1,066 research outputs found
Geochemistry of the Baixo Alentejo Flysch Group, South Portuguese Zone: implications for provenance and palaeoweathering
The Baixo Alentejo Flysch Group (BAFG) is one of the
domains of the South Portuguese Zone, consisting of deepwater tubiditic sediments, with more than 5 km in thickness.
Stratigraphically the BAFG is subdivided into three
formations, from the bottom to the top: Mértola Formation,
Mira Formation and Brejeira Formation, with ages ranging
from Middle to Upper Carboniferous
Caracterização geoquímica do Grupo do Flysch do Baixo Alentejo (Zona Sul Portuguesa): resultados preliminares
O Grupo do Flysch do Baixo Alentejo (GFBA) é um dos domínios da Zona Sul Portuguesa
(ZSP), sendo constituído por sedimentos turbidíticos profundos, com uma espessura superior a 5 km
(Oliveira, 1990)
Bioproducts from seaweeds: a review with special focus on the Iberian Peninsula
Seaweeds, i.e. macroalgae that occupy the littoral zone, are a great source of compounds with diverse applications; their types and content greatly determine the potential applications and commercial values. Algal polysaccharides, namely the hydrocolloids: agar, alginate and carrageenan, as well as other non-jellifying polysaccharides and oligosaccharides, are valuable bioproducts. Likewise, pigments, proteins, amino acids and phenolic compounds are also important, exploitable compounds. For the longest time the dominant market for macroalgae has been the food industry. More recently, several other industries have increased their interest in algal-derived products, e.g. cosmetics, pharmaceuticals and more recently, as a source of feedstock for biorefinery applications. This manuscript reviews the chemical composition of dominant macroalgae, as well as their potential added-value products and applications. Particular attention is devoted to the macroalgal species from the Iberian Peninsula. This is located in the Southwest of Europe and is influenced by the distinct climates of the Mediterranean Sea and the Atlantic Ocean, representing a rich spot of marine floral biodiversity
Análise de proveniência dos sedimentos siliciclásticos do Grupo do Flysch do Baixo Alentejo, Zona Sul Portuguesa
Os estudos de análise de proveniência dos sedimentos siliciclásticos do Grupo do Flysch do Baixo Alentejo sugerem mudanças na natureza das áreas fonte ao longo da sua história deposicional. Petrograficamente regista-se uma mudança de áreas iniciais caracterizadas por rochas magmáticas para áreas representadas por rochas (meta)sedimentares recicladas. Os indicadores geoquímicos de proveniência sugerem mistura de fontes, envolvendo quer rochas ígneas félsicas, quer litologias máficas para a Fm. Mértola, evoluindo para um predomínio de rochas (meta)félsicas associada à área fonte dos sedimentos siliciclásticas da Fm. Brejeira
Caracterização geoquímica da formação brejeira (grupo do Flysch do Baixo Alentejo): resultados preliminares
A Formação Brejeira é a unidade litoestratigráfica mais recente do Grupo do Flysch do Baixo Alentejo
consistindo, essencialmente, de grauvaques e quartzovaques de natureza turbidítica intercalados com
xistos argilosos. A idade da Fm. Brejeira distribui-se entre o Bashkiriano e o Moscoviano superior
(Carbonífero Superior). O estudo petrográfico e mineralógico dos grauvaques da Fm. Brejeira relevou a
seguinte composição Qt81,6F0,9Lt17,5, resultados que sugerem uma proveniência dos sedimentos de áreas
caracterizadas predominantemente por rochas (meta)sedimentares recicladas.
Do ponto de vista geoquímico os grauvaques são enriquecidos em SiO2 (>75%) reflectindo uma
mineralogia dominada pelo quartzo. Os xistos argilosos apresentam Índices de Variabilidade Composicional
(IVC) inferiores a 1 e baixas razões K2O/Al2O3 (0,2±0,02) e Na2O/K2O (0,15±0,06). As litologias da Fm.
Brejeira exibem padrões normalizados das Terras Raras caracterizados por enriquecimento em Terras
Raras Leves, anomalia de Eu negativa e reduzido fraccionamento das Terras Raras Pesadas. Quer os
grauvaques quer os xistos argilosos possuem valores similares das razões Lan/Smn, Gdn/Ybn e Eu/Eu*. O
Índice de Meteorização Química (CIW) das litologias da Fm. Brejeira é elevado (>80,93) e o Índice de
Alteração da Plagioclase (PIA) apesar de mais variável, é na maioria das amostras elevado (PIA 67,24 –
96,14). Os valores de CIW e PIA sugerem condições de meteorização química de moderada a intensa. Os
dados petrográficos e geoquímicos sugerem áreas-fonte dos sedimentos da Fm. Berjeira caracterizadas
por rochas félsicas e (meta)sedimentares reciclada
Qual a idade mais antiga da Faixa Piritosa? Nova idade Givetiano inferior para o Grupo Filito-Quartzítico (Anticlinal de S. Francisco da Serra, Faixa Piritosa)
A análise palinoestratigráfica de xistos negros do Grupo Filito-Quartzítico, recolhidos na sondagem M-1, na região do Anticlinal de S.
Francisco da Serra, no sector mais a oeste da Faixa Piritosa Ibérica, proporcionou a obtenção de uma associação de mioesporos,
moderadamente preservada, o que permitiu identificar a parte superior da Biozona de Miosporos AD, subzona Lem, de idade
Givetiano inferior (Devónico Médio). Trata-se da idade mais antiga identificada, até ao momento, na Faixa Piritosa Ibérica
New lower Givetian age miospores of the Phyllite-Quartzite Group, São Francisco da Serra Anticline, Iberian Pyrite Belt - Portugal
Palynostratigraphical analysis of Phyllite Quartzite (PQ) Group shales recovered froma drill core and outcrops at the São Francisco da Serra anticline, in the westernmost area of the Iberian Pyrite Belt, yielded a moderately preserved miospore assemblage assigned to the upper part of AD miospore Biozone, subzone Lem, of lower Givetian age. This is the oldest age recognized, up to this date, for any rocks in the Iberian Pyrite Belt
Characterization of silicon photodiodes for diffuse reflectance signal extraction
Early detection of gastrointestinal (GI) can
cers is one
of most important concerns in medical field. Its detection at the
earliest stage is crucial to increase the patient survival chances.
Optical signals extraction and analysis, specifically diffuse
reflectance and intrinsic fluorescence, may impr
ove the ability to
detect GI dysplasia, once some morphological and biochemical
changes on the tissues (related with early cancer progre
ssion) can
modify these signals’
shape and intensity. The project under th
is
paper aims to develop a chip
-
sized spectros
copy microsystem for
the early detection of GI cancer. This paper presents the
characterization of silicon photodiodes (n+/p
-
epilayer type)
fabricated in a standard 0.7 μm CMOS process, with different
dimensions. The main goal is to conclude which photodio
de must
be fabricated for the microsystem implementation, taking into
account its capacity to extract the
signals in the relevant spectral
band (350 nm
–
750 nm), not comprising the microsystem
dimensions. With this study
,
it can be conclude
d
that the suit
able
photodiodes for the detection of those spectroscopic signals are
the
ones with
125 × 125 μm
2
or 100 × 100 μm
2
active area
, once
their quantum efficiency varies between 20% and 55%,
approximately, above 450 nm. In spite of the low photodiod
es
quantum efficiency (lower than 20%) below 450 nm, the viability
of using the 100 × 100 μm
2
photodiode to extract the diffuse
reflectance signal, between 350 nm and 750 nm, was proven using
a test phantom representative
of a GI tissue.This work is funded by FEDER funds through the "Eixo I do Programa Operacional Fatores de Competitividade (POFC) QREN, projects reference COMPETE: FCOMP-01-0124-FEDER-020241 and FCOMP-01-124-FEDER-037291 (PEst-C/FIS/UI0607/2013) and by FCT – Fundação para a Ciência e a Tecnologia, project reference PTDC/EBB-EBI/120334/2010. S. Pimenta thanks the FCT for the SFRH/BD/87605/2012 PhD grant
Metabolic responses to high glycemic index and low glycemic index meals: a controlled crossover clinical trial
BACKGROUND: The consumption of low glycemic index (LGI) foods before exercise results in slower and more stable glycemic increases. Besides maintaining an adequate supply of energy during exercise, this response may favor an increase in fat oxidation in the postprandial period before the exercise compared to high glycemic index (HGI) foods. The majority of the studies that evaluated the effect of foods differing in glycemic index on substrate oxidation during the postprandial period before the exercise are acute studies in which a single meal is consumed right before the exercise. The purpose of this study was to investigate the effect of consuming two daily HGI or LGI meals for five consecutive days on substrate oxidation before the exercise and in the concentrations of glucose, insulin and free fatty acids before and during a high intensity exercise. METHODS: Fifteen male cyclists, aged 24.4 ± 3.8 years, with body mass index of 21.9 ± 1.4 kg.m(-2 )and a V(O2 max )of 70.0 ± 5.3 mL.kg(-1).min(-1), participated in this crossover study. All test meals were consumed in the laboratory. On days 1 and 5, substrate oxidation (30 minutes before and 90 minutes after breakfast (HGI or LGI)) and diet-induced thermogenesis (90 minutes postprandial) were assessed before the exercise. The levels of glucose, insulin, and free fatty acids were determined during 2 h after breakfast on these same days. Ninety minutes after breakfast, subjects completed a 30 min cycloergometric exercise at 85 to 95% of their maximum heart rate, during which lactate concentrations were assessed. RESULTS: The consumption of HGI meals resulted in higher areas under the glycemic and insulinemic curves in the postprandial period. However, glycemia did not differ by study treatment during exercise. There were no differences in free fatty acids in the postprandial period or in lactate levels during exercise. LGI meals resulted in lower fat oxidation and higher carbohydrate oxidation than the HGI meal in the postprandial period. CONCLUSIONS: The results do not support a differential glycemia according to glycemic index during exercise. The ingestion of LGI foods did not lead to higher fat oxidation relative to the ingestion of HGI foods. TRIAL REGISTRATION: ACTRN: ACTRN1260900052221
Design and Development of a Magnus Hydrokinetic Rotor
The energy matrix diversification has become noticed in the latest years. Energy conversion of the free flow in rivers and canals into electrical energy has been a good complementation for the conventional generation. The first application of hydrokinetic turbines, commercially, were in Mississippi's river (Minnesota, USA), in 2008. The USAge of Magnus effect in hydrokinetic turbines occurred in an innovative manner. In this project, rotational cylinders actuate as blades of an axial hydrokinetic rotor, converting kinetic energy of the flow into potency in the rotor axle. This effect was initially observed in 1853 by Henrich Magnus and, since then, few researches were carried out to its application in hydraulic generation of energy. Therefore, tests in reduced-scale prototype and numerical simulations were made for the development and executive design of a hydrokinetic rotor. At the end of this study, a hydro generator with 62% hydraulic efficiency, considering the Betz Limit, was constructed
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