Resumo em Português:

Aqueous Two Phase Systems (ATPS) composed of 2-propanol + inorganic salt (Na2SO4/MgSO4) + water, at different temperatures T = (20, 30, 40 and 50) °C were applied in the partition studies of the textile dyes Yellow, Blue Royal and Red Dianix CC. The thermodynamic parameters of the free transfer energy (∆Gtr), enthalpy (∆Htr) and entropy (∆Str), respectively, were determined for dye partitioning, using the Van’t Hoff equation. The values of the partition coefficients of textile dyes Yellow, Royal Blue and Red Dianix CC, ranged from 14.21 to 1610.00, 15.15 to 994.00 and 17.32 to 311.75, respectively; and with dye extraction yields ranging from 93.17 to 99.93; 94.53 to 99.89 and 97.19 to 99.64, respectively. Based on the ∆Gtr results, it was verified that the dyes partition process was thermodynamically spontaneous, in all evaluated systems. For the 2-propanol + sodium sulfate ATPS, there was a prevalence of the enthalpic contribution over the entropic contribution (∆Htr > ∆Str), while for the 2-propanol + magnesium sulfate systems, a greater predominance of the entropic contribution was observed (∆Htr < ∆Str). The recovery yields (Y) values obtained were above 90% for all systems.

Resumo em Português:

The formation of solid waste is a global challenge regarding environmental preservation. Due to the lifestyle of modern society, which aims to improve practicality, new products are constantly being released in the market and increasing the formation of waste. The decomposition of waste from various origins produces a dark liquid named leachate, which presents high rates of organic and inorganic compounds. The objective of this study was to assess the concentration of potentially toxic metals in the leachate collected from the Aurá dump. The concentrations of Cd, Cu, Cr, Mn, Ni, Pb, and Zn were evaluated in leachate samples collected in a period of a year, covering two typical seasonal periods of the Amazon region with more and less rainfall. The leachate samples collected in the Aurá dump were determined in the Toxicology Laboratory of Instituto Evandro Chagas (IEC), by means of Plasma/Inductively Coupled Optical Emission Spectrometry (ICP-OES). The Cr, Mn, and Pb metals analyzed in the slurry samples are in a concentration above the maximum limits specified by CONAMA Resolution No. 430/2011, causing significant environmental concerns.

Resumo em Português:

Biodiesel is a renewable fuel produced from vegetable oils and animal fats transesterification. However, due to its chemical characteristics, it is susceptible to oxidation causing losses to its manufacturers and users. In this work a series of salicylates were synthesized and employed as secondary antioxidants in biodiesel B100. The accelerated oxidation tests were carried out against copper and iron. The biodiesel oxidation degree was followed by the acidity index. Among the synthesized compounds, isopropyl salicylate was able to inhibit the oxidation process by 55% when induced by copper and 52% when it was induced by iron after 8 hours exposure. The commercial antioxidant TBHQ was used as a positive control presenting lower inhibition values than isopropyl salicylate. It should be noted that salicylates are accessible molecules in just one reaction step, high yields and low cost, these being desirable characteristics for the biodiesel industry.

Resumo em Inglês:

This research is the synthesis of urethane prepolymer cast elastomer which had been produced using toluene diisocyanate and castor oil to replace the synthetic polyol, from petroleum origin, and the evaluation of mechanical properties of the polyurethane. The focus was to replace polyol from petroleum to vegetable material looking for renewable resources. The reactions occurred in a pilot reactor considering the process temperature of 70 °C and 0.5 bar of pressure. After the reactions, all prepolymers reacted with the chain extender to cast in sheet molds for mechanical properties. The chains extenders chosen to react with the prepolymers were 4,4’-methylenebis(2-chloroaniline) and castor oil. The better results achieved 65 Shore A as hardness, 35% as rebound resilience, 36.22 mm3 as abrasion resistance, 570.12 psi as tensile strength, 325.39% as elongation and 29.53 kN m-1 as tear resistance; achieved using a blend between castor oil and polytetramethylene ether glycol with 2000 g mol-1 as molecular weight. Thought the mechanical results tests, the castor oil can replace the synthetic polyol depending on applications which did not require a high tensile strength and tear resistance, such as rolls for graphics and cellulose processes, billets seals, cushions and general parts used for industrial segment.

Resumo em Inglês:

The presence of bioaccessible potentially-toxic elements in five different brands of temporary tattoos (packaged with bubble gums) aimed at children and three product brands used by young and adult audiences were analyzed in accordance with the Brazilian Organization of Technical Standards (ABNT) and International Organization for Standardization (ISO) for toy’s safety standards. Bioaccessible barium, copper and strontium were found in the concentration range between 1.78-11.1 μg g-1, 0.0364-0.875 μg g-1, 0.155-9.9 μg g-1, respectively. Bioaccessible lead (2.6 ± 0.1 μg g-1 - 4.36 ± 0.06 μg g-1) and boron (2.14 ± 0.07 - 3.54 ± 0.07 μg g-1) were found in two samples whereas chromium (0.403 ± 0.004 μg g-1) in one sample aimed at children. Bioaccessible aluminum was found in six samples, mostly at products used by children. Other elements whose bioaccessibility was evaluated were Mo (< LOD), Cd (< LOD), V (0.148 ± 0.003 μg g-1) and Co (0.003 - 1.756 μg g-1). All samples met the upper limits permitted by the national toy safety standard, however, chromium, lead, cobalt and barium presented higher bioaccessibility levels than the allowed values by cosmetic regulation that controls products applied directly to the skin.

Resumo em Português:

Air pollution can cause several negative impacts on health and the environment. In large urban centers, this pollution is directly related to anthropogenic activities, mainly activities in the transportation sector. This study analyzed data on black carbon, fine particulate material (PM2.5) and its main trace elements from automotive vehicles (S, P, K, V, Cr, Fe, Cu, Ni, Zn, Cd, Br and Pb), collected during a long sampling period, carried out in the Metropolitan Area of São Paulo (MASP), Brazil. The filters used were analyzed by various analytical techniques, enabling the identification of the different elements present in the samples, their respective concentrations and the main sources of these pollutants and their contributions to the sampled total. Thus, it was possible to separate the total contributions of each source and use only the contributions of anthropogenic origin to define the emission factors (EF) and the crustal enrichment factors (EFc) for the different studied pollutants. We used these factors to compare different environments/studies. We chose two studies carried out previously, also in the MASP, in the Jânio Quadros (TJQ) and Rodoanel (TRA) tunnels, and found that these tunnels are respectively 2.3 and 3.8 times more polluted than the region from our study.

Resumo em Português:

Eugenia uniflora, popularly known as pitanga, is a native species of the Brazilian flora, widely used in folk medicine for the treatment of various diseases and which has several bioactive chemical constituents. The aim of this work was to analyze the chemical composition of flowers visited by bees from Eugenia uniflora by Ultra-Performance Liquid Chromatography coupled with a Diode Array Detector and quadrupole Time of Flight Mass Spectrometry (UPLC-DAD-qTOF-MS/MS). Forty-four compounds were tentatively identified, including quinic acid, seven tannins and thirty-six flavonoids.

Resumo em Português:

Phytochemical study of the roots of Euphorbia phosphorea Mart. (Euphorbiaceae) was carried out through chromatographic techniques, resulting in the isolation of a new ent-abietane diterpene named 11β,12β-dihydroxy-ent-abieta-8(14),13(15)-dien-16,12α-olide (1), and of nine known ent-abietane diterpenes jolkinolide A (2), jolkinolide E (3), euphorin H (4), euphopilolide (5) jolkinolide F (6), ent-12-hydroxy-12[R]-abieta-8(14),13(15)-dien-16,12-olide (7), ent-11α-hydroxyabieta-8(14),13(15)-dien-16,12α-olide (8), 17-hydroxyjolkinolide B (9) and caudicifolin (10). The structures of all compounds were established using spectroscopic techniques such as 1D and 2D NMR, and the structure of the compound 1 was established also with MS, IR and ECD. All compounds were submitted to an in silico study through of a predictive model and then submitted to in vitro tests against Mycobacterium tuberculosis and M. smegmatis for evaluation of their antimycobacterial activity. Compounds 5 and 9 showed mycobacterial growth inhibition with MIC values of 62.5 μM against M. tuberculosis and M. smegmatis, respectively.

Resumo em Português:

Molecular biomarkers correspond to all endogenous or exogenous biomolecules, whose presence or alteration in metabolic pathways indicate the response of a biological system to a disturbance caused by internal or external factors. The search for biomarkers has allowed deepening the knowledge of complex pathophysiological mechanisms of diseases, interactions with potential drugs, and the improvement of diagnostic and therapeutic tests, establishing itself as a central point in personalized medicine. In addition, the development of the omics sciences has fostered an increasing exploration in this field of research. This review presents essential and relevant concepts in biomarker research, explores the various definitions and classifications of biomarkers according to their purpose, the critical aspects to be considered in experimental design, the primary employed study models (in vivo, in vitro, and in silico) and the factors that have hindered their ultimate implementation. Finally, important, and current clinical and pharmacological research areas in which biomarker research play a central role are presented.

Resumo em Português:

Bicyclo[2.2.1]hepta-2,5-diene or norbornadiene (NBD) is a bicyclic hydrocarbon molecule used in many fields of chemistry since its first synthesis in 1950. NBD is the precursor of Aldrin, an agrochemical that was commonly used as an insecticide until the end of the XX century. Norbornadiene is capable of interconverting into its isomer, quadricyclane (QC), by the incidence of ultraviolet light. After that, the QC can release heat to return to the initial stage of NBD. To increase the energy efficiency and to enable the reaction to occur at the solar light, chemists have synthesized a wide variety of NBD derivatives. Papers in more than seventy years have studied and reported the physical and chemical properties of those compounds and their applications as rocket fuel, solar energy cell, homogeneous catalysis, and agrochemicals published between 1950 and 2021. Even computational chemistry has been used to investigate the NBD derivatives synthetic routes, elucidation, and application. In addition, this review describes other applications of norbornadiene.

Resumo em Português:

The wide application of beneficial microorganisms in agriculture as inoculants to combat pests and diseases and/or to improve soil fertility and the nutrients availability for plants has been considered as an effective and more sustainable alternative than chemical fertilizers and agricultural defensives. However, it is necessary to examine all processing steps of these bio-based products under a more integrated view including the type of microorganisms and the whole production process in order to reduce dependence on synthetic chemical inputs. Here, recent developments on the production and formulation technologies of microbial inoculants and the main types of inoculants currently applied in agriculture are addressed. The different types of microbial formulations are compared with emphasis on the encapsulation technology. Moreover, the application of biofertilizers in seed coating and a new approach to apply biocomposites as fertilizers are discussed, presenting the main challenges and future perspectives to promote more sustainable agriculture practices.

Resumo em Inglês:

Metabolic disorders, including hyperglycemia, characterize type-2 diabetes. One of the treatment methods used for postprandial hyperglycemia includes using potential therapeutic agents to inhibit α-amylase activity. This study utilized fractional design and the simplex method to optimize in vitro microscale assay inhibition conditions using Miller’s reaction. In addition, the effect of substrate concentration on enzyme activity was analyzed. Enzyme concentration of 0.15 U mL-1 and pre- and post-incubation times of 7.2 and 5.5 min, respectively, in water bath (15.6 min) equipment, were set up for optimized condition for the enzyme activity. Analytical validation was performed based on different international guidelines. Km was found to be 0.38 mg mL-1. Linearity was obtained at the acarbose concentration of 1.5 µg mL-1 and 5 µg mL-1. The IC50 for the positive control was found to be 0.6 µg mL-1. The relative standard deviation and Z value were found to be <4% and >0.93, respectively. Additionally, the optimized assay was applied to extracts from five different plants. Two plant extracts (Zanthoxylum fagara and Chrysactinia mexicana) inhibited α-amylase activity. The optimized and validated method was accurate, precise, and linear.

Resumo em Português:

Temperature is a natural phenomenon that may modify the structure of chemical compounds and hence their properties. We aimed to develop a simple portable system based on the Peltier principle for spectral characterization of compounds with temperature-dependent structure. The device was constructed and adapted to three pieces of equipment: X-ray diffractometer, vibrational spectrophotometer, and electronic spectrophotometer. The device was evaluated by using commercial thermochromatic inks, whose color depends on temperature. The X-ray diffraction results for the ink whose color changed at a transition temperature of 31 oC showed that the peak at 2θ = 21.6o decreased probably due to alterations in the structures of the components underlying the ink color and solvent. The absorption spectra showed reduced absorption, typical of change in color, a property that is inversely proportional to temperature. The device working range varied from 15 to 75 oC, and it was constructed from parts that are easily available in the national market at an affordable price. The device can be adapted to different equipment with distinct configurations regarding the sample compartment.

Resumo em Português:

An experimental and theoretical approach on oxidative metabolism of paracetamol was applied for the pharmaceutical chemistry learning. Classical reactions, functional group identification, structural parameter, and chemical reactivity using frontier orbitals and Fukui index were used explaining the main products between N-acetyl-p-benzosemiquinone (NAPQI) and thiolic compounds. The chemoprotection mechanisms by N-acetyl-cysteine on high dosage of paracetamol are consistent with theoretical and experimental results. The methods also described the relationship between the chemical reactivity of quinone-imine system and the induced-toxicity of paracetamol by Michael reaction. These results can be applied in experimental pharmaceutical chemistry teaching.

Resumo em Português:

The aim of this manuscript was to show the concepts involving data treatment of RGB based image analysis by univariate and multivariate approaches - the latter using Partial Least Squares (PLS) - using as a practical example application the determination of extravirgin olive oil adulteration. Digital images were collected using a device made of LEDs, batteries and a smartphone and results are shown in a tutorial format using Matlab computing environment. The experiment can serve as an example for teaching the subject for undergraduate and graduate students.

Resumo em Português:

This note has the purpose of calling the attention of the chemist to some aspects of the process of translating chemical terms onto the Portuguese language. A quick inspection on the chemistry literature in Portuguese shows a certain number of inadequate or dubious translations of terms originally coined in other languages. Firstly, the possible origins of these inadequacies are briefly discussed. Then one proceeds to a cursory explanation of some fundamental concepts such as signs, words, meaning, real referents, scientific concept, and scientific term. These concepts are traced back to the origin of Western Civilization, being first systematized in the work of Aristotle, forming the backbone of all Western languages. A short discussion on the features of a well-done translation is presented. Finally, a set of ill-translated or dubiously translated or dubiously named chemical terms are used to illustrate the presented concepts, divided among the general type of inadequacy. In some cases, with justification, grammatically correct or more adequate terms are suggested to replace the offending translated chemical terms in portuguese.