Biosystems & Integrative Sciences Institute

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Ultrasound and radiation-induced catalytic oxidation of 1-phenylethanol to acetophenone with iron-containing particulate catalysts

Publication . Soliman, Mohamed Mostafa Aboelhassan; Kopylovich, Maximilian N.; Alegria, Elisabete; Da Costa Ribeiro, Ana Paula; Ferraria, Ana Maria; Rego, Ana; Correia, Luís M. M.; Saraiva, Marta S.; Pombeiro, Armando

Iron-containingparticulatecatalystsof0.1–1 µmsizewerepreparedbywetandball-milling procedures from common salts and characterized by FTIR, TGA, UV-Vis, PXRD, FEG-SEM, and XPS analyses. It was found that when the wet method was used, semi-spherical magnetic nanoparticles were formed, whereas the mechanochemical method resulted in the formation of nonmagnetic microscale needles and rectangles. Catalytic activity of the prepared materials in the oxidation of 1-phenylethanol to acetophenone was assessed under conventional heating, microwave (MW) irradiation, ultrasound (US), and oscillating magnetic ﬁeld of high frequency (induction heating). In general, the catalysts obtained by wet methods exhibit lower activities, whereas the materials prepared by ball milling aﬀord better acetophenone yields (up to 83%). A signiﬁcant increase in yield (up to 4 times) was observed under the induction heating if compared to conventional heating. The study demonstrated that MW, US irradiations, and induction heating may have great potential as alternative ways to activate the catalytic system for alcohol oxidation. The possibility of the synthesized material to be magnetically recoverable has been also veriﬁed.

2020-02-01Journal article

Open access

Molecular-level changes induced by hydroxycinnamic acid derivatives in HepG2 cell line: comparison with pravastatin

Publication . RESSAISSI, Asma; Pacheco, Rita; Serralheiro, Maria Luisa

Hydroxycinnamic acid derivatives are an important class of polyphenols found in fruits, vegetables, and medicinal plants and widely consumed in human diet. In the present work, alterations of HepG2 cells biochemical profile under the effect of four hydroxycinnamic acid derivatives (caffeic acid, m-coumaric acid, chlorogenic acid and rosmarinic acid) relatively to the effect of pravastatin, a drug often prescribed to inhibit HMG-CoA reductase enzyme, the regulator enzyme in the cholesterol biosynthesis pathway, were reported. The application of FTIR spectroscopy in combination with multivariate analysis by PCA showed a similarity between pravastatin and the four hydroxycinnamic acid derivatives in metabolite profile modification expressed by various changes in proteins region, the phosphate region which mainly corresponds to nucleic acids as well as in lipids regions. FTIR structural analysis in the amide I region, using resolution enhancement methods, such as second derivative and amide I deconvolution method, revealed significant decrease in alpha-helix/random coil and intermolecular beta-sheet decreased while intramolecular beta-sheet in treated cells showed an increase. It was also noticed that the intracellular cholesterol as well as esterified ingredients such as cholesterol esters in the cell membrane decreased. Moreover, principal component analysis (PCA) of the spectral data showed that the compounds and pravastatin were well separated from untreated cells showing a different mode of action on HepG2 treated cells for each compound.

2021-10-15Journal article

Restricted access

On lattices from combinatorial game theory: infinite case

Publication . Carvalho, Alda; Santos, Carlos; Dias, Cátia; Coelho, Francisco; Neto, João P.; Nowakowski, Richard; Vinagre, Sandra

Given a set of combinatorial games, the children are all those games that can be generated using as options the games of the original set. It is known that the partial order of the children of all games whose birthday is less than a fxed ordinal is a distributive lattice and also that the children of any set of games form a complete lat tice. We are interested in the converse. In a previous paper, we showed that for any fnite lattice there exists a fnite set of games such that the partial order of the chil dren, minus the top and bottom elements, is isomorphic to the original lattice. Here, the main part of the paper is to extend the result to infnite complete lattices. An original motivating question was to characterize those sets whose children generate distributive lattices. While we do not solve it, we show that if the process of taking children is iterated, eventually the corresponding lattice is distributive.

2020-03-12Journal article

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Combinatorics of JENGA

Publication . Carvalho, Alda; Neto, João; Santos, Carlos

JENGA, a very popular game of physical skill, when played by perfect players, can be seen as a pure combinatorial ruleset. Taking that into account, it is possible to play with more than one tower; a move is made by choosing one of the towers, removing a block from there, that is, a disjunctive sum. JENGA is an impartial combinatorial ruleset, i.e., Left options and Right options are the same for any position and all its followers. In this paper, we illustrate how to determine the Grundy value of a JENGA tower by showing that it may be seen as a bidimensional vector addition game. Also, we propose a class of impartial rulesets, the clock nim games, JENGA being an example of that class.

2020Journal article

Open access