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Search Results: 1 - 10 of 335672 matches for " Andrés Cantarero "
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Effects of quantum statistics of phonons on the thermal conductivity of silicon and germanium nanoribbons
Yuriy A Kosevich,, Alexander V Savin and Andrés Cantarero
Nanoscale Research Letters , 2013, DOI: 10.1186/1556-276X-8-7
Abstract: We present molecular dynamics simulation of phonon thermal conductivity of semiconductor nanoribbons with an account for phonon quantum statistics. In our semiquantum molecular dynamics simulation, dynamics of the system is described with the use of classical Newtonian equations of motion where the effect of phonon quantum statistics is introduced through random Langevin-like forces with a specific power spectral density (color noise). The color noise describes interaction of the molecular system with the thermostat. The thermal transport of silicon and germanium nanoribbons with atomically smooth (perfect) and rough (porous) edges are studied. We show that the existence of rough (porous) edges and the quantum statistics of phonon change drastically the low-temperature thermal conductivity of the nanoribbon in comparison with that of the perfect nanoribbon with atomically smooth edges and classical phonon dynamics and statistics. The rough-edge phonon scattering and weak anharmonicity of the considered lattice produce a weakly pronounced maximum of thermal conductivity of the nanoribbon at low temperature.
Review on Polymers for Thermoelectric Applications
Mario Culebras,Clara M. Gómez,Andrés Cantarero
Materials , 2014, DOI: 10.3390/ma7096701
Abstract: In this review, we report the state-of-the-art of polymers in thermoelectricity. Classically, a number of inorganic compounds have been considered as the best thermoelectric materials. Since the prediction of the improvement of the figure of merit by means of electronic confinement in 1993, it has been improved by a factor of 3–4. In the mean time, organic materials, in particular intrinsically conducting polymers, had been considered as competitors of classical thermoelectrics, since their figure of merit has been improved several orders of magnitude in the last few years. We review here the evolution of the figure of merit or the power factor during the last years, and the best candidates to compete with inorganic materials. We also outline the best polymers to substitute classical thermoelectric materials and the advantages they present in comparison with inorganic systems.
Effects of Gamma Irradiation on the Kinetics of the Adsorption and Desorption of Hydrogen in Carbon Microfibres  [PDF]
Cesar Mota, Mario Culebras, Andrés Cantarero, Antonio Madro?ero, Clara Maria Gómez, Jose María Amo, Jose Ignacio Robla
Advances in Materials Physics and Chemistry (AMPC) , 2013, DOI: 10.4236/ampc.2013.32021
Abstract:

In this study, three types of carbon fibres were used, they were ex-polyacrylonitrile carbon fibres with high bulk modulus, ex-polyacrylonitrile fibres with high strength, and vapour grown carbon fibres. All the samples were subjected to a hydrogen adsorption process at room temperature in an over-pressured atmosphere of 25 bars. The adsorption process was monitored through electrical resistivity measurements. As conditioning of the fibres, a chemical activation by acid etching followed by γ-ray irradiation with 60Co radioisotopes was performed. The surface energy was determined by means of the sessile drop test. Both conditioning treatments are supplementary; the chemical activation works on the outer surface and the γ-irradiation works in the bulk material as well. Apparently, the most significant parameter for hydrogen storage is the crystallite size. From this point of view, the most convenient materials are those with small grain size because hydrogen is accumulated mainly in the grain boundaries.

An Approach on the Hydrogen Absorption in Carbon Black after Gamma Irradiation  [PDF]
Antonio Madro?ero, Mario Culebras, Andrés Cantarero, Clara M. Gómez, César Mota, José M. Amo, José I. Robla
Advances in Materials Physics and Chemistry (AMPC) , 2013, DOI: 10.4236/ampc.2013.37040
Abstract:

In this work, different samples of an industrial carbon black are used to study the hydrogen intake from an over pressurized atmosphere and its changes due to alteration of its level of crystallinity produced by γ-irradiation. The monitoring of the hydrogen adsorption was made by means of thermogravimetric analysis and by measurements of some electrical parameters as the Seebeck coefficient. X-ray diffraction shows that the irradiation diminishes the level of crystalline perfection. These results show interesting possibilities to use carbon black as cheap hydrogen absorbers.

 

Recubrimientos decorativos de Ti, TiN y TiO2 sobre vidrio, depositados en vacío mediante pulverización por arco eléctrico
Cantarero, A.,Ferrer, C.,Sánchez Bolinches, A.,Straumal, B.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2001,
Abstract: In a vacuum arc discharge, highly ionised species are formed, which permits an effective control of the deposition process and, particularly, to deposit Ti, TiN and TiO2 coatings on non-conducting materials like glass. Moreover, this technique allows us to position a mask between the substrates and the sheets to be coated. Another advantage of the vacuum arc technology is the low substrate temperature during the deposition. Data on the roughness, composition and corrosion resistance in architectural glass mask-coated with titanium nitride and oxide are presented and analysed in this work. A comparative analysis is made with reactive direct current sputtering and plasma enhanced chemical vapour deposition techniques. La técnica de pulverización por arco eléctrico en vacío permite un control eficaz del proceso de deposición, ya que la temperatura del sustrato permanece baja durante dicho proceso. Además, mediante esta técnica pueden llevarse a cabo recubrimientos sobre superficies no conductoras y resulta posible la utilización de máscaras de plástico, colocadas entre la fuente y el sustrato a recubrir. En este trabajo se han llevado a cabo recubrimientos de Ti, TiN y TiO2 sobre vidrio arquitectónico. Los recubrimientos se han realizado con y sin dibujos, aplicados a través de máscaras. Se han estudiado algunas características de estos recubrimientos, como son la rugosidad, composición y resistencia contra la corrosión. Los análisis se han llevado a cabo mediante técnicas de microscopía de fuerza atómica, espectroscopía Auger y ensayos electroquímicos. Finalmente, se ha realizado un análisis comparativo con resultados obtenidos mediante otras técnicas de deposición.
Magnetic Field-Induced Fano Profiles in the Absorption Coefficient of Semiconductors
V. I. Belitsky,A. Cantarero,S. T. Pavlov
Physics , 1996,
Abstract: A strongly asymmetric, Fano-like resonance profile has been found for magneto-absorption in the states of hot free electron-hole pairs scattered by defects in bulk semiconductors. The renormalization of the absorption profile, compared to that expected from the bare density of states in a high magnetic field, follows from a quasi-one-dimensional character of electronic excitations. The results are valid for absorption by the electronic states of large Landau quantum number where the Coulomb interaction should play a minor role. The resonance shape is in a good qualitattive agreement with experimental observations.
El papel de los juegos en la transmisión cultural: los poemas homéricos y las Olimpiadas en la sociedad oral griega
Cantarero, Luis
Revista de Dialectología y Tradiciones Populares , 2006,
Abstract: The author calls attention to the role played by the games in Greek oral tradition. After introducing the most general and defining traits of the games, he argues that those described in the Homeric Poems and practiced in Classical Greece —the Olympian, Pythian, Isthmian and Nemean Games— had two main functions: to provide entertainment and to construct a social order. This social order was epitomized in the values of the Homeric, Olimpian hero: noble, sportsman and amateur. La intención de este trabajo es revelar el papel de los juegos en la cultura oral griega. A modo de introducción, resumimos los rasgos más generales y característicos. Una vez situados en ese contexto general, veremos que los juegos descritos en los poemas homéricos y los que se realizaban en la Grecia clásica —Olímpicos, Píticos, ístmicos y Nemeos— tenían dos funciones primordiales: proporcionar entretenimiento y construir un orden social; orden que, como mostramos aquí, venía sintetizado por los valores que aglutinaba el héroe homérico y olímpico: el noble-deportista-amateur.
Consecuencias de la legislación en el consumo alimentario de lagartos. El caso del fardacho
Cantarero, Luis
Revista de Dialectología y Tradiciones Populares , 2001,
Abstract: The fardacho is a variety of lizard that people in the area of Pe alba (province of Huesca, Spain) used to hunt and eat. The author describes the food culture to which the eating of fardacho belonged and the reasons that caused a decrease in the number of these animals in the area. In addition, the author discusses the effects of wildlife-protecting legislation on the eating of this lizard in Pe alba. En este artículo se analiza el caso del fardacho, una variedad de lagarto que se cazaba y consumía en la zona de Pe alba (Huesca). En primer lugar, se describe la cultura alimentaria del fardacho y las razones que motivaron un descenso en el número de ejemplares de este animal. En segundo lugar, se analizan las consecuencias de la legislación sobre especies protegidas en el consumo de fardachos en Pe alba.
Eating in a Home for Children. Food Resistance in the Residence Juan de Lanuza
Luis Cantarero
Anthropology of Food , 2001,
Abstract: The basic needs of the children of the Residence Juan de Lanuza (Zaragoza, Spain) are covered by the daily amount of food they are provided with at meals. However, the tasks of the professionals who work in this Home are not restricted to feeding. One of the educational goals is to teach children socially adapted food habits, which are considered essential for the young persons’ “culturisation”. Food socialization has its roots in the ideology of the educating staff. The disciplinary system is based on the containment of deviations from normative food habits. The harshest punishment is inflicted when the child refuses to eat. The aim of this paper is to show that the resistance to food offered by the children of this Home between 6 and 12 years of age, is not due to lack of appetite but is the expression of a specific demand. Through their behaviour the children make explicit their wish to belong to a certain age group, they assert their ethnic difference, they show whether they wish to relate or not to other children or the staff, they ask for the educator’s attention to their state of mind, etc.
Twisted equivariant K-theory, groupoids and proper actions
Jose Cantarero
Mathematics , 2009, DOI: 10.1007/s00209-010-0683-8
Abstract: In this paper we define twisted equivariant K-theory for actions of Lie groupoids. For a Bredon-compatible Lie groupoid, this defines a periodic cohomology theory on the category of finite CW-complexes with equivariant stable projective bundles. A classification of these bundles is shown. We also obtain a completion theorem and apply these results to proper actions of groups.
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