Sistema de secagem solar para frutos tropicais e modelagem da secagem de banana em um secador de coluna estática

In this study were projected, built and tested an electric solar dryer consisting of a solar collector, a drying chamber, an exhaust fan and a fan to promote forced hot air convection. Banana drying experiments were also carried out in a static column dryer to model the drying and to obtain parameters that can be used as a first approximation in the modeling of an electric solar dryer, depending on the similarity of the experimental conditions between the two drying systems. From the banana drying experiments conducted in the static column dryer, we obtained food weight data as a function of aqueous concentration and temperature. Simplified mathematical models of the banana drying were made, based on Fick s and Fourier s second equations, which were tested with the experimental data. We determined and/or modeled parameters such as banana moisture content, density, thin layer drying curves, equilibrium moisture content, molecular diffusivity of the water in banana DAB, external mass transfer coefficient kM, specific heat Cp, thermal conductivity k, latent heat of water evaporation in the food Lfood, time to heat food, and minimum energy and power required to heat the food and evaporate the water. When we considered the shrinkage of radius R of a banana, the calculated values of DAB and kM generally better represent the phenomenon of water diffusion in a solid. The latent heat of water evaporation in the food Lfood calculated by modeling is higher than the latent heat of pure water evaporation Lwater. The values calculated for DAB and KM that best represent the drying were obtained with the analytical model of the present paper. These values had good agreement with those assessed with a numeric model described in the literature, in which convective boundary condition and food shrinkage are considered. Using parameters such as Cp, DAB, k, kM and Lfood, one can elaborate the preliminary dryer project and calculate the economy using only solar energy rather than using solar energy along with electrical energy

Processos aleatórios não-markovianos: perfis de memória

One of the mechanisms responsible for the anomalous diffusion is the existence of long-range temporal correlations, for example, Fractional Brownian Motion and walk models according to Elephant memory and Alzheimer profiles, whereas in the latter two cases the walker can always "remember" of his first steps. The question to be elucidated, and the was the main motivation of our work, is if memory of the historic initial is condition for observation anomalous diffusion (in this case, superdiffusion). We give a conclusive answer, by studying a non-Markovian model in which the walkers memory of the past, at time t, is given by a Gaussian centered at time t=2 and standard deviation t which grows linearly as the walker ages. For large widths of we find that the model behaves similarly to the Elephant model; In the opposite limit (! 0), although the walker forget the early days, we observed similar results to the Alzheimer walk model, in particular the presence of amnestically induced persistence, characterized by certain log-periodic oscillations. We conclude that the memory of earlier times is not a necessary condition for the generating of superdiffusion nor the amnestically induced persistence and can appear even in profiles of memory that forgets the initial steps, like the Gausssian memory profile investigated here.

Freqüência de anticorpos anti-Neospora caninum em soros de caprinos do estado de São Paulo e sua relação com o manejo dos animais

Com o objetivo de se avaliar a freqüência de caprinos leiteiros soropositivos para Neospora caninum, no estado de São Paulo, e se verificarem possíveis associações com idade, sexo e problemas reprodutivos, nos capris, e, também, presença de cães, nas propriedades, foram obtidos soros de 923 caprinos de ambos os sexos e idade acima de 3 meses. Os animais eram provenientes de 17 propriedades de diferentes municípios. Para o diagnóstico, foi utilizado o teste de aglutinação para Neospora (NATe25), e, em todos os capris, aplicou-se um inquérito a partir do qual se obtiveram informações epidemiológicas e de esfera reprodutiva. Todos os resultados estatísticos foram discutidos no nível de 5% de significância. Assim, chegou-se à conclusão de que a freqüência percentual de positividade para N. caninum foi de 19,77%, e, em apenas uma propriedade, não houve registro de animal soropositivo, o que revela difusão do agente, no Estado. Não foram verificadas diferenças significativas entre freqüências de positividade quanto ao sexo, idade ou problemas reprodutivos. Porém, ressalta-se que a presença de cães, nos capris, foi associada a uma maior freqüência de caprinos soropositivos a N. caninum. A representação geográfica da distribuição de caprinos soropositivos para o protozoário, em mapa coroplético em hachuras, pode implicar em um ganho considerável para estudos da epidemiologia geográfica, na elaboração de um planejamento de controle da enfermidade.

Desgaste de ferramentas no torneamento com alta velocidade de corte da superliga waspaloy

Nesse trabalho, procurou-se estudar os mecanismos de desgaste de diversas geometrias de ferramentas cerâmicas (Al2O3 + SiCw e Al2O3 + TiC) e ferramentas de PCBN. Para isto foram realizados ensaios de torneamento com alta velocidade de corte em uma superliga à base de níquel (Waspaloy) com dureza de aproximadamente 40 HRC sob condição de corte a seco. As superligas são conhecidas como materiais de difícil usinabilidade devido à alta dureza, alta resistência mecânica em alta temperatura, afinidade para reagir com materiais da ferramenta e baixa condutividade térmica. Os resultados mostraram que o material da ferramenta e a geometria influenciaram o comportamento dos mecanismos de desgaste. de uma maneira geral, o tipo de desgaste dominante foi o de entalhe e os mecanismos foram abrasão, attrition (aderência com arrastamento) e provável difusão na maioria das ferramentas utilizadas.

Preparation and antimicrobial activity of gelatin microparticles containing propolis against oral pathogens

Gelatin microparticles containing propolis ethanolic extractive solution were prepared by spray-drying technique. Particle,, with regular morphology, mean diameter ranging of 2.27 mu m to 2.48 mu m, and good entrapment efficiency for propolis were obtained. The in vitro antimicrobial activity of microparticles was evaluated against microorganisms of oral importance (Enterococcus faecalis, Streptococcus salivarius, Streptococcus sanguinis, Streptococcus mitis, Streptococcus mutans, Streptococcus sobrinus, Candida albicans, and Lactobacillus casei). The utilized techniques were diffusion in agar and determination of minimum inhibitory concentration. The choice of the method to evaluate the antimicrobial activity of microparticles showed be very important. The microparticles displayed activity against all tested strains of similar way to the propolis, showing greater activity against the strains of E. salivarius, S. sanguinis, S. mitis, and C albicans.

Particle growth during calcination of polycation oxides synthesized by the polymeric precursors method

The particle-growth kinetics of sodium niobate and zirconium titanate powders that were processed by the polymeric precursors method were studied. The growth kinetics that were studied for the particle, in the final stage of crystallization, showed that the growth process occurs in two different stages. For temperatures <800°C, the particle-growth mechanism is associated with surface diffusion, with an activation energy in the range of 40-80 KJ/mol. For temprratures >800°C, particle growth is controlled by densification of the nanometric particle cluster and by a neck-size-controlled particle-growth mechanism. The results suggest that this behavior was typical of the synthesis method, because two different polycation oxides presented the same behavior.

Effect of atmosphere and dopants on sintering of SnO2

Tin oxide is an n-type semiconductor material with a high covalent behavior. Mass transport in this oxide depends on the surface state promoted by atmosphere or by the solid solution of a non-isovalent oxide doping The sintering and grain growth of this type of oxide powder is then controlled by atmosphere and by extrinsic oxygen vacancy formation. For pure SnO2 powder the surface state depends only on the interaction of atmosphere molecules with the SnO2 surface. Inert atmosphere like argon or helium promotes oxygen vacancy formation at the surface due to reduction of SnO2 to SnO at the surface and liberation of oxygen molecules forming oxygen vacancies. As consequence surface diffusion is enhanced leading to grain coarsening but no densification. Oxygen atmosphere inhibits the SnO2 reduction decreasing the surface oxygen vacancy concentration. Addition of dopants with lower valence at sintering temperature creates extrinsic charged oxygen vacancies that promote mass transport at grain boundary leading to densification and grain growth of this polycrystalline oxide.

Verificação da atividade antibacteriana de sabonete líquido contendo extrato glicólico de Dimorphandra mollis Benth.

Dimorphandra mollis Benth., Compositae, false barbatimão, has been used topically as a healing, astringent and antibacterial. In this study, antibacterial activity was verified on liquid soap containing glycolic extract of D. mollis (DGE) at different concentrations (8, 15 and 20%) and at different pH levels (6 and 8). Five soap formulations (F) were prepared: F1 - tryclosan (0.1%), F2 - DGE (8%), F3 - DGE (15%), F4 - DGE (20%) and F5 - without preservatives. Bark of D. mollis were dried in a circulating air oven and ground. The rude extracts were prepared by turbo extraction with ethanol. After screening, the extract were concentrated in rotating evaporator, lyophilized and resuspended in propileneglycol to obtain the glycolic extract. The antimicrobial activity was verified by diffusion in agar method, using cylinder in plate. Plates containing Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli were incubated at 37°C for 24 hours. After incubation, the results were analysed with a pachymeter, observing the bacterial grouth inhibition halo diameter. It was verified that the liquid soap containing tryclosan caused on inhibition of bacterial growth at both pH levels; the soaps without preservatives and containing DGE, independently of the concentration and pH levels used, did not present antibacterial activity.

Antibacterial activity of gels with pomegranate, apricot and green tea glycolic extracts

Pomegranate (PGE) and green tea (GTGE) glycolic extracts are being employed in formulations because of their antiseptic and astringent effects. Apricot (AGE) glycolic extract possesses function cooling and antibacterial. The aim was to verify the antibacterial activity of these extracts incorporated in gel base. The antibacterial activity was verified by diffusion in agar method, using cylinder in plate. Plates containing Staphylococcus aureus (ATCC 6538p), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 10536) and Salmonella sp. (ATCC 19196) were incubated at 37°C for 24 hours. After incubation, the results were analysed with a pachymeter, observing the bacterial growth inhibition halo diameter and the statistical significance level was determined. PGE presented activity only against P. aeruginosa; GTGE presented activity against S. aureus, P. aeruginosa and E. coli; and AGE presented activity against P. aeruginosa and Salmonella sp. According to the experimental conditions, it is possible to conclude that GTGE presented the greater growth inhibition halo diameter when compared with other extracts, suggesting higher antibacterial action of this extract.

An analysis of the Hygiea asteroid family orbital region

(10) Hygiea is the fourth largest asteroid of the main belt, by volume and mass, and it is the largest member of its family, that is made mostly by low-albedo, C-type asteroids, typical of the outer main belt. Like many other large families, it is associated with a 'halo' of objects, that extends far beyond the boundary of the core family, as detected by traditional hierarchical clustering methods (HCM) in proper element domains. Numerical simulations of the orbital evolution of family members may help in estimating the family and halo family age, and the original ejection velocity field. But, in order to minimize the errors associated with including too many interlopers, it is important to have good estimates of family membership that include available data on local asteroid taxonomy, geometrical albedo and local dynamics. For this purpose, we obtained synthetic proper elements and frequencies of asteroids in the Hygiea orbital region, with their errors. We revised the current knowledge on asteroid taxonomy, including Sloan Digital Sky Survey-Moving Object Catalog 4th release (SDSS-MOC 4) data, and geometric albedo data from Wide-field Infrared Survey Explorer (WISE) and Near-Earth Object WISE (NEOWISE). We identified asteroid family members using HCM in the domain of proper elements (a, e, sin (i)) and in the domains of proper frequencies most appropriate to study diffusion in the local web of secular resonances, and eliminated possible interlopers based on taxonomic and geometrical albedo considerations. To identify the family halo, we devised a new hierarchical clustering method in an extended domain that includes proper elements, principal components PC1, PC2 obtained based on SDSS photometric data and, for the first time, WISE and NEOWISE geometric albedo. Data on asteroid size distribution, light curves and rotations were also revised for the Hygiea family. The Hygiea family is the largest group in its region, with two smaller families in proper element domain and 18 families in various frequencies domains identified in this work for the first time. Frequency groups tend to extend vertically in the (a, sin (i)) plane and cross not only the Hygiea family but also the near C-type families of Themis and Veritas, causing a mixture of objects all of relatively low albedo in the Hygiea family area. A few high-albedo asteroids, most likely associated with the Eos family, are also present in the region. Finally, the new multidomains hierarchical clustering method allowed us to obtain a good and robust estimate of the membership of the Hygiea family halo, quite separated from other asteroids families halo in the region, and with a very limited (about 3 per cent) presence of likely interlopers. © 2013 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society.

Degradation analysis of the SnO2 and ZnO-based varistors using electrostatic force microscopy

The degradation phenomena of ZnO and SnO2-based varistors were investigated for two different degradation methods: DC voltage at increased temperature and degradation with 8/20 μs pulsed currents (lightning type). Electrostatic force microscopy (EFM) was used to analyze the surface charge accumulated at grain-boundary regions before and after degradation. Before the degradation process, 85% of the barriers are active in the SnO2 system, while the ZnO system presents only 30% effective barriers. Both systems showed changes in the electrical behavior when degraded with pulses. In the case of the ZnO system, the behavior after pulse degradation was essentially ohmic due to the destruction of barriers (about 99% of the interfaces are conductive). After the degradation with 8/20 μs pulsed currents, the SnO2 system still presents nonohmic behavior with a significant decrease in the quantity of effective barriers (from 85% to 5%). However, when the degradation is accomplished with continuous current, the SnO2 system exhibits minimum variation, while the ZnO system degrades from 30% to 5%. This result indicates the existence of metastable defects of low concentration and/or low diffusion in the SnO2 system. High energy is necessary to degrade the barriers due to defect annihilation in the SnO2 system. © 2013 The American Ceramic Society.

Degradation of dipyrone via advanced oxidation processes using a cerium nanostructured electrocatalyst material

This work studied the degradation of dipyrone, via electrochemical processes and via electro-Fenton reaction using a 4% CeO2/C gas diffusion electrode (GDE) prepared via modified polymeric precursor method. This material was used to electrochemically generate H2O2 through oxygen reduction. The mean crystallite sizes estimated by the Scherrer equation for 4% CeO2/C were 4 nm for CeO2-x (0 4 4) and 5 nm for CeO2 (1 1 1) while using transmission electron microscopy (TEM) the mean nanoparticle size was 5.4 nm. X-ray photoelectron spectroscopy (XPS) measurements revealed nearly equal concentrations of Ce(III) and Ce(IV) species on carbon, which contained high oxygenated acid species like CO and OCO. Electrochemical degradation using Vulcan XC 72R carbon showed that the dipyrone was not removed during the two hour electrolysis in all applied potentials by electro-degradation. Besides, when the Fenton process was employed the degradation was much similar when using cerium catalysts but the mineralization reaches just to 50% at -1.1 V. However, using the CeO2/C GDE, in 20 min all of the dipyrone was degraded with 26% mineralization at -1.3 V and when the Fenton process was employed, all of the dipyrone was removed after 5 min with 57% mineralization at -1.1 V. Relative to Vulcan XC72R, ceria acts as an oxygen buffer leading to an increase in the local oxygen concentration, facilitating H2O2 formation and consequently improving the dipyrone degradation © 2013 Elsevier B.V. All rights reserved.

Design of biogas pipeline - Energy and sanitation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Caracterização genotípica microrganismos isolados de infecções da corrente sanguína relacionadas a cateteres em recém-nascidos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Síntese de sucroésteres derivados de ácidos piridínicos (ácido nicotínico, isonicotínico e pícolínico) e avaliação de suas atividades antimicrobianas

Pós-graduação em Engenharia e Ciência de Alimentos - IBILCE