We have developed new types of functional and smart optical silicon sensors, based on ITO/multichannel insulator/silicon structures, which are able to execute electronic functions such as amplifying the photocurrent (without avalanche multiplication), transforming the input optical signal into a radio frequency output signal and transforming the analogue input optical signal to a digital output form, without external active electronic components. These new functional optical sensors allow a substantial simplification of the registration of optical signals as well as of the electronic scheme to be used. © 1998 Elsevier Science S.A. All rights reserved.

We have developed new types of functional and smart optical silicon sensors, based on ITO/multichannel insulator/silicon structures, which are able to execute electronic functions such as amplifying the photocurrent (without avalanche multiplication), transforming the input optical signal into a radio frequency output signal and transforming the analogue input optical signal to a digital output form, without external active electronic components. These new functional optical sensors allow as substantial simplification of the registration of optical signals as well as of the electronic scheme to be used.

Mossbauer and EPR spectroscopies were used to characterize the Fe clusters in an Fe-S protein isolated from Desulfovibrio desulfuricans (ATCC 27774). This protein was previously thought to contain hexanuclear Fe clusters, but a recent X-ray crystallographic measurement on a similar protein isolated from Desulfovibrio vulgaris showed that the protein contains two tetranuclear clusters, a cubane-type [4Fe-4S] cluster and a mixed-ligand cluster of novel structure [Lindley et al. (1997) Abstract, Chemistry of Metals in Biological Systems, European Research Conference, Tomar, Portugal]. Three protein samples poised at different redox potentials (as-purified, 40 and 320 mV) were investigated. In all three samples, the [4Fe-4S] cluster was found to be present in the diamagnetic 2+ oxidation state and exhibited typical Mossbauer spectra. The novel-structure cluster was found to be redox active. In the 320-mV and as-purified samples, the cluster is at a redox equilibrium between its fully oxidized and one-electron reduced states. In the 40-mV sample, the cluster is in a two-electron reduced state. Distinct spectral components associated with the four Fe sites of cluster 2 in the three oxidation states were identified. The spectroscopic parameters obtained for the Fe sites reflect different ligand environments, making it possible to assign the spectral components to individual Fe sites. In the fully oxidized state, all four iron ions are high-spin ferric and antiferromagnetically coupled to form a diamagnetic S = 0 state. In the one-electron and two-electron reduced states, the reducing electrons were found to localize, consecutively, onto two Fe sites that are rich in oxygen/nitrogen ligands. Based on the X-ray structure and the Mossbauer parameters, attempts could be made to identify the reduced Fe sites. For the two-electron reduced cluster, EPR and Mossbauer data indicate that the cluster is paramagnetic with a nonzero interger spin. For the one-electron reduced cluster, the data suggest a half-integer spin of 9/2 Characteristic fine and hyperfine parameters for all four Fe sites were obtained. Structural implications and the nature of the spin-coupling interactions are discussed.

This work reports the structure and electro-optical characteristics of different metal oxide films obtained by spray pyrolysis on heated glass substrates, aiming their application in optoelectronic devices. The results show that this technique leads to thin films with properties ranging from dielectric to degenerate semiconductors, offering the following advantages: simplicity, low cost, high productivity and the possibility of covering large areas, highly important for large area device applications.

This paper deals with the structure, composition and electro-optical characteristics of n-type amorphous and microcrystalline silicon thin films produced by plasma-enhanced chemical vapour deposition in a hydrogenhelium mixture. In addition, special emphasis is given to the role that hydrogen incorporation plays in the film's properties and in the characteristics of n-type microcrystalline films presenting simultaneously optical gaps of about 2·3 eV (controlled by the hydrogen content in the film), a dark conductivity of 6-5S cm-1 and a Hall mobility of about 0·86 cm2 V-1 s-1, the highest combined values for n-type microcrystalline silicon films, as far as we know.

This study was produced for the “Study of Instruments and Tools to anticipate the effects of industrial change on employment, trades and vocational qualifications” and for DG V (Employment) of the European Commission in the late 1994. It started when the previous Portuguese government was still ruling, the main policies were defined, and the available instruments were not used in a minimum extend. The new Government, issued from the 1995 elections, proposed “employment” as a major objective with horizontal responsibility. That’s also why there is now a Ministry for Qualifications and Employment, and another one for Solidarity and Social Affairs, not one for Employment and Social Affairs as the previous Government had. But more than that, this objective is considered to need a coordinated and consistent action that involves external affairs, industrial and regional policies, and the policies on education, training and employment, among others. The promotion of the “quality of employment” is being recently done at the working conditions, remuneration, social protection, occupational promotion levels, and the equality of opportunities towards employment and vocational training levels, and finally, the levels of qualification of human resources for a better labour market, education policy and training policy developments. In Portugal, the influence of the industrial change is produced in a top-down way; with (in some cases) an ex post analysis process to formulated training needs. This means that the industrial change impact is produced (normally, unexpectedly), and afterwards the responsible at the company level tries to know which training needs should be formulated in order those effects could be the smoother possible. The training needs at the company level is not based on anticipatory studies, neither is done any long term forecast on qualification, or even employment level.

A survey of Hemidactylus turcicus L. (Reptilia, Gekkonidae) was carried out from March to October
of 1996, in temporally limited transects, using quadrats of 160x160 meters, in the World Heritage site
of Évora. Occasional observations were also made in 1995 and 1996. Hemidactylus turcicus is
common in the sampled area, occurring in 56% of the quadrats, and prefers quiet streets. The species
Tarentola mauritanica was not observed in Évora but it appears 10 Km to the Southwest of this town.
Diurnal activity and winter activity were not observed.

The aim of this work is to present a model to interpret the static and the dynamic detection and resolution limits of 1D thin film position sensitive detectors based on p-i-n a-Si:H devices. The model can determine the device characteristics that influence the spatial limits and the response time of the device.