Abstract in English:

Ultraviolet (UV) radiation is a public health issue, especially in tropical and subtropical regions, where intense solar exposure contributes to a higher incidence of skin cancer. The growing concerns surrounding synthetic UV filters have prompted the search for natural and sustainable alternatives. The Brazilian semi-arid region represents a unique ecosystem whose flora harbors bioactive metabolites that exhibit remarkable potential for pharmaceutical and cosmetic innovation. This study investigated the chemical composition, antioxidant capacity, and photoprotective properties of two Evolvulus species (Convolvulaceae Juss.) native to this biome: E. frankenioides and E. glomeratus. Total phenolic and flavonoid contents were quantified using the Folin-Ciocalteu and aluminum chloride methods, while antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, and the sun protection factor (SPF) was determined using the Mansur method. E. glomeratus exhibited higher phenolic content (172.61 mg GAE g–1), stronger antioxidant activity, and superior SPF (13.89) compared to E. frankenioides. Both extracts exceeded the minimum SPF threshold required by regulatory agencies. High-performance liquid chromatography with electrospray ionization mass spectrometry (HPLC-ESI-MS) analysis identified 19 phenolic compounds, mainly flavonoids and chlorogenic acids, which likely account for these effects. Overall, the results highlight the potential of E. glomeratus as a promising source for the development of natural, effective, and environmentally sustainable photoprotective formulations.

Abstract in Portuguese:

The sweets from Pelotas, recognized as Brazilian heritage, preserve ancestral knowledge maintained by female confectioners. The ban on copper pans in production has sparked debate, as these utensils are believed to release excess copper into food. This study quantifies copper in sweets to support discussion on restrictions and gaps between ANVISA (Brazilian Health Regulatory Agency) regulations and scientific evidence. Five traditional sweets from Pelotas were analyzed, and copper concentration ranged from < limits of detection (LOD) of 0.140 to 25.97 mg kg-1. Among them, three had copper levels in sweets below ANVISA limit (10 mg kg-1), while two exceeded it. Even so, the latter concentrations were lower than those limits recommended by ANVISA to other foods such as nuts and coffee. In this context, these results raise questions about the true source of copper in sweets that exceeded the limit, as samples prepared in the same copper pans sometimes showed concentrations below the LOD, while others surpassed legal thresholds. This suggests copper may come from ingredients rather than pans. Thus, copper pans - already legalized for sweet production in states like Minas Gerais - may not be the “villain”, supporting the preservation of traditional sweet-making with appropriate safety measures.

Abstract in English:

Hydrogen sulfide is a toxic and corrosive gas that poses significant health, safety, and environmental risks in industrial operations, particularly in natural gas processing. In floating production storage and offloading (FPSO) platforms, iron oxide-based scavengers are commonly used to “sweeten” natural gas streams by removing H2S, thereby ensuring operational safety, preventing equipment corrosion, and enabling compliance with offshore environmental regulations. However, during their operational use, these scavengers can also adsorb hydrocarbons, which has implications for waste management and environmental safety. This study investigates the capacity of iron oxide-based scavengers (Fe2O3/Fe3O4) to retain aliphatic and polycyclic aromatic hydrocarbons, rather than focusing on H2S removal. Gas chromatography analysis revealed hydrocarbon retention levels of up to 62 mg kg-1 for aliphatic compounds and 32 mg kg-1 for PAHs (polycyclic aromatic hydrocarbons). These findings are critical for assessing the environmental risks associated with the final handling of spent scavengers and for guiding the development of appropriate end-of-life treatment strategies. A better understanding of hydrocarbon retention, including the types and amounts retained, contributes to safer and more sustainable management of these materials within offshore operations and informs the development of appropriate end-of-life treatment strategies.

Abstract in English:

Respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis remain critical global health challenges, necessitating the development of novel therapeutics targeting key airway receptors. This study employed structure-based virtual screening (SBVS) and molecular docking to investigate ligand interactions with beta-2 adrenergic receptors (β2-AR) and muscarinic acetylcholine receptors (mAChRs), pivotal regulators of bronchial tone and mucus secretion. Four high-resolution crystal structures of β2-AR (Protein Data Bank (PDB) IDs: 2RH1, 5D5A, 6PS2, 8GG0) and mAChRs (PDB IDs: 5CXV, 6OIJ, 6OL9, 6WJC) were prepared by removing non-protein moieties, optimizing protonation states, and energy minimization. Six clinically relevant ligands formoterol, ipratropium bromide, levalbuterol, propranolol, salbutamol, and tiotropium were energy-minimized and docked using GOLD (Genetic Optimization for Ligand Docking) software centered on active sites derived from co-crystallized ligands. Key interactions, including hydrogen bonds with conserved residues (e.g., β2-AR: Asp113, Ser203; mAChRs: Tyr506, Asn507), were identified using molecular docking analyses. Tiotropium and ipratropium bromide exhibited high binding affinities for mAChRs, aligning with their established anticholinergic efficacy. For β2-AR, long-acting agonists formoterol and salbutamol showed strong binding, consistent with their bronchodilatory roles. Propranolol, a β-blocker, displayed competitive antagonism at β2-AR, highlighting subtype selectivity challenges. These findings pave the way for optimizing dual-target ligands to address multifactorial respiratory pathologies while minimizing off-target effects.

Abstract in English:

Using waste polyethylene terephthalate (PET) as the feedstock, diisooctyl terephthalate (DOTP) was directly synthesized via alcoholysis with isooctanol (2-EH) over an environmentally friendly choline chloride-zinc acetate (the ChCl-Zn(Ac)2 catalyst)-deep eutectic solvent (DES). This approach overcame the limitations of traditional methods by offering simplicity, low cost, tunable composition, excellent environmental compatibility, and superior chemical stability. The study systematically investigated the effects of reaction temperature, catalyst dosage, molar ratio of 2-EH to PET, and reaction time on the synthesis process. Response surface methodology (RSM) was employed to optimize the process conditions, with the optimal parameters determined as follows: reaction temperature of 180 °C, catalyst dosage of 5.19%, molar ratio of 2-EH to PET of 4.89 mol mol-1, and reaction time of 87.30 min. Under these optimal conditions, PET was completely degraded, and the DOTP yield reached as high as 87.59%. The ChCl-Zn(Ac)2 catalyst exhibited stable performance, significantly enhanced both the PET degradation rate and the DOTP yield. This study provides a feasible technical solution for the efficient resource utilization of waste PET, offers a reference for developing green catalytic synthesis processes of DOTP, and expands the application potential of DES catalysts in polyester degradation.

Abstract in Portuguese:

PYROLYSIS AND CO-PYROLYSIS OF PEQUI AND BABASSU SHELLS: A SUSTAINABLE APPROACH TO RESIDUES UTILIZATION. The use of agro-industrial residues as biomass for clean energy production has received prominence in view of the major environmental challenges. This study focused on investigating the potential of pequi peel flours (PPF) and babassu (BPF) as feedstocks in the pyrolysis process, evaluating the influence of temperature and biomass ratio on the quality of volatiles and the synergistic effect. The PPF and BPF were characterized and subjected to pyrolysis in the PPF:BPF ratios (1:0; 0:1) and 1:1 (co-pyrolysis), at temperatures of 550 and 750 °C. The highest hydrocarbon content, 21.48%, was obtained in the pyrolysis of PPF at 550 °C, an interesting condition for biofuel production. Fine chemical compounds, such as furfural and 5-hydroxymethylfurfural (HMF), were detected in the chromatograms of PPF and BPF. Co-pyrolysis at 550 °C reduced the content of oxygenated compounds compared to PPF pyrolysis from 51.26 to 42.21%, and showed a synergistic effect in levoglucosan formation, a relevant compound to the polymer and pharmaceutical industries. Overall, the findings demonstrate that PPF and BPF are promising biomass feedstocks for pyrolysis, with potential applications in both renewable energy and high-value chemical production.

Abstract in English:

This study explores the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D), a common herbicide, using the Fenton oxidation process under varying conditions. A factorial design approach was applied to evaluate the impact of pH (2.50, 2.75, 3.00), FeSO4∙7H2O concentrations (0.3, 0.5, and 0.7 mmol L-1), and H2O2 concentrations (3.0, 5.0, and 7.0 mmol L-1), with a fixed 2,4-D concentration of 100 mg L-1. A total of 27 experiments were conducted to assess removal efficiency and post-treatment ecotoxicity. Optimal degradation was observed at pH 2.75, FeSO4∙7H2O = 0.3 mmol L-1, and H2O2 = 7.0 mmol L-1, achieving a 69.66% reduction in 2,4-D concentration after 120 min of treatment. The results indicate that the Fenton process is a viable pretreatment option for agrochemical wastewater, offering effective partial degradation and a reduction in toxicity. These findings support the potential of Fenton oxidation as an environmentally friendly approach for mitigating the impacts of herbicide-contaminated wastewater.

Abstract in English:

Fungal vaginitis is an inflammatory condition of the vaginal mucosa caused by fungal proliferation, characterized by symptoms such as pruritus, dysuria, and dyspareunia. Despite antifungal agents are widely used orally and topically, women report adverse effects including burning, hypersensitivity and irritation. In this context, this study proposes an alternative therapeutic approach using herbal medicine Jatropha mollissima, which exhibits pharmacological potential, ovules composed of chitosan, gelatin, and Jatropha mollissima ethanolic extract were developed, aiming to enhance antifungal treatment efficacy while minimizing side effects. Ovules were fabricated via lyophilization, using three different gelatin concentrations in a chitosan matrix. After determining the optimal concentration, ovules were formulated with 2% (w/v) chitosan in 1% (v/v) acetic acid, 15% (w/w) gelatin, and Jatropha mollissima extract at 1, 3, and 5% (w/w). Samples were characterized by optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, swelling degree, in vitro biodegradation, antimicrobial and antifungal activities, and cytotoxicity. The results confirmed porous structures, extract incorporation, complete degradation within 28 days, antimicrobial activity against E. coli and S. aureus, antifungal activity against C. albicans, and absence of cytotoxicity in L929 cells. This approach represents a significant advancement in the treatment of fungal vaginitis, offering therapeutic benefits with reduced side effects.

Abstract in Portuguese:

Plant species of the Piper genus are rich in essential oils and are known to exhibit significant antimicrobial and insecticidal activities. In this study, the leaves of Piper glabratum were collected in the city of Primavera, Pernambuco State, and their volatile profiles were determined by hydrodistillation and headspace microextraction. The chemical profile of the essential oil was rich in sesquiterpenes, and sesquiterpenoid italicene ether (34.4%) was identified as the major compound. The coumarin 7-isoprenyloxycoumarin (2.4%), a secondary metabolite rarely found in plant essential oils, was also identified. (E)-β-Ocimene (42.9%) and δ-3-carene (40.1%) were the major volatiles identified in the headspace microextraction. The essential oil of P. glabratum exhibited antimicrobial activity against the bacteria Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae, being most active against E. faecalis, with minimum inhibitory concentration and minimum bactericidal concentration values of 1024 and 2048 μg mL-1, respectively. This paper is the first report of antibacterial activity for the essential oil of P. glabratum leaves, as well as the first report of the occurrence of the species in the state of Pernambuco.

Abstract in English:

Oxandra martiana is an unexplored Annonaceae species with a geographic distribution restricted to southeastern Brazil. The essential oil obtained from the leaves by hydrodistillation yielded 0.32% and was characterized by epizonarene (41.88-48.24%) as the major component, followed by viridiflorene (6.71-7.98%), (Z)-β-ocimene (4.56-7.05%), and δ-cadinene (4.91 5.43%). The antibacterial activity of the essential oil was evaluated against clinically relevant Gram-positive and Gram-negative strains. The minimum inhibitory concentration (MIC) assays revealed that the oil inhibited the growth of Staphylococcus aureus and Staphylococcus epidermidis at 2 mg mL-1, while no inhibitory effect was observed against Escherichia coli (> 2 mg mL-1). Minimum bactericidal concentration (MBC) analysis indicated a bactericidal effect exclusively against S. aureus (2 mg mL-1). These findings suggest a selective antibacterial potential of O. martiana essential oil, particularly against Gram-positive bacteria, due to differences in cell wall structure and permeability. This study provides the first chemical and antibacterial report of O. martiana leaf essential oil, highlighting its selective activity against Gram-positive bacteria. Further studies are needed to explore the phytochemical diversity of the genus Oxandra and to assess its potential for pharmaceutical and biotechnological applications.

Abstract in English:

O-Carboxymethyl chitosan is a chitosan derivative with potential for the development of biocompatible nanotechnological systems. This study aimed to develop and evaluate a topical formulation containing O-carboxymethyl chitosan nanoparticles associated with vitamin C and Carbopol® 940, focusing on its stability and biocompatibility. The nanoparticles were prepared with 5% vitamin C in an aqueous solution of O-carboxymethyl chitosan (0.25% w/w) and different concentrations (1, 2, and 3%) of Carbopol® 940. The formulations were characterized by FTIR (Fourier transform infrared spectroscopy), DLS (dynamic light scattering), zeta potential, polydispersity index (PDI), UV-Vis, and rheological behavior, in addition to a cytotoxicity assay in L929 cell line. The nanoparticles showed an average size of 357.28 ± 10.85 nm, zeta potential of -3.19 ± 0.85 mV, and PDI of 0.241 ± 0.055, maintaining stability for up to 90 days at 25 °C. The formulations exhibited pseudoplastic behavior, good injectability, and no physicochemical interaction between the polymer and vitamin C. The cytotoxicity assay confirmed the biocompatibility of the formulation. The results indicate that O-carboxymethyl chitosan is a promising polymer for nanoengineered systems containing vitamin C in topical formulations.

Abstract in English:

This work presents three theoretical functions for obtaining nanoscale CO2 adsorption data on a dehydrated NaX zeolite reported in the literature at temperature (T) = 298 K, pressure (p) = 1 bar, ratio SiAl-1 = 1, BET equivalent area (SBET) = 652 m2 g-1, pore total volume (Vmp) = 0.43 cm3 g-1 and saturation capacity approximately 6.27 mmol g-1. From BET and Vmp, the theoretical monolayer capacity at 10 mmol g-1 was derived. Results indicate that the CO2 experimental saturation corresponds to 60% of the monolayer, reflecting the partial accessibility of adsorption sites. The analysis of the average density at this loading shows value approximately 0.65 g cm-3, finding a reasonable parallel of molecular packing inside BET pore comparable to saturated liquid state of CO2, 0.77 g cm-3 at 298 K, p = 65 bar. The benchmark points to values around 3.0-3.5 g cm-3 that corresponds to a forced solid state of CO2 obtained under high pressure. Therefore, this methodology supports the plausible interpretation of adsorbate-adsorbate of packing density at 114 ± 8.1 Å3 molecule-1. It was estimated in 6.55 the number of strong-active sites per α-cavity in cell of NaX and occupation of 1.62 CO2 molecules per adsorption sites in co-adsorption process.

Abstract in English:

The main objective of this study was to evaluate the composition and antioxidant activity of compounds present in the pulp and seeds of acerola (Malpighia emarginata DC.), with a view to the sustainable use of agro-industrial by-products. The samples were prepared and analyzed by ultra high performance liquid chromatography with mass spectrometry (UHPLC-MS/MS) to identify and quantify phenolic compounds and flavonoids, and were also subjected to different methods of antioxidant activity assessment, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and oxygen radical absorbance capacity (ORAC). The analysis revealed a greater diversity and concentration of bioactive compounds in the seed, highlighting the exclusive presence of ferulic acid, detection of rutin in both fractions, and chlorogenic acid only in the pulp. The results indicate that the seed has greater antioxidant potential and total phenolic content compared to the pulp, evidencing its nutritional value. The study reinforces the potential of acerola seeds as a possible application in functional foods and value-added products, contributing to the valorization of agro-industrial waste.

Abstract in English:

Feminine intimate hygiene requires formulations capable of reducing microbial load while maintaining physiological compatibility with the vulvovaginal environment. In this study, carboxymethyl chitosan (CMQ) solutions containing Jatropha mollissima extract were developed and characterized to assess their potential for external intimate hygiene applications. Formulations containing 1 3% (m/v) CMQ and 10% (m/m) extract were evaluated through organoleptic, physicochemical, rheological, and biological analyses. The incorporation of J. mollissima modified the coloration of the solutions without altering odor or compromising formulation homogeneity. The systems exhibited near neutral pH and pseudoplastic flow behavior, with viscosity decreasing under shear properties favorable for controlled spreading and retention at the application site. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the preservation of phenolic and terpenoid functional groups, while injectability tests demonstrated extrusion forces comparable to commercial references. Cytotoxicity assays (ISO 10993 5) indicated grade 0 reactivity, and antimicrobial tests showed concentration dependent inhibition against Escherichia coli, Staphylococcus aureus, and Candida albicans. Although inhibition halos were modest, they were consistent with non pharmacological topical applications. Together, the results highlight the functional and biological suitability of CMQ/J. mollissima systems for external feminine hygiene, while also indicating the need for future optimization regarding pH adjustment, surfactant selection, extract standardization, and stability evaluation.

Abstract in English:

The essential oil (EO) of Varronia dardani (Taroda) J.S. Mill (Cordiaceae), a plant widely distributed in northeastern Brazil, was analyzed for its chemical profile and evaluated for its antifungal, antibacterial, and insecticidal activities. The EO was obtained by hydrodistillation and analyzed by gas chromatography coupled to a mass spectrometer (GC-MS) and gas chromatography with a flame ionization detector (GC-FID). Limonene (27.49%) and dehydro-1,8-cineole (13.23%) were identified as the major constituents. The EO exhibited strong bactericidal activity, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 1.5 mg mL−1 against Staphylococcus aureus and 200 mg mL−1 against Escherichia coli, and Pseudomonas aeruginosa. For Candida albicans and Candida parapsilosis, the MIC was 48 mg mL−1, indicating a fungistatic effect. In larvicidal assays, the EO showed LC50 and LC90 (lethal concentrations required to kill 50 and 90% of the larvae) values of 1.20 and 2.57 mg mL−1 after 1 h, which decreased to 0.92 and 1.92 mg mL−1 after 2 h. These findings demonstrate that EO is a promising natural antimicrobial agent and an effective larvicide against A. aegypti larvae.

Abstract in English:

Succinic acid is a platform chemical widely used in the pharmaceutical, food, and materials industries, exhibiting notable polymorphic behavior that directly impacts its physicochemical properties. Succinic acid presents three reported crystal polymorphs, of which the γ-form is the least common and typically arises under specific non-equilibrium conditions. This study reports, for the first time, the isolation and crystallization of the γ-polymorph of succinic acid from a plant matrix (Solanum sanctae-catharinae Dunal). The crystalline compound was obtained from the ethyl acetate fraction following column chromatography. Structural characterization by single-crystal X-ray diffraction (SC-XRD) allowed the unambiguous assignment of the crystalline phase as the γ-polymorph through comparison with previously reported crystallographic data. The formation of the γ-polymorph under mild conditions suggests that the chemical complexity of the plant matrix may have influenced the crystallization pathway, possibly acting as a molecular template. This study contributes to expanding the literature of S. sanctae-catharinae and disclose new possibilities for the study of crystals polymorphism in natural matrices.

Abstract in Portuguese:

A theoretical study based on B3PW91/aug-cc-pVTZ (Becke, 3-parameter, Perdew-Wang 91/augmented correlation-consistent valence triple-zeta) density functional calculations and the topology of the quantum theory of atoms in molecules were used for unveiling the formation of intermolecular interactions between 3-chloro-1-propene and sodium fluoride. In the vision of structural parameters, the intermolecular distances and the bonds lengthening and shortening associated with the vibrational stretch modes represented by the shifting frequencies and absorption intensity ratios were used for discussing the features of the F∙∙∙H hydrogen bonds, Cl∙∙∙Na alkali-halogen and Cl∙∙∙C halogen-carbon interactions. The great aims were focused on C3H5Cl∙∙∙NaF bimolecular structure and C3H5Cl∙∙∙2NaF trimolecular form, wherein this last contains a chlorine atom that forms simultaneously a binary Cl∙∙∙Na interaction followed by a directional Cl∙∙∙C type, and evidently the F∙∙∙H hydrogen bonds already existing.

Abstract in Portuguese:

Starch-based bioplastics, incorporating different amounts of malt bagasse as a plant-based filler and glycerol as a plasticizer, were developed and characterized in terms of their physical and mechanical properties. Four bagasse samples, varying in condition and particle size, were used in the preparation of the materials, along with four glycerol concentrations (10, 20, 30, and 40% m/m ) per formulation. The bioplastics were produced by solution casting and analyzed using optical microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis, in addition to the evaluation of physical properties (density, thickness, grammage) and mechanical properties (tensile strength, % elongation at break, and Young’s modulus). The incorporation of bagasse influenced structural properties, reducing density and Young’s modulus in some formulations. Results showed that materials with 30 and 40% glycerol exhibited greater flexibility, while those with 10 and 20% resulted in more rigid bioplastics. This effect was maintained even after the addition of malt bagasse. These findings highlight the potential of brewing industry residues for the production of biodegradable materials, contributing to sustainability and circular economy initiatives.

Abstract in English:

The granulometric analysis and chemical composition highlight intrinsic challenges for flotation. The predominance of ultrafine particles generates slimes that reduce selectivity, while the high proportion of silica and alumina introduces gangue phases that compete with hematite for collector adsorption. These features justify the need for collectors capable of strong and selective adsorption under adverse particle-size conditions, providing the rationale for testing reagents with different molecular structures in microflotation assays. The results demonstrated that saponified palm (SPO) and saponified soybean oils (SSO) exhibit effective collecting ability under alkaline conditions, achieving iron recoveries comparable to sodium oleate. Collector dosage and pH were identified as the most influential parameters, with interaction effects defining operating windows for maximizing selectivity and metallurgical recovery. Surface chemistry analyses further indicated that the fatty acid composition and degree of saponification strongly affected adsorption efficiency at the hematite interface. These findings confirm that vegetable-oil-derived soaps can function as technically viable and environmentally benign collectors. The study highlights the potential of SPO and SSO to replace conventional surfactants and demonstrates the usefulness of response-surface methodology (RSM) as a tool for optimizing bio-based flotation reagents, contributing to greener mineral processing technologies.

Abstract in English:

This study investigates the functionalization of silica gel, derived from renewable sources of rice husks, functionalized with silver (Ag) and zinc oxide (ZnO) nanoparticles for use in antimicrobial absorbent pads intended for active meat packaging applications. Silica matrices were synthesized and subsequently decorated with Ag through chemical reduction and ZnO through precipitation methods. A comprehensive characterization was performed to evaluate metal loading efficiency, leaching behavior in aqueous media, and antimicrobial activity against Pseudomonas aeruginosa, a Gram-negative bacterium associated with spoilage. Agar diffusion and minimum inhibitory concentration (MIC) tests revealed that Ag-functionalized silica exhibited significant antimicrobial efficacy, with MIC values ranging from 15 to 21 µg mL-1. In contrast, ZnO-functionalized silica demonstrated negligible inhibition, attributed to the known zinc homeostasis mechanisms of P. aeruginosa. The application of functionalized silica in absorbent pads significantly reduced bacterial counts during refrigerated storage of beef samples for 96 h, particularly with Ag-SiO2. These findings highlight the potential of Ag-based nanostructures supported on silica gel as effective antimicrobial components for sustainable active food packaging.

Abstract in English:

This article employs terahertz time-domain spectroscopy (THz-TDS) to measure the terahertz absorption spectra of benzoic acid and anisic acid within the frequency range of 0.6-2.4 THz. Simultaneously, under the framework of density functional theory (DFT), the B3LYP-D3 method and the M06-2X method were utilized to conduct theoretical calculations on these two substances. Following a comparative analysis, it was found that the calculated results obtained through the B3LYP-D3 method exhibited a higher degree of consistency with the experimental results. To elucidate the formation mechanism of the absorption peaks in detail, the potential energy distribution (PED) method was employed to assign the corresponding vibration modes. The assignment results reveal that the characteristic peaks in the terahertz spectra of these two substances primarily stem from bond angle bending and dihedral angle torsion. Moreover, a qualitative and quantitative analysis of intermolecular weak interactions was carried out using the interaction region indicator (IRI), energy decomposition analysis based on force-field (EDA-FF), and in conjunction with the electrostatic potential (ESP) methods. This study reveals the intrinsic relationship between terahertz spectral differences and weak intermolecular interactions, providing important insights for a deeper understanding of the internal structural characteristics and potential applications of material molecules.

Abstract in Portuguese:

Mesoporous silica particles were obtained using the sol-gel method, based on hydrolysis and condensation reactions of alkoxides. This technique enables the production of powders with high purity and chemical homogeneity at low temperatures and reduced costs. Silica was chosen for its biocompatibility and absence of contamination risk. Its versatile structure allows modifications that expand its applications in catalysis, chromatography, luminescent materials, and controlled drug release. The main objective of this study was to obtain mesoporous silica particles from the tetraethyl orthosilicate (TEOS) alkoxide precursor in a basic medium, varying the concentration of the surfactant cetyltrimethylammonium bromide (CTAB), giving rise to the S1 and S2 samples, with lower and higher surfactant concentrations, respectively. These particles were then modified with silver nanoparticles (AgNPs), synthesized by reducing silver nitrate using sodium borohydride as a reducing agent. The obtained materials were characterized by vibrational infrared spectroscopy, where bands at 3740, 3540, and 948 cm-1 were observed, associated with silanol groups (Si-OH). Bands at 1089, 803, and 450 cm-1 correspond to Si-O-Si bond vibrations. X-ray diffraction confirmed the presence of a halo at approximately 22° in 2θ, indicating that the synthesized mesoporous silica does not exhibit an ordered crystalline structure. Ultraviolet-visible absorption spectroscopy confirmed the formation and incorporation of silver nanoparticles with the presence of a band around 400 nm. Dynamic light scattering analysis showed hydrodynamic radii ranging from 400 to 600 nm, and zeta potential analysis indicated a negative surface charge below -30 mV, characterizing the sample as unstable. Microbiological analyses against Escherichia coli and Staphylococcus aureus bacteria revealed that at a concentration of 2000 µg mL-1, the S2, S2 + 1 mgAgNPs, and S2 + 5 mgAgNPs samples exhibited bactericidal properties, while at 1000 µg mL-1, the S2 + 10 mgAgNPs sample demonstrated bactericidal activity against S. aureus, indicating microorganism death.

Abstract in English:

The development of topical systems for the controlled release of cannabidiol (CBD) is a pharmacotechnical challenge due to its lipophilicity and low aqueous solubility. This study aimed to develop and characterize polymeric films of hydroxypropylmethylcellulose (HPMC) and α-gluco-oligosaccharide (α-GOS) containing CBD, prepared by the solvent casting method in different HPMC:α-GOS ratios (100:0, 80:20, 60:40, and 40:60), with and without 1% CBD. The analyses included macroscopic evaluation, thickness, average weight, mechanical properties, water vapor transmission, degradation index, solubility, as well as Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that α-GOS significantly increased hydrophilicity, enhancing solubility and degradation, while CBD increased thickness without compromising thermal stability. Films with higher HPMC content exhibited greater mechanical strength, and FTIR confirmed the absence of relevant chemical interactions. Thermal analyses indicated stability up to approximately 195 and 239 °C, and SEM images revealed homogeneous surfaces in HPMC-rich films, rougher surfaces with α-GOS, and emulsified particles upon CBD addition. It is concluded that the method employed was suitable and that intermediate formulations (60:40 and 80:20) presented the most promising properties for topical application.

Abstract in Portuguese:

In this work we demonstrate the high potentiality of polyaniline or polyaniline/carbon nanotubes thin films as selective and reliable optical pH sensors. The films were prepared based on the liquid/liquid interfacial route, deposited over glass or quartz planar substrates, and characterized by UV-Vis, Raman and Fourier transform infrared spectroscopy (FTIR), as well as scanning electron microscopy. The polyaniline was obtained in its green and conductive structure, salt emeraldine, which is converted to the blue emeraldine base in alkaline condition. The color sensitivity of the film is easily followed by UV Vis spectroscopy, allowing the elaboration of different analytical curves in a broad pH range (2 to 12). Sensor performance tests demonstrated high sensitivity (0.08394 A/pH) and excellent performance at higher pHs, with detectable pH variations in very narrow ranges, as well as excellent repeatability and reproducibility, essential for continuous industrial applications.

Abstract in English:

The microalgae Chlorella is known for its high photosynthetic capacity and rich nutritional profile. This study analyzed the fatty acid composition of twenty brands of Chlorella supplements available in the Brazilian market. The results revealed significant differences. Palmitic acid (16:0) exhibited the highest concentrations in samples 8 and 9. In contrast, samples 4, 13, 17 and 19 presented lower levels of palmitic acid. The concentration of linoleic acid (18:2n-6) peaked at 19.67 mg in sample 12, while sample 19 recorded the lowest level of 3.9 mg. Alpha-linolenic acid (18:3n-3) was the most abundant. Antioxidant capacity was evaluated using 2,2-diphenyl-1 picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The results showed varying levels of free radical scavenging, with sample 4 exhibiting the highest values in ABTS (319.17 ± 16.57 µmol Trolox equivalents (TE) g-1) and DPPH (525.43 ± 24.04 µmol TE g-1) assays, followed by samples 19 and 12. Mineral analysis revealed significant variations in iron and zinc concentrations among samples. Iron content ranged from 49.8 to 770 mg 100 g-1, and zinc concentrations ranged from 2.38 to 12.2 mg 100 g-1. These findings highlight the nutritional value of Chlorella as a supplement, offering antioxidant protection and essential minerals that may aid in the prevention of chronic diseases.

Abstract in English:

This study investigates the influence of copper oxide (CuO) microparticles with different morphologies on the structural, mechanical, and antimicrobial properties of polyvinyl alcohol (PVA) biofilms. CuO microparticles were synthesized via a simple co-precipitation method under controlled pH and thermal conditions, yielding fibrous, granular, and spherical morphologies. The particles were physically dispersed into the PVA matrix at different weight ratios using the casting method. The resulting composites were characterized by X-ray diffraction (XRD) with Rietveld refinement, dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), mechanical testing, and microbiological assays. The results demonstrate that both particle morphology and concentration significantly affect film crystallinity, Young’s modulus, and tensile strength. Fibrous CuO microparticles enhanced surface antimicrobial activity, producing larger inhibition zones against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923, whereas spherical particles exhibited superior bactericidal performance in liquid culture due to improved dispersion and sustained Cu2+ ion release. Despite the absence of particle functionalization, which may have limited interfacial interactions, the composites exhibited promising multifunctional performance. These findings highlight the critical role of particle shape, distribution, and interfacial quality in tailoring the properties of PVA/CuO biofilms.

Abstract in English:

Feathers from poultry waste, composed of approximately 90% keratin, represent an environmental burden but also a valuable source of biopolymers. This study assessed keratin extraction via a chemical reduction method. Two protocols were used: Ke-1, employing urea and sodium sulfite at pH 7 under reflux at 75 °C for 10 h, and Ke-2, which incorporated sodium dodecyl sulfate (SDS) at pH 9 for 4 h. After dialysis and lyophilization, the yields were 70% (Ke-1) and 78% (Ke-2). Fourier transform infrared spectroscopy (FTIR) spectra showed characteristic bands (amide A, I, II, III), confirming α-helix and β-sheet secondary structures. X-ray diffraction (XRD) analysis exhibited peaks at 19.03° (Ke-1) and 19.51° (Ke-2), indicating the predominance of β-sheets. Thermogravimetric analysis (TGA) revealed two thermal events: dehydration near 100 °C and degradation of the α and β structures of keratin between 240-400 °C. Micrographs obtained by scanning electron microscopy (SEM) indicated fibrillar morphology with hollow cavities, with Ke-2 displaying larger fiber diameters. The 1H nuclear magnetic ressonance (NMR) spectrum confirmed signals from amino, carboxyl, methyl, and methylene groups, associated with amino acid residues of keratin. Notably, Ke-2 exhibited dose-dependent bacteriostatic activity against Staphylococcus aureus. This study demonstrates the valorization and reuse of organic residues derived from the poultry industry through an efficient and scalable processing method for converting poultry waste into high-value keratin with promising biomedical and antimicrobial applications.

Abstract in English:

In this study, a mild and facile method for the synthesis of 3-indolyl azo derivatives using indole derivatives, aniline and tert-butyl nitro compounds at room temperature was developed. The optimum conditions of anhydrous ethanol as solvent and tetrabutylammonium iodide (TBAI) as catalyst were determined by systematic screening of the reaction conditions, which gave up to 77% yield. It was also found that the electronic nature of the aniline substituent, the structure of the N-1 substituent of the indole framework and the side chain substituents significantly affected the reaction efficiency. The method has good functional group tolerance, provides a new route for the synthesis of 3-indolyl azo compounds, and demonstrates good synthetic utility in scale-up experiments.

Abstract in English:

Brazil nuts (Bertholletia excelsa) and cashew nuts (Anacardium occidentale) are important dietary sources of essential minerals. However, the total concentration of an element does not necessarily reflect the fraction absorbed by the human body, making it crucial to evaluate the amount of nutrients that becomes available upon ingestion. This study quantified the total and bioaccessible concentrations of Cu, Mg, Mn, and Zn in these nuts using an in vitro gastrointestinal digestion model followed by detection via inductively coupled plasma optical emission spectrometry (ICP OES). The results revealed high total concentrations of these minerals in all samples. However, when assessing bioaccessibility, only Cu and Mg were released after the in vitro assay, while Mn and Zn were below the limit of detection. The nutritional contributions per serving were significant: a 30 g portion of cashew nuts provided 38.0% (Cu) and 9.9-12.8% (Mg) of the recommended daily intakes (RDI), while a 15 g portion of Brazil nuts provided 18.0% (Cu) and 4.8-6.1% (Mg). The contrast between total contents and bioaccessible fractions highlights the influence of antinutritional factors in limiting mineral utilization. These findings imply that: (i) nutritional labeling should consider bioaccessibility data, and (ii) processing methods that reduce antinutrient content may enhance mineral bioavailability.

Abstract in English:

This is the first study to investigate the photothermal effect of silver nanoparticles (AgNPs) encapsulated with the polysaccharide galactomannan (GAP), synthesized from the aqueous extract of Adenanthera pavonina seeds. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and ultraviolet-visible (UV-Vis) absorption spectroscopy. The UV-Vis absorption spectra showed an increase in the absorption band around 425 nm, indicating the presence of AgNPs. The average particle size was 9.61 ± 5.0 nm. The photothermal performance was evaluated under infrared radiation using a near-infrared (NIR) laser with a wavelength of 850 nm. It was observed that AgNPs encapsulated with a higher concentration of GAP polysaccharides exhibited a significant temperature increase, reaching a temperature variation (∆T) of approximately 40 °C. Furthermore, they demonstrated excellent photothermal stability over repeated cycles, indicating their potential as photothermal agents.

Abstract in Portuguese:

Based on National Agency of Petroleum, Natural Gas and Biofuels (ANP) Resolution No. 696, the limit of methanol content in ethanol anhydrous fuel and ethanol hydrated fuel is 0.5% v/v. Despite this, unfortunately what has been seen in the field is this rampant adulteration in some places. The adulteration of methanol in ethanol is harmful to society and ends up being carried out due to the lower value of the methanol compared to ethanol. This illegal use can cause high consumption in the automotives and injuries to human health (notably gas station attendants and mechanics), environmental damage and tax evasion. This analysis cannot be determined using the current quality testing equipment determined by ANP, since they are not sufficient for this on-site analysis. Therefore, it was used the Cary 630 Fourier transformed infrared spectroscopy (FTIR) allied to partial least squares (PLS) to quantify methanol in ethanol fuels with: root mean square error of calibration (RMSEC), root mean square error of cross validation (RMSECV) and root mean square error of prediction (RMSEP) values of 0.2% v/v, 0.2% v/v and 0.2% v/v, respectively. The method can be extremely helpful to technical experts to quickly obtain a preliminary result outside the laboratory, in less than ten seconds, allowing a rapid decision by public agency and companies if the methanol content in the sample is outside the acceptable limit.

Abstract in English:

An autochthonous inoculum was developed using sugarcane bagasse (SCB) as the sole source of microorganisms in anaerobic reactors containing yeast extract (2.0 g L-1) and pentose liquor (3 g COD L-1, where COD: chemical oxygen demand), with the initial pH adjusted to 6.5. This inoculum was applied to evaluate the individual and interactive effects of SCB concentration (1.6 8.4 g L-1), pentose liquor concentration (0.4-4.4 g COD L-1), obtained from the hydrothermal pretreatment of SCB at 190 °C for 10 min, and initial pH (5.2-6.8) on biological hydrogen (H2) production. Statistical optimization tools were employed to identify optimal operational conditions. H2 production reached up to 126.82 mL under the evaluated conditions, while carbohydrate utilization efficiencies ranged from 38 to 76%. According to the statistical optimization, maximum H2 production (179.43 mL) was achieved at 1.5 g L-1 SCB, 4.7 g COD L-1 pentose liquor, and an initial pH of 6.8, accompanied by the formation of butyric (1,250 mg L-1), acetic (840 mg L-1), and lactic acids (425 mg L-1). The relatively low SCB loading may have reduced the impact of inhibitory compounds commonly present in lignocellulosic hydrolysates. These results demonstrate the effectiveness of process optimization in enhancing fermentative H2 production from sugarcane-derived substrates.

Abstract in Portuguese:

This study aimed to perform ultrasound-assisted extraction (UAE) of the leaves, flowers, fruits, and leaf-fruits of Pereskia aculeata Miller and to incorporate the resulting extracts into poly(vinyl alcohol) (PVA) nanofibers via electrospinning. The extraction was carried out using a 70% (v/v) hydroalcoholic ethanol solution as the solvent, under 20 kHz frequency and 750 W power for 5 min. The extracts were evaluated for yield, total phenolic content, antioxidant activity, and antimicrobial activity against Staphylococcus aureus and Escherichia coli. Nanofibers were produced using a PVA solution at 8% (m/v) and 1% (m/v) of extract, under an applied voltage of 15 kV, a flow rate of 0.5 mL h-1, 200 rpm rotation, and a needle to collector distance of 15 cm. The formulations were characterized by scanning electron microscopy (SEM), thermogravimetry analysis (TGA), Fourier transform infrared spectroscopy (FTIR), mechanical testing, and antioxidant and antimicrobial activity assays. The results indicated that nanofibers containing leaf extract showed the best overall performance, with well-distributed fibers, uniform diameters (381.55 ± 94.54 nm), high thermal stability, and prominent antioxidant activity, attributed to the higher total phenolic content. The nanofibers functionalized with P. aculeata extracts exhibited antimicrobial effects without compromising fiber morphology, highlighting their potential innovative for application in bioactive wound dressings with controlled release properties.

Abstract in Portuguese:

This study aimed to perform an integrated assessment of the environmental sustainability and practical applicability of a microwave-assisted acid digestion method followed by inductively coupled plasma mass spectrometry for the determination of rare earth elements in Amazonian sediments. Environmental sustainability was evaluated using the analytical greenness metric, which measures compliance with the principles of Green Analytical Chemistry, while operational feasibility was assessed using the blue applicability grade index. The procedure demonstrated robust analytical performance, with recoveries between 95.1 and 103.5% and normalized error values below 1, confirming metrological reliability. The sustainability score of 0.52 indicated moderate environmental performance, mainly influenced by the use of concentrated mineral acids and energy consumption during digestion. In contrast, the applicability index of 7.25 classified the method as highly applicable, reflecting multielement capability, instrumental robustness, and regulatory acceptance. The results show that environmental sustainability and practical applicability are not directly proportional and should be evaluated jointly. This integrated approach provides a comprehensive framework for selecting analytical methodologies for complex environmental matrices.

Abstract in Portuguese:

Many of the toxins produced by cyanobacteria have multiple variants, some being more toxic than others. Microcystins are a group of toxins produced by cyanobacteria that have approximately 100 variants with LD50 (lethal dose 50%) values ranging from 25 to 1000 μg kg-1. The main target of microcystins in the human body is the liver. A concentration of 1.0 μM microcystin-LR, the toxin studied in this work, can produce threefold greater phosphorylation of cytokeratins in rat hepatocytes. A mixture of toxins from the microcystin class and originating from cyanobacteria was separated by the technique of high-performance liquid chromatography - online solid phase extraction (HPLC-SPE) in order to analyze the most toxic variant of them, microcystin-LR. The study consisted of investigating the inactivation of this toxin by gamma irradiation. For this purpose, microcystin-LR was irradiated with Cs137 source with varying doses of 1.0 to 8.0 kGy. The techniques of HPLC-SPE and mass spectrometry with triple quadrupole analyzer and electron spray ionization (ESI) system were used to study the effects of this inactivation by irradiation. Among the results it was demonstrated that the 1.0 kGy dosage was not sufficient to reduce the concentration of microcystin-LR below the maximum allowed value established by Brazilian legislation.

Abstract in English:

Simaba Aubl. underwent major taxonomic revision in the past decade and is comprised of eight accepted species. Quassinoids are triterpenoid markers for the Simaroubaceae that are found in half of Simaba spp. Simaba pubicarpa is a recently described tree found in terra firme Amazon rainforest. The aim of this work was to isolate and characterize the major constituents in S. pubicarpa leaf and branch extracts and evaluate their in vitro activity against the chloroquine-resistant K1 strain of the malaria parasite Plasmodium falciparum. Chromatographic techniques, including column chromatography and semi-preparative high-performance liquid chromatography (HPLC), were employed to isolate eleven natural products, which were identified by nuclear magnetic resonance (NMR), mass spectrometry, and comparison with the literature as: the tirucallane triterpenes niloticin (1) and piscidinol A (2); the alkaloid 9-methoxycanthin-6-one (3); the benzoic acid derivatives p-salicylic acid (4), vanillic acid (5) and methyl gallate (6); and the flavonoids epicatechin (7), afzelin (8), quercitrin (9), isovitexin (10) and vitexin (11). As in a previous study on S. pubicarpa, quassinoids were not isolated. Compounds 4 and 7-11 are reported for the first time in the genus Simaba. Wood and bark extracts (half-maximal inhibitory concentration (IC50) = 5.0-5.7 μg mL-1) and afzelin (IC50 = 8.9 μM) were active against P. falciparum.

Abstract in English:

Varicose ulcers represent a severe manifestation of chronic venous insufficiency and remain a major public health challenge. In this study, chitosan-based dressings incorporating Jatropha mollissima extract (1-5% m/m) were developed via lyophilization to enhance healing performance. The membranes exhibited a predominantly fibrous morphology with high swelling capacity, approximately 1600% for pure chitosan, with a progressive reduction upon extract incorporation, indicating a decrease in hydrophilicity and increase in network density. Fourier transform infrared spectroscopy (FTIR) analysis revealed intensified bands associated with O-H and N-H groups, suggesting hydrogen bonding interactions between chitosan and phenolic compounds of the extract. Thermogravimetric analysis showed improved thermal stability, with reduced mass loss in extract-loaded membranes (ca. 50-60%) compared to pure chitosan. Biodegradation assays demonstrated a decrease in mass loss from 73.43 (M) to 65.00% (MJ5) after 21 days in phosphate salt (PBS), indicating enhanced structural stability. All samples exhibited no cytotoxicity toward L929 fibroblasts. These results demonstrate that the incorporation of J. mollissima modulates physicochemical properties through intermolecular interactions, leading to reduced swelling, controlled degradation, and improved stability. The study highlights the novelty of combining chitosan with a Caatinga-derived bioactive extract to produce multifunctional membranes with tunable physicochemical and biological properties, although further studies are required to confirm their suitability for biomedical applications.

Abstract in English:

Energy from renewable sources, such as green hydrogen, stands out as an alternative with high potential to meet the significant global energy demand. New materials are being developed for use in catalytic hydrogen photogeneration. However, few works report precise control of the composition and structure of nanoparticles and their effects on water decomposition. The active sites available in both the semiconductor and the adsorbed nanoparticles significantly improve light absorption and reduce electron/vacancy pair recombination. Here, hydrogen was produced using TiO2 nanotubes decorated with plasmonic bimetallic nanoparticles. The samples were characterized by Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma optical emission spectrometer (ICP OES), X-ray excited photoelectron spectroscopy (XPS), UV-Vis, and N2 adsorption-desorption. The TEM images showed the formation of nanotubes with an external diameter of about 55 nm, with anatase being the predominant phase. The photocatalysts generally showed high production rates, particularly for AuPd-TiO2, with a rate of around 4000 μmol g-1. The results of this work show that the material is a good option for producing clean energy, providing future solutions for sustainable development.

Abstract in Portuguese:

Durvillaea antarctica is a brown macroalga of significant economic and biotechnological importance in Chile, notable for its composition of valuable biopolymers such as alginate and fucoidan, in addition to essential minerals and unsaturated fatty acids. This study aimed to optimize the alginate extraction method using a full-factorial design to maximize polysaccharide yield. The macroalgae and its extracts were characterized using established analytical techniques, including Kjeldahl (protein), Bligh and Dyer (lipids), gravimetry (ash and moisture), Fourier transform infrared spectroscopy (FTIR), and chromatography. The results demonstrated an alginate extraction yield of 40.9% with a mannuronic-to-guluronic acid ratio (M/G) of 4.57 under optimized conditions, highlighting the efficiency of the established protocol. The presence of omega-3 and omega-6 fatty acids, as well as Fe, Na, and K, was confirmed, together with a low lipid content (0.74%). FTIR and NMR (nuclear magnetic resonance) analyses indicated the successful extraction of alginate and fucoidan, with spectral features consistent with those reported in the literature for these biopolymers, confirming their spectroscopic compatibility rather than strict analytical identity. Overall, this work reinforces the potential of D. antarctica as a sustainable source of high-value compounds and provides a reproducible approach for efficient alginate extraction.

Abstract in Portuguese:

Scopoletin (Sco) is a natural coumarin compound with potent antioxidant activity; however, its poor aqueous solubility and low bioavailability significantly limit its clinical application. In this study, on the basis of density functional theory (DFT), the electronic structural characteristics of Sco were systematically analyzed via the B3LYP-D3BJ/6-311G(d,p) method. With chloromethyl-functionalized single-walled carbon nanotubes (SWCNTs (5,0)-CH2Cl) as the carrier, the adsorption interaction model between Sco and the carrier was optimized in combination with the solvation model based on density (SMD). The results of the theoretical analysis reveal that Sco forms a coplanar large π-conjugated system between its benzene ring and pyrone ring; O14-H22 and C1=O11 are identified as the key active sites of Sco; and the frontier molecular orbital (FMO) energy gap of Sco is 4.17 eV, which endows the molecule with both reactivity and chemical stability. In the adsorption interaction model, Sco is adsorbed onto the carrier surface via the synergistic effect of van der Waals forces and π-π stacking, with an adsorption energy of 0.56 eV, corresponding to exothermic physical adsorption. The charge-transfer amount is only 0.0128 e, which can prevent structural distortion of the drug molecule. After adsorption, the energy gap of the system narrows to 1.55 eV, with a considerable increase in electrical conductivity, and the electronic structure related to the core activity of Sco remains unchanged. This study theoretically elucidated the fundamental electronic structure of Sco and its interaction characteristics with functionalized carbon nanotubes (f-CNTs).

Abstract in Portuguese:

Adsorption is a fundamental phenomenon in various fields, from environmental remediation to energy and catalysis; however, the common use of linear regression for data modeling carries the risks inaccurate results. This study developed and validated an Excel 365 spreadsheet, called ADSORB-XL, for nonlinear regression analysis of adsorptive systems. The study focused on methylene blue removal using two adsorbent materials (activated carbons and seed-derived biochars). Kinetic models and adsorption isotherms were fitted using Gauss-Newton algorithm based on least squares method. The obtained results were systematically compared against four well-established scientific computing platforms: RStudio (R statistical environment), Jupyter Notebook (Python language), Origin (graphical analysis software), and Matlab (numerical computing environment). The developed spreadsheet demonstrated excellent adjustment capabilities, confirmed by the same values of the coefficients of determination (R2) calculated in each software. Thus, ADSORB-XL emerged as the most affordable option, providing fast results with minimal computational knowledge. Notably, the research highlights how the unique attributes of each software, including processing speed, user interface design, and analytical depth, influence its suitability for different research scenarios. These results define key criteria for selecting analytical tools that balance power and accessibility. Validation on conventional platforms shows correctly applied nonlinear regression yields reliable results across experimental conditions, enhancing methodological standards.

Abstract in English:

Furanocadinan-type sesquiterpene itapejarafuran has been reported as part of the essential oil of Baccharis punctulata DC. (Asteraceae) leaves. This species is widely distributed in South America and popularly known as “chilka saru saru” in Bolivia and traditionally used for treatment of luxations, contusions and asthma. Since the stereochemistry of molecules can drastically modify its biological activity, in this study we aimed to isolate and determine the complete stereochemistry of the compound. The structure of itapejarafuran and its absolute configuration were determined by nuclear magnetic resonance, optical rotation and electronic circular dichroism with high-level quantum-chemical calculations. The corresponding computational calculations indicated that this compound obtained from the essential oil of Baccharis punctulata leaves corresponds to the RSR isomer, (5R,5aS,9aR)-4,5,5a,6,7,9a-hexahydro-1,5,8-trimethylnaphtho[2,1-b]furan. This is, to the best of our knowledge, the first determination of the absolute configuration of itapejarafuran from B. punctulata. Establishing the stereochemistry for this furanosesquiterpene provides a robust framework for future structure-activity studies and chemotaxonomic comparisons within Baccharis genera, in which furanocadinane skeletons are frequent components of essential oils. Furthermore, itapejarafuran exhibited toxicity against cancer on MIA PaCa-2 cells (half-maximal inhibitory concentration (IC50): 150 µM), indicating a potential application as chemotherapeutic candidate and providing insights for future investigations.

Abstract in English:

“Saborosa” (Selenicereus setaceus) is a fruit native to the Brazilian Cerrado that remains poorly studied regarding its volatile organic compound (VOC) profile. This study aimed to optimize VOC extraction from the pulp using headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME/GC-MS) and three semipolar fibers (polydimethylsiloxane/divinylbenzene (PDMS/DVB), carboxen (CAR)/PDMS/DVB, and CAR/PDMS) under different extraction times and temperatures. A total of 24 compounds were identified, including organic acids, ketones, alcohols, esters, hydrocarbons, monoterpenes, and sesquiterpenes, with 20 compounds reported for the first time in this species. Extraction time significantly influenced the performance of the CAR/PDMS/DVB fiber, whereas temperature affected PDMS/DVB, resulting in higher compound recovery. The CAR/PDMS fiber showed no significant dependence on these variables. Optimal extraction conditions were 35 °C and 60 min, yielding the highest number of analytes. The identified VOCs contribute to key sensory and identity descriptors of the fruit. Compounds such as hexanal, 1-hexanol, 3-methylbutan-1-ol, and (E)-2-octenal were associated with fruity and citrus-green notes. These results expand the chemical knowledge of this still underexplored species and may be associated with fruit quality markers. To date, this is the most comprehensive and optimized study on VOC extraction and characterization from S. setaceus pulp.

Abstract in English:

“Cagaita” is the fruit of the “cagaiteira” (Eugenia dysenterica), a native fruit tree of the Myrtaceae family, found in the Brazilian “Cerrado”. This fruit is a rich source in nutrients and bioactive compounds and it presents high potential for marketing products, such as jellies, ice cream, and beverages. The objective of this work was to evaluate the chemical profile of chemical compounds in the pulp, peel, and seed of E. dysenterica. The chemical profile of the fixed compounds in the “cagaita” was evaluated, using the paper-spray ionization method coupled with mass spectrometry (PS-MS) in positive and negative ionization modes. In the positive mode, forty different compounds might be proposed as chemical constituents, nine of which are from different chemical classes including flavonoids, sugars, coumarins, fatty acids, and tannins, three of which are exclusive to the peel and two to the seed. In the negative mode, 31 compounds were identified, including organic acids, flavonoids, tannins, sugars, phenylpropanoids, hydroxybenzoic acids, and fatty acids. The PS-MS analysis has once again proven itself to be a simple, fast, and efficient technique in obtaining the fingerprints of the constituents of the “cagaita” enabling easily the identification of several compounds.

Abstract in English:

The distribution and mobility of potentially toxic elements were evaluated in 50 topsoils from the Caatinga biome in Brazil using BCR (Community Bureau of Reference) sequential extraction, the risk assessment code (RAC), and principal component analysis (PCA). The residual fraction was dominant for most elements, with concentrations reaching up to 154 mg kg-1 for Ni and 82 mg kg-1 for Cr. However, significant mobility was observed in the acid-soluble fraction, particularly for Ni (0.16-10 mg kg-1) and Cd (0.12-1.24 mg kg-1), whereas Pb (0.75-15 mg kg-1) and Zn (0.34-4.6 mg kg-1) showed moderate mobility. Consequently, RAC classified Ni (13.3%) and Cd (12.7%) as medium environmental risk, while other metals showed low risk. PCA revealed that soil pH correlated positively with Ni, Cu, and Cr, and negatively with Zn, Cd, and Pb. Organic matter and soil texture were also important in influencing metal mobility. These findings indicate that, despite the geogenic origin of these soils, the high mobility of Cd and Ni in specific pH conditions poses potential ecological risks. This suggests that environmental monitoring in the semi-arid Caatinga ecosystem should focus on bioavailable fractions rather than total content to prevent trophic transfer effectively.

Abstract in English:

Biodiesel can be obtained from the transesterification reaction of triglycerides with short-chain alcohols in the presence of a catalyst. Some of the methyl esters present in biodiesel are unsaturated, which favors the oxidation process and can be slowed or suppressed with the addition of antioxidants. There are many options and varieties of synthetic antioxidants, such as tert butylhydroquinone (TBHQ) and butylhydroxytoluene (BHT). However, plant extracts, containing substances such as anthocyanins and flavonoids, with antioxidant properties can be used because they are effective in protecting biodiesel from oxidation. In this study, we evaluated the antioxidant behavior of jambolan pulp extract (Syzygium cumini Lamarck) in biodiesel, in the presence and absence of Cu2+, at different exposure times at a temperature of 110 °C with a flow rate of 10.00 L h-1 of air using proton nuclear magnetic resonance (1H NMR) spectroscopy. The high-intensity signals obtained by 1H NMR spectroscopy showed that the biodiesel used was composed of 98.14% esters, with 35.35% saturated and 62.79% unsaturated esters. The low-intensity resonance signals showed that the main thermal degradation products were epoxides, aldehydes and hydroperoxides. The jambolan pulp extract reduced the oxidation reaction rate of biodiesel even in the presence of Cu2+ ions, demonstrating its potential use as an antioxidant.

Abstract in English:

This study presents an in-depth characterization of biochars produced by slow pyrolysis of LignoForce™ softwood (SKL) and hardwood (HKL) kraft lignins, aiming to development biomaterials for industrial and/or environmental applications. The as-received lignins were pyrolyzed under static air atmosphere in the range of 300 to 500 °C. Kraft lignin biochars were characterized by scanning electron microscope (SEM), elemental analysis, Raman spectroscopy, bomb calorimetry (for higher heating values (HHV)), and calcination. SEM micrographs showed that biochars presented important structural changes caused by the heat treatment in relation to the original samples. Biochar became more compact and friable as the pyrolysis temperature increased. In Raman spectroscopy, bands attributed to carbonaceous materials were identified, with ID/IG ratios decreasing with increasing temperature, indicating a greater ordering of the carbonaceous structure. Based on elemental analysis, HHV were estimated at 26 and 31 MJ kg–1 for HLK and SKL biochars, respectively, which were among the highest for this class of biomaterials. The CO2 adsorption capacity of the biochars increased with pyrolysis temperature, reaching 51.2 and 50.0 cm3 g–1 for HKL and SKL pyrolyzed at 500 °C, respectively. This study demonstrated that biochars with high HHVs and good CO2 adsorption capacities can be produced from kraft lignin without requiring any additional pretreatment, such as activation or doping.

Abstract in Portuguese:

HISTORICAL GEOCHEMICAL BASELINE OF INORGANIC CONTAMINANTS IN SEDIMENTS OF THE CANAVIEIRAS ESTUARY - BAHIA, BRAZIL. This study establishes a historical geochemical baseline for superficial sediments of the Canavieiras estuary, Bahia, Brazil, based on sampling conducted at 32 stations. The characterization involved the determination of trace elements (As, Ba, Co, Cr, Cu, Mn, Mo, Ni, Pb, Se, Sr, Ti, V and Zn) by ICP OES (inductively coupled plasma optical emission spectrometry) and Fe by XRF (X-ray fluorescence spectrometry), employing robust statistical treatment (Z-score normalization and Kruskal-Wallis/Dunn tests). The results evidenced a strong lithogenic control over the distribution of most elements, with significant correlations (R2 > 0.83 between Co, V, and Cr) reflecting the terrigenous heritage of the Barreiras Group. Ecological risk assessment, according to CONAMA Resolution 454/2012, revealed two distinct non-compliance scenarios: (i) arsenic (As) showed widespread concentrations above level 1 (8.40-31.90 mg kg–1), attributed to natural background and local redox conditions; and (ii) lead (Pb) (14.33-58.48 mg kg–1), despite an overall mean below the regulatory threshold, exhibited localized contamination above level 1 at eight stations, delineating hotspots of anthropogenic accumulation. It is concluded that, with the exception of natural As anomalies and critical zones of Pb enrichment, the estuarine system maintained geochemical integrity during the evaluated period, with these data serving as a fundamental historical reference for monitoring the region’s environmental evolution.

Abstract in English:

This study investigated the vibrational properties and adsorption geometries of the neonicotinoids imidacloprid (IMD) and thiamethoxam (THX) on silver nanoparticles (AgNP) through surface-enhanced Raman scattering (SERS) combined with density functional theory (DFT) calculations, providing critical insights into the chemical interactions between pesticides and metallic surfaces. Crucially, the vibrational assignment was meticulously performed using the potential energy distribution (PED) calculated based on DFT calculations, resulting in an exceptionally detailed molecular attribution. The Raman and SERS spectra of IMD and THX were analyzed, revealing preferentially enhanced bands associated with specific molecular groups in SERS. The SERS enhancement of normal modes involving the nitro and 1,3,5-oxadiazinan-4-ylidene groups for THX, as well as the nitro and 4,5-dihydroimidazole groups for IMD, demonstrated their preferential adsorption geometries on AgNP surfaces. DFT simulations helped to elucidate the molecular anchoring mechanisms, highlighting charge transfer effects between the pesticides and silver atoms. Furthermore, distinct IMD:THX mixtures confirmed the ability of SERS to distinguish between the two compounds, showcasing the applicability of the SERS technique in analyzing complex systems. The findings emphasize the potential of SERS spectroscopy as a rapid, cost-effective, and sensitive analytical tool for detecting neonicotinoid residues.

Abstract in English:

Premature birth accounts for nearly half of perinatal deaths worldwide, making its prevention a major public health priority. Although vaginal administration of natural progesterone is an effective prophylactic strategy, its daily use is often associated with irritation and low patient adherence. In this context, biodegradable, biocompatible, and mucoadhesive polymers such as chitosan and gelatin emerge as promising materials for controlled drug delivery systems. This study aimed to develop and characterize progesterone-loaded ovules based on chitosan and gelatin for the prevention of premature birth. The formulations were produced by lyophilization and evaluated in terms of morphology, chemical structure, thermal stability, swelling behavior, biodegradation, and cytotoxicity. Fourier transform infrared spectroscopy (FTIR) analysis indicated successful incorporation of progesterone into the polymeric matrix. Swelling and biodegradation assays provided insight into the degradation profile of the system, suggesting that the matrix may support modulated progesterone diffusion. Thermal analysis (TGA) showed that pure chitosan presented greater thermal stability, while the addition of gelatin and progesterone slightly reduced this property. Cytotoxicity results confirmed the biocompatibility of the developed formulations. Overall, the findings suggest that these ovules are a promising platform for progesterone delivery and may contribute to innovative biomaterial-based approaches for the prevention of preterm birth.

Abstract in Portuguese:

The aim of this study is to compare technological methods for the incorporation of thyme essential oil into a sodium montmorillonite clay and in an organophilic clay in order to produce a clay with potential application in food packaging. Two methods of thyme essential oil incorporation into the selected clays were compared, one method based on the evaporation-adsorption mechanism; and the other method based on the emulsion mechanism, applying mechanical agitation and sonication, and the use of Tween 80. The samples were characterized via thermogravimetric analysis, Fourier transform infrared spectroscopy and X-ray diffraction. Both methods showed results that confirmed the incorporation of thyme essential oil. Due to the interaction of Tween 80 with thyme essential oil and clays, the emulsion method did not provide reliable results for the quantitative determination of thyme essential oil. The evaporation-adsorption method promoted the incorporation of thyme essential oil onto the external surface of the clay. Among the hybrids obtained by this method, the organophilic clay-based hybrid was the most effective, showing an incorporation of approximately 17 wt.%, along with water.

Abstract in English:

This study involved the synthesis of a novel adsorbent by grafting chitosan with acrylic acid and methyl methacrylate, followed by crosslinking with N,N’-methylenebis(acrylamide). The adsorption process exhibited pseudo-second order kinetics for both metals and reached equilibrium within 1300 min. The Langmuir isotherm revealed a maximum adsorption capacity of 94.01 ± 7.344 mg g-1 for HgII and 159.4 ± 24.43 mg g-1 for CdII. The Freundlich isotherm indicated favorable non-copper adsorption for both metals. The Dubinin-Radushkevich isotherm indicates an adsorption mechanism involving ion exchange. The presence of K+, Na+, Mg2+, and Ca2+ ions at a concentration of 0.5% and a pH of 2.0 resulted in a decrease in adsorption capacity. The reuse of the adsorbent was investigated, and the material did not lose its removal efficiency after three cycles. This study indicates that the sample can be used to remove CdII and HgII from aqueous solutions, but it does not demonstrate self-disinfecting properties.

Abstract in English:

Herein, we report the synthesis of structured triacylglycerols (TAGs) enriched with oleic acid through the enzymatic interesterification of palm stearin and unsaturated fatty acids derived from rainbow trout viscera oil. Both materials are industrial by-products with significant biotechnological potential. The research aimed to determine the percentage of oleic acid insertion of the unsaturated fatty acids (UFAs) at the sn-1 and sn-3 positions of the triacylglycerols present in palm stearin. A central composite experimental design was used with regioselective sn-1,3 enzyme, specifically Lipozyme TL IM. The effects of three variables were examined: time (8 to 30 h), the molar ratio of stearin to fatty acids (1:3.66), and temperature (45 to 80 °C). The resulting products were analyzed using high-performance liquid chromatography, achieving oleic acid insertion percentages of up to 68.32 ± 0.0114% under the optimal conditions. Additionally, a quality analysis of the starting oils and reaction products was performed. This analysis revealed changes in parameters such as the saponification index, peroxide levels, iodine values, and unsaponifiable matter, confirming the formation of new compounds. These findings highlight the potential of utilizing industrial byproducts, such as palm stearin and trout viscera oil, as starting materials for the synthesis of fatty acid-structured lipids through enzymatic interesterification.

Abstract in English:

Aspiration pneumonia is one of the leading causes of death among older adults with dementia, and to address this health problem, cannabidiol (CBD) stands out due to its neuroprotective properties. The aim of this study was to develop and characterize gelatin/carboxymethylchitosan membranes with cannabidiol as a potential sublingual delivery system for cannabidiol in neurological disorders associated with bronchoaspiration. The methodology involved the preparation of membranes with different gelatin/carboxymethylchitosan (CMQ) ratios (90:10, 80:20, and 70:30), using Tween 80 to ensure CBD dispersion. The membranes were characterized by optical microscopy (OM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), solubility, swelling, and cytotoxicity. OM showed that increasing the CMQ fraction resulted in greater structural heterogeneity. pH values remained within the physiological range (7.1-7.4). FTIR suggests possible interactions among the components, indicating drug incorporation. Swelling and solubility assays demonstrated that the presence of CMQ and CBD reduced water uptake and mass loss in different simulated media. TGA indicated that CBD exerted a plasticizing effect. Cytotoxicity assays showed cell viability above 80%, confirming the biocompatibility of the system. These results reinforce the potential of the membranes as a sublingual delivery system for cannabidiol and as an auxiliary strategy for the prevention of bronchoaspiration.

Abstract in English:

This work presents a loading-dependent free-volume geometric framework for CO2 adsorption in NaX zeolite (FAU-type) based on the structural function interpreted as free pore volume within α-cavity. Unlike classical approaches, it is loading-dependent, enabling a continuous and purely analytical description of the geometric evolution of the molecular packing trajectory. Structural descriptors are derived considering the initial free pore volume and the average free volume consumed along the path and ψ is the cumulative molecular packing fraction. For two representative extreme conditions, ηVmax = 3.57 mmol g-1 (348 K, 1 bar) and ηVmax = 7.26 mmol g-1 (298 K, 10 bar), these descriptors show marked differences: low-loading condition leads to reduced initial free-pore volume (~ 157 Å3 molecule-1), and ψ = 0.64 mmol g-1, indicating weak molecular rearrangement within the adsorption pore. In contrast, the high-loading condition preserves higher F0 and ψ values, reflecting a larger structural rearrangement of the confined adsorbed phase. These descriptors provide a robust measure of the geometric severity of molecular reorganization required to NaX-CO2 reaches the saturation inside the confined α-cavity. This framework can be interpreted as a loading-dependent extension, adapted to confined adsorption systems, of the classical free-volume theory, establishing a bridge between macroscopic adsorption data and nanoscale structural interpretation.

Abstract in English:

Based on circular economy principles, sustainable biochar materials were produced from residues generated during the consumption of Brazilian-pine seeds (Araucaria angustifolia). Pristine and ZnCl2 modified biochar were prepared via thermochemical conversion and characterized. The applicability of these materials was evaluated using Cr species at low concentrations, targeting their use in analytical strategies, as green extraction and preconcentration. Batch adsorption experiments evaluated the influence of pH, contact time, and concentration. Adsorption efficiencies above 75% were achieved using a biochar dosage of 3 g L-1 and an equilibrium time of 3 h. The pristine biochar showed adsorption of CrIII at pH 4-5, whereas the modified biochar exhibited enhanced affinity toward CrVI with the pH range of 4-8. The adsorption behavior was influenced by chromium speciation and the characteristics of the biochar. Adsorption kinetics analyses indicated that chromium-biochar interactions involved both chemisorption and physisorption mechanisms. The equilibrium data were adequately described by Langmuir and Freundlich models. The maximum adsorption capacities reached 0.87 mg g-1 for CrIII on pristine biochar and 1.9 mg g-1 for CrVI on modified biochar. Overall, the results highlight the potential of these biochars as green solid-phase materials for chromium speciation, with promising applications in analytical preconcentration.

Abstract in English:

Fertilizer pellets were prepared, derived from mixtures of biochar (obtained from pruning waste) and NPK (derived from a mixture of urea, phosphate rock and potassium chloride) in different proportions. The mixtures were characterized by Brunauer-Emmet-Teller (BET) method, pH, electrical conductivity, water absorption, near-infrared (NIR) spectroscopy and X-ray fluorescence (XRF). A completely randomized experimental design using one-way analysis of variance (ANOVA) was performed to determine the effect of biochar on NO3- (N), NH4+ (N), PO43- (P) and K+ (K) leaching using soil columns and Dunnett and Tukey’s methods were used to identify variations between treatments. The results showed that the higher biochar content in the fertilizer pellet resulted in the lower leaching of NH4+ (N), PO43- (P) and K+ (K), due to the improvement in surface area and the high calcium content found in biochar. The addition of biochar does not have a significant effect on the leaching of NO3- (N). Whitin the mixtures studied of NPK:biochar, the formulation with 1:2 ratio is the one that presents the lowest leaching of nutrients. In addition, this fertilizer pellet has a basic pH, low electrical conductivity and high-water absorption capacity, making it a good alternative for the use in agricultural production.

Abstract in English:

Water/seawater electrolysis is considered a pivotal technological route toward scalable and eco-friendly hydrogen generation and is recognized as a promising renewable alternative to conventional fossil fuels. Herein, high-entropy NiFeCoCuW layered double hydroxide (LDH) flower-like microspheres are fabricated via a facile one-pot hydrothermal strategy as efficient and stable oxygen evolution catalyst. An overpotential of only 118 mV is required for the as-prepared NiFeCoCuW-LDH catalyst to achieve a current density of 10 mA cm-2 in alkaline water, highlighting its exceptional oxygen evolution reaction (OER) performance. In alkaline seawater (1 M KOH + seawater), the catalyst achieves an OER overpotential of 122 mV at 10 mA cm-2, while retaining satisfactory electrocatalytic activity. The NiFeCoCuW-LDH catalyst fabricated in this work not only possesses the superior catalytic activity and low cost of transition metal-based catalysts, but also exhibits the flexible electronic regulation capability and multimetal synergistic effects of high-entropy materials, which endows the catalyst with exceptional electrocatalytic performance.

Abstract in English:

This study quantified Cd, Cu, Fe, Mn, and Zn in ten commercial cow’s and buffalo milk cheese using flame atomic absorption spectrometry (FAAS) after microwave-assisted digestion with nitric acid and hydrogen peroxide. The analytical procedure was designed under the principles of green chemistry, employing reduced volumes of reagents, efficient microwave-assisted digestion, and minimal waste generation. Method accuracy was confirmed by recovery tests (80.1-120.0%), with limits of detection and quantification ranging from 0.2-3.0 and 0.6-9.0 mg kg-1, respectively. In cow’s milk cheese, Cd (0.55 0.67 mg kg-1), Cu (6.92 7.53 mg kg-1), Mn (0.74 mg kg-1), and Zn (12.71-66.63 mg kg-1) were detected, while buffalo cheeses contained Cd (0.34 0.37 mg kg-1), Cu (2.75 mg kg-1), and Zn (8.14-49.33 mg kg-1). Iron was below limit of detections in all samples. Notably, Cd concentrations in three cow’s milk cheese exceeded ANVISA’s (Brazilian Health Regulatory Agency) maximum permissible levels. However, risk assessment indicated that estimated daily intakes (EDI) for all metals were below provisional maximum tolerable daily intake (PMTDI), and hazard quotients (HQ) were < 1, indicating the absence of non-carcinogenic risks. These findings highlight the importance of monitoring Cd contamination in dairy products, while also demonstrating that environmentally friendly analytical strategies can ensure reliable results with reduced ecological impact.

Abstract in Portuguese:

Fusaric acid is a mycotoxin produced by fungi of the genus Fusarium, first described in 1934. Research has demonstrated a correlation between this mycotoxin and the virulence of Fusarium fungi in plants, causing significant economic losses in crops such as pineapple, watermelon, cucumber, banana, and others. These fungi are highly adaptable and ubiquitous in soil; however, the understanding of their mechanism of toxicity in plants is still limited. This review focuses on research involving fusaric acid and its derivatives, covering the biological activities reported since 2000. The analysis encompassed 69 experiments, which revealed 11 distinct types of biological activities. The main activity reported was antimicrobial, comprising 39 different species of microorganisms against which fusaric acid exhibited some effect. The derivatives and analogs reported during this period, comprising a total of 100 compounds, were also discussed. These were categorized into natural, semi-synthetic, and synthetic. Based on the experiments performed, the forms obtained, and the main activities analyzed, topics such as biotransformation, detoxification, and phytotoxicity were addressed, among others. With this updated review, we aim to present novel perspectives on the discovery of new biological activities for fusaric acid and its derivatives.

Abstract in Portuguese:

Ureases are nickel-dependent enzymes widely distributed in nature that play fundamental roles in both healthcare and agriculture by catalyzing the hydrolysis of urea into ammonia and carbon dioxide. This enzymatic activity is of considerable scientific and technological relevance, as it represents a promising target for the development of novel products with applications across multiple fields. In healthcare, urease functions as a virulence factor in several pathogenic microorganisms. On the other hand, the ureolytic activity of ureases on soil leads to nitrogen loss through volatilization, which negatively impacts plant nutrition and agricultural productivity. This compilation provides an overview of urease in the scope of medicine, agriculture and biotechnology. The structure of the enzyme, mechanism of action of identified inhibitors, and prospects for the research and development of new urease-inhibiting compounds are also discussed. Advancing knowledge on the biological properties of urease is essential for developing innovative strategies with significant impacts on agricultural sustainability, human health and biotechnology.

Abstract in Portuguese:

Metal sulfide quantum dots (QDs) have gained remarkable attention in recent years owing to their broad optical tunability, high photochemical stability, and potential to replace toxic cadmium-based systems. These semiconductor nanocrystals exhibit sizeand compositiondependent electronic structures, enabling precise control of their absorption and emission across the visible and near-infrared regions. The transition from binary systems such as ZnS and CdS to more complex ternary and quaternary compositions, including CuInS2, AgInS2, and ZnCuInS/ZnS, has significantly expanded the versatility of these materials. Through compositional engineering and surface modification, it has become possible to optimize parameters such as photoluminescence quantum yield, defect density, and environmental compatibility. Consequently, metal sulfide QDs have emerged as promising candidates for diverse applications, including fluorescence bioimaging, photocatalytic degradation of organic pollutants, and solar energy conversion in next-generation photovoltaic devices. This review provides an integrated perspective on recent advances in the synthesis and compositional design of binary, ternary, and quaternary metal sulfide QDs, emphasizing the relationship between synthetic strategies, composition, and optical properties, particularly in green chemistry approaches. Key challenges are also highlighted, including control over growth mechanisms, surface chemistry, stability, and toxicity, which remain critical for their practical application in sustainable technologies.

Abstract in Portuguese:

This work is intended to survey a range of supervised pattern recognition methods. The main differences between class modelling and discriminant methodologies are presented. Their advantages and disadvantages are highlighted. Suggestions are given when to use one or another methodology. The discriminant methods MLR-DA (multiple linear regression-discriminant analysis) and PLS-DA (partial least squares-discriminant analysis) are discussed as well as the class modelling SIMCA (soft independent modeling of class analogy) and its variants Mod-SIMCA (modified-SIMCA), Alt-SIMCA (alternative-SIMCA) and DD-SIMCA (data driven-SIMCA). A real example to classify rice samples from China is presented.

Abstract in Portuguese:

Principal component analysis (PCA), independent component analysis (ICA), and common component analysis (CCA) were employed to assess the chemical composition of mineral waters from France and Brazil (specifically, the states of Paraná and São Paulo). The primary objective is to utilize a straightforward dataset and disseminate the CCA chemometric tool in the Portuguese language. Furthermore, this comparative approach is particularly pertinent for evaluating the extent to which CCA could add value to the arsenal of more commonly known and disseminated chemometric tools. These methods are exploratory and unsupervised multivariate analysis tools, each based on distinct optimization criteria and distinct goals: variance maximization, independence, and shared structure for PCA, ICA, and CCA, respectively. The results showed that CCA better discriminates between the samples of France and Brazil, with a Mahalanobis distance among score groups of 4.2000, followed by PCA with 3.8339, and ICA with 2.1797.

Abstract in Portuguese:

We present a discussion about the letters written by graduates from the years 2011, 2012, and 2014 to the graduates of 2023 and 2024. These letters were written, sealed, and stored in a cabinet by the professor, who also did not know their content, and were opened by the graduates in the not-too-distant present. The graduates also got in touch with their peers from the past to find out how they are doing and whether they have left the profession or not. The results show aspects that encompass political and social issues, difficulties in studying Chemistry, time to completion, professional choices, leisure, fun, and the monkeys of UFG (Universidade Federal de Goiás). The conversations between them, after reading the letters, revolved around whether or not to leave teaching, the difficulties of the career, and advice from the now teachers to the current graduates. The analysis of the letters and conversations shows that no effective changes occurred during this time interval and confirmed several problems already discussed in the literature that seem to have persisted, persist, and, unfortunately, will persist.

Abstract in Portuguese:

This classroom-oriented study goes beyond simple visualization by directly comparing laser diffractometry and light microscopy measurements to quantify micron-scale spacings in commercial CDs/DVDs (compact disc/digital versatile disc) and electron-microscopy grids. Diffraction angles from reflection (CD/DVD) and transmission (grids) patterns were captured using a digital camera. We systematically validate the diffractometry results with microscopy, teaching the scientific principle of cross-validation. Furthermore, by employing grids with square, rectangular, and hexagonal symmetries, we provide a tangible introduction to symmetry and reciprocal space, demonstrating the inverse relationship between grating spacing and diffraction pattern scale. Designed for educational settings, these experiments use affordable materials to teach core principles of diffraction with applications in material science and chemistry.

Abstract in English:

In an increasingly digital world, education has also seen a transition to the use of innovative technologies that promise to revolutionize the teaching and learning process. Augmented reality (AR), for example, has the potential to improve the educational environment by making abstract concepts more accessible to students. In the chemistry field, a subject often considered complex, the ability to visualize and interact with phenomena can be particularly valuable. However, few research involving the use of AR applications (apps) in chemistry teaching have approached their design and application based on cognitive theories. This research addressed this gap in the literature by analyzing seven AR applications for teaching chemistry available on Google Play in 2025. The results show how cognitive theory of multimedia learning (CTML) principles are implemented in AR applications while also offering relevant considerations for developers and educators. Data points to the need to produce educational applications that include pedagogical aspects, which will allow the use of AR to be effective and inclusive. Finally, CTML has proven to be a relevant approach for developing and applying AR apps, providing important theoretical guidelines for developers and instructional designers to create applications based on learning theories.

Abstract in Portuguese:

This study aimed to examine the potential of a role-playing game (RPG) as a pedagogical intervention to promote the learning of Molecular Geometry concepts, grounded in Jean Piaget’s theory of equilibration. This theoretical framework offers a constructivist, genetic, and epistemological perspective on how cognitive structures are reorganized during the learning process. To this end, we conducted a qualitative case study in which an RPG was designed and implemented with pre-service Chemistry teachers enrolled in a teacher education program at the Federal University of Piauí, in northeastern Brazil. The intervention sought to engage students in exploring key concepts such as molecular shape and geometry through collaborative and immersive gameplay. Data were collected using audio and video recordings, complemented by field diary notes, and subsequently transcribed and imported into MaxQDA® for analysis. Applying content analysis, we identified the emergent analytical category of “understanding”. The results indicate that the RPG functioned as a meaningful learning tool, supporting conceptual understanding of Molecular Geometry and highlighting its potential to enrich instructional practices in Chemistry teacher education.

Abstract in Portuguese:

PROBLEM SOLVING BY UNDERGRADUATE CHEMISTRY STUDENTS: ACRYLAMIDE IN FOOD AS A THEME. This paper aims to report and analyze a teaching activity carried out in higher education with the purpose of fostering problem-solving (PS) skills in chemistry students. Three problems about acrylamide in food, in the form of interrupted case studies, were solved by students divided into twelve groups. Answers developed during the problem investigation process were analyzed considering the problem-solving skill indicators shown in the IDEAL Problem-Solving Model. The results showed the development of the groups in each of the stages outlined in the Model and the completion of the five stages for PS outlined therein by all groups, demonstrating the potential of the activity under analysis to achieve the initially outlined objective.

Abstract in English:

Thermodynamics is a crucial component of the inorganic chemistry curriculum in local normal universities. Currently, the teaching of this subject faces several practical issues, including ambiguous content positioning, poor connection between high school and college education, significant cognitive barriers for students, and insufficient class hours. This paper proposes a comprehensive reform approach centered on “content reconstruction - method innovation - technology empowerment”. It simplifies theoretical teaching through the “borrowing” approach, strengthens the logical connection between thermodynamics and the four major equilibria as well as the properties of elements, builds a knowledge map and an artificial intelligence (AI)-assisted hybrid teaching model, and integrates elements of ideological and political education into the curriculum. Practical results show that this approach effectively enhances students’ ability to integrate knowledge and their scientific literacy, significantly improves teaching quality, and provides a reference for teaching optimization in similar universities.

Abstract in Portuguese:

In this study, we sought to investigate how and in what ways a proposal based on Bauman’s perspective and the theoretical contribution of Critical Environmental Education (CEE) can influence the environmental training process of chemistry teachers. The proposal was developed within the scope of an Environmental Chemistry course and involved the participation of 17 students in initial training. During the classes, existential and political issues affecting society and the environment in times of liquid modernity were discussed, integrating, to a certain extent, chemical concepts and processes into the analysis of real situations. A questionnaire and an activity comprised the data for this study, which were submitted to discursive textual analysis. Among the influences of the approach, we highlight the potential to sensitize and involve students in debates about the environmental agenda. The proposal provided guidelines, that is, elements for students to recognize problematic situations that affect not only the environment but also individuals and the community in different ways. The approach contributed to critical environmental education, such as indignation and insight into political and economic injunctions in the current socio-environmental context, also revealing the multifaceted nature of the environmental dimension.

Abstract in English:

This report describes how 25 second-year undergraduate chemistry students perceived and were impacted by an active learning strategy introduced in the Organic Compounds Analysis course at the São Carlos Institute of Chemistry, University of São Paulo. The intervention centered on a class activity where students developed structured protocols for interpreting organic spectroscopic data. The activity integrated principles from Computational Thinking and Writing-to-Learn, encouraging students to decompose complex problems, recognize data patterns, and articulate reasoning in written form. To evaluate the impact of this intervention, a descriptive educational study was conducted using post-activity questionnaires to collect quantitative data on students’ motivation, confidence, and perceptions of the protocols’ usefulness. Results showed that 15 out of 25 students felt more motivated to study in advance, and 13 reported increased confidence during exams when using the protocols. Additionally, 23 students indicated that preparing the protocols deepened their understanding of organic spectroscopy concepts and improved exam performance. Although some students reported difficulties synthesizing information from multiple spectroscopic techniques, the overall reception was positive. The findings suggest this activity not only enhanced learning efficacy in organic spectroscopy but also helped students develop greater confidence during assessments.

Abstract in Portuguese:

Chemometrics has gained significant importance in higher education and the job market, leading to an increasing number of teaching approaches for various chemometric tools. In this context, the present work aims to contribute to the development and expansion of educational strategies by presenting an experimental proposal for teaching multivariate curve resolution using alternating least squares (MCR-ALS). This proposal is designed for implementation in higher education courses that include chemometric topics in their curricula. Based on ultraviolet and visible (UV Vis) spectrophotometric data collected from a binary solution of colorants, the activity covers essential concepts of chemometrics and MCR-ALS, through a free online platform that performs chemometrics without programming. Furthermore, a pseudo-univariate calibration is also considered. The objective is to promote a deeper understanding of MCR-ALS among students, encouraging both conceptual comprehension and practical application of this chemometric tool and its associated applications. Furthermore, this experimental proposal is intended to support the development of innovative teaching practices in chemometrics within higher education settings.

Abstract in Portuguese:

Understanding the importance of education for ethnic-racial relations, especially after 20 years of Brazilian Law 10.639/03, which requires the inclusion of African and Afro-Brazilian history and culture in the school curriculum, it is imperative to develop work on the subject in different areas of teaching, also reflecting on teacher training. In view of the above, this work aims to characterize a proposal for teaching and training chemistry teachers to address racism, in conjunction with the Black Movement and in dialogue with the educational perspective of Paulo Freire and Abdias Nascimento on racism. To this end, the Chemistry Education and Social Inclusion extension program developed at the Federal University of Santa Catarina is presented, which contributes to the teaching and training of chemistry teachers in addressing the problem of racism, a process that is permeated by actions of resistance.

Abstract in Portuguese:

This work uses the electro-oxidation of alcohols, particularly ethanol, as a framework to discuss fundamental principles of electrochemistry and electrocatalysis, emphasizing their relevance to the energy transition and to the development of cleaner and more efficient power sources, such as fuel cells. From basic laboratory electrochemical systems to more advanced technological devices, the discussion underscores the central role of electrocatalytic surfaces at different levels of structural complexity, highlighting the ways in which surface structure and chemical composition govern catalytic performance. Overall, we show that the electro-oxidation of small organic molecules and their derived technologies hold significant promise for reducing dependence on fossil fuels. However, achieving full technological viability requires a deeper molecular-level understanding and the continued development of more efficient, selective, and durable electrocatalysts.

Abstract in Portuguese:

This article aims to report on the application of a teaching sequence (TS) based on the cooperative jigsaw method, which culminated in the individual production of popular science texts (PSTs) by undergraduate chemistry students, based on the reading and interpretation of an original research article (ORA) on tropospheric ozone. The PSTs were analyzed, and it was possible to conclude that, for the most part, they contemplated characteristics inherent to this textual genre. In fact, the students were able to identify the central theme of the ORA, contextualizing the problem investigated therein and highlighting essential elements of scientific activity. Furthermore, figures of speech, especially analogies and personifications, were widely used and, although infrequently, expert opinions were also mentioned. Visual and textual resources also stood out, especially graphics and drawings. Photographs, maps, and tables, although less common, adequately complemented the presentation of information. This work has relevant implications for chemistry teaching, highlighting the feasibility of working with this genre in higher education, in various curricular components, depending on the ORAs selected, which will boost textual productions aimed at a broad audience.

Abstract in Portuguese:

The drug ivacaftor, one of the components of the medication Trikafta®/Kaftrio® recently incorporated into the Brazilian Unified Health System (SUS) for the treatment of cystic fibrosis, served as a model for the creation of an innovative teaching platform at PUC-Rio. The project integrated theory and practice in the teaching of organic chemistry, encouraging student autonomy and the development of critical laboratory skills within the academic schedule. The pedagogical strategy was based on the synthesis of two fundamental intermediates: ethyl 4-oxo-1,4-dihydroquinoline-3-carboxylate and 5-amino-2,4-di-tert-butylphenyl ethyl carbonate. Although the original synthetic routes described in patents served as a basis, modifications were implemented to optimize the process in a teaching environment. The final step consisted of forming the amide bond to connect the key intermediates, followed by basic hydrolysis. In the end, the synthesis of ivacaftor had an overall average yield of 40%.

Abstract in Portuguese:

This research investigated how Graduate Programs in Chemistry in Brazil contribute to teacher education for higher education teaching, with a focus on the knowledge required for academic teaching practice. The research stemmed from the observation that pedagogical training is still largely neglected in most programs, which tend to prioritize a logic centered on scientific excellence and productivity. A qualitative approach was adopted, using the application of questionnaires to faculty and graduate students as sources. Both faculty and students report imbalances between training for research and training for teaching, as well as institutional contradictions regarding the true goals of graduate education. It concludes that there is an urgent need to intentionally and structurally integrate the pedagogical dimension into the training provided by Chemistry graduate programs, in order to prepare critical, reflective educators committed to the transformation of higher education.

Abstract in English:

The thermodynamic equilibrium constant K is necessarily dimensionless, yet it is frequently treated as if it carried units. This paper traces the origin of the equilibrium constant and then derives the modern definition of K from the Gibbs free energy, emphasizing that K is dimensionless because it is the equilibrium value of the reaction quotient expressed in activities. Making the standard-state reference explicit shows why pure solids and pure liquids do not appear in equilibrium expressions and why the solvent term can be omitted in dilute solutions. The analysis also distinguishes the dimensionless practical constants from the unit-dependent variants and provides an explicit nondimensionalization linking them. As an application, the autoprotolysis of water is examined to show that pKa (H2O) ≈ 14.0 on the usual aqueous scale; the commonly quoted 15.7 is traced to mixing solvent and solute reference conventions. The same considerations clarify the concentration shorthand used for pH.

Abstract in English:

This manuscript reports the development and investigation of a mini-project activity focusing on teaching adsorption using biochar synthesized from ora-pro-nobis biomass during a five-week agro-industrial engineering course. For this purpose, the students synthesized biochar and performed batch adsorption experiments to remove methylene blue dye from aqueous solutions and interpreted the results of characterization tests. During the proposed activity, the students improved their skills in handling laboratory glassware, learned material characterization techniques, and understood mass ratios for batch adsorption experiments. Results demonstrated that, despite the adsorbent being produced using simple technique for teaching purposes, it showed innovative reflections. In addition, comparative analysis revealed that the efficiency of the adsorbent prepared from ora-pro-nobis showed similar results to other reported studies employing biochar. Findings from the present study suggested that biochar synthesis, adsorption experiments and characterization analyses effectively improve the understanding of undergraduate students about adsorption technology using locally available adsorbent materials.

Abstract in Portuguese:

Fluorescence spectroscopy, a technique for characterizing analyte emission, is widely used in industry and academia. However, its accuracy and potential are limited by the lack of teaching materials and training that demonstrate equipment operation and the impact of instrumental parameters. In this study, aiming to help fill this gap, particularly regarding experimental parameters that influence spectrofluorometric analyses, we developed a demonstrative experimental class on the principles of fluorescence spectroscopy, analyzing rhodamine-6G and pyrene solutions while varying emission and excitation slits and step (resolution). Students used data processing software to analyze and compare spectra, evaluating how molecules with different structures respond to these parameters. The results indicated improved conceptual understanding when students observed and rationalized chemical phenomena, reflected in an average score of 8 in experimental reports. The effectiveness of the teaching proposal was linked to integrating digital technology with demonstrative practice, making the class more engaging and encouraging reflection. This was supported by responses to questions 2 and 4 of the questionnaire, related to the contribution of the experiment to personal development and undergraduate chemistry learning, in which more than 90% of responses were classified as Good or Outstanding.

Abstract in Portuguese:

Analyzing the argumentative writing skills of university students is not a trivial task, as several elements need to be considered. This paper analyzed the quality of argumentative texts written by 53 undergraduate chemistry students on the mitigation of acrylamide in food, more specifically in French fries, coffee, and toast. The arguments, developed with the purpose of solving interrupted case studies (ICS), entitled Hot Potato, Espresso Acryla-Macchiato, and Wholewheat Promotion, were analyzed from the perspective of identifying their cogency, based on criteria of acceptability, relevance, and sufficiency. While the Hot Potato case focused on relatively straightforward processing interventions, the Espresso Acryla-Macchiato case required a greater integration of biochemical and technological aspects, and the Wholewheat Promotion case demanded the simultaneous consideration of chemical, technological, and sensory factors. This progression in complexity was likely reflected in the difficulties students encountered in integrating multiple aspects into a compelling argument, especially in the last ICS. Most students used reliable sources, such as graphs and tables, to support their premises, and more than half of them succeeded in constructing cogent arguments, which highlights the ICSs as a way to help students craft written arguments.

Abstract in Portuguese:

This study investigates the potentialities and challenges of a reflective process aimed at teacher training in higher education, developed within the postgraduate class Docência em Química no Ensino Superior. The study focuses on the process of collective reflections conducted by postgraduate students, supported by the reflective framework of Smyth and video-stimulated recall. A qualitative approach was adopted, involving audiovisual recordings of classes and collective discussions, which were analyzed through Content Analysis. The results suggest that individual reflection, supported by video, enhances the analysis of teaching practice, although with limitations. Collective reflection, in turn, indicates to expand this process by promoting dialogue, reducing teacher isolation, and fostering the (re)construction of pedagogical strategies and conceptual understandings. However, the findings also indicate challenges related to the operationalization of reflective processes and their adaptation to the context of higher education. The study highlights the potential of structured reflective practices in postgraduate contexts while emphasizing the need for further investigations and institutional support.

Abstract in Portuguese:

Tandem mass spectrometry (MS/MS) occupies a central position in experimental and analytical sciences, with collision-induced dissociation (CID) standing out as a fundamental technique for investigating molecular structures. In this process, molecular ions collide with a neutral gas, generating fragments that enable the elucidation of dissociation mechanisms. However, achieving a rational understanding of the collision phenomenon and its physicochemical implications - particularly the fragmentation channels and mechanisms - remains a theoretical challenge, especially when comparing models with experimental data obtained as a function of collision energy, as in energy-resolved mass spectrometry (ERMS). In this context, theories such as the transition state theory (TST) and the Rice Ramsperger-Kassel-Marcus (RRKM) model have become well established for providing robust descriptions of the physicochemical processes involved in CID. The foundation of their success lies in the application of quantum mechanics, particularly computational quantum chemistry. This integration makes it possible to predict spectra, estimate energy-dependent intensities, and, above all, model dissociation channels and mechanisms and determine reaction rate constants. Thus, this work presents a synthesis of the contributions of quantum chemistry to the theory applied to CID, highlighting its essential role in advancing understanding and consolidating theoretical foundations for mass spectrometry.

Abstract in Portuguese:

Twenty frequently asked questions in analytical chemistry are presented in a clear, instructive, and accessible manner. In the context of classical analysis, the text addresses questions related to types of solutions and their preparation, as well as key definitions of qualitative and quantitative methods, volumetric analysis, and heavy metals. It also covers essential topics such as analytical sequence, use of certified reference materials, distinctions among analytical methods, procedures, and techniques, and the main analytical figures of merit. Finally, fundamental aspects of instrumental analysis - including noise, background signals, detectability, detection and quantification limits, and calibration - are discussed, along with statistical considerations related to precision, linear modeling, and significance testing.

Abstract in English:

This article takes an educational perspective on a central limitation in biomass electrochemistry: the impossibility of driving multielectron reactions at the global thermodynamic potential. Standard electrode potentials are defined solely by the free-energy difference between global reactants and products (including electrons), whereas experimental operation depends on the stability of adsorbed intermediates formed along the reaction pathway. When free energy must be distributed across many elementary steps, large overpotentials usually arise as an inevitable thermodynamic consequence of multielectron reactions, even before kinetic effects are considered. To make this point clear, a graphical rather than mathematical approach is used to illustrate the thermodynamic origin of overpotentials, first revisiting simple twoand four-electron reactions such as the H+/H2 and O2/H2O couples. These examples highlight how adsorption energies determine the potential-determining step and why even apparently simple and well-understood processes require overpotentials. This framework is then extended to the interconversion of organic functional groups, specifically the alcohol/carbonyl and aldehyde/acid transformations, which represent key steps in the electro-oxidation of biomass-derived molecules.