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Efeito alelopático do extrato etanólico de Esenbeckia leiocarpa Engl. sobre a germinação e o desenvolvimento de plântulas de picão-preto (Bidens pilosa L.), amendoim-bravo (Euphorbia heterophylla L.) e capim-amargoso (Digitaria insularis (L.) Fedde).
(Universidade Federal de São Carlos, 2025-01-13) Barbosa, Lucas; Monquero, Patricia Andrea; https://lattes.cnpq.br/2766526793830455; https://orcid.org/0000-0002-9123-1861; https://lattes.cnpq.br/3027445638580407
The improper use of herbicides poses risks to both the environment and human health, in addition to contributing to the selection of tolerant weed species or resistant biotypes. In this context, allelopathy emerges as a promising alternative for weed management. In Brazil, Esenbeckia leiocarpa (commonly known as “guarantã”) is a native species with underexplored allelopathic potential. Aiming to identify alternatives to herbicide use, this study evaluated the allelopathic potential of the ethanolic extract of E. leiocarpa at different concentrations on the germination and development of Bidens pilosa, Euphorbia heterophylla, and Digitaria insularis. The experiment was conducted in a completely randomized design (CRD), in a 5 × 3 factorial arrangement, with five extract concentrations (0%, 2.5%, 5%, 10%, and 20%) and three weed species, with four replications. Evaluations included germination percentage (G%), root length reduction (mm), and signs of phytotoxicity in the tested weed species. A concentration of 2.5% already caused a significant reduction in the germination of all evaluated species. E. heterophylla showed slightly greater tolerance at lower concentrations; however, germination was completely inhibited for all species at concentrations equal to or above 10%. In the growth bioassays, root length of the seedlings was reduced by approximately 50% from the 5% concentration. Regarding phytotoxicity, concentrations of 10% or higher induced more than 80% phytotoxicity in all species, indicating severe toxicity. Among the tested species, D. insularis was particularly more sensitive, suggesting a higher susceptibility to the extract. The results indicate that the weed species responded differently to the E. leiocarpa leaf extract, which contains allelochemicals capable of interfering primarily with germination and early development. Therefore, E. leiocarpa shows promise as a bioherbicide for pre-emergence applications against the studied weed species.
Juntas híbridas TPU/AA6061-T6 moldadas por injeção com alta resistência interfacial via tratamentos de superfície baseados em silano
(Universidade Federal de São Carlos, 2025-01-13) Vasconcelos, Rayana Larissa; Canevarolo Júnior, Sebastião Vicente; https://lattes.cnpq.br/4153664441338178; https://orcid.org/0000-0002-7959-1872; Canto, Leonardo Bresciani; https://lattes.cnpq.br/7287108960864123; https://orcid.org/0000-0002-4138-005X; https://lattes.cnpq.br/2438420639837106; https://orcid.org/0000-0002-3345-9040; Marini, Juliano; Staffa, Lucas Henrique; Chinelatto, Marcelo Aparecido; Bianchi, Otávio; https://lattes.cnpq.br/4533610255047654; https://lattes.cnpq.br/2896049826673626; https://lattes.cnpq.br/2032752593664123; https://lattes.cnpq.br/0309287112277751
The fabrication of polymer-metal hybrid structures with high mechanical performance is related to the constituent materials of such structure, as well as the surface treatments applied to promote polymer-metal adhesion. In this work, thermoplastic polyurethane (TPU) and 6061-T6 aluminum alloy hybrid joints with high interfacial strength were developed by injection overmolding, with metal inserts treated consecutively by abrasion, oxidation and silanization, using different solution concentrations and pH, and a post-molding heat treatment. Metal inserts treated with 2% v/v and pH 10 presented a more hydrophilic surface compared to untreated metal inserts, which contributed to the subsequent polymer-metal adhesion. Analysis of the hybrid joints cross-section indicated the formation of an aluminum oxide layer and a partial TPU infiltration into microcavities on the metal surface. In shear testing, the hybrid joints showed an asymptotic mechanical behavior, in which the force increased continuously up to approximately 3 mm of displacement and, from that point on, remained nearly constant until failure. This suggests that, up to 3 mm of displacement, the measured force is equivalent to the interfacial strength of the hybrid joints. From 3 mm, the TPU intrinsic mechanical strength began to show a more considerable influence on the mechanical behavior of the hybrid joints, since as the material reached its yield point. From 3 mm until the moment of failure, the measured force became a function of the plastic deformation of the TPU. Therefore, the interfacial strength of the hybrid joints was greater than the intrinsic mechanical strength of the TPU, proving the efficiency of the surface treatments applied in the adhesion and performance of the TPU/AA6061-T6 hybrid joints.
Mercado livre de energia: avanços legislativos e impactos na transição energética brasileira
(Universidade Federal de São Carlos, 2025-01-13) Coimbra, Gabriela Oliveira; Tiezzi, Rafael de Oliveira; https://lattes.cnpq.br/7979063304544915; https://orcid.org/0000-0001-8682-7807
The free energy market in Brazil has been consolidating as a strategic mechanism to promote competitiveness and sustainability in the energy sector. With regulatory flexibility and incentives for the use of renewable sources, the Free Contracting Environment (ACL) has played a fundamental role in the sector’s modernization. This study analyzes the historical and regulatory evolution of the ACL, highlighting milestones such as Law No. 9.074/1995 and the recent Ordinances 514/2018 and 50/2022, which expanded consumer access to the free market. The research, qualitative and exploratory in nature, is based on a bibliographic review to understand the benefits and challenges of the ACL in the energy transition. Among the main benefits are cost reduction, freedom to choose suppliers, and encouragement of clean energy sources such as solar and wind. However, challenges such as the need for infrastructure investments, access regulation, and the intermittency of renewable sources still pose obstacles to market expansion. The analysis indicates that the full opening of the ACL, as proposed in bills like PL 414/2021, could democratize access to sustainable energy and increase sector competitiveness. However, this transition requires regulatory adjustments, rebalancing of sectoral charges, and measures to ensure security and stability in the electrical system. Finally, the study presents recommendations for strengthening the ACL, including regulatory improvements, consumer training, and incentives for distributed generation, aiming for a more efficient, accessible, and sustainable energy market.