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Artigo
Cellulase adsorption on pretreated sugarcane bagasse during enzymatic hydrolysis
(2023-08-16) Moreira Neto, João; Machado, Daniele Longo; Bonomi, Antonio; Gonçalves, Vinicius Ottonio O.; Martins, Luiza Helena Silva; Costa, Josiel Martins; Costa, Aline Carvalho
The enzymatic hydrolysis of lignocellulosic biomass has become attractive for obtaining ethanol. Therefore, optimizing its conditions and revealing the main influencing factors are essential for an effective design. In this sense, this study evaluated the influence of cellulose conversion on the Langmuir isotherm parameters in cellulase adsorption on sugarcane bagasse pretreated by hydrothermal and organosolv methods. The adsorption isotherm assays were performed with commercial cellulase from Trichoderma reesei in Erlenmeyer flasks stirred at 150 rpm and 50 °C. Isotherms were determined for enzymatic hydrolysis substrate samples of hydrothermal bagasse (HB) and organosolv bagasse (OB) at 0, 1, 6, and 18 h, respectively. The Langmuir model represented well the experimental data for the cellulose–cellulase system.
The study of cellulase adsorption on HB and OB demonstrated that the maximum adsorption capacity (Emax) decreased during the reaction. From 0 to 18 h of hydrolysis, the value of Emax decreased from 37 ± 3 to 23 ± 2 mg cellulase/g HB and from 29 ± 1 to 25 ± 2 mg cellulase/g OB. Therefore, the adsorption of cellulase on a substrate varied during hydrolysis and its representation was expressed by an empirical equation related to the cellulose conversion and the Langmuir parameters.
Artigo
Cave-dwelling gastropods (Mollusca: Gastropoda) of Brazil, state of the art and conservation: a critical review
(2023-07-17) Ferreira, Rodrigo Lopes; Souza-Silva, Marconi; Zampaulo, Robson de Almeida
In 2022, Salvador and co-authors published an up-to-date list of gastropod species recorded from Brazilian caves. That list included 18 species (15 land and three freshwater species) that were considered by the authors to be restricted to caves (troglobitic). In this contribution we argue that only six of the species listed by them as truly troglobites can be classified in that category. We disagree with some characteristics listed by Salvador and co-authors to diagnose the species they classify as cave-restricted and argue that those species do not have truly troglomorphic traits (characteristic of subterranean habitats). Since the Brazilian legislation considers the degree of association with caves as a decisive attribute to preserve them, it is important to clarify the characteristics are sufficient and necessary for a species to be classified as cave-dependent.
Artigo
Case study of modeling covariance between external factors and sensory perception of coffee
(2023-08-18) Resende, Mariana; Borém, Flávio Meira; Cirillo, Marcelo Ângelo
Analysis and inference of sensory perceptions in coffee beverages are complex due to numerous random causes intrinsic to productivity, preparation, and especially consumer and/or taster subjectivity. In this context, latent variables often composed of a combination of other observed variables are discarded from conventional analyses. Following this argument, this study aimed to propose a model of structural equations applied to a database, geo-graphical indication of coffees in Serra da Mantiqueira, with a methodological contribution characterized by inclusion of a treatment effect, contemplated by different altitudes at which coffees were produced. From the methodology used, a covariance structure was estimated, and used in another statistical methodology to discriminate the effects. It is concluded that the proposed model proved to be advantageous for allowing the analysis of the relationship of latent variables, production and environmental variations, which are not considered in a sensorial analysis, and showed that, in fact, they influence the sensorial perception, for the coffees produced in the Serra da Mantiqueira region. The correlation structure generated from the covariance matrix adjust-ed by the model resulted in estimates that could be used in other statistical methodologies more appropriate to discriminate the effects, exemplifying the use of principal components.
Artigo
Carcass yield of Oreochromis niloticus deformed by inbreeding process evaluated by morphometry
(2023) Rezende, Cicero Eduardo; Galuppo, Matheus Ribeiro; Marçal, Danielle Cristina Pereira; Fernandes, Diana Carla Oliveira; Paulino, Renan Rosa; Freitas, Rilke Tadeu Fonseca
Genetic improvement is the main responsible for the increase in tilapia production in the last decades. However, the tools used in broodstock selection have increased the mating of related animals, and as a consequence, animals with morphometric anomalies have appeared. In view of the above, this work was carried out with the objective of evaluating the effect of body deformities on the meat yield of tilapia. A total of 106 animals from assisted reproduction of the UFLA tilapia breeding program were used, among which 53 had visible deformities. The animals were weighed, measured, and photographed with a digital camera and had their body areas measured using computer software. Afterward, the animals were slaughtered and the fillet from the left side was removed to measure weights and yields. On the right side, cuts were made to measure the meat volume in the carcass. The residues were weighed separately to analyze processing losses. Using the software R-studio the normality test was applied to all data and afterwards, the tests of means and correlations between morphometries and yields were performed. No morphometric differences were identified between the groups, but deformed animals showed smaller caudal areas and caudal peduncles and high correlations with fillet weight. However, normal fish showed higher fillet yield and lower residue production. It is concluded that the anomalies imply lower filet yield and a higher amount of processing residues
Artigo
Can anthropization govern the water and carbon dynamics? A case study of peatlands in Serra do Espinhaço Meridional, Brazil
(2020-05-20) Barral, Uidemar Morais; Silva, Alexandre Christófaro; Christófaro, Cristiano; Costa, Camila Rodrigues; Tassinari, Diego; Penafort Filho, Aparecido; Macedo, Geisla Mendes; Bispo, Diêgo Faustolo Alves; Gonçalves, Thamires Sabrina
Peatlands are ecosystems formed mostly by organic matter and water and constitute a particular type of free aquifer. They perform important hydrological functions by storing excess water during rainfall events, contributing to the baseflow of its rivers throughout the year. Its degradation affects the water table dynamics and influences the decomposition of organic matter content and the release of carbon into its waters. The water retention capacity may also be compromised and thus reduce the volume of water available downstream, especially in the dry season. This study aimed to evaluate the effects of anthropic interference on variations in groundwater level, water storage, and carbon flow in two tropical mountain peatlands, located at the head of the Araçuaí River, in Serra do Espinhaço Meridional, Minas Gerais State, Brazil. Level meters were installed in groundwater wells distributed on peatland zones located in a protected area (Natural Park) (Protected—TP) and outside the conservation unit (Anthropized—TA). Data were analyzed considering the daily rainfall recorded by an automatic weather station installed in the study area. From the data on precipitation and water table level variation, the specific yield (Sy) in the two peatlands was calculated. The observed flows and the mean monthly Sy on each groundwater well were correlated and their significance was verified using the t-test (p < 0.05). The relationship between the observed flow and the mean monthly values of Sy obtained for the groundwater wells was verified through multiple regression. The Sy correlated significantly with the flow in both peatlands (p < 0.05). Multiple linear regression showed a coefficient of determination (R²) of 0.92 in both peatlands, indicating a direct relationship between Sy and observed flow. The TP presented a 43% smaller variation in the water table, a 7% higher Sy, and a specific flow rate of 13% higher related to the TA. The peatland located in the protected area retains more water, with less variation in flow throughout the year, and releases less carbon in the water compared to the anthropized peatland. The results demonstrate that anthropization is causing peatland degradation, reducing its water-holding capacity and accelerating its carbon losses. In the medium term, these effects may lead to a drastic reduction in flow in the upper course of the Araçuaí River.