Resumo em Inglês:

High-yield ZnO spheroidal nanoparticles with an average diameter around 23 nm (≈ 25% frequency) and 30 nm (≈ 28% frequency) were obtained by controlled semicontinuous precipitation at low temperatures. This synthesis was obtained from hydrozincite (Zn5(CO3)2(OH)6) as primary nanoparticles. The Zn5(CO3)2(OH)6 nanoparticles were synthesized by hydrolysis of Zn(NO3)2 in aqueous solution of (NH4)2CO3 and later, the precipitation becomes. Two temperatures of 60 and 70 °C in combination with three times of reaction were tested; followed by calcination of the precipitate at 400 °C. This range of sizes of nanoparticles is comparable with those obtained by other methods reported in the literature, such as microemulsions, however, here the advantage was not using solvents or surfactants. The ZnO nanoparticles were characterized by energy dispersive X-ray spectroscopy coupled to a scanning electron microscopy (SEM-EDS), transmission electronic microscopy (TEM), and X-ray diffraction. The antibacterial activity of the films against Gram-positive (S. aureus) and Gram-negative (E. coli.) bacteria was investigated using the disc diffusion method. The best results were found in the inhibition zone for Gram-positive bacteria, when the concentration of ZnO NPs incorporated was 3 mg disc-1.

Resumo em Português:

In this article the synthesis, characterization, acute toxicity, and antitumor activity of the novel Ru3+ complex are described. Through the acute toxicity tests, it was possible to fit the complexes into categories according to the OECD protocol guideline 423. The cisplatin complex was classified in category 1 and the sodium diaquodimalonateruthenate(3+) - Na[Ru(H2O)2(Mal-κ2O)2] - was classified in category 4. This result demonstrates the lower toxicity achieved by the ruthenium complex in comparison with metallopharmaceuticals compound. Evaluations of tumor masses extracted from mice inoculated with Ehrlich ascites carcinoma demonstrated percent inhibition lowest to cisplatin. Cisplatin showed 58% inhibition (1 mg/kg), while Na[Ru(H2O)2(Mal-κ2O)2] complex (5 mg/kg) presented 77%.

Resumo em Inglês:

The terahertz (THz) absorption spectra of 4- and 5-hydroxysalicylic acid were measured by terahertz time-domain spectroscopy (THz-TDS) in the range of 0.4-2.8 THz. The unit cells of both were calculated by density functional theory (DFT), and the theoretical simulation and experimental data were basically in agreement. To further interpret the origin of the characteristic absorption peaks, vibration characteristics and interactions of the unit cell model were analyzed by using potential energy distribution (PED) and interaction region indicator (IRI) method. The analysis indicated that the absorption peaks of 4- and 5-hydroxysalicylic acid were mainly derived from the vibration mode of dihedral angle torsion, and were closely related to the hydrogen bonds. And the intermolecular weak interaction of both were mainly dominated in quantity by van der Waals interaction. The results show that this is an effective solution to identify isomers and explain the formation mechanism of characteristic absorption peaks by using THz-TDS and combining PED and IRI methods.

Resumo em Português:

In this work, Zn/Al layered double hydroxides intercalated with dodecyl sulfate ion (DS) in molar ratios (Zn2+/Al3+) 2:1, 3:1 and 4:1 were synthesized by co-precipitation method and then they were adsolubilized with essential oil of copaiba in the concentrations of 3, 5, 10, 13 and 15% wt/wt to be used as carriers in therapeutic ointments for skin injury treatments. The XRD results showed a diffraction pattern corresponding to the structure of LDHs with the presence of diffraction peaks referring to the basal reflection planes. Typical stretching and vibration bands of copaiba essential oil in FTIR spectra confirmed the adsolubilization process. The oil release plateau in the ointment was above 80% at normalized values in a time of approximately 20 h, the time required for dissolution and release of molecules adsorbed in the layered structure of the material for molar ratios 2:1 and 3:1 and the release of the solubilized molecules in the interlayer space. In contrast, LDH with a 4:1 molar ratio showed slower release and did not reach the plateau in 48 h, as this material has the ability to retain oil molecules in the LDH for longer, causing a slower release in relation to other molar ratios. The analysis for the non-intercalated copaiba oil showed a gradual increase in the concentration of the oil in the ointment, indicating a different curve profile.

Resumo em Português:

In this paper, the piperine (PIP) and eugenol (EUG) organic compounds were used as substrates in olefin metathesis reactions catalyzed by first-generation Grubbs catalyst (G1) - [RuCl2(PCy3)2(=CHPh)], Cy is cyclohexyl and Ph is phenyl, in a one-pot system. The reactions occurred at 50 ºC, for 24, 48, or 96 h using the two substrates simultaneously in the ratio Ru:PIP:EUG of 1:1:1 and 1:10:10 mol. The results were evaluated by GC-MS, discussed in terms of the electronic and steric characteristics of the G1, and the structural proprieties of the substrates. In the Ru:PIP:EUG ratio of 1:1:1 mol, a dimeric species was observed for the olefin metathesis of EUG, in all time studied and in an additional experiment at 70 ºC for 48 h. When the Ru:PIP:EUG ratio was 1:10:10 mol, this dimer was not observed. Isomerization processes also were observed at all temperatures and catalyst:substrates ratio. The reaction yield increased with the raise of substrates amount. There was no cross-metathesis reaction. This fact was attributed to the chelating effect of the double coordination of the PIP to the catalyst.

Resumo em Inglês:

Biodiesel is capable of replacing diesel because it has similar physicochemical properties, but this biofuel is susceptible to oxidation, which makes the application of antioxidant substances necessary. For this study, alcoholic extracts of senna leaves, hibiscus flowers, and blackberry were used. Biodiesel samples were submitted to physicochemical analysis to evaluate interference in the volume of these alcoholic extracts with antioxidant properties. The data obtained were processed using the neural network of the multilayer perceptron type (MLP). For the network’s training, 200 epochs were used. The samples were randomly divided into three groups, with 70% used for training, 15% for testing, and 15% for validation. The type of extract was considered as a categorical variable, the extract volume as a target variable, and the other ones as input variables. Among the 200 networks trained, with 5 to 20 hidden layers, the 5 with the best performance were highlighted. The Tukey test applied to the means showed no significant difference at the 5% level, between the value of the added volume and the means value predicted by the networks. The sensitive analysis showed that the most important input variable for the construction of the model was the type of extract.

Resumo em Inglês:

NaCMC is a biocompatible polymer that can be crosslinked with citric acid to form a gel matrix. Melaleuca oils have antimicrobial and anti-inflammatory properties with potential for wound healing. The goal of this work was to investigate the characteristics of NaCMC-Melaleuca oils gels. The gels were characterized by FTIR, TGA, mechanical analysis, and in vitro swelling and S. aureus inhibition tests. The oils were characterized using chromatography, presenting high values of (1,8-cineol/terpinen-4-ol), and evaluated for confirmation of their effect against S. aureus. The samples showed physical interactions between NaCMC, citric acid and the Melaleuca oils. Erosion in saline solution was higher in the gels with oils, attributable to interference with crosslinking. The membranes presented high contribution of relaxation mechanism and low contribution of Fickian diffusion regarding the swelling ability. The presence of the oils increased thermal stability and diminished gel fraction and mechanical properties, indicating that the oils interact with the matrix anchoring the chains. Although melaleuca oils themselves were active against S. aureus and CA was responsible for the NaCMC hydrogels activity, the incorporation of melaleuca oils in NaCMC gels was not reported previously. This report indicates that NaCMC hydrogel may be a proper matrix for essential oils incorporation.

Resumo em Português:

The international trade of essential oils accounted for more than US$ 10 billion in 2021, with a growing tendence. USA, China, India, France and Brazil are the main global players. Reliable and comprehensive market data, however, is hard to obtain. Apart from a few government databases dealing with import/export values, information regarding local (national/internal) production and consumption as well as market trends, when available, are for sale, and expensive. Data from the global and Brazilian markets in the last decade were gathered and discussed in this review, with highlights on the balance of trade and the main oils produced in Brazil. As a megadiverse country, opportunities for new essential oils from Brazil do exist, but several obstacles must be overcome, such as legislation compliance, quality, supply and safety assurance, so that the market can be conquered.

Resumo em Português:

The presence of N-nitrosamines - potentially carcinogenic compounds - is being reported for more than 50 years in pharmaceutical products. However, it only gained notorious prominence in 2018, when regulatory agencies became aware of the presence of N-nitrosodimethylamine in angiotensin II receptor antagonists, drugs that are known as sartans. It did not take long for N-nitrosamine impurities to be identified in other medicines, alerting government agencies and pharmaceutical industries to evaluate and control these impurities in their products to mitigate the risk. The sources of contamination can be numerous, including the use of contaminated raw material, formation in the synthesis of active pharmaceutical ingredients or during storage, the water used in the process, and the packaging material. This review article presents the timeline of the presence of N-nitrosamines in consuming products, toxicological aspects, legislation, and analytical methods. It provides relevant information on possible sources of contamination in the production and storage process that may explain the presence of these compounds considered a cohort of concern in pharmaceuticals.

Resumo em Inglês:

Pavonia Cav., is a genus in the Malvaceae sensu lato family, containing 271 species with worldwide distribution, although with a higher diversity in America and Asia. Species from this genus are traditionally used in folk medicine with several biological activities, arousing scientific interest on the search for the substances responsible for such activities. This review aimed to provide and expand the scientific interest through phytochemical and pharmacological studies and the utilization of those plants in folk medicine. Species P. odorata and P. zeylanica are described in literature, specially at India, following the traditional medicine system Ayuverda, while the other species are studied mostly at Africa and America. There have been around 169 compounds isolated and characterized for such genus, most of them from the metabolic classes fat acids, terpenoids, flavonoids and phenolic compounds. Those species have shown in vivo, in vitro and in silico significant pharmacological activities, which include anti-inflammatory, analgesic, antimicrobial, cytotoxic, antitumoral, antidiabetic and antioxidant properties. Based on those informations, the search for new sources of plant based biologic prototypes with potential for the treatment of several diseases is of major scientific, economical and medicinal interest.

Resumo em Português:

Although analytical techniques to assess the degradation of transformer insulation systems are well established, it is essential to develop fast and effective methodologies for monitoring the quality of power transformer insulating fluid. The objective of this work was to develop a fast, simple, and environmentally friendly method to evaluate and monitor the quality of insulating vegetable oil (IVO) from transformers, using multivariate control chart and infrared spectroscopy (FTIR). For the development of the method, IVO samples were subjected to electrical and thermal stress, as well as to contact with insulating paper and copper, to simulate the internal environment of a transformer before and after energizing. Control chart based on principal component analysis was developed to monitor insulating vegetable oil quality. It was possible to identify oil samples with oxidation levels that were outside the acceptable quality standards for insulating fluid in transformers. The results demonstrated the potential of FTIR spectroscopy and control charts as fast and simple tools for monitoring the quality of insulating fluids, enabling the identification of oil samples that fail to comply with regulation standards for insulating fluids, assisting in the implementation of maintenance programs for power transformers.

Resumo em Inglês:

This work describes a simple, sensible, and low-cost analytical method, based on cloud-point extraction (CPE) of the surfactant (1,1,3,3-Tetramethylbutyl)phenyl-polyethylene glycol (Triton X-114), for the efficient extraction and sensible determination of gadolinium after its complexation with 1-(2-pyridylazo)-2-naphthol (PAN) and subsequent determination by ultraviolet-visible molecular absorption spectrophotometry at the wavelength of 556 nm. Full two-level and Doehlert experimental designs were applied to investigate and optimize the variables (pH, complexing concentration, and TX-114 concentration) involved in the extraction efficiency of Gd3+. The CPE was satisfactory for the determination of gadolinium with limits of detection (LoD) and quantification (LoQ) of 1.0 and 3.2 µg L-1, respectively, as well as an enrichment factor of 9.4. Accuracy was confirmed by spike tests with recovery values between 98.4 and 78.3%. The precision was expressed as relative standard deviation (%RSD, n =3), being found: 2.3% (10 µg L-1) and 2.7% (100 µg L-1). The proposed analytical method is suitable for the determination of Gd in tap water and contrast agent solutions.

Resumo em Português:

Green and Sustainable Chemistry (GSC) provides scientific and ethical innovations to achieve a sustainable future. In this context, international efforts and strategies have been made to incorporate this green philosophy into education. Brazil has immense potential to lead in this scenario, providing new approaches to introduce GSC into secondary education, especially with 2022 being the International Year of Basic Sciences for Sustainable Development. However, most published works on GSC are in English, which can be a language barrier for implementing GSC into Portuguese-speaking communities, such as Brazil. From this perspective, this paper aims to present a translation of the “Periodic Table of the Elements of Green and Sustainable Chemistry” by Paul T. Anastas and Julie B. Zimmerman into the Portuguese language. Our systematic translation of the names of the elements into Portuguese followed rigorous semantic and contextual details required for this process. We also identified and recommended some teaching opportunities of this interdisciplinary encyclopedia in alignment with a sustainable future. This green periodic table is a multidisciplinary tool that provides directions for “Systems Thinking in Chemistry Education”. Therefore, we contributed to the standardization and greater discussion of this alternative periodic table for future Portuguese-language publications.

Resumo em Português:

Students, generally, are afraid of studying chemistry because they understand that it is a very complex area of knowledge and that it doesn’t has use in daily lives and in intended profession, which is a problem we identified in a Civil Engineering course. With this, we proposed a project in this course, based on educational robotics and educational cooperation, with the intention to form a group of students and a teacher to make a robot involving chemical knowledge in civil construction. The group made a robot, using an Arduino kit and material recycling, to identify electrochemical corrosion in concrete structures. We conducted a case study about the group through the analysis of gestures, products made, and notes in a notebook, from which two cooperative categories emerged: planning and application. From these categories, we identified that the students had their cognitive structures unbalanced by difficult situations, trials, errors, and diverse knowledge. The formation of a new equilibrium condition resulted from individual and social developments in constant interdependence, allowing the joint construction of knowledge, whose complexity increased during the process and culminated in the realization of the robot. All these aspects characterized cooperative learning.

Resumo em Inglês:

Flavonoids are metabolites occurring in all plant tissues and present different biological activities. They occur in a mixture of similar polarity with laborious separation and purification processes, usually furnishing low yields. Semi-preparative chromatographic methods are universally employed procedures for their isolation. This paper discusses the state-of-the-art in new non-chromatographic techniques for the separation and purification of flavonoids. In the last decades, novel methods for flavonoids purification have been developed to decrease time extraction, reduction of costs, and organic solvent. Herein, we present the state-of-the-art development of ionic liquids, eutectic solvents, chelating agents, and molecular imprinted polymers in greener extractions, enrichments, and the purification of flavonoids. As the main advantage, these proceedings permitted good yields of bioactive flavonoids and biflavonoids, and they are improved when ultrasound, microwave, and mechanical extractors are used in the extraction step. Nevertheless, most of these techniques are not specific to a single molecule’s purification, except MIPs mainly used for analytical purposes. These examples indicate that the development of efficient and straightforward methods for the obtention of different bioactive flavonoids is still incipient but with potential for discovering specific and greener procedures for isolating the target compounds in good yields.