How Climatic Seasons of the Amazon Biome Affect the Aromatic and Bioactive Profiles of Fermented and Dried Cocoa Beans?

In addition to the vast diversity of fauna and flora, the Brazilian Amazon has different climatic periods characterized by periods with greater and lesser rainfall. The main objective of this research was to verify the influence of climatic seasons in the Brazilian Amazon (northeast of Pará state) concerning the aromatic and bioactive profiles of fermented and dried cocoa seeds. About 200 kg of seeds was fermented using specific protocols of local producers. Physicochemical analyzes (total titratable acidity, pH, total phenolic compounds, quantification of monomeric phenolics and methylxanthines) and volatile compounds by GC-MS were carried out. We observed that: in the summer, the highest levels of aldehydes were identified, such as benzaldehyde (6.34%) and phenylacetaldehyde (36.73%), related to the fermented cocoa and honey aromas, respectively; and a total of 27.89% of this same class was identified during winter. There were significant differences (p ≤ 0.05, Tukey test) in the profile of bioactive compounds (catechin, epicatechin, caffeine, and theobromine), being higher in fermented almonds in winter. This study indicates that the climatic seasons in the Amazon affect the aromatic and bioactive profiles and could produce a new identity standard (summer and winter Amazon) for the cocoa almonds and their products.     

Design of new highly luminescent Tb complexes using theoretical combinatorial chemistry

The relation between the structure and luminescent properties of Tb³⁺ complexes containing β-diketonate ligands has been investigated by means of theoretical combinatorial chemistry. The new hybrid method developed combines an empirical relation involving the energy of the lowest triplet state of Tb³⁺ complexes with extremely fast semiempirical quantum mechanical calculations. The concomitant use of phenyl groups attached at both extremities of the β-diketonate ligand has shown to give rise to complexes exhibiting theoretical emission quantum yields higher than 0.5. The results indicate that the proposed method may be used as a valuable tool for predicting luminescent properties of a large number of Tb³⁺ complexes in a relatively short computational time, therefore contributing to further developments in the field of theoretical combinatorial chemistry.     

Mechanistic Insights into Statistical Co-Assembly of Metal Complexes

Statistical copolymerization plays a key role in many biological and technological processes; however, mechanistic understanding of the formation of analogous supramolecular counterparts remains limited. Herein, we report detailed insights into the supramolecular co-assembly of two π-conjugated Pd^II and Pt^II complexes, which in isolation self-assemble into flexible fibers and nanodisks, respectively. An efficient single-step co-assembly into only one type of nanostructure (fibers or nanodisks) takes place if any of the components is in excess. In contrast, equimolar mixtures lead to Pd^II-rich fiber-like co-assemblies by a statistical co-nucleation event along with a residual amount of self-sorted nanodisks in a stepwise manner.     

Stress relaxation in crumpled surfaces

The stress relaxation in crumpled surfaces maintained at a fixed compressive strain is investigated. The experiments indicate a slow relaxation of the mechanical stress in these non-equilibrium disordered systems. The experimental data indicate an anomalous stretched exponential decay with exponent β=0.28±0.03 along six decades in the rescaled variable t/τ, for a wide interval of strain. The results are compared with the similar behaviour of glassy materials, among others.     

Antileishmanial activity of the hydroalcoholic extract of Miconia langsdorffii, isolated compounds, and semi-synthetic derivatives

The in vitro activity of the crude hydroalcoholic extract of the aerial parts of Miconia langsdorffii Cogn. was evaluated against the promastigote forms of L. amazonensis, the causative agent of cutaneous leishmaniasis in humans. The bioassay-guided fractionation of this extract led to identification of the triterpenes ursolic acid and oleanolic acid as the major compounds in the fraction that displayed the highest activity. Several ursolic acid semi-synthetic derivatives were prepared, to find out whether more active compounds could be obtained. Among these ursolic acid-derived substances, the C-28 methyl ester derivative exhibited the best antileishmanial activity.     

Critical properties of contact process on the Apollonian network

We investigate an epidemic spreading process by means of a computational simulation on the Apollonian network, which is simultaneously small-world, scale-free, Euclidean, space-filling and matching graphs. An analysis of the critical behavior of the Contact Process (CP) is presented using a Monte Carlo method. Our model shows a competition between healthy and infected individuals in a given biological or technological system, leading to a continuous phase transition between the active and inactive states, whose critical exponents β/_ν⊥$\beta /{\nu }_{\perp }$ and 1/_ν⊥$1/{\nu }_{\perp }$ are calculated. Employing a finite-size scaling analysis, we show that the continuous phase transition belongs to the mean-field directed percolation universality class in regular lattices.     

Ultra-high pressure LC determination of glucosamine in shrimp by-products and migration tests of chitosan films

Chitosan, a multiple applications molecule, was isolated from shrimp by-products by fermentation. The amount of chitosan in the solid fraction of the fermented extract was measured after its conversion in the respective glucosamine units. The procedure includes an acid hydrolysis (110 °C, 4 h with HCl 8 M) and a derivatization with 9-fluorenylmethyl chloroformate (Fmoc-Cl). Ultra-high-pressure liquid chromatography method was developed and optimized. Excellent peaks resolution was achieved in just 10 min. The method was evaluated in what concerns to validation parameters such as linearity, repeatability, quantification limit, and recovery. Migration tests of films prepared with chitosan were carried out in two simulants: ultrapure water and ethanol 95% (v/v).