Resumo em Inglês:

Catalyst performance is a relevant factor in biodiesel production because it can affect the efficiency of the process. This work provides a study of the performance of heterogeneous catalysts for biodiesel production derived from thermal-treated hydrocalumite-type compounds. This work aimed to synthesize and characterize hydrocalumite-type compounds intercalated with chloride and nitrate, evaluate the effect of thermal treatments at different temperatures (500, 600, and 750 °C) on these materials, and assess the performance of these materials as catalysts in the transesterification reactions using soybean oil and methanol. The materials were characterized by X-ray diffraction (XRD), vibrational spectroscopy (Fourier transform infrared with attenuated total reflectance (FTIR-ATR)), thermogravimetric analysis coupled to mass spectrometry (TGA DSC-MS), specific surface area, and X-ray photoelectron spectroscopy (XPS). The results of the transesterification reactions showed that the thermal-treated materials from the hydrocalumite intercalated with chloride presented high catalytic activity, among them, the thermal-treated material at 750 °C presented the highest conversion to methyl esters.

Resumo em Inglês:

Oil-in-water emulsions containing N,N-diethyl-3-methylbenzamide (DEET) were developed aiming to extend the sustained release of the active compound, by using two oppositely charged nanomaterials, namely silica nanoparticles (SiNP) and cationic cellulose nanofibrils (CCNF), as stabilizers, and a mixture of food-grade nonionic surfactants to avoid precipitation by electrostatic aggregation. The formulations were stable for more than four months at room temperature, and strongly resistant to destabilization upon centrifugal and thermal stress. The results were correlated with the effect of SiNP on strengthening the network formation of CCNF in the aqueous phase by electrostatic interactions, which increased the viscosity of the external phase and, hence, emulsion stability. There was a significant size reduction of the internal oil phase containing DEET in the presence of CCNF, which was attributed to the increased viscosity in the external aqueous phase, as well as to interfacial stabilization. The combined action of CCNF and unmodified SiNP in the stabilization of the DEET-containing oil phase significantly decreased the release rate of the active compound, compared to non-emulsified DEET. Moreover, in the emulsions containing the CCNF/SiNP mixture there was a more sustained release for the period of 6 h, demonstrating the potential of these formulations for extended protection.

Resumo em Inglês:

Multi-drug-resistant bacteria (MDR) are the cause of different infections and diseases that have affected humanity for a long time, and have been an emerging global health problem that has led to increased morbidity and mortality. The growing emergence of MDR bacteria has underlined the need for development and discovery of new antibacterial compounds. In this context, a series of new paeonol 1,2,3-triazole and ether derivatives were synthesized using copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction and nucleophilic substitution. Paeonol has been a natural product widely studied due to its many biological activities, as well as its derivatives. Three ether derivatives (two unpublished) and ten triazole derivatives (six unpublished) of paeonol were obtained, which were determined by nuclear magnetic resonance (NMR), Fourier transform infrared spectrometry (FTIR), Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and six of them by X-rays, which is the first study of this type presented for these compounds. All the synthesized compounds were evaluated as antibacterial agents against Staphylococcus aureus and Escherichia coli, obtaining a minimum inhibitory concentration (MIC) above 100 µg mL-1. The results showed that CuAAC and nucleophilic substitution were very useful to obtain new paeonol triazole and ether derivatives and the products were obtained in yields from 21.3 to 98.5%. The advantages of these reactions (high yield in most compounds, reaction time, low impurities) show that using the method to produce new derivatives is advisable thus assisting in the discovery of new potential bioactive compounds.

Resumo em Inglês:

LaNiO3 material was synthesized by modified proteic method, calcined at 900 °C/2 h in air atmosphere and was applied to remove environmental contaminants. LaNiO3 phase with a perovskite structure was formed in the calcined material, which has a surface area of 22 m2 g-1 and is formed by fine particles agglomerated, with pH of the zero charge point of 7.44. The removal of a model pollutant (Turquoise Blue dye) indicated that the better removal occurs in acidic pH and with adsorbent’s mass of 50 mg, showing average value around 90% of removal efficiency and 131 mg g-1 for adsorption capacity (q) value. The variable constants model was the one that best fit the kinetic. LaNiO3 material resisted the test conditions and the recovery process, and maintained its high adsorption capacity throughout the six regeneration cycles studied, which indicates that it is a promising material as an adsorbent of pollutants and does not generate waste during the process.

Resumo em Inglês:

The objective of this study was to evaluate the effect of pasteurization, lyophilization and spray-drying on the lipid profile of donated human milk (DHM) at different lactation stages. Nine frozen samples of colostrum, transitional and raw mature human milk (HM) were collected from the Human Milk Bank (HMB) of the Hospital Universitário de Maringá (HUM). Samples were thawed and pooled according to lactation stage. Thereafter, it was submitted to pasteurization, lyophilization and spray-drying processes and later the fatty acid (FA) composition and the lipid profile analyses were performed. Gas chromatograph (GC) with flame ionization detector (FID) and electrospray ionization (ESI) mass spectrometer (MS) were used, respectively. In the FA composition analysis, it was observed that the same classes of saturated FA (SFA), monounsaturated FA (MUFA) and polyunsaturated FA (PUFA) were preserved throughout the process and in all lactation stages. The lipid profiles were also preserved after processing. Therefore, the lyophilization and spray-drying processes are promising techniques to preserve the DHM in the HMB, once the components evaluated were preserved, and both techniques facilitate the transport and storage, as the techniques reduce the sample volume.

Resumo em Inglês:

There is robust evidence of the hypochlorous acid (HClO)-mediated damage in biomolecules, and nicotine boosts the chlorination potency of HClO. We present experimental and theoretical evidence of the mechanism by which nicotine catalyzes the chlorination of pyranine. The rate constants for chlorination of pyranine by HClO were measured in the presence (5.3 × 105 mol 1 L s-1) and absence of nicotine (4.2 × 103 mol-1 L s-1), revealing the catalytic effect of the alkaloid. Density functional theory (DFT) calculations, based on B3LYP-GD3(BJ)/6-311++G(3df,2p)/SMD(Water)//B3LYP-GD3(BJ)/6-311++G(2d,p)/SMD(Water) level of theory, were performed and showed a decreased activation energy for chlorine transfer and hydrogen abstraction when nicotine chloramine intermediated the reaction. The atomic polar tensor (APT) charges on the chlorine atom of HClO (+0.084) were lower than the chlorine of nicotine chloramine (+0.149), revealing the higher electrophilic character of nicotine chloramine. In conclusion, the increased electrophilic nature of HClO provoked by nicotine explains its catalytic effect.

Resumo em Inglês:

This study evaluated the pollutant levels (NO2, SO2, CO, and O3), air quality index (AQI) and the influence of meteorological variables and coronavirus disease (COVID-19) pandemic on the air quality in Rio de Janeiro. The data set used comprises periods before (March-April, 2019) and during pandemic (March-April, 2020). According to the AQI results, on most days, the air quality was ranked as “good”. Brazilian air quality standards for SO2, O3, and NO2 were not exceeded in any of the monitoring stations during partial lockdown, while CO exceeded in all periods in one site due to industrial emission. Comparing both periods, descriptive statistics for the meteorological parameters presented no differences, which suggests similar conditions. However, when evaluated week by week in 2020, weather conditions presented some differences that probably affected pollutant concentrations. The correlations between O3 and NO2 and some meteorological parameters indicate that variations in both favored ozone formation, since it is a photochemical process favored by temperature and solar radiation and that, in Rio de Janeiro, low NO2 concentrations lead to increased O3. The improvements on air quality during the partial lockdown may be attributed mainly to a reduction on emission sources rather than weather conditions.

Resumo em Inglês:

One of the main phenomena causing problems in the oil industry is the precipitation of waxes, which can crystallize and form deposits, clogging lines and reducing flows. Many studies have been conducted seeking to overcome this problem, mainly through application of chemical to increase flow. Some studies have shown that the asphaltenes present in crude oil can also be involved in the process of wax deposition. In this study, model systems were investigated to determine the influence of a natural additive, a chemical additive and their combined use on the fluidity of the samples. The natural additive, consisting of a refinery asphalt residue (ASPR), was studied in relation to the influence of its aggregation states on the fluidity of the wax model systems. All samples were evaluated through the pour point test, according to the ASTM D-97 standard. The results indicated that both the ASPR and the commercial poly(ethylene-co-vinyl acetate) can improve the fluidity. Synergistic effect, using both together, was verified by the significant reduction of pour point for model systems with wax content as high as 13% m v-1. That action was closely related to the concentration of ASPR and its aggregation state, as indicated by tests with different wax concentrations.

Resumo em Inglês:

Supported Au-Pd nanoparticles (NPs) have been extensively studied in alcohol oxidation reactions. However, few studies use reducible metal oxides as support, which can activate oxygen molecules and boost the selectivity of the reaction. In this work, Au-Pd NPs were supported on α-MoO3 and evaluated in the selective oxidation of cinnamyl alcohol without solvent. The Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoemission spectroscopy (XPS) analyses showed that the catalyst is richer in oxygen vacancies than the support, being probably responsible for the stability of the NPs (average size 4.62 ± 0.15 nm) and the high conversion and selectivity for the oxidation of cinnamyl alcohol. Furthermore, experiments have shown that the Au:Pd molar ratio influences the catalytic performance and can be optimized by controlling temperature, pressure, and reaction time. The catalyst proved to be active and selective for cinnamaldehyde in short reaction times. It showed satisfactory performance at 30 min and its best activity at 1 h with 94% conversion and 87% selectivity, without loss of activity and selectivity after four runs under the same reaction conditions.

Resumo em Inglês:

In this study, xiquexique (Pilosocereus gounellei) native endemic cactus from the Brazilian semiarid was used for the first time as a natural carbon source (“green precursor”) for the synthesis of highly fluorescent carbon dots (CDs). These CDs were successfully used to develop a fast, low-cost, eco-friendly fluorescence method for the determination of tannins in teas. This method was automatized employing a flow-batch system coupled to an inexpensive ultraviolet light-emitting diode (UV-LED) used as an excitation source and a cheap handheld spectrometer used as a detector. CDs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis, and fluorescence spectroscopy. The proposed method presented a linear range from 2.0-30.0 mg L-1, relative standard deviation (RSD) < 3.0%, limit of detection (LOD) = 0.102 mg L-1, and recovery rates from 90.5-109.1%. A paired t-test at a 95% confidence level indicated no statistically significant difference between the proposed and reference methods, revealing that it is a useful alternative for the determination of tannins.

Resumo em Inglês:

This study proposes a screen of variables that have an influence on the modification of the bio-oil chemical composition as a unique critical quality attribute (CQA) throughout the pyrolytic process (zeolite, ZSM-5) by using a 24 full factorial design, followed by optimization through a response surface methodology (RSM) based on central composite design (CCD) involving samples of biomass sorghum BRS716 (Sorghum bicolor L. Moench). The pyrolysis of pure biomasses and the biomass impregnated with the catalyst was carried out in a vertical bench furnace at 500 °C. Screening design involved factor variation in two levels (-1 and +1) of four variables as critical process parameters (CPPs) such as furnace heating rate (°C min-1), nitrogen flow (mL min-1), amount of biomass (g), and catalyst (% m/m), leading to obtaining bio-oil. Thus, it was possible to create a response surface from these two variables (biomass and catalyst), in which a minimum critical point was reached. The production of a bio-oil rich in hydrocarbon compounds is possible, but a large amount of catalyst was required. Two analytical techniques based on gas chromatography coupled to mass spectrometry (GC-MS) and mid-infrared (MIR) spectroscopy, provided additional information to fully characterize bio-oil chemical composition.

Resumo em Inglês:

The identification and analysis of documentary fraud is always a challenge for forensic science. Document analysis has proven to be an important branch of forensics in elucidating the authenticity of documents. The development and incorporation of luminescent inks in authentic documents have proved to be an excellent security feature. This paper purposes the use of a possible luminescent ink marker for anti-counterfeiting applications, aiming to create a document encoding process that is simple, robust, sensitive, and non-destructive. Since luminescent inks markers provide a visual, chemical, and spectral signature, and can be easily detected by using a UV lamp, the aid of unsupervised chemometric tools makes it possible to differentiate the luminescent markers inserted in the ink. Unsupervised models of principal component analysis (PCA) and K-mean were successful in correctly associating marked inks with their respective pure markers, while a supervised classification model based on partial least squares discriminant analysis (PLS-DA) correctly classified all samples from the prediction set and the blind test samples. For comparison, a soft independent modeling of class analogy (SIMCA) model was also built, which despite showing a misclassified sample it is also a strong candidate for future applications.

Resumo em Inglês:

This study aims to analyze Tetragonisca angustula honey from southwestern Bahia for its physicochemical characteristics, phenolic compounds and glioma cell inhibitory effect, in samples from different periods of the year, dry (DP) and rainy (RP) period. The analyses showed that samples obtained in the DP and RP are statistically different for the physicochemical profile (p < 0.05). DP honey has a darker color, greater acidity, content of reducing sugars and ash and lower moisture, when compared to RP. The content of total phenolics and flavonoids was determined spectrometrically, using the Folin-Ciocalteu method and reaction with aluminum chloride, respectively, and there was no statistical difference between the samples (p > 0.05). For the extraction of phenolic compounds, dispersive liquid-liquid microextraction was used, besides analysis by high-performance liquid chromatography with ultraviolet detection (HPLC-UV), which identified chlorogenic acid and quantified caffeic acid and rutin (1.7723 and 0.9384 μg 100 mg-1 honey, respectively). Glioma cell inhibition effect lines were observed for DP at concentrations 1000 ng mL-1 of honey. Principal component analysis (PCA) proposes the physicochemical parameters as the main distinguishing factors between the DP and RP samples. DP samples showed similarity for the parameters ash content, acidity and reducing sugars and the samples of the RP had consonance between pH and moisture.

Resumo em Inglês:

Cariniana estrellensis (Raddi) Kuntze seedlings have been used in forest restoration programs in the Atlantic Forest biome. However, despite the economic and ecological relevance of this species, to date no general method for rapid identification of primary and secondary metabolites of C. estrellensis leaves has been reported. In this work, we explore the feasibility of using rapid analysis by nuclear magnetic resonance techniques and liquid chromatography coupled to diode array, charged aerosol, and mass detection. The main secondary metabolites identified were hydrolysable tannins, quinic acid, hydroxycinnamic acids (trans-p-coumaric acid, cis p coumaric acid, and trans-ferulic acid), and flavonoids (kaempferol and quercetin derivatives). These compounds are particularly useful as chemotaxonomic markers for the genus Cariniana and for the family Lecythidaceae, and may also be important for pharmacological uses and for the survival of the seedlings in reforestation programs.