Demonstration of GaN/InGaN light emitting diodes on (100) beta-Ga2O3 substrates by metalorganic chemical vapour deposition

The growth and fabrication of GaN/InGaN multiple quantum well (MQW) light emitting diodes ( LEDs) on ( 100) beta-Ga2O3 single crystal substrates by metal-organic chemical vapour deposition (MOCVD) technique are reported. x-ray diffraction (XRD) theta-2 theta. scan spectroscopy is carried out on the GaN buffer layer grown on a ( 100) beta-Ga2O3 substrate. The spectrum presents several sharp peaks corresponding to the ( 100) beta-Ga2O3 and ( 004) GaN. High-quality ( 0002) GaN material is obtained. The emission characteristics of the GaN/InGaN MQW LED are measurement. The first green LED on beta-Ga2O3 with vertical current injection is demonstrated.

Intense upconversion and infrared emissions in Er3+;Yb3+ codoped Lu2 Si O5 and (Lu0.5 Gd0.5)2 Si O5 crystals

High optical quality Lu2SiO5 (LSO) and (Lu0.5Gd0.5)(2)SiO5 (LGSO) laser crystals codoped with Er3+ and Yb3+ have been fabricated by the Czochralski method. Intense upconversion (UC) and infrared emission (1543 nm) are observed under excitation of 975 nm. The luminescence processes are explained and the emission efficiencies are quantitatively obtained by measuring the UC efficiency and calculating the emission cross section. The temperature-dependent optical properties of the crystals are also investigated. Our study indicates that Er3+-Yb3+ : LSO and Er3+-Yb3+: LGSO crystals are promising gain media for developing the solid-state 1.5 mu m optical amplifiers and tunable UC lasers. (c) 2008 American Institute of Physics.

Preparation of high laser induced damage threshold antireflection film using interrupted ion assisted deposition

Single layers and antireflection films were deposited by electron beam evaporation, ion assisted deposition and interrupted ion assisted deposition, respectively. Antireflection film of quite high laser damage threshold (18J/cm(2)) deposited by interrupted ion assisted deposition were got. The electric field distribution, weak absorption, and residual stress of films and their relations to damage threshold were investigated. It was shown that the laser induced damage threshold of film was the result of competition of disadvantages and advantages, and interrupted ion assisted deposition was one of the valuable methods for preparing high laser induced damage threshold films. (c) 2007 Optical Society of America

Cantando a insatisfação: os recursos linguístico-expressivos na obra de Gonzaguinha

A fim de motivar alunos dos Ensinos Fundamental e Médio a atentarem para o cunho expressivo dos fatos da língua e buscarem conhecer os grandes nomes da música nacional, este trabalho objetivou um estudo estilístico dos recursos linguístico-expressivos de textos musicais de Luiz Gonzaga do Nascimento Jr. o Gonzaguinha. Destacou-se, primeiramente, o viés social da música. Em seguida, pretendeu-se uma aproximação entre textos musicais e o conceito de poesia para, então, tratar mais cuidadosamente do papel didático da canção. Considerando a concepção de contracultura, defendida por Marilena Chauí (1990) como o contexto histórico do momento das produções musicais, partiu-se para explanações acerca da Estilística: sua história, seus âmbitos, seu alcance e possibilidades. Por fim, adentrou-se nas relações lingüísticas a partir de canções de tom ora de protesto inconformado, ora nacionalista-apaixonado do artista mencionado. Desenvolveu-se, portanto, uma abordagem estilística individual do autor a partir de apontamentos teóricos sobre aspectos sonoros, léxico-semânticos, morfossintáticos e enunciativos do processo discursivo expressivo. Com esse intento, elegeram-se composições que ilustraram as marcas lingüísticas e seu entrelaçamento com o plano do conteúdo

Aspects of quality control of wind profiler measurements in complex topography

It is well known in the scientific community that some remote sensing instruments assume that sample volumes present homogeneous conditions within a defined meteorological profile. At complex topographic sites and under extreme meteorological conditions, this assumption may be fallible depending on the site, and it is more likely to fail in the lower layers of the atmosphere. This piece of work tests the homogeneity of the wind field over a boundary layer wind profiler radar located in complex terrain on the coast under different meteorological conditions. The results reveal the qualitative importance of being aware of deviations in this homogeneity assumption and evaluate its effect on the final product. Patterns of behavior in data have been identified in order to simplify the analysis of the complex signal registered. The quality information obtained from the homogeneity study under different meteorological conditions provides useful indicators for the best alternatives the system can offer to build wind profiles. Finally, the results are also to be considered in order to integrate them in a quality algorithm implemented at the product level.

Vanadyl arsenates as catalysts for selective oxidation of organic sulfides and alkenes

artículo científico (postprint)