Aplicação da metodologia de planejamento de experimentos para formulação de massas cerâmicas para telhas

Rio Grande do Norte State stands out as one great producer of structural clay of the brazilian northeastern. The Valley Assu ceramic tiles production stands out obtained from ilitics ball clays that abound in the region under study. Ceramics formulation and the design of experiments with mixture approach, has been applied for researchers, come as an important aid to decrease the number of experiments necessary to the optimization. In this context, the objective of this work is to evaluate the effects of the formulation, temperature and heating rate in the physical-mechanical properties of the red ceramic body used for roofing tile fabrication of the Valley Assu, using design of mixture experiments. Four clays samples used in two ceramics industry of the region were use as raw material and characterized by X-ray diffraction, chemical composition, differential thermal analysis (DTA), thermogravimetric analysis (TGA), particle size distribution analysis and plasticity techniques. Afterwards, they were defined initial molded bodies and made specimens were then prepared by uniaxial pressing at 25 MPa before firing at 850, 950 and 1050 ºC in a laboratory furnace, with heating rate in the proportions of 5, 10 e 15 ºC/min. The following tecnologicals properties were evaluated: linear firing shrinkage, water absorption and flexural strength. Results show that the temperature 1050 ºC and heating rate of 5 ºC/min was the best condition, therefore presented significance in all physical-mechanical properties. The model was accepted as valid based of the production of three new formulations with fractions mass diferents of the initial molded bodies and heated with temperature at 1050 ºC and heating rate of 5 ºC/min. Considering the formulation, temperature and heating rate as variables of the equations, another model was suggested, where from the aplication of design of experiments with mixtures was possible to get a best formulation, whose experimental error is the minor in relation to the too much formulations

A influência da adição de caulim, quartzo e feldspato potássico na formulação de massas cerâmicas para telhas: Modelo estatístico

The production of roof tiles in the state of Rio Grande do Norte accounts for around 60% of the total of ceramic pieces produced. There is a need for investment to improve quality and productivity, thereby promoting technological innovations. Accordingly, the aim of this study is to determine the effect of kaolin, potassium feldspar and quartz in two standard formulations, as well as the effect of sintering temperature on the technological properties of linear firing shrinkage, water absorption and bending rupture stress, by fitting the statistical model and using multiple linear regression to assess the relationship between technological properties and independent variables. The raw materials were characterized using the following techniques: X-ray fluorescence (XRF), X-ray diffraction (XRF), rational analysis (RA), differential thermal analysis (DTA) and granulometric analysis (GA). The test specimens were compacted by uniaxial pressure (25 MPa), dried in a stove at 110 ºC for 24 hours and sinterized at 850 ºC, 950 ºC and 1050 ºC and held isothermal for 30 minutes. The results obtained indicate that the addition of kaolin to two standard formulations (M and R) promoted a reduction in water absorption values and an increase in bending rupture stress values. The sintering temperatures for group M that resulted in the lowest linear firing shrinkage and water absorption values were 850 ºC and 950 ºC, respectively, and the highest bending rupture stress values were reached at a temperature of 950 ºC. In the case of group R, the sintering temperature that obtained the lowest water absorption and linear firing shrinkage values was 850 ºC, and the highest bending rupture stress values were attained at a temperature of 1050 ºC. This work explains the statistical approach used to fit the model that describes the relationship between the technological properties and percentage of kaolin, quartz and feldspar, as well as the models that enable predictions, provided that the lower and upper limits of the percentage of clay minerals, flux and quartz used in this study are respected. Statistica 6 software was used and results were obtained by stepwise forward regression

O treinamento nos valores da V200, FCpico e distância percorrida de cavalos da raça Árabe e Crioula

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lanthanum doped BiFeO3 powders: Syntheses and characterization

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ação de Polistes (Aphanilopterus) simillimus Zikán (Hymenoptera, Vespidae) no controle de Spodoptera frugiperda (Smith) (Lepidoptera, Noctuidae)

The corn is a plantation attacked by a lot of pests, mainly by Caterpillar Spodoptera frugiperda (Smith), producing serious damages in the plants, occasioning unproductiveness. Thus, the goal of this research was to verify the predation of Polistes simillimus (Zikán, 1951) wasps on this pest of a corn plantation using the wasps colonies as a efficient form of this pest management. The present research was developed in a area in the Piracicaba county, São Paulo (22º43'S, 47º38'W), during the period of november/1995-march/1996, introducing 20 P. simillimus colonies in artificial wood shelters around of 5 plots of com, to accompany the foraging activity of the wasps and the development of the wasps colonies. Spodoptera frugiperda (23,07%) was the main prey captured by the wasps and the average rate of capture was 1,54 preys/h. These data gave an estimation of reduction in the occurrence of S. frugiperda (77,16%), due mainly to the wasps action.

Efeito da adição simultânea de sementes e dopantes na microestrutura e propriedade dielétrica da cerâmica 0,93 PZN - 0,07 BT

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

BACTERIAL LEACHING OF URANIUM ORE FROM FIGUEIRA-PR, BRAZIL, AT LABORATORY AND PILOT-SCALE

A bacterial leaching program was carried out in order to evaluate the potential of applying this process to leach uranium from the ore of Figueira-PR, Brazil. The experiments were carried out in shake flasks, column percolation (laboratory and semipilot scale) and in heap leaching. In shake flasks and in column percolation experiments at laboratory scale, bacterial activity on the ore was confirmed: approximately 60% of uranium was leached, against around 30% in sterilized controls. Column percolation experiments at semipilot scale and heap leaching (850 tons of ore) showed uranium extractions of approximately 50%. In both experiments, a complementary sulfuric acid attack, after the bacterial leaching phase, was necessary to reach this level of uranium extraction.

Upconversion luminescence in transparent glass ceramics containing beta-PbF2 nanocrystals doped with erbium

Frequency upconversion luminescence in erbium-doped PbGeO3-PbF2-CdF2-based transparent glass ceramics (TGC) under 980 nm infrared excitation is investigated. Upconversion emission signals around 410, 525, 550, 660, and 850 nm were generated and identified as due to the H-2(9/2) H-2(11/2), S-4(3/2), and F-4(9/2) transitions to the I-4(15/2) ground-state, and S-4(3/2)-I-4(13/2), respectively. The erbium ions excited-state emitting levels were populated via a combination of stepwise ground-state absorption (GSA), excited-state absorption (ESA), and cross-relaxation processes. The results also disclosed that both blue (410 nm) and red (660 nm) upconversion emission signals in the transparent glass ceramic sample presented twice as much intensity as compared to its vitreous counterpart. (C) 2003 Elsevier B.V. All rights reserved.

Influence of seed particle frequency on the phase formation and on the microstructure of 0.88 PZN-0.07 BT-0.05 PT ceramic

The Pechini method as well as the simultaneous addition of seeds particles and dopant solutions of BaTiO3 (BT) and PbTiO3 (PT) were used to prepare the perovskite phase 0.88 PZN-0.07 BT-0.05 PT. To study the influence of seed particle frequency on the synthesis of the PZN ceramic, two ranges of seed particle size were used: the range from 30 to 100 nm, termed small seed particles (frequency of 10(15) particles/cm(3)); and the range from 100 to 900 nm, termed large seed particles (frequency of 10(13) particles/cm(3)). The crystalline nuclei size influenced the calcining process, the sintering process and the microstructure. Samples prepared with lower seed frequency displayed more amount of pyroclore phase, need higher temperatures for sintering and showed a more heterogeneous microstructure with poor dielectric properties. (C) 2000 Elsevier B.V. Ltd and Techna S.r.l. All rights reserved.

Bacterial leaching of uranium ore from Figueira-PR, Brazil, at laboratory and pilot scale

A bacterial leaching program was carried out in order to evaluate the potential of applying this process to leach uranium from the ore of Figueira-PR, Brazil. The experiments were carried out in shake flasks, column percolation (laboratory and semipilot scale) and in heap leaching. In shake flasks and in column percolation experiments at laboratory scale, bacterial activity on the ore was confirmed: approximately 60% of uranium was leached, against around 30% in sterilized controls. Column percolation experiments at semipilot scale and heap leaching (850 tons of ore) showed uranium extractions of approximately 50%. In both experiments, a complementary sulfuric acid attack, after the bacterial leaching phase, was necessary to reach this level of uranium extraction.

Optimization of yogurt production using demineralized whey

The effect of three independent fermentation variables: demineralized whey powder (0.0; 1.5 and 3.0%), lactic culture concentration (1.0; 2.0 and 3.0%) and mix treatment temperature (85; 90 and 95°C) was studied. Fermentation time to reach pH 4.3, instrumental consistency and appearance, visual consistency and taste of the product were evaluated. Product consistency increased as mix treatment temperature increased and demineralized whey powder decreased. The powder had a stronger influence on instrumental consistency than did temperature. Appearance was better when whey powder was used at 1.4 to 1.6%. Visual consistency decreased as whey powder increased but addition of demineralized whey powder did not negatively affect yogurt flavor.

CARISPLAN Abstracts: 07-001

Contiene resumenes bibliograficos de documentos sobre planificacion y desarrollo en el Caribe, recogidos y procesados en el marco del Sistema de Informacion del Caribe.

Functional Redundancy and Complementarities of Seed Dispersal by the Last Neotropical Megafrugivores

Background: Functional redundancy has been debated largely in ecology and conservation, yet we lack detailed empirical studies on the roles of functionally similar species in ecosystem function. Large bodied frugivores may disperse similar plant species and have strong impact on plant recruitment in tropical forests. The two largest frugivores in the neotropics, tapirs (Tapirus terrestris) and muriquis (Brachyteles arachnoides) are potential candidates for functional redundancy on seed dispersal effectiveness. Here we provide a comparison of the quantitative, qualitative and spatial effects on seed dispersal by these megafrugivores in a continuous Brazilian Atlantic forest. Methodology/Principal Findings: We found a low overlap of plant species dispersed by both muriquis and tapirs. A group of 35 muriquis occupied an area of 850 ha and dispersed 5 times more plant species, and 13 times more seeds than 22 tapirs living in the same area. Muriquis dispersed 2.4 times more seeds in any random position than tapirs. This can be explained mainly because seed deposition by muriquis leaves less empty space than tapirs. However, tapirs are able to disperse larger seeds than muriquis and move them into sites not reached by primates, such as large forest gaps, open areas and fragments nearby. Based on published information we found 302 plant species that are dispersed by at least one of these megafrugivores in the Brazilian Atlantic forest. Conclusions/Significance: Our study showed that both megafrugivores play complementary rather than redundant roles as seed dispersers. Although tapirs disperse fewer seeds and species than muriquis, they disperse larger-seeded species and in places not used by primates. The selective extinction of these megafrugivores will change the spatial seed rain they generate and may have negative effects on the recruitment of several plant species, particularly those with large seeds that have muriquis and tapirs as the last living seed dispersers. © 2013 Bueno et al.

Modelação das fibras musculares e efeitos na composição corporal de ratos submetidos a diferentes protocolos de treinamento físico

Pós-graduação em Fisioterapia - FCT

Avaliação do efeito do extrato hidroalcóolico de Myrcia bella cambess na dor aguda e na inflamação em modelos experimentais de roedores

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)