Navegando por Data de Publicação, começando com "2009-03-09"

Filtrar resultados por ano ou mês

Agora exibindo 1 - 5 de 5

Eletrodissolução de alumínio em polpa celulósica proveniente da reciclagem de embalagens cartonadas multicamadas
(Universidade Federal de São Carlos, 2009-03-09) Neves, Fernando Luiz; Coury, José Renato; https://lattes.cnpq.br/7563266192997044
In this work we studied the aluminum electro-dissolution in cellulose pulp from milk and beverage cartons recycling. The objective for this research is to reduce the aluminum particles sizes to values below 300 μm. In the first stage, the process was studied in lab scale using an electrochemical reactor anode made of Titanium recovered with ruthenium oxide (DSA® Ti/Ti0.6Ru0.3O2- De Nora do Brasil) and cathode made of titanium without recovering. In this experiment in lab scale, the electro-dissolution of aluminum presented a first order kinetic reaching 88 to 92% of electrochemical efficiency after 500 minutes. From measurements of particles diameter by optical microscopy it was possible to calculate the total area occupied by the aluminum particles which was quantified by image efficiency. For the lab experiment the image efficiency reached values between 74 and 88%. This first study was conducted in three current density: 250, 320 and 700 A/m2 and during 60, 180, 480 and 960 minutes. After 60 minutes no particles above 300 μm was detected. In the second stage, a pilot electrochemical reactor was designed taking the lab reactor parameters and keeping the same material for anode and cathode. This system was evaluated for current densities of 22, 250 and 270 A/m2 during 120 and 420 minutes. The best result was observed with the application of 250 A/m2 during 420 minutes reaching electrochemical and image efficiency of 60 and 72% respectively. The mechanical resistance for the cellulose pulp was evaluated before and after the electrochemical treatment and it was noted that it affected the freeness in a positive way. Tear, tensile, burst, zero span tensile index and stretch, if compared to non-treated and refined pulp to the same freeness, presented effects positive or negative depending on the current density applied and the treatment time. However, all the measurements for mechanical properties after the electrochemical treatment are in the acceptable level for paper market. The energy consumption was evaluated for the lab and pilot experiment and optimized industrial conditions were simulated. Based on these simulations and on the experiments results, we can conclude that a plant that recycles 50 ton per day of milk and beverage cartons needs 655 kW of electric power to treat all the pulp extracted from these packages using the electrochemical process considering that paper represents 75% (w/w) of milk and beverage cartons composition.
Morfologia, conservação e ecofisiologia da germinação de sementes de Psidium cattleianum Sabine
(Universidade Federal de São Carlos, 2009-03-09) Silva, Antonio da; Perez, Sonia Cristina Juliano Gualtieri de Andrade; https://lattes.cnpq.br/9973185407856723
Psidium cattleianum has great potential for animal and human food, for multiple uses of wood and for recovery of degraded areas. Due to its economic importance and to the lack of information on seed germination and conservation, this study aimed to find the morphology of fruits, seeds, seedlings and young plants and to establish the presence or absence of dormancy. Furthermore, studies have been conducted relating to the conservation of seeds, the germination responses under different temperatures, qualities of light and humidity levels of the substrates. All these studies focus to generate knowledge that can help to support conservation projects, management and restoration of altered and/or protected areas. By the results, it was found that seeds and fruits showed had little biometric variation and the greatest variation occured in number of seeds per fruit. The seeds showed tegumentary dormancy, the germination is hypogeal and the seedlings are cryptocotylar. Seeds immersed in water at room temperature in laboratory, proved germination pending quicker 20- 30oC in white light. The seed immersed in sulfuric acid during ten, 20 and 25 minutes, subjected to temperatures of 20-30oC under white light, showed higher germination rate. The placing of the seeds in waterproof packed and stored in natural environment in the laboratory or in a dry chamber, as well as the seeds packed in semi-permeable package and stored in cold chamber, were suitable for the preservation during 1,107 days and this fact, associated with little variation on the moisture content allowed to classify them as orthodoxe ones. The test of electrical conductivity with scarified seeds in the sulfuric acid during 25 minutes was not efficient to evaluate its physiological quality. The highest values of seed germination and speed rate were obtained at the temperature of 20-30oC under white light. Regardless of temperatures, the seeds showed drastic reduction in speed and germination in absence and presence of far red light. The seeds are positive preferential photoblastic. It is assumed that seeds germination is better under light natural conditions. The highest values of seed speed and germination were obtained, under white light regardless of seed age. The highest seed speed and germination were obtained at 20-30oC, under white light in 15 mL of water, as well as 50 grams of sand moistened with six, nine and 12 mL of water.
Análise da secagem de pastas em leito de jorro
(Universidade Federal de São Carlos, 2009-03-09) Almeida, André Ricardo Felkl de; Freire, José Teixeira; https://lattes.cnpq.br/2270677706718167; https://lattes.cnpq.br/0168456777470325
The objective of this Doctoral Thesis was to analyse the fluidynamics and the heat and mass transfer of paste drying in a spouted bed under transient operation and to obtain detailed experimental data on the disturbed response of the system due to the presence of the liquid phase. This work also comprises the application of a CST model to predict temperature and moisture profiles in both the gas and solid phases. The paste-like matter employed in the experiments was distilled water, wastewater sludge, skim milk, homogenized whole egg and calcium carbonate. For each one of these pastes, experiments were done in two different spouted bed configurations (full and half column bed) operating with different feed rates, under inlet spout air flow rate at 15 and 30 % above the minimum spouting velocity and temperatures of 80 and 100 °C. In the full column spouted bed, measurements of inlet air flow rate variations, pressure drop, inlet air temperature, particle bed temperature at three axial positions in the annulus, outlet air temperature, dry and wet bulb temperatures at the cyclone exhaust and moisture content of powder and paste coat of inert particles were done. For the half column spouted bed, measurements of inlet air flow rate variations, pressure drop, inlet and outlet air temperature, dry and wet bulb temperatures at the cyclone exhaust, particles velocities in the annulus, spout and fountain, spout channel shape and dimensions and fountain high were done. The results obtained showed that the transient operation analysis was adequate and encouraging as a means to obtain further information on the drying process in spouted bed. Among the main results of this work is the important finding that the time required for the spouted bed to reach steady state may largely vary depending on the feed flow rate and spouting characteristics. The fluidynamics analysis showed that spouting characteristics may significantly change, indicating system instability, depending on the type of paste and the concentration and flow rate of the feed. As far as the CST model is concerned, it was seen that experimental data and predicted values were in good agreement, although the drying kinetic equation was highly dependent on paste concentration and density.
Interação multualista entre morcegos nectarívoros(Chiroptera) e a pata-de-vaca Bauhinia Holophylla Steud. (Fabaceae) em uma área de cerrado: atração e recompensa
(Universidade Federal de São Carlos, 2009-03-09) Estêvão, Julia Ramos; Matos, Dalva Maria da Silva; https://lattes.cnpq.br/4728734263109138; https://lattes.cnpq.br/2869410150047234
(Attraction and reward of nectar-feeding bats (Chiroptera: Phyllostomidae) by the plant Bauhinia holophylla (Fabaceae) in a Brazilian savanna) In facultative mutualisms, species compete strongly with each other for partners. It is expected that sympatric plant species pollinated by the same guild of animals invest heavily in attracting partners. Thus, we investigated interactions between Bauhinia holophylla and bats to test whether: (1) this plant is visited mostly by bats and if it assures attraction of bats through typically chiropterophilic floral traits; and (2) bats adjust their foraging behavior to the temporal pattern of nectar production by flowers. We worked in a Cerrado area in southeastern Brazil, recording floral visitors and their foraging pattern. We determined nectar production and how its concentration varied throughout the night. Three species of bats were the main legitimate visitors. Bauhinia holophylla floral characteristics followed predictions of the chiropterophyly syndrome: brush format, white color, sweet odor, crepuscular anthesis, nocturnal nectar production and flowers exposed on branches. Bats visited flowers more often at dusk, there were differences in the main hours of overflight, reconnaissance flight and visitation. Solute concentration in nectar was always highest at the beginning of the night and fell gradually thereafter. Bats did not visit more flowers when nectar concentration was higher. We conclude that in this interaction dependence is asymmetric, following patters of other facultative mutualisms, because Bauhinia holophylla depends on bats for its pollination, but bats presumably do not depend on it for food.
Guildas de Tetraodontiformes (Teleostei, Acanthopterygii) em um complexo estuarino tropical
(Universidade Federal de São Carlos, 2009-03-09) Andrade, Amanda Carvalho de; Verani, José Roberto; https://lattes.cnpq.br/0053232138684810; https://lattes.cnpq.br/7833843926071032
The demersal ichthyofauna of Guanabara bay was sampled bimonthly, during two years, in ten stations distributed along a hydrobiological gradient. An otter trawl was employed, conducting 30 minute trawls, at a speed of 2 knots, summing up to 240 hours of fishing effort from July 2005 to June 2007. A total of 16,081 Tetraodontiformes specimens were collected, representing ten species divided among the families Ostraciidae, Monacanthidae, Tetraodontidae and Diodontidae. The otter trawl was considered an adequate technique to sample the group, although it may underestimate the abundances of species associated with hard bottoms (Acanthostracion sp.) and marginal areas (Sphoeroides spp.). Tetraodontiformes fishes appear to be well adapted to hydrological variations and to inhospitable conditions prompted by intense eutrophication. However, abiotic factors traditionally considered important in the structuring of estuarine communities play a secondary role in regulating the distribution of Tetraodontiformes. The type of sediment appears as the most important physical factor, but acts only as an indicator of ecological domain. The low explicability of physical-chemical variables, in addition to the relative stability of the bay s ichthyofauna, suggests the influence of biological parameters. The main biological factors related with the ichthyocenosis seasonal variations are food items availability, intra- and interspecific competition and the species reproductive cycles. Tetraodontiformes exhibited a wide variation of uses in Guanabara bay, utilizing it as a resting, feeding and growing area. However, it was not possible to establish a relation of dependence upon the estuary for any of the species, because the same population strata occur the in coastal regions of South-Southeastern Brazil. Among the ten species of Tetraodontiformes captured, eight were categorized as marine estuarine opportunists and two as marine stragglers. Chilomycterus spinosus population boom indicated an ecological misbalance and must be carefully investigated. Subsequent studies should adopt a population approach of these species and attempt to elucidate the relationships between estuarine and marine stocks.