dAMUSE : a new tool for denoising and blind source separation

In this work a generalized version of AMUSE, called dAMUSE is proposed. The main modification consists in embedding the observed mixed signals in a high-dimensional feature space of delayed coordinates. With the embedded signals a matrix pencil is formed and its generalized eigendecomposition is computed similar to the algorithm AMUSE. We show that in this case the uncorrelated output signals are filtered versions of the unknown source signals. Further, denoising the data can be achieved conveniently in parallel with the signal separation. Numerical simulations using artificially mixed signals are presented to show the performance of the method. Further results of a heart rate variability (HRV) study are discussed showing that the output signals are related with LF (low frequency) and HF (high frequency) fluctuations. Finally, an application to separate artifacts from 2D NOESY NMR spectra and to denoise the reconstructed artefact-free spectra is presented also.info:eu-repo/semantics/publishedVersio

Structural, morphological and dielectric properties of ErNbO4 prepared by the sol-gel method

In this work, ErNbO4 samples were prepared using the sol-gel method, through the citrate route, and heat-treated at temperatures between 700 and 1600 °C. The structure was studied by X-ray diffraction and Raman spectroscopy. The crystallite size was estimated using the Rietveld refinement and the Sherrer's formula, presenting values from 31.27 to 86.65 nm and from 40.96 to 78.23 nm, respectively. The morphology was studied by scanning electron microscopy. The measurement of the complex permittivity was made using the small perturbation technique, with a cavity operating in TE105 mode, at resonant frequency of 2.7 GHz. The increase of the treatment temperature promoted the increase of the dielectric constant and the dielectric losses were still maintained with low values, allowing their potential application in electric storage devices. The dielectric constant of ErNbO4 in a zero porosity sample case was estimated and compared with the experimental values.publishe

High-pressure Raman study of L-alanine crystal

Pressure-dependent Raman scattering studies in the range 0.0 -- 32 kbar were carried out in L-alanine in order to investigate its external mode phonon spectra in relation to the phase transitions in the crystal. A careful analysis of the spectra shows that the low-energy Raman modes exhibit variation both in frequency and in intensity and between 26 and 28 kbar it is observed a splitting of a external mode, indicating that the D_2 normal phase undergoes a transition. Pressure coefficients for external modes are also given.Comment: 11 pages, Latex, 2 figure

Ionic liquids as entrainers for terpenes fractionation and other relevant separation problems

This work discusses the potential of two phosphonium-based ionic liquids (ILs), [P6,6,6,14]Cl and [P6,6,6,14][(C8H17)2PO2], and one methylimidazolium-based IL, [C4mim][OAc], as entrainers in the fractionation of terpene mixtures, in the desulfurization and denitrification of fuel oils, and in the separation of aromatics from aliphatic hydrocarbons. To this aim, the activity coefficients at infinite dilution of 45 solutes were obtained by gas-chromatography in the temperature range (333.15–458.15) K. Selectivities and capacities were calculated showing that [P6,6,6,14]Cl is adequate for the fractionation of (−)-menthone/L-(−)-menthol mixture, being also a suitable option for the deterpenation of citrus essential oil, and the removal of thiophene and pyridine from aliphatic hydrocarbons. To complement the experimental measurements COSMO-RS model was tested, demonstrating good potential to screen separation agents and give insights for several important separation problems, including the removal of contaminants from fuels and the isolation, fractionation and purification of terpenes mixtures.This work was developed within the scope of the project CICECOAveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, and CIMO-Mountain Research Center, UIDB/00690/2020, both financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. Sérgio M. Vilas-Boas also thanks FCT for the Ph.D. grant (SFRH/BD/138149/2018).info:eu-repo/semantics/publishedVersio

Characterization of mutant met100lys of cytochrome c-550 from thibacillus-versutus with Lysine-histidine heme ligation

Macromolecular Biochemistr

Quantification of endogenous auxin levels and polyphenoloxidase enzymatic activity in olive (Olea europaea L.)

A actividade enzimática de polifenoloxidases foi avaliada em folhas e na zona apical, média e basal de ramos de duas cultivares de oliveira (Olea europaea L.), comuns no Alentejo ( Galega vulgar e Cobrançosa ), mostrando que a actividade enzimática nas folhas foi muito superior à encontrada em tecidos de ramos do ano. Maior actividade enzimática foi também detectada na variedade Cobrançosa versus Galega vulgar . As condições óptimas para a determinação da actividade enzimática foram: pH= 5.5 e T= 40 ºC, com 20 mM de 4-metilcatecol em tampão acetato. Nestas condições o KM determinado foi: 2,60 e 3,48 mM com o método de Michaelis-Menten e Lineweaver-Burk, respectivamente. A melhor recuperação das auxinas AIA (ácido indol-3-acético) e AIB (ácido indolbutírico) em material vegetal foi conseguida através da extracção das amostras com acetona. A separação, identificação e quantificação do AIA e AIB em padrões, material vegetal dopado (tecidos de oliveira dopados com uma concentração conhecida de padrão) e não dopado, foi efectuada por técnicas cromatográficas (HPLC-DAD e LCMS), mostrando os resultados taxas de recuperação superiores a 40% para o AIA e 60% para o AIB

Tuning the bioactivity of tensioactive deoxy glycosides to structure: antibacterial activity versus selective cholinesterase inhibition rationalized by molecular docking

New octyl/dodecyl 2,6-dideoxy-D-arabino-hexopyranosides have been synthesized by a simple but efficient methodology based on the reaction of glycals with alcohols catalysed by triphenylphosphane hydrobromide, deprotection, regioselective tosylation and reduction. Their surface-active properties were evaluated in terms of adsorption and aggregation parameters and compared with those of 2-deoxy-D-glycosides and 2,6-dideoxy-L-glycosides. Deoxygenation at the 6-position led to a decrease in the critical micelle concentration, and an increase in the adsorption efficiency (pC20) promoting aggregation more efficiently than adsorption. With regard to the antibacterial activity, dodecyl 2,6-dideoxy-α-L-arabino-hexopyranoside was the most active compound towards Bacillus anthracis (MIC 25 μM), whereas its enantiomer exhibited a MIC value of 50 μM. Both 2,6-dideoxy glycosides were active towards Bacillus cereus, Bacillus subtilis, Enterococcus faecalis and Listeria monocytogenes. In contrast, none of the 2-deoxy glycosides was significantly active. These results and the data on surface activity suggest that aggregation is a key issue for antimicrobial activity. Beyond infection, Alzheimer’s disease also threatens elderly populations. In the search for butyrylcholinesterase (BChE) selective inhibition, 2- deoxy glycosides were screened in vitro by using Ellman’s assay. Octyl 2-deoxy-α-D-glycoside was found to be a BChE selective inhibitor promoting competitive inhibition. Docking studies supported these results as they pinpoint the importance of the primary OH group in stabilizing the BChE inhibitor complex. A size-exclusion mechanism for inhibition has been proposed based on the fact that acetylcholinesterase (AChE) exhibits several bulky residues that hinder access to the active-site cavity. This work shows how the deoxygenation pattern, configuration and functionality of the anomeric centre can tune physical and surface properties as well as the bioactivity of these multifunctional and stereochemically rich molecules.FEDER e FCTinfo:eu-repo/semantics/publishedVersio

Desenvolvimento de uma versão portuguesa do nutritional risk screening NRS 2002

O Nutritional Risk Screening (NRS 2002) é um instrumento que foi desenvolvido pela Danish Society for Parenteral and Enteral Nutrition. Trata-se de um sistema válido que permite detetar a presença do risco de desnutrição ou de desnutrição em indivíduos hospitalizados e que é aplicado pelos profissionais de saúde. Procedeu-se ao desenvolvimento de uma versão para a língua Portuguesa do NRS 2002 com equivalência linguística e cultural ao original, recorrendo à metodologia proposta pela Organização Mundial da Saúde "Processo de tradução e de adaptação de instrumentos". Realizou-se uma tradução avançada e a retrotradução, através das seguintes etapas: tradução (1.ª etapa), retrotradução efetuada por um ou mais especialistas (2.ª etapa), pré-teste (3.ª etapa) e preparação da versão final (4.ª etapa). Este artigo tem como objetivo divulgar este processo e também a versão Portuguesa do NRS 2002.The Nutritional Risk Screening (NRS 2002) is a tool that was developed by the Danish Society for Parenteral and Enteral Nutrition. It is a valid system that allows the detection of the risk of undernutrition or of undernutrition in hospitalized individuals and is applied by health professionals. A Portuguese language version of NRS 2002 was developed with linguistic and cultural equivalence to the original using the WHO proposed methodology "Process of translation and adaptation of instruments". Advanced translation and back-translation were carried out through the following steps: translation (1st stage), back-translation performed by one or more specialists (2nd stage), pre test (3rd stage) and preparation of the final version (4th stage). This article aims to describe this process and also the Portuguese version of NRS 2002