Dispersion de Radiacion y Transferencia de Calor en Espumas Plasticas: Conductividades Termicas a Partir de Espectros Infrarrojos = Radiation Scattering and Heat Transfer in Cellular Plastics: Thermal Conductivities from Infrared Spectra

The mechanism of radiative heat flow in cellular materials is analyzed in terms of their spectral properties in the infrared region. Specifically, it was found that commercial polystyrene foams having average cell diameters of 100-150 μm behave as optically dense scattering media up to about 8 μm. At longer wavelengths, i.e. in the region where black bodies display their maximum emissive power at ambient temperatures, the scattering coefficient a markedly decreases and the material becomes almost transparent above 50 μm. The behavior of σ in this critical region does not follow a simple λ^(-n) law, revealing that the process should be classified as Mie scattering. It is shown that from this information, encoded as an effective scattering coefficient, overall thermal conductivities can be actually derived by means of standard techniques dealing with energy transfer in scattering media. The physical basis for relating cellular structure and net heat flow in plastic foams is thereby established

Heterogeneous decomposition of trichlorofluoromethane on carbonaceous surfaces

The interaction of trichlorofluoromethane with activated charcoal has been investigated by dynamic mass spectrometry up to 750 K. Prior physical adsorption, revealed in programmed desorption experiments, is followed by irreversible first-order decay with formation of nearly equimolar amounts of HCl above 550 K. This unexpectedly fast process has an apparent activation energy of only 59.4 kJ mol^(–1) and is demonstrably catalytic. The mechanism of Cl_3CF decomposition on carbon surfaces and its possible impact on atmospheric chemistry are discussed

Scattering hypervolume for ultracold bosons from weak to strong interactions

The elastic scattering properties of three bosons at low energy enter the many-body description of ultracold Bose gases via the three-body scattering hypervolume $D$. We study this quantity for identical bosons that interact via a pairwise finite-range potential. Our calculations cover the regime from strongly repulsive potentials towards attractive potentials supporting multiple two-body bound states and are consistent with the few existing predictions for $D$. We present the first numerical confirmation of the universal predictions for $D$ in the strongly interacting regime, where Efimov physics dominates, for a local nonzero-range potential. Our findings highlight how $D$ is influenced by three-body quasibound states with strong $d$-wave or $g$-wave characteristics in the weakly interacting regime.Comment: 13 pages, 8 figure

Very low pressure pyrolysis of phenylacetic acid

A Kinetic study of the very low pressure thermolysis of phenylacetic acid above 900 K reveals that its decomposition occurs in a concerted manner, yielding toluene and carbon dioxide, probably via a four-centre transition state [reaction (1)] [graphic omitted] with log[k_∞(1)/s^(–1)]=[(13 ± 0.3)–(12 200 ± 500)]/T

Isotopic fractionation of carbonyl sulfide in the atmosphere: Implications for the source of background stratospheric sulfate aerosol

In order to assess the contribution of carbonyl sulfide to stratospheric sulfate aerosol (SSA), we examined the stratospheric OC^(34)S and OC^(32)S concentration profiles in the infrared limb-transmittance spectra acquired by the JPL MkIV instrument. We found that OC^(34)S is preferentially depleted by solar photolysis. The derived ^(34)S enrichment factor: ε = +73.8 ± 8.6‰, in conjunction with literature values of δ^(34)S ∼ +11‰ for tropospheric OCS, and a ∼ 10% net processing of the OCS transported upwardly into the stratosphere, suggests that aerosol sulfate proceeding from OCS should be highly enriched in δ^(34)S ∼ 80‰, comparing our prediction with previous reports of δ^(34)S ∼ +2.6‰ for background SSA, we infer either that OCS is a minor contributor to SSA or that current views about its ^(34)S-abundance and atmospheric circulation are seriously flawed

Produção de suínos em sistema de ciclo completo: custos e receitas da utilização dos dejetos.

Este trabalho teve como objetivo estimar os custos de distribuição dos dejetos de uma criação de suínos com 42 matrizes em sistema de ciclo completo e as receitas obtidas do seu uso como substituto dos fertilizante químicos. Foram definidas as quantidades de dejetos produzidas, a área de aplicação e os custos de transporte. Posteriormente estimadas as receitas que os dejetos gerariam substituindo fertilizantes químicos como a uréia, o super triplo e o cloreto de potássio.bitstream/item/111047/1/Cot474.pd

Unmatched ventilation and perfusion measured by electrical impedance tomography predicts the outcome of ARDS

Background In acute respiratory distress syndrome (ARDS), non-ventilated perfused regions coexist with non-perfused ventilated regions within lungs. The number of unmatched regions might reflect ARDS severity and affect the risk of ventilation-induced lung injury. Despite pathophysiological relevance, unmatched ventilation and perfusion are not routinely assessed at the bedside. The aims of this study were to quantify unmatched ventilation and perfusion at the bedside by electrical impedance tomography (EIT) investigating their association with mortality in patients with ARDS and to explore the effects of positive end-expiratory pressure (PEEP) on unmatched ventilation and perfusion in subgroups of patients with different ARDS severity based on PaO2/FiO2 and compliance. Methods Prospective observational study in 50 patients with mild (36%), moderate (46%), and severe (18%) ARDS under clinical ventilation settings. EIT was applied to measure the regional distribution of ventilation and perfusion using central venous bolus of saline 5% during end-inspiratory pause. We defined unmatched units as the percentage of only ventilated units plus the percentage of only perfused units. Results Percentage of unmatched units was significantly higher in non-survivors compared to survivors (32[27–47]% vs. 21[17–27]%, p < 0.001). Percentage of unmatched units was an independent predictor of mortality (OR 1.22, 95% CI 1.07–1.39, p = 0.004) with an area under the ROC curve of 0.88 (95% CI 0.79–0.97, p < 0.001). The percentage of ventilation to the ventral region of the lung was higher than the percentage of ventilation to the dorsal region (32 [27–38]% vs. 18 [13–21]%, p < 0.001), while the opposite was true for perfusion (28 [22–38]% vs. 36 [32–44]%, p < 0.001). Higher percentage of only perfused units was correlated with lower dorsal ventilation (r =  − 0.486, p < 0.001) and with lower PaO2/FiO2 ratio (r =  − 0.293, p = 0.039). Conclusions EIT allows bedside assessment of unmatched ventilation and perfusion in mechanically ventilated patients with ARDS. Measurement of unmatched units could identify patients at higher risk of death and could guide personalized treatment