Resumo em Inglês:

High-density polyethylene (HDPE) geomembranes are commonly used as an environmental protection liner due to their good chemical and mechanical resistances and low cost. Ultraviolet (UV) radiation is an essential issue in durability studies for pond applications. This study evaluated a 1.5-mm thick HDPE geomembrane exposed to ultraviolet fluorescent radiation for 8760 h in a laboratory and thermoanalytical and physical analyses were conducted towards the understanding of its performance after exposure. According to the results, although the geomembrane maintained the ductile behavior, it showed a 52.48% final decrease in stress crack resistance (SCR) compared to virgin SCR. Moreover, a considerable antioxidant depletion occurred after 8760 h exposure shown by the Std. OIT (standard oxidative-induction time) results, demonstrating a Std. OIT value decrease of 89.19% compared to the virgin Std. OIT. Such a behavior contributed to the susceptibility of thermal effects in the DSC (differential scanning calorimetry) curves and the losses observed in the SCR values, attesting the geomembrane’s oxidative degradation mechanism occurred and changed the polymer’s structure.

Resumo em Inglês:

Protium ovatum Eng. Burseraceae is an endemic species in Brazil used in traditional medicine. This study investigated the chemical variation and the in vitro antioxidant and antimicrobial properties of dichloromethane soluble fraction of hydrolate (DSFH) from leaves of P. ovatum collected from five different vegetation physiognomies within the Cerrado Goiano. The region was characterized based on the DSFH chemical composition by gas chromatography coupled to mass spectrometry (GC-MS) analysis. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were performed to compare the different DSFHs from five Savannah regions in Brazil. The DSFHs from the Cerrado stricto sensu (CSS), Mata de Galeria (MG) and Cerradão (C) regions were grouped in the negative part of PC1, showing high similarity. Samples from the C and MG regions showed antioxidant activity of IC50 = 0.98 and 0.78 mg mL-1, respectively, and 0.250 mg mL-1 of butylated hydroxytoluene (positive control). DSFH from different regions exhibited antifungal activity against Candida albicans. The results show that the chemical composition and the biological activity of DSFHs can be affected according to the area of collection.

Resumo em Inglês:

Groundwater is considered an important source of water aid for human consumption. However, this water can be contaminated by impurities, such contamination spots that might reach the water tables. The aim of this study was to investigate the quality of shallow groundwater in Flores neighborhood, located in the municipality of Benevides, within Belém metropolitan region, State of Pará, Brazil. Recommendations described in Standard Methods for Examination of Water and Wastewater were followed at the time to determine physical-chemical parameters such as potential hydrogen (pH), electrical conductivity (EC), total dissolved solids (TDS), apparent color, turbidity, total hardness (TH), ions and trace elements. Multivariate statistical analysis has shown that most predictive water-quality parameters set for human consumption are associated with natural events involving weathering and leaching processes. Nevertheless, parameters of nitrate, phosphate, EC, TDS and pH are also influenced by anthropic conditions in the surroundings, mainly phosphate and nitrate ions. Therefore, it can be concluded that shallow groundwaters in Flores neighborhood are unsuitable for human consumption, making it necessary for municipal public authorities to take action to solve the problem of water shortage in the borough, thus preventing the population from use those shallow groundwaters, as their consumption can bring health problems.

Resumo em Inglês:

The recycle and utilization of expired drugs is a challenge for many countries at present. The employment of expired drugs as green corrosion inhibitors is expected to address both drug recycling and corrosion prevention issues, with significant economic and environmental value. Herein, the individually and combination corrosion inhibition performance of expired amoxicillin (AMC) and penicillin V potassium tablets (PVP) for lowcarbon steel in 20% acetic acid solution containing 600 mg L-1 chloride ion are evaluated by electrochemistry and weight loss method. Both the AMC and PVP present the mixed-type corrosion inhibitors mainly affect the cathode process when used individually. The optimum inhibition efficiency is 61.22% (AMC) and 79.21% (PVP), which all appear in 5.0 × 10-3 mol L-1. The AMC and PVP are adsorbed on the steel surface by mixed physisorption and chemisorption, which are consistent with the Langmuir adsorption isotherm. The corrosion inhibition rate drops sharply when AMC and PVP are combined use with a close mole ratio. But a small amount of PVP significantly enhance the corrosion inhibition effect of AMC, the corrosion inhibition rate from 61.22 to 79.72%. The corrosion inhibition rate of AMC and PVP combination inhibitor decreased with the increase of temperature.

Resumo em Inglês:

In this work, using the PM3 semi-empirical method, the oxidation of the single-walled carbon nanotube (SWCNT) was studied by sulfuric and nitric acid for the incorporation of carbonyl (C=O), phenol (OH) and carboxylic (COOH) groups in the C=C bonds present on the surface of the nanotube. Subsequently, the crosslinking of the oxidized SWCNT (SWCNTox) and chitosan (Q) was observed through hydrogen bonds of the C=O and OH bonds with 2.34 Å, the process was endothermic and soluble in polar solvents due to the presence of OH and NH groups in the structure of SWCNTox/Q. The Monte Carlo modeling allowed to study the adsorption of pesticides in the SWCNTox/Q at different temperatures, where the QSAR (quantitative structure activity relationship) properties allowed predicting the behavior of the pesticides, that is, the degree of hydrophobicity (log P) and accessible surface area (ASA) were important parameters in the evaluation of SWCNTox/Q as an adsorbent and surface interacting with pesticides respectively. Finally, the adsorption was a physisorption process due to the electronegativity of the CO, OH, NH2, NH and C=O bonds.

Resumo em Inglês:

Two novel alkyl thiophene-modified pyrene derivatives (1)-(2) were created and synthesized using palladium-catalyzed Stille coupling processes and Friedel-Crafts reaction of pyrene. The polycyclic aromatic groups of the thiophene-modified pyrene were oxidized with Ag[Al(OC(CF3)3)4] to provide the insensitive radical cations 1•+-2•+ based on the alkyl thiophene-modified pyrene derivatives. Nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), UV-Vis spectroscopy, and density functional theory (DFT) calculations, were used to investigate their structures and properties. The pyrene moieties were the primary location of the electron spin distribution, with a little overflow onto the outer thiophene moieties. Due to the different substituent groups, free radicals 1•+ 2•+ exhibit some different properties. Compound 1•+ is the most extensive thiophene-modified pyrene radical cation that has been reported. These species are anticipated to have wide-ranging potential in the areas of optoelectronic materials and semiconductors.

Resumo em Inglês:

Nanoparticles of TiO2 doped with low amount of Fe were synthesized from natural ilmenite obtained from alluvial gold mine wastes. The obtained TiO2 were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance, thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), N2 adsorption-desorption isotherms, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results confirm the formation of mesoporous TiO2 nanoparticles in anatase phase with 0.05 wt.% of iron possibly replacing some titanium places. All the characterizations were performed to the synthesized solid and the reference materials (TiO2 anatase and Degussa P25). The photocatalytic activity of both the synthesized solid and references were evaluated in the photo-oxidation of cyanide in aqueous medium under UV illumination. An experimental design type Box-Behnken was performed choosing three different parameters: the initial concentration of cyanide (50, 150 and 250 ppm) the catalyst load (0.1, 0.5 and 1.0 g L-1) and the oxygen source. The percentage of cyanide conversion was chosen as response in the design obtaining as optimal conditions [CN-]0 = 50 ppm, catalyst load = 0.6 g L-1 and air bubbling. Under these conditions it was reached 32, 32 and 89% of cyanide conversion for Fe-TiO2 synthesized, TiO2 anatase and Degussa P25, respectively.

Resumo em Inglês:

The antifouling booster biocides are frequently studied for toxic effects on the aquatic ecosystems. The present investigation proposes passive silicone rubber samplers as a collection method for biocides, once these methods can concentrate substances in aqueous matrices at very low levels. Through the passive sampler-water partition coefficient (Ksw) and the analyte chemical nature, we can optimize their extraction from the membrane to apply in the sample medium. We used the co-solvent method to determine the Ksw of three third-generation antifouling biocides, chlorothalonil, dichlofluanid, and dichlorooctylisothiazolinone (DCOIT), with log Ksw = 2.24, 4.01, and 2.38, respectively. Improving extraction also led to a recovery range higher than 70%, determinations were carried out by gas chromatography with an electron capture detector. Biocides concentration in seawater samples from Itaqui port (São Marcos Bay, northern Brazil) ranged from 0.058 to 0.72 µg L-1 for chlorothalonil, 0.001 to 0.008 µg L-1 for dichlofluanid, and 0.018 to 0.64 µg L-1 for DCOIT.

Resumo em Inglês:

Seeking a viable alternative to fossil fuels as the primary energy source, bioethanol has emerged as a promising second-generation fuel derived from lignocellulosic biomass. With Brazil ranking pineapple as the third most produced fruit in temporary crops, this study aims to assess the impact of chemical pretreatment techniques, specifically organosolv and diluted acid, on the residual biomass of Pérola pineapple peel to enhance bioethanol production. Employing an experimental design that incorporates temperature, reaction time, and varying concentrations of organic solvent, the study examines their effects on the susceptibility of the substrate to saccharification for future bioethanol generation. Factors such as alphacellulose, hemicellulose, and lignin were evaluated in triplicate and subjected to statistical analysis using the Tukey test with a confidence level of 95%. Upon application of the pretreatment methods, it was observed that the organosolv solvent approach (utilizing water and ethanol) with sulfuric acid exhibited superior sugar conversion, yielding the highest concentration of xylose at 9.13 g L-1. Additionally, the pretreated biomass contained 1.38 g L 1 of cellobiose, 3.11 g L-1 of arabinose, and 3.76 g L-1 of glucose. This technique demonstrates promising potential for obtaining fermentable sugars crucial for bioethanol production.

Resumo em Inglês:

Alzheimer’s disease (AD) is a most common form of dementia and results in memory loss, disorientation, impaired thinking and changes in personality as well as mood. The dementia cases mostly turn into the Alzheimer’s disease (AD). Another disease, the Parkinson’s disease (PD), mainly affects dopaminergic neurons in substantia nigra. A series of previously synthesized quinolone-triazole hybrids were investigated and evaluated for their anti-acetyl cholinesterase and against monoamine oxidase reactive properties through in silico characterization. The ground state electronic properties were determined by electron density of the compounds through DFTs (density functional theory) calculation. The geometries of all compounds were optimized using Becke-3-parameter-Lee-Yang-Parr (B3LYP) method and 6-311g basis set. Docking studies were conducted using the AutoDock and Molecular Operating Environment (MOE) software and the results of the potent derivatives found to be encouraging. The data confirmed that all the compounds have drug-like properties and was further confirmed by ADMET (absorption, distribution, metabolism, excretion and toxicity) properties.

Resumo em Inglês:

Even though ammonia is a natural component of aquatic environments, elevated concentrations indicate pollution and environmental degradation. Consequently, efficient analytical methods for monitoring ammonia levels are crucial for preserving water quality. Voltammetry offers a sustainable approach for NH3 quantification, combining good analytical performance with low sample and reagent consumption, minimizing waste generation. However, despite these advantages, the voltammetric determination of ammonia remains relatively unexplored. Therefore, this study investigated the electrochemical behavior of NH3 in alkaline solutions using a non-modified Pt electrode and evaluated the performance of differential pulse voltammetry (DPV) and square wave voltammetry (SWV) for NH3 determination. DPV provided superior performance, with limits of detection and quantification of 0.79 µmol L-1 (0.011 ppmN) and 2.6 µmol L-1 (0.036 ppmN), respectively, which comply with the maximum allowable ammonia concentration in natural waters according to Brazilian and European regulations. The voltammetric method successfully quantified ammonia in tap and river water samples, providing results concordant with the established Berthelot spectrophotometric method, at a 95% confidence level. Additionally, it is simple and fully accessible to non-electrochemist since no sophisticated procedures for electrode modification are needed. Finally, the high analytical performance of the proposed method makes it valuable for pollution monitoring in aquatic environments.

Resumo em Inglês:

Efavirenz, an antiretroviral drug, is a class 2 according to the biopharmaceutics classification system. Many dissolution enhancement systems have been tried and our group had success using wet milling to decrease particle size and granules were obtained by spray and freeze drying. In this paper we present data related to the upgrade in the process, raising the solids concentration in the suspension from 10 to 50% (m/v) and changing the drying step for a fluid bed granulation. After that, tablets were obtained. Granules and tablets were fully evaluated and a pharmacokinetic study was also performed with the granules. By powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR) it was possible to prove that there was no phase transition in the sample after milling and drying. Dissolution efficiency of 4 from 5 granules was higher than 90%, considering 83% for the raw material. Tablets were technically approved but the dissolution was impacted and just 2 out of 11 showed results > 80%. A high enhancement in the bioavailability was also observed, around 172%. So, it is possible to conclude that efavirenz microcrystals with enhanced dissolution and bioavailability can be formulated into tablets and are a viable system to develop a new drug product.

Resumo em Inglês:

Fruits of Schinus terebinthifolia Raddi were investigated. A fast and efficient method for the simultaneous determination of 11 polyphenolic substances by high performance liquid chromatography-diode array detector (HPLC-DAD) was applied. Limits of quantification ranged between 0.78 and 3.14 mg L-1. High concentrations of kaempferol were found. An exploratory evaluation was performed using principal component analysis (PCA) for fruit origin differentiation. Total phenolic content (TPC) ranged from 274 to 517 mg GAE 100 g-1; total flavonoid content (TFC) ranged from 101 to 283 mg QE 100 g-1. In vitro analyses showed that antioxidant capacity with 2,2-diphenyl-1-picrylhydrazyl (DPPH) ranged from 1.7 to 7 µM DPPH 100 g-1. The bacteriostatic and bactericidal effect were also evaluated against: Bacillus subtilis, B. cereus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella choleraesuis, Candida albicans and C. glabrata, using broth microdilution assay. It can be inferred that S. terebinthifolia Raddi fruit has the potential to act as an ally in the search for new alternatives in the action against pathogens, and it can be used as a potential natural antioxidant and antimicrobial agent. Metals (Cu, Fe, Mg, Mn and Zn) were also determined by flame atomic absorption spectrometry (FAAS), with emphasis on high concentrations of Mg, Zn and Fe.

Resumo em Inglês:

Sensor calibration for dissolved gas is a critical and necessary step to ensure consistent sensor response over time and under different conditions. In this work, we describe a 3D printed device that facilitates the calibration of gas sensors. The device effectively maintained gas concentration in the solution for at least 2 h. Analytical curves were constructed in the pH range of 2 to 12, yielding determination coefficients surpassing 0.98. The chosen method proved suitable for the calibration of the sensors. Furthermore, using accurate and reliable reference sensors contributed to obtaining precise and trustworthy measurements.

Resumo em Português:

The training of Chemistry teachers in Brazil has been researched for a few decades and studies point out to training gaps that reverberate in teaching, especially in basic education. One of the contents covered in this step and which is part of the high school curriculum is radioactivity, which is related, among other things, to radiological and radioactive accidents that occur around the world. Thus, this research sought to investigate how the training provided to Chemistry undergraduates in the state of Goiás is in relation to the subject of radioactivity, since in 1987 a radiological accident occurred in Goiânia with a Cesium 137 source. This is a qualitative research, data were collected via questionnaire and the analytical technique used was discursive textual analysis (ATD). The results showed that due importance was not given to the radiological accident, since there is evidence of training gaps in relation to the topic of radioactivity in Chemistry degree courses in the state of Goiás, where the accident occurred, and the contents on radioactivity are either not addressed, or the approach is superficial. This fact directly impacts the teacher’s performance in basic education, when working on this content with their students.

Resumo em Português:

Chemometrics is gaining more and more space in universities and industry. To contribute to the development and expansion of principal component analysis (PCA) teaching proposals, this work evaluated the answers of the students to a questionnaire and presented a didactic-pedagogical proposal that can contribute to solving the principal doubts achieved by students in the PCA interpretation. Based on data collected in a semi-open questionnaire, the proposal was developed based on methodological principles of historical-critical pedagogy, containing the objectives, the problems surrounding the topic, and the cultural instruments necessary for understanding and interpreting PCA in the discipline of chemometrics by using new resources and instruments, especially free software, Chemostat. This proposal covers topics related to the concept of chemometrics and PCA, the explanation of the data set, pre-processing, use of Chemostat software, and analysis of principal components. It is hoped that this proposal can promote a better understanding concerning PCA on the part of students, as well as effective incorporation of the phenomena that involve this tool and its applications, and interpretation. Likewise, it is expected that this didactic-pedagogical proposal can support new teaching practices in chemometrics subjects in higher education.

Resumo em Português:

In the present article, the scientific journey that led to the development of the Nernst equation, a cornerstone in modern electrochemistry, is discussed. The paper not only explores historical achievements but also traces the evolution of scientific ideas and highlights the key figures who laid the conceptual and experimental groundwork for the seminal contributions of Nernst to the understanding of electrochemical systems. In this exploration, particular attention is paid to the examination of the first three articles published by Nernst between 1888 and 1889. These essential works marked the inception of the engagement of Nernst with the Leipzig Physical Chemistry circle, comprising the distinguished quartet: van’t Hoff, Arrhenius, Ostwald, and Nernst himself. Furthermore, the present study examines the intricate relationship between the Nernst equation and the four basic laws of Thermodynamics, all in an approach accessible to undergraduate students. A concise review elucidates the interpretation and significance of these foundational thermodynamic principles and explain how they hold the formulation of the Nernst equation.

Resumo em Inglês:

In this work, the innovation process to take chemical technologies born in universities to the market is described. The discussion is structured on the stages: research/science, patenting, opportunity evaluation, scale-up and proof of concept that lead to two possible outputs: technology transfer or startup creation. The work also describes the activities of Escalab, a UFMG technology lab, in the innovation process: technological mapping/R&D for the industry, technology scale up, technology acceleration, open innovation programs with industry and the program “go-to-market” for the insertion of chemical startups in market. It is expected that this experience should motivate academic chemistry researchers to push their technologies to the market.