Lettuce seeds treated with cerium and lanthanum aqueous solutions

Rare earth elements, or lanthanides, are important for plant growth and can benefit seeds vigor and germination, when incorporated to the seeds treatment. Thus, this study aimed at evaluating the initial performance of lettuce seeds submitted to treatments with cerium (Ce) and lanthanum (La), as well as their absorption. For this, lettuce seeds (Regina cultivar) were immersed in aqueous solutions of Ce or La, in different experiments, at the Ce concentrations of 0.0 mg L-1, 5.0 mg L-1, 10.0 mg L-1, 15.0 mg L-1, 20.0 mg L-1 and 25.0 mg L-1, and at the La concentrations of 0.0 mg L-1, 2.0 mg L-1, 6.0 mg L-1, 12.0 mg L-1, 20.0 mg L-1 and 30.0 mg L-1, for one hour. Tests for germination, first germination count, seedling dry weight and total, root and shoot lengths were carried out. The amount of Ce and La absorbed by seeds and seedlings were also evaluated. It was concluded that the treatment of seeds with Ce and La did not increase seeds germination, but stimulated seedlings growth. When these elements are applied to lettuce seeds as aqueous solution, they are absorbed by seeds and transferred to seedlings

Drying temperatures on physical integrity, physiological quality and chemical composition of rice seeds

The drying of seeds is essential for its production process, however, the temperature used can affect seeds quality. This study aimed at evaluating the effect of different temperatures on physical integrity, physiological quality and chemical composition of rice seeds. Four lots were arranged for each cultivar, being dried with the aid of the stationary method, by using the following temperatures: 32ºC, 38ºC, 44ºC and 50ºC. After each drying treatment, the physical integrity of seeds was analyzed, by evaluating its moisture content and fissures percentage. Physiological quality was evaluated with the aid of the germination test, first counting, electrical conductivity, accelerated aging, cold test, total length and dry mass of seedlings. The chemical composition of seeds was determined by evaluating their dry mass, crude protein and fiber and ethereal extract. The drying temperatures affected seeds quality, and when they increased (32-50ºC), the percentage of fissures in irrigated rice seeds also increased. Drying temperatures of 32ºC and 38ºC allowed the expression of seed quality, while the temperature of 50ºC reduced its physiological potential

Projeto e construção de um simulador de PCI para combustíveis sólidos pulverizados : características do equipamento

Pulverized coal injection (PCI) is a technique worldwide used in blast furnaces (BFs) to reduce coke consumption. Burning of pulverized coal injected into tuyeres of BFs takes place under medium pressure (up to 450 kPa), high flame temperatures (around 2500 K), very fast heating rates (105–106 K/s) and very short residence times, less than 40 ms. Since there are no standard tests for evaluation of coal combustibility at PCI conditions, lab scale injection rigs are usually employed for this purpose. This work shows relevant characteristics of the injection rig developed by LASID-UFRGS, which operates at automated injection mode. The main rig features are direct measurement of pressure and temperature inside the combustion zone during combustion process, temperature measurement with ultra-fast thermocouples (ms), high speed control and data acquisition (ms) and collection of both solid and gaseous combustion products. First results showed pressure and temperature evolution along throughout the combustion test, with and without sample, combustion gas composition and coal burnout for different coals. Experimental data statistics showed good repeatability for all tested coals.A injeção de carvão pulverizado (PCI) é uma técnica utilizada em altos-fornos (AFs) para reduzir o consumo de coque. A queima do carvão pulverizado injetado nas ventaneiras do AF ocorre em pressões médias (até 450 kPa), temperaturas de chama elevadas (cerca de 2500 K), taxas de aquecimento muito elevadas (105–106 K/s) e tempos de residência muito curtos, abaixo de 40 ms. Como não há testes padronizados para avaliação da combustibilidade de carvões nas condições de PCI, simuladores de combustão em PCI são comumente utilizados para esse fim. Este trabalho apresenta as características relevantes do simulador de PCI desenvolvido pelo LASID-UFRGS, que opera com pulso automatizado de injeção. As características principais do simulador são a medida direta de pressão e temperatura dentro da zona de combustão durante o, a medição de temperatura com termopares ultrarrápidos (ms), a aquisição de dados e controle em alta velocidade (ms) e a coleta dos produtos sólidos e gasosos da combustão. Os primeiros resultados mostraram a evolução da pressão e temperatura durante o pulso de injeção, com ou sem amostra, o grau de conversão (burnout) do carvão e a composição dos gases de combustão para diferentes carvões. A análise estatística dos dados experimentais demonstrou uma boa repetitividade para todos os carvões testados

Nonlinear dynamic analysis of a Stockbridge damper

The purpose of this work is to validate a nonlinear mathematical model (finite element method) for dynamic simulation of Stockbridge dampers of electric transmission line cables. To obtain the mathematical model, a nonlinear cantilever beam with a tip mass was used. The mathematical model incorporates a nonlinear stiffness matrix of the element due to the nonlinear curvature effect of the beam. To validate the mathematical model, the numerical results were compared with experimental data obtained on a machine adapted from cam test. Five different circular cam profiles with eccentricities of 0.25, 0.5, 0.75, 1.25, and 1.5 mm were used. Vibration data were collected through three accelerometers arranged along the sample. A good concordance was found between the numerical and experimental data. The same behavior was observed in tests of another Stockbridge damper excited by a shaker. The nonlinear behavior of the system was evidenced.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Ant Group Effects on the Insecticide and Dye Flow Among Atta sexdens rubropilosa (Hymenoptera: Formicidae) Workers

Social behavior has conferred many advantages upon insects. Allogrooming and self-grooming, frequently observed among leaf-cutting ants, help to prevent colony contamination by microorganisms and aid in the process of recognizing nest-mates, given the evidence that the grouping effect acts to modulate these behavioral parameters. For Ellis reason, the contamination dynamic was evaluated in workers of Atta sexdens rubropilosa by particles adhering externally to the tegument of their bodies, with and without the presence of insecticide added to dye in different groupings. The results demonstrate that although the dye had dispersed rapidly among workers in all groupings, it was eliminated efficaciously only in groups that utilized the dye without insecticide. When compared by the chi-square test (X(005)(2); 3) at 60 minutes only, the group containing the most individuals (128) presented significant values and at 120 minutes only the smallest group (16 individuals) did not present significant values, indicating that the greater the number of individuals the more rapidly it would be dispersed among nest-mates, thus elevating the importance of utilizing active ingredients with a delayed action in the control of leaf-cutting, ants, to avoid detection of insecticide by the colony and enable its propagation to all or most of the colony before triggering, the defense mechanisms of the colony.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq