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Síntese e caracterização óptica de filmes de poli(fluoreto de vinilideno) dopados com urucum (Bixa orellana L.)

2026-10-22T05:07:43Z

Título: Síntese e caracterização óptica de filmes de poli(fluoreto de vinilideno) dopados com urucum (Bixa orellana L.) Autor(es): Silva, Thais dos Santos Primeiro Orientador: Falcão, Evaristo Alexandre Abstract: In this work, pure poly(vinylidene fluoride) (PVDF) films and PVDF films doped with 1, 2, 3, 4, and 5% annatto (Bixa orellana L.), designated PVDF/URU, were prepared using N,N-dimethylformamide (DMF) solution processing. The films were characterized by Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible absorption spectroscopy (UV Vis) to evaluate the incorporation of the natural material into the polymer matrix and its influence on the vibrational and optical characteristics of PVDF. The FTIR spectra showed the preservation of the main characteristic bands of the polymer and the presence of contributions compatible with organic constituents of annatto, including carbonyl groups, oxygen-containing groups, and conjugated systems. The relative β-phase fraction was 71.79% for pure PVDF and remained between 72.77 and 74.77% for the doped films, indicating that annatto incorporation did not produce a significant change in this parameter. In contrast, the optical response was markedly modified. The absorption edge shifted from approximately 251 nm to as high as 645 nm, while the full width at half maximum of the absorption band increased from about 30 to 355 nm. Annatto incorporation also reduced transmittance and modified the absorption coefficient, extinction coefficient, and penetration depth. The indirect and direct optical bandgap values decreased from 4.93 and 5.48 eV, respectively, to approximately 1.85 and 2.15 eV for the PVDF/URU 5% film. The Urbach energy decreased from approximately 0.598 to 0.147 eV, indicating a narrowing of the localized-state tail near the absorption edge. Taken together, the results show that annatto produces pronounced changes in the optical response of PVDF films while the relative β phase fraction remains approximately constant, highlighting the potential of these materials for further studies involving optical, photonic, and ultraviolet-radiation-protection applications. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação

Aumento da absorção óptica e diminuição do bandgap de compósitos de PVDF/Curcuma longa Linn: técnica de UV-VIS

2026-10-22T05:07:38Z

Título: Aumento da absorção óptica e diminuição do bandgap de compósitos de PVDF/Curcuma longa Linn: técnica de UV-VIS Autor(es): Rodrigues, Eduardo de Sante da Silva Primeiro Orientador: Falcão, Evaristo Alexandre Abstract: This study investigated the influence of Curcuma longa Linn. (CLL) incorporation on the structural and optical properties of poly(vinylidene fluoride) (PVDF) films obtained by the casting method. For this purpose, PVDF films containing different concentrations of CLL were prepared. Subsequently, the samples were characterized by Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy. The FTIR spectra confirmed the incorporation of the plant material into the polymer matrix and indicated an increase in the relative percentage associated with the β phase up to a CLL concentration of 10 wt%. In the UV-Vis region, an increase in absorbance and a reduction in transmittance were observed with increasing CLL content. A shift in the absorption edge from 255 nm for pure PVDF to 414 nm for the composite containing 30% CLL was also observed. Additionally, the optical bandgaps associated with direct and indirect transitions decreased with increasing CLL concentration. Overall, the results demonstrate that the incorporation of the plant material produces significant changes in the structural organization and optical response of the system, highlighting the potential of PVDF/Curcuma longa Linn. composites as materials with composition-dependent tunable properties for optical and photonic applications. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação

“Avaliação da eficiência do revestimento de quitosana no "tempo de prateleira" dos ovos de galinha”

2026-10-16T05:07:24Z

Título: “Avaliação da eficiência do revestimento de quitosana no "tempo de prateleira" dos ovos de galinha” Autor(es): Tolentino, Nayane Ortega Primeiro Orientador: Arruda, Eduardo Jose de Abstract: Chicken eggs are particularly important, being sources of protein with high nutritional value and economic relevance; however, their quality progressively deteriorates during storage due to the exchange of water vapor and carbon dioxide through the porosity of the shell. This research evaluated the performance of chitosan coating formulations in the preservation of eggs stored under non-refrigerated conditions. In the first phase, 168 eggs were distributed between Control (Q0%) and treatments with chitosan at Q0.5%, Q1.0%, and Q1.5% (w/v), prepared in 5% acetic acid and applied by complete immersion, followed by immediate removal after complete coating of the surface. For seven weeks, mass loss, density, Haugh Unit, Yolk Index, yolk proportion, colorimetry, shell strength, and yolk integrity were evaluated using general linear models and robust standard errors (HC3) when necessary. In the second stage, physicochemical and biological characterizations of the eggshell–coating interface were performed using FTIR-ATR, UV-Vis, fluorescence, SEM/EDS, point determination of water activity, and a challenge assay with Salmonella Typhimurium. The week and treatment × week interaction effects were observed (p < 0.001), but there was no overall treatment effect in the average week (p = 0.394); Q1.5% showed a nearly zero slope that was lower than that of the Control (p = 0.003). For the percentage density loss, the main analysis was restricted to weeks 1 to 4, prior to method saturation: the interaction was significant (p < 0.001), and the three coated treatments showed lower slopes than the Control (p < 0.001), with no difference demonstrated between concentrations. The sensitivity analysis for weeks 1 to 5 preserved the direction of the result (interaction: p = 0.031). The Haugh Unit (n = 73) and the Yolk Index (n = 71) decreased with storage (p < 0.001), with no overall treatment effect or significant interaction. The yolk proportion (n = 73) showed a week effect (p = 0.012) and a borderline treatment × week interaction (p = 0.0495), but none of the slopes of the coated treatments differed from that of the Control. In colorimetry, L* showed treatment and interaction effects (p = 0.041 and p = 0.030), while a* and b* were predominantly influenced by time, and shell strength showed no treatment effect or interaction. FTIR-ATR indicated a superficial contribution of functional groups compatible with chitosan, preserving the predominant calcium carbonate bands. SEM and EDS demonstrated localized morphological changes and nitrogen detection only in the coated samples, with EDS being interpreted as semi-quantitative. Optical analyses revealed comparative changes in reflectance, transmittance, absorption, and fluorescence. In the microbiological assay, Q1.5% showed a greater descriptive reduction in the recovery of Salmonella Typhimurium on the eggshell, but the absence of individual counts per replicate prevented inferential comparison between treatments. Taken together, the chitosan formulations modified the surface interface of the eggshell and showed potential as a barrier to water and gas exchange, with more consistent quantitative evidence for maintaining density and specific evidence of a lower mass-loss slope in Q1.5%, without demonstrating universal superiority of one concentration in the evaluated attributes. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação

Coberturas de solo como estratégia de manejo inicial para formação de sistemas agroflorestais no município de Glória de Dourados – MS

2026-10-16T05:07:26Z

Título: Coberturas de solo como estratégia de manejo inicial para formação de sistemas agroflorestais no município de Glória de Dourados – MS Autor(es): Militão , Fernanda Turini Primeiro Orientador: Pereira , Zefa Valdivina Abstract: Environmental patterns have been significantly modified as a result of climate change, intensified by high emissions of greenhouse gases from industrial processes, urban lifestyles, and inappropriate land use. Unlike natural climate variations, which occur slowly and allow ecosystems to adapt, changes resulting from anthropogenic activities have occurred rapidly and intensely, causing environmental impacts on a global scale, including in agriculture, forestry, and water resources. In tropical forests, deforestation for land use, especially for agricultural and livestock activities, constitutes one of the main factors driving climate change. In the state of Mato Grosso do Sul, the expansion of agriculture and monocultures has intensified deforestation, contributing to high carbon emissions and aggravating regional environmental challenges. This scenario imposes challenges for ecological restoration, requiring adaptive strategies that integrate climatic limits, ecological vulnerability, and the functionality of restored ecosystems, while reconciling production and conservation. In this context, agroforestry systems emerge as an efficient alternative for integrating environmental restoration and agricultural production. Based on species diversity and the principles of ecological succession, these systems optimize land use, contribute to carbon sequestration, increase soil organic matter, and strengthen resilience to climate change. Thus, this study evaluated the initial development of eleven plant species under different types of soil cover (Napier grass, gliricidia, and eucalyptus), compared with a control treatment, in an area undergoing conversion to an agroforestry system in the municipality of Glória de Dourados, Mato Grosso do Sul, Brazil. A total of 352 seedlings (88 seedlings of each species) were randomly distributed at a spacing of 5 × 5 m. The mulches were applied in a 1 × 1 m area around each seedling. Plant development was monitored quarterly for 12 months through measurements of height, stem diameter, and survival assessment. The data were subjected to statistical analyses (ANOVA or KruskalWallis test) and to the calculation of the relative growth rate (RGR). Mortality varied among treatments, with a significant difference observed only between the eucalyptus and Napier grass mulches. Survival ranged from 40.63% (coconut) to 96.88% (acerola and white ipê), with high mortality observed for coconut seedlings (59.38%). No significant differences were found for growth variables. The RGR was higher for stem diameter (0.78 mm·mm⁻¹·year⁻¹) than for height (0.32 cm·cm⁻¹·year⁻¹). It was concluded that mulching plays an important role in maintaining seedling survival, although no significant effect on growth was observed during the 12-month period. Considering the advancement of environmental degradation and the limitations of conventional production systems, this study is expected to contribute to the understanding of practices that favor seedling establishment. Editor: Universidade Federal da Grande Dourados Tipo: Dissertação