Resumo em Inglês:

A series of CeαMn1-αO2 catalysts supported on γ-alumina with various molar concentrations of Ce (α, from 0 to 0.90) was synthesized by coprecipitation, applying two different precipitating agents, namely, sodium hydroxide (method 1) and sodium carbonate (method 2), with the use of sodium permanganate as a redox agent for precipitation. XRD profiles of the supported samples revealed the predominant abundance of a typical fluorite crystalline structure. TPR thermograms of supported samples were displaced towards lower temperatures with increasing Mn concentration, in contrast with the bulk samples. The supported Ce-Mn samples exhibited a greater performance in n-hexane elimination than did the corresponding simple oxides. The sample Ce0.33Mn0.67O2 obtained by method 2 presented the best activity, probably due to the enrichment of Ce4+, Mn3+ and Mn4+ surface species, an excess of superficial oxygen species and an easy reducibility as well as the lowest apparent activation energy.

Resumo em Português:

The trunk bark of Tabebuia caraiba Bignoniaceae was found to contain four novel iridoids, 6-O-E-p-coumaroyljioglutin D (2), 6-O-E-p-coumaroyl-3-demethyl-3-O-ethyljioglutin D (3), 6-O-E-p-coumaroyl-1-demethyl-1-O-ethyljioglutin D (4), 7-O-E-p-coumaroyljiofuranaldehyde (5), three known iridoids, including one iridoid glucoside, jioglutin D (1), rehmaglutin D (6), 6-O-E-p-coumaroylcatalpol (7). From the flowers were obtained six triterpenes, betulinic acid (8), olean-12-en-3-one (9), β-amyrin (10), oleanolic acid (11), ursolic acid (12), 3-O-E-p-coumaroylursolic acid (13), 2α-hydroxyursolic acid (14), 6β,19α-dihydroxyursolic acid (15), and one phenylethanoid, tyrosol (16), in addition to β-sitosterol, β-sitosterol-3-O-β-D-glucopyranoside and β-sitosterol-3-O-β-D-(6´-O-acyl)-glucopyranoside and E-p-coumaric acid. The structures of the isolated compounds were established on the basis of 1D and 2D NMR spectroscopic techniques. The chemical profile of the trunk bark of the plant was determined by HPLC/DAD/HRESIMS and did not present a good correlation with the phytochemical study. It did not detect most of the isolated substances and allowed to propose the presence of some non-isolated compounds.

Resumo em Português:

Intensive use of asphalt generates pollutants into the atmosphere which are harmful to the environment and worrying for occupational health. The application of asphalt products leads to emissions of significant concentrations of polycyclic aromatic hydrocarbons (PAHs) and particulate matter (PM) to the atmosphere. This paper aims to assess the pollutant emissions into the atmosphere in real conditions of asphalt paving through sampling and quantification of PM, Black Carbon (BC) and PAHs in fine particulate fraction and PAHs in gas phase. Concentration intervals of PM1.0, PM2.5, BC1.0 and BC2.5 found during a highway reconstruction in Londrina/PR were respectively 5.6-20.5; 6.3-24.2; 2.0-6.8 and 1.8-6.5 µg m-3. During asphalt surfacing at the same city’s central bus station, the concentration intervals were 15.1-75.1; 19.7-150; 5.1-14.6 and 4.9-16.2 µg m-3 for PM1.0, PM2.5, BC1.0 and BC2.5, respectively. PAHs in the gas and PM fractions were found in both situations with higher concentrations in the gas phase. The results of this work can provide useful information to society in order to improve practices and promote lower environmental impact and health protection.

Resumo em Inglês:

Phytochemical investigation of Endopleura uchi led to the isolation of a gallic acid derivate, known as bergenin (2) and friedelin (1), a pentacyclic triterpene. The present work also reports the bergenin quantification in different Endopleura uchi bark, twig and leaves extracts. Our findings showed the highest bergenin concentration in bark methanol extracts (4.75%) and the lowest concentration in twig aqueous extracts (1.89%). Phenolics quantification by Folin-Ciocalteu, revealed phenolic compounds level values from 16.69 to 43.02 mg GAE g-1 dry extract. The ferric reducing antioxidant activity ranged from 230.43 to 567.89 mmol Fe+2 g-1 dry extract. DPPH IC50 free radicals showed to range from 12.04 to 24.20 μg mL-1. Leaves’ chloroform fraction exhibited the highest nitric oxide inhibiting activity bearing IC50 = 3.2 μg mL-1. Results show this species to hold significant bergenin concentrations as well as phenolic and anti-inflammatory compounds in all extracts suggesting it bear therapeutic potential.

Resumo em Inglês:

The phytochemical investigation of the hexane extract which was obtained from the leaves of Xylopia laevigata (Annonaceae) produced six terpenes. Among these, five diterpenes named abieta-7,13-dien-3-one, ent-7β-acetoxy-16β-hydroxy-kaurane, 4-epi-cupressic acid, powerol, and labdorffianic acid B, and one oxygenated sesquiterpene, spathulenol. This is the first time these isolated diterpenes from X. laevigata have been described. The different structures belong to the abietane, kaurane, and labdane diterpenoids, and are indicative of the chemical diversity found in X. laevigata. Moreover, the diterpene ent-7β-acetoxy-16β-hydroxy-kaurane is reported herein for the first time as a natural product, and 4-epi-cupressic acid, powerol, and labdorffianic acid B are reported for the first time in the Annonaceae family. The structures of the isolated compounds were established by extensive analyses using 1D and 2D NMR spectroscopy in combination with MS. The cytotoxic activities of compounds abieta-7,13-dien-3-one, spathulenol, 4-epi-cupressic acid, and powerol were evaluated against tumor and non-tumor cell lines, in which spathulenol was found to be the most active, mainly against K562 with an IC50 value of 17.20 μmol L-1.

Resumo em Inglês:

Thermal decomposition of coffee husks was investigated by thermogravimetric analyses. The proximate, ultimate and composition analyses were performed. Thermogravimetric tests were realized, the material was heated to 1173 K using five heating rates: 5, 10, 15, 20, 25 K min-1. The kinetic parameters were estimated using the methods of Kissinger-Akahira-Sunose and Friedman, the distributed activation energy model and the independent parallel reactions model. The isoconversional models of Kissinger-Akahira-Sunose and Friedman showed the dependence between determined values of activation energy and mass conversion, the activation energy values varied from 1437.39 to 199.22 kJ mol-1 for Kissinger-Akahira-Sunose and from 127.81 to 230.35 kJ mol-1 for Friedman model. The values of activation energy were determined for Miura-Maki method; varying from 137.39 to 199.22 kJ mol-1. The model of parallel and independent reactions showed the presence of six different reactions (with activation energy values varying from 42.0 to 214.2 kJ mol-1) occurring during coffee husks pyrolysis, indicating a complex reaction. Currently, works regarding the determination of kinetic parameters for coffee husks pyrolysis are not common. The present work is the first report using the model of parallel and independent reactions to estimate kinetic parameters for pyrolysis of coffee husks, a residue widely generated worldwide.

Resumo em Inglês:

Aroma is one of the most important sensory attributes for acceptance by beef consumers. The first step in analysing the volatile compounds associated with this attribute is their extraction from the food matrix, solid-phase microextraction has been widely used for volatile compound determination in meat. This study aimed to test six different solid-phase microextraction (SPME) fibre coating materials for their volatile compounds extraction efficiency for roasted beef and to optimize the extraction conditions using response surface methodology. Gas chromatography coupled with a flame ionization detector (GC-FID) and mass spectrometry (GC-MS) were used. The choice of SPME fibre coating was based in the total area obtained by GC-FID analysis for the six fibre coatings. The optimum time and temperature for SPME extraction was 60 ºC/65 minutes. The mixed-phase fibre coatings showed the best results for extracting volatile compounds in roasted beef as higher number of compounds were identified. The carboxen/polydimethylsiloxane (CAR/PDMS) fibre extracted the largest number of compounds under the optimum extraction condition. Aldehydes were the predominant class of compounds found in roasted beef, followed by alcohols and hydrocarbons.

Resumo em Inglês:

Several studies have shown endocrine-disrupting effects of parabens. Parabens are a group of antimicrobials used as preservatives in a wide variety of products, mainly in personal care products. However, little information is available regarding the occurrence of parabens in baby products. In this study, the concentrations of five commonly used parabens, methyl-, ethyl-, propyl-, butyl- and, benzyl-paraben in 50 Brazilian baby wet wipes were analyzed by liquid chromatography coupled to mass spectrometry. All samples contained parabens, and the total concentrations ranged from 16 to 332,470 ng g-1 (geometric mean: 5344 ng g-1). Methyl-paraben, ethyl-paraben, propyl-paraben, and butyl-paraben were found in >65% of the samples. 24 out of 50 samples exceed the permitted value of 0.4 % for methyl-paraben for their use in personal care products. Although, propyl-paraben and butyl-paraben are forbidden in cosmetic products designed for application on the nappy area of children under three years of age, the detection rate of them were 94 and 70 %, respectively. Based on the measured concentrations and use frequency of baby wipes the estimated daily intake of parabens was calculated. The median estimated daily intake values of total concentrations of parabens for babies of one year old was 391 ng kg-1 bw day-1. In conclusion, babies and children may be exposed to high levels of parabens through use of baby wipes. It is also worth to mention that two forbidden parabens were frequently detected.

Resumo em Português:

A new method to identify the authenticity of Brazilian banknotes (R$) is proposed using digital image analysis by a smartphone application, Photometrix®, associated with chemometric tools. Authentic banknotes (n = 4) obtained in local bank and falsified (n = 12) by the author himself by means of three printers (laser-Deskjet®, wax-Color Qube® and inkjet-Deskjet®) were used for the development of the methodology. An experimental planning was performed to evaluate the authenticity of the banknotes determining: the best region (holographic band, tactile region in the lower left and right upper number, effigy microimpressions, lower number left, animal figure, watermark and puzzle); Region of Interest (ROI) (16x16; 32x32 and 64x64 pixels), focal length (8, 12, 15 and 20 cm) and variation of the smartphone (Motorola G5 Plus, Samsung S7 and LG K10). The best regions chosen were effigy microimpressions and round the animal. Promising results were obtained from ROI 16x16 pixels with focal length fixed at 10 cm. Thus, the application presents promising features for analyzing the authenticity of banknotes by digital images making it fast, non-destructive, portable, with low cost, and can be accessed by all society.

Resumo em Português:

Real-world vehicle emissions of carbonyls compounds (CC) were determined at the Rebouças Tunnel, Rio de Janeiro (Brazil). The tunnel is a two-bore tunnel with three lanes in each direction and has a length of 2840 m, divided in two sections. On average, approximately 5,000 vehicles (95% light duty) were passing the tunnel per hour. Sixteen samples were simultaneously collected 500 and 1500 m inside from the entrance. The main CC were formaldehyde, acetaldehyde, acetone, propionaldehyde and benzaldehyde. A total of 16 samples were collected in each point in 8 different days. In 5 days, CO and CO2 were also monitored during the sampling period. Emission factors were calculated. Using the Pierson method, emission factors were 7.5 ± 2.6 and 13.8 ± 5.7 mg km-1 for formaldehyde and acetaldehyde, respectively. Using the fuel consumption method, values were 6.3 ± 2.1 and 11.8 ± 3.9 mg km-1 for the same compounds. The differences between both methods were lower than 20% and may be considered acceptable considering all the approximations in the calculations. Ozone forming potentials (OFP) were also estimated as 90.4 ± 37.3 and 70.7 ± 24.6 mg km-1 for formaldehyde and acetaldehyde, respectively.

Resumo em Português:

In recent years, great advances have been observed in the proteomic area regarding the different approaches adopted as top-down, middle-down and bottom-up. Regarding middle-down and bottom-up approaches, a previous step for protein digestion is necessary for further analysis of the generated peptides. Classical digestion protocols employing proteases are usually carried out in solution, which can lead to a number of disadvantages such as high digestion time, enzymatic autolysis and impossibility to reuse the enzymes. In view of these drawbacks, different approaches have been studied and applied for improving enzymatic efficiency, inhibition of autolysis, reduction of digestion time, and to minimize the number of missed cleavages. In the literature, great efforts have been made in order to achieve maximum efficiency in enzymatic digestion, with emphasis on proteases immobilization. In this review, concepts related to protein digestion, immobilization techniques, as well as the main support used for enzyme immobilization are discussed considering new tools for proteomic analysis.

Resumo em Português:

A highly sensitive ultra-performance liquid chromatography tandem mass spectrometry method for the determination of Docetaxel and metabolites (M1+M3) in human plasma samples was developed and validated. The method employs a liquid-liquid extraction and a reversed phase separation Acquity® C18 column BEH C18 (150 x 2.1 mm, 1.7 µm). Mobile phase was a mixture of formic acid 0.1% (eluent A) and acetonitrile plus 0.1% formic acid (eluent B) in isocratic mode. Total analytical run time was 7 min. The interval of method linearity interval was 50 to 3000 ng mL-1 for docetaxel and 5.0 to 300 ng mL-1, for M1+M3 metabolites. Intra-assay and inter-assay precision was coefficient of variation 2.5-15.7% and 5.9-12.6%, respectively and accuracy was 89.0-114.0%. The method was successfully applied in the measurement of docetaxel plasma levels and area under the curve calculation in 31 cancer patients, demonstrating adequate analytical performance for the clinical application in the therapeutic drug monitoring and pharmacokinetics studies.

Resumo em Inglês:

The increase in demand for both fast and inexpensive prototyping of objects, with a certain degree of resilience and durability, is the main reason why 3D printing has become part of the concept of industry 4.0 and it is omnipresent in research facilities and industries around the world. In this work, we describe step-by-step the construction process of a filament winder that can be adapted for many commercially available bench-size polymer extruders. The electronic circuit used to regulate the winding rate, and therefore the thickness of the filament, is completely based on simple open-code microcontrollers such as Arduino Uno. Finally, it is showed that using this system it is possible to obtain printable ABS filaments with a wide range of thicknesses and a margin of error of around 5%.

Resumo em Português:

Studies conducted in the field of education have, in many cases, highlighted the little insertion of teaching and learning theories in Natural Sciences classes, in Higher Education. We developed this study to analyze how Chemistry professors take ownership of a historical case to explain the concepts they develop in their classes. To do so, we analyzed this record of undergraduate classes, at times when professors related pedagogical link-making to the future field of work of the students, using the “Thalidomide case.” We realized that, by showing the importance of studies involving chirality and related concepts, the students’ attention to the content seems to have increased significantly, which expands the possibilities of construction of meaning. Thus, we argue that the pedagogical link-making can significantly contribute to students’ knowledge.

Resumo em Português:

In Brazil, the continuing education of chemistry teachers has recently begun to form part of a broader public policy: the Professional Master Programs for the Qualification of Teachers of the Public Basic School (ProEB). The overall objective of these programs would be to contribute to the professional development by conducting qualified and current research that seeks to improve professional practices. Specifically, this article aims to present the perceptions of students and teachers in the initial phase of implementation of the Professional Master of Chemistry in National Network (PROFQUI). In this sense, the following are addressed: a) the aspects of teacher education in undergraduate chemistry courses; b) the continuing education of these teachers; c) the proposal of the professional masters, with special attention to PROFQUI; d) the initial data from a longitudinal survey involving 44 chemistry teachers and 27 university professors, collected from 6 higher education institutions participating in the PROFQUI. In short, it can be concluded that teachers of basic education seek from their professional development to improve the teaching of school chemistry. In this sense, such intended improvements are not only about scientific updating in chemistry, but also about didactic resources and possible practices and activities that contribute to their professional performance.

Resumo em Português:

On May 2019, the members of the Anthropocene Working Group completed a binding vote to affirm some of the key questions that have been agreed in 2016: the Anthropocene should be considered as a formal chronostratigraphic unit, defined by a Global Boundary Stratotype Section and Point (GSSP), using one of the stratigraphic signals around the mid-twentieth century of the Common Era. The fallout from nuclear weapons testing appears as the most suitable GSSP. In this article, the main anthropogenic markers are discussed as well as the sources or human-made radiation and the signature of nuclear weapons testing. The appearance of 239+240Pu in the early 1950s and the clear peak, in 1963, makes a good marker. High resolution archives include layers of sedimentary rocks, lacustrine and marine sediments and corals and polar ice cores. A coupled application of other radioactive isotopes, as 137Cs, 14C and 241Am, may be useful to categorize distinct fallout signatures. A site to define the Anthropocene (golden spike) would ideally be located between 30º and 60º north of the equator. Nevertheless, results obtained in sediments on the Brazilian coast showed that both 239+240Pu and 137Cs signatures could be detected and quantified as markers of this “atomic age”.

Resumo em Português:

The ability to monitor the spread of diseases is essential for prevention, intervention and control practices. In this context, wastewater-based epidemiology (WBE) has been applied to empirically evaluate the exposure of populations to chemical substances and pathogens of emerging concern in near real time. During the current COVID-19 pandemic, WBE remains an innovative epidemiological tool, with the potential to complement infectious disease surveillance systems. Recent studies on WBE and COVID-19 are based on the monitoring of viral RNA fragments as target biomarkers for SARS-CoV-2 via RT-qPCR and allied techniques. Literature results have been shown the potential of WBE as an innovative tool to monitor viral spread in large communities, map contagion curves and hotspots, identify the contribution of asymptomatic individuals, and subsidize early warning systems for disease outbreaks. WBE can offer less expensive responses for monitoring large populations compared to individual clinical tests which are not feasible on large scales. This aspect is important in terms of health surveillance and associated public policies, notably where clinical tests are scarce or underestimated and in less developed regions with inadequate sanitation conditions.