Correa P.C.,Federal University of Viçosa |
Resende O.,IF Goiano |
Garin S.A.,Public University of Navarra |
Jaren C.,Public University of Navarra |
De Oliveira G.H.H.,Instituto Federal Of Brasilia
Engenharia Agricola | Year: 2011
The present study aimed to determine the volumetric shrinkage rate of bean (Phaseolus vulgaris L.) seeds during air-drying under different conditions of air, temperature and relative humidity, and to adjust several mathematical models to the empiric values observed, and select the one that best represents the phenomenon. Six mathematical models were adjusted to the experimental values to represent the phenomenon. It was determined the degree of adjustment of each model from the value of the coefficient of determination, the behavior of the distribution of the residuals, and the magnitude of the average relative and estimated errors. The rate of volumetric shrinkage that occurred in bean seeds during drying is between 25 and 37%. It basically depends on the final moisture content, regardless of the air conditions during drying. The Modified Bala & Woods' model best represented the process.
Correa P.C.,Federal University of Viçosa |
de Oliveira G.H.H.,Instituto Federal Of Brasilia |
Baptestini F.M.,Federal University of Viçosa |
Diniz M.D.M.S.,Federal University of Viçosa |
da Paixao A.A.,Federal University of Viçosa
Chilean Journal of Agricultural Research | Year: 2012
Infrared dehydration is more advantageous than the convective system under similar conditions, and studying this process is important to further develop equipment and procedures. Thus, the aim of this work was to study the dehydration process of tomato (Solanum lycopersicum L.) slices obtained by infrared drying at three different maturity stages throughout two different procedures: Firstly, the drying model was determined by applying the mass and energy balances under wet bulb temperature for the constant drying rate period and secondly, the mass effective diffusion coefficient was determined throughout the experimental data and the theory of diffusion of the liquid phase for the decreasing drying rate period. Tomato fruits cv. Santa Cruz were used. Three maturity stages were selected: green (stage 1), orange (stage 2), and red (stage 3). Mathematical models frequently used to represent drying of agricultural products were fitted to the experimental data of tomato drying. The effective diffusion coefficient was obtained by adjusting the liquid diffusion mathematical model to the experimental data of the descending period of dehydration. The two-term model was the best one to represent the tomato dehydration process. The critical moisture content for tomato dehydration was 2.97 kgw kgdm -1. There is an initial dehydration period in which the drying rate reaches its maximum (approximately 1.05 kgw kgdm -1, about 3 min). Three different methods were used to obtain values of the effective diffusion coefficient, including the finite element method, which had the lowest values for the least square sum of deviation 1.00 × 10-7 m2 s-1. The global coefficient of heat transfer was 12.45 W m-2K-1, and the global coefficient of mass transfer was 0.0105 m s-1.
de Oliveira G.H.H.,Instituto Federal Of Brasilia |
Correa P.C.,Federal University of Viçosa |
de Souza Santos E.,Federal University of Viçosa |
Treto P.C.,Federal University of Viçosa |
Diniz M.D.M.S.,Federal University of Viçosa
International Journal of Food Science and Technology | Year: 2011
The desorption isotherms and thermodynamic properties of cocoa beans were obtained during the drying process of this product. The isotherms were determined by dynamic method for various temperature (25, 35, 45 and 55°C) and relative humidity (RH) conditions (30, 40, 50, 60, 70 and 80%). Equilibrium moisture content data were correlated by the Guggenheim-Anderson-de Boer (GAB) model, which presented good fit to the data, according to statistical procedures. Equilibrium moisture content ranged from 5.90 to 16.67d.b.; it increased with an increment in the RH and decreased with increased temperature at a constant RH. Enthalpy values for each model coefficient were encountered, ranging from -90.05 to 545.96kJkg-1. The integral isosteric heat of desorption and differential entropy increased with decreased equilibrium moisture content, a tendency also found for Gibbs free energy. © 2011 The Authors. International Journal of Food Science and Technology © 2011 Institute of Food Science and Technology.
De Sousa H.C.,University of Brasilia |
Soares A.H.S.B.,University of Brasilia |
Costa B.M.,Instituto Federal Of Brasilia |
Pantoja D.L.,Federal University of Piauí |
And 3 more authors.
South American Journal of Herpetology | Year: 2015
Disturbance caused by anthropogenic fires are increasingly affecting the biodiversity of fire-prone ecosystems worldwide. The Cerrado biodiversity hotspot suffers higher deforestation rates than Amazonia and concentrates most of the burned areas in South America. To support adequate fire-management decisions in Cerrado, knowledge on the effects of altered fire regimes upon its animal populations is necessary. Based on a long-term, large-scale fire experiment, we investigated the effects of different fire regimes on the demography of the gymnophthalmid Micrablepharus atticolus, an endemic lizard of the Cerrado. Because M. atticolus is more abundant in open habitats, we predicted that frequent burns should favor its populations. Over eight years, we conducted a mark-recapture study using pitfall trap arrays in five 10 ha plots of cerrado sensu stricto, subjected to prescribed burns. Using generalized linear mixed-models of time series data and an information theoretic approach to select demographic models, we describe the life history of M. atticolus and assess the response of apparent survival, detectability, and recruitment to burn regimes and climate variation. Micrablepharus atticolus has an annual life cycle, with complete annual population turnover; breeding takes place during the dry season, when activity is higher, and hatchlings appear in the wet season. Apparent survival, detectability, and recruitment increased in the short-run after the passage of fire in all experimental plots. In the long run, however, both fire-suppression and more severe fire regimes were seemingly detrimental, presumably by affecting microclimatic conditions and food availability. Short-term studies may not adequately describe the effects of fire on the demography of lizard populations. Adequate fire management is warranted for biodiversity conservation in Cerrado, both inside and outside protected areas, including a reduction in the frequency and severity of burns in open physiognomies and controlled, patch mosaic fires to prevent excessive fuel accumulation in denser physiognomies. © 2015 Brazilian Society of Herpetology.
da Silva R.A.,Instituto Federal Of Brasilia |
Quintela E.D.,Embrapa Arroz e Feijao |
Mascarin G.M.,Embrapa Arroz e Feijao |
Pedrini N.,CONICET |
And 2 more authors.
Journal of Invertebrate Pathology | Year: 2015
Eggs, nymphs (1st-5th instar) and adults of Tibraca limbativentris were challenged by conidial suspensions of its major fungal pathogen Metarhizium anisopliae in order to assess their susceptibility. The role of chemical defensive compounds from exocrine secretions produced by both nymphs and adults were examined for their participation on M. anisopliae infection. Although insect susceptibility to M. anisopliae followed a dose-dependent manner, adults followed by older nymphs displayed the highest resistance. Eggs were highly susceptible showing >96% fungal infection. Crude extracts isolated from metathoracic scent gland and dorsal abdominal glands of adults and nymphs, respectively, showed fungistatic effects by impairing spore germination, vegetative growth and sporulation. Gas chromatography-mass spectrometry analysis of these extracts revealed that the major components were short-chain hydrocarbons (C10-13) and unsaturated aldehydes. In vitro tests with the corresponding synthetic standards indicated compounds with greater antifungal activity including (E)-2-hexenal, (E)-2-octenal, and (E)-2-decenal, with the latter being the most deleterious to fungal fitness. We demonstrated that differential susceptibility of the rice stalk stink bug to M. anisopliae infection is age-specific and partly mediated by fungistatic properties of aldehydes, which are produced by scent glands of both nymphs and adults. © 2015 Elsevier Inc.
PubMed | CONICET, Instituto Federal Of Brasilia, Embrapa Arroz e Feijao and Federal University of Goais
Type: | Journal: Journal of invertebrate pathology | Year: 2015
Eggs, nymphs (1st-5th instar) and adults of Tibraca limbativentris were challenged by conidial suspensions of its major fungal pathogen Metarhizium anisopliae in order to assess their susceptibility. The role of chemical defensive compounds from exocrine secretions produced by both nymphs and adults were examined for their participation on M. anisopliae infection. Although insect susceptibility to M. anisopliae followed a dose-dependent manner, adults followed by older nymphs displayed the highest resistance. Eggs were highly susceptible showing >96% fungal infection. Crude extracts isolated from metathoracic scent gland and dorsal abdominal glands of adults and nymphs, respectively, showed fungistatic effects by impairing spore germination, vegetative growth and sporulation. Gas chromatography-mass spectrometry analysis of these extracts revealed that the major components were short-chain hydrocarbons (C10-13) and unsaturated aldehydes. In vitro tests with the corresponding synthetic standards indicated compounds with greater antifungal activity including (E)-2-hexenal, (E)-2-octenal, and (E)-2-decenal, with the latter being the most deleterious to fungal fitness. We demonstrated that differential susceptibility of the rice stalk stink bug to M. anisopliae infection is age-specific and partly mediated by fungistatic properties of aldehydes, which are produced by scent glands of both nymphs and adults.
Technical feasibility of the incorporation of rice husk ash, Sludge from water treatment plant and wood ash in clay for ceramic coating [Viabilidade técnica na incorporação de cinza de casca de arroz, Lodo de estação de tratamento de Água e cinza de lenha em massa cerâmica para revestimento]
de Medeiros E.N.M.,Instituto Federal Of Brasilia |
Sposto R.M.,University of Brasilia |
de Araujo Neves G.,Federal University of Campina Grande |
Menezes R.R.,Federal University of Campina Grande
Revista Escola de Minas | Year: 2014
This paper presents a technical feasibility analysis of the incorporation of Rice Husk Ash (RHA), Sludge from Water Treatment Station (SWTS) and Wood Ash (WA) in clay for the mass used in ceramic coating. The methodology involved analyzing the technological properties of various compositions. Samples were prepared for pressing, with compositions from 0 to 50% waste and 50 to 100% clay. The sintering was carried out in a muffle furnace. The properties studied were: solubility and leaching (environmental characterization), water absorption and rupture strength modulus. It was concluded that the best condition was the use of up to 25% of the residuals at temperatures of 1000 °C, 1100 °C and 1150 °C. © 2014, Escola de Minas. All right reserved.
Da Silva F.B.V.,University of Brasilia |
Da Silva F.B.V.,Instituto Federal Of Brasilia |
Oliveira F.A.,University of Brasilia |
Barbosa M.A.A.,University of Brasilia
Journal of Chemical Physics | Year: 2015
The thermodynamics and kinetics of the one dimensional lattice gas with repulsive interaction are investigated using transfer matrix technique and Monte Carlo simulations. This simple model is shown to exhibit waterlike anomalies in density, thermal expansion coefficient, and self-diffusion. An unified description for the thermodynamic anomalies in this model is achieved based on the ground state residual entropy which appears in the model due to mixing entropy in a ground state phase transition. © 2015 AIP Publishing LLC.
da Mata R.A.,Federal University of Goais |
Roque F.,Instituto Federal Of Brasilia |
Tidon R.,University of Brasilia
Natureza e Conservacao | Year: 2015
The relevant scales over which specific communities vary must be identified to address fundamental ecological questions and to advance the conservation of biological diversity. In this study, the variation among drosophilid assemblages associated with forests was quantified at a large temporal-spatial scale. Our results are based on data collected in four conservation units (CUs) in the Brazilian savanna across four seasons and two years. The primary component of variation occurred at the temporal scale: it was three times greater than that of the spatial scale. Significant variability was also found in the interaction between seasons and CUs. Measuring the temporal and spatial variability of drosophilid diversity in forests contributed to the improvement of the methodological framework supporting such assemblages as bioindicators and provided important insights into the mechanisms behind the dynamic patterns in time and space that ultimately can improve our understanding of Cerrado biodiversity. © 2015 Associação Brasileira de Ciência Ecológica e Conservação.
De Oliveira G.H.H.,Instituto Federal Do Sudeste Of Minas |
Aragao D.M.S.,Instituto Federal Of Brasilia |
De Oliveira A.P.L.R.,Instituto Federal Do Sudeste Of Minas Gerais |
Silva M.G.,Instituto Federal Of Brasilia |
Gusmao A.C.A.,Instituto Federal Of Brasilia
Brazilian Journal of Food Technology | Year: 2015
The drying of agricultural products is widely used throughout the world to diminish the moisture content of the product, making microbial growth and chemical and biochemical reactions difficult, enabling safe storage for longer periods and also reducing the volume and mass to be transported. The aim of the present work was to evaluate and model the drying process of strawberries (Fragaria L.) and obtain the thermodynamic parameters at three different temperatures (40, 50 and 60°C). Fruits purchased at CEASA-DF with an initial moisture content of 93% (w.b.) were used. The experimental data were fitted to six mathematical models commonly employed to represent the drying step. The activation energy for the drying of strawberries and also the entropy, enthalpy and Gibbs free energy were determined. The Logarithmic model was the one that best fitted the drying phenomenon of strawberry fruits, presenting values for the mean relative error between 7.59 and 8.48%, with an estimated standard error between 0.03 and 0.06 and determination coefficient between 99.93 and 99.95%. The enthalpy of the drying process decreased with increase in drying temperature, with values of-481.21,-564.35 and-647.49 J mol-1 for temperatures of 40, 50 and 60°C, respectively. The same trend occurred for entropy, with values of-238.35,-238.61 and-238.86 J mol-1 K-1 for the temperatures of 40, 50 and 60°C, respectively. Gibbs free energy increased with increase in temperature, attaining values of 74,159.75, 76,544.54 and 78,931.90 J mol-1 for the temperatures of 40, 50 and 60°C, respectively.