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This work presents the synthesis of 12 phenol and chromone derivatives, prepared by the analogs, and the possibility of conducting an in silico study of its derivatives as a therapeutic alternative to combat the SARS-CoV-2, pathogen responsible for COVID-19 pandemic, using its S-glycoprotein as a macromolecular target. After the initial screening for the ranking of the products, it was chosen which structure presented the best energy bond with the target. As a result, derivative 4 was submitted to a molecular growth study using artificial intelligence, where 8436 initial structures were obtained that passed through the interaction filters and similarity to the active glycoprotein pocket through the MolAICal computational package. Thus, 557 Hits with active configuration were generated, which is very promising compared to the BLA reference link for inhibiting the biological target. Molecular dynamics also simulated these compounds to verify their stability within the active protein site to seek new therapeutic propositions to fight against the pandemic. The Hit 48 and 250 are the most active compounds against SARS-CoV-2. In summary, the results show that the Hit 250 would be more active than the natural compound, which could be further developed for further testing against SARS-CoV-2. The study employs the de novo approach to design new drugs, combining artificial intelligence and molecular dynamics simulations to create efficient molecular structures. This research aims to contribute to the development of effective therapeutic strategies against the pandemic. [ABSTRACT FROM AUTHOR]

Chagas disease (CD) is a tropical disease caused by the parasite Trypanosoma cruzi, transmitted by the barber insect. Currently, there are approximately 7 million infected people in the world, and it is estimated that 70 million people could contract this disease. The anacardic acid (AA) showed effectiveness in in silico and in vitro tests. The antichagasic potential of five sulfonamide molecules, derived from anacardic acid, was evaluated from a molecular approach based on the density functional theory (DFT), molecular dynamics (MD), and molecular docking (docking) calculations. Methyl 2-methoxy-6- (8- (methylsulfonamide) octyl) benzoate (SA1); 2-methoxy-6- (8- (phenylsulfonamide) octyl) benzoate (SA2); methyl 2-methoxy-6- (8- (2methylphenyl sulfonamide) octyl) benzoate (SA3); methyl 2-methoxy-6- (8-(methylphenylsulfonamide)octyl)benzoate (SA4); methyl2-(8-(2,5-dimethylphenylsulfonamide)octyl)-6-methoxybenzoate (SA5) were the investigated molecules. The DFT calculations were performed using the B3LYP/6-311+G (d, p) level of theory. The global and local reactivity data showed that SA1 shows the highest molecular reactivity, while SA2 is the most stable derivative. In addition, the structures of investigated molecules were confirmed by the linear correlations higher than 0.98 displayed between the experimental and calculated spectroscopic data (IR and NMR). Molecular docking of the molecules showed a greater prominence for the SA1, SA2, and SA4 molecules in the results of distances of ligand-cruzain. In molecular dynamics, SA2 obtained better stability due to greater interactions with important amino acids of cruzain. [ABSTRACT FROM AUTHOR]

The methanol crossover effect severely reduces the efficiency of direct methanol fuel cells once it affects the oxygen reduction reaction (ORR) that occurs in the cathode. Hence, methanol dilution has to be carried out to overcome this drawback. However, when methanol is employed as the fuel, its concentration is highly important to improve the performance of these electrochemical devices. Thus, although still very challenging, the rational design of efficient electrocatalysts for such systems via an ORR mechanism is vital. To this end, we reported the synthesis of AgPt nanotubes (1.0 wt% Pt) by a galvanic replacement approach using Ag nanowires as sacrificial templates, which were successfully immobilized on commercial silica. We demonstrated that such hollow AgPt-based material could be employed as a highly selective electrocatalyst, which promoted the system's targeting for the ORR reaction, an essential pathway for renewable energy issues built on fuel cells. Our results were achieved in highly concentrated methanol solutions (up to 7.5 M), which was impossible with the commercial 20 wt% Pt on Vulcan XC-72R (E-TEK). Using theoretical calculations, we showed that Ag atoms were essential to avoid the poisoning as the reactions were less favorable to occur on its surface; then, the random configuration of AgPt nanotubes was crucial for the remarkable selectivity of the system, explaining the high performance of the electrocatalyst due to the synergistic effects between Ag and Pt in the AgPt/SiO2 electrocatalyst. [ABSTRACT FROM AUTHOR]

This work investigated the antioxidant potential of acetylated and nitrated eugenol derivatives through structural analysis and the mechanism of hydrogen atomic transfer (HAT) by density functional theory (DFT). The structures were optimized by the hybrid functional M06-2X with basis set 6–31 + G(d,p), and the HAT mechanism was evaluated with HO, HOO, CH3O, DPPH radicals. In agreement with experimental data from previous studies, two steps of hydrogen transfer were tested. The thermodynamic data showed the need for two hydrogen atomic transfer steps from antioxidants, followed by the formation of p-quinomethanes (27, 28, and 29) to make the reaction spontaneous with DPPH. Furthermore, theoretical kinetic data showed that the preferred antioxidant site depends on the instability of the attacking radical and confirmed the antioxidant profile for eugenol (1, 4-allylbenzene-1,2-diol), and nitro-derivative 7 (5-allyl-3-nitrobenzene-1,2-diol) in the DPPH assay. Finally, this study showed that nitro compound 6 (4-allyl-2-methoxy-6-nitrophenol) also has anti-radical activity with smaller radicals but is not observed in the experiment due to structural characteristics and chemoselectivity of DPPH. [ABSTRACT FROM AUTHOR]

The water influence on electrochemical behaviour of Ag+ ions in urea and choline chloride mixture was investigated by cyclic voltammetry technique, while the molecular insights about the investigated systems were obtained from molecular dynamic (MD) simulation. The water content was variated from 0 up to 10% (v/v). Cyclic voltammetry technique showed that the peak potential for Ag+/Ag redox couples shifted in direction to more positive potentials with the gradual increase of water content in solution, indicating that the addition of water electrocatalyses the kinetics of the reduction of Ag+ ions. The MD simulations demonstrated that water molecules do not interact strongly with Ag+ ions but induce a small reduction in the number of urea molecules around of the ion and that the water molecules adjust to free spaces in the mixture. [ABSTRACT FROM AUTHOR]

A novel platform for carbamate-based pesticide quantification using a chitosan/magnetic iron oxide (Chit-Fe3O4) nanocomposite as a glassy carbon electrode (GCE) modifier is shown for an analytical methodology for determination of bendiocarb (BND). The BND oxidation signal using GCE/Chit-Fe3O4 compared with bare GCE was catalyzed, showing a 37.5% of current increase with the peak potential towards less positive values, showing method’s increased sensitivity and selectivity. Using square-wave voltammetry (SWV), calibration curves for BND determination were obtained (n = 3), and calculated detection and quantification limits values were 2.09 × 10−6 mol L−1 (466.99 ppb) and 6.97 × 10−6 mol L−1 (1555.91 ppb), respectively. The proposed electroanalytical methodology was successfully applied for BND quantification in natural raw waters without any sample pretreatment, proving that the GCE/Chit-Fe3O4 modified electrode showed great potential for BND determination in complex samples.ᅟGraphical abstract [ABSTRACT FROM AUTHOR]

This work describes the electroanalytical determination of Chlorpyriphos pesticide in natural waters using hanging mercury drop electrode allied to square wave adsorptive cathodic stripping voltammetry. The best responses were obtained in Britton‒Robinson buffer solutions at pH 2.0, using a frequency of 100 s-1, a scan increment of 5 mV, a square wave amplitude of 25 mV and an accumulation potential of-0.4 V during 60 s. Therefore, voltammetric responses showed the presence of one well-defined and irreversible reduction peak, at-1.08 V vs. Ag/AgCl/KCl 1.0 M, which involves two electrons in the reduction of carbon‒nitrogen bond in the N-heterocyclic system with the participation of protonation equilibrium preceding the electron transfer reaction. Analytical curves were constructed and compared to similar curves performed by gas chromatograph coupled to a selective nitrogen‒phosphorus detector, which demonstrates that the proposed methodology is suitable for determining contamination by Chlorpyriphos in complex samples. [ABSTRACT FROM AUTHOR]

The pitting corrosion resistance of AL-6XN PLUS™ superaustenitic stainless steel, 304L, 316L, and 317L austenitic stainless steels was investigated using the cyclic polarization technique. These materials were evaluated in the as received condition and heat-treated at temperatures between 500 °C and 900 °C for 72 h. A thermodynamic simulation was performed using the software Thermocalc® to predict possible deleterious phases in selected temperatures. The simulations have predicted the sigma phase in the selected temperature range. An aqueous solution of sulfuric acid and sodium chloride was used as electrolyte in the corrosion tests. The results showed that pitting corrosion was not observed on the samples of AL-6XN PLUS™ steel. The 304L steel suffered pitting corrosion. All the polarization curves of this steel showed hysteresis characteristics of pitting corrosion. The 316L and 317L steels were resistant to pitting corrosion, but susceptible to crevice corrosion. [ABSTRACT FROM PUBLISHER]

Model Fe–9Cr–xMo alloys with high Mo content alloys were cast to investigate the effect of Mo on the phase evolution and properties of the alloys. The Mo contents in the alloys were 5, 7, and 9 wt%, while the Cr content was held constant at 9 wt%. For comparison, a commercial A213T 9-P9 (Fe–9Cr–1Mo) alloy, widely used in the petrochemical industry, was also investigated. The alloys were heat-treated at temperatures between 450 and 650 °C and characterized by scanning electron microscopy, x-ray dispersive energy spectroscopy, and electron backscatter diffraction. Potentiodynamic linear polarization technique was used to evaluate the corrosion of the alloys in a 0.5 mol L−1 H2SO4 solution containing 0.1 mol L−1 NaCl. The results showed that the corrosion resistance of the alloys was affected by precipitation of the µ phase and that the Mo content in excess of 5% is deleterious to the corrosion resistance of the Fe–Cr–Mo alloys. [ABSTRACT FROM PUBLISHER]

This study examined the influence of citrate and tartrate as complexing agents on the electrodeposition and surface morphology of Cu-Ni layers. The alloys obtained in the tartaric acid and sulphate baths were nobler than those obtained in the citric acid/citrate and citric acid/citrate/tartaric acid media. The results indicated that the complexing medium influences the nobility and the type of mass transport of the alloy formed. The morphology of the electrodeposited Cu-Ni layers changed from a rather porous appearance in the absence of the complexing agents to nodular, cracked mud and cauliflower appearances for the citric acid/sodium citrate/sodium sulphate medium, tartaric acid/sodium sulphate medium and citric acid/sodium citrate/tartaric acid/sodium sulphate medium, respectively. The chemical composition of the Cu-Ni layers revealed the preferential deposition of copper. The ultraviolet-visible spectrophotometry measurements indicated the occurrence of the d-d type transition, regardless of the complexing medium employed. [ABSTRACT FROM AUTHOR]

The consequences of aging at 400 and 475 °C on the mechanical properties, corrosion resistance, and magnetic properties of the ferritic stainless steel (SS) AISI 444 were investigated. Age hardening was measured as a function of aging time at both temperatures and was found to be more intense at 475 °C. The localized corrosion susceptibility increased, while the impact toughness decreased with aging time. These two effects were also more important at 475 °C. Unlike duplex SSs, AISI 444 did not present any variation in coercive force or Curie temperature with aging time. The effects on the Mössbauer spectra were also determined and analyzed. [ABSTRACT FROM AUTHOR]

This work describes the investigation of the embrittlement of AISI 304 steel sensitized at 650°C by Charpy impact test, comparing two starting conditions: (1) mill annealed and machined (MA-M); and (2) solution treated at 1050°C by 1 h followed by oil quenching (ST). The degree of sensitization for both samples was assessed by Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and by Double Loop Electrochemical Potentiodynamic Reactivation test. The results showed that MA-M samples undergo more severe and rapid embrittlement than ST ones and a higher kinetics of sensitization due to small strains concentrated in grain boundaries and α′ martensite phase produced during the machining operations. The martensite phase is found to be quite stable at the sensitization treatment at 650°C. The increase of microvoids nucleation at the grain boundaries seems to be the mechanism of embrittlement in the sensitized 304 steel. [ABSTRACT FROM AUTHOR]

This work describes the behavior of ASTM A312 TP321 tubes heat treated at 600°C for periods of 1, 3, 10, 30, 40, 50, 60, 70, 80, 90, and 100 hours. The degree of sensitization that had occurred was assessed by Scanning Electron Microscopy (SEM) and by the Double Loop Electrochemical Potentiodynamic Reactivation test (DLEPR). The results showed that exposure at 600°C for 80 hours or longer caused severe precipitation of chromium carbides along the grain boundaries characterizing the sensitization of the material despite it being titanium stabilized. In order to minimize the sensitization process, solution annealing in the temperature range of 900-1100°C was studied. Solution annealing at 900°C was the best heat treatment in order to prevent sensitization at 600°C. The solution annealing at 900°C was also effective for samples from tubes that were sensitized after one year of operation in a refining plant. [ABSTRACT FROM AUTHOR]