Publications

Abstract The polycondensation of silicic acid, methylsilicic acid, or their mixture was studied by reactive force field simulation. These were found to be feasible systems for the simulation of two-step acid hydrolysis-alkaline condensation of their alkoxysilane counterparts, usually taken experimentally as sol-gel precursors. The approach avoided the alkoxysilane hydrolysis step and allowed high degrees of polycondensation at relatively low temperature (700-1000 K), from the computational efficiency perspective. Being the ultimate interest of the present study the sol-gel polycondensation of templated gels whose microstructural pattern is affected by the presence of a template, the role of the intermolecular forces was decisive, and promoted high polycondensation at the lowest possible temperature. Polycondensation with added damascenone did not result in any perceived templating effect, i.e., damascenone was not able to interact significantly with the growing clusters, in a way that would allow its occlusion or a surface molding effect on the clusters. A possible reason for this is the intermolecular interaction strength being too weak at the temperatures set for the simulations. However, when using luteolin as the template, a molecule with several hydrogen bond interaction points, it was possible to observe different microscopic events involving the template molecules, some of them corresponding to actual templating effects, such as partial enveloping by the network around the template. These restricted events did not allow the inference of any macroscopic property of the final gel. However, it was shown that polycondensates shaped by the template or a template dimer may be obtained. The sites thus obtained will be essential for future in silico studies of the selectivity of such sites.

Abstract In this work we report a new potential model for classical molecular dynamics (MD) simulation of two dipolar aprotic solvents - propylene carbonate (PC) and gamma-butyrolactone (GBL). Parameters for intramolecular interactions as well as the partial atomic charges were derived from quantum chemical calculations, while the OPLS/AA force field Lennard-jones intermolecular parameters were adjusted to reproduce the experimental thermodynamic and the transport properties of these solvents in the wide temperature range. The comparison of new potential models with existing models for PC and GBL is given. Using the proposed models, the local structure of these solvents was studied in detail, paying special attention to packing ability, dipole-dipole orientation and hydrogen-bonding (H-bonding) interactions. Based on the results of MD simulations and QTAIM analysis, it was shown that H-bonds involving carbonyl oxygen atoms in PC and GBL are rather weak, while no H-bonds are formed with ester oxygen atoms. According to the present results, the mutual molecular orientation in PC and GBL varies with the distance, being above/below plane-parallel configuration for closest neighbors, and in-plane T-shaped configurations for farther neighbors. The nearest neighbors approach coupled with angular distribution functions was applied for the estimation of the Kirkwood factor in the framework of the OnsagerKirkwood-Frohlich theory. Our results shows that in order to reproduce the corresponding experimental values the Kirkwood factor it is necessary to take in account the mutual orientation of similar to 8-9 neighboring molecules for GBL and similar to 5-6 molecules for PC. (C) 2019 Published by Elsevier B.V.

Abstract Concerns for the environment and sustainability are a priority to modern societies and one of the reasons for the emergence of movements against mining exploration. To avoid the opposition of local populations to mining activity, especially open-pit mining, there is a need to proceed with both best practices and technical knowledge that involve the local population and also carry out systematic environmental monitoring. The aim of this study is to evaluate the potential environmental impacts of C57 lithium mine exploration in the village of Goncalo, district of Guarda, Portugal, on water, soil and atmospheric air quality. Determining the concentration of cations, anions, pH and conductivity for water and soil quality evaluation was performed by atomic absorption spectroscopy, ion chromatography and potentiometric methods. For the evaluation of atmospheric air quality, beta radiation absorption, chemiluminescence, UV absorption photometric and infrared radiation methods were used. The results lead to the conclusion that there is no evidence of soil and water quality degradation due to mine exploration. However, there is a perception of the existence of environmental impact on air quality, especially on nitrogen dioxide and particulate matter (PM1, PM2.5 and PM10), although the emissions of air pollutants are below the limits established by Portuguese legislation.

Abstract Modern societies are great producers of waste because of their energy and natural resource needs. Many of these wastes are disposed of in landfills, which require a significantly sized area of soil and special geotechnical conditions. The reaction between alumina-silicate and an aqueous alkali hydroxide and silicate solution produces an alkali-activated cement (AAC). The use of AAC, an inorganic material with a chemical structure of polymeric Si-O-Al bonds, can promote the stabilisation and immobilisation of a wide variety of waste sources containing hazardous materials. The purpose of this study is to evaluate the effect of curing conditions on the resistance and permeability and in the quality of the seepage water generated over time in transport infrastructure platforms built with soil stabilised with AAC. The strength results show that the material meets the requirements for use in building low-cost roads. Permeability tests of AAC samples show a relatively low permeability (between 10(-8) and 10(-7) m/s), a positive factor for environmental and geotechnical considerations. However, this permeability still results in significant leachate water with quality and contaminant issues, particularly in chromium (Cr), cadmium (Cd), aluminium (Al), sodium and silicon (Si), and high pH.

Abstract Exogenous antioxidants may be beneficial therapeutic tools to tackle the oxidative damage in neurodegenerative diseases by regulation of the redox state that is critical for cell viability and organ function. Inspired by natural plant polyphenols, a series of cinnamic acid-based thiophenolic and phenolic compounds were synthesized and their antioxidant and neuroprotective properties were studied. In general, our results showed that the replacement of the hydroxyl group (OH) by a sulfhydryl group (SH) increased the radical scavenging activity and enhanced the reaction rate with 1,1-diphenyl-2-picrylhydrazyl radical (DPPH center dot) and galvinoxyl radical (GO(center dot)). These results correlated well with the lower oxidation potential (E-p) values of thiophenols. However, a lower peroxyl radical (ROO center dot) scavenging activity was observed for thiophenols in oxygen radical absorbance capacity (ORAC-FL) assay. Furthermore, the introduction of 5-methoxy and 5-phenyl groups in the aromatic ring of 4-thioferulic acid (TFA) 2 and ferulic acid (FA) 1 did not significantly improve their antioxidant activity, despite the slight decrease of E-p observed for compounds 5, 6, and 9. Concerning cinnamic acid amides, the antioxidant profile was similar to the parent compounds. None of the compounds under study presented significant cytotoxic effects in human differentiated neuroblastoma cells. Thiophenolic amide 3 stands out as the most promising thiophenol-based antioxidant, showing cellular neuroprotective effects against oxidative stress inducers (hydrogen peroxide and iron).

Abstract Purpose: The positional analysis of hepatic glycogen enrichment from deuterated water ((H2O)-H-2) by H-2 NMR has been applied previously to resolve the contributions of glucose and fructose to glycogen synthesis in rodents fed a high sucrose diet. To further validate this method, this analysis was applied to mice fed with synthetic diets whose carbohydrate components consisted solely of either glucose or fructose. Methods: Eight glucose-fed and 12 fructose-fed mice were given (H2O)-H-2 followed by ad libitum feeding overnight. Mice were then euthanized, hepatic glycogen was isolated and derivatized to monoacetone glucose, and H-2-enrichment of positions 2, 5, and 6(S) were measured by H-2 NMR. From these data, the fraction of overnight glycogen appearance from the direct pathway and/or glycogen cycling and indirect pathway were estimated. Indirect pathway fractions were resolved into Krebs cycle and triosephosphate sources-the latter including contributions from fructose metabolism. Results: After overnight feeding, the fraction of overnight glycogen appearance derived from direct pathway and/or glycogen cycling in glucose-fed-mice was 63 +/- 1%. For the indirect pathway, Krebs cycle and triose-phosphate sources contributed 22 +/- 1% and 15 +/- 1%, respectively. For fructose-fed-mice, glycogen appearance was dominated by triose-phosphate sources (60 +/- 2%) with lesser contributions from Krebs cycle (14 +/- 1%) and direct and/or glycogen cycling (26 +/- 2%). Conclusions: H-2 NMR analysis of hepatic glycogen H-2 enrichment from (H2O)-H-2 provides realistic profiles of dietary glucose and fructose contributions to hepatic glycogen synthesis in mice fed with diets containing 1 or the other sugar as the sole carbohydrate source.

Abstract Deuterated water (2H2O) is widely used for measuring de novo lipogenesis (DNL). 2H is incorporated into fatty acids via exchange between body water and the hydrogens of acetyl-CoA, malonyl-CoA, and NADPH. Previous studies concluded that these exchanges are incomplete; therefore, fatty acid 2H enrichment requires correcting. In mice, we measured the 2H enrichment of fatty acid positions 2 and 3 and methyl hydrogens from [U-2H7]glucose to determine 2H transfer from glucose to fatty acid via malonyl-CoA, NADPH, and acetyl-CoA, respectively. Positional fatty acid 2H enrichments were compared with 13C enrichment of the same sites from an equivalent amount of [U-13C6]glucose provided alongside the [U-2H7]glucose tracer. Transfer of glucose 2H to fatty acid position 2 and methyl sites was low (2H enrichment of 0.06 ± 0.01 and 0.14 ± 0.01 relative to 13C) indicating extensive exchange at both malonyl- and acetyl-CoA, respectively. Transfer of glucose 2H into fatty acid position 3 was more extensive (0.46 ± 0.04 relative to 13C, P < 10-5 vs. position 2), indicating a more limited exchange of those glucose hydrogens that were transferred via NADPH. However, mice provided with [U-13C6]glucose and 2H2O had equivalent 2H enrichments of fatty acid positions 2 and 3, suggesting that in this setting, NADPH and body water 2H had exchanged extensively. This is explained by contributions of substrates other than exogenous glucose to DNL coupled with their extensive 2H enrichment from 2H2O prior to DNL. Under such conditions, 2H enrichment of fatty acids from 2H2O does not need correction. Copyright © 2019 Belew et al.

Abstract Considering the high incidence level and mortality rate of ovarian cancer, particularly among the European female population, the carbohydrate antigen 125 (CA-125) was selected as the protein target for this study for the development of a MIP-based biosensor. This work presents the development of molecular imprinting polymers (MIPs) on gold electrode surface for CA-125 biomarker recognition. The preparation of the CA-125 imprinting was obtained by electropolymerization of pyrrole (Py) monomer in a gold electrode using cyclic voltammetry (CV) in order to obtain highly selective materials with great molecular recognition capability. The quantification of CA-125 biomarker was made through the comparison of two methods: electrochemical (square wave voltammetry -SWV) and optical transduction (surface plasmon resonance -SPR). SWV has been widely used in biological molecules analysis since it is a fast and sensitive technique. In turn, SPR is a non-destructive optical technique that provides high-quality analytical data of CA-125 biomarker interactions with MIP. Several analytical parameters, such as sensitivity, linear response interval, and detection limit were determined to proceed to the performance evaluation of the electrochemical and optical transduction used in the development of the CA-125 biosensor. The biosensor based in the electrochemical transduction was the one that presented the best analytical parameters, yielding a good selectivity and a detection limit (LOD) of 0.01 U/mL, providing a linear concentration range between 0.01 and 500 U/mL. This electrochemical biosensor was selected for the study and it was successfully applied in the CA-125 analysis in artificial serum samples with recovery rates ranging from 91 to 105% with an average relative error of 5.8%.