Principais Coleções do Repositório
Submissões Recentes
Utilização de agregados reciclados para produção de blocos de concreto
(Universidade Federal de Lavras, 2025-05-22) Rodrigues, Hellen Mara Alves Chaves; Martins, Maria Alice; Guimarães Junior, José Benedito; Amaral, Evelize Aparecida; Batista, Felipe Gomes; Arantes, Lorran de Souza; Silva, Cinthia Aparecida
The growing demand for sustainable solutions in the construction industry has driven research into the reuse of waste as an alternative to the extraction of non-renewable natural resources. In this context, the production of concrete blocks with recycled inputs is a promising strategy for mitigating environmental impacts while maintaining the technical performance required for structural and non-structural applications. The general aim of this thesis was to investigate sustainable alternatives for the production of concrete blocks, focusing on the partial replacement of natural aggregates with construction and demolition waste (CDW) and lignocellulosic waste from wood widely used in construction, such as pine and eucalyptus. The research was based on a broad theoretical survey of solid waste, public policies, the classification and reuse of materials, as well as the characterization of conventional concrete blocks and those produced with alternative materials. On this basis, experimental formulations were carried out to assess the physical, thermal and mechanical effects of incorporating waste into the cement matrix. Critical analysis of the data revealed that, in controlled proportions, the use of this waste can contribute to reducing the environmental impact of the construction sector, without significantly compromising the performance of the blocks. The results highlight the technical and ecological potential of this approach, encouraging the adoption of more sustainable and circular practices in the construction production chain.
Marco regulatório das organizações da sociedade civil e assistência social: a gestão de parcerias da rede socioassistencial de um município do Campo das Vertentes
(Universidade Federal de Lavras, 2025-09-29) Abreu, Kênia de Cássia; Valadão, José de Arimateia Dias; Cabral, Eloisa Helena de Souza; Cabral, Eloisa Helena de Souza; Lima, Renata Pedretti Morais; Alcantara, Valderí de Castro
Social assistance in Brazil has followed a long path before being consolidated as a public policy and a social right. Historically marked by philanthropic and religious practices, its structuring as a citizenship right was driven by the Federal Constitution of 1988 and consolidated through the creation of the Law of Social Assistance (LOAS, 1993), the National Social Assistance Policy (PNAS, 2004), and the Unified Social Assistance System (SUAS) in 2005. The participation of Civil Society Organizations (CSOs) in the provision of social assistance services has always been significant but characterized by fragile partnerships, lacking regulation and transparency. The enactment of Law No. 13.019/2014, known as the Regulatory Framework for Civil Society Organizations (MROSC), brought significant innovations by establishing specific legal instruments (terms of promotion, collaboration, and cooperation agreements), mandating public calls for proposals, emphasizing results, and strengthening social control. Given this context, this study aims to analyze the implementation process of the MROSC in the social assistance network of a municipality in the Campo das Vertentes region, seeking to understand the transformations, challenges, and continuities in partnerships between the State and CSOs at the local level. This is a qualitative and descriptive research study, with data collected through semi-structured interviews with representatives of CSOs, the partnership management sector of the Municipal Department of Social Development and Citizenship (SMDSC), and the Municipal Council of Social Assistance (CMAS). Data analysis was conducted using Braun and Clarke’s (2006) thematic analysis methodology, allowing the identification of five major themes and seventeen analytical codes. The results reveal important advances, such as the formalization of partnerships, greater legal security, transparency in financial transfers, and improvements in accountability. On the other hand, limitations were identified, such as the technical fragility of CSOs, operational difficulties in adapting to new procedures, lack of systematic training, political-party influence in partnership definitions, and institutional resistance to change. It was also observed that the network-based approach envisioned by the legislation faces obstacles in everyday practice, marked by asymmetrical relationships and discontinuities in interorganizational cooperation. It is concluded that, despite the advances promoted by the MROSC, its full implementation in medium-sized municipalities, like the one studied, requires ongoing investment in training, institutional structures, political commitment, and more horizontal and participatory coordination mechanisms.
Proteomic analysis of cryopreserved Prochilodus lineatus seminal plasma: effects of melatonin on sperm quality preservation
(Universidade Federal de Lavras, 2025-11-10) Lopes, Guilherme Antonio de Gouvêa; Murgas, Luis David Solis; Motta, Naiara Cristina; Madureira, Ana Paula; Carneiro, William Franco
This study evaluated the effects of melatonin supplementation on sperm cryopreservation and seminal plasma proteomics in the neotropical fish Prochilodus lineatus. Sperm Cryopreservation is a key technique for aquaculture and species conservation but often causes oxidative stress, structural damage, and metabolic impairment in sperm cells. In this study, sperm samples (n = 9 per group) were cryopreserved with or without 2 mM melatonin, followed by post-thaw analyses of motility, vigor, membrane integrity, morphology, and proteomic profile. Melatonin significantly improved sperm quality after thawing, increasing motility from 43.15 ± 16.95% to 65.72 ± 16.32% (p = 0.042), as well as straight-line velocity (VSL; 10.53 ± 4.19 to 16.57 ± 5.64 μm/s; p = 0.033) and average path velocity (VAP; 15.73 ± 5.48 to 22.90 ± 6.75 μm/s; p = 0.046), while curvilinear velocity (VCL; p = 0.075) and beat-cross frequency (BCF; p = 0.061) showed positive but non-significant trends. Morphological evaluation revealed a reduction in strongly coiled tails, whereas membrane integrity (42–84%) and total abnormality rates (49–51%) were unaffected. Proteomic analysis identified 1,238 proteins, including eight exclusively expressed under melatonin treatment, mainly associated with energy metabolism, antioxidant defense, and proteostasis. Melatonin upregulated enzymes related to ATP production, redox balance, and protein degradation, while downregulating proteins linked to cryo-induced damage. These findings demonstrate that melatonin exerts a multifaceted protective effect during sperm cryopreservation by preserving energy metabolism, reinforcing antioxidant capacity, maintaining structural and genomic integrity, and improving post-thaw motility. Overall, this study provides the most comprehensive proteomic dataset of P. lineatus seminal plasma to date and highlights melatonin as a promising additive for enhancing sperm cryopreservation protocols in aquaculture and conservation.
Desempenho biológico e reprodutivo de Tetrastichus howardi (Hymenoptera: Eulophidae) criado em hospedeiro alternativo
(Universidade Federal de Lavras, 2026-01-22) Souza, Maria Isabel Almeida; Marucci, Rosangela Cristina; Peñaflor, Maria Fernanda Gomes Villalba; Souza, Ivana Lemos
The mass rearing of natural enemies is a strategy that optimizes the use of biological control in agriculture. Tetrastichus howardi (Olliff, 1893) (Hymenoptera: Eulophidae) is a gregarious endoparasitoid that has stood out in the control of lepidopteran pests and can be reared on an alternative host, Tenebrio molitor L. (1758) (Coleoptera: Tenebrionidae). However, successive rearing on the same host may affect the reproductive characteristics of the insect and lead to population degeneration. In addition, reproductive strategies such as superparasitism, host exposure time, and energetic supplementation may ensure greater reproductive success. The objective of this research was to evaluate biological and reproductive parameters of T. howardi reared on T. molitor over successive generations. Five bioassays were conducted: (i) evaluation of the biological and reproductive characteristics of T. howardi on T. molitor across generations; (ii) different exposure times of the parasitoid to the host; (iii) reproductive capacity of T. howardi at low densities; (iv) evaluation of superparasitism strategies; and (v) supplementation of parasitoid females with a honey and water solution. The following parameters were evaluated: parasitism and emergence rates, total progeny number, number of females and males, sex ratio, life cycle, and longevity. For insect counting, a stereomicroscope was used, and sex determination was performed based on antennal morphology. All experiments were analyzed using the R software (R Core Team, 2024), version 4.4.1. Generalized Linear Models (GLM) were applied, with a quasi-Poisson distribution used for count data, a binomial distribution for parasitism and emergence rates, and beta regression for sex ratio, all considering a 5% significance level. The results demonstrated that T. howardi parasitized and emerged in all evaluated generations; however, a reduction in the number of females was observed from the ninth generation onward. Between the fifth and sixth generations, biological and reproductive characteristics showed stabilization. An exposure time of 72 hours of the parasitoid to the host resulted in higher parasitism and emergence rates, as well as a greater number of offspring. No significant differences were observed among the tested parasitoid-to-pupa densities; however, pupal abnormalities were recorded under low parasitoid density conditions. Superparasitism increased parasitism and emergence rates compared with self-superparasitism and reduced the life cycle and longevity. Energetic supplementation increased parasitism and emergence rates and enhanced female longevity. It is concluded that T. howardi can be reared on T. molitor pupae without changes in reproductive characteristics for up to eight generations, that the ideal exposure time for better utilization of host resources and higher offspring production is 72 hours, that low densities should be avoided, that superparasitism strategies are important for the reproduction of this species, and that energetic supplementation of females is essential.