Faculdade de Ciências e Tecnologia
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Browsing Faculdade de Ciências e Tecnologia by contributor "Afonso, P. M."
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- Composition and in vitro antioxidants activity of Chamaerops Humilis L.Publication . Coelho, Jose P.; Veiga, Jerson G.; Elvas-Leitao, Ruben; Brigas, Amadeu; Dias, Ana M.; Oliveira, Maria C.; Morgado, M.; Bernardes, R.; Amador, M.; Afonso, P. M.The aim of this work is to evaluate the polyphenols composition and the antioxidant activity of methanol extracts of Chamaerops humilis L. Methanol extracts from dried leaves of Chamaerops humilis were prepared using Soxhlet extraction and examined as potential sources of phenolic compounds. Different methods were used to evaluate antioxidant activity of the extracts, including colored (ABTS*+), DPPH radical scavenging assay and reducing power. Total phenolic and flavonoid contents of the extracts were evaluated by Folin-Ciocalteu and aluminum chloride (AlCl3) methods, respectively. Phenolic compositions of the methanol extracts were elucidated by high performance liquid chromatography coupled on-line with tandem mass spectrometry (HPLC-MS/MS). The extract was mainly composed of C-and O-flavones and its O-methylated derivatives. The results suggest that methanol extracts have good potential as sources of bioactive compounds and presents an important antioxidants capacity, which can ensures its potential recommendation for application in the pharmaceutical and nutraceutical sectors.
- Validation of a similarity measurement method for clustering cardiac signalsPublication . Kianimajd, A.; Graca Ruano, Maria; Carvalho, P.; Henriques, J.; Rocha, T.; Paredes, S.; Morgado, M.; Bernardes, R.; Amador, M.; Afonso, P. M.Development of personalized cardiovascular management systems involves automatic identification of the current data as normal or pathological; considering cardiac data as time-series, the illness identification may be performed by seeking similarity between the current patient's time-series data and a reference signal and then proceeding to illness stratification (clustering). Seven of the most common methods of time-series similarity measurement were assessed by imposing 6 types of distortions to the reference signal, considering for each distortion 20 possible variations. This study employed 10 seconds length records of arterial blood pressure signals of healthy subjects, collected from a public database. Then clustering using Partitioning Around Medoids was performed among pathological and non-pathological data considering 3 different clusters. Clustering results confirm usage of the reduced basis Discrete Wavelet Transform resulting from the combination of Haar wavelet decomposition with the Karhunen-Loeve transforms, presenting an accuracy ranging from 76% to 85% when partitioning around Medoids clustering is used.