Resumo em Português:

MONITORING OF TRIHALOMETHANES (THMs) AND WATER QUALITY FOR PUBLIC SUPPLY IN THE CITY OF CAVALCANTE, GOIÁS. Trihalomethanes (THMs) are organohalogens compounds formed from the reaction between free residual chlorine and natural matter organic (humic substances) present in raw water from surface sources. This study aimed to evaluate the formation of THMs resulting from the application of chlorine for disinfection, in the water treating process for public supply in the city of Cavalcante, GO, located in the region of Chapada dos Veadeiros (Brazil). The results of physical-chemical analyses apparent color, turbidity, pH, free residual chlorine, consumed oxygen, hardness, total alkalinity and THMs demonstrated a positive and strong correlation between the formation of THMs and the hardness of treated water, as well as the chlorine consumed during disinfection process. It was observed an increase in apparent color, turbidity and consumed oxygen in the rainy season. These parameters indicate the presence of organic matter and that present a positive and moderate correlation with the formation of THMs.

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SYNTHESIS, CHARACTERIZATION, ANTIMICROBIAL ACTIVITY OF COPPER FERRITE NANOPARTICLES AND THEIR INCORPORATION IN GLASS IONOMER CEMENT. Pure cubic copper ferrite (c-CuFe2O4), cerium-doped cubic copper ferrite (c-CuCeFe2O4) and pure tetragonal copper ferrite (t-CuFe2O4) nanoparticles were synthesized from the proteic sol-gel method, and characterized by X-ray diffraction, Rietveld method, FT-IR spectroscopy, and field emission scanning electron microscope. The antibacterial activity of the particles was tested in vitro against pathogenic Gram-positive, Gram-negative bacteria. Thus, it has been observed that the nanoparticles are capable of inhibiting the growth of such microorganisms. The nanoparticles were incorporated into glass ionomer cement, followed by Vickers microhardness evaluation. It is concluded that the cubic copper ferrite showed the best antimicrobial result, being the most suitable for market studies (industrial and biomedical).

Resumo em Inglês:

Owing to merging antibiotic resistance, the synthesis of novel antibacterial agents becomes increasingly important. Carbon dots (CDs) belong to a new class of carbon-based nanomaterials that have shown great potential in combating emerging and drug-resistant infections due to their unique optical properties, such as excellent biocompatibility and easy surface modification. Herein, light-treated CDs (LCDs) with enhanced antibacterial activity and low drug resistance were synthesized by using a simple one-pot hydrothermal method. LCDs can generate reactive oxygen species (ROS) under the light-emitting diode light, which kill two pathogenic bacteria, including methicillin-resistant Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). In addition, in vitro experiments show that the liquid crystal displays excellent biocompatibility. Due to the visible photo-oxidative activity, LCDs can be used as photodynamic therapy agents, providing efficient bactericidal activity. This study provides a simple way to modify CDs that lead to new properties.

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SESQUITERPENES ALKALOIDS FROM Maytenus distichophylla (CELASTRACEAE). The phytochemical study of the roots of Maytenus distichophylla Mart. ex Reissek (Celastraceae), resulted in the isolation of the seven sesquiterpenes pyridine alkaloids euojaponine F (1), euojaponine K (2), ebinifoline W-I (3), wilforine (4), maiteine (5), euojaponine A (6) and ebinifoline E-II (7). The structures of compounds were established using spectroscopic techniques such as 1D and 2D NMR. All compounds were subjected to an in silico study through of a predictive model and then submitted to in vitro testing against S. epidermidis, P. aeruginosa, C. parapsilosis and C. albicans for evaluation of their antimicrobial activity. The compounds tested showed bacterial and fungal growth inhibition with MIC values 1024 and 256 µg mL-1, respectively.

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Hydroxyurea (HU), also known as hydroxycarbamide, is an effective anticancer drug. The present work is based on partially cross-linked chitosan with glutaraldehyde in the presence of hydroxyurea. The obtained embedded HU in the cross-linked matrix was evaluated as a controlled-release drug based on the swelling mechanism. The swelling study was carried out in simulated gastric fluid (SGF), simulated intestinal fluid (SIF), and deionised water. The % of swelling at equilibrium for the 0.25% crosslinking density after 24 h of immersion was: 200, 150, and 100% in SGF, H2O and SIF medium, respectively. The concentration of the released drug HU from the chitosan matrix in the different media was determined by UV spectroscopy at λmax at 208.5 nm as a function of time. The release rate of HU from the matrix increases with the swelling rate of the partially cross-linked chitosan. The loading capacity of the prepared gel was 33.3% by weight. The loading capacity and the rate of HU release were found to be inversely affected by the high degrees of crosslinking and increased with increasing the degree of hydrogel swelling. In addition, the rate of HU release was higher at lower pH levels. The study showed that the HU released from the hydrogel matrices in SGF reached 75 and 88.3% of the loaded HU within 8 and 24 h, respectively. This is almost twice the reported value in the literature based on polyphosphate-anion-cross-linked chitosan microspheres.

Resumo em Português:

This study evaluated the impact of in silico simulated gastrointestinal digestion (GID) of four quinoa globulins on the potential to release ACE and DPP-IV inhibitor peptides (antihypertensive and antidiabetic properties, respectively), as well as performed a molecular docking study to evaluate the interactions produced in the peptide-enzyme complexes. In silico GID performed on quinoa globulins resulted in the formation of amino acids as well as peptides with two to five residues. The peptides PSF, IPG, CSG, SPR, CSPG and PPN stood out for their high bioactivity scores (> 0.6), for not showing toxicity, as well as presenting potential inhibitory properties to both ACE and DPP-IV enzymes evaluated by ToxinPred, PeptideRanker and BioPep tools, respectively. The molecular docking analysis allowed highlighting that all peptides interacted with the enzymes, finding favorable binding energy values, different number and type of interactions, either at the level of the enzyme active sites or not, characteristics that together would define the potential of the established interaction of the complexes formed. The results, at the level of a first screening, support that GID of quinoa globulins can give rise to peptides with both antihypertensive and antidiabetic properties, requiring further in vitro and in vivo studies.

Resumo em Português:

With the increasing drilling depth, problems follow, such as the lifting height of the liquid in the well and increased pump operation. Therefore, improving the production efficiency of deep wells is a hot spot in the current oil drilling and production industry. This paper designs a new jet pump that can be mined for high and low-pressure oil layers according to the oil wells’ inter-layer contradiction. The FLUENT software is used to simulate the new jet pump, analyze the pump efficiency factors of the jet pump and the physical properties of the fluid, and the BP neural network is used to optimize the structure of the jet pump. The results show that the maximum pump efficiency of spout distance, duct diameter, duct distance, and spread angle is 2.61-5.22 mm, 6.393-8 mm, 42.5-53.2 mm, and 6-9°, respectively. The best spout distance, duct diameter, duct distance, and spread angle are 2.74 mm, 6.80 mm, 46.5 mm, and 7.4°after being optimized by the BP neural network model presented in this paper and the optimized pump efficiency is improved by 9.45%.

Resumo em Português:

A NEW ERA OF INCORPORATION OF FLUORINE ATOM ON ORGANIC COMPOUNDS: MODERN METHODS AND USE OF 19F MAGNETIC RESONANCE SPECTROSCOPY. During the last decades, the incorporation of the fluorine atom in organic molecules suffered an increase, mainly in the pharmaceutical and agrochemical industries, due to the unique properties of the fluorine atom and the desired behaviour of the molecules resulting from fluorination processes. We present the rise and historical evolution of both fluorination agents, nucleophilic and electrophilic agents, and the three fluorination conditions, nucleophilic, electrophilic and neutral (radical) conditions. The advantages and disadvantages of each type of fluorination agent and condition are highlighted employing modern methods of fluorination, along with the presentation of the author’s mechanistic proposals and discussion of the scope of the reaction. Green chemistry, more sustainable procedures and the use of alternative methods are gaining more attention and are the challenges of the fluorination of organic compounds. 19F NMR technique is also highlighted as a powerful tool for structural elucidation, intermediates identification and reaction monitoring. 1D and 2D NMR experiments involving fluorine are widely employed in biological areas and need to be more widespread in organic synthesis to help face the challenges of this area.

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TEACHERS’ PERCEPTIONS ABOUT THE USE OF THE PROBLEM-SOLVING METHODOLOGY FOR INCLUSIVE EDUCATION IN THE TEACHING OF CHEMISTRY AND SCIENCE. This manuscript aims to present and analyze the contributions of a training process on the principles of Inclusive Education integrated with the Problem-Solving (PS) methodology. This research intervention involved a 20-hour training course conducted during three consecutive semesters, with a total of 32 participants, including graduates in Chemistry and Biological Sciences from a Brazilian federal public university, as well as Chemistry and Biology teachers working in basic education in Rio Grande do Sul. Data were collected using initial and final procedures, field diary entries, and semi-structured interviews with three participants who implemented PS in a school context. According to the triangulated results, the formative action contributed to the conceptual construction of the theoretical aspects that were worked on. It also demonstrated that PS can democratize the teaching and learning process among students with and without disabilities by considering the different possibilities of learning school problems and representations of scientific knowledge. The methodology favors respect for the students’ developmental specificities, as well as educational interaction and mediation in an active and collaborative way between students and teachers.

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USE OF ARROWS IN THE CONTEXT OF LEARNING IN CHEMISTRY AND THE IMPORTANCE OF ITS SYMBOLISM. The representation of arrows in Chemistry learning is routinely applied in classrooms and textbooks. Arrows of different shapes like horizontal, curved, vertical, or wavy have been used as symbols since the beginning of ancient civilizations, representing elements or compounds. The arrow is one of the most used symbols in Chemistry, as different types have presented different functions, especially in chemical reactions, and because there is no consensus, their use has generated ambiguities and confusion when applying them. In this sense, the present work sought to present and differentiate the types of arrows used in Chemistry to provide a better understanding of this symbol in the learning process. Furthermore, a historical overview of the emergence of arrows in the world of chemistry and the process of acceptance as chemical symbolism in chemical reactions is provided. The use of arrows in some chemical phenomena (e.g., resonance, tautomerism, symmetry operations, and movement of electrons) is also detailed. This work reflects that arrows, as chemical symbolism, require an increasingly concrete standardized notation system to avoid ambiguities of concepts. Finally, when using them, let us consider why the arrow is being symbolized and, above all, what is the scientific concept behind its symbolism.

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CONTRIBUTIONS OF FEDERAL INSTITUTES TO THE DEVELOPMENT OF INITIAL GRADUATION OF CHEMISTRY TEACHERS IN BRAZIL. Federal institutes work in the formation of chemistry teachers, since the implementation of Law 11.892 of 2008, which created the Federal Institutes of Education, Science and Technology. In this study, we sought to know, through data found on the e-MEC and INEP platforms, the vacancies, flow of formation in chemistry and the formation of chemistry teachers in federal institutes and compare their role with public universities from Brazil. In view of the data, it was possible to perceive that the federal institutes offer 30% of the training of chemistry professionals, and 34% of the vacancies in chemistry teacher’s degree. It can still be seen that this advance in vacancies has taken place in the last 14 years. Another point observed was the training flow, in which the number of enrollees was analyzed in relation to the number of graduates over a period of up to 5 years. The data show that federal institutes have an average of 25% of graduates, which is higher than the average of public universities. Thus, we can say that federal institutes play a satisfactory role in the offer of vacancies and in the formation flow, when compared to public universities.

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THE USE OF HIRSHFELD SURFACE ANALYSIS TOOLS IN THE STUDY OF NON-COVALENT BONDS IN RELATED COMPLEXES. The analysis of non-covalent interactions in crystalline structures through the Hirshfeld surface method using the CrystalExplorer® software has been widely used by the global scientific community over the past few decades. Although widely recognized, as far as we know, there has been no publication on this subject in the Química Nova journal. Therefore, in this work, we intended to demonstrate how these tools could be employed to study and compare the non-covalent bonds in 21 mononuclear complexes of the type [MY2(o-XPy)2], [MY2(m-XPy)2], and [MY2(p-XPy)2], where M = Zn2+ or Co2+, Y = Cl−, Br-, or I−; Py = pyridinic ligand ortho-, meta-, or para-monosubstituted by X, where X = Cl−, Br−, or I−. With a main emphasis on halogen bonds and π···π stacking interactions, the study demonstrates how Hirshfeld analysis can be used for a qualitative and quantitative comparison of non-covalent bonds, proving to be an important tool for a comprehensive understanding of the forces that stabilize these complexes in the solid-state. The study demonstrates the potential of Hirshfeld surface analysis as a valuable resource for synthetic chemists to select chemical species for rational synthesis and achieve desired properties or supramolecular arrays.