Avaliação do sistema de monitoramento computadorizado de digestão in vitro: 1. Testes preliminares

O objetivo deste trabalho foi testar o sistema de monitoramento computadorizado da produção de gás in vitro. Essa técnica facilita estudos da degradação das frações solúveis e insolúveis das forragens, quantificadas pela produção de gás (CO2 e CH4) oriunda do metabolismo microbiano e medida por sensor de pressão. Diversas quantidades de amostras (50 a 110 mg de feno de alfafa) e outros alimentos foram testadas. Também, a influência da quantidade de líquido ruminal (2,0 ou 3,0 mL), com ou sem barras magnéticas agitadoras nos frascos incubatórios, na digestibilidade de 100 mg de feno de alfafa, foi estudada. A quantidade de 100 mg de amostra, 2,0 mL de líquido ruminal e sem barra magnética agitadora, proporcionou os menores coeficientes de variação na produção de gás. em conclusão, 2,0 mL de líquido ruminal, sem barra e com 100 mg de amostra, apresentaram maior precisão na curva de digestão.

Comparação do sistema de monitoramento computadorizado de digestão in vitro com os métodos in vivo e in situ: 2. Uso do resíduo da matéria seca de forragens

RESUMO - O objetivo deste trabalho foi comparar o sistema de monitoramento computadorizado da produção de gás in vitro com os métodos in vivo e in situ. Nas comparações, foram utilizadas silagens de milho com alto/baixo teores de matéria seca, com/sem inoculante. A digestibilidade das silagens com alto teor de matéria seca (MS), com/sem inoculação, não apresentou diferenças entre os métodos analisados. Quando avaliadas separadamente do efeito do inóculo, essas silagens diferiram nos métodos in vitro/gás e in situ, mas não no in vivo. Entretanto, quando analisadas somente sob efeito do inoculante, apenas no método in situ houve diferença. Não foram encontradas diferenças na digestibilidade da fibra em detergente neutro (FDN) das silagens com alta ou baixa MS, inoculadas ou não, bem como em relação ao pH ao final da digestão. em conclusão, o desaparecimento da MS e FDN quantificada pelo resíduo no sistema in vitro/gás foi semelhante aos demais métodos avaliados.

Avaliação do sistema de monitoramento computadorizado de digestão in vitro: 3. Desaparecimento da matéria seca e/ou FDN pela produção de gás

RESUMO - Os objetivos deste trabalho foram avaliar o sistema de monitoramento computadorizado da produção de gás in vitro e compará-lo com os métodos in vivo e in situ. Nos métodos de digestibilidade (MS), foram utilizadas amostras de silagens de milho com alto/baixo teor de MS, com/sem inoculante. Avaliando a digestibilidade das silagens, pelo gás produzido na fermentação, os resultados da extensão da degradação (A+D) foram: 21,5; 22,6; 22,1; e 20,9 mL de gás/100 mg MS, sem diferença significativa. Os coeficientes de determinação obtidos na produção de gás total, em relação ao potencial de degradação obtido in situ, mostraram-se elevados para silagem de milho com alta MS inoculada (R²= 0,99), alta MS não-inoculada (R²= 0,98), baixa MS inoculada (R²= 0,94) e baixa MS não-inoculada (R²=0,93). O desaparecimento da MS e/ou fibra em detergente neutro (FDN), quantificada pelo gás produzido no sistema in vitro/gás, apresentou resultados semelhantes aos demais métodos avaliados.

UNUSUALLY STRONG ATTRACTION IN THE PRESENCE OF CONTINUUM BOUND-STATE

The result of few-particle ground-state calculation employing a two-particle nonlocal potential supporting a continuum bound state in addition to a negative-energy bound state has occasionally revealed unusually strong attraction in producing a very strongly bound ground state. In the presence of the continuum bound state the difference of phase shift between zero and infinite energies has an extra jump of pi as in the presence of an additional bound state. The wave function of the continuum bound state is identical with that of a strongly bound negative-energy state, which leads us to postulate a pseudo bound state in the two-particle system in order to explain the unexpected attraction. The role of the Pauli forbidden states is expected to be similar to these pseudo states.

Polycyclic aromatic hydrocarbons from wood pyrolyis in charcoal production furnaces

Polycyclic aromatic hydrocarbons (PAH) were measured in smoke samples from wood carbonization during charcoal production, in both particulate matter (PM) and gaseous phases. Samples were acquired using a medium-volume air sampler at 1.5 m distance from the furnace. Particle-bound PAH were collected on Fluoropore polytetrafluoroethylene filters and gas-phase PAH were collected into sorbent tubes with XAD-2 resin. PAH were extracted with dichloromethane-methanol and analyzed using gas chromatography-mass spectrometry. The results showed total emission from the furnace of 26 mu g/m(3) for the 16 PAH and 2.8 mu g/m(3) for the 10 genotoxic PAH (from fluoranthene to benzo[g,h,i]perylene). High emission of 16 PAH in the first 8 h of wood carbonization was detected (64 mu g/m(3); 56% of the total emission). Associated with PM, 11% of the total emission of 16 PAH (in both phases) and 60% of 10 genotoxic PAH were found. Relative ratios (for example, [Phe]/[Phe] + [Ant]) for the PAH of the same molecular weight were obtained and compared with the published data. The concentrations of benzo[a]pyrene equivalent (BaPeq) were estimated using the list of toxic equivalent factors suggested by Nisbet and LaGoy, 1992. The values of 0.30 and 0.06 mg/m3 were obtained for the total concentrations of BaPeq in PM and gaseous phase, respectively. (c) 2006 Elsevier B.V. All rights reserved.

RESULTS FROM THE SLD BARREL CRID DETECTOR

We report on operational experience with an experimental performance of the SLD barrel Cherenkov Ring Imaging Detector from the 1992 and 1993 physics runs. The liquid (C6F14) and gas (C5F12) radiator recirculation systems have performed well, and the drift gas supply system has operated successfully with TMAE for three years. Cherenkov rings have been observed from both the liquid and gas radiators. The number and angular resolution of Cherenkov photons have been measured, and found to be close to design specifications.

Construction and performance of a drop cell for the nephelometric determination of sulfur dioxide

A nephelometric technique based on a liquid drop is described for the measurement of atmospheric sulfur dioxide. A 40-mul drop of barium chloride and hydrogen peroxide solution is suspended in a flowing-air sampling stream. The sulfur (IV) collected is oxidized to sulfur (VI) and finally precipitated as barium sulfate. Nephelometric detection of drop is achieved by an appropriate arrangement consisting of an optical fiber contacting the drop and a photodiode placed at 90degrees relative to the fiber. The design and characteristics of this drop-based gas sensor system are described. The analytical response, as photocurrent, is proportional to the product of the sampling period and the sulfur dioxide concentration. The detection limit is ca. 1.1 mg m(-3) for a 10-min sampling time. The present technique is fairly rapid and simple, uses a small amount of reagent and is set up with low-cost equipment, making this system economically viable. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Cogasification of solid fuels

High efficiency gas turbine based systems, utility deregulation and more stringent environmental regulations strongly favor the use of natural gas over coal and other solid fuels in new electricity generators. Solid fuels could continue to compete, however, if a low cost gasifier fed by low cost feedstocks can be coupled with a gas turbine system. We examine on-site gasification of coal with other domestic fuels in an indirectly heated gasifier as a strategy to lower the costs of solid fuel systems. The systematics of gaseous pyrolysis yields assembled with the help of thermal measurement data and molecular models suggests blending carbonaceous fuels such as coal, coke or char with oxygenated fuels such as biomass, RDF, MSW, or dried sewage sludge. Such solid fuel blending can, with the help of inexpensive catalysts, achieve an optimum balance of volatiles, heating values and residual char thus reducing the technical demands upon the gasifier. Such simplifications should lower capital and operating costs of the gasifier to the mutual benefit of both solid fuel communities.

The stability evolution of a family of simply periodic lunar orbits

The present work deals with a family of simply periodic orbits around the Moon in the rotating Earth Moon-particle system. Taking the framework of the planar, circular, restricted three-body problem, we follow the evolution of this family of periodic orbits using the numerical technique of Poincaré surface of section. The maximum amplitude of oscillation about the periodic orbits are determined and can be used as a parameter to measure the degree of stability in the phase space for such orbits. Despite the fact that the whole family of periodic orbits remain stable, there is a dichotomy in the quasi-periodic ones at the Jacobi constant Cj = 2.85. The quasi-periodic orbits with Cj < 2.85 oscillate around the periodic orbits in a different way from those with Cj > 2.85. © 1999 Elsevier Science Ltd. All rights reserved.

Time analysis for temporary gravitational capture: Satellites of Uranus

We study the problem of gravitational capture in the framework of the Sun-Uranus-particle system. Part of the space of initial conditions is systematically explored, and the duration of temporary gravitational capture is measured. The location and size of different capture-time regions are given in terms of diagrams of initial semimajor axis versus eccentricity. The other initial orbital elements - inclination (i), longitude of the node (Ω), argument of pericenter (ω), and time of pericenter passage (τ) - are first taken to be zero. Then we investigate the cases with ω = 90°, 180°, and 270°. We also present a sample of results for Ω = 90°, considering the cases i = 60°, 120°, 150°, and 180°. Special attention is given to the influence of the initial orbital inclination, taking orbits initially in opposition at pericenter. In this case, the initial inclination is varied from 0° to 180° in steps of 10°. The success of the final stage of the capture problem, which involves the transformation of temporary captures into permanent ones, is highly dependent on the initial conditions associated with the longest capture times. The largest regions of the initial-conditions space with the longest capture times occur at inclinations of 60°-70° and 160°. The regions of possible stability as a function of initial inclination are also delimited. These regions include not only a known set of retrograde orbits, but also a new sort of prograde orbit with inclinations greater than zero.

Study of a hybrid solid oxide fuel cell: Energetic analysis and sankey diagram

In this paper a hybrid solid oxide fuel cell (SOFC) system is analyzed. This system applies a combined cycle utilizing gas turbine associated to a SOFC for rational decentralized energy production. Initially the relative concepts about the fuel cell are presented, followed by some chemical and technical informations such as the change of Gibbs free energy in isothermal fuel oxidation (or combustion) directly into electricity. This represents a very high fraction of the lower heating value (LHV) of a hydrocarbon fuel. In the next step a methodology for the study of SOFC associated with a gas turbine system is developed, considering the electricity and steam production for a hospital, as regard to the Brazilian conditions. This methodology is applied to energetic analysis. Natural gas is considered as a fuel. In conclusion, it is shown by a Sankey Diagram that the hybrid SOFC system may be an excellent opportunity to strengthen the decentralized energy production in Brazil. It is necessary to consider that the cogeneration in this version also is a sensible alternative from the technical point of view, demanding special methods of design, equipment selection and mainly of the contractual deals associated to electricity and fuel supply.

Uso de filtro de mangas para tratamento de gases resultantes da combustão de bagaço de cana

Pós-graduação em Engenharia Mecânica - FEB

Clostridium perfringens e Salmonella spp em camas de frango, novas e reutilizadas, e seus efeitos sobre o desempenho zootécnico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Código computacional para análise de sistemas de cogeração com turbinas a gás

Pós-graduação em Engenharia Mecânica - FEG

Real-time monitoring of ozone in air using substrate-integrated hollow waveguide mid-infrared sensors

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)