia Cardenas Angelone,Diego Torres Due?as,Manuel Jose Pardo Cobos
MedUNAB , 2000,
Abstract:
EDICIóN N° 7 COMPLETA (Enero-Junio 2012)
INGRID DURLEY TORRES PARDO
Lámpsakos , 2012,
Abstract: Edición 7 del primer semestre del a o 2012
EDICIóN N° 8 COMPLETA (Julio-Diciembre 2012)
INGRID DURLEY TORRES PARDO
Lámpsakos , 2012,
Abstract: Contiene 7 artículos de calidad científica, con resultados de investigaciones en las áreas de ingeniería informática y de sistemas, con aplicaciones en diversas temáticas relacionadas con las ramas de la ingeniería Director = Jorge Mario Gaviria Editora = Ingrid Torres
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