beam-shaping microstructure optical fiber

Microstructure optical fiber with uniform intensity distribution of the fundamental mode is proposed. The design guide line and characteristics of this kind fiber are demonstrated. The relationship between refractive index profile and structure parameters is investigated. The mechanism of forming uniform fundamental mode in these fibers is analyzed.

Electrochemical fabrication and electronic behavior of polypyrrole nano-fiber array devices

Electrochemically active Polypyrrole (PPy) nano-fiber array device was fabricated via electrochemical deposition method using aluminum anodic oxide (AAO) membrane as template. After alkaline treatment electrochemically active PPy nano-fiber lost electrochemical activity, and became electrochemically inactive PPy. The electronic properties of PPy nano-fiber array devices were measured by means of a simple method. It was found that for an indium-tin oxide/electrochemically inactive PPy nano-fiber device, the conductivity of nano-fiber increased with the increase of voltage applied on the two terminals of nano-fiber. The electrochemical inactive PPy nano-fiber might be used as a nano-fiber switching diode. Both Au/electrochemically active PPy and Au/electrochemically inactive PPy nano-fiber devices demonstrate rectifying behavior, and might have been used for further application as nano-rectifiers. (c) 2005 Elsevier B.V. All tights reserved.

España neutral: el impacto económico de las dos guerras mundiales (1914-1945)

Durante las dos grandes guerras mundiales España adoptó una posición de no beligerancia que conllevaría a unas consecuencias y un impacto muy diferente para la economía española en uno y en otro conflicto. Por un lado España se presenta ante la Primera Guerra Mundial como una economía totalmente atrasada y agraria, mientras que con el estallido del conflicto supo aprovechar las necesidades del momento, permitiendo de esta manera un fuerte enriquecimiento. Por otro lado, en la Segunda Guerra Mundial España se encontraba totalmente destruida y con una fuerte inestabilidad, lo cual supuso que junto con las medidas autárquicas de la dictadura conllevaran a un periodo de penuria. IDIOMA: CASTELLANO