Influence of ion energy and substrate temperature on the optical and electronic properties of tetrahedral amorphous carbon (ta-C) films

The properties of amorphous carbon (a-C) deposited using a filtered cathodic vacuum arc as a function of the ion energy and substrate temperature are reported. The sp3 fraction was found to strongly depend on the ion energy, giving a highly sp3 bonded a-C denoted as tetrahedral amorphous carbon (ta-C) at ion energies around 100 eV. The optical band gap was found to follow similar trends to other diamondlike carbon films, varying almost linearly with sp2 fraction. The dependence of the electronic properties are discussed in terms of models of the electronic structure of a-C. The structure of ta-C was also strongly dependent on the deposition temperature, changing sharply to sp2 above a transition temperature, T1, of ≈200°C. Furthermore, T1 was found to decrease with increasing ion energy. Most film properties, such as compressive stress and plasmon energy, were correlated to the sp3 fraction. However, the optical and electrical properties were found to undergo a more gradual transition with the deposition temperature which we attribute to the medium range order of sp2 sites. We attribute the variation in film properties with the deposition temperature to diffusion of interstitials to the surface above T1 due to thermal activation, leading to the relaxation of density in context of a growth model. © 1997 American Institute of Physics.

Relation between Stabilization Energy, Crystal Field Coefficient and the Magnetic Exchange Interaction for Tb3+ Ion

Based on a single ion model, Hamiltonian of the simplest form about magnetocrystalline anisotropy for Tb3+ ion was solved by using the numerical method. The relation between the stabilization energy, crystal field coefficient B-2(0) and the magnetic exchange interaction was studied as temperature approaches to 0 K. The results show that the stabilization energy contributed by Tb3+ is linear with crystal field coefficient B-2(0) approximately, but it is insensitive to the change of magnetic exchange interaction for the strong magnetic substances such as TbCo5, Tb2Co17 and Tb2Fe14B compounds.

The mechanical properties of an aluminum alloy by plasma-based ion implantation and solution-aging treatment

The age-strengthening 2024 aluminum alloy was modified by a combination of plasma-based ion implantation (PBII) and solution-aging treatments. The depth profiles of the implanted layer were investigated by X-ray photoelectron spectroscopy (XPS). The structure was studied by glancing angle X-ray diffraction (GXRD). The variation of microhardness with the indenting depth was measured by a nanoindenter. The wear test was carried on with a pin-on-disk wear tester. The results revealed that when the aluminum alloys were implanted with nitrogen at the solution temperature, then quenched in the vacuum chamber followed by an artificial aging treatment for an appropriate time, the amount of AIN precipitates by the combined treatment were more than that of the specimen implanted at ambient temperature. Optimum surface mechanical properties were obtained. The surface hardness was increased and the weight loss in a wear test decreased too.

Influence of liquid bridge volume on the onset of oscillation in floating-zone convection III. Three-dimensional model

An unsteady and three-dimensional model of the floating-half-zone convection on the ground is studied by the direct numerical simulation for the medium of 10 cSt silicon oil, and the influence of the liquid bridge volume on the critical applied temperature difference is especially discussed. The marginal curves for the onset of oscillation are separated into two branches related, respectively, to the slender liquid bridge and the fat liquid bridge. The oscillatory features of the floating-half-zone convection are also discussed.

Investigation of Mn-Implanted n-Si by Low-Energy Ion Beam Deposition

Mn ions were implanted to n-type Si(0 0 1) single crystal by low-energy ion beam deposition technique with an energy of 1000 eV and a dose of 7.5 x 10^{17} cm^{-2}. The samples were held at room temperature and at 300degreesC during implantation. Auger electron spectroscopy depth profiles of samples indicate that the Mn ions reach deeper in the sample implanted at 300degreesC than in the sample implanted at room temperature. X-ray diffraction measurements show that the structure of the sample implanted at room temperature is amorphous while that of the sample implanted at 300degreesC is crystallized. There are no new phases found except silicon both in the two samples. Atomic force microscopy images of samples indicate that the sample implanted at 300degreesC has island-like humps that cover the sample surface while there is no such kind of characteristic in the sample implanted at room temperature. The magnetic properties of samples were investigated by alternating gradient magnetometer (AGM). The sample implanted at 300degreesC shows ferromagnetic behavior at room temperature.

¿Recepción creativa en el III Concilio Provincial Mexicano?

Resumen: Repetidamente leemos en la historiografía la afirmación de que los concilios provinciales celebrados en la América hispánica durante el siglo dieciséis fueron una mera repetición o recepción de concilios y sínodos celebrados en el Viejo Mundo. En el presente artículo, de manera sumaria damos elementos que servirían para cuestionar esta afirmación a partir de los materiales de trabajo publicados recientemente sobre el Tercer Concilio Provincial Mexicano, celebrado en 1585.

Fernando III y el gobierno del reino

Resumen: Los cronistas del siglo XIII se han ocupado principalmente de la actividad política y militar de Fernando III, dejando en penumbra casi todo lo que se refiere a su labor como gobernante. Sin embargo, los diplomas del monarca han informado sobre su actividad legislativa. De estos asuntos nos ocupamos a partir de la documentación y las referencias cronísticas, y además de la bibliografía más reciente, en especial la publicada por E. S. Procter, Julio González, Ana Rodríguez y algunos estudios publicados en el congreso celebrado en 1998 con motivo del 750 aniversario de la conquista de Sevilla.

Anisotropic Deformation Of Polystyrene Particles By Mev Au Ion Irradiation

MeV An irradiation leads to a shape change of polystyrene (PS) and SiO2 particles from spherical to ellipsoidal, with an aspect ratio that can be precisely controlled by the ion fluence. Sub-micrometer PS and SiO2 particles were deposited on copper substrates and irradiated with Au ions at 230 K, using an ion energy and fluence ranging from 2 to 10 MeV and 1 x 10(14) ions/cm(2) to 1 x 10(15) ions/cm(2). The mechanisms of anisotropic deformation of PS and SiO2 particles are different because of their distinct physical and chemical properties. At the start of irradiation, the volume of PS particles decrease, then the aspect ratio increases with fluence, whereas for SiO2 particles the volume remains constant. (C) 2008 Elsevier B.V. All rights reserved.

Sapientia, 1948, Vol. III, nº 7 (número completo)

Contenido: Realismo intelectualista o irracionalismo caótico : nueva fórmula del dilema de la filosofía y cultura contemporánea / La Dirección – El desarrollo histórico de la filosofía y lógica medioevales del lenguaje / Martín Grabmann – F. H. Jacobi y la filosofía : un ejemplo de filosofía del sentimiento / Raymundo Paniker – Humanismo moderno y humanismo cristiano / Ricardo Fuentes Castellanos -- Bibliografía

Teología, 1965, Tomo III/1 nº 6 (número completo)

Sentido de la Acción Temporal del Cristiano. A propósito del esquema conciliar sobre “El Apostolado de los Laicos” / Pedro Geltman -- El Colegio Presbiterial. Apuntes de ayer y hoy para una comprensión del sacerdocio / Carmelo Giaquinta -- En torno a la noción de Tradición. Ensayo sistemático. Conclusión / Ricardo Ferrara -- El Crimen de Onán. Un aporte a la crítica textual de Jeremías XI, 19 / Jorge Mejía -- Los sueldos del Cabildo de Buenos Aires antes y después de la reforma de Rivadavia (1822) / Américo Tonda -- Crónica de la Facultad -- Libros recibidos

Effect of dentin tubules on the mechanical properties of dentin - part III: Numerical, analysis

Imitating a real tooth and the periodontal supporting tissues, we have established a 2D finite element model and carried out a numerical analysis based on the inhomogeneous and anisotropic (IA) stress-strain relation and strength model of dentin proposed in the preceding Parts I and II, and the conventional homogeneous and isotropic (III) model, respectively. Quite a few cases of loadings for a non-defected and a defected tooth are considered. The numerical results show that the stress level predicted by the IA model is remarkably higher than that by the III model, revealing that the effect of the dentin tubules should be taken into a serious consideration from the viewpoint of biomechanics.

Sapientia, 1948, Vol. III, nº 10 (número completo)

Contenido: Balmes, el filósofo del sentido común / La Dirección – La explicación fundamental del conocimiento humano / L. de Raeymaeker – La persona humana frente a la triple trascendencia : objetiva, real y divina: ensayo antropológico-metafísico / Octavio Nicolás Derisi – El problema de Dios / Clarence Finlayson – La concepción de la vida en Luigi Pirandello / Alma Novella Marani – Bibliografía -- Crónica

Sapientia, 1948, Vol. III, nº 8 (número completo)

Contenido: Actualidad y perennidad del tomismo / La Dirección – El conocimiento sensible según San Agustín y Santo Tomás de Aquino / F. J. Thonnard – El concepto de pasión en Santo Tomás / Guillermo Blanco – De las clases de conocimiento en orden al ser : según Cayetano en el proemio de su comentario al “De ente et essentia” de Sto. Tomás / Héctor Jorge Anderi – Notas y comentarios -- Bibliografía