808 nm high-power laser grown by MBE through the control of Be diffusion and use of superlattice

808 nm high-power laser diodes are gown by MBE. In the laser structure, the combination of Si-doped GRIN (graded-index) region adjacent to n-AlGaAs cladding layer with reduced Be doping concentration near the active region has been used to diminish Be diffusion and oxygen incorporation. As compared with the laser structure which has undoped GRIN region and uniform doping concentration for Si and Be, respectively, in the cladding layers, the slope efficiency has increased by about 8%. Typical threshold current density of 300 A/cm(2) and the minimum threshold current density of 220 A/cm(2) for lasers with 500 mu m cavity length are obtained. A high slope efficiency of 1.3 W/A for coated lasers with 1000 mu m cavity length is also demonstrated, Recorded CW output power at room temperature has reached 2.3 W.

Perfectly Hydrophobic Silicone Nanofiber Coatings: Preparation from Methyltrialkoxysilanes and Use as Water-Collecting Substrate

Perfectly hydrophobic (PHO) coatings consisting of silicone nanofibers have been obtained via a solution process using methyltrialkoxysilanes as precursors. On the basis of thermal gravimetry and differential thermal analysis (TG-DTA) and Fourier transform infrared spectroscopy (FTIR) results, the formula of the nanofibers was tentatively given and a possible growth mechanism of the nanofibers was proposed. Because of the low affinity between the coatings and the small water droplet, when using these coatings as substrate for collecting water vapor, the harvesting efficiency could be enhanced as compared with those from bare glass substrate for more than 50% under 25 degrees C and 60-90% relative humidity. By removing the surface methyl group by heat treatment or ultraviolet (UV) irradiation, the as-prepared perfectly hydrophobic surface can be converted into a superhydrophilic surface.

Pt Nanoparticles Supported on TiO2 Colloidal Spheres with Nanoporous Surface: Preparation and Use as an Enhancing Material for Biosensing Applications

An easy surface-modified method has been developed to link -NH2 groups to the TiO2 colloidal spheres with nanoporous surface (f-TiO2). It was found that the as-prepared f-TiO2 is positively charged in neutral conditions and could act as an electrostatic anchor for nanosructures with opposite charge, Furthermore, platinum nanoparticles (Pt NPs) are successfully assembled on the f-TiO2 mainly via electrostatic interaction to fabricate a new kind of Pt NPs/TiO2 hybrid nanomaterial (f-TiO2-Pt NPs). The morphology, structure, and composition of the hybrids were characterized by the means of diverse techniques such as transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and Raman spectra. Electrochemical experiments indicate the electrode modified with f-TiO2-Pt NPs shows prominent electrocatalytic activity toward the oxidation of hydrogen peroxide.

Carbon Nanotube/Silica Coaxial Nanocable as a Three-Dimensional Support for Loading Diverse Ultra-High-Density Metal Nanostructures: Facile Preparation and Use as Enhanced Materials for Electrochemical Devices and SERS

In this paper, we have reported a very simple strategy (combined sonication with sol-gel techniques) for synthesizing well-defined silica-coated carbon nanotube (CNT) coaxial nanocable without prior CNT functionalization. After functionalization with NH2 group, the CNT/silica coaxial nanocable has been employed as a three-dimensional support for loading ultra-high-density metal or hybrid nanoparticles (NPs) such as gold NPs, Au/Pt hybrid NPs, Pt hollow NPs, and Au/Ag core/shell NPs. Most importantly, it is found that the ultra-high-density Au/Pt NPs supported on coaxial nanocables (UASCN) could be used as enhanced materials for constructing electrochemical devices with high performance. Four model probe molecules (O-2, CH3OH, H2O2, and NH2NH2) have been investigated on UASCN-modified glassy carbon electrode (GCE). It was observed that the present UASCN exhibited high electrocatalytic activity toward diverse molecules and was a promising electrocatalyst for constructing electrochemical devices with high performance. For instance, the detection limit for H2O2 with a signal-to-noise ratio of 3 was found to be 0.3 mu M, which was lower than certain enzyme-based biosensors.

A Computational Model for the Acquisition and Use of Phonological Knowledge

Does knowledge of language consist of symbolic rules? How do children learn and use their linguistic knowledge? To elucidate these questions, we present a computational model that acquires phonological knowledge from a corpus of common English nouns and verbs. In our model the phonological knowledge is encapsulated as boolean constraints operating on classical linguistic representations of speech sounds in term of distinctive features. The learning algorithm compiles a corpus of words into increasingly sophisticated constraints. The algorithm is incremental, greedy, and fast. It yields one-shot learning of phonological constraints from a few examples. Our system exhibits behavior similar to that of young children learning phonological knowledge. As a bonus the constraints can be interpreted as classical linguistic rules. The computational model can be implemented by a surprisingly simple hardware mechanism. Our mechanism also sheds light on a fundamental AI question: How are signals related to symbols?

Levantamento pedológico de uma área-piloto relacionada ao Projeto BiosBrasil (Conservation and Sustainable Management of Below-Ground Biodiversity: Phase I), município de Benjamin Constant (AM): janela 6.

2005

Solos das áreas-piloto do Projeto BiosBrasil (Conservation and Sustainable Management of Below-Ground Biodiversity: Phase I), Município de Benjamin Constant, Estado do Amazonas.

2005

Levantamento pedológico de uma área-piloto relacionada ao Projeto BiosBrasil (Conservation and Sustainable Management of Below-Ground Biodiversity: Phase I), Município de Benjamin Constant (AM): Janela 6

2005

Solos das áreas-piloto do Projeto BiosBrasil (Conservation and Sustainable Management of Below-Ground Biodiversity: Phase I), Município de Benjamin Constant, Estado do Amazonas

2005

Levantamento pedológico de uma área-piloto relacionada ao projeto BiosBrasil (Conservation and Sustainable Management of Below-Ground Biodiversity: Phase I), Município de Benjamin Constant (AM): janela 6.

2005

Solos das áreas-piloto do projeto BiosBrasil (Conservation and Sustainable Management of Below-Ground Biodiversity: Phase I), município de Benjamin Constant, Estado do Amazonas.

2005

Levantamento do Uso e Cobertura da Terra de Seis Áreas Amostrais Relacionadas ao Projeto BiosBrasil (Conservation and Sustainable Management of Below-Ground Biodiversity:Phase I), Município de Benjamin Constant (AM).

2005

Uptake and use of electronic information services: trends in UK higher education from the JUSTEIS project

Urquhart, C., Lonsdale, R.,Thomas, R., Spink, S., Yeoman, A., Armstrong, C. & Fenton, R. (2003). Uptake and use of electronic information services: trends in UK higher education from the JUSTEIS project. Program, 37(3), 167-180. Sponsorship: JISC