Resumo em Inglês:

According to the inventories carried out by the air pollution control agencies, vehicle emissions are responsible for more than 70% of air pollutants in metropolitan regions. Proper handling of CMAQ input data is an important step in the formation of a database for the model. Thus, it is necessary to insert the meteorological data using the Weather Research and Forecasting (WRF) version 3.9 in the period of the 31 days of January 2013. Four domains with resolutions of 27, 9, 3 and 1 kilometers were used and 21 vertical layers. Spatial Allocator (SA) was used to format the maps and extract the data necessary for the construction of the SMOKE emissions inventory files. WRF was validated comparing the simulation results with data from two weather stations (Jardim Primavera and Nova Iguaçu), using the statistical methods MB, MAGE, RMSE and IOA. SMOKE presented a constant time profile, this occurred because the established hourly function only contemplated daily results without taking into account the variations over the week.

Resumo em Inglês:

Cyanobacteria produce a wide variety of bioactive compounds, making them a highly promising group in the search for novel molecules with pharmacological and biotechnological properties. Among these, microginins attract attention for being peptides which inhibit angiotensin-converting enzyme, turning them into potential targets for hypertension and congestive heart failure treatment. This work describes a rapid and sensitive method for untarget screening of microginins in cyanobacteria extracts by LC-QqQ-MS/MS. These compounds are mostly characterized by containing 3-amino-2-hydroxy-decanoic acid at the N-terminus, which often could be chlorinated, dichlorinated or methylated. Based on the fragment ion arising from this decanoic acid derivative, a precursor ion scan (PIS) strategy has been proposed. This approach identified suspect microginins in cyanobacterial strains and environmental samples that were later confirmed by LC-QTOF-MS/MS. Eight new microginins structures were characterized based on the obtained fragmentation spectra from a total of 19 variants detected. This study highlights the applicability of PIS mode acquisition for untarget screening, detecting a wide variety of microginins with amino acids modifications, produced mainly by Microcystis aeruginosa strains. This method is a useful tool for the identification and environmental monitoring of molecules with conserved molecular substructures that possess similar fragmentation pattern

Resumo em Inglês:

In this work, the process of synthesis of Metal-Organic Frameworks containing lanthanide ions (LOFs), accelerated via a precipitating agent, capable of accelerating the process of nucleation of MOF crystals, in order to explore the optical properties of this precursor solution (SP_Gd/EU-MOF), as a quick-response photoluminescent material in the coding of official documents. The SP_Gd/Eu-MOF was deposited on the paper substrates manually, using pilot board master liquid ink pens with medium tip. The SP_Gd/Eu-MOF, was characterized by photoluminescence spectroscopy after crystallization on a vial and at surface of the papers, and the spectra showed identical spectral profiles, showing that the interaction with the substrate surface did not promote significant changes in the site symmetry of Eu3+ ions. After being deposited, the material was excited by UV radiation (λ = 254 nm), and emitted the red color characteristic of the Eu3+ ion. The SP_Gd/Eu-MOF, showed good mechanical stability in the abrasiveness test carried out with a rubber remaining deposited on the substrate, demonstrating it is potential to act as proof of authenticity in the encoding of documents, revealing itself as another low cost alternative for the deposition of photoluminescent inks.

Resumo em Inglês:

The phytochemical investigation of the hexane and methanol extracts from the bark of Duguetia pycnastera Sandwith (Annonaceae) afforded seven known compounds, two asarone-derived phenylpropanoids and five isoquinoline-derived alkaloids. The asarones, γ-asarone (1-allyl-2,4,5-trimethoxybenzene) and 2,4,5-trimethoxy-styrene were isolated of the hexane extract while the aporphine alkaloids, O-methylmoschatoline, lysicamine, nornuciferidine, and guatterine N-oxide, and the benzyltetrahydroisoquinoline alkaloid, (S)-reticuline were isolated of the alkaloid fraction of the methanol extract. This is the first report of these compounds in D. pycnastera. γ-Asarone is being reported for the first time in the Annonaceae. Nornuciferidine is described for the second time in the Annonaceae while guatterine N-oxide is the third register. The structures of the isolated compounds were established by extensive analyses using 1D and 2D NMR spectroscopy in combination with MS. The cytotoxic activity of the isolated compounds (except for nornuciferidine) was evaluated against cancer and non-cancerous cell lines, in which lysicamine was the most active compound, mainly against HL-60, HepG2, and K562 with IC50 values of 24.40, 28.86 and 38.75 µmol L-1, respectively.

Resumo em Inglês:

Fridericia speciosa (Bignoniaceae) is a liana that occurs in humid to dry vegetation in eastern and southeastern Brazil. Species belonging to the genus Fridericia are employed as medicinal plants. This study evaluates the antipromastigote and cytotoxic activities of the crude extract, fractions, and compounds isolated from F. speciosa, and an HPLC (High-Performance Liquid Chromatography) analytical method was used to quantify the bioactive flavonoids. The flavonoids alpinetin (1), luteolin (2), diosmetin (3), and apigenin (4) were isolated from the active EtOAc-soluble fraction (EAF) of the crude ethanol extract (LCE) obtained from F. speciosa leaves. Both LCE and EAF were active against the normal human lung fibroblast cell line GM07492A (IC50 of 460.7 µg mL-1 and 381.4 µg mL-1, respectively). Only EAF showed activity against Leishmania amazonensis (80.4% at 50 µg mL-1). Compounds 1 and 2 were quantified by HPLC-DAD in both LCE (1: 6.21%; 2: 1.11%) and EAF (1: 45.32%; 2: 2.00%). At 100 µM, compounds1-4 inhibited L. amazonensis flagellar motility by 40.2%, 26.8%, 1.0%, and 24.8%, respectively, while their toxicities (IC50) to the normal cell were > 1000, 353.0, 766.2, and >1000 µg mL-1, respectively. Therefore, F. speciosa leaves are a prolific source of bioactive flavonoids.

Resumo em Inglês:

The voltammetry is an important analytical technique and also useful for pKa determination. It is a usual procedure of this technique to employ inert electrolyte concentration 100 times higher than redox compound concentration further a pH buffer. However, the ionic strength changes with the solution pH. In this work, we study the consequences of this procedure by using a model system, aniline. A differential pulse voltammetry was used with a glass carbon electrode in 4.0 x 10-3 mol L-1 aniline, 0.04 mol L-1 Britton-Robinson Buffer, NaNO3 as inert electrolyte and pH from 2.0 up to 7.0. The first oxidation peak (0.67V ca.) was used. The pKa determination was performed by using intersection lines at Epeak versus pH. This method was also theoretically discussed for both the oxidant or reducing compound with Brönsted acid-base behavior. For the cited procedure, the ionic strength changed from 0.418 to 0.528 mol L-1, and the experimental pKa (5.691) was far from theoretical one (4.722), still a good fit of lines to experimental data. Using the correct procedure, the experimental pKa (4.938) was near the theoretical one. Therefore, we have proved the need for a more careful adjust of ionic strength in this application.

Resumo em Inglês:

In this study, electrochemical impedance spectroscopy (EIS) is evaluated as a novel application in the biodiesel purification process. EIS is proposed as a tool to study the behavior of charge carriers produced from side reactions or dissociations of some impurities during the gravitational separation of glycerol dispersed in crude biodiesel after the transesterification process. In the present study, EIS combined with a simple capacitor of two parallel plates made of stainless steel ASTM 304 with an area of 7.0 cm2 and a gap between the plates of 0.8 mm is demonstrated to be a promising technique to monitor the biodiesel/glycerol separation as a function of time. From the analysis of the impedance data, collected during the separation process, it was found that the biodiesel resistance increases up to a maximum value and then decreases to a value which corresponds to the final equilibrium state. Considering that the maximum resistance represents the less contaminated biodiesel as a criterion, the proper average biodiesel/separation time of 4 h 14 min ± 1 h 11 min was determined. Another finding from the EIS results suggests that a growing absorbed film exists on the plate surface of the capacitor used as an impedance sensor.

Resumo em Inglês:

In this study, we propose a novel method to determine the vitamin C content in fruits and vegetables. The proposed method exploits the image and data processing abilities of computers by coupling a digital camera and a color reaction. An image acquisition device was developed to collect the image information of the solution to be measured after the color reaction. The corresponding RGB and Lab color components were obtained by an image analysis software. Further, the standard curves of the vitamin C concentration and color component were established by nonlinear, linear, and multivariate data fitting. The detection range was 0.81-20.00 µg mL-1 (R2 = 0.9994), LOD was 0.24 µg mL-1, LOQ was 0.81 µg mL-1, accuracy was 98.95%, and precision was determined with an RSD of 0.73%. A comparison of the results confirmed that the proposed method’s accuracy was higher than that of the spectrophotometric method. The proposed method has a simple design and facilitates easy operation, and the cost of the equipment is only US$ 31.43. Therefore, it can replace the traditional spectrophotometric method for the determination of vitamin C content in fruits and vegetables and is highly applicable in the food, chemical, and medical fields.

Resumo em Inglês:

The organic matter (OM) contained in a natural aquatic environment, located in a tropical region in Notheastern Brazil, was characterized using synchronous fluorescence spectroscopy and UV-Vis absorbance. The synchronous fluorescence spectra did not show qualitative differences for samples collected during dry and rainy seasons. They also revealed two peaks, one at 390 nm and other at 460 nm, associated with humic substances. The lack of peaks with significant fluorescence intensity at 270 - 300 nm and at 320 - 370 nm confirms it is an environment with natural OM. The A254/A436 ratios obtained during the dry and rainy seasons (13.55 to 14.97) indicate the presence of allochthonous OM of terrestrial origin, with high level of aromatic carbon associated with humic substances. The OM photodegradation by natural sunlight was more pronounced in the first five days, with a decrease of FImax from 23.6 to 55.4%. Also, titration with Cu(II) ions was used to determine the complexation ability of the two fluorescent sites, obtaining log K values of 4.26 and 4.27.

Resumo em Inglês:

Thiacloprid (TCP) is a synthetic insecticide, belonging to the class of neonicotinoids (NNCs), which present potential damages to the environment, biodiversity and human health, being necessary its constant monitoring. In this sense, molecularly imprinted polymers (MIPs) have been shown as an excellent alternative for the separation science, since they can recognize molecularly and selectively the analyte in various types of complex sample, such as food, soil, etc., thus contributing to its efficient extraction. In the present work, we have investigated, through DFT calculations, the mechanism of formation of a MIP for the TCP. As main result we obtained the following theoretical protocol for the MIP synthesis: 2-(trifluoromethyl) aryl acid (TFMAA) as FM (functional monomers), in 1:3 stoichiometry, and toluene as the solvent. This theoretical protocol showed the most favorable stabilization energies for the pre-polymerization complexes formed. In addition, it has been shown that the establishment of hydrogen bonds between the TCP and FM play a fundamental role in the stability of the complexes formed. We consider this work quite relevant since it can be used by experimentalists in order to reach an efficient MIP synthesis for TCP.

Resumo em Inglês:

Polymeric bionanocomposites are versatile materials that have many practical applications. The wide use of these materials is mainly due to their structure and properties, which combine at nanometric scale, the functionality of biopolymers with the excellent stability of inorganic solids, such as the clay minerals family. Montmorillonite is the most widely employed clay mineral in the development of polymeric bionanocomposites. The resulting materials from the combination of biopolymers and montmorillonite clay can form different structures (layered, delaminated, and exfoliated phases) and morphologies (powder, films or beads), exhibiting new features and better chemical, mechanical, thermal, and gas barrier properties compared to the pristine matrices, owing to the synergistic effect between both organic and inorganic moieties. In this sense, this review addresses polymeric bionanocomposites originating from the interaction between montmorillonite and chitosan and cellulose biopolymers. The synthesis, characteristics, and main applications of polymeric bionanocomposites have been reported, and in some cases, the relationship between the formed structures and final properties of bionanocomposites is also highlighted.

Resumo em Inglês:

We perform an analysis of plasmonic nanomaterials in a two part review, the first of which constitutes the present work. Here, attention is given to the fundamentals of metal nanoparticle optical properties. It is discussed the principles regarding the excitation of localized surface plasmon modes in nanostructures of different sizes, shapes and surrounding media. The discussion is used as basis for the analysis of local properties derived from such excitations, which are used for the introduction of surface-enhanced Raman scattering (SERS). Throughout the review, the fundamentals of plasmonic excitations and their mechanisms of relaxation are used to introduce chemical applications of metal nanoparticles in different areas such as the construction of analytical chemistry sensor devices, enhanced molecular spectroscopy and plasmon-mediated chemical reactions (also referred to as plasmonic photocatalysis).

Resumo em Inglês:

In this second part we will discuss how surface chemistry properties of plasmonic nanomaterials can be tailored by applying coordination chemistry, supramolecular and materials chemistry approaches, in which nanoparticles with well-controlled features conjugated with properly chosen molecules are the basis of functional organized structures that can be applied as high sensitivity sensors and high efficient photocatalysts. To achieve this level of control the interactions between the nanomaterials surface and the chemical environment surrounding it, the metal-ligand interactions on the materials surface and the electrons and energy transfers at the interface should be well understood. Therefore, we will show how the Surface Enhanced Raman Effect (SERS) can be explored to study the nanomaterials interface. Finally, we will discuss the role of plasmonic nanomaterials in sensors, more specifically SERS sensors, and photocatalysis.

Resumo em Inglês:

In recent years, the consumption of organic foods has considerably increased. The basic difference between organic and non-organic food products is the way in which they are produced and processed, and the authenticity of these products is a current trend in food science and analytical chemistry. In this sense, the objective of this work was to propose an analytical methodology based on near-infrared spectroscopy (NIR) coupled with partial least squares with discriminant analysis (PLS-DA) for authentication of organic Origanum vulgare L., a spice known for its characteristic aroma and among the most popular condiments in the world, receiving prominence for its antimicrobial, antioxidant and anti-inflammatory properties. As a result, NIR/PLS-DA was able to promote a rapid and non-destructive analysis in the authentication of organic samples. Important spectral regions for this authentication were highlighted by VIP scores being from 1350 to 1430 nm, and from 1450 to 1480 nm where it is observed absorption due to ROH, ArOH, CONH2, RNH2, CONHR, CH, CH2, and CH3.

Resumo em Inglês:

The use of anabolic androgenic steroids is largely restricted worldwide since they are associated with innumerous side effects and health damage. However, apprehensions of formulations of anabolic agents have been extensively increasing throughout the world, making their analysis a common task in the forensic field. In this sense, a set of three experiments was developed and applied to undergraduate students of Forensic Chemistry dealing with visual inspection of apprehended formulations of anabolic androgenic steroids as well as chemical identification by Infrared Spectroscopy and Gas Chromatography-Mass Spectrometry. Moreover, the classroom evaluated the extraction of steroidal active ingredients by ultrasonic and microwave-assisted extraction. The experimental procedures allied with the theory behind these topics provided an important background to the students on distinct extraction methods and analytical techniques used in the analysis of anabolic agents. Finally, the classroom was led to critically evaluate and interpret the results as well as to question the adequacy of experimental methods used in forensic analysis to stimulate their critical thinking.

Resumo em Inglês:

This paper discusses 286 proposals and reports of Green Chemistry (GC) teaching experiences, in papers of the Journal of Chemical Education (JCEd) until 2019. The analysis was based on previous categories: source-problem, paper focus, subjects/area of knowledge, target groups, GC contents, type of approach and purpose(s) of the proposal. A list of possible characteristics of each category served as an example to compare with the information resulting from the analyses, and thus improve the discussions. In 127 papers, GC and its teaching were associated, albeit generally, with the theme of sustainability/sustainable development, which points to its potential to face environment-related aspects of chemistry in teaching. A systemic vision in the interconnection between GC and sustainability/sustainable development appeared more explicitly in 39 papers up to 2019. So far, the analysis highlights a certain reproduction of traditional chemistry teaching, and little evidence of the particularities of GC teaching. Despite the intention of inserting GC into chemistry teaching, proposals for its incorporation are often made superficially, more as an addendum or an extra quality than a specific goal. More methodological detail of the experiments carried out is needed to help in the dissemination of GC in the training curriculum of chemists. The discussions and reports on teaching approaches based on Systems Thinking showed the opening of a promising new methodological challenge within this theoretical paradigm.

Resumo em Inglês:

This work describes the importance of using renewable sources in experimental classes for undergraduate students, as well as to spread the ideas of using biomass wastes as a source of products of interest. Therefore, in the proposed experiment, citrus fruit peel waste was employed to obtain pure flavonoids by extraction and recristalization. These procedures are important to reveal to students how bioactive products can be easily obtained from natural sources. In this way, naringin and hesperidin could be efficiently extracted from grapefruit (Citrus x. paradisi L.) and common orange (Citrus sinensis L. osbeck) peel wastes, respectively, using simple alcohols as solvents.

Resumo em Inglês:

The thematic approach supported by Paulo Freire’s reference has been the object of study in the Teaching of Nature Sciences. In this work we analyzed which knowledge is explained by two undergraduate students about limits and potentialities related to the planning and development of a thematic approach promoted in the context of a supervised curricular internship of a degree course in Chemistry. The examination of the knowledge of the graduates registered in a collective virtual diary was guided by assumptions from the perspective of the teacher as researcher of the practice itself and the procedures of discursive textual analysis. The analysis highlights that part of the knowledge explained by the undergraduates refers to the choice of topic and content of Chemistry to be addressed and the organization of classroom activities, which sometimes move away from a progressive perspective of education. Finally, it is pointed out that certain knowledge explained by the students as a potentiality in the thematic approach may keep in itself a certain limit that needs to be problematized, reinforcing to some extent the importance of the theoretical-methodological approach that guided the formative process.

Resumo em Inglês:

This work describes a methodology to carry out the analysis of technological sectors, using information contained in patent documents. The use of this information by professors and students of chemistry courses and related areas is still little used. The consequence of this is the repetition of efforts to obtain some results of research and development. The use of patent big data and the construction of scenarios, using several variables, is even rarer in Brazil and still little explored in the world. This work presents patentometry in a theoretical context and its practical application, taking as an example the area of rare earth in Brazil. Analyses will be presented in this work, such as the development of technologies over time and study of the maturity of the sector in question; potential markets; the most significant technology developers in the field; technological sectors related to rare earth in Brazil; attractiveness of the Brazilian market; the evolution of priority sectors; technological specialization; patent quality indices and innovation indices; indexes of technologies internationalization and cooperation. It is expected that with the Patentometry, some of the barriers of insertion in the market of new technologies will be better known and minimized.