TEDE Communidade:

Síntese e caracterização de compostos de coordenação mistos de lantanídeos para emprego como marcadores de munições e avaliação dos seus parâmetros termométricos

2026-08-03T12:51:29Z

Título: Síntese e caracterização de compostos de coordenação mistos de lantanídeos para emprego como marcadores de munições e avaliação dos seus parâmetros termométricos Autor: Silva, Júlia Pereira de Oliveira Primeiro orientador: Marques, Lippy Faria Abstract: In this work, we report the synthesis and structural characterization of new mixed-lanthanide compounds. Two main classes were investigated: mixed-lanthanide metal-organic frameworks (m-LnMOFs), with potential application as first-generation luminescent ammunition taggants when incorporated into gunpowder, and discrete mixed-lanthanide complexes, with potential application as second-generation taggants and in the field of luminescent thermometry. A new series of m-LnMOFs with the general formula [EuxGdyTb1-x-y(Hbtec)]n was synthesized and characterized in the solid state using various analytical and spectroscopic techniques, including a photophysical study. Due to their high thermal stability and tunable emissions, these materials were applied as selective ammunition taggants for .380 ACP (orange taggant), 9 mm Luger (red taggant), .40 S&W (yellow taggant), and 5.56 mm NATO (green taggant) calibers, allowing for the unequivocal distinction of different calibers based on their specific light emissions. Additionally, we propose incorporating the luminescent complex [Eu1.8Tb0.2(keto)6(bpy)2] into hollow-point projectiles for the .40 S&W caliber. Upon projectile deformation, the taggant is gradually released, enabling the visualization of the ballistic trajectory and tissue damage under UV light. Tests using ballistic gelatin and pork legs demonstrated the method's efficacy, showing great potential to assist forensic analyses, particularly during autopsies. Furthermore, three mixed discrete complexes were synthesized and characterized. Their emission spectra showed that the transições 5D4 → 7F5 (Tb3+) and 5D0 → 7F0 (Eu3+) transitions are temperature-dependent. Thus, the ratio between these intensities was employed as the thermometric parameter, characterizing a dual-emission ratiometric luminescent thermometer. These systems exhibited maximum relative sensitivities of 1.51 %K-1 at 343 K for [Eu0.4Tb1.6(keto)6(bpy)2], 2.38% K-1 at 353 K for [Eu0.6Tb1.4(keto)6(4,4’-dmbpy)2], and 5.48 %K-1 at 343 K for [Eu0.4Tb1.6(keto)6(4,4’-dmbpy)2], alongside high repeatability and low uncertainty, highlighting their potential as temperature sensors. The results demonstrated tunable luminescence emission in m-LnMOFs, as well as promising applications in forensics and thermometry for the discrete mixed-lanthanide complexes. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Tese

Desenvolvimento de metodologia para isolamento e caracterização de microplásticos em iogurtes

2026-07-27T12:58:42Z

Título: Desenvolvimento de metodologia para isolamento e caracterização de microplásticos em iogurtes Autor: Souza, Franciele Pereira de Primeiro orientador: Costa, Marcos Antônio da Silva Abstract: Microplastics (MPs) are polymeric particles smaller than 5 mm that, due to their high production and small size, are easily dispersed in the environment. As a consequence, they are found in foods such as honey and milk, and in the human body, such as in blood and even breast milk. This study aimed to develop a method to investigate the presence of microplastics in yogurts. The samples were obtained from commercially available yogurts of different brands and flavors, including strawberry, natural, natural skimmed, and Greek yogurt, with polypropylene and polystyrene packaging. The standard samples underwent a digestion test to find the best methodology for digesting and isolating the microplastics. Optimization of the sample isolation process with 10% (w/v) KOH indicated optimal conditions of 1.0 g of sample, with a KOH volume of 100 mL, and a digestion time of 24 h, resulting in efficiencies consistently above 99%. Recovery tests validated the methodology, showing high rates for PS1 (93.00±2.20%), PS2 (97.00±2.01%), PP1 (93.20±4.03%), and PP2 (97.06±4.20%). The best methodology found was applied to the samples and analyzed with optical microscopy to visualize the particles in the filter, and then analyzed by Fourier transform infrared microspectrometry (μ-FTIR). The method developed in this research was able to detect and identify the microplastics present in commercial yogurt samples and contribute to other studies in the area, providing more information about a new problem and potentially contributing to future research. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação

Síntese e caracterização de compósitos de redes metalorgânicas de Cério com TiO2 para remediação de águas por fotocatálise

2026-07-15T13:18:37Z

Título: Síntese e caracterização de compósitos de redes metalorgânicas de Cério com TiO2 para remediação de águas por fotocatálise Autor: Silva, João Victor Viana da Primeiro orientador: Gonçalves, Marcos Vinicius Colaço Abstract: Metal-organic frameworks (MOFs) are a relevant class of materials which gained prominence during the last 20 years. The flexible design of their electronic, molecular and crystalline properties branched in heterogeneous photocatalysis, one of the most sustainable methods for water remediation. Heterogeneous photocatalysis is considered one of the most sustainable and efficient alternatives for the degradation of organic micropollutants on aqueous media. Among the different archetypes, UiO-66 possesses interesting properties such as chemical stability and high surface area. Ce-UiO-66 is able to utilize a wider range of solar radiation spectrum and favorable electronic properties for photooxidation, spontaneous redox pair and besides structural matters into the Ce-MOFs synthesis. A typical material, TiO2 presents high oxidative potential but known limitations such as necessity of ultraviolet solar radiation and low specific surface area. The combination of both materials enhances the capability of removing pollutants by the design of composites in a heterojunction. This work proposes the synthesis of new materials based on Ce-UiO-66 and TiO2 for the photocatalysis of the model pollutant methylene blue. MOFs obtained in longer synthesis duration presented more pronounced adsorption and photocatalytic removal, mainly the 4-hour MOF which presented a second Ce(III) phase. Composites with lower TiO2 loading exhibited enhanced pollutant removal altogether with interesting features: 21 nm particle diameter revealed by Transmission Electron Microscopy, the presence of Ce(III)/Ce(IV) pair is suggested by X-Ray Absorption Spectroscopy. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação

A influência da concentração do HPA antraceno no gafanhoto semiaquático Cornops aquaticum associado à sua planta hospedeira Eichhornia crassipes na Amazônia Oriental

2026-07-08T15:19:02Z

Título: A influência da concentração do HPA antraceno no gafanhoto semiaquático Cornops aquaticum associado à sua planta hospedeira Eichhornia crassipes na Amazônia Oriental Autor: Lima, Wilson Figueiredo de Primeiro orientador: Calderari, Mônica Regina da Costa Marques Abstract: This study evaluated trophic transfer and ecotoxicological effects of the polycyclic aromatic hydrocarbon (PAH) anthracene in an experimental aquatic system involving the aquatic macrophyte Eichhornia crassipes and the semiaquatic grasshopper Cornops aquaticum in Eastern Amazonia. The objective was to assess anthracene uptake, accumulation, bioaccumulation, and toxicity along the food chain, as well as to determine its influence on grasshopper survival and biological responses. To this end, controlled experiments were conducted using different concentrations of anthracene added to the water, with plants and grasshoppers exposed for defined periods. Quantification of the contaminant in plant compartments (leaves, petioles, and roots) and in grasshoppers (males and females) was performed by high-performance liquid chromatography with a diode array detector (HPLC–UV-DAD) following Soxhlet extraction. The results demonstrated that E. crassipes exhibited a high capacity for anthracene uptake and retention, with predominant accumulation in the roots, reaching maximum concentrations of 839.94 µg.g⁻¹. This pattern indicated that hydrophobic sorption was the primary mechanism governing contaminant retention, resulting in limited translocation to aerial tissues. Nevertheless, the presence of anthracene in leaves was sufficient to enable trophic transfer to C. aquaticum via dietary exposure. A strong positive correlation was observed between foliar anthracene concentrations and insect body burden (r = 0.89; p < 0.001), confirming active bioaccumulation. The highest mean concentrations were recorded in females (115.42 µg.g⁻¹), suggesting the influence of physiological and metabolic factors, possibly associated with detoxification enzymes such as cytochrome P450. Toxicity assays revealed a pronounced toxic effect, with a progressive reduction in survival as anthracene concentration and exposure rate increased. At the 0.10 g experiment, the greatest impact was observed, with only 10% of individuals surviving until the end of the experiment. Sex-related differences were evident, with females showing greater initial resistance at low doses, whereas males exhibited higher tolerance at elevated concentrations. Chemical analyses indicated wide variation in anthracene body burden among insects (0 to 4,022 µg.g⁻¹). The relationship between daily dose and survival revealed a critical metabolic threshold between 450 and 550 µg.g⁻¹.day⁻¹, associated with a sharp increase in mortality, indicating that daily exposure rate is a key determinant of toxicity, more relevant than the total amount accumulated at the end of the exposure period. It is concluded that E. crassipes simultaneously acts as a biogeochemical filter, sink, and secondary reservoir of anthracene, while C. aquaticum exhibits high sensitivity and predictable responses to contamination, reinforcing its potential as a trophic bioindicator of anthracene pollution. This study contributes to the understanding of bioaccumulation processes, trophic transfer, and environmental risk of persistent organic contaminants, and highlights the potential of these species as models for phytoremediation and biomonitoring studies in tropical aquatic ecosystems. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Tese