The generation of mathematical models through the quantitative relationship between the chemical structure and the biological activity (QSARs) of compounds was used in this investigation. Mathematical models were generated from compounds available in literature that predicting the biological activity against SARS-CoV-2. The data indicate that the parameters that most interfere...
The beneficial effects of humic substances (HS) on crop development have been evidenced in the last decade, leading to the commercialization of HS products with fertilizing properties. Currently, three methods are frequently used for HS determination: method described in the manual of the Brazilian Ministry of Agriculture, Livestock and Supply (MAPA); method employed by the...
Much is said and written regarding alchemy all across the world, in what could be called a renaissance of alchemical studies. However, relatively little is done in terms of actual alchemical laboratory work. The aim of the project described herein was to show how crucial the development of technical alchemical practice was along the centuries, in the discovery of an immense...
In recent years, much has been said about the approach of the history of science and science teaching. We know that this approach can be made using historical episodes in science classes. In this sense, this work aims to bring a historical episode to be worked on in general chemistry classes in high school, as well as in general chemistry classes 1 of university courses. Thus, we...
Multicomponent reactions are attractive for the development of bioactive substances, being a one-pot synthesis allows a quick and efficient synthesis, and allows the construction of a diversity of privileged structures. The Debus-Radziszewski reaction, a classic example of a multicomponent reaction for obtaining 2,4,5-tri-substituted imidazole, was used to compose a didactic...
Research in the area of science teaching has highlighted the importance of using argumentation in the classroom, as well as preparing teachers to undertake and conduct activities of this nature. In order to bring elements that contribute to the progress of discussions about the subject, we investigated implementing and developing two teaching strategies (ludic activities and...
Medicines are employed in undergraduate courses as motivational strategy. The experiment herein developed compares the extraction of paracetamol from generic and brand name drugs. Tablets were used from two commercial sources purchased from local drugstores. Twenty tablets of each drug type were individually weighed to average weight analysis and mass dispersion was statistically...
The ultrasound-assisted extraction (UAE) is an alternative approach for the total lipid content determination in food samples. The high extraction efficiency, being less time-consuming and with the possibility of using less toxic solvents are the main advantages of UAE. It is, thus, an excellent alternative to be applied as a laboratory experiment for undergraduate students. The...
Plants from Fabaceae family have several secondary metabolites and high biological potential. The subfamily Papilionoideae (Fabaceae) has 28 tribes, of which Dalbergieae comprises 49 genera and 1325 species. Isoflavonoids are chemotaxonomic markers of Papilionoideae and have important biological properties. This review describes the isoflavonoids and biological activities from...
The foods enrichment with essential elements is an alternative to supply deficiencies of micronutrients and the fortification by rich cultivation is a promising strategy for the elemental enrichment of agricultural origin products, mainly in regions where there is high prevalence. On the other hand, in elemental enrichment procedures, possible antagonistic and / or synergistic...
Recently, a new class of materials, the Perovskite Nanocrystals, also known as perovskite quantum dots (PQDs) has emerged. Perovskite nanocrystals are promising in optoelectronics due to their quantum confinement properties, narrow photoluminescence bands with short decay times, optically tunable bandgaps, easy surface passivation and high photoluminescent quantum yields. The...
The generation of mathematical models through the quantitative relationship between the chemical structure and the biological activity (QSARs) of compounds was used in this investigation. Mathematical models were generated from compounds available in literature that predicting the biological activity against SARS-CoV-2. The data indicate that the parameters that most interfere...
Chitosan is a biopolymer derived from chitin and the most abundant polysaccharide in nature after cellulose. This biopolymer has been applied in different areas due its biodegradability and biocompatibility properties. Modifications of chitosan structure by cross-linking chemical agents can alter its physical, chemical, and morphological characteristics. The present work aimed at...
Biodiesel made from oils is rich in polyunsaturated fatty acids methyl esters, and, consequently, presents high tendency to oxidize. Biodiesel made from fats, on the other hand, is mainly comprised by saturated chains. Although it is highly stable, they easily crystalize at low temperatures. Blends from both can exhibit optimized properties. In this work, oxidative stability...
The analysis of volatiles is an alternative in the routine of quality control of fruits, since the volatile metabolites can change in the presence of microorganisms. A well-established method for extracting volatiles is the solid phase microextraction (SPME). This work aims to define some parameters (fiber coating, conditioning time and fiber exposure time) for an effective...
The lipase from Rhizomucor miehei (RML) has been immobilized on chitosan-based hybrid (sodium alginate or carrageenan) matrices activated with glycidol (GLY), epichlorohydrin (EPI) or glutaraldehyde (GLU) groups. Then, the properties of the different biocatalysts have been evaluated and compared with the soluble RML. Thermal stability (at pH 7.0 and 60 °C) was significantly...
The volatile compounds present in cachaça can derive from the raw material used in the production of the beverage, from the fermentative process, from distillation or aging. The aim of the research was to evaluate the volatile compounds, in the cachaças from stills produced with different sugarcane varieties, under the organic and conventional managements. The varieties RB867515...
The surface intermediates formed on the Mg-La catalyst (molar ratio 1:1) were studied through temperature-programmed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy coupled to mass spectrometry (DRIFTS-MS) using methanol (MeOH) and ethyl acetate (EA) as probe molecules. TPD results showed that the products formed from adsorbed MeOH were hydrogen...
This work describes the chemical composition of MeOH seeds and flowers extracts of Tapirira guianensis, a known tree that occurs in the Brazilian Atlantic forest. The CH2Cl2 soluble fraction of seeds extract was submitted to chromatographic procedures to obtain a mixture of new alkenyl dihydrobenzofuranoids which were identified as 2-[(10’Z)-dodec-10’-enyl]-dihydro-1-benzofuran-5...
Biodiesel contains unsaturated methyl esters making it susceptible to oxidation reaction. Among the factors that cause oxidative instability is the contamination by transition metal ions that in small quantities catalyze the oxidation reaction. The objective of this work was to evaluate the relative protection factor of rosemary extract, in biodiesel, in the presence of...
A new spectrophotometric method was developed for the determination of taurine using 7,7,8,8-tetracyanoquinodimethane (TCNQ). The method was based on the formation of charge transfer (CT) complex of this drug as n-electron donor with the π-acceptor TCNQ. TCNQ was found to react with taurine to produce a kind of yellow complex. The spectrum obtained for taurine/TCNQ system showed...
Analytical validation has fundamental importance in the scope of Good Manufacturing Practice (GMP) for pharmaceutical products since it establishes scientific evidence that an analytical procedure provides reliable results. However, even with validation guidelines available it is very common to observe misunderstandings in the execution of validation and data interpretation. The...
During the last 150 years or more, society has witnessed many key scientific discoveries and inventions, which have dramatically improved not only our quality of life, but our lifespan. However, the motivation of scientists to provide scientific advances has generally not been the achievement of these goals, but mainly driven by research curiosity. Fundamental scientific studies...
A short experimental activity aimed at upper level undergraduate students or beginner researchers is presented to introduce the concepts of edge effects and hemispherical diffusion at ultramicroelectrodes. Students will perform simple cyclic voltammetry experiments varying the scan rate and using disk electrodes with different radii. They are then asked to interpret the results...
Although the impacts of science discoveries are relevant to society, awareness of this intellectual output is still minimal. Much of this communicative failure between researchers and the general public lies in the disclosure, which contributes to the superficiality and misinterpretations of the content served. Strategies need to be found to improve science communication...