Últimos itens adicionados do Acervo: Laboratório Nacional de Energia e Geologia

O Laboratório Nacional de Energia e Geologia (LNEG) é uma instituição de I&D orientada para responder às necessidades da sociedade e das empresas. Apostando numa investigação sustentável e para a sustentabilidade através da geração do conhecimento em Portugal.

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‣ Preliminary account of the Silurian carbon isotope record from the Barrancos region, Ossa Morena Zone, Portugal

Lopes, Gilda; Fernandes, Paulo; Goodhue, Robbie; Pereira, Zélia; Piçarra, José Manuel
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /08/2011 Português

‣ Isotope geochemistry of São Tomé Island (Cameroon Volcanic Line) : implications for mantle source components

Lopes, J. M. R.; Caldeira, Rita; Cordani, Umberto G.; Munhá, José
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /08/2011 Português

‣ Facing confrontation in coaxial deformation during the main Variscan tectonic event : SW Portuguese sector of Centro-Iberian Zone

Metodiev, Daniel; Romão, José Manuel; Dias, Rui; Ribeiro, António
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2011 Português

‣ Morphological and chemical characterization of mineral concretions in the freshwater bivalve Anodonta cygnea (Unionidae)

Hinzmann, Mariana F.; Lima, Manuel Lopes; Bobos, Iuliu; Ferreira, Jorge Amaral; Domingues, Bernardo; Machado, Jorge
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em /01/2015 Português
The freshwater mussel Anodonta cygnea is commonly used as a model organism for biomineralization studies, its peculiar morphofunctional properties also make it an excellent environmental biomonitor. The first detailed on the calcareous concretions from gill and mantle tissue, as well as fluids of the freshwater bivalve A. cygnea, supported by histological, scanning, spectrometry, and spectroscopy analyses. Through these analyses, the morphology, structure, and chemical characterization of these biomineral concretions were accomplished. The concretions represent a high percentage of the dry weight of these organisms. In gill tissue, it can reach up to 50% of dry weight prior to reproductive maturity. Analysis of elemental composition of the tissue concretions showed the presence of calcium and phosphate, as main components, associated with other residual elements like iron, manganese, magnesium, and zinc. Concretions are arranged in concentric alternated layers of organic and inorganic matrix. The shape and size of the concretions vary substantially, from very small, less than 1 µm diameter with very regular round structure, found mainly in the mantle tissue, to more than 50 µm length with irregular globular clusters...

‣ Novel Li3ClO based glasses with superionic properties for lithium batteries

Braga, M. H.; Ferreira, Jorge Amaral; Stockhausen, V.; Oliveira, J. E.; El-Azab, A.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em /04/2014 Português
Three types of next generation batteries are currently being envisaged among the international community: metal-air batteries, multivalent cation batteries and all-solid-state batteries. These battery designs require high-performance, safe and cost effective electrolytes that are compatible with optimized electrode materials. Solid electrolytes have not yet been extensively employed in commercial batteries as they suffer from poor ionic conduction at acceptable temperatures and insufficient stability with respect to lithium-metal. Here we show a novel type of glasses, which evolve from an antiperovskite structure and that show the highest ionic conductivity ever reported for the Li-ion (25 mS cm-1 at 25 °C). These glassy electrolytes for lithium batteries are inexpensive, light, recyclable, non-flammable and non-toxic. Moreover, they present a wide electrochemical window (higher than 8 V) and thermal stability within the application range of temperatures.

‣ Biomineralization studies on cellulose membrane exposed to biological fluids of Anodonta cygnea

Lopes, Anabela; Lima, Manuel Lopes; Ferreira, Jorge Amaral; Araújo, Sandra; Hinzmann, Mariana F.; Oliveira, José; Rocha, António; Domingues, Bernardo; Bobos, Iuliu; Machado, Jorge
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em /06/2014 Português
The present work proposes to analyse the results obtained under in vitro conditions where cellulose artificial membranes were incubated with biological fluids from the freshwater bivalve Anodonta cygnea. The membranes were mounted between two half ‘Ussing chambers’ with different composition solutions in order to simulate epithelial surfaces separating organic fluid compartments. The membrane surfaces were submitted to two synthetic calcium and phosphate solutions on opposite sides, at pH 6.0, 7.0 or 9.0 during a period of 6 hours. Additional assays were accomplished mixing these solutions with haemolymph or extrapallial fluid from A. cygnea, only on the calcium side. A selective ion movement, mainly dependent on the membrane pore size and/or cationic affinity, occurred with higher permeability for calcium ions to the opposite phosphate chamber supported by calcium diffusion forces across the cellulose membrane. In general, this promoted a more intense mineral precipitation on the phosphate membrane surface. A strong deposition of calcium phosphate mineral was observed at pH 9.0 as a primary layer with a homogeneous microstructure, being totally absent at pH 6.0. The membrane showed an additional crystal phase at pH 7.0 exhibiting a very particular hexagonal or cuttlebone shape...

‣ Dual-mode cultivation of Chlorella protothecoides applying inter-reactors gas transfer improves microalgae biodiesel production

Santos, Carla A.; Nobre, Beatriz P.; Silva, Teresa Lopes da; Pinheiro, H. M.; Reis, Alberto
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Chlorella protothecoides, a lipid-producing microalga, was grown heterotrophically and autotrophicallyin separate reactors, the off-gases exiting the former being used to aerate the latter. Autotrophic biomass productivity with the two-reactor association, 0.0249 g L-1h-1, was 2.2-fold thevalue obtained in a control autotrophic culture, aerated with ambient air. Fatty acid productivity was1.7-fold the control value. C. protothecoides heterotrophic biomass productivity was 0.229 g L-1h-1. This biomass’ fatty acid con-tent was 34.5% (w/w) with a profile suitable for biodiesel production, according to European Standards.The carbon dioxide fixed by the autotrophic biomass was 45 mg CO2L-1h-1in the symbiotic arrange-ment, 2.1 times the control reactor value.The avoided CO2 atmospheric emission represented 30% of the CO2 produced in the heterotrophic stage, while the released O2 represented 49% of the oxygen demand in that stage.Thus, an increased efficiency in the glucose carbon source use and a higher environmental sustainability were achieved in microalgal biodiesel production using the proposed assembly.

‣ Production of bio-hydrocarbons by hydrotreating of pomace oil

Pinto, Filomena; Varela, F. T.; Gonçalves, Margarida; André, Rui Neto; Costa, Paula; Mendes, Benilde
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Olive pomace oil is a by-product from the olive oil industry that is still being used in the food industry as a low value vegetable oil. Crude olive pomace oil needs to be refined and is blended with virgin olive oils before being used as edible oil. The detection of toxic compounds led to more restricted legislation and to the search of alternative valorisation processes, such as hydrotreating to obtain bio-hydrocarbons. Hydrotreating of olive pomace oil at moderate temperatures (from 300 to 430 C) and in presence of initial hydrogen pressure of 1.1 MPa led to triglycerides destruction and to their conversion into a large range of organic compounds with predominance to hydrocarbons. Even without any catalyst, conversions into hydrocarbons were always higher than 90% (v/v). Catalyst presence, such as: CoMo/Al2O3, FCC (fluid catalytic cracking) or HZSM-5 changed hydrogenated liquids composition. The highest content of alkanes was obtained with CoMo catalyst, while FCC and HZSM-5 led to the highest contents of aromatic compounds. The results obtained showed that olive pomace oil can be efficiently converted into bio-hydrocarbons with a wide range of applications. It was also studied the effect of pyrolysing olive pomace oil prior to its hydrotreating. Pyrolysis pre-treatment seems to have favoured hydrotreating process by promoting initial cracking reactions. Thus...

‣ Conversion of cellulosic materials into glycolipid biosurfactants, mannosylerythritol lipids, by Pseudozyma spp. under SHF and SSF processes

Faria, Nuno Torres; Santos, Marisa V.; Ferreira, Carla; Marques, Susana; Ferreira, Frederico C.; Fonseca, César
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Background: Mannosylerythritol lipids (MEL) are glycolipids with unique biosurfactant properties and are produced by Pseudozyma spp. from different substrates, preferably vegetable oils, but also sugars, glycerol or hydrocarbons. However, solvent intensive downstream processing and the relatively high prices of raw materials currently used for MEL production are drawbacks in its sustainable commercial deployment. The present work aims to demonstrate MEL production from cellulosic materials and investigate the requirements and consequences of combining commercial cellulolytic enzymes and Pseudozyma spp. under separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes. Results: MEL was produced from cellulosic substrates, Avicel® as reference (>99% cellulose) and hydrothermally pretreated wheat straw, using commercial cellulolytic enzymes (Celluclast 1.5 L® and Novozyme 188®) and Pseudozyma antarctica PYCC 5048T or Pseudozyma aphidis PYCC 5535T. The strategies included SHF, SSF and fed-batch SSF with pre-hydrolysis. While SSF was isothermal at 28°C, in SHF and fed-batch SSF, yeast fermentation was preceded by an enzymatic (pre-)hydrolysis step at 50°C for 48 h. Pseudozyma antarctica showed the highest MEL yields from both cellulosic substrates...

‣ Spatial diffusion and the formation of a technological innovation system in the receiving country: The case of wind energy in Portugal

Bento, Nuno; Fontes, Margarida
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
This paper investigates how energy technologies diffuse spatiallythrough the examination of wind growth in Denmark (core) andPortugal (follower). The research draws on the empirical his-torical scaling dynamics to compare patterns of diffusion, andproposes an explanation for these patterns with the help of thetechnological innovation systems (TIS) theoretical framework. Theanalysis uncovered an acceleration of diffusion when the technol-ogy attained the new market. The mechanisms that allowed rapidadoption were found to be, among others, transnational linkagesand an improved absorptive capacity. The latter benefited frompast investments in knowledge development, imports of state-of-the-art technology and construction of a local industry assemblingavailable competencies. Targeted policies (e.g. tender-based feed-in scheme) were effective to stimulate technology transfer andboost diffusion. The linkages with the global TIS and the conceptof absorptive capacity improve the understanding of the processesinvolved in the formation of a TIS in receiving countries.

‣ Mobilized to access key resources at early stages of biotech firms: a comparative analysis in two moderately innovative countries

Capaldo, Guido; Fontes, Margarida; Cannavacciuolo, Lorella; Rippa, Pierluigi; Sousa, Cristina
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
This paper investigates the networking behaviour of biotechnology start-ups in peripheral locations. The aim is to understand whether the conditions found in this type of environment introduce some specificities in the networking process, namely in network building and early mobilization to access key resources. The paper compares biotechnology start-ups in Portugal and in Southern Italy, focusing on relationships with research organizations and on the relevance assumed by international connections, and investigating the role played by entrepreneurs’ personal networks. The research identified some common features that diverge from the typical biotechnology start-up behaviour and can be regarded as firms’ adaptive responses to the conditions faced. Notwithstanding the frequent presence of close connections with local research organizations—that often play functions that go much beyond that of a knowledge source—the local environment is a lesser determinant for a substantial proportion of firms than would be expected in start-ups. A distinctive feature of these firms is an extensive reliance on foreign sources, for different purposes and from the very early stages. Entrepreneurs’ personal networks are found to be instrumental...

‣ Impact of weather regimes on the wind power ramp forecast in Portugal

Couto, A.; Costa, P.; Rodrigues, L.; Lopes, Vitor V.; Estanqueiro, Ana
Fonte: Institute of Electrical and Electronics Engineers - IEEE Publicador: Institute of Electrical and Electronics Engineers - IEEE
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Short-term forecasting and diagnostic tools for severe changes of wind power production (power ramps) may provide reliable information for a secure power system operation at a small cost. Understanding the underlying role of the synoptic weather regimes (WRs) in triggering the wind power ramp events can be an added value to improve and complement the current forecast techniques. This work identifies and classifies the WRs over mainland Portugal associated with the occurrence of severe wind power ramps. The most representative WRs are identified on compressed surface level atmospheric data using principal component analysis by applying K-means clustering. The results show a strong association between some synoptic circulation patterns and step variations of the wind power production indicating the possibility to identify certain WRs that are prone to trigger severe wind power ramps, thus opening the possibility for future development of diagnostic warning systems for system operators’ use.

‣ Wind resource assessment method for floating deep offshore wind turbines

Estanqueiro, Ana; Couto, A.; Rodrigues, L.; Marujo, R.
Fonte: Institution of Engineering and Technology - IET Publicador: Institution of Engineering and Technology - IET
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
This study presents a new methodology for the assessment of the wind energy resource at deep offshore locations where the use of floating wind turbines is foreseen. The wind resource assessment methodology developed follows the principles used by IEC 61400-12-1 standard in general and proposes the use of experimental data from a floating light detection and ranging (LIDAR) system on a deep offshore region – that assumes the role of the ‘temporary mast’ – and a coastal meteorological mast installed onshore acting as the ‘permanent met mast’. The methodology takes into consideration the time shift between the locations of the two measurement points and the wind direction associated with different atmospheric phenomena. The results obtained conclude that the methodology increases the accuracy of the wind resource assessment campaign while reducing the involved costs and technical risks. An added advantage is the possibility of extending this methodology for the evaluation of the power performance of floating wind turbines during the operational phase of the power plant.

‣ Production of drinking water using a multi-barrier approach integrating nanofiltration: a pilot scale study

Lopes, Mafalda T. P.; Matos, Cristina T.; Pereira, Vanessa J.; Benoliel, Maria J.; Valério, Maria Ermelinda; Bucha, Luís B.; Rodrigues, Alexandre; Penetra, Ana I.; Ferreira, Elisabete; Cardoso, Vitor; Reis, Maria A. M.; Crespo, João G.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
A multi-barrier system was studied for the production of drinking water with high chemical and microbiological quality. The integration of nanofiltration (NF) and ultraviolet (UV) photolysis was tested at pilot scale in a surface water treatment plant. The NF membranes tested, Desal DK and NF270, allow for the production of permeates with high quality standards, although the membrane with higher molecular weight cut-off (NF270) revealed to be the best option for surface water treatment due to its higher permeability. The NF270 membrane was also efficient to deliver high quality water, even under high pollutant concentrations, making possible to operate with water recovery rates as high as 98%. Extensive studies were performed in the water treatment plant where the proposed system was tested at three locations of the drinking water production line. Seeking to achieve the best compromise between high recovery rate, high retention of chemicals and microorganisms as well as preventing operational problems (flux decline and fouling), it was found that the integrated system should be placed after the conventional sand filtration, operating at a 91% recovery rate. Under the selected conditions – TMP of 8 bar and recovery rate of 91% – it is possible to operate at constant permeability without flux decline for a period of 15 days...

‣ Dynamic testing of systems – use of TRNSYS as an approach for parameter identification

Almeida, P.; Carvalho, M. J.; Amorim, Ricardo; Mendes, J. Farinha; Lopes, Vitor V.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Dynamic testing of solar thermal systems is presently defined by ISO 9459-5:2007. The testing methodology is clearly defined in the standard. Presently, laboratories that use Dynamic System Testing methodology only have available for identification of parameters, a closed source program, which is based on a model described by Spirkl and Muschawek (1992). The present paper describes the work done following a different approach for the identification of parameters – use of TRNSYS to simulate the system and use of GENOPT for optimization. Results are presented, both for thermosyphon and forced circulation systems, and show, in most cases, good agreement (differences lower then ±5%) when compared with the results using ISS, v2.7 (from In Situ Scientific Software). Comparison of system energy yield, calculated using TRNSYS for periods higher than one month, with measured energy yield for these periods, was also done for a thermosyphon system showing very good agreement (differences lower than ±3%).

‣ Esquemas de pintura para estruturas marítimas

Diamantino, Teresa C.; Alves, Isabel Nascimento; Gonçalves, Rita; Marques, Maria João F.; Costa, M. Rosário
Fonte: LNEG – Laboratório Nacional de Energia e Geologia, I.P. Publicador: LNEG – Laboratório Nacional de Energia e Geologia, I.P.
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Nas últimas décadas tem-se verificado um grande aumento das aplicações das ligas de alumínio nas estruturas marítimas. Os danos estruturais que se têm verificado em embarcações devem-se, em grande parte, a problemas de corrosão. Assim, as ligas de alumínio têm que ter uma protecção anticorrosiva adequada. As estruturas marítimas, nomeadamente os cascos dos navios devem ser mantidos preferencialmente livres de organismos por forma a minimizar a resistência ao atrito e consequentemente o consumo de combustível. Para tal são aplicados revestimentos anti-incrustantes para evitar a fixação destes organismos. Nos últimos anos têm-se verificado grandes desenvolvimentos de investigação, desenvolvimento e inovação (IDI) para obtenção de tintas anti-incrustantes (AI) com uma melhor eficiência anti-incrustante em total concordância com a legislação ambiental. O principal objetivo deste estudo reside na avaliação da proteção anticorrosiva e da eficiência anti-incrustante de 3 diferentes esquemas de pintura envolvendo tintas AI com diferentes biocidas. Estas avaliações envolveram ensaios de envelhecimento artificial (resistência ao nevoeiro salino, à imersão em água do mar sintética e à delaminação catódica) e de exposição natural durante dois anos. Estes esquemas de pintura foram caracterizados visualmente...

‣ Corrosão e protecção em estruturas offshore: projecto WIND_ENERMAR

Marques, Maria João F.; Alves, Isabel Nascimento; Gonçalves, Rita; Diamantino, Teresa C.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2014 Português

‣ Prídolí graptolites in the Amêndoa-Carvoeiro Synform (SW border of the Central Iberian Zone, Portugal) : biostratigraphical relevance

Piçarra, José Manuel; Romão, José Manuel
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /07/2011 Português

‣ A Falha de Pinhal Novo-Alcochete no contexto da neotectónica do Vale Inferior do Tejo

Moniz, Catarina; Cabral, João; Madeira, J.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em /07/2011 Português

‣ Pressure cooker under pressure: implementation of life cycle strategies and tools in a medium sized industry in Portugal

Rocha, Cristina; Alexandre, Jorge; Camocho, David; Martins, Paulo
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2014 Português
This paper concerns the application of a set of life cycle oriented strategies and tools to a pressure cooker manufactured by a medium size company located in Portugal and targeting the international market. The life cycle assessment (LCA) indicated the major environmental problems of this product, which together with the company strategy of appealing the consumer through a 100% recyclable and more ergonomic product, provided the direction for the product and market development. Besides the LCA, an ecodesign project was carried out for a reference pressure cooker and through the use of several tools, including ecodesign checklists co-developed by LNEG in a previous project, a number of improvement options was generated, leading to the reduction and substitution of raw materials consumption, improved recyclability, better ergonomic features, more eco-friendly packaging and improved user interaction. A simplified environmental product declaration for the reference product was elaborated, in the framework of the EU Stepwise EPD project, and its marketing asset was evaluated through different communication methods, including phone meetings, website feedback, mailing lists and direct communication with customers in business fairs. This paper presents the results of this project and the characteristics of the improved product...