Resumo em Inglês:

This study describes the chemical composition and biological activities of extracts and compounds obtained from the roots of Bowdichia virgilioides (Fabaceae). A mixture of very long-chain free fatty acids (VLFAs) and pure compounds, namely isocordoin, cordoin, lupeol, lupenone, β-sitosterol, stigmasterol, and sitostenone, were isolated from the soluble fraction of the methanol extract by using sequential column chromatography procedures. The molecular structures of the compounds were determined using infrared (IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS) techniques. Notably, this is the first report of the occurrence of both chalcones within this plant genus. Besides, the VLFAs were identified by electrospray ionization mass spectrometry (ESIMS) and the presence of these compounds in roots is suggested to be an adaptive response to environmental stress, which exhibited moderate antioxidant properties when tested against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and in the β-carotene/linolenic acid auto-oxidation assay. However, the MeOH soluble fraction demonstrated significant toxicity in the brine shrimp lethality assay.

Resumo em Inglês:

Microparticulated whey protein can be used as a fat substitute in foods to enhance their nutritional value and improve their sensory and rheological characteristics. Microparticulation denatures whey proteins through heat treatment, followed by shear rate control to determine the aggregate sizes formed. The processing method used during microparticulation can modify the protein denaturation rate, which may enable the application of new proteins. This study sought to develop a methodology for quantifying whey protein fractions in commercial samples before and after microparticulation at different concentrations and physical states. The developed methodology proved to be applicable because of its selectivity, quantification, detection limits, and precision. The analyzed samples exhibited a higher denaturation rate for β-lactoglobulin than α-lactoalbumin; the denaturation rate varied among samples due to differences in the microparticulation process.

Resumo em Português:

In last decades, technical-scientific investigations into cultural heritage assets have increasingly become part of analysis methodologies accessible to professionals from different areas for a broad understanding of the complex material and historical nature of objects. In this interdisciplinary word, the painting “Costureiras” by Tarsila do Amaral (1886-1973), from 1950, was studied by ultraviolet-induced visible luminescence (UVL), infrared image (IR) and macro X-ray fluorescence scanning (MA-XRF) techniques. UVL and MA-XRF images enabled the exploration of the conservation status of the artwork, the creative process of the artist, and areas featuring materials distinct from the original painting. By combining the results of IR and MA-XRF images, it was confirmed that changes occurred in the creative process during the composition of the artwork. MA-XRF images further allowed the inference of the primary pigments employed by the artist, revealing that, during canvas priming, Tarsila do Amaral utilized pigments based on lead and zinc.

Resumo em Inglês:

The real-time sensing of benzene, toluene, ethylbenzene, and xylene (BTEX) vapor has become urgent due to their widespread hazards. As a sensing platform that combines low energy consumption and high sensitivity, moisture-resistant detection of ppb-level BTEX vapor remains a challenge for quartz crystal microbalance (QCM) based gas sensors. In this work, we employed polyaniline nanofibers as the sensing material, significantly enhancing the QCM sensor’s detection capability for BTEX vapor down to the 50 ppb level. Besides, thanks to the hydrophobicity of polyaniline nanofibers, this sensor shows minimal response fluctuations to BTEX vapor in the relative humidity range of 50-90%. Furthermore, this sensor exhibits a short response time and excellent long-term stability, thereby presenting a broad prospect for future industrial applications in BTEX vapor detection.

Resumo em Inglês:

In the present study a spectrophotometric method for Cr(VI) determination in organic fertilizers, especially those from tanning industry residues, is proposed. Conditions for chromium extraction, extract clean-up and analytical characteristics of the method were established. The method is based on the complexation of Cr(VI) with 1,5-diphenylcarbazide (DPC) in acid medium (pH 2.0). A mixture of NaOH and Na2CO3 solution at 0.125 and 0.07 mol L–1 (pH 12), respectively, and heating at 90 °C for 60 min were the best conditions for chromium extraction. Florisil and activated charcoal were tested for clean-up of the extract, with activated charcoal being effective. Under the established conditions, the calibration linear range is up to 2500 μg L–1 Cr(VI), the results obtained are in agreement with the value of a certified reference material (CRM041), precision is better than 5% for five consecutive determinations of a solution at 1000 μg L–1 of Cr(VI) and the limit of quantification is 1.62 μg g–1. In can be concluded that the method is robust, accurate and precise, and can be easily applied for the determination of Cr(VI) in routine analysis, since it complies with legislation of most countries regarding the maximum allowed concentration of 2 μg g–1 of Cr(VI).

Resumo em Inglês:

Bulk precipitation (BP) samples were collected at two coastal urban sites and two montane Atlantic Forest (400 and 1000 m altitude) areas in southeastern Brazil from August 2008 to August 2009. These samples were analyzed for the major inorganic ions (H+, Na+, K+, Ca2+, Mg2+, Cl- and SO42-) found in rainwater. The concentrations of inorganic nitrogen species (NH4+, NO3- and NO2-) were compiled from a previous study. The volume-weighted mean (VWM) concentrations of inorganic ions differed spatially, with higher values at the coastal urban and coastal periurban sites. On a molar basis, Cl- and Na+ together comprised 60% of the total inorganic constituents at the coastal urban site and 34-42% at the other three sites, as it is the closest to the ocean. Magnesium was also primarily associated with sea-salt aerosol. Non-sea-salt (nss) fractions of K+, Ca2+ and SO42- comprised 68-93% of their VWM concentrations, indicating the contribution of natural (mostly biogenic) and anthropogenic (SO2 oxidation for the latter) sources. Finally, we found that the acidity of BP at the four sampling sites is primarily controlled by the NH4+, nss-Ca2+, nss-SO42-, and NO3- ions, resulting in VWM pH values ranging from 5.60 (lower montane forest) to 5.98 (coastal periurban site).

Resumo em Inglês:

The aim of this study was to effectively remove Fe2+ by using ozone microbubbles in bottled mineral water to prevent sediment from occurring during storage and increase shelf life. By considering the characteristics of mineral water with low solubility of ozone and high CO2 content, a suitable ozone injection step was chosen and a new mineral water treatment method using microbubbles was proposed. As a result of the treatment of the bottled mineral water with ozone microbubbles, the concentration of the iron ion was reduced from 0.14 to 0.01 mg L-1, and the shelf life increased to 360 days. During the treatment, the concentrations of K+ and Na+ were almost unchanged, and the deposition time was reduced to one-third compared to the natural oxidation.

Resumo em Português:

To control vehicle emissions, the new homologation process must be reported according to the California Maximum Incremental Reactivity (MIR) scale’s procedure to calculate the ozone forming potential (OFP) of each new vehicle. This work calculates an MIR scale suitable for the Brazilian reality. Meteorological and hourly pollutant data from the Bangu Automatic Air Quality Station was inventoried and processed from March to September 2020 to adjust OZIPR Lagrangean model and obtain the MIR scale by making small increments in the concentrations of each volatile organic compounds (VOC) and calculate the ozone increase/decrease. It was found that the VOC that had the greatest impact on ozone formation was 1,2,4-trimethylbenzene, with 2.06 ppb O3 ppbC-1 VOC. The OFP was calculated based on the VOC emissions of a vehicle and it was found a value of 9.421 mg O3 km-1, a much lower value when compared using the California MIR scale of 136.608 mg O3 km-1. It is concluded that meteorological conditions and VOC speciation data in the air mixture in the studied region directly affect the photochemical reactions of ozone formation.

Resumo em Português:

Asphaltenes are complex molecules with a tendency to aggregate. This property can be an issue for the oil industry due to CO2 reinjection into reservoirs to mitigate these gas emissions. The present theoretical study aimed to study the CO2 interaction with no-substitute and substituted coronene as an asphaltene model compound at CAM-B3LYP-D3/6-311G(d,p) level. The electronic properties were evaluated using harmonic oscillator model of aromaticity (HOMA), quantum theory of atoms in molecules (QTAIM), and reduced density gradient (RDG) methods. The results showed that the coronene’s functionalization by a sulfur atom changes the coronene’s electronic structure. However, functionalization does not change the type of interactions between the monomers, as they remain predominantly van der Waals interactions. CO2 interaction with substituted coronene barely changed due to the presence of sulfur atoms. However, in dimers, the position of the heteroatom directly influences the interaction with CO2, although it is insufficient to change the interaction’s magnitude. For this reason, our results indicate that the sulfur heteroatom in asphaltenes should be addressed. However, new studies must be conducted by increasing the number of substituents, CO2 numbers, and the model size.

Resumo em Português:

The history of the discovery, use, and development of dyes is closely linked to the history of humanity itself. Among the first records of human civilization are cave paintings made from, e.g., fruits, plants, minerals, and insects. Over the centuries, using different techniques, colors have been given to all types of materials and products, from clothing to food. The chemicals responsible for colors are dyes - a vast collection of molecules of the most varied compositions, but which have in common the absorption of light within the visible window of the electromagnetic spectrum. This article aims not only to review the properties of some classes of natural dyes, their origins, and their applications but also to describe the various computational chemistry methods involved in designing new bio-inspired molecules.

Resumo em Português:

Over the last two decades, metabolomics has emerged as a pivotal tool in multidisciplinary research, providing invaluable insights into metabolome modulations and finding applications across various scientific domains, including medicine and agronomy. Nonetheless, the absence of standardized procedures in sample preparation, data acquisition, and documentation of data quality presents a significant challenge. This review underscores the critical importance of quality assurance and quality control (QA/QC) in untargeted metabolomics, advocating for the establishment of agreed-upon QA/QC reporting standards within the scientific community. We discuss the requisite quality controls at various stages of untargeted metabolomics studies, encompassing blank samples, pooled samples, and the utilization of external quality control samples. Methods for assessing accuracy, reproducibility, and identifying/correcting batch effects are addressed. Furthermore, emphasis is placed on standardizing the description of QA/QC data in scientific publications and repositories to foster reproducibility and transparency. We recommend the publication of QC data alongside studies in appropriate databases to facilitate data comparison and sharing among researchers, thereby enhancing the quality of untargeted metabolomics research. In summary, implementing standardized QA/QC data reporting, along with promoting best practices within the untargeted metabolomics community, is crucial for improving result quality and credibility and advancing research utilizing this powerful technique.

Resumo em Português:

The study of adsorption kinetics has been gaining ground, due to the fact that adsorption is an operation used in several areas, which drives the development of software for calculating kinetic parameters. In this context, the work aims to develop and validate a free software, with an intuitive interface and easy operation, for processing adsorption kinetic analysis data. The Adsorption Kinetics Calculation (AKC) software was developed in Java language, using Apache Netbeans IDE (integrated development environment) and has three kinetic equations implemented in a non-linear way: pseudo-first order, pseudo-second order and intraparticle diffusion implemented and also generates the parameters statistical coefficient of determination (R2) and ARE (average relative error). The software was successful in programming the algorithms, because the parameter values (Qe and C) were similar to the experimental values and the error values (R2 and ARE) were within those predicted by the literature. The software has the ability to plot the results and all results showed reliability in the data generated, and it can be concluded that it is validated and ready to be made available for users to use in their research.

Resumo em Inglês:

Gas chromatography coupled to mass spectrometry (GC-MS) has been widely used, and along with other methodologies such as derivatization, is a powerful tool to analyze phytocompounds, including cuticular wax components. The loss of structural information upon fragmentation of waxes makes it difficult to interpret and identify the GC-MS mass spectra of these compounds with the traditional methods, as digital libraries. Therefore, as a new complementary alternative to traditional methods of identifying aliphatic acyclic lipids based on mass spectra, we present the new software WaxAlly in this technical note. WaxAlly is a new software created based on simple algorithms, enabling the rapid recognition by the user of eight aliphatic acyclic lipid classes, including alkanes, alkenes, aldehydes, ketones, esters, and TMS derivatives of free fatty acids, primary and secondary alcohols, and their homologues with carbon chains varying between 10 and 100 carbons. Additionally, the WaxAlly software provides a section for data organization, internet comparison to NIST and PubChem databases, and academic information about mass fragmentation of acyclic lipids. The software has proven to be a very useful complementary technique in identifying plant wax lipid homologues, and new fragmentation patterns of lipid classes can be added in the future to improve the program.

Resumo em Inglês:

The ability to argue is essential for the education of students, as it is fundamental to the presentation of ideas on a given topic. Several methods have been proposed in studies that support the development of argumentation in different teaching contexts, such as the heuristic diagram. It allows the organization and recording of activities that enable critical reflection through the analysis of the language used to express ideas. In this perspective, the diagrams produced for solving problems in an experimental chemistry subject offered in an undergraduate chemistry course were analyzed. Toulmin’s argument pattern was used as a basis to identify the structure of the arguments produced, and then, the quality of the arguments was evaluated. The results of the analysis showed a principle of progress in the argumentative capacity of undergraduates with the development of activities, verified by the presence of elements in students’ texts that, when present, validate an argument. Thus, the results can contribute to other researches in the field of chemical education by favoring a teaching process that considers the development of initial argumentative ability in the formation of students.