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Efeito dos extrativos nos processos de combustão e pirólise de resíduos lenhosos da Amazônia
(Universidade Federal de Lavras, 2025-02-26) Corrêa, Genilson Maia; Protásio, Thiago de Paula; Silveira, Edgar Amaral; Trugilho, Paulo Fernando; Dias Junior, Ananias Francisco; Oliveira, Tiago José Pires de
The use of residual biomass from forest management, in addition to being a source of renewable energy, is appropriate given the current need to reuse natural resources. Several factors can influence the utilization of these residues, including extractives, which can increase the calorific value of the wood and affect its density, permeability, and the yields of the pyrolysis process. However, studies on the effects of extractives during pyrolysis and combustion are not widely conducted on woody residues from native Amazon species. Therefore, the aim of this study is to evaluate the influence of extractives on wood characteristics and behavior during combustion and pyrolysis processes of woody residues. Woody biomass from five species derived from forest management residues in the Amazon were selected: Dinizia excelsa, Protium cf. altissimum, Parkia pendula, Inga spp., and Manilkara spp. The contents of holocellulose, cellulose, hemicellulose, and lignin in the woody residues were measured. The contents of total extractives, and extractives soluble in acetone, hot water, and cold water were also determined. Analyses of higher heating value and proximate chemical composition were conducted on both the raw material and the extractive-free material, using different removal methods. Thermogravimetric analysis was performed under oxidative and inert atmospheres, and combustion and pyrolysis indices were determined for both the raw and extractive-free materials. The species with the highest holocellulose content was Manilkara spp. (75.10% dry basis), while the lowest was Dinizia excelsa (58.07% db). For total lignin, values ranged from 27.61% db (Inga spp.) to 23,94% db (Dinizia excelsa.). Cellulose content ranged from 47.86% db (Manilkara spp.) to 36.68% db (P. altissimum). The lowest ash content was found in Inga spp. woody residues (0.52% db). Regarding extractives, the highest values were found in Manilkara spp. (5.91%) for cold water, and in D. excelsa (9.95% and 6.61%) for hot water and acetone, respectively. D. excelsa stood out due to its high total extractives content in the wood (16.38% db). In the proximate composition analysis, volatile matter content ranged from 79.35% (P. altissimum) to 85.54% (Inga spp.) in the raw material. Ash content ranged from 0.29% (D. excelsa) to 1.31% (Inga spp.), while fixed carbon ranged from 13.76% (Inga spp.) to 19.84% (D. excelsa), being influenced by the removal of extractives. There was no significant difference in the higher heating value (HHV) between the raw and extractive-free materials, with the highest value observed for D. excelsa (20.49 MJ/kg). In the DTG curves, differences were observed mainly in the maximum decomposition temperature, with the curve shifting to slightly higher temperatures after extractive removal. For D. excelsa and P. altissimum, extractives reduced thermal stability. For P. pendula and Manilkara spp., extractives had little effect on thermal degradation. In Inga spp., they slightly delayed degradation, with little impact on pyrolysis. The results indicate that prior removal of extractives from woody residues is feasible, without causing significant negative impacts on combustion and pyrolysis processes.
Irradiação gama e quitosana como substitutos do nitrito em mortadelas: efeitos da qualidade e crescimento de Clostridium botulinum
(Universidade Federal de Lavras, 2025-04-23) Magalhães, Onara Jandafet Sampaio Martins; Ramos, Eduardo Mendes; Ramos, Alcinéia de Lemos Sousa; Silva, Douglas Roberto G.; Andrade, Monalisa P. Dutra; Torres Filho, Robledo de Almeida
Nitrite is an additive that acts as an antioxidant, preservative (Clostridium botulinum) and added to products color, flavor and aroma of cured products. Although, nitrite under specific conditions can form N-nitrosamines (carcinogenic). This research suggests the replacement of total or partial nitrite by irradiation and chitosan, with the goal of reducing nitrosamine. In the 1°article, the aim was to assess the potential growth of inoculated C. botulinum (104 spores/g) in mortadella and its technological properties. Doses of irradiation (0,2,4,6KGy) were applied to the samples, which were added Chitosan (0 and 1.5%) and sodium nitrite (0, 50, and 150mg/kg), and kept refrigerated at 4°C for 30days. In the 1° day, the samples with chitosan (1,5%) and irradiation (2,4,6KGy) contributed to the non- growth of C. botulinum regardless of the presence of nitrite. The effect of irradiation was dose dependent (P<0.05). The samples were analyzed after 30 days and there was no growth potential of C. botulinum (δ < 0.5 log CFU/g), the combination of irradiation and chitosan remained efficient. Regarding color, the using of chitosan decreased L*, increased C*, and the curing color index (R650/570nm). There was an interaction between chitosan x nitrite level (P<0.05), it changed the cured color C* and h. The curing color index increased from 1.51 to 2.12 with nitrite level from 0 to 50mg/kg. Regarding texture, the using of chitosan decreased chewiness and springiness (P<0.05). And higher level of nitrite (50 and 150mg/Kg) increased hardness (P<0.05). Irradiation alone did not change color index or texture attributes (P<0.05). In the 2° article, the aim was to assess the physicochemical and quality properties of the samples when replaced nitrite by chitosan and irradiation during the storage at 4°C. Doses of irradiation were applied to the samples (0,2,4,6KGy), which were added chitosan (0 or 1.5%) and with nitrite levels (0, 50 and 150mg/Kg), they were kept refrigerated at 4°C for 60 days. The chitosan kept the TBARS values lower independent of irradiation application, chitosan worked as an antioxidant, without the use of nitrite and without its influence (P>0,05). The interaction among chitosan, nitrite level and storage were observed (P<0.05), resulting to the possibility of formation of a chitosan-nitrite complex that affected RNO2. The samples with chitosan and nitrite had higher values of RNO2 than nitrite (without chitosan), this data was contrary to the expected to be. Irradiation at 6kgy alone affected the RNO2 reducing its value, regardless of chitosan and storage time. Chitosan, nitrite level, irradiation and storage (P<0.05) had affected the color index (L*, C*, h°), in isolation or not by the interaction of chitosan x nitrite level x storage. The non-cured sample with chitosan were darker than cured (without chitosan). Irradiation (P<0,05), alone, interfered with the curing color. In conclusion, the application of chitosan (1.5%) and irradiation (2,4,6kGy) in partial or total could replace nitrite since the combination there is not disadvantageous changes that compromise the quality of mortadella. The use of chitosan with irradiation is recommended. However, it is necessary to study deeply the Chitosan-Nitrite complex.
Representações sociais em “Fogo e Sangue”: uma análise das personagens femininas sob a ótica dos estudos do discurso
(Universidade Federal de Lavras, 2025-03-07) Paula, Tawany Aparecida de; Amorim, Márcia Fonseca de; Vieira, Mauriceia Silva de Paula; Paris, Larissa Giacometti
Considering the importance of Discourse Analysis in understanding social and ideological dynamics, this study aims to investigate how the social representations of female characters are constructed in "Fire and Blood", by George R.R. Martin, exploring the discourses present in the work and the effects of meaning they promote. The research is anchored in the studies developed by Pêcheux (1997, 2014, 2015), with contributions from Orlandi (2020), among other authors, and uses Discourse Analysis as a theoretical tool to examine the discursivities that shape these characters and the social and ideological practices to which they are linked. Based on a qualitative study, this work highlights the importance of discursive formations and interdiscourse in the construction of meanings, reflecting on how preexisting discourses and specific ideological contexts influence the construction of female characters. The research also aims to reflect on the power relations and social structures present in these narratives. This study is organized into three theoretical chapters and one analysis chapter, in addition to the introductory chapter, research methodology, and final considerations. The first chapter addresses the theoretical assumptions of Discourse Analysis and its relevance for the investigation of the discourses that permeate female representations in the work. The second chapter explores the notions of gender, discussing the contributions of scholars such as Beauvoir (1967, 1970), Louro (2002, 1997), and other researchers, in addition to reflecting on the issues of identity, body, and power in female narratives. Finally, the third chapter presents a reflection on the fantastic literary genre and its specificities, using the works of Todorov (1992), Eco (1989, 1994), Vax (1972), and Rodrigues (1988) to support the discussion on the characteristics of this genre and its implications for social representations. Thus, it was possible to identify that the female characters present resistance to socially instituted patriarchy by assuming narratives that subvert the traditional gender representations imposed on them. This behavior of the women reveals a complex identity that breaks with discourses present in the social structure in which they are inserted. Furthermore, the results show that the discourses that permeate the work come from discursive formations that strengthen power inequalities and clash with other discursive formations that promote ideological ruptures that challenge conventional social structures.
Potencial inseticida do óleo essencial de eucalyptus globulus (myrtaceae) no manejo de euschistus heros (hemiptera: pentatomidae)
(Universidade Federal de Lavras, 2025-04-25) Rodriguez, Nazareth Del Carmen de Gracia; Marucci, Rosangela Cristina; Mendes, Simone Martins; Coelho, Rosamara Souza
Brazil is one of the largest soybean producers in the world. However, annual soybean production is affected by attacks by hytophagous insects such as the brown stink bug, Euschistus heros (Hemiptera: Pentatomidae), which causes direct and indirect damage to Brazilian soybean crops. The main method of controlling this pest is the use of chemical insecticides. However, in order to ensure public, food and environmental safety, the guarantee of safety in the production of plant-based foods becomes a specification evaluated by the
consumer and export market. Thus, the use of Essential Oils (EOs) is a promising alternative to conventional chemical control, due to their insecticidal properties and lower environmental impact. In this work, we investigated the insecticidal potential of Eucalyptus globulus EO in controlling insect pests through a literature review, covering its insecticidal properties and mechanism of action. Furthermore, we performed toxicity bioassays of E. globulus EO on E. heros nymphs and adults. The results revealed the oncentrations of E. globulus EO have an insecticidal effect on different developmental stages of E. heros, proving to be a potential tool in pest management.
Luz e ventilação natural impactam o crescimento e produção de compostos voláteis em Mentha piperita L. micropropagadas
(Universidade Federal de Lavras, 2025-02-24) Teixeira, Lurdeslaine Faria; Pinto, José Eduardo Brasil Pereira; Bertolucci, Suzan Kelly Vilela; Santos, Gustavo Costa dos; Botrel, Priscila Pereira
Mentha piperita L. is an herb used in cooking and present in some food products, perfumes, personal hygiene cosmetics and herbal medicines. Light intensity and quality generate specific physiological and morphogenic responses. In vitro natural ventilation enables the production of seedlings more resistant to acclimatization. The objective of this study was to evaluate the effect of light intensity, light quality and natural ventilation on the production of biomass and volatile compounds of micropropagated Mentha piperita. Nodal segments of 1 cm of in vitro established seedlings were inoculated. In the first experiment, the explants were grown under
light-emitting diodes (LEDs) at intensities of 20, 57, 78, 102 and 139 μmol m-2 s-1. In the second experiment, the explants were grown under white LED; blue; red; 70% blue: 30% red; 30% blue: 70% red; 50% blue : 50% red. In the third experiment, flasks using the natural ventilation system (SVN) with 1 (SVN1), 2 (SVN2), 4 (SVN4) porous membranes on the lids and without membrane (SVN0 - control) were used. All experiments were evaluated 30 days after inoculation, evaluating the length of the largest shoot and 2nd internode, number of shoots, leaf area, number of leaves, dry biomass of leaves, stem and root, in addition to the analysis of photosynthetic pigments, phenols, flavonoids and volatile chemical composition. The data were analyzed with the Sisvar software to compare the means, using the Scott-Knott test at a probability of 5%. In the first experiment, the plants under 20 μmol m -2 s -1 etiolated, but had a higher content of photosynthetic pigments. Cultivation under intensities of 78, 102 and 139 μmol m -2 s -1 indicated greater accumulation of dry biomass of leaves and total. The photon flux density did not influence the contents of menthofuran and pulegone. In the light quality experiment, red LED and 70%V: 30%A stimulated the growth of the stem and the 2nd internode. White, blue, 50%V: 50%A and 30%V: 70%A light benefited the production of dry biomass of leaves and roots. Shoots under the combinations of 50%V:50%A accumulated greater contents of total chlorophyll a and carotenoids. Red LEDs and 70%V: 30%A stimulated the production of menthofuran. In the natural ventilation experiment, the shoots showed greater shoot growth, accumulation of dry biomass of leaves, stem and roots in SVN4 and a higher content of photosynthetic pigments in SVN2. It was concluded that from 78 μmol m -2 s -1 , the seedlings of M. piperita develop a greater number of shoots, leaves and dry
biomass of the roots, in addition to growing more vigorously. It is recommended to grow the species under 70% V: 30% A LEDs to obtain seedlings with good shoot development, accumulation of dry biomass of the leaves, production of photosynthetic pigments and menthofuran, an important compound for the perfume industry. SVN4 provides vigorous growth of seedlings in vitro.