ENVIRONMENTALLY FRIENDLY PROCESSING OF LEAD FREE SODIUM POTASSIUM NIOBATE THICK FILMS BY ELECTROPHORETIC DEPOSITION

When looking for industrial applications environmental compatible solutions are highly desired. When looking at microelectronics miniaturization, functionalization and performance are also highly required. When looking at technologies for deposition of thick films electrophoretic deposition (EPD) is attracting increasing interest for a wide range of technical applications due to its high flexibility, low cost and simplicity of management, facility to fabricate intricate shapes and to be scaled-up for large volume fabrication. Within this context in this work aqueous based electrophoretic deposition (EPD) of lead free sodium potassium niobate (KNN) is demonstrated. The goal of our work is to establish the range of conditions in which aqueous deposition of KNN films is possible. By the use of a relatively environmental friendly additive, such as sodium dodecyl sulfate (SDS), high quality crack and defect free KNN films are prepared. The deposition mechanism and the electromechanical performance of these films are presented and discussed. KNN thick films on metallic substrates with thickness varying between 10 - 15 µm have dielectric permittivity of 495, dielectric losses of 0.08 at 1 MHz and a piezoelectric coefficient d33 of ~70 pC/N. At TC (≈405 °C), these films exhibit a relative permittivity of 2166 and loss tangent of 0.11 at 1 MHz. A comparison of the physical properties between these films and their bulk ceramics counterparts demonstrates the impact of aqueous based EPD technique for the preparation of lead free ferroelectric thick films. This opens the door to the possible development of high-performance, lead-free piezoelectric thick films by a sustainable low cost process, expanding the applicability of lead free piezoelectrics. Please click Additional Files below to see the full abstract

Staining techniques for ageing tope shark, Galeorhinus galeus (Linnaeus, 1758), from the Azores : a comparison based on precision analysis.

A vertebrae sample of tope shark, Galeorhinus galeus (Linnaeus, 1758), stratified by sizeclasses,was used to test between different staining techniques of enhancing vertebral growth ring visibility. Four techniques were tested: alizarin red, silver nitrate and cobalt nitrate staining, and the “deep-coned vertebrae” technique. The latter was discarded due to its unsuitability for tope shark vertebrae. The cobalt nitrate original protocol was modified. Upon staining, each vertebra was subject to three replicated independent readings, by a single reader. Within-reader consistency and bias of growth ring counts determination were evaluated using four different precision indices: percent of agreement (PA), average percent error (APE), coefficient of variation (V) and index of precision (D). Results indicated that the vertebrae stained with the cobalt nitrate technique showed both better optic enhancement of growth rings and higher degree of count consistency, comparatively to the alizarin red and silver stained vertebrae. Conclusively, the cobalt nitrate was the most efficient staining technique upon tope shark vertebrae, among the methods tested herein

Effect of Different Modelling Assumptions on the Seismic Response of RC Structures

The introduction of new regulations for seismic assessment of structures established stricter performance requirements for existing buildings. In order to account for the poor seismic behaviour of such buildings, recent seismic codes, namely Eurocode 8 (EC8), introduce a number of prescriptions regarding issues such as analysis type, load distribution, accidental eccentricity, etc. At the same time, these codes give room for engineering judgment to be used with reference to the definition of structural and non-structural elements such as slabs or infill walls, and obviously leave the modelling assumptions, such as Finite Elements typology, meshing, mass modelling, etc. to the analyst decision. As such, four existing RC buildings, representative of traditional Mediterranean construction, considering different modelling assumptions, were subjected to an extensive number of nonlinear static analyses. The interpretation of possible deviations in the results will hopefully provide indications on the relative importance of each modelling parameter or decision.N/

New records and notes on little known shrimps (Crustacea, Decapoda) from Azorean waters.

Five species of shrimps (Crustacea, Decapoda) are recorded for the first time from the Azores: Funchalia villosa (Bouvier, 1905), Parapasiphae sucatifrons S.I. Smith, 1884 Heterocarpus ensifer A. Milne-Edwards, 1881, Heterocarpus laevigatus Bate, 1888 and Plesionika williamsi Forest, 1964. The variability of Plesionika gigliolii (Senna, 1903) and its relationship with P. sindoi (Rathbun, 1906) are discussed

Annotated list of fishes caught by the R/V ARQUIPÉLAGO off the Cape Verde archipelago.

A prospective survey was carried out in October - November of 2000, in the Cape Verde archipelago, by the R/V ARQUIPÉLAGO. The main objective was to determine the species composition and relative abundance of the demersal fish resources living in the waters of the Cape Verde archipelago. A list of fishes caught with bottom longline during the survey is presented in this document, along with information about the area, depth limits and the relative abundance of the species in the catches. Ninety-seven different species from 49 families were identified from 20 long-line sets. To our knowledge, the following 12 species were recorded for the first time from the waters of Cape Verde islands: Etmopterus princeps, Etmopterus pusillus, Gymnothorax maderensis, Myroconger compressus, Laemonema robustum, Beryx splendens, Scorpaena elongata, Serranus atricauda, Taractes rubescens, Taracthichthys longipinnis, Pagrus africanus and Cathidermis sufflamen. The species Laemonema robustum, were new to the CLOFETA area

Modelação da dispersão longitudinal em sistemas fluviais : casos de estudo

O estudo da hidrodinâmica e dispersão de descargas poluentes em sistemas fluviais assume particular relevância no estabelecimento de esquemas de gestão integrada da água em bacias hidrográficas, visando a protecção dos ecossistemas aquáticos e tendo em consideração os usos aí existentes. O presente trabalho teve como objectivo a determinação de parâmetros capazes de traduzir as características dispersivas em trechos de dois sistemas fluviais distintos. Para esse efeito, foram realizadas campanhas de amostragem num trecho do Rio Mondego e numa albufeira internacional do Rio Douro, em que se recorreu à injecção de um marcador (rodamina WT). Os resultados obtidos serviram de base à calibração e validação de um modelo de advecção-difusão com capacidade para descrever a evolução da concentração de substâncias conservativas nesses meios hídricos. Neste artigo apresenta-se a metodologia utilizada, os resultados experimentais obtidos numa das campanhas de amostragem, a atenuação dos picos de concentração em função dos tempos de percurso e a sua comparação com os resultados dos modelos matemáticos de simulação do fenómeno de dispersão longitudinal

Tracer experiments for dispersion modelling in river Douro water quality management

Parameters estimation for in situ dispersion river water behaviour characterisation, and performance evaluation of numerical models, applied to reproduce data field obtained from dye tracer experiments, were the main purposes of this research work. A monitoring program was carried out using tracer injection to assess the environmental impact of accidental pollutant discharges in an international reach of river Douro, between Castro dam (Spain) and Miranda dam (Portugal). This paper presents the methodology used in the tracer experiments, the concentration-time curves, describing dye tracer spread, the results of different simulation and their agreement with the measured data, and peak attenuation with dye spread travel time. Longitudinal dispersion coefficients values are estimated according to the river hydrodynamics

Comparision of numerical techniques solving longitudinal dispersion problems in the river Mondego

Judicious selection of mathematical models for application in a specific river basin management can mitigate prediction uncertainty. Therefore, intervention times will be established with better reliability and alarm systems could efficiently protect the aquatic ecosystems and the public health. The main purpose of this paper is to evaluate the performance of different numerical techniques when applied to river water systems dispersion modelling. A case study was developed to assess the environmental impact of Urgeiriça mining waters in a Mondego river reach, between Caldas da Felgueira and Aguieira reservoir. A monitoring program was carried out using tracer injection (rhodamine WT) to determine the in situ dispersion river water behaviour. The present work describes the methodology used in the tracer experiments, presents the concentration-time curves obtained and the performance of finite difference method (FDM) and finite element method (FEM) in a simplified river system, and compares the results of different numerical techniques application for longitudinal dispersion coefficient estimation in this river reach. The application of DUFLOW package, that includes hydrodynamics and water quality models, showed the best agreement with experimental data, allowing a reasonable support for impact assessment of different discharges scenarios in the river water quality

Modelação da hidrodinâmica e da dispersão longitudinal no rio Mondego

A selecção criteriosa de modelos atemáticos, a aplicar numa bacia específica, pode mitigar a incerteza na previsão de tempos de intervenção, aumentando a eficiência dos sistemas de protecção desses ecossistemas aquáticos. O presente trabalho teve como objectivos a determinação de parâmetros capazes de traduzir as características de dispersão num trecho do rio Mondego e a avaliação do desempenho de diferentes técnicas e métodos numéricos aplicados na modelação das características dispersivas deste rio. Para esse efeito realizaram-se três campanhas de amostragem, recorrendo-se à injecção de um marcador (rodamina WT), monitorizando-se a evolução da sua concentração em secções pré-definidas no trecho entre Caldas da Felgueira e a albufeira da barragem da Aguieira. Os resultados experimentais serviram de base à calibração de diferentes modelos de simulação e à validação do modelo com melhor ajuste aos dados experimentais (Duflow). Neste trecho obtiveram-se coeficientes de dispersão médios de 35 m2/s e 60 m2/s, para caudais de 40 e 140 m3/s, respectivamente. A percentagem de massa de rodamina recuperada nas várias estações variou entre 55 e 65%

Low-temperature dielectric measurements of confined water in porous granites

The dielectric behavior of rocks affected by the known phase transition of supercooled water is the main problem we analyzed. Three different granitic rocks were used to perform dielectric measurements in the frequency range from 100 Hz to 1 MHz and temperatures 100–350 K. Thin cylindrical samples were prepared, and circular electrodes were established using silver conductive paint. A clear change in the dielectric measurements appears at T∼220K for one of the samples. This coincides with the known phase transition of supercooled water. Tightly bounded water confined in the pores of the rock do not crystallize at 273 K, but form a metastable liquid down to 200–220 K maintaining water polarization. Below this temperature, water molecules solidify and polarizability decreases. The rock presenting the most sizable change has a very low specific surface area of ∼0.09m2g−1, has connected porosity of ∼1.10%, and has the smallest degree of alteration. In addition, geochemical analyzes reveal a low percentage of hydration water in its structure confirming the role of pore water in this change. A comparison between water-saturated, oven-dried, and vacuum-dried samples was done. Finally, a logarithmic dependency of the critical temperature for the supercooled water phase transition with the measuring frequency was found