Estructura de bandas en un cristal fotónico unidimensional y bidimensional

Estructura de bandas en un cristal fotónico unidimensional y bidimensional Band structure in a photonic crystal one dimensional and two dimensional José Luis León Aguirre Universidad Nacional del Callao DOI: https://doi.org/10.33017/RevECIPeru2015.0003/ Resumen Una nueva idea se ha estado desarrollando en las últimas décadas, cuyo objetivo es lograr control de las propiedades ópticas de materiales con el fin de resolver ciertos problemas sujetos a nuevas aplicaciones, como por ejemplo: obtener materiales que respondan a las ondas de luz sobre un rango de frecuencias deseados para obtener su total reflexión. Este trabajo se enfoca en el desarrollo matemático del problema de las estructuras de bandas de un cristal fotónico, utilizando el método de expansión de ondas planas a los casos particulares de una y dos dimensiones. Abstract A new concept has been developing in recent decades, whose aim is to achieve control of the optical properties of materials in order to solve certain problems subject to new applications, such as for example: To obtain materials to meet the waves of light on a range of desired frequencies to get your total reflection. This work focuses on the mathematical development of the problem of the structures of bands of a photonic crystal, using the method of expansion of flat waves to individual cases of one and two dimensions.

Chemical modification and characterization of poly(ethylene terephthalate) surfaces for collagen immobilization

The functionalization of poly(ethylene terephthalate) (PET) surface films by reactions with multifunctional amines such as triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) was investigated. For the functionalization of PET films surface we used a new way of treatment, a “sandwich model”. Physical-chemical properties of functionalized PET films were analysed. Qualitative and quantitative determination of the introduced amine groups were examined by means of Fourier Transform Infrared Attenuated Total Reflexion (FTIR — ATR), X-ray photoelectron spectroscopy (XPS), and potentiometric titration. Gained wetting properties were determined by using contact angle measurements and thoroughly analysed by acid-base approach. In addition, surface topography was investigated by atomic force microscopy (AFM). The amount of the introduced amino groups after TETA incorporation has been found to be two times higher as compared to TEPA. Wetting properties were significantly improved after aminolysis. Surface free energy was higher for PET — TETA treated film than that observed for PET — TEPA treated which is in accordance with titration results. The collagen immobilization onto PET treated films was evidenced by using AFM and subsequently by using XPS.

Wechselwirkungen in Molekülkristallen, 157 [1, 2]. Mischkristallzüchtung und Strukturbestimmungen von Tetra(3,4-dimethylphenyl)-imidodiphosphat-Salzen mit Alkalikation- Verhältnissen K⊕/Rb⊕(1:5) und Rb⊕/Cs⊕(1:1) / Interaction in Molecular Crystals, 157 [1, 2]. Mixed Crystal Growth and Structure Determinations of Tetrakis(3,4-dimethylphenyl)-imidodiphosphate Salts with Alkali Cation Ratios K⊕/Rb⊕ (1:5) and Rb⊕/Cs⊕ (1:1)

Mixed crystals of tetrakis(3,4-dimethylphenyl)imidodiphosphate salts with alkalication ratios K⊕/Rb⊕ (1:5) and Rb⊕/Cs⊕ (1:1), (1:3) as well as (3:1) have been grown by suspending finely ground stoichiometric mixtures of alkali carbonates in toluene solutions of the strongly chelating ligand HN(PO(OR)2)2 - The cation ratios were measured by Total Reflexion X-Ray Fluorescence (TXRF) analysis and the single crystal structures of the polymeric K⊕/Rb⊕ as well as the Rb⊕/Cs⊕ imidodiphosphate salts determined by X-ray structure analysis. The selectivity of the various alkali ions for insertion in the crystal lattices of the individual imidodiphosphate salts has been confirmed by concentration-dependent crystallizations and discussed based on the structural analysis of the differing ligand conformations. The unit cell parameter dependence on the alkali cation radii provided information on van der Waals interactions between adjacent phenyl rings of the imidodiphosphate ligands and suggests the selective alkali cation insertion to be partly due to supramolecular repulsion within the lipophilic phenyl skin during the selfaggregation of the polymeric salt chains

A note on the total reflexion or transmission of surface waves in the presence of parallel obstacles

It is shown how a two-dimensional surface wave can be either totally reflected or totally transmitted in the presence of two parallel vertical barriers each containing a small gap. Total transmission of a surface wave past obstacles has been known to occur in many situations in water-wave theory, but total reflexion is a comparatively new phenomenon which could be of practical use in the design of breakwaters.

Characteristics of the fast and slow magnetosonic waves in layered plasmas

Propagation characteristics of two magnetosonic waves, the fast and slow modes, in layered plasmas with different β values are studied, where β is the ratio of plasma pressure to magnetic pressure. In the first part we consider the efficiency of wave penetration from one region to another with different β ratios, β1 and β2. In particular, the condition for the total reflexion, amplitude and phase of the reflexion and transmission coefficients at the interface are obtained for both modes. The results indicate that the range of deviation of the ratio β2/β1 from unity is very small for penetration of the slow mode, while the ratio for the fast mode covers a wide range. In the second part, the fast and slow normal modes of magnetosonic waves in layered plasmas are discussed and their phase and group velocities, and the spatial damping rate due to partial leakage of wave energy are compared between two modes. From these, it is concluded that the presence of the slow magnetosonic waves is restricted to within the high-β plasma region. Finally, application of these to the earth's magnetosphere is given qualitatively.