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On the influence of silica type on the structural integrity of dense La9.33Si2G...

Apatite-type rare earth based oxides, such as R-doped lanthanum oxides of general formula La9.33(RO4)6O2 with R = Ge, Si, exhibit high ionic conductivity and low activation energy at moderate temperatures, when compared to the yttria-stabilized zirconia electrolyte making them potential materials to be used in the range 500–700 °C, for intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, d...

CdTe nano-structures for photovoltaic devices

CdTe nano-structures with diameter of ∼100 nm and variable length (200–600 nm) were fabricated on glass substrates covered with conductive buffer layers such as NiCr, ZAO (ZnO:Al2O3 + Ta2O5) or TiPd alloys. The fabrication process consisted of the starting vapour deposition of metal catalyst dropped layer followed by the isothermal catalyst-prompted vapour growth of CdTe nano-structured layer of controllable sh...

The earrings of Pancas treasure: Analytical study by X-ray based techniques – A...

The development of new metallurgical technologies in the Iberian Peninsula during the Iron Age is well represented by the 10 gold earrings from the treasure of Pancas. This work presents a first approach to the analytical study of these earrings and contributes to the construction of a typological evolution of the Iberian earrings. The manufacture techniques and the alloys composition were studied with three co...

Microscopy techniques for dye distribution in DSCs nanocrystalline TiO2 films

Trousseau's Syndrome Due to Asymptomatic Pancreatic Adenocarcinoma

Os autores relatam um caso de Síndrome de Trousseau, manifestado por trombose venosa migratória e embolia pulmonar, num doente de 58 anos assintomático até à data de internamento. O estudo desencadeado revela adenocarcinoma do pâncreas com metástases hepáticas, e a situação torna-se ainda mais grave após a ocorrência de um acidente vascular cerebral isquémico, aparentemente em relação com a paragem por 24 horas...

Experiments and modelling in N2-H2 capacitively coupled radio-frequency discha...

This work uses experiments and simulations to analyze the modifications induced in pure N2 capacitively coupled radio-frequency discharges, running at low pressure (0.6–1.2 mbar) and low power (5–20 W), by the addition of small amounts of H2 (up to 5%). Simulations use a hybrid code coupling a two-dimensional time-dependent fluid module, describing the dynamics of the charged particles, to a zero-dimensional ki...

Capacitively coupled radio-frequency N2 discharges at low pressures

Capacitively coupled radio-frequency discharges (ccrf) in nitrogen mixtures are frequently used for the processing, modification and functionalization of different kinds of materials. Although nitrogen plasmas have been studied for many years, and despite their growing interest in applications, there is only partial knowledge about ccrf nitrogen plasmas. This paper uses experiments and modelling to study ccrf d...

Bandwidth aspects in second generation current conveyors

This paper discusses bandwidth problems associated with second-generation current conveyors (CCII). In particular, our work is centered in high-capacitance applications, and has been oriented for wireless optical links and applied physics. We discuss techniques for improving bandwidth in these CCIIs, and develop a new CCII structure with larger bandwidth than traditional circuits. These circuits are then compar...

A low-noise CMOS front-end for TOF-PET

An analogue CMOS front-end for triggering and amplification of signals produced by a silicon photomultiplier (SiPM) coupled to a LYSO scintillator is proposed. The solution is intended for time-of-flight measurement in compact Positron Emission Tomography (TOF-PET) medical imaging equipments where excellent timing resolution is required (approximate to 100 ps). A CMOS 0.13 mu m technology was used to implement ...

General model for delayed feedback and its application to transimpedance amplif...

Delays in real systems can be of two types: i) intrinsic delays - due to the physical principles of operation of each electronic device; ii) designed delays - due to extra circuits used to add the desired delay. Previous work established the possibility of achieving bandwidth improvements using small delays inside the feedback loop of feedback amplifiers. The modeling approach followed on these contributions us...