Resumen en Inglés:

In this study, the Raman spectra of ortho-hydroxybenzoic acid (O-HA), meta-hydroxybenzoic acid (M-HA), and para-hydroxybenzoic acid (P-HA) molecules were recorded in the Raman shift range of 200-800 cm-1 using the Raman time domain spectroscopy (R-TDS) technique. The characteristic Raman scattering peaks of these three isomers of hydroxybenzoic acid were obtained, and it was found that there are significant differences in peak frequencies between O-, M-, and P-HA. Concurrent with the experimental study, theoretical calculations were performed on the molecular crystal cell of hydroxybenzoic acid using density functional theory (DFT), simulating the experimental Raman spectral features, and the results were in good agreement with the experimental data. The potential energy distribution (PED) is employed to examine the distinct vibrational modes of O-, M-, and P-HA molecules, as well as to assess the contribution of these various vibrational modes to the overall potential energy. The results indicate that R-TDS can distinguish the subtle differences between chiral isomers of hydroxybenzoic acid. The significance of this research lies not only in the scientific insights it provides but also in its practical implications for material science, pharmaceuticals, environmental monitoring, and forensic science, where the accurate identification and characterization of materials are of paramount importance.

Resumen en Inglés:

The pyrolytic kinetics of sunflower seed husks (SSH) are investigated based on previous activation energy data. By applying the kinetic compensation effect (KCE), the average value of the frequency factor was 3.517 × 109 s-1. Through the numerical reconstruction, the two-dimensional reaction model, based on diffusion phenomena, [-ln(1 - α)]-1, best represented the pyrolysis of SSH; where α is the mass conversion of the material. The calculated kinetic parameters efficiently predicted experimental kinetic behavior since they presented lower deviations, with a maximum magnitude of 6%. These results indicated that the proposed methodology was suitable to describe the pyrolysis of SSH. This work is the first study on the kinetic triplet for the pyrolysis of heterogeneous biomass (SSH) using the KCE, with the construction of theoretical curves and the comparison with master plots methodology.

Resumen en Inglés:

In recent decades, increasing concerns about heavy metal contamination in wastewater and the high costs associated with conventional removal methods have driven the search for greener and more cost-effective adsorbents. In this study, we focused on a hybrid composed of tannic acid (TA) and magnetite nanoparticles (Fe3O4@TA) as an alternative for removing CdII and PbII from aqueous solutions. Characterization techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI TOF-MS), and Fourier transform infrared spectroscopy (FTIR), were employed to confirm the nanometric nature of the composite and its organic-inorganic composition. Several adsorption parameters, such as pH, contact time, adsorption kinetics, and initial ion concentration, were evaluated. Sorption kinetic data were best described by the pseudo-second order kinetic model, providing equilibrium rate constants (k2) of 0.0194 g mg-1 min-1 for CdII and 0.0134 mg-1 min-1 for PbII. Furthermore, the adsorption isotherms for the Fe3O4@TA adsorbent exhibited a better fit to the Freundlich isotherm model compared to the Langmuir isotherm model. This nanocomposite holds promise as a sustainable and economical solution for heavy metal removal from wastewater.

Resumen en Portugués:

Tea is consumed worldwide and recognized for its health benefits due to the presence of bioactive compounds and micronutrients such as copper (Cu). This study proposes a method for determining Cu in tea by graphite furnace atomic absorption spectrometry and Box-Behnken design to obtain optimal extraction conditions using deep eutectic solvent (DES). The DES, composed of choline chloride and oxalic acid (1:1 molar ratio), was employed. The optimized temperature program for Cu determination used pyrolysis at 900 °C and atomization at 2100 °C. The best extraction conditions were found using 50 mg of sample, DES containing 20% (m m-1) of water and 45 min of ultrasound-assisted extraction at 60 °C. The accuracy of the method was evaluated by analysis of certified reference materials (agreement from 95 to 112%) and the precision was assessed by the relative standard deviation (RSD < 10%, n = 3). The obtained limit of detection (0.2 mg kg-1) was suitable for analyzing teas. In the black, green and herbal teas analyzed, the total Cu concentration ranged from 2.5 to 35 mg kg-1 and the infusion extracted concentrations were up to 90%. Overall, the proposed method showed to be well-suited to determine the total and infusion extracted Cu concentrations in teas.

Resumen en Inglés:

The agraz (Vaccinium meridionale Swartz) fruit is an anthocyanin source with antihypertensive in vitro activity. V. meridionale fruit powders were obtained by spray-drying (SD) with maltodextrin DE-20 (MD). A polar extract was obtained by acetone-water extraction and then partitioned with solvents of increasing polarity. The anthocyanin-rich extract was microencapsulated using two inlet temperatures (120 and 150 °C) and two ratios between fruit (AGZ) and encapsulating agent (MD) (1:1 and 2:3, w/w). The four microencapsulated powders (M1-M4) were physicochemically characterized; the total phenolic content and the in vitro antihypertensive activity (inhibition of the angiotensin-I enzyme, ACE-I) were measured in the freeze-dried fruit and polar fractions. V. meridionale fruit has potential as an ACE-I inhibitor, with delphinidin and cyanidin derivatives being among the chemical compounds responsible for this activity. The physicochemical, morphological, thermal, and biofunctional properties of microencapsulates were evaluated, finding that the M1 and M3 samples (120 °C, 1:1, and 150 °C, 1:1, respectively) showed the highest antihypertensive activity value. These results suggest that V. meridionale could be used to develop microencapsulates with biofunctional properties, which can be used as additives for different food matrices.

Resumen en Inglés:

This study investigates the corrosion mechanism of 1020 carbon steel in strong acid solutions, relevant for industrial applications, using simple and effective laboratory methods. Direct (weight loss) and indirect (pH, ionic conductivity, open circuit potential and polarization curves) negotiations were performed to evaluate the corrosion rate in different concentrations of hydrochloric acid (HCl) and nitric acid (HNO3). In the HCl system, zero-order kinetics were confirmed (k = 10–5 min g–1), indicating a bottleneck in the corrosion mechanism, confirmed by electrochemical tests and metallographic analyses that showed uniform corrosion. In the HNO3 system, corrosion had first-order kinetics in the first 60 min (k = 10–2-10–3 min g–1), followed by passivation of the steel surface due to the presence of nitrate ions. These findings are particularly relevant for the acid pickling industry, where HCl is more stable, while HNO3 accelerates corrosion, requiring additional regulations. The results obtained are useful for the development of corrosion control and prevention strategies, contributing to increase the durability of materials and optimize the efficiency of industrial processes.

Resumen en Portugués:

Ultraviolet-visible (UV-Vis) absorption spectroscopy is widely used in chemistry to analyze electronic structures and molecular properties. Computational chemistry, particularly density functional theory (DFT) and time-dependent DFT (TD-DFT), offers valuable tools to support and complement experimental studies. This study evaluates various functionals and basis sets to describe the ground-state geometry and UV-Vis spectra of trans-azobenzene (trans-AB) and 3-ferrocenyl-trans-azobenzene (3-FCAB). The results indicate that M06-L/def2-TZVP describes trans-AB, while ωB97X-D3(BJ) is more suitable for the ground-state properties of 3-FCAB, with O3LYP performing best for excited-state properties. The Pauling point concept emerges as a guiding principle, highlighting the balance between computational cost and accuracy. Our findings suggest that gas-phase optimized geometries can yield accurate TD-DFT spectra, avoiding unnecessary complexity from solvation effects. The study reinforces systemand property-dependent nature of DFT, emphasizing the need for testing different density functionals. It provides a guide and recommends functionals as starting points for treating similar organic and coordination compounds.

Resumen en Portugués:

Gas flow measurement is a necessity in many areas of chemical research. One equipment used for this end is the bubblemeter or soap-flowmeter. The principle of this instrument is based on measuring the time it takes for a thin film of soap - a bubble - to move through an area with a known volume. The analog version of this equipment present limitations, such as the dependence on analyst monitoring and the associated ergonomic risk. This work presents the development of a digital soap flowmeter portable and autonomous. The instrument uses light emitting diode (LED)-photodiode pairs, a signal treatment system and microcontroller for operating independently of a PC or laptop. This work automated the detection of the thin film passage for measuring the initial and final times of detection, thereby minimizing errors present in analog bubblemeters. For ensuring precision, the instrument was calibrated with an analog bubblemeter. Additionally, tests with multiple gases were conducted for validating the results, whereupon digital and analog soap-flowmeters were satisfactorily concordant. The portability and precision of the designed device ensure it is adequate for laboratorial and field usage, guaranteeing quick and safety in the measurement of gaseous flow.

Resumen en Inglés:

The activities of tanneries and electroplating industries are hazardous in the context of water and soil contamination by heavy metals. The use of biological materials for the adsorption of heavy metals presents as an important treatment alternative. This work evaluated the capacity of Chlorella sorokiniana and Heterochlorella luteoviridis biomasses to absorb heavy metals commonly found in these industrial wastewaters. The heavy metal uptakes were 61.4% Cu2+, 90.2% Cr3+, 6.9% Cr6+, 93.7% Fe2+, 90.6%, Fe3+ and 70.3% Zn2+ for H. luteoviridis, and 65.6% Cu2+, 75.7% Cr3+, 5.4% Cr6+, 86.0% Fe2+, 63.5%, Fe3+ and 62.7% Zn2+ for C. sorokiniana. Regression analysis showed that sorption capacity was dependent on the microalga, the heavy metal concentration in solution and the atomic number of the adsorbate. These results indicated that the use of microalgae as biosorbents is a promising alternative technology, and the efficient removal of iron has been highlighted.

Resumen en Portugués:

Absorbable sutures are used to provide temporary support to tissue during healing, degrading in the body and not requiring surgical removal. However, some have low biocompatibility, are difficult to handle and undergo uncontrolled degradation. Natural biomaterials, such as chitosan and egg testis membrane, appear as promising alternatives. This study evaluated the effect of adding testis membrane powder to biodegradable suture threads, analyzing physicochemical, mechanical and biological properties, in addition to the use of riboflavin and ultraviolet (UV) light as crosslinking agents. The samples were subjected to Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), tensile strength, swelling degree and cytotoxicity tests. FTIR spectra confirmed the formation of crosslinks (C-O-C and C=N), which increased the structural stability of the threads. EDS spectroscopy revealed a higher concentration of nitrogen in the crosslinked samples. Morphological analyses indicated denser and more uniform surfaces, and crosslinking improved mechanical properties. The incorporation of testate membrane powder into chitosan threads, together with the crosslinking process, demonstrated significant improvements in the studied properties, indicating the potential of these threads in absorbable sutures.

Resumen en Inglés:

Organosolv pretreatment with glycerol was applied to the corn straw and corn cob biomasses individually and mixed. The reactions were carried out to improve the amount of FeCl3 catalyst, the use of crude glycerol, and eliminate the steps of washing and drying the pretreated biomass before it was subjected to enzymatic hydrolysis. The results indicated that the straw and cob behaved very similarly in the different pretreatment situations, with the condition using 0.0125 mol L-1 of FeCl3 being considered the best for both. It was evident that the FeCl3 catalyst reduces the recalcitrance of biomasses, acting in the removal of hemicellulose and lignin to the pretreatment liquor. The 50% cob + 50% straw mixture, pretreated according to the best condition, provided sugar release analogous to that of the biomasses individually. Excellent cellulose recovery was obtained (98.2%), in addition 99.2% of hemicellulose and 89.5% of lignin were removed using commercial glycerol with 0.0125 mol L-1 of FeCl3. From 1 kg of 50% cob + 50% straw in natura, 360.9 g of glucose was obtained in 24 h of hydrolysis. The application of crude glycerol was promising, and the pretreated biomass can be subjected directly to enzymatic hydrolysis, without washing and drying.

Resumen en Inglés:

The presence of contaminants, especially pharmaceuticals, in concentrations ranging from ng L-1 to μg L-1 has been the focus of numerous studies and is considered an emerging concern due to their adverse effects on aquatic biota and even human health. In this context, this study aimed to optimize a photoreactor equipped with four 24 W ultraviolet (UV)-A lamps and thin films of silver-doped titanium dioxide (Ag/TiO2), evaluating parameters such as catalyst concentration, pharmaceutical concentration, matrix effects, and pharmaceutical quantification using high-performance liquid chromatography (HPLC). The immobilized Ag/TiO2 catalysts were used for the photodegradation of the pharmaceuticals naproxen, diclofenac, and mefenamic acid. Photocatalysis tests were initially conducted in ultrapure water, followed by dispersive liquid-liquid microextraction with solidification of floating organic drops (DLLME-SFOD) on a real sample from São José Bay (Maranhão, Brazil) to identify the pharmaceuticals present and evaluate the degradation process. Naproxen and diclofenac were detected in the environmental sample, and results showed that photolysis alone was insufficient to degrade the compounds in brackish water. Therefore, photocatalytic treatment using Ag/TiO2 was necessary, achieving 100% degradation of diclofenac in 7 h, 100% of mefenamic acid in 4 h, and 90% of naproxen in 10 h. This research highlights the effectiveness of the optimized photoreactor with Ag/TiO2 thin films in treating real matrices to achieve high drug degradation rates.

Resumen en Portugués:

Lubricating oil is essential for operating internal combustion engines, protecting parts, reducing friction, and dissipating heat. However, water can lead to corrosion, oxidation, and sludge formation, reducing viscosity, and lubricating capacity. This study reports moisture determination in an engine lubricating oil. The engine lubricating oil and the radiator water were changed at a gas station. The position is very close to the front of the truck. However, the engine melted after this change after 16 km of driving. Thus, a technical report was conducted and reported using six different analytical strategies determining moisture in lubricating oil: centrifugation and weighing in a balance, oven drying and weighing in a balance, drying and weighing in a thermogravimetric analyzer, drying and weighing in a moisture balance analyzer, simple distillation and weighing in a balance, and identification by infrared spectroscopy. The moisture content in the sample was 46.1 ± 7.7%, corroborating with water addition in the lubricating oil. The accuracy was assessed through recovery assessment (90 ± 5%) and results comparison. The importance of controlling humidity in commercial lubricating oils is also highlighted, and analytical strategies described in the present study can be alternatives to certify the quality of commercial lubricating oil.

Resumen en Inglés:

The cold start of fuel cells presents a major bottleneck in commercialization, with auxiliary heating strategies serving as a crucial method to achieve rapid cold start. In response to this challenge, a one-dimensional multi-phase cold-start stack model was developed to explore optimization strategies for cold-start performance. Utilizing the non-dominated sorting genetic algorithm (NSGA)-II, coolant flow rate, positive temperature coefficient (PTC) heating power, and load rate were comprehensively optimized to determine the optimal auxiliary heating strategy. The findings reveal that increasing the load rate enhances both the growth of the cathode ice volume fraction and the temperature rise rate; however, excessively high rates may lead to polarity reversal, with an optimal range identified between 0 and 0.04 A cm–2. A coolant flow rate of 0.1-0.5 kg s–1 improves temperature uniformity, and the PTC heater enhances both the temperature rise rate and voltage stability. The optimal solution was identified as a coolant flow rate of 0.45 kg s–1, PTC power of 2375 W, and a load rate of 0.02268 A cm–2, significantly reducing the minimum cold-start temperature to 247.15 K and improving cold-start performance.

Resumen en Inglés:

Comparative studies of the drugs salbutamol and ipratropium bromide have been conducted to evaluate their effectiveness in treating respiratory problems such as asthma and chronic obstructive lung disease (COPD). In addition, their electronic structures, frontier molecular orbitals and other parameters were analyzed. Our aim was to elucidate the fundamental differences in their reactivity profiles. Our analysis included highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gaps, thermodynamic studies, global chemical parameters, molecular electrostatic potential (MEP) maps and Mulliken charge distributions analysis to provide insights into their chemical behavior. The results highlight significant variations in the reactivity of salbutamol and ipratropium bromide, offering valuable information for their therapeutic application and potential modifications. This study underscores the importance of computational techniques in understanding drug reactivity, aiding in the rational design of more effective respiratory medications.

Resumen en Inglés:

Pumpkin seed meal, a by-product of pumpkin seed oil extraction, is recognized for its high protein content. Traditional extraction methods, such as alkaline extraction and acid precipitation, are associated with significant drawbacks, including high chemical consumption, low yield, and equipment corrosion. This study investigates the efficacy of a deep eutectic solvent (DES) system, composed of choline chloride and urea (1:2 molar ratio), for protein extraction from pumpkin seed meal, comparing it with conventional alkaline methods. The optimized conditions included 30% (m/m) water content in the DES, ultrasound treatment for 40 min at 50 °C, and a liquid-to-solid ratio of 20 mL g-1. The protein content in the extract reached 66.09 ± 2.82%, demonstrating the potential of DES as a sustainable and efficient alternative. Furthermore, the DES could be recovered and reused, highlighting its environmental and economic benefits. This study confirms the viability of choline chloride-urea DES for protein extraction, offering significant improvements over traditional methods.

Resumen en Portugués:

The identification of gemstones requires increasingly precise analytical methods due to advances in synthesis and treatment techniques, which heighten the risk of fraud. Portable Raman spectroscopy stands out as a non-destructive and efficient tool for these analyses, providing detailed structural information. This study aimed to apply portable Raman spectroscopy to the characterization of gemstones seized by the Civil Police of Espírito Santo (PCES) and contribute to the creation of a spectral database. Eleven seized samples and seven authentic gemstones from the Federal Institute of Espírito Santo (IFES) were analyzed using a portable Raman spectrometer, along with refractive index and absolute density measurements. The results revealed discrepancies between the presumed classification and the actual composition: the supposed blue emeralds were identified as apatites, while the alleged topazes exhibited spectral characteristics of authentic amethysts. Multivariate statistical analysis (principal component analysis, PCA) and hierarchical analysis demonstrated distinct groupings, aiding in sample differentiation. The study confirms the potential of portable Raman spectroscopy, combined with chemometrics, for gemstone identification, reinforcing forensic investigations and improving gem authentication protocols.

Resumen en Inglés:

We synthesized a series of citral hydrazone derivatives as inhibitors of Colletotrichum gloeosporioides and determined their half-maximal effective concentration (EC50) values. The formylhydrazine (4q) synthesized from citral exhibited the strongest inhibitory effect against Colletotrichum gloeosporioides, with an EC50 value of 1.6548 mg L–1. In addition, after treatment with 4q, the conductivity of C. gloeosporioides treatment solution increased with the increasing concentration, while the soluble protein and reducing sugar contents decreased as the treatment concentration increased. Molecular docking studies showed that the binding of 4q to chitin synthetase was primarily driven by hydrogen bonds and hydrophobic interactions. The binding of 4q to succinate dehydrogenase, on the other hand, was mainly driven by three hydrogen bonds. In summary, this study confirmed a novel inhibitor of C. gloeosporioides, which is expected to be developed into a new antifungal drug, promoting the healthy development of the Camellia oleifera industry.

Resumen en Inglés:

The textile industry’s reliance on nanotechnology, including in developing smart textiles, has raised significant concerns due to the improper disposal of toxic nanomaterials and the release of nanowaste into ecosystems. These challenges pose risks to human health and the environment, emphasizing the urgency of adopting sustainable practices aligned with global circular economy goals. This study aims to compile and analyze the existing research on nanotechnology to improve the sustainability of the textile supply chain. To fulfill this aim, a systematic literature review was guided by the PRISMA protocol and bibliometric and content analyses of articles published between 2004 and 2024, revealing key approaches such as green synthesis, advanced recycling methods, sustainable nanomaterial design, and efforts to replace hazardous substances. Despite these advancements, barriers related to cost, scalability, regulatory challenges, and stakeholder acceptance persist, limiting widespread implementation. This research provides valuable insights into environmentally conscious practices by bridging sustainability and nanotechnology. It supports adopting circular economy principles in textile production chains, contributing to the advancement of sustainable nanotechnology applications in the industry.

Resumen en Inglés:

Cannabis sativaL.: A CRITICAL REVIEW OF CANNABINOIDS, LEGISLATION, AND ANALYTICAL METHODS. Forensic chemistry plays a crucial role in criminal investigations, utilizing techniques to analyze evidence such as gunshot residues, explosives, and illicit drugs. Among these, Cannabis is widely studied due to its medical and recreational use, especially considering that it is the most trafficked drug worldwide. The plant contains over 700 compounds, including around 120 cannabinoids. Overall, cannabinoids have been used to treat several health problems such as chronic pain, nausea, and vomiting, among others. Despite its therapeutic potential, recreational use is associated with health risks, including cardiovascular issues, cognitive impairment, mental disorders, and addiction. The cannabinoids market has increased significantly along with interest in Cannabis products as a drug, leading to a need for novelty in instrumental analysis and methods to support quality control laboratories and scientific police forces. In this sense, the analysis of cannabinoids in various matrices primarily relies on chromatographic techniques. Gas chromatography (GC), often coupled with mass spectrometry (MS) or a flame ionization detector (FID), is widely used. However, liquid chromatography (LC) offers advantages in preserving acidic cannabinoids and preventing their degradation. Therefore, all the processes concerning Cannabis were addressed in this study, from its composition to legislation and chemical evaluation.

Resumen en Inglés:

Misinformation is a pervasive threat to democracy, human health, the environment, and many other spheres touched by society. This raises concern about what citizens need to know so they can identify and avoid false claims, making individual and collective decisions based on evidence. Reliable scientific knowledge reaches the public through science communication. However, simply communicating ready-made claims is not enough to empower people in their daily decision-making. Aiming to contribute with possible pathways for science education for social transformation, a didactic activity in which undergraduate students designed science communication pieces was developed. It was implemented in three different undergraduate Chemistry courses, resulting in 67 science communication pieces. This study aimed to identify indications of scientific literacy in students’ productions by analyzing them for the presence of the Structural Axes of Scientific Literacy. The results showed that the majority of the pieces presented axes (1) Scientific Concepts and (3) Science, Technology, Society, and Environment (STSE), while axis (2) Nature of Science (NOS) was addressed in about one-third of them. This reinforces that epistemology of science needs to be highlighted in science education curricula and practice. Yet, based on the results, the science communication pieces complied with socially engaged scientific literacy.

Resumen en Portugués:

The introduction of the concepts of Green Analytical Chemistry in the teaching of Chemistry has been growing, in view of the formation of students more attentive to sustainable development. However, many experimental classes still employ reagents of high toxicity, which generate class I residues, as is the case of dichrometry, a titulometric method. Using the determination of iron in a dietary supplement and in a steel sponge as motivating examples, this paper presents microtitration as a greener alternative for classroom use. The method is compared to the classical approach, highlighting differences in chemical exposure and waste volume, emphasizing the environmental benefits of microtitration. The experiment allowed students to develop critical thinking about traditional methods and became familiar with the manipulation of microvolumes and microscale reasoning. Their evaluations of the proposed practice were recorded and discussed, for a possible replacement of the classical method.