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Search Results: 1 - 10 of 599807 matches for " Gasparetto C.A. "
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A numerical solution for the entrance region of non-newtonian flow in annuli
Maia, M.C.A.;Gasparetto, C.A.;
Brazilian Journal of Chemical Engineering , 2003, DOI: 10.1590/S0104-66322003000200014
Abstract: continuity and momentum equations applied to the entrance region of an axial, incompressible, isothermal, laminar and steady flow of a power-law fluid in a concentric annulus, were solved by a finite difference implicit method. the newtonian case was solved used for validation of the method and then compared to reported results. for the non-newtonian case a pseudoplastic power-law model was assumed and the equations were transformed to obtain a pseudo-newtonian system which enabled its solution using the same technique as that used for the newtonian case. comparison of the results for entrance length and pressure drop with those available in the literature showed a qualitative similarity, but significant quantitative differences. this can be attributed to the differences in entrance geometries and the definition of asymptotic entrance length.
A numerical solution for the entrance region of non-newtonian flow in annuli
Maia M.C.A.,Gasparetto C.A.
Brazilian Journal of Chemical Engineering , 2003,
Abstract: Continuity and momentum equations applied to the entrance region of an axial, incompressible, isothermal, laminar and steady flow of a power-law fluid in a concentric annulus, were solved by a finite difference implicit method. The Newtonian case was solved used for validation of the method and then compared to reported results. For the non-Newtonian case a pseudoplastic power-law model was assumed and the equations were transformed to obtain a pseudo-Newtonian system which enabled its solution using the same technique as that used for the Newtonian case. Comparison of the results for entrance length and pressure drop with those available in the literature showed a qualitative similarity, but significant quantitative differences. This can be attributed to the differences in entrance geometries and the definition of asymptotic entrance length.
Reologia do suco de acerola: efeitos da concentra??o e temperatura
Silva, F.C. da;Guimar?es, Daniela Helena Pelegrine;Gasparetto, C.A.;
Ciência e Tecnologia de Alimentos , 2005, DOI: 10.1590/S0101-20612005000100020
Abstract: the rheological behavior of the industrialized acerola juice was studied at different soluble solids concentrations 4, 7, 10, 13 and 16obrix and temperatures from 5 to 85oc, using a concentric cylinder rheometer. rheograms were fitted according to the following models: ostwald-de waele or power law, herschel-bulkley, mizrahi & berk and casson. the best results were obtained using the herschel-bulkley model and the low values presented by the behavior index (0,338 < nhb < 0,759) confirm the pseudoplastic behavior of the acerola juice. an equation similar to the arrhenius one (ha = h0 exp(eat/rt)) described the effect of the temperature on the acerola juice. the results also showed that the activation energy decreases with the increasing in juice concentration, varying from 3.50kcal/gmol (4obrix) to 1.79kcal/gmol (16obrix). potential and exponential models were tested considering the apparent viscosity data as a function of the soluble solids concentrations. for this purpose, the potential model showed the best performance.
Comportamento reológico da polpa de manga (Mangífera indica L) - efeito dos sólidos insolúveis
VIDAL, J.R.M.B.;GASPARETTO, C.A.;
Ciência e Tecnologia de Alimentos , 2000, DOI: 10.1590/S0101-20612000000200008
Abstract: mango juice reological study had been evaluated - the effect of unsolvable solids through sifting with different meshes and in the centrifuged juice. the results were analysed according to casson and mizrahi - berk reological models. three quite different set were identified by the product passed through the (a) "finisher" 1,6mm and sieve of 1,8mm, (b) sieve of 0,84mm and 0,59mm and (c) sieve of 0,149mm and centrifuged material.
Comportamento reológico da polpa de manga (Mangífera indica L) - efeito dos sólidos insolúveis
VIDAL J.R.M.B.,GASPARETTO C.A.
Ciência e Tecnologia de Alimentos , 2000,
Abstract: Foi avaliado o estudo reológico do suco de manga - efeito dos sólidos insolúveis a peneiramento com diferentes malhas e no suco centrifugado. Os resultados foram analisados em fun o do ajuste dos modelos reológicos de Casson e de Mizrahi-Berk. Três conjuntos bem diferenciados foram identificados pelo produto passado em (a) `finisher' de 1,6mm e peneira de 1,8mm; (b) peneira de 0,84mm e 0,59mm e (c) peneira de 0,149mm e material centrifugado.
Models of the electroreduction of passive layers on cobalt
Gervasi, C.A.;
Journal of the Brazilian Chemical Society , 1997, DOI: 10.1590/S0103-50531997000200015
Abstract: potentiostatic current transient techniques were employed to study the electroreduction process of surface layers formed on polycrystalline cobalt in carbonate-bicarbonate ion-containing solutions. the dynamic system analysis performed using parametric identification procedures and non-linear fit routines demonstrated that data obtained under a wide variety of experimental conditions may be interpreted by taking into account the participation of various co(ii)/co(iii)-containing surface species. the influence of the anodizing time at the potential of oxide film formation may be discussed on the basis of the proposed electroreduction models.
Insights into the role of hydration in protein structure and stability obtained through hydrostatic pressure studies
Royer, C.A.;
Brazilian Journal of Medical and Biological Research , 2005, DOI: 10.1590/S0100-879X2005000800003
Abstract: a thorough understanding of protein structure and stability requires that we elucidate the molecular basis for the effects of both temperature and pressure on protein conformational transitions. while temperature effects are relatively well understood and the change in heat capacity upon unfolding has been reasonably well parameterized, the state of understanding of pressure effects is much less advanced. ultimately, a quantitative parameterization of the volume changes (at the basis of pressure effects) accompanying protein conformational transitions will be required. the present report introduces a qualitative hypothesis based on available model compound data for the molecular basis of volume change upon protein unfolding and its dependence on temperature.
JAK/STAT-deficient cell lines
Bonjardim, C.A.;
Brazilian Journal of Medical and Biological Research , 1998, DOI: 10.1590/S0100-879X1998001100004
Abstract: mutant cell lines b3 and b10, which are unresponsive to both interferon (ifn)-a and ifn-g, and line b9, which does not respond to ifn-g stimulation, are described. the mutants were submitted to fluorescence-activated cell sorting (facs) from a cellular pool, which was obtained from the parental cell line 2c4 after several rounds of mutagenesis. the unresponsiveness to ifn stimulation was observed both in terms of expression of cell surface markers (cd2, class i and ii hlas) and mrna expression of ifn-stimulated genes (2'-5' oligoadenylate synthetase (oas), 9-27, and guanylate binding protein (gbp)). genetic crossing of b3, b9 and b10 with u3 (stat1-), g2a (jak2-) and u4 (jak1-) mutants, respectively, did not restore ifn responsiveness to the hybrid cell lines. however, when these cell lines were crossed with the same mutants, but using the pairwise crosses b3 x u4, b9 x u3 and b10 x u3, the cell hybrids recovered full ifn responsiveness. the present genetic experiments permitted us to assign the mutant cell lines b3, b9 and b10 to the u3, g2 and u4 complementation groups, respectively. these conclusions were supported by the analysis of ifn-stimulated genes in the mutants.
DIESEL CHARACTERIZATION BY HIGH RESOLUTION MASS SPECTROMETRY-GAS CHROMATOGRAPHY
BALDRICHF,C.A;
CT&F - Ciencia, Tecnología y Futuro , 1998,
Abstract: high-resolution mass spectrometry-gas chromatography is combined with the hc22 method in order to obtain a detailed information about the chemical composition of diesel and the distribution of different compound types in terms of its final boiling temperature from a single analysis. the total time elapsed from sample injection and signal processing to obtain final results is 90 minutes. this fact makes this methodology a new and very important tool for the decision making process concerning the most suitable final boiling temperature and the type of treatment of the product in order to obtain diesel that fulfills the international standards. the consistency and repeatability of the experimental results are demonstrated.
Temperature effect on CARBON biomass in soils FROM TROPICAL AND TEMPERATE REGIONS
Vasconcellos, C.A.;
Scientia Agricola , 1998, DOI: 10.1590/S0103-90161998000100016
Abstract: four soils from various origins, (tropical and temperate regions) were amended with 14c labelled glucose (1mg c.g-1 soil) and incubated at 15oc and 35oc to determine the temperature effect on the carbon turnover and on the microbial biomass. the temperature effect on the biomass increased with the glucose addition. the biomass mineralization rates were higher at 35oc than at 15oc and higher for woburn and pegwell soils (temperate region) than for capinopolis and janauba (tropical region). specific respiration rate (srr) of new biomass (from glucose) and old biomass showed different behaviors between soils. at 15oc, the turnover c was 207, 225, 115 and 141 days for janauba, capinopolis, woburn and pegwell soil, respectively. at 35oc, it was 92, 69, 69 and 33 days for the same soils. the residual 14c in the soil was higher at 35oc. the final total biomasses at 15oc and 35oc were correlated with the initial soil carbon content. there was an average of 31 and 8 mg of biomass c.g-1 soil organic carbon, respectively at 15oc and 35oc. the initial carbon content was an important factor to explain the mineralization rate at 35oc.
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