Space-selective co-precipitation of silver and gold nanoparticles in femtosecond laser pulses irradiated Ag+, Au3+ co-doped silicate glass

We report on space-selective co-precipitation of silver and gold nanoparticles in Ag+, Au3+ co-doped silicate glasses by irradiation of femtosecond laser pulses and subsequent annealing at high temperatures. The color of the irradiated area in the glass sample changed from yellow to red with the increase of the annealing temperature. The effects of average laser power and annealing temperature on precipitation of the nanoparticles were investigated. A reasonable mechanism was proposed to explain the observed phenomena. (c) 2006 Elsevier Ltd. All rights reserved.

Linhas imprevistas no horizonte

Linhas Imprevistas no Horizonte é uma reflexão sobre experiências de desestabilização de um limite imaginado da paisagem, sugerido pela linha do horizonte. Este traço do pensamento é materializado através de vídeos ou objetos em operações poéticas que investigam novos olhares sobre a paisagem. São registros de gestos que se situam entre a desconstrução e a permanência dessa demarcação fictícia. Os trabalhos partem da linha enquanto elemento essencial do desenho para investigar as tensões produzidas ao redesenhar as fronteiras desestabilizadas. Aproximações, deslocamentos, superposição de imagens, espelhamentos e alteração de escalas são alguns dos recursos explorados para questionar o visível e resignificar a paisagem natural. Da mesma forma que cartografias e objetos antigos agregam novos significados às linhas que compõem paisagens poéticas. Assim os trabalhos oscilam entre o desejo de imersão no espaço para fazer fugir os limites e a necessidade de distanciar-se para ver sem perder o foco. Conceitos surgem de conexões entre a arte e a biologia e buscam repensar vivências associadas à sensação de desterritorialização. O que move o processo artístico é a reinvenção constante das identidades humanas e territoriais, associada à noção de paisagem como uma experiência do corpo no espaço

Space-selective precipitation of Au nanoparticles inside silica gel

Au colloids were prepared by irradiation with a Nd:YAG laser. Au nanoparticles were characterized by absorption spectra, transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. It is found that the wavelength of the laser has no effect on the size but the number of the Au nanoparticles. By irradiating a transparent silica gel doped with gold ions with the focused laser in the gel and subsequent exposing in air, a space-selective pattern of letter "P" consisting of Au nanoparticles was observed inside the silica gel.

Energy efficiency in trawling operations

Diurnal variation in trawl catches and its influence on energy efficiency of trawler operations are discussed in this paper, based on data on landings of a Japanese factory trawler which operated in the Indian waters during 1992-93. The factory vessel equipped for stern trawling had a length overall of 110 m, GT of 5460 and installed engine power of 5700 hp. Operations were conducted off west coast of India between 31 and 278 m depth contours, using a 80.4 m high opening bottom trawl with an adjusted vertical opening of 7.60.9 m. The catch data was grouped according to the median towing hour, by the time of the day. CPUE obtained was 3713.4 kg.h-1 for day time operations and 1536.6 kg.h-1 for night-time operations. Mean daily catches were 31367 kg.day-1 (SE: 2743) for day time operations and 9430 kg.day-1 (SE: 966) for night-time operations. Fuel consumption were 0.399 and 0.982 kg fuel.kg fish-1, respectively for day and night-time operations. Total catch and catch components such as threadfin bream, bulls eye, hairtails, trevelly, lizard fish showed significant improvement during day-time operations while swarming crabs showed a significant improvement in the night-time operations. The difference in catch rates between day and night could be attributed to diurnal variation in the spatial distribution and schooling behaviour of the catch categories, their differential behaviour in the vicinity of trawl systems under varying light levels of day and night and consequent effect on catching efficiency and size selectivity at different stages in the capture process. The results obtained in addition to its importance in the operational planning of trawling in order to realise objectives of maximising catch per unit effort and minimising fuel consumption per unit volume of fish caught, has added significance in the use of bottom trawl surveys in stock abundance estimates.