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O Repositório Institucional da UFSCar (RI UFSCar) é um sistema de informação que visa armazenar, preservar, organizar e disseminar amplamente a produção intelectual dos diversos setores e segmentos da comunidade da UFSCar, provendo o acesso aberto à informação produzida na instituição e registrada como científica, tecnológica, didática, artístico-cultural e técnico-administrativa.

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Conectividade funcional potencial em paisagens antropizadas: estrutura de resistência de caminhos de menor custo no retorno de Melipona quadrifasciata
(Universidade Federal de São Carlos, 2026-07-06) Furlan, Letícia Oliveira; Toppa, Rogério Hartung; http://lattes.cnpq.br/0673898572494729; https://orcid.org/0000-0002-1637-2840; http://lattes.cnpq.br/6221657747133329
Habitat fragmentation and the expansion of anthropogenic areas can compromise pollinator functional connectivity by altering landscape permeability and hindering their movement and survival. In this context, this study evaluated the functional connectivity of the native stingless bee Melipona quadrifasciata, commonly known as “mandaçaia”, in an anthropized landscape, investigating the influence of distance, seasonality, and the characteristics of potential corridors on bee return success and return speed. Release experiments were conducted during the four seasons of the year at five distances ranging from 500 to 2,500 m from the colony and were integrated with ecological corridor modeling based on least-cost paths generated from resistance surfaces built using land-use and land-cover data and the Normalized Difference Vegetation Index (NDVI). A total of 240 releases were performed, 60 in each season, of which 155 resulted in successful returns to the colony (64.6%). Return probability decreased significantly with increasing distance, ranging from approximately 79% at 500 m to 46% at 2,500 m, highlighting distance as the main limiting factor for movement. Seasonal differences were also observed, with lower return rates and slower return speeds in autumn and better performance during spring and summer. Potential corridors showed high spatial stability across seasons, with similarity indices exceeding 0.91 and maximum recurrence covering 87.36% of the total corridor area. However, the functionality of these corridors varied over time. Distance was the main factor associated with the probability of return, whereas landscape heterogeneity influenced the speed at which bees returned to the colony. The results indicate that the functional connectivity of M. quadrifasciata depends primarily on displacement distance but is also influenced by matrix functional quality and landscape heterogeneity. These findings reinforce the importance of simultaneously considering species movement capacity and matrix permeability in conservation strategies and landscape planning.
Expressão heteróloga e análise in silico da nova enzima halogenase “LavH” de Streptomyces lavendulae subsp. lavendulae
(Universidade Federal de São Carlos, 2026-07-08) Silva, João Pedro Nardachione; Silva, Adilson José da; http://lattes.cnpq.br/3447469350644179
Halogenases are enzymes capable of adding a halogen atom to an organic molecule. They are present in diverse genera of microorganisms and exhibit a wide variety of substrates and mechanisms of action, such as flavin-dependent halogenases (FDHs), which are capable of halogenating L-tryptophan using FADH2 (reduced flavin adenine dinucleotide) as a cofactor. There is industrial interest in prospecting for new halogenases, since industrial halogenation methods rely on toxic reagents, lack stereochemical specificity, and generate polluting and harmful byproducts. In this context, the present study reports, for the first time, the heterologous expression and in silico studies of the FDH from Streptomyces lavendulae subsp. lavendulae, herein named LavH. Its activity as an L-tryptophan halogenase with chlorine and bromine was confirmed in vivo in Escherichia coli cells through mass spectrometry, and excellent solubility was observed, unlike other halogenases, which are usually poorly soluble. Furthermore, to increase its viability for use in a biofactory, the enzyme was fused with the E. coli flavin reductase Fre, resulting in a highly insoluble fused enzyme, a finding that contrasts with existing literature. Thus, for in vitro assays, LavH and Fre were purified by affinity chromatography using Ni-NTA (nickel-nitrilotriacetic acid) columns. However, insufficient halogenated product was formed through the in vitro assay for quantification via HPLC, indicating that further assays with longer reaction times are required. For the in silico analyses, sequence alignment and the construction of a phylogenetic tree with other characterized FDHs were performed, revealing an evolutionary proximity to the enzymes BorH and ThaL. Subsequently, the three-dimensional structure of LavH was modeled using AlphaFold3, and molecular docking studies were carried out to elucidate the catalytic site structure and its halogenation preference for the L-tryptophan substrate. Ultimately, this study contributes to the understanding of the activity of this novel halogenase, its structure, and its evolutionary relationship with other enzymes, as well as its potential as an industrial enzyme and the challenges associated with this application.
Avaliação do lodo de estação de tratamento de esgoto como meio carreador e de proteção do agente de controle biológico Trichoderma harzianum para aplicação na agricultura
(Universidade Federal de São Carlos, 2026-07-08) Leite, Priscila Polaquini de Macedo; Souza, Clovis Wesley Oliveira de; Oliveira, Cauê Ribeiro de; http://lattes.cnpq.br/0781683628437007; http://lattes.cnpq.br/5321313558714462; https://orcid.org/0000-0003-4335-1460; https://orcid.org/0000-0002-8908-6343; http://lattes.cnpq.br/1550163732947528; https://orcid.org/0000-0002-2760-1346
The growing demand for food, driven by population growth, has intensified the need for more productive and environmentally sustainable agricultural systems due to the environmental and human health risks associated with conventional agricultural practices. In this context, biocontrol agents have emerged as promising alternatives to conventional agrochemicals, particularly fungi of the Trichoderma genus, which are widely recognized for their ability to control phytopathogens and promote plant growth. However, when applied to the aerial parts of plants, these microorganisms are sensitive to ultraviolet radiation and temperature fluctuations, factors that reduce their viability and effectiveness. Therefore, this study aimed to develop a sewage sludge-based granule for the incorporation of the biocontrol agent Trichoderma harzianum, evaluating its potential as a carrier matrix and as a physical barrier against UV radiation, for application either as a water-based suspension pulverized onto the phyllosphere or as whole granules applied directly to the soil. The granules were produced using sewage sludge and glycerol and were subsequently characterized regarding their physicochemical, mechanical, and biological properties. The material exhibited biocompatibility with the fungus, causing no inhibition halo formation and allowing fungal growth and colonization after the granulation process. Furthermore, the granules showed high mechanical resistance, with an average maximum compressive force of 21.46 ± 1.24 N and a mass loss of approximately 0.1% in the abrasion test. UV-Vis spectroscopy analysis revealed high absorption in the ultraviolet region, particularly between 260 and 350 nm, suggesting the potential of the material to act as a partial barrier against incident UV radiation. Overall, the results indicate that sewage sludge has potential as a carrier matrix for Trichoderma harzianum, contributing to the development of more sustainable agricultural formulations aligned with the principles of the circular economy, such as waste valorization and the return of nutrients to the soil.
Unraveling the morphology-structure-property relationship of silver orthovanadate p-semiconductor: experimental and theoretical investigation
(Universidade Federal de São Carlos, 2024-09) Cruvinel, Guilherme Henrique; de Oliveira, Regiane Cristina; de Oliveira, Marisa Carvalho; Pinatti, Ivo Mateus; Ribeiro, Renan Augusto Pontes; Longo, Elson; http://lattes.cnpq.br/2599129475801660; http://lattes.cnpq.br/4418790685669021; http://lattes.cnpq.br/1590009041985449; http://lattes.cnpq.br/8338530279475392; http://lattes.cnpq.br/3169714304604637; http://lattes.cnpq.br/9848311210578810
Silver vanadate (Ag3VO4) is considered one of the most important semiconductors. It finds practical applications in electrochemical cells, as bactericidal and virucidal agents, in photocatalysis, and environmental remediation. Despite the impressive experimental progress, the dependence of the properties of a material is strongly linked to its chemical composition and structure. In this sense, the peculiar physical-chemical properties of the vanadate's class have become important. However, the fundamentals of structure in this material remain poorly understood, and the theoretical insight into the morphology linked to its properties is completely missing. In the present study, different synthesis times were tested in the obtention of Ag3VO4 crystals by the microwave-assisted hydrothermal method, and their properties were discussed based on experimental results and quantum mechanics simulations. Structural characterizations (XRD, Raman and UV–vis spectroscopy, FE-SEM, and TEM analyses) confirmed the material order at short, medium, and long-range. Theoretical calculations contributed to identifying the atom distribution in the structure, nature of the type of electronic transition, and density of states present in the valence and conduction bands. The topological analysis of the electron density indicated transit chemical interactions and unexpected argentophilic interactions, and Mulliken, Hirshfeld and Bader population analysis provided the charges present on the chemical elements of the crystal. Predicted theoretical surface shapes and their stabilities were evaluated along with FE-SEM images.
Análise Comparativa entre Exposição Direta a Índices e Estratégias com Opções sob Diferentes Regimes de Mercado
(Universidade Federal de São Carlos, 2026-07-08) Schmidt, Augusto Paulo; Gomes, Vinicius Tribuzi Rodrigues Pinheiro; http://lattes.cnpq.br/5519527278619089
This work proposes a comparative analysis between direct exposure to market indices and the use of options strategies, combining a theoretical approach based on simpliﬁed scenarios with an empirical study on real S&P 500 options data. In ﬁnancial markets, the decision between maintaining a position in the underlying asset or using derivative instruments involves relevant considerations related to potential return, capital protection, payoﬀ asymmetry, hedging cost, and sensitivity to variables such as volatility and the passage of time. The study begins with a historical contextualization of the evolution of ﬁnancial markets and the emergence of derivatives, followed by the theoretical foundation necessary to understand options, their Greeks, and the arbitrage pricing principles underlying the Black-Scholes-Merton model. Building on this foundation, three valuation methodologies are compared for the same position in out-of-the-money calls: full repricing via Black-Scholes- Merton (Full Valuation), the traditional local Delta-Gamma approximation, and an extension proposed in this work, in which gamma is adjusted as a function of the underlying asset’s proximity to the strike. These three methodologies are then confronted with real daily closing data of SPX options throughout 2023, organized into three 90-day windows with distinct market regimes, under a risk equalization criterion that calibrates the size of the options position by the expected loss equivalent to that of a direct position in the index. The results show that the advantage of the real option over the spot, when it exists, is concentrated in speciﬁc time windows and is not sustained throughout the analyzed horizon, outperforming the index return in only between 7% and 27% of the tested vertices, depending on the market regime. The Delta-Gamma approximations, by freezing sensitivities at the initial instant, overestimate the real result in more than 80% of cases, as they fail to incorporate the time decay or the implied volatility variation observed in the market. It was also found that, during periods of index decline, the options structure acted more consistently as a loss-limiting instrument than as a gain ampliﬁer. It is concluded that the convexity of OTM options is an economically real mechanism, but its conversion into a net advantage over direct exposure depends critically on the timing of evaluation and on the simpliﬁcations adopted by each methodology.